Stm32 SoCs embed debug peripherals such as Coresight. These peripherals
can monitor the activity of the cores. Because of that, they can be
used only if some features in the debug configuration are enabled.
Else, errors or firewall exceptions can be observed. Similarly to
the ETZPC(on stm32mp1x platforms) or the RIFSC(on stm32mp2x platforms),
debug-related peripherals access can be assessed at bus level to
prevent these issues from happening.
The debug configuration can only be accessed by the secure world.
That means that a service must be implemented in the secure world for
the kernel to check the firewall configuration. On OpenSTLinux, it is
done through a Debug access PTA in OP-TEE [1].
To represent the debug peripherals present on a dedicated debug bus,
create a debug bus node in the device tree and the associated driver
that will interact with this PTA.
[1]: https://github.com/OP-TEE/optee_os/pull/7673
Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
---
Changes in v6:
- Fix use of platform_driver_register() in probe of the stm32 debug bus
(unusable since dc23806a7c47 ("driver core: enforce device_lock for driver_match_device()"))
- Added all review tags
- Link to v5: https://lore.kernel.org/r/20260123-debug_bus-v5-0-90b670844241@foss.st.com
Changes in v5:
- Take into account Rob's comments for the debug bus documentation
- Link to v4: https://lore.kernel.org/r/20260122-debug_bus-v4-0-28f0f2a25f2c@foss.st.com
Changes in v4:
- Remove reg property from the debug bus and use ranges.
- Link to v3: https://lore.kernel.org/r/20260121-debug_bus-v3-0-4d32451180d0@foss.st.com
Changes in v3:
- Collect Rob's review tags
- Add stm32_firewall_get_grant_all_access() API and use it in the HDP
driver.
- Link to v2: https://lore.kernel.org/r/20260114-debug_bus-v2-0-5475c7841569@foss.st.com
Changes in v2:
- Fix kernel robot error by documenting the access-controllers property
in the missing coresight peripheral binding files.
- List the access controller items for HDP
- Various minor fixes in the debug bus binding file.
- Remove clock documentation and its presence in the DT node and driver.
Bus clock will be handled by the child nodes' drivers.
- stm32 debug bus driver:
- Depopulate the bus when .remove() is called
- Remove trace when error on devm_kzalloc() as the trace
function does nothing in case of ENOMEM.
- Remove use of of_match_ptr()
- Use tee bus callbacