include/hw/i2c/aspeed_i2c.h | 2 ++ hw/i2c/aspeed_i2c.c | 27 +++++++++++++++++++++------ 2 files changed, 23 insertions(+), 6 deletions(-)
From: Kane-Chen-AS <kane_chen@aspeedtech.com> Currently, the Aspeed I2C controller uses a static naming convention for its buses (e.g., "aspeed.i2c.bus.0"). This approach leads to object name conflicts in machine models that incorporate multiple I2C controllers, such as an Aspeed SoC paired with an external IO expander or a co-processor like the AST1700. This patch series introduces a 'bus-label' property to the Aspeed I2C controller. By setting this property, higher-level platform code (e.g., the SoC realize function) can provide a unique prefix for the I2C buses. Changes in v1: Added bus-label property to AspeedI2CState. Added bus-name property to AspeedI2CBus. Modified aspeed_i2c_realize to generate bus names based on the label. Updated aspeed_i2c_bus_realize to use the customized name for bus initialization and memory region naming. Example usage: If a controller's bus-label is set to "ioexp0", its buses will be named "ioexp0.0", "ioexp0.1", etc., instead of the default "aspeed.i2c.bus.0". Any feedback or suggestions are appreciated. Best Regards, Kane Kane-Chen-AS (1): hw/i2c/aspeed: Introduce 'bus-label' to customize bus naming include/hw/i2c/aspeed_i2c.h | 2 ++ hw/i2c/aspeed_i2c.c | 27 +++++++++++++++++++++------ 2 files changed, 23 insertions(+), 6 deletions(-) -- 2.43.0
Hi, Cc'ing Markus. On 12/1/26 09:30, Kane Chen via qemu development wrote: > From: Kane-Chen-AS <kane_chen@aspeedtech.com> > > Currently, the Aspeed I2C controller uses a static naming convention > for its buses (e.g., "aspeed.i2c.bus.0"). This approach leads to > object name conflicts in machine models that incorporate multiple I2C > controllers, such as an Aspeed SoC paired with an external IO expander > or a co-processor like the AST1700. > Is this a side-effect of Problem 4: 'The /machine/unattached/ orphanage' described here? https://lore.kernel.org/qemu-devel/87o7d1i7ky.fsf@pond.sub.org/ This problem isn't specific to I2C nor Aspeed. > This patch series introduces a 'bus-label' property to the Aspeed I2C > controller. By setting this property, higher-level platform code > (e.g., the SoC realize function) can provide a unique prefix for the > I2C buses. > > Changes in v1: > > Added bus-label property to AspeedI2CState. > Added bus-name property to AspeedI2CBus. > Modified aspeed_i2c_realize to generate bus names based on the label. > Updated aspeed_i2c_bus_realize to use the customized name for bus > initialization and memory region naming. > > Example usage: If a controller's bus-label is set to "ioexp0", its buses > will be named "ioexp0.0", "ioexp0.1", etc., instead of the default > "aspeed.i2c.bus.0". > > Any feedback or suggestions are appreciated. > > Best Regards, > Kane > > Kane-Chen-AS (1): > hw/i2c/aspeed: Introduce 'bus-label' to customize bus naming > > include/hw/i2c/aspeed_i2c.h | 2 ++ > hw/i2c/aspeed_i2c.c | 27 +++++++++++++++++++++------ > 2 files changed, 23 insertions(+), 6 deletions(-) >
On 1/15/26 20:47, Philippe Mathieu-Daudé wrote: > Hi, > > Cc'ing Markus. > > On 12/1/26 09:30, Kane Chen via qemu development wrote: >> From: Kane-Chen-AS <kane_chen@aspeedtech.com> >> >> Currently, the Aspeed I2C controller uses a static naming convention >> for its buses (e.g., "aspeed.i2c.bus.0"). This approach leads to >> object name conflicts in machine models that incorporate multiple I2C >> controllers, such as an Aspeed SoC paired with an external IO expander >> or a co-processor like the AST1700. >> > > Is this a side-effect of Problem 4: 'The /machine/unattached/ orphanage' > described here? > https://lore.kernel.org/qemu-devel/87o7d1i7ky.fsf@pond.sub.org/ > > This problem isn't specific to I2C nor Aspeed. See the discussion here : https://lore.kernel.org/qemu-devel/006fa26f-6b84-4e82-b6e1-7d1353579441@kaod.org/ The Aspeed SoC has 3*16 I2C buses attached on 3 different I2C controllers plus the I2C/I3C buses. We need to find a way to distinguish these groups at the QEMU machine level to be able to add devices on the right bus when using the command line. Suggestions welcome ! Thanks, C. > >> This patch series introduces a 'bus-label' property to the Aspeed I2C >> controller. By setting this property, higher-level platform code >> (e.g., the SoC realize function) can provide a unique prefix for the >> I2C buses. >> >> Changes in v1: >> >> Added bus-label property to AspeedI2CState. >> Added bus-name property to AspeedI2CBus. >> Modified aspeed_i2c_realize to generate bus names based on the label. >> Updated aspeed_i2c_bus_realize to use the customized name for bus >> initialization and memory region naming. >> >> Example usage: If a controller's bus-label is set to "ioexp0", its buses >> will be named "ioexp0.0", "ioexp0.1", etc., instead of the default >> "aspeed.i2c.bus.0". >> >> Any feedback or suggestions are appreciated. >> >> Best Regards, >> Kane >> >> Kane-Chen-AS (1): >> hw/i2c/aspeed: Introduce 'bus-label' to customize bus naming >> >> include/hw/i2c/aspeed_i2c.h | 2 ++ >> hw/i2c/aspeed_i2c.c | 27 +++++++++++++++++++++------ >> 2 files changed, 23 insertions(+), 6 deletions(-) >> >
Cédric Le Goater <clg@kaod.org> writes: > On 1/15/26 20:47, Philippe Mathieu-Daudé wrote: >> Hi, >> Cc'ing Markus. >> On 12/1/26 09:30, Kane Chen via qemu development wrote: >>> From: Kane-Chen-AS <kane_chen@aspeedtech.com> >>> >>> Currently, the Aspeed I2C controller uses a static naming convention >>> for its buses (e.g., "aspeed.i2c.bus.0"). This approach leads to >>> object name conflicts in machine models that incorporate multiple I2C >>> controllers, such as an Aspeed SoC paired with an external IO expander >>> or a co-processor like the AST1700. >>> >> Is this a side-effect of Problem 4: 'The /machine/unattached/ orphanage' >> described here? >> https://lore.kernel.org/qemu-devel/87o7d1i7ky.fsf@pond.sub.org/ >> This problem isn't specific to I2C nor Aspeed. > > > See the discussion here : > > https://lore.kernel.org/qemu-devel/006fa26f-6b84-4e82-b6e1-7d1353579441@kaod.org/ > > The Aspeed SoC has 3*16 I2C buses attached on 3 different I2C > controllers plus the I2C/I3C buses. We need to find a way to > distinguish these groups at the QEMU machine level to be able > to add devices on the right bus when using the command line. > > Suggestions welcome ! Please show me how to start a QEMU with the 48 I2C mentioned above, complete with output of "info qtree".
Hello,
On 1/19/26 15:25, Markus Armbruster wrote:
> Cédric Le Goater <clg@kaod.org> writes:
>
>> On 1/15/26 20:47, Philippe Mathieu-Daudé wrote:
>>> Hi,
>>> Cc'ing Markus.
>>> On 12/1/26 09:30, Kane Chen via qemu development wrote:
>>>> From: Kane-Chen-AS <kane_chen@aspeedtech.com>
>>>>
>>>> Currently, the Aspeed I2C controller uses a static naming convention
>>>> for its buses (e.g., "aspeed.i2c.bus.0"). This approach leads to
>>>> object name conflicts in machine models that incorporate multiple I2C
>>>> controllers, such as an Aspeed SoC paired with an external IO expander
>>>> or a co-processor like the AST1700.
>>>>
>>> Is this a side-effect of Problem 4: 'The /machine/unattached/ orphanage'
>>> described here?
>>> https://lore.kernel.org/qemu-devel/87o7d1i7ky.fsf@pond.sub.org/
>>> This problem isn't specific to I2C nor Aspeed.
>>
>>
>> See the discussion here :
>>
>> https://lore.kernel.org/qemu-devel/006fa26f-6b84-4e82-b6e1-7d1353579441@kaod.org/
>>
>> The Aspeed SoC has 3*16 I2C buses attached on 3 different I2C
>> controllers plus the I2C/I3C buses. We need to find a way to
>> distinguish these groups at the QEMU machine level to be able
>> to add devices on the right bus when using the command line.
>>
>> Suggestions welcome !
>
> Please show me how to start a QEMU with the 48 I2C mentioned above,
> complete with output of "info qtree".
Clone
https://github.com/legoater/qemu/commits/aspeed-11.0
Download
https://github.com/AspeedTech-BMC/openbmc/releases/download/v09.08/ast2700-default-obmc.tar.gz
And run :
qemu-system-aarch64 -M ast2700a1-evb -m 8G -smp 4 -net nic,macaddr=,netdev=net0 -netdev user,id=net0,hostfwd=::2207-:22 -drive file=path/to/ast2700-default/image-bmc,format=raw,if=mtd -nographic -serial mon:stdio -snapshot
Today, to attach an I2C device on one of the Aspeed SoC I2C buses :
-device tmp105,bus=aspeed.i2c.bus.1,address=0x4d,id=tmp-test
The Aspeed SoC I2C bus names follow the "aspeed.i2c.bus.X" format.
This is the model typename. The 2 new IO expander models attached
to the Aspeed SoC have an extra 16 I2C buses each. These buses use
an "ioexpX.Y" name, as proposed in the aspeed-next branch.
Attaching a device to one of the IO expanders I2C buses would be :
-device tmp105,bus=ioexp0.1,address=0x4d,id=tmp-test
See the qtree below.
Thanks,
C.
(qemu) info qtree
bus: main-system-bus
type System
dev: unimplemented-device, id ""
size = 16777216 (0x1000000)
name = "aspeed.iomem1"
mmio ffffffffffffffff/0000000001000000
dev: unimplemented-device, id ""
size = 16777216 (0x1000000)
name = "aspeed.iomem0"
mmio ffffffffffffffff/0000000001000000
dev: unimplemented-device, id ""
size = 16646144 (0xfe0000)
name = "aspeed.io"
mmio ffffffffffffffff/0000000000fe0000
dev: unimplemented-device, id ""
size = 262144 (0x40000)
name = "aspeed.dpmcu"
mmio ffffffffffffffff/0000000000040000
dev: unimplemented-device, id ""
size = 65536 (0x10000)
name = "ioexp-i3c"
mmio ffffffffffffffff/0000000000010000
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/ioexp[1]/ioexp-scu[0]"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/ioexp[1]/ioexp-scu[0]"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/ioexp[1]/ioexp-scu[0]"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/ioexp[1]/ioexp-scu[0]"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/ioexp[1]/ioexp-scu[0]"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/ioexp[1]/ioexp-scu[0]"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/ioexp[1]/ioexp-scu[0]"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/ioexp[1]/ioexp-scu[0]"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/ioexp[1]/ioexp-scu[0]"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.sgpio-ast2700, id ""
gpio-out "sysbus-irq" 1
mmio ffffffffffffffff/0000000000001000
dev: aspeed.sgpio-ast2700, id ""
gpio-out "sysbus-irq" 1
mmio ffffffffffffffff/0000000000001000
dev: aspeed.ltpi-ctrl, id ""
mmio ffffffffffffffff/0000000000000900
dev: aspeed.pwm, id ""
gpio-out "sysbus-irq" 1
mmio ffffffffffffffff/0000000000001000
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 15 (0xf)
controller = "/machine/soc/ioexp[1]/ioexp-i2c[0]"
bus-name = "ioexp1.15"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp1.15
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 14 (0xe)
controller = "/machine/soc/ioexp[1]/ioexp-i2c[0]"
bus-name = "ioexp1.14"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp1.14
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 13 (0xd)
controller = "/machine/soc/ioexp[1]/ioexp-i2c[0]"
bus-name = "ioexp1.13"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp1.13
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 12 (0xc)
controller = "/machine/soc/ioexp[1]/ioexp-i2c[0]"
bus-name = "ioexp1.12"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp1.12
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 11 (0xb)
controller = "/machine/soc/ioexp[1]/ioexp-i2c[0]"
bus-name = "ioexp1.11"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp1.11
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 10 (0xa)
controller = "/machine/soc/ioexp[1]/ioexp-i2c[0]"
bus-name = "ioexp1.10"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp1.10
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 9 (0x9)
controller = "/machine/soc/ioexp[1]/ioexp-i2c[0]"
bus-name = "ioexp1.9"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp1.9
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 8 (0x8)
controller = "/machine/soc/ioexp[1]/ioexp-i2c[0]"
bus-name = "ioexp1.8"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp1.8
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 7 (0x7)
controller = "/machine/soc/ioexp[1]/ioexp-i2c[0]"
bus-name = "ioexp1.7"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp1.7
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 6 (0x6)
controller = "/machine/soc/ioexp[1]/ioexp-i2c[0]"
bus-name = "ioexp1.6"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp1.6
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 5 (0x5)
controller = "/machine/soc/ioexp[1]/ioexp-i2c[0]"
bus-name = "ioexp1.5"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp1.5
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 4 (0x4)
controller = "/machine/soc/ioexp[1]/ioexp-i2c[0]"
bus-name = "ioexp1.4"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp1.4
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 3 (0x3)
controller = "/machine/soc/ioexp[1]/ioexp-i2c[0]"
bus-name = "ioexp1.3"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp1.3
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 2 (0x2)
controller = "/machine/soc/ioexp[1]/ioexp-i2c[0]"
bus-name = "ioexp1.2"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp1.2
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 1 (0x1)
controller = "/machine/soc/ioexp[1]/ioexp-i2c[0]"
bus-name = "ioexp1.1"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp1.1
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 0 (0x0)
controller = "/machine/soc/ioexp[1]/ioexp-i2c[0]"
bus-name = "ioexp1.0"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp1.0
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c-ast2700, id ""
gpio-out "sysbus-irq" 1
dram = "/machine/soc/ioexp[1]/aspeed.ast1700[0]"
bus-label = "ioexp1"
mmio ffffffffffffffff/0000000000002000
dev: aspeed.gpio-ast2700, id ""
gpio-out "sysbus-irq" 213
mmio ffffffffffffffff/0000000000001000
dev: aspeed.scu-ast2700, id ""
silicon-rev = 100729091 (0x6010103)
hw-strap1 = 0 (0x0)
hw-strap2 = 0 (0x0)
hw-prot-key = 0 (0x0)
mmio ffffffffffffffff/0000000000001000
dev: aspeed.adc.engine, id ""
gpio-out "sysbus-irq" 1
engine-id = 1 (0x1)
nr-channels = 8 (0x8)
mmio ffffffffffffffff/0000000000000100
dev: aspeed.adc.engine, id ""
gpio-out "sysbus-irq" 1
engine-id = 0 (0x0)
nr-channels = 8 (0x8)
mmio ffffffffffffffff/0000000000000100
dev: aspeed.adc-ast2700, id ""
gpio-out "sysbus-irq" 1
gpio-in "" 2
mmio ffffffffffffffff/0000000000001000
dev: aspeed.smc.flash, id ""
cs = 1 (0x1)
controller = "/machine/soc/ioexp[1]/ioexp-spi[0]"
mmio ffffffffffffffff/0000000008000000
dev: aspeed.smc.flash, id ""
cs = 0 (0x0)
controller = "/machine/soc/ioexp[1]/ioexp-spi[0]"
mmio ffffffffffffffff/0000000008000000
dev: aspeed.spi0-ast2700, id ""
gpio-out "cs" 2
gpio-out "sysbus-irq" 1
inject-failure = false
dram-base = 0 (0x0)
dram = "/machine/soc/ioexp[1]/aspeed.ast1700[0]"
mmio ffffffffffffffff/0000000000000100
mmio ffffffffffffffff/0000000040000000
bus: ssi.5
type SSI
dev: serial-mm, id ""
gpio-out "sysbus-irq" 1
regshift = 2 (0x2)
endianness = 2 (0x2)
mmio ffffffffffffffff/0000000000000020
dev: aspeed.ast1700, id ""
board-idx = 1 (0x1)
silicon-rev = 100729091 (0x6010103)
mmio 0000000050000000/0000000001000000
dev: unimplemented-device, id ""
size = 65536 (0x10000)
name = "ioexp-i3c"
mmio ffffffffffffffff/0000000000010000
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/ioexp[0]/ioexp-scu[0]"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/ioexp[0]/ioexp-scu[0]"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/ioexp[0]/ioexp-scu[0]"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/ioexp[0]/ioexp-scu[0]"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/ioexp[0]/ioexp-scu[0]"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/ioexp[0]/ioexp-scu[0]"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/ioexp[0]/ioexp-scu[0]"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/ioexp[0]/ioexp-scu[0]"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/ioexp[0]/ioexp-scu[0]"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.sgpio-ast2700, id ""
gpio-out "sysbus-irq" 1
mmio ffffffffffffffff/0000000000001000
dev: aspeed.sgpio-ast2700, id ""
gpio-out "sysbus-irq" 1
mmio ffffffffffffffff/0000000000001000
dev: aspeed.ltpi-ctrl, id ""
mmio ffffffffffffffff/0000000000000900
dev: aspeed.pwm, id ""
gpio-out "sysbus-irq" 1
mmio ffffffffffffffff/0000000000001000
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 15 (0xf)
controller = "/machine/soc/ioexp[0]/ioexp-i2c[0]"
bus-name = "ioexp0.15"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp0.15
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 14 (0xe)
controller = "/machine/soc/ioexp[0]/ioexp-i2c[0]"
bus-name = "ioexp0.14"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp0.14
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 13 (0xd)
controller = "/machine/soc/ioexp[0]/ioexp-i2c[0]"
bus-name = "ioexp0.13"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp0.13
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 12 (0xc)
controller = "/machine/soc/ioexp[0]/ioexp-i2c[0]"
bus-name = "ioexp0.12"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp0.12
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 11 (0xb)
controller = "/machine/soc/ioexp[0]/ioexp-i2c[0]"
bus-name = "ioexp0.11"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp0.11
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 10 (0xa)
controller = "/machine/soc/ioexp[0]/ioexp-i2c[0]"
bus-name = "ioexp0.10"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp0.10
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 9 (0x9)
controller = "/machine/soc/ioexp[0]/ioexp-i2c[0]"
bus-name = "ioexp0.9"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp0.9
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 8 (0x8)
controller = "/machine/soc/ioexp[0]/ioexp-i2c[0]"
bus-name = "ioexp0.8"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp0.8
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 7 (0x7)
controller = "/machine/soc/ioexp[0]/ioexp-i2c[0]"
bus-name = "ioexp0.7"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp0.7
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 6 (0x6)
controller = "/machine/soc/ioexp[0]/ioexp-i2c[0]"
bus-name = "ioexp0.6"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp0.6
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 5 (0x5)
controller = "/machine/soc/ioexp[0]/ioexp-i2c[0]"
bus-name = "ioexp0.5"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp0.5
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 4 (0x4)
controller = "/machine/soc/ioexp[0]/ioexp-i2c[0]"
bus-name = "ioexp0.4"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp0.4
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 3 (0x3)
controller = "/machine/soc/ioexp[0]/ioexp-i2c[0]"
bus-name = "ioexp0.3"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp0.3
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 2 (0x2)
controller = "/machine/soc/ioexp[0]/ioexp-i2c[0]"
bus-name = "ioexp0.2"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp0.2
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 1 (0x1)
controller = "/machine/soc/ioexp[0]/ioexp-i2c[0]"
bus-name = "ioexp0.1"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp0.1
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 0 (0x0)
controller = "/machine/soc/ioexp[0]/ioexp-i2c[0]"
bus-name = "ioexp0.0"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: ioexp0.0
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c-ast2700, id ""
gpio-out "sysbus-irq" 1
dram = "/machine/soc/ioexp[0]/aspeed.ast1700[0]"
bus-label = "ioexp0"
mmio ffffffffffffffff/0000000000002000
dev: aspeed.gpio-ast2700, id ""
gpio-out "sysbus-irq" 213
mmio ffffffffffffffff/0000000000001000
dev: aspeed.scu-ast2700, id ""
silicon-rev = 100729091 (0x6010103)
hw-strap1 = 0 (0x0)
hw-strap2 = 0 (0x0)
hw-prot-key = 0 (0x0)
mmio ffffffffffffffff/0000000000001000
dev: aspeed.adc.engine, id ""
gpio-out "sysbus-irq" 1
engine-id = 1 (0x1)
nr-channels = 8 (0x8)
mmio ffffffffffffffff/0000000000000100
dev: aspeed.adc.engine, id ""
gpio-out "sysbus-irq" 1
engine-id = 0 (0x0)
nr-channels = 8 (0x8)
mmio ffffffffffffffff/0000000000000100
dev: aspeed.adc-ast2700, id ""
gpio-out "sysbus-irq" 1
gpio-in "" 2
mmio ffffffffffffffff/0000000000001000
dev: aspeed.smc.flash, id ""
cs = 1 (0x1)
controller = "/machine/soc/ioexp[0]/ioexp-spi[0]"
mmio ffffffffffffffff/0000000008000000
dev: aspeed.smc.flash, id ""
cs = 0 (0x0)
controller = "/machine/soc/ioexp[0]/ioexp-spi[0]"
mmio ffffffffffffffff/0000000008000000
dev: aspeed.spi0-ast2700, id ""
gpio-out "cs" 2
gpio-out "sysbus-irq" 1
inject-failure = false
dram-base = 0 (0x0)
dram = "/machine/soc/ioexp[0]/aspeed.ast1700[0]"
mmio ffffffffffffffff/0000000000000100
mmio ffffffffffffffff/0000000040000000
bus: ssi.4
type SSI
dev: serial-mm, id ""
gpio-out "sysbus-irq" 1
regshift = 2 (0x2)
endianness = 2 (0x2)
mmio ffffffffffffffff/0000000000000020
dev: aspeed.ast1700, id ""
board-idx = 0 (0x0)
silicon-rev = 100729091 (0x6010103)
mmio 0000000030000000/0000000001000000
dev: aspeed.ltpi-ctrl, id ""
mmio ffffffffffffffff/0000000000000900
dev: aspeed.ltpi-ctrl, id ""
mmio ffffffffffffffff/0000000000000900
dev: aspeed.pcie-rc, id ""
gpio-out "sysbus-irq" 1
bus-nr = 0 (0x0)
has-rd = false
rp-addr = 0 (0x0)
msi-addr = 240 (0xf0)
dram-base = 17179869184 (0x400000000)
dram = "/objects/ram/ram[0]"
x-config-reg-migration-enabled = true
bypass-iommu = false
mmio ffffffffffffffff/0000000010000000
mmio ffffffffffffffff/ffffffffffffffff
mmio ffffffffffffffff/0000000000010000
bus: pcie.rc2
type PCIE
dev: aspeed.pcie-root-port, id ""
power_controller_present = true
disable-acs = false
chassis = 2 (0x2)
slot = 0 (0x0)
hotplug = true
x-do-not-expose-native-hotplug-cap = false
port = 0 (0x0)
aer_log_max = 8 (0x8)
x-pci-express-writeable-slt-bug = false
addr = 00.0
romfile = ""
romsize = 4294967295 (0xffffffff)
rombar = -1 (0xffffffffffffffff)
multifunction = false
x-pcie-lnksta-dllla = true
x-pcie-extcap-init = true
failover_pair_id = ""
acpi-index = 0 (0x0)
x-pcie-err-unc-mask = true
x-pcie-ari-nextfn-1 = false
x-max-bounce-buffer-size = 4096 (4 KiB)
sriov-pf = ""
x-pcie-ext-tag = true
busnr = 0 (0x0)
class PCI bridge, addr 00:00.0, pci id 1a03:1150 (sub 0000:0000)
bus: pcie.2
type PCIE
dev: aspeed.pcie-cfg-ast2700, id ""
id = 2 (0x2)
mmio ffffffffffffffff/0000000000000100
dev: aspeed.pcie-phy-ast2700, id ""
id = 2 (0x2)
mmio ffffffffffffffff/0000000000000800
dev: aspeed.pcie-rc, id ""
gpio-out "sysbus-irq" 1
bus-nr = 0 (0x0)
has-rd = false
rp-addr = 0 (0x0)
msi-addr = 240 (0xf0)
dram-base = 17179869184 (0x400000000)
dram = "/objects/ram/ram[0]"
x-config-reg-migration-enabled = true
bypass-iommu = false
mmio ffffffffffffffff/0000000010000000
mmio ffffffffffffffff/ffffffffffffffff
mmio ffffffffffffffff/0000000000010000
bus: pcie.rc1
type PCIE
dev: aspeed.pcie-root-port, id ""
power_controller_present = true
disable-acs = false
chassis = 1 (0x1)
slot = 0 (0x0)
hotplug = true
x-do-not-expose-native-hotplug-cap = false
port = 0 (0x0)
aer_log_max = 8 (0x8)
x-pci-express-writeable-slt-bug = false
addr = 00.0
romfile = ""
romsize = 4294967295 (0xffffffff)
rombar = -1 (0xffffffffffffffff)
multifunction = false
x-pcie-lnksta-dllla = true
x-pcie-extcap-init = true
failover_pair_id = ""
acpi-index = 0 (0x0)
x-pcie-err-unc-mask = true
x-pcie-ari-nextfn-1 = false
x-max-bounce-buffer-size = 4096 (4 KiB)
sriov-pf = ""
x-pcie-ext-tag = true
busnr = 0 (0x0)
class PCI bridge, addr 00:00.0, pci id 1a03:1150 (sub 0000:0000)
bus: pcie.1
type PCIE
dev: aspeed.pcie-cfg-ast2700, id ""
id = 1 (0x1)
mmio ffffffffffffffff/0000000000000100
dev: aspeed.pcie-phy-ast2700, id ""
id = 1 (0x1)
mmio ffffffffffffffff/0000000000000800
dev: aspeed.pcie-rc, id ""
gpio-out "sysbus-irq" 1
bus-nr = 0 (0x0)
has-rd = false
rp-addr = 0 (0x0)
msi-addr = 240 (0xf0)
dram-base = 17179869184 (0x400000000)
dram = "/objects/ram/ram[0]"
x-config-reg-migration-enabled = true
bypass-iommu = false
mmio ffffffffffffffff/0000000010000000
mmio ffffffffffffffff/ffffffffffffffff
mmio ffffffffffffffff/0000000000010000
bus: pcie.rc0
type PCIE
dev: aspeed.pcie-root-port, id ""
power_controller_present = true
disable-acs = false
chassis = 0 (0x0)
slot = 0 (0x0)
hotplug = true
x-do-not-expose-native-hotplug-cap = false
port = 0 (0x0)
aer_log_max = 8 (0x8)
x-pci-express-writeable-slt-bug = false
addr = 00.0
romfile = ""
romsize = 4294967295 (0xffffffff)
rombar = -1 (0xffffffffffffffff)
multifunction = false
x-pcie-lnksta-dllla = true
x-pcie-extcap-init = true
failover_pair_id = ""
acpi-index = 0 (0x0)
x-pcie-err-unc-mask = true
x-pcie-ari-nextfn-1 = false
x-max-bounce-buffer-size = 4096 (4 KiB)
sriov-pf = ""
x-pcie-ext-tag = true
busnr = 0 (0x0)
class PCI bridge, addr 00:00.0, pci id 1a03:1150 (sub 0000:0000)
bus: pcie.0
type PCIE
dev: aspeed.pcie-cfg-ast2700, id ""
id = 0 (0x0)
mmio ffffffffffffffff/0000000000000100
dev: aspeed.pcie-phy-ast2700, id ""
id = 0 (0x0)
mmio ffffffffffffffff/0000000000000800
dev: aspeed.hace-ast2700, id ""
gpio-out "sysbus-irq" 1
dram = "/objects/ram/ram[0]"
mmio ffffffffffffffff/000000000000009c
dev: aspeed.timer-ast2700, id ""
gpio-out "sysbus-irq" 8
scu = "/machine/soc/scu"
mmio ffffffffffffffff/0000000000001000
dev: generic-sdhci, id ""
gpio-out "sysbus-irq" 1
endianness = 2 (0x2)
sd-spec-version = 2 (0x2)
uhs = 0 (0x0)
vendor = 0 (0x0)
capareg = 30567563392 (0x71df80080)
maxcurr = 0 (0x0)
pending-insert-quirk = false
dma = ""
wp-inverted = false
mmio ffffffffffffffff/0000000000000100
bus: sd-bus
type sdhci-bus
dev: aspeed.sdhci-ast2700, id ""
gpio-out "sysbus-irq" 1
gpio-in "" 1
num-slots = 1 (0x1)
mmio ffffffffffffffff/0000000000001000
dev: generic-sdhci, id ""
gpio-out "sysbus-irq" 1
endianness = 2 (0x2)
sd-spec-version = 2 (0x2)
uhs = 0 (0x0)
vendor = 0 (0x0)
capareg = 30567563392 (0x71df80080)
maxcurr = 0 (0x0)
pending-insert-quirk = false
dma = ""
wp-inverted = false
mmio ffffffffffffffff/0000000000000100
bus: sd-bus
type sdhci-bus
dev: aspeed.sdhci-ast2700, id ""
gpio-out "sysbus-irq" 1
gpio-in "" 1
num-slots = 1 (0x1)
mmio ffffffffffffffff/0000000000001000
dev: aspeed.rtc, id ""
gpio-out "sysbus-irq" 1
mmio ffffffffffffffff/0000000000000018
dev: aspeed.sgpio-ast2700, id ""
gpio-out "sysbus-irq" 1
mmio ffffffffffffffff/0000000000001000
dev: aspeed.sgpio-ast2700, id ""
gpio-out "sysbus-irq" 1
mmio ffffffffffffffff/0000000000001000
dev: aspeed.gpio-ast2700, id ""
gpio-out "sysbus-irq" 213
mmio ffffffffffffffff/0000000000001000
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 15 (0xf)
controller = "/machine/soc/i2c"
bus-name = "aspeed.i2c.bus.15"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: aspeed.i2c.bus.15
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 14 (0xe)
controller = "/machine/soc/i2c"
bus-name = "aspeed.i2c.bus.14"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: aspeed.i2c.bus.14
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 13 (0xd)
controller = "/machine/soc/i2c"
bus-name = "aspeed.i2c.bus.13"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: aspeed.i2c.bus.13
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 12 (0xc)
controller = "/machine/soc/i2c"
bus-name = "aspeed.i2c.bus.12"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: aspeed.i2c.bus.12
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 11 (0xb)
controller = "/machine/soc/i2c"
bus-name = "aspeed.i2c.bus.11"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: aspeed.i2c.bus.11
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 10 (0xa)
controller = "/machine/soc/i2c"
bus-name = "aspeed.i2c.bus.10"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: aspeed.i2c.bus.10
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 9 (0x9)
controller = "/machine/soc/i2c"
bus-name = "aspeed.i2c.bus.9"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: aspeed.i2c.bus.9
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 8 (0x8)
controller = "/machine/soc/i2c"
bus-name = "aspeed.i2c.bus.8"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: aspeed.i2c.bus.8
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 7 (0x7)
controller = "/machine/soc/i2c"
bus-name = "aspeed.i2c.bus.7"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: aspeed.i2c.bus.7
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 6 (0x6)
controller = "/machine/soc/i2c"
bus-name = "aspeed.i2c.bus.6"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: aspeed.i2c.bus.6
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 5 (0x5)
controller = "/machine/soc/i2c"
bus-name = "aspeed.i2c.bus.5"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: aspeed.i2c.bus.5
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 4 (0x4)
controller = "/machine/soc/i2c"
bus-name = "aspeed.i2c.bus.4"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: aspeed.i2c.bus.4
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 3 (0x3)
controller = "/machine/soc/i2c"
bus-name = "aspeed.i2c.bus.3"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: aspeed.i2c.bus.3
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 2 (0x2)
controller = "/machine/soc/i2c"
bus-name = "aspeed.i2c.bus.2"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: aspeed.i2c.bus.2
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 1 (0x1)
controller = "/machine/soc/i2c"
bus-name = "aspeed.i2c.bus.1"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: aspeed.i2c.bus.1
type i2c-bus
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c.bus, id ""
gpio-out "sysbus-irq" 1
bus-id = 0 (0x0)
controller = "/machine/soc/i2c"
bus-name = "aspeed.i2c.bus.0"
mmio ffffffffffffffff/0000000000000080
mmio ffffffffffffffff/0000000000000020
bus: aspeed.i2c.bus.0
type i2c-bus
dev: tmp105, id ""
gpio-out "" 1
address = 77 (0x4d)
dev: aspeed.i2c.slave, id ""
address = 255 (0xff)
dev: aspeed.i2c-ast2700, id ""
gpio-out "sysbus-irq" 1
dram = "/objects/ram/ram[0]"
bus-label = "aspeed.i2c.bus"
mmio ffffffffffffffff/0000000000002000
dev: aspeed.adc.engine, id ""
gpio-out "sysbus-irq" 1
engine-id = 1 (0x1)
nr-channels = 8 (0x8)
mmio ffffffffffffffff/0000000000000100
dev: aspeed.adc.engine, id ""
gpio-out "sysbus-irq" 1
engine-id = 0 (0x0)
nr-channels = 8 (0x8)
mmio ffffffffffffffff/0000000000000100
dev: aspeed.adc-ast2700, id ""
gpio-out "sysbus-irq" 1
gpio-in "" 2
mmio ffffffffffffffff/0000000000001000
dev: aspeed.sliio-ast2700, id ""
mmio ffffffffffffffff/0000000000000500
dev: aspeed.sli-ast2700, id ""
mmio ffffffffffffffff/0000000000000500
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/scu"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/scu"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/scu"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/scu"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/scu"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/scu"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/scu"
mmio ffffffffffffffff/0000000000000080
dev: aspeed.wdt-ast2700, id ""
scu = "/machine/soc/scu"
mmio ffffffffffffffff/0000000000000080
dev: aspeed-mmi, id ""
nic = "/machine/soc/ftgmac100[2]"
mmio ffffffffffffffff/0000000000000008
dev: ftgmac100, id ""
gpio-out "sysbus-irq" 1
aspeed = true
mac = "52:54:00:12:34:58"
netdev = ""
dma64 = true
mmio ffffffffffffffff/0000000000001000
dev: aspeed-mmi, id ""
nic = "/machine/soc/ftgmac100[1]"
mmio ffffffffffffffff/0000000000000008
dev: ftgmac100, id ""
gpio-out "sysbus-irq" 1
aspeed = true
mac = "52:54:00:12:34:57"
netdev = ""
dma64 = true
mmio ffffffffffffffff/0000000000001000
dev: aspeed-mmi, id ""
nic = "/machine/soc/ftgmac100[0]"
mmio ffffffffffffffff/0000000000000008
dev: ftgmac100, id ""
gpio-out "sysbus-irq" 1
aspeed = true
mac = "52:54:00:12:34:56"
netdev = "net0"
dma64 = true
mmio ffffffffffffffff/0000000000001000
dev: aspeed.sdmc-ast2700, id ""
max-ram-size = 8589934592 (0x200000000)
unlocked = true
mmio ffffffffffffffff/0000000000001000
dev: platform-ehci-usb, id ""
gpio-out "sysbus-irq" 1
maxframes = 128 (0x80)
companion-enable = false
mmio ffffffffffffffff/0000000000001000
bus: usb-bus.3
type usb-bus
dev: platform-ehci-usb, id ""
gpio-out "sysbus-irq" 1
maxframes = 128 (0x80)
companion-enable = false
mmio ffffffffffffffff/0000000000001000
bus: usb-bus.2
type usb-bus
dev: platform-ehci-usb, id ""
gpio-out "sysbus-irq" 1
maxframes = 128 (0x80)
companion-enable = false
mmio ffffffffffffffff/0000000000001000
bus: usb-bus.1
type usb-bus
dev: platform-ehci-usb, id ""
gpio-out "sysbus-irq" 1
maxframes = 128 (0x80)
companion-enable = false
mmio ffffffffffffffff/0000000000001000
bus: usb-bus.0
type usb-bus
dev: aspeed.smc.flash, id ""
cs = 1 (0x1)
controller = "/machine/soc/spi[2]"
mmio ffffffffffffffff/0000000000000000
dev: aspeed.smc.flash, id ""
cs = 0 (0x0)
controller = "/machine/soc/spi[2]"
mmio ffffffffffffffff/0000000008000000
dev: aspeed.spi2-ast2700, id ""
gpio-out "cs" 2
gpio-out "sysbus-irq" 1
inject-failure = false
dram-base = 0 (0x0)
dram = "/objects/ram/ram[0]"
mmio ffffffffffffffff/0000000000000100
mmio ffffffffffffffff/0000000040000000
bus: ssi.3
type SSI
dev: aspeed.smc.flash, id ""
cs = 1 (0x1)
controller = "/machine/soc/spi[1]"
mmio ffffffffffffffff/0000000000000000
dev: aspeed.smc.flash, id ""
cs = 0 (0x0)
controller = "/machine/soc/spi[1]"
mmio ffffffffffffffff/0000000008000000
dev: aspeed.spi1-ast2700, id ""
gpio-out "cs" 2
gpio-out "sysbus-irq" 1
inject-failure = false
dram-base = 0 (0x0)
dram = "/objects/ram/ram[0]"
mmio ffffffffffffffff/0000000000000100
mmio ffffffffffffffff/0000000040000000
bus: ssi.2
type SSI
dev: aspeed.smc.flash, id ""
cs = 1 (0x1)
controller = "/machine/soc/spi[0]"
mmio ffffffffffffffff/0000000008000000
dev: aspeed.smc.flash, id ""
cs = 0 (0x0)
controller = "/machine/soc/spi[0]"
mmio ffffffffffffffff/0000000008000000
dev: aspeed.spi0-ast2700, id ""
gpio-out "cs" 2
gpio-out "sysbus-irq" 1
inject-failure = false
dram-base = 0 (0x0)
dram = "/objects/ram/ram[0]"
mmio ffffffffffffffff/0000000000000100
mmio ffffffffffffffff/0000000040000000
bus: ssi.1
type SSI
dev: w25q512jv, id ""
gpio-in "WP#" 1
gpio-in "ssi-gpio-cs" 1
write-enable = false
nonvolatile-cfg = 36863 (0x8fff)
spansion-cr1nv = 0 (0x0)
spansion-cr2nv = 8 (0x8)
spansion-cr3nv = 2 (0x2)
spansion-cr4nv = 16 (0x10)
drive = ""
cs = 0 (0x0)
dev: aspeed.smc.flash, id ""
cs = 2 (0x2)
controller = "/machine/soc/fmc"
mmio ffffffffffffffff/0000000008000000
dev: aspeed.smc.flash, id ""
cs = 1 (0x1)
controller = "/machine/soc/fmc"
mmio ffffffffffffffff/0000000008000000
dev: aspeed.smc.flash, id ""
cs = 0 (0x0)
controller = "/machine/soc/fmc"
mmio ffffffffffffffff/0000000008010000
dev: aspeed.fmc-ast2700, id ""
gpio-out "cs" 3
gpio-out "sysbus-irq" 1
inject-failure = false
dram-base = 17179869184 (0x400000000)
dram = "/objects/ram/ram[0]"
mmio ffffffffffffffff/0000000000000100
mmio ffffffffffffffff/0000000040000000
bus: ssi.0
type SSI
dev: w25q01jvq, id ""
gpio-in "WP#" 1
gpio-in "ssi-gpio-cs" 1
write-enable = false
nonvolatile-cfg = 36863 (0x8fff)
spansion-cr1nv = 0 (0x0)
spansion-cr2nv = 8 (0x8)
spansion-cr3nv = 2 (0x2)
spansion-cr4nv = 16 (0x10)
drive = ""
cs = 1 (0x1)
dev: w25q01jvq, id ""
gpio-in "WP#" 1
gpio-in "ssi-gpio-cs" 1
write-enable = false
nonvolatile-cfg = 36863 (0x8fff)
spansion-cr1nv = 0 (0x0)
spansion-cr2nv = 8 (0x8)
spansion-cr3nv = 2 (0x2)
spansion-cr4nv = 16 (0x10)
drive = "mtd0"
cs = 0 (0x0)
dev: serial-mm, id ""
gpio-out "sysbus-irq" 1
regshift = 2 (0x2)
endianness = 2 (0x2)
mmio ffffffffffffffff/0000000000000020
dev: serial-mm, id ""
gpio-out "sysbus-irq" 1
regshift = 2 (0x2)
endianness = 2 (0x2)
mmio ffffffffffffffff/0000000000000020
dev: serial-mm, id ""
gpio-out "sysbus-irq" 1
regshift = 2 (0x2)
endianness = 2 (0x2)
mmio ffffffffffffffff/0000000000000020
dev: serial-mm, id ""
gpio-out "sysbus-irq" 1
regshift = 2 (0x2)
endianness = 2 (0x2)
mmio ffffffffffffffff/0000000000000020
dev: serial-mm, id ""
gpio-out "sysbus-irq" 1
regshift = 2 (0x2)
endianness = 2 (0x2)
mmio ffffffffffffffff/0000000000000020
dev: serial-mm, id ""
gpio-out "sysbus-irq" 1
regshift = 2 (0x2)
endianness = 2 (0x2)
mmio ffffffffffffffff/0000000000000020
dev: serial-mm, id ""
gpio-out "sysbus-irq" 1
regshift = 2 (0x2)
endianness = 2 (0x2)
mmio ffffffffffffffff/0000000000000020
dev: serial-mm, id ""
gpio-out "sysbus-irq" 1
regshift = 2 (0x2)
endianness = 2 (0x2)
mmio ffffffffffffffff/0000000000000020
dev: serial-mm, id ""
gpio-out "sysbus-irq" 1
regshift = 2 (0x2)
endianness = 2 (0x2)
mmio ffffffffffffffff/0000000000000020
dev: serial-mm, id ""
gpio-out "sysbus-irq" 1
regshift = 2 (0x2)
endianness = 2 (0x2)
mmio ffffffffffffffff/0000000000000020
dev: serial-mm, id ""
gpio-out "sysbus-irq" 1
regshift = 2 (0x2)
endianness = 2 (0x2)
mmio ffffffffffffffff/0000000000000020
dev: serial-mm, id ""
gpio-out "sysbus-irq" 1
regshift = 2 (0x2)
endianness = 2 (0x2)
mmio ffffffffffffffff/0000000000000020
dev: serial-mm, id ""
gpio-out "sysbus-irq" 1
regshift = 2 (0x2)
endianness = 2 (0x2)
mmio ffffffffffffffff/0000000000000020
dev: aspeed.scuio-ast2700, id ""
silicon-rev = 100729091 (0x6010103)
hw-strap1 = 1792 (0x700)
hw-strap2 = 0 (0x0)
hw-prot-key = 0 (0x0)
mmio ffffffffffffffff/0000000000001000
dev: aspeed.scu-ast2700, id ""
silicon-rev = 100729091 (0x6010103)
hw-strap1 = 2048 (0x800)
hw-strap2 = 0 (0x0)
hw-prot-key = 0 (0x0)
mmio ffffffffffffffff/0000000000001000
dev: aspeed.intcast2700-ioexp2, id ""
gpio-out "sysbus-irq" 10
gpio-in "" 2
mmio ffffffffffffffff/0000000000000400
dev: aspeed.intcast2700-ioexp1, id ""
gpio-out "sysbus-irq" 10
gpio-in "" 2
mmio ffffffffffffffff/0000000000000400
dev: aspeed.intcio-ast2700, id ""
gpio-out "sysbus-irq" 6
gpio-in "" 6
mmio ffffffffffffffff/0000000000000400
dev: aspeed.intc-ast2700, id ""
gpio-out "sysbus-irq" 10
gpio-in "" 1
mmio ffffffffffffffff/0000000000004000
dev: arm-gicv3, id ""
gpio-out "sysbus-irq" 24
gpio-in "" 384
num-cpu = 4 (0x4)
num-irq = 288 (0x120)
revision = 3 (0x3)
has-lpi = false
has-nmi = false
has-security-extensions = false
maintenance-interrupt-id = 0 (0x0)
force-8-bit-prio = false
redist-region-count = 4 (0x4)
sysmem = ""
first-cpu-index = 0 (0x0)
mmio ffffffffffffffff/0000000000010000
mmio ffffffffffffffff/0000000000080000
Cc: QOM/qdev maintainers
Cédric Le Goater <clg@kaod.org> writes:
> Hello,
>
> On 1/19/26 15:25, Markus Armbruster wrote:
>> Cédric Le Goater <clg@kaod.org> writes:
>>
>>> On 1/15/26 20:47, Philippe Mathieu-Daudé wrote:
>>>> Hi,
>>>> Cc'ing Markus.
>>>> On 12/1/26 09:30, Kane Chen via qemu development wrote:
>>>>> From: Kane-Chen-AS <kane_chen@aspeedtech.com>
>>>>>
>>>>> Currently, the Aspeed I2C controller uses a static naming convention
>>>>> for its buses (e.g., "aspeed.i2c.bus.0"). This approach leads to
>>>>> object name conflicts in machine models that incorporate multiple I2C
>>>>> controllers, such as an Aspeed SoC paired with an external IO expander
>>>>> or a co-processor like the AST1700.
>>>>>
>>>> Is this a side-effect of Problem 4: 'The /machine/unattached/ orphanage'
>>>> described here?
>>>> https://lore.kernel.org/qemu-devel/87o7d1i7ky.fsf@pond.sub.org/
No, but ...
>>>> This problem isn't specific to I2C nor Aspeed.
... yes, indeed. Details below.
>>> See the discussion here :
>>>
>>> https://lore.kernel.org/qemu-devel/006fa26f-6b84-4e82-b6e1-7d1353579441@kaod.org/
>>>
>>> The Aspeed SoC has 3*16 I2C buses attached on 3 different I2C
>>> controllers plus the I2C/I3C buses. We need to find a way to
>>> distinguish these groups at the QEMU machine level to be able
>>> to add devices on the right bus when using the command line.
>>>
>>> Suggestions welcome !
>>
>> Please show me how to start a QEMU with the 48 I2C mentioned above,
>> complete with output of "info qtree".
>
> Clone
>
> https://github.com/legoater/qemu/commits/aspeed-11.0
>
> Download
>
> https://github.com/AspeedTech-BMC/openbmc/releases/download/v09.08/ast2700-default-obmc.tar.gz
>
> And run :
>
> qemu-system-aarch64 -M ast2700a1-evb -m 8G -smp 4 -net nic,macaddr=,netdev=net0 -netdev user,id=net0,hostfwd=::2207-:22 -drive file=path/to/ast2700-default/image-bmc,format=raw,if=mtd -nographic -serial mon:stdio -snapshot
>
> Today, to attach an I2C device on one of the Aspeed SoC I2C buses :
>
> -device tmp105,bus=aspeed.i2c.bus.1,address=0x4d,id=tmp-test
>
> The Aspeed SoC I2C bus names follow the "aspeed.i2c.bus.X" format.
> This is the model typename. The 2 new IO expander models attached
> to the Aspeed SoC have an extra 16 I2C buses each. These buses use
> an "ioexpX.Y" name, as proposed in the aspeed-next branch.
>
> Attaching a device to one of the IO expanders I2C buses would be :
>
> -device tmp105,bus=ioexp0.1,address=0x4d,id=tmp-test
>
> See the qtree below.
Thank you!
Machine ast2700a1-evb has QOM objects
/machine/soc/i2c/ (aspeed.i2c-ast2700)
/bus[N] (aspeed.i2c.bus) for N in 0..15
/aspeed.i2c.bus.N (i2c-bus)
in both master and aspeed-11.0.
Object aspeed.i2c-ast2700 is a sysbus device that contains 16
aspeed.i2c.bus objects as children bus[N] for N in 0..15. Each object
has a property "bus-id" with value N.
Object aspeed.i2c.bus is a sysbus device that contains an i2c-bus object
as child aspeed.i2c.bus.N.
Aside: why parent TYPE_SYS_BUS_DEVICE, and not TYPE_DEVICE? It doesn't
actually plug into a sysbus...
Object i2c-bus is a qbus.
In master, object aspeed.i2c.bus computes the child name by appending .N
to its own type name TYPE_ASPEED_I2C_BUS.
In aspeed-11.0, it takes it from its property "bus-name". The property
is set by its QOM parent aspeed.i2c-ast2700, and computed by appending
.N to the value of its property "bus-label". It defaults the property
to TYPE_ASPEED_I2C_BUS.
Since nothing sets this property in this case, we get the same child
name.
aspeed-11.0 additionally has QOM objects
/machine/soc/ioexp[M] (aspeed.ast1700) for M in 0..1
/ioexp-i2c[0] (aspeed.i2c-ast2700)
/bus[N] (aspeed.i2c.bus) for N in 0..15
/ioexpM.N (i2c-bus)
Object aspeed.ast1700 is a sysbus device that contains an
aspeed.i2c-ast2700 as child "ioexp-i2c[0]". It has a property
"board-idx" with value M.
Aside: we only ever create one aspeed.i2c-ast2700 child. Why [0]?
Aside^2: I tried to strangle the "[*]" feature in the crib, but failed.
Has been a minor thorn in my side ever since.
aspeed.ast1700 set its child's (aspeed.i2c-ast2700) property "bus-label"
to "ioexpM". This makes the child set the grandchild's (aspeed.i2c.bus)
property "bus-name" to "ioexpM.N", which makes the grandchild name the
great-grandchild (i2c-bus) "ioexpM.N".
This naming business is complicated, and I had a hard time ferreting it
out. As far as I can tell, it's all in service of -device bus=...
Let's examine how that works.
We want to be able to plug i2c devices into any of these 48 i2c buses
with -device / device_add. To do that, we need to select a bus with the
"bus" argument.
In a world saner than the one we live in, the value of "bus" would be a
QOM path or qdev ID, where qdev ID is shorthand for the QOM path
/machine/peripheral/ID.
For instance, the first i2c bus could then be selected with absolute QOM
path "/machine/soc/i2c/bus[0]" or partial QOM paths "soc/i2c/bus[0]" or
"i2c/bus[0]". Partial QOM paths are a convenience feature that is
virtually unknown (and possibly ill-advised): you can omit leading path
components as long as there's no ambiguity.
However, in the world we live in, the value of bus is not a QOM path,
it's a path in the qtree. Why? qdev and -device / device_add predate
QOM.
If the path starts with "/", it's anchored at the main system bus.
Else, it's anchored at a bus whose name is the first path component. If
there's more than one such bus, we pick the first one we find. This is
a misfeature.
Remaining path components, if any, pick a path in the qtree from that
anchor towards leaves. Note that the child of a qbus is always a qdev,
and the child of a qdev always a qbus.
This must ultimately resolve to a qbus of the appropriate type.
Picking a qdev child of a qbus works like this:
* If a child with a (user-specified) qdev ID equal to the path component
exists, pick it. Since qdev IDs are unique, there can only be one.
* Else, if children whose QOM type name equals the path component
exists, pick the first one.
* Else, if children whose qdev alias equals the path component exists,
pick the first one.
Picking the first one is again a misfeature.
Picking a qbus child is simpler: we pick the first child whose bus name
equals the path component.
Bus names are defined as follows:
* Whatever creates the bus may set its name.
* Else, if the qbus's parent qdev has an ID, the bus name is ID.N, where
N counts up from 0 within that qdev.
* Else, the bus name is TYPE.N, where TYPE is the parent qdev's QOM type
name, and N counts up from 0 within that bus class.
The only case where this is actually works is picking the N-th bus child
provided by a qdev with an ID: use bus=ID.N (a partial tree path of just
one component). Anything else is unfit for purpose, except in special
cases, e.g. when the machine can have just one device of a certain type.
This mess is harmless for user-created devices: just specify the ID.
It's awful for onboard devices, which cannot have an ID.
This is a qdev design flaw. It's not specific to I2C or Aspeed, as
Philippe suspected.
To illustrate it further, let's have a look at the qtree of machine
ast2700a1-evb. Output of "info qtree" in master:
bus: main-system-bus
type System
[...]
dev: aspeed.i2c.bus, id "" for N in 0..15
[...]
bus: aspeed.i2c.bus.N
type i2c-bus
[...]
In aspeed-11.0, we additionally have
dev: aspeed.i2c.bus, id "" for M in 0..1, N in 0..15
[...]
bus: ioexpM.N
type i2c-bus
[...]
The i2c-buses all have unique names: aspeed.i2c-bus.N and ioexpM.N. We
can point to any of them with a partial qtree path of just one
component: bus=NAME where NAME is one of these unique names works, and
there is no ambiguity.
The buses have unique names only because device code takes pains to make
them configurable by parent devices, and the parent devices cooperate to
configure them so the resulting bus names are unique.
This is a lot of complexity to work around this qdev design flaw for
just one special instance.
Can we instead remedy the design flaw once and for all?
Here't the obvious stupid idea: give -device / device_add the means to
pick a bus by QOM path.
Thoughts?
On 1/20/26 11:36, Markus Armbruster wrote:
> Cc: QOM/qdev maintainers
>
> Cédric Le Goater <clg@kaod.org> writes:
>
>> Hello,
>>
>> On 1/19/26 15:25, Markus Armbruster wrote:
>>> Cédric Le Goater <clg@kaod.org> writes:
>>>
>>>> On 1/15/26 20:47, Philippe Mathieu-Daudé wrote:
>>>>> Hi,
>>>>> Cc'ing Markus.
>>>>> On 12/1/26 09:30, Kane Chen via qemu development wrote:
>>>>>> From: Kane-Chen-AS <kane_chen@aspeedtech.com>
>>>>>>
>>>>>> Currently, the Aspeed I2C controller uses a static naming convention
>>>>>> for its buses (e.g., "aspeed.i2c.bus.0"). This approach leads to
>>>>>> object name conflicts in machine models that incorporate multiple I2C
>>>>>> controllers, such as an Aspeed SoC paired with an external IO expander
>>>>>> or a co-processor like the AST1700.
>>>>>>
>>>>> Is this a side-effect of Problem 4: 'The /machine/unattached/ orphanage'
>>>>> described here?
>>>>> https://lore.kernel.org/qemu-devel/87o7d1i7ky.fsf@pond.sub.org/
>
> No, but ...
>
>>>>> This problem isn't specific to I2C nor Aspeed.
>
> ... yes, indeed. Details below.
>
>>>> See the discussion here :
>>>>
>>>> https://lore.kernel.org/qemu-devel/006fa26f-6b84-4e82-b6e1-7d1353579441@kaod.org/
>>>>
>>>> The Aspeed SoC has 3*16 I2C buses attached on 3 different I2C
>>>> controllers plus the I2C/I3C buses. We need to find a way to
>>>> distinguish these groups at the QEMU machine level to be able
>>>> to add devices on the right bus when using the command line.
>>>>
>>>> Suggestions welcome !
>>>
>>> Please show me how to start a QEMU with the 48 I2C mentioned above,
>>> complete with output of "info qtree".
>>
>> Clone
>>
>> https://github.com/legoater/qemu/commits/aspeed-11.0
>>
>> Download
>>
>> https://github.com/AspeedTech-BMC/openbmc/releases/download/v09.08/ast2700-default-obmc.tar.gz
>>
>> And run :
>>
>> qemu-system-aarch64 -M ast2700a1-evb -m 8G -smp 4 -net nic,macaddr=,netdev=net0 -netdev user,id=net0,hostfwd=::2207-:22 -drive file=path/to/ast2700-default/image-bmc,format=raw,if=mtd -nographic -serial mon:stdio -snapshot
>>
>> Today, to attach an I2C device on one of the Aspeed SoC I2C buses :
>>
>> -device tmp105,bus=aspeed.i2c.bus.1,address=0x4d,id=tmp-test
>>
>> The Aspeed SoC I2C bus names follow the "aspeed.i2c.bus.X" format.
>> This is the model typename. The 2 new IO expander models attached
>> to the Aspeed SoC have an extra 16 I2C buses each. These buses use
>> an "ioexpX.Y" name, as proposed in the aspeed-next branch.
>>
>> Attaching a device to one of the IO expanders I2C buses would be :
>>
>> -device tmp105,bus=ioexp0.1,address=0x4d,id=tmp-test
>>
>> See the qtree below.
>
> Thank you!
Thank you for taking the time of analyzing the code and history.
>
> Machine ast2700a1-evb has QOM objects
>
> /machine/soc/i2c/ (aspeed.i2c-ast2700)
> /bus[N] (aspeed.i2c.bus) for N in 0..15
> /aspeed.i2c.bus.N (i2c-bus)
>
> in both master and aspeed-11.0.
Yes, that doesn't change because I would prefer not to break the current
user interface. The "i2c.X" bus name would have been a better choice.
I didn't anticipated that 10y ago when I proposed this model.
> Object aspeed.i2c-ast2700 is a sysbus device that contains 16
> aspeed.i2c.bus objects as children bus[N] for N in 0..15. Each object
> has a property "bus-id" with value N.
>
> Object aspeed.i2c.bus is a sysbus device that contains an i2c-bus object
> as child aspeed.i2c.bus.N.
>
> Aside: why parent TYPE_SYS_BUS_DEVICE, and not TYPE_DEVICE? It doesn't
> actually plug into a sysbus...
The AspeedI2CBus model has a couple of MRs and an IRQ. I guess that's why.
> Object i2c-bus is a qbus.
>
> In master, object aspeed.i2c.bus computes the child name by appending .N
> to its own type name TYPE_ASPEED_I2C_BUS.
>
> In aspeed-11.0, it takes it from its property "bus-name". The property
> is set by its QOM parent aspeed.i2c-ast2700, and computed by appending
> .N to the value of its property "bus-label". It defaults the property
> to TYPE_ASPEED_I2C_BUS.
>
> Since nothing sets this property in this case, we get the same child
> name.
>
> aspeed-11.0 additionally has QOM objects
>
> /machine/soc/ioexp[M] (aspeed.ast1700) for M in 0..1
> /ioexp-i2c[0] (aspeed.i2c-ast2700)
> /bus[N] (aspeed.i2c.bus) for N in 0..15
> /ioexpM.N (i2c-bus)
>
> Object aspeed.ast1700 is a sysbus device that contains an
> aspeed.i2c-ast2700 as child "ioexp-i2c[0]". It has a property
> "board-idx" with value M.
>
> Aside: we only ever create one aspeed.i2c-ast2700 child. Why [0]?
Right. We can drop [*] in aspeed_ast1700_instance_init() - PATCH 15.
> Aside^2: I tried to strangle the "[*]" feature in the crib, but failed.
> Has been a minor thorn in my side ever since.
>
> aspeed.ast1700 set its child's (aspeed.i2c-ast2700) property "bus-label"
> to "ioexpM". This makes the child set the grandchild's (aspeed.i2c.bus)
> property "bus-name" to "ioexpM.N", which makes the grandchild name the
> great-grandchild (i2c-bus) "ioexpM.N".
>
> This naming business is complicated, and I had a hard time ferreting it
> out. As far as I can tell, it's all in service of -device bus=...
yes.
That's why I regret not letting QEMU taking care of the naming with :
s->bus = i2c_init_bus(dev, NULL);
This would break the user interface though. This is still an option.
> Let's examine how that works.
>
> We want to be able to plug i2c devices into any of these 48 i2c buses
> with -device / device_add. To do that, we need to select a bus with the
> "bus" argument.
>
> In a world saner than the one we live in, the value of "bus" would be a
> QOM path or qdev ID, where qdev ID is shorthand for the QOM path
> /machine/peripheral/ID.
>
> For instance, the first i2c bus could then be selected with absolute QOM
> path "/machine/soc/i2c/bus[0]" or partial QOM paths "soc/i2c/bus[0]" or
> "i2c/bus[0]". Partial QOM paths are a convenience feature that is
> virtually unknown (and possibly ill-advised): you can omit leading path
> components as long as there's no ambiguity.
>
> However, in the world we live in, the value of bus is not a QOM path,
> it's a path in the qtree. Why? qdev and -device / device_add predate
> QOM.
>
> If the path starts with "/", it's anchored at the main system bus.
>
> Else, it's anchored at a bus whose name is the first path component. If
> there's more than one such bus, we pick the first one we find. This is
> a misfeature.
>
> Remaining path components, if any, pick a path in the qtree from that
> anchor towards leaves. Note that the child of a qbus is always a qdev,
> and the child of a qdev always a qbus.
>
> This must ultimately resolve to a qbus of the appropriate type.
>
> Picking a qdev child of a qbus works like this:
>
> * If a child with a (user-specified) qdev ID equal to the path component
> exists, pick it. Since qdev IDs are unique, there can only be one.
>
> * Else, if children whose QOM type name equals the path component
> exists, pick the first one.
>
> * Else, if children whose qdev alias equals the path component exists,
> pick the first one.
>
> Picking the first one is again a misfeature.
>
> Picking a qbus child is simpler: we pick the first child whose bus name
> equals the path component.
>
> Bus names are defined as follows:
>
> * Whatever creates the bus may set its name.
>
> * Else, if the qbus's parent qdev has an ID, the bus name is ID.N, where
> N counts up from 0 within that qdev.
>
> * Else, the bus name is TYPE.N, where TYPE is the parent qdev's QOM type
> name, and N counts up from 0 within that bus class.
>
> The only case where this is actually works is picking the N-th bus child
> provided by a qdev with an ID: use bus=ID.N (a partial tree path of just
> one component). Anything else is unfit for purpose, except in special
> cases, e.g. when the machine can have just one device of a certain type.
>
> This mess is harmless for user-created devices: just specify the ID.
> It's awful for onboard devices, which cannot have an ID.
>
> This is a qdev design flaw. It's not specific to I2C or Aspeed, as
> Philippe suspected.
>
> To illustrate it further, let's have a look at the qtree of machine
> ast2700a1-evb. Output of "info qtree" in master:
>
> bus: main-system-bus
> type System
> [...]
> dev: aspeed.i2c.bus, id "" for N in 0..15
> [...]
> bus: aspeed.i2c.bus.N
> type i2c-bus
> [...]
>
> In aspeed-11.0, we additionally have
>
> dev: aspeed.i2c.bus, id "" for M in 0..1, N in 0..15
> [...]
> bus: ioexpM.N
> type i2c-bus
> [...]
>
> The i2c-buses all have unique names: aspeed.i2c-bus.N and ioexpM.N. We
> can point to any of them with a partial qtree path of just one
> component: bus=NAME where NAME is one of these unique names works, and
> there is no ambiguity.
>
> The buses have unique names only because device code takes pains to make
> them configurable by parent devices, and the parent devices cooperate to
> configure them so the resulting bus names are unique.
>
> This is a lot of complexity to work around this qdev design flaw for
> just one special instance.
>
> Can we instead remedy the design flaw once and for all?
>
> Here't the obvious stupid idea: give -device / device_add the means to
> pick a bus by QOM path.
>
> Thoughts?
>
Could we support both methods ? I mean looking up the bus by the
qtree name and by the QOM path ?
Thanks,
C.
Cédric Le Goater <clg@kaod.org> writes: > On 1/20/26 11:36, Markus Armbruster wrote: >> Cc: QOM/qdev maintainers >> Cédric Le Goater <clg@kaod.org> writes: >> >>> Hello, >>> >>> On 1/19/26 15:25, Markus Armbruster wrote: >>>> Cédric Le Goater <clg@kaod.org> writes: >>>> >>>>> On 1/15/26 20:47, Philippe Mathieu-Daudé wrote: >>>>>> Hi, >>>>>> Cc'ing Markus. >>>>>> On 12/1/26 09:30, Kane Chen via qemu development wrote: >>>>>>> From: Kane-Chen-AS <kane_chen@aspeedtech.com> >>>>>>> >>>>>>> Currently, the Aspeed I2C controller uses a static naming convention >>>>>>> for its buses (e.g., "aspeed.i2c.bus.0"). This approach leads to >>>>>>> object name conflicts in machine models that incorporate multiple I2C >>>>>>> controllers, such as an Aspeed SoC paired with an external IO expander >>>>>>> or a co-processor like the AST1700. >>>>>>> >>>>>> Is this a side-effect of Problem 4: 'The /machine/unattached/ orphanage' >>>>>> described here? >>>>>> https://lore.kernel.org/qemu-devel/87o7d1i7ky.fsf@pond.sub.org/ >> >> No, but ... >> >>>>>> This problem isn't specific to I2C nor Aspeed. >> >> ... yes, indeed. Details below. >> >>>>> See the discussion here : >>>>> >>>>> https://lore.kernel.org/qemu-devel/006fa26f-6b84-4e82-b6e1-7d1353579441@kaod.org/ >>>>> >>>>> The Aspeed SoC has 3*16 I2C buses attached on 3 different I2C >>>>> controllers plus the I2C/I3C buses. We need to find a way to >>>>> distinguish these groups at the QEMU machine level to be able >>>>> to add devices on the right bus when using the command line. >>>>> >>>>> Suggestions welcome ! >>>> >>>> Please show me how to start a QEMU with the 48 I2C mentioned above, >>>> complete with output of "info qtree". >>> >>> Clone >>> >>> https://github.com/legoater/qemu/commits/aspeed-11.0 >>> >>> Download >>> >>> https://github.com/AspeedTech-BMC/openbmc/releases/download/v09.08/ast2700-default-obmc.tar.gz >>> >>> And run : >>> >>> qemu-system-aarch64 -M ast2700a1-evb -m 8G -smp 4 -net nic,macaddr=,netdev=net0 -netdev user,id=net0,hostfwd=::2207-:22 -drive file=path/to/ast2700-default/image-bmc,format=raw,if=mtd -nographic -serial mon:stdio -snapshot >>> >>> Today, to attach an I2C device on one of the Aspeed SoC I2C buses : >>> >>> -device tmp105,bus=aspeed.i2c.bus.1,address=0x4d,id=tmp-test >>> >>> The Aspeed SoC I2C bus names follow the "aspeed.i2c.bus.X" format. >>> This is the model typename. The 2 new IO expander models attached >>> to the Aspeed SoC have an extra 16 I2C buses each. These buses use >>> an "ioexpX.Y" name, as proposed in the aspeed-next branch. >>> >>> Attaching a device to one of the IO expanders I2C buses would be : >>> >>> -device tmp105,bus=ioexp0.1,address=0x4d,id=tmp-test >>> >>> See the qtree below. >> >> Thank you! > > Thank you for taking the time of analyzing the code and history. > >> Machine ast2700a1-evb has QOM objects >> >> /machine/soc/i2c/ (aspeed.i2c-ast2700) >> /bus[N] (aspeed.i2c.bus) for N in 0..15 >> /aspeed.i2c.bus.N (i2c-bus) >> >> in both master and aspeed-11.0. > > Yes, that doesn't change because I would prefer not to break the current > user interface. The "i2c.X" bus name would have been a better choice. > I didn't anticipated that 10y ago when I proposed this model. We make mistakes, we learn :) >> Object aspeed.i2c-ast2700 is a sysbus device that contains 16 >> aspeed.i2c.bus objects as children bus[N] for N in 0..15. Each object >> has a property "bus-id" with value N. >> >> Object aspeed.i2c.bus is a sysbus device that contains an i2c-bus object >> as child aspeed.i2c.bus.N. >> >> Aside: why parent TYPE_SYS_BUS_DEVICE, and not TYPE_DEVICE? It doesn't >> actually plug into a sysbus... > > The AspeedI2CBus model has a couple of MRs and an IRQ. I guess that's why. Sysbus was a questionable idea from the start. Qdev was built around the design assumption "each device plugs into a bus provided by a device". This isn't not how real hardware works, but simplifications can be useful. However, this one broke down right away: most onboard devices and many other devices don't plug into a recognizable bus. To make the assumption work, Paul Brook invented the catch all "system bus". Various infrastructure was then tied to the system bus over time, because it needed to be tied to something, system bus is something, therefore it needed to be tied to the system bus. The design assumption is long gone. We still create system bus devices just to be able to use infrastructure. Blerch. End of digression. >> Object i2c-bus is a qbus. >> >> In master, object aspeed.i2c.bus computes the child name by appending .N >> to its own type name TYPE_ASPEED_I2C_BUS. >> >> In aspeed-11.0, it takes it from its property "bus-name". The property >> is set by its QOM parent aspeed.i2c-ast2700, and computed by appending >> .N to the value of its property "bus-label". It defaults the property >> to TYPE_ASPEED_I2C_BUS. >> >> Since nothing sets this property in this case, we get the same child >> name. >> >> aspeed-11.0 additionally has QOM objects >> >> /machine/soc/ioexp[M] (aspeed.ast1700) for M in 0..1 >> /ioexp-i2c[0] (aspeed.i2c-ast2700) >> /bus[N] (aspeed.i2c.bus) for N in 0..15 >> /ioexpM.N (i2c-bus) >> >> Object aspeed.ast1700 is a sysbus device that contains an >> aspeed.i2c-ast2700 as child "ioexp-i2c[0]". It has a property >> "board-idx" with value M. >> >> Aside: we only ever create one aspeed.i2c-ast2700 child. Why [0]? > > Right. We can drop [*] in aspeed_ast1700_instance_init() - PATCH 15. > >> Aside^2: I tried to strangle the "[*]" feature in the crib, but failed. >> Has been a minor thorn in my side ever since. >> >> aspeed.ast1700 set its child's (aspeed.i2c-ast2700) property "bus-label" >> to "ioexpM". This makes the child set the grandchild's (aspeed.i2c.bus) >> property "bus-name" to "ioexpM.N", which makes the grandchild name the >> great-grandchild (i2c-bus) "ioexpM.N". >> >> This naming business is complicated, and I had a hard time ferreting it >> out. As far as I can tell, it's all in service of -device bus=... > > yes. > > That's why I regret not letting QEMU taking care of the naming with : > > s->bus = i2c_init_bus(dev, NULL); > > This would break the user interface though. This is still an option. Since the devices providing these i2c buses have no qdev ID, these buses would then be named i2c.N, where N counts up from 0. I think. See "Bus names are defined as follows" below. Good enough? >> Let's examine how that works. >> >> We want to be able to plug i2c devices into any of these 48 i2c buses >> with -device / device_add. To do that, we need to select a bus with the >> "bus" argument. >> >> In a world saner than the one we live in, the value of "bus" would be a >> QOM path or qdev ID, where qdev ID is shorthand for the QOM path >> /machine/peripheral/ID. Nonsense. "QOM path or qdev ID" is how the @id argument of device_del and device_sync_config work. A qdev ID resolves to a qdev. Here, we need to resolve to a qbus. Instead, "QOM path or qbus ID". Except the concept "qbus ID" does not exist. All we have is qbus names, which aren't unique (we screwed that up). >> For instance, the first i2c bus could then be selected with absolute QOM >> path "/machine/soc/i2c/bus[0]" or partial QOM paths "soc/i2c/bus[0]" or >> "i2c/bus[0]". Partial QOM paths are a convenience feature that is >> virtually unknown (and possibly ill-advised): you can omit leading path >> components as long as there's no ambiguity. >> >> However, in the world we live in, the value of bus is not a QOM path, >> it's a path in the qtree. Why? qdev and -device / device_add predate >> QOM. >> >> If the path starts with "/", it's anchored at the main system bus. >> >> Else, it's anchored at a bus whose name is the first path component. If >> there's more than one such bus, we pick the first one we find. This is >> a misfeature. >> >> Remaining path components, if any, pick a path in the qtree from that >> anchor towards leaves. Note that the child of a qbus is always a qdev, >> and the child of a qdev always a qbus. >> >> This must ultimately resolve to a qbus of the appropriate type. >> >> Picking a qdev child of a qbus works like this: >> >> * If a child with a (user-specified) qdev ID equal to the path component >> exists, pick it. Since qdev IDs are unique, there can only be one. >> >> * Else, if children whose QOM type name equals the path component >> exists, pick the first one. >> >> * Else, if children whose qdev alias equals the path component exists, >> pick the first one. >> >> Picking the first one is again a misfeature. >> >> Picking a qbus child is simpler: we pick the first child whose bus name >> equals the path component. >> >> Bus names are defined as follows: >> >> * Whatever creates the bus may set its name. >> >> * Else, if the qbus's parent qdev has an ID, the bus name is ID.N, where >> N counts up from 0 within that qdev. >> >> * Else, the bus name is TYPE.N, where TYPE is the parent qdev's QOM type >> name, and N counts up from 0 within that bus class. The qbus's QOM type name, of course. >> The only case where this is actually works is picking the N-th bus child >> provided by a qdev with an ID: use bus=ID.N (a partial tree path of just >> one component). Anything else is unfit for purpose, except in special >> cases, e.g. when the machine can have just one device of a certain type. >> >> This mess is harmless for user-created devices: just specify the ID. >> It's awful for onboard devices, which cannot have an ID. >> >> This is a qdev design flaw. It's not specific to I2C or Aspeed, as >> Philippe suspected. >> >> To illustrate it further, let's have a look at the qtree of machine >> ast2700a1-evb. Output of "info qtree" in master: >> >> bus: main-system-bus >> type System >> [...] >> dev: aspeed.i2c.bus, id "" for N in 0..15 >> [...] >> bus: aspeed.i2c.bus.N >> type i2c-bus >> [...] >> >> In aspeed-11.0, we additionally have >> >> dev: aspeed.i2c.bus, id "" for M in 0..1, N in 0..15 >> [...] >> bus: ioexpM.N >> type i2c-bus >> [...] >> >> The i2c-buses all have unique names: aspeed.i2c-bus.N and ioexpM.N. We >> can point to any of them with a partial qtree path of just one >> component: bus=NAME where NAME is one of these unique names works, and >> there is no ambiguity. >> >> The buses have unique names only because device code takes pains to make >> them configurable by parent devices, and the parent devices cooperate to >> configure them so the resulting bus names are unique. >> >> This is a lot of complexity to work around this qdev design flaw for >> just one special instance. >> >> Can we instead remedy the design flaw once and for all? >> >> Here't the obvious stupid idea: give -device / device_add the means to >> pick a bus by QOM path. >> >> Thoughts? > > Could we support both methods ? I mean looking up the bus by the > qtree name and by the QOM path ? We can't just change "bus". Management applications and human users rely on it. Except we might be able to break aspects that aren't actually used in anger. Is anyone using '/' in qtree paths in anger? I sure hope nobody does, because that way is madness. But it's hard to be reasonably sure. If we can break '/' in the value of "bus", we could overload "bus": make it a QOM path or a qbus ID, similar to how device_del's @id is a QOM path or a qdev ID. We'd have to define "qbus ID". Instead, we could perhaps add an argument "parent" to specify the QOM parent object, mutually exclusive with "bus". For devices that plug into a certain kind of bus, the parent object must be an instance of that bus. > Thanks, > > C. You're welcome!
On 1/22/26 14:02, Markus Armbruster wrote: > Cédric Le Goater <clg@kaod.org> writes: > >> On 1/20/26 11:36, Markus Armbruster wrote: >>> Cc: QOM/qdev maintainers >>> Cédric Le Goater <clg@kaod.org> writes: >>> >>>> Hello, >>>> >>>> On 1/19/26 15:25, Markus Armbruster wrote: >>>>> Cédric Le Goater <clg@kaod.org> writes: >>>>> >>>>>> On 1/15/26 20:47, Philippe Mathieu-Daudé wrote: >>>>>>> Hi, >>>>>>> Cc'ing Markus. >>>>>>> On 12/1/26 09:30, Kane Chen via qemu development wrote: >>>>>>>> From: Kane-Chen-AS <kane_chen@aspeedtech.com> >>>>>>>> >>>>>>>> Currently, the Aspeed I2C controller uses a static naming convention >>>>>>>> for its buses (e.g., "aspeed.i2c.bus.0"). This approach leads to >>>>>>>> object name conflicts in machine models that incorporate multiple I2C >>>>>>>> controllers, such as an Aspeed SoC paired with an external IO expander >>>>>>>> or a co-processor like the AST1700. >>>>>>>> >>>>>>> Is this a side-effect of Problem 4: 'The /machine/unattached/ orphanage' >>>>>>> described here? >>>>>>> https://lore.kernel.org/qemu-devel/87o7d1i7ky.fsf@pond.sub.org/ >>> >>> No, but ... >>> >>>>>>> This problem isn't specific to I2C nor Aspeed. >>> >>> ... yes, indeed. Details below. >>> >>>>>> See the discussion here : >>>>>> >>>>>> https://lore.kernel.org/qemu-devel/006fa26f-6b84-4e82-b6e1-7d1353579441@kaod.org/ >>>>>> >>>>>> The Aspeed SoC has 3*16 I2C buses attached on 3 different I2C >>>>>> controllers plus the I2C/I3C buses. We need to find a way to >>>>>> distinguish these groups at the QEMU machine level to be able >>>>>> to add devices on the right bus when using the command line. >>>>>> >>>>>> Suggestions welcome ! >>>>> >>>>> Please show me how to start a QEMU with the 48 I2C mentioned above, >>>>> complete with output of "info qtree". >>>> >>>> Clone >>>> >>>> https://github.com/legoater/qemu/commits/aspeed-11.0 >>>> >>>> Download >>>> >>>> https://github.com/AspeedTech-BMC/openbmc/releases/download/v09.08/ast2700-default-obmc.tar.gz >>>> >>>> And run : >>>> >>>> qemu-system-aarch64 -M ast2700a1-evb -m 8G -smp 4 -net nic,macaddr=,netdev=net0 -netdev user,id=net0,hostfwd=::2207-:22 -drive file=path/to/ast2700-default/image-bmc,format=raw,if=mtd -nographic -serial mon:stdio -snapshot >>>> >>>> Today, to attach an I2C device on one of the Aspeed SoC I2C buses : >>>> >>>> -device tmp105,bus=aspeed.i2c.bus.1,address=0x4d,id=tmp-test >>>> >>>> The Aspeed SoC I2C bus names follow the "aspeed.i2c.bus.X" format. >>>> This is the model typename. The 2 new IO expander models attached >>>> to the Aspeed SoC have an extra 16 I2C buses each. These buses use >>>> an "ioexpX.Y" name, as proposed in the aspeed-next branch. >>>> >>>> Attaching a device to one of the IO expanders I2C buses would be : >>>> >>>> -device tmp105,bus=ioexp0.1,address=0x4d,id=tmp-test >>>> >>>> See the qtree below. >>> >>> Thank you! >> >> Thank you for taking the time of analyzing the code and history. >> >>> Machine ast2700a1-evb has QOM objects >>> >>> /machine/soc/i2c/ (aspeed.i2c-ast2700) >>> /bus[N] (aspeed.i2c.bus) for N in 0..15 >>> /aspeed.i2c.bus.N (i2c-bus) >>> >>> in both master and aspeed-11.0. >> >> Yes, that doesn't change because I would prefer not to break the current >> user interface. The "i2c.X" bus name would have been a better choice. >> I didn't anticipated that 10y ago when I proposed this model. > > We make mistakes, we learn :) > >>> Object aspeed.i2c-ast2700 is a sysbus device that contains 16 >>> aspeed.i2c.bus objects as children bus[N] for N in 0..15. Each object >>> has a property "bus-id" with value N. >>> >>> Object aspeed.i2c.bus is a sysbus device that contains an i2c-bus object >>> as child aspeed.i2c.bus.N. >>> >>> Aside: why parent TYPE_SYS_BUS_DEVICE, and not TYPE_DEVICE? It doesn't >>> actually plug into a sysbus... >> >> The AspeedI2CBus model has a couple of MRs and an IRQ. I guess that's why. > > Sysbus was a questionable idea from the start. > > Qdev was built around the design assumption "each device plugs into a > bus provided by a device". This isn't not how real hardware works, but > simplifications can be useful. However, this one broke down right away: > most onboard devices and many other devices don't plug into a > recognizable bus. To make the assumption work, Paul Brook invented the > catch all "system bus". Various infrastructure was then tied to the > system bus over time, because it needed to be tied to something, system > bus is something, therefore it needed to be tied to the system bus. > > The design assumption is long gone. We still create system bus devices > just to be able to use infrastructure. Blerch. > > End of digression. > >>> Object i2c-bus is a qbus. >>> >>> In master, object aspeed.i2c.bus computes the child name by appending .N >>> to its own type name TYPE_ASPEED_I2C_BUS. >>> >>> In aspeed-11.0, it takes it from its property "bus-name". The property >>> is set by its QOM parent aspeed.i2c-ast2700, and computed by appending >>> .N to the value of its property "bus-label". It defaults the property >>> to TYPE_ASPEED_I2C_BUS. >>> >>> Since nothing sets this property in this case, we get the same child >>> name. >>> >>> aspeed-11.0 additionally has QOM objects >>> >>> /machine/soc/ioexp[M] (aspeed.ast1700) for M in 0..1 >>> /ioexp-i2c[0] (aspeed.i2c-ast2700) >>> /bus[N] (aspeed.i2c.bus) for N in 0..15 >>> /ioexpM.N (i2c-bus) >>> >>> Object aspeed.ast1700 is a sysbus device that contains an >>> aspeed.i2c-ast2700 as child "ioexp-i2c[0]". It has a property >>> "board-idx" with value M. >>> >>> Aside: we only ever create one aspeed.i2c-ast2700 child. Why [0]? >> >> Right. We can drop [*] in aspeed_ast1700_instance_init() - PATCH 15. >> >>> Aside^2: I tried to strangle the "[*]" feature in the crib, but failed. >>> Has been a minor thorn in my side ever since. >>> >>> aspeed.ast1700 set its child's (aspeed.i2c-ast2700) property "bus-label" >>> to "ioexpM". This makes the child set the grandchild's (aspeed.i2c.bus) >>> property "bus-name" to "ioexpM.N", which makes the grandchild name the >>> great-grandchild (i2c-bus) "ioexpM.N". >>> >>> This naming business is complicated, and I had a hard time ferreting it >>> out. As far as I can tell, it's all in service of -device bus=... >> >> yes. >> >> That's why I regret not letting QEMU taking care of the naming with : >> >> s->bus = i2c_init_bus(dev, NULL); >> >> This would break the user interface though. This is still an option. > > Since the devices providing these i2c buses have no qdev ID, these buses > would then be named i2c.N, where N counts up from 0. I think. See "Bus > names are defined as follows" below. > > Good enough? Good enough to avoid the bus naming conflict, not good enough to easily identify a bus in the machine topology and it's also breaking the user interface ... too many cons to be a good choice. > >>> Let's examine how that works. >>> >>> We want to be able to plug i2c devices into any of these 48 i2c buses >>> with -device / device_add. To do that, we need to select a bus with the >>> "bus" argument. >>> >>> In a world saner than the one we live in, the value of "bus" would be a >>> QOM path or qdev ID, where qdev ID is shorthand for the QOM path >>> /machine/peripheral/ID. > > Nonsense. > > "QOM path or qdev ID" is how the @id argument of device_del and > device_sync_config work. A qdev ID resolves to a qdev. Here, we need > to resolve to a qbus. > > Instead, "QOM path or qbus ID". Except the concept "qbus ID" does not > exist. All we have is qbus names, which aren't unique (we screwed that > up). > >>> For instance, the first i2c bus could then be selected with absolute QOM >>> path "/machine/soc/i2c/bus[0]" or partial QOM paths "soc/i2c/bus[0]" or >>> "i2c/bus[0]". Partial QOM paths are a convenience feature that is >>> virtually unknown (and possibly ill-advised): you can omit leading path >>> components as long as there's no ambiguity. >>> >>> However, in the world we live in, the value of bus is not a QOM path, >>> it's a path in the qtree. Why? qdev and -device / device_add predate >>> QOM. >>> >>> If the path starts with "/", it's anchored at the main system bus. >>> >>> Else, it's anchored at a bus whose name is the first path component. If >>> there's more than one such bus, we pick the first one we find. This is >>> a misfeature. >>> >>> Remaining path components, if any, pick a path in the qtree from that >>> anchor towards leaves. Note that the child of a qbus is always a qdev, >>> and the child of a qdev always a qbus. >>> >>> This must ultimately resolve to a qbus of the appropriate type. >>> >>> Picking a qdev child of a qbus works like this: >>> >>> * If a child with a (user-specified) qdev ID equal to the path component >>> exists, pick it. Since qdev IDs are unique, there can only be one. >>> >>> * Else, if children whose QOM type name equals the path component >>> exists, pick the first one. >>> >>> * Else, if children whose qdev alias equals the path component exists, >>> pick the first one. >>> >>> Picking the first one is again a misfeature. >>> >>> Picking a qbus child is simpler: we pick the first child whose bus name >>> equals the path component. >>> >>> Bus names are defined as follows: >>> >>> * Whatever creates the bus may set its name. >>> >>> * Else, if the qbus's parent qdev has an ID, the bus name is ID.N, where >>> N counts up from 0 within that qdev. >>> >>> * Else, the bus name is TYPE.N, where TYPE is the parent qdev's QOM type >>> name, and N counts up from 0 within that bus class. > > The qbus's QOM type name, of course. > >>> The only case where this is actually works is picking the N-th bus child >>> provided by a qdev with an ID: use bus=ID.N (a partial tree path of just >>> one component). Anything else is unfit for purpose, except in special >>> cases, e.g. when the machine can have just one device of a certain type. >>> >>> This mess is harmless for user-created devices: just specify the ID. >>> It's awful for onboard devices, which cannot have an ID. >>> >>> This is a qdev design flaw. It's not specific to I2C or Aspeed, as >>> Philippe suspected. >>> >>> To illustrate it further, let's have a look at the qtree of machine >>> ast2700a1-evb. Output of "info qtree" in master: >>> >>> bus: main-system-bus >>> type System >>> [...] >>> dev: aspeed.i2c.bus, id "" for N in 0..15 >>> [...] >>> bus: aspeed.i2c.bus.N >>> type i2c-bus >>> [...] >>> >>> In aspeed-11.0, we additionally have >>> >>> dev: aspeed.i2c.bus, id "" for M in 0..1, N in 0..15 >>> [...] >>> bus: ioexpM.N >>> type i2c-bus >>> [...] >>> >>> The i2c-buses all have unique names: aspeed.i2c-bus.N and ioexpM.N. We >>> can point to any of them with a partial qtree path of just one >>> component: bus=NAME where NAME is one of these unique names works, and >>> there is no ambiguity. >>> >>> The buses have unique names only because device code takes pains to make >>> them configurable by parent devices, and the parent devices cooperate to >>> configure them so the resulting bus names are unique. >>> >>> This is a lot of complexity to work around this qdev design flaw for >>> just one special instance. >>> >>> Can we instead remedy the design flaw once and for all? >>> >>> Here't the obvious stupid idea: give -device / device_add the means to >>> pick a bus by QOM path. >>> >>> Thoughts? >> >> Could we support both methods ? I mean looking up the bus by the >> qtree name and by the QOM path ? > > We can't just change "bus". Management applications and human users > rely on it. > > Except we might be able to break aspects that aren't actually used in > anger. Is anyone using '/' in qtree paths in anger? I sure hope nobody > does, because that way is madness. But it's hard to be reasonably sure. Could we add a prefix to the bus name argument to signify a change of namespace for the lookup ? like 'qom:' or 'machine:' ? Thanks ! C. > If we can break '/' in the value of "bus", we could overload "bus": make > it a QOM path or a qbus ID, similar to how device_del's @id is a QOM > path or a qdev ID. We'd have to define "qbus ID". > > Instead, we could perhaps add an argument "parent" to specify the QOM > parent object, mutually exclusive with "bus". For devices that plug > into a certain kind of bus, the parent object must be an instance of > that bus. > >> Thanks, >> >> C. > > You're welcome! >
Cédric Le Goater <clg@kaod.org> writes: > On 1/22/26 14:02, Markus Armbruster wrote: >> Cédric Le Goater <clg@kaod.org> writes: >> >>> On 1/20/26 11:36, Markus Armbruster wrote: >>>> Cc: QOM/qdev maintainers >>>> Cédric Le Goater <clg@kaod.org> writes: >>>> >>>>> Hello, >>>>> >>>>> On 1/19/26 15:25, Markus Armbruster wrote: >>>>>> Cédric Le Goater <clg@kaod.org> writes: >>>>>> >>>>>>> On 1/15/26 20:47, Philippe Mathieu-Daudé wrote: >>>>>>>> Hi, >>>>>>>> Cc'ing Markus. >>>>>>>> On 12/1/26 09:30, Kane Chen via qemu development wrote: >>>>>>>>> From: Kane-Chen-AS <kane_chen@aspeedtech.com> >>>>>>>>> >>>>>>>>> Currently, the Aspeed I2C controller uses a static naming convention >>>>>>>>> for its buses (e.g., "aspeed.i2c.bus.0"). This approach leads to >>>>>>>>> object name conflicts in machine models that incorporate multiple I2C >>>>>>>>> controllers, such as an Aspeed SoC paired with an external IO expander >>>>>>>>> or a co-processor like the AST1700. >>>>>>>>> >>>>>>>> Is this a side-effect of Problem 4: 'The /machine/unattached/ orphanage' >>>>>>>> described here? >>>>>>>> https://lore.kernel.org/qemu-devel/87o7d1i7ky.fsf@pond.sub.org/ >>>> >>>> No, but ... >>>> >>>>>>>> This problem isn't specific to I2C nor Aspeed. >>>> >>>> ... yes, indeed. Details below. >>>> >>>>>>> See the discussion here : >>>>>>> >>>>>>> https://lore.kernel.org/qemu-devel/006fa26f-6b84-4e82-b6e1-7d1353579441@kaod.org/ >>>>>>> >>>>>>> The Aspeed SoC has 3*16 I2C buses attached on 3 different I2C >>>>>>> controllers plus the I2C/I3C buses. We need to find a way to >>>>>>> distinguish these groups at the QEMU machine level to be able >>>>>>> to add devices on the right bus when using the command line. >>>>>>> >>>>>>> Suggestions welcome ! >>>>>> >>>>>> Please show me how to start a QEMU with the 48 I2C mentioned above, >>>>>> complete with output of "info qtree". >>>>> >>>>> Clone >>>>> >>>>> https://github.com/legoater/qemu/commits/aspeed-11.0 >>>>> >>>>> Download >>>>> >>>>> https://github.com/AspeedTech-BMC/openbmc/releases/download/v09.08/ast2700-default-obmc.tar.gz >>>>> >>>>> And run : >>>>> >>>>> qemu-system-aarch64 -M ast2700a1-evb -m 8G -smp 4 -net nic,macaddr=,netdev=net0 -netdev user,id=net0,hostfwd=::2207-:22 -drive file=path/to/ast2700-default/image-bmc,format=raw,if=mtd -nographic -serial mon:stdio -snapshot >>>>> >>>>> Today, to attach an I2C device on one of the Aspeed SoC I2C buses : >>>>> >>>>> -device tmp105,bus=aspeed.i2c.bus.1,address=0x4d,id=tmp-test >>>>> >>>>> The Aspeed SoC I2C bus names follow the "aspeed.i2c.bus.X" format. >>>>> This is the model typename. The 2 new IO expander models attached >>>>> to the Aspeed SoC have an extra 16 I2C buses each. These buses use >>>>> an "ioexpX.Y" name, as proposed in the aspeed-next branch. >>>>> >>>>> Attaching a device to one of the IO expanders I2C buses would be : >>>>> >>>>> -device tmp105,bus=ioexp0.1,address=0x4d,id=tmp-test >>>>> >>>>> See the qtree below. >>>> >>>> Thank you! >>> >>> Thank you for taking the time of analyzing the code and history. >>> >>>> Machine ast2700a1-evb has QOM objects >>>> >>>> /machine/soc/i2c/ (aspeed.i2c-ast2700) >>>> /bus[N] (aspeed.i2c.bus) for N in 0..15 >>>> /aspeed.i2c.bus.N (i2c-bus) >>>> >>>> in both master and aspeed-11.0. >>> >>> Yes, that doesn't change because I would prefer not to break the current >>> user interface. The "i2c.X" bus name would have been a better choice. >>> I didn't anticipated that 10y ago when I proposed this model. >> >> We make mistakes, we learn :) >> >>>> Object aspeed.i2c-ast2700 is a sysbus device that contains 16 >>>> aspeed.i2c.bus objects as children bus[N] for N in 0..15. Each object >>>> has a property "bus-id" with value N. >>>> >>>> Object aspeed.i2c.bus is a sysbus device that contains an i2c-bus object >>>> as child aspeed.i2c.bus.N. >>>> >>>> Aside: why parent TYPE_SYS_BUS_DEVICE, and not TYPE_DEVICE? It doesn't >>>> actually plug into a sysbus... >>> >>> The AspeedI2CBus model has a couple of MRs and an IRQ. I guess that's why. >> >> Sysbus was a questionable idea from the start. >> >> Qdev was built around the design assumption "each device plugs into a >> bus provided by a device". This isn't not how real hardware works, but >> simplifications can be useful. However, this one broke down right away: >> most onboard devices and many other devices don't plug into a >> recognizable bus. To make the assumption work, Paul Brook invented the >> catch all "system bus". Various infrastructure was then tied to the >> system bus over time, because it needed to be tied to something, system >> bus is something, therefore it needed to be tied to the system bus. >> >> The design assumption is long gone. We still create system bus devices >> just to be able to use infrastructure. Blerch. >> >> End of digression. >> >>>> Object i2c-bus is a qbus. >>>> >>>> In master, object aspeed.i2c.bus computes the child name by appending .N >>>> to its own type name TYPE_ASPEED_I2C_BUS. >>>> >>>> In aspeed-11.0, it takes it from its property "bus-name". The property >>>> is set by its QOM parent aspeed.i2c-ast2700, and computed by appending >>>> .N to the value of its property "bus-label". It defaults the property >>>> to TYPE_ASPEED_I2C_BUS. >>>> >>>> Since nothing sets this property in this case, we get the same child >>>> name. >>>> >>>> aspeed-11.0 additionally has QOM objects >>>> >>>> /machine/soc/ioexp[M] (aspeed.ast1700) for M in 0..1 >>>> /ioexp-i2c[0] (aspeed.i2c-ast2700) >>>> /bus[N] (aspeed.i2c.bus) for N in 0..15 >>>> /ioexpM.N (i2c-bus) >>>> >>>> Object aspeed.ast1700 is a sysbus device that contains an >>>> aspeed.i2c-ast2700 as child "ioexp-i2c[0]". It has a property >>>> "board-idx" with value M. >>>> >>>> Aside: we only ever create one aspeed.i2c-ast2700 child. Why [0]? >>> >>> Right. We can drop [*] in aspeed_ast1700_instance_init() - PATCH 15. >>> >>>> Aside^2: I tried to strangle the "[*]" feature in the crib, but failed. >>>> Has been a minor thorn in my side ever since. >>>> >>>> aspeed.ast1700 set its child's (aspeed.i2c-ast2700) property "bus-label" >>>> to "ioexpM". This makes the child set the grandchild's (aspeed.i2c.bus) >>>> property "bus-name" to "ioexpM.N", which makes the grandchild name the >>>> great-grandchild (i2c-bus) "ioexpM.N". >>>> >>>> This naming business is complicated, and I had a hard time ferreting it >>>> out. As far as I can tell, it's all in service of -device bus=... >>> >>> yes. >>> >>> That's why I regret not letting QEMU taking care of the naming with : >>> >>> s->bus = i2c_init_bus(dev, NULL); >>> >>> This would break the user interface though. This is still an option. >> >> Since the devices providing these i2c buses have no qdev ID, these buses >> would then be named i2c.N, where N counts up from 0. I think. See "Bus >> names are defined as follows" below. >> >> Good enough? > > Good enough to avoid the bus naming conflict, not good enough > to easily identify a bus in the machine topology and it's also > breaking the user interface ... too many cons to be a good > choice. How is it breaking the user interface? Mind, I didn't mean to propose changing existing bus names, i.e. the bus names "aspeed.i2c.bus.N" of the i2c bus objects at /machine/soc/i2c/bus[N]/aspeed.i2c_init_bus.N. Only the bus names of the new i2c bus objects at /machine/soc/ioexp[M]/ioexp-i2c[0]/bus[N]/NEW-BUS-OBJECT. >>>> Let's examine how that works. >>>> >>>> We want to be able to plug i2c devices into any of these 48 i2c buses >>>> with -device / device_add. To do that, we need to select a bus with the >>>> "bus" argument. >>>> >>>> In a world saner than the one we live in, the value of "bus" would be a >>>> QOM path or qdev ID, where qdev ID is shorthand for the QOM path >>>> /machine/peripheral/ID. >> >> Nonsense. >> >> "QOM path or qdev ID" is how the @id argument of device_del and >> device_sync_config work. A qdev ID resolves to a qdev. Here, we need >> to resolve to a qbus. >> >> Instead, "QOM path or qbus ID". Except the concept "qbus ID" does not >> exist. All we have is qbus names, which aren't unique (we screwed that >> up). >> >>>> For instance, the first i2c bus could then be selected with absolute QOM >>>> path "/machine/soc/i2c/bus[0]" or partial QOM paths "soc/i2c/bus[0]" or >>>> "i2c/bus[0]". Partial QOM paths are a convenience feature that is >>>> virtually unknown (and possibly ill-advised): you can omit leading path >>>> components as long as there's no ambiguity. >>>> >>>> However, in the world we live in, the value of bus is not a QOM path, >>>> it's a path in the qtree. Why? qdev and -device / device_add predate >>>> QOM. >>>> >>>> If the path starts with "/", it's anchored at the main system bus. >>>> >>>> Else, it's anchored at a bus whose name is the first path component. If >>>> there's more than one such bus, we pick the first one we find. This is >>>> a misfeature. >>>> >>>> Remaining path components, if any, pick a path in the qtree from that >>>> anchor towards leaves. Note that the child of a qbus is always a qdev, >>>> and the child of a qdev always a qbus. >>>> >>>> This must ultimately resolve to a qbus of the appropriate type. >>>> >>>> Picking a qdev child of a qbus works like this: >>>> >>>> * If a child with a (user-specified) qdev ID equal to the path component >>>> exists, pick it. Since qdev IDs are unique, there can only be one. >>>> >>>> * Else, if children whose QOM type name equals the path component >>>> exists, pick the first one. >>>> >>>> * Else, if children whose qdev alias equals the path component exists, >>>> pick the first one. >>>> >>>> Picking the first one is again a misfeature. >>>> >>>> Picking a qbus child is simpler: we pick the first child whose bus name >>>> equals the path component. >>>> >>>> Bus names are defined as follows: >>>> >>>> * Whatever creates the bus may set its name. >>>> >>>> * Else, if the qbus's parent qdev has an ID, the bus name is ID.N, where >>>> N counts up from 0 within that qdev. >>>> >>>> * Else, the bus name is TYPE.N, where TYPE is the parent qdev's QOM type >>>> name, and N counts up from 0 within that bus class. >> >> The qbus's QOM type name, of course. >> >>>> The only case where this is actually works is picking the N-th bus child >>>> provided by a qdev with an ID: use bus=ID.N (a partial tree path of just >>>> one component). Anything else is unfit for purpose, except in special >>>> cases, e.g. when the machine can have just one device of a certain type. >>>> >>>> This mess is harmless for user-created devices: just specify the ID. >>>> It's awful for onboard devices, which cannot have an ID. >>>> >>>> This is a qdev design flaw. It's not specific to I2C or Aspeed, as >>>> Philippe suspected. >>>> >>>> To illustrate it further, let's have a look at the qtree of machine >>>> ast2700a1-evb. Output of "info qtree" in master: >>>> >>>> bus: main-system-bus >>>> type System >>>> [...] >>>> dev: aspeed.i2c.bus, id "" for N in 0..15 >>>> [...] >>>> bus: aspeed.i2c.bus.N >>>> type i2c-bus >>>> [...] >>>> In aspeed-11.0, we additionally have >>>> >>>> dev: aspeed.i2c.bus, id "" for M in 0..1, N in 0..15 >>>> [...] >>>> bus: ioexpM.N >>>> type i2c-bus >>>> [...] >>>> >>>> The i2c-buses all have unique names: aspeed.i2c-bus.N and ioexpM.N. We >>>> can point to any of them with a partial qtree path of just one >>>> component: bus=NAME where NAME is one of these unique names works, and >>>> there is no ambiguity. >>>> >>>> The buses have unique names only because device code takes pains to make >>>> them configurable by parent devices, and the parent devices cooperate to >>>> configure them so the resulting bus names are unique. >>>> >>>> This is a lot of complexity to work around this qdev design flaw for >>>> just one special instance. >>>> >>>> Can we instead remedy the design flaw once and for all? >>>> >>>> Here't the obvious stupid idea: give -device / device_add the means to >>>> pick a bus by QOM path. >>>> >>>> Thoughts? >>> >>> Could we support both methods ? I mean looking up the bus by the >>> qtree name and by the QOM path ? >> >> We can't just change "bus". Management applications and human users >> rely on it. >> >> Except we might be able to break aspects that aren't actually used in >> anger. Is anyone using '/' in qtree paths in anger? I sure hope nobody >> does, because that way is madness. But it's hard to be reasonably sure. > > Could we add a prefix to the bus name argument to signify a change of > namespace for the lookup ? like 'qom:' or 'machine:' ? Hmm. The value of "bus" is a path in the qtree. It either starts with '/' (main system bus) or a bus name. Recall that a bus name can be * set by whatever creates the bus * ID.N, where ID is the parent qdev's ID. * TYPE.N, where TYPE is the bus's QOM type name. TYPE.N start with "qom:" or "machine:", because QOM type names cannot create ':' since commit b447378e121 (qom/object: Limit type names to alphanumerical and some few special characters). ID.N shouldn't start with "qom:" or "machine:", because * Users cannot pick qdev IDs containing ':' since commit b560a9ab9be (qemu-option: Reject anti-social IDs). Except they can, because we regressed in 9.2 I'll post a patch. * Code should not pick such qdev IDs (but it totally could). Likewise, code setting bus names containing ':' would be unwise (but it totally could). I'm not sure we want to rely on this particular house of cards. As so often, the combination of ill-advised convenience features and equally ill-advised loose syntax bites us in the butt. > > Thanks ! > > C. > >> If we can break '/' in the value of "bus", we could overload "bus": make >> it a QOM path or a qbus ID, similar to how device_del's @id is a QOM >> path or a qdev ID. We'd have to define "qbus ID". >> >> Instead, we could perhaps add an argument "parent" to specify the QOM >> parent object, mutually exclusive with "bus". For devices that plug >> into a certain kind of bus, the parent object must be an instance of >> that bus. >> >>> Thanks, >>> >>> C. >> >> You're welcome!
>>>> That's why I regret not letting QEMU taking care of the naming with : >>>> >>>> s->bus = i2c_init_bus(dev, NULL); >>>> >>>> This would break the user interface though. This is still an option. >>> >>> Since the devices providing these i2c buses have no qdev ID, these buses >>> would then be named i2c.N, where N counts up from 0. I think. See "Bus >>> names are defined as follows" below. >>> >>> Good enough? >> >> Good enough to avoid the bus naming conflict, not good enough >> to easily identify a bus in the machine topology and it's also >> breaking the user interface ... too many cons to be a good >> choice. > > How is it breaking the user interface? Sorry I might have misunderstood your comment. > Mind, I didn't mean to propose changing existing bus names, i.e. the bus > names "aspeed.i2c.bus.N" of the i2c bus objects at > /machine/soc/i2c/bus[N]/aspeed.i2c_init_bus.N. Only the bus names of > the new i2c bus objects at > /machine/soc/ioexp[M]/ioexp-i2c[0]/bus[N]/NEW-BUS-OBJECT. Yeah that's fine. This is would be a good addition if possible. Thanks, C.
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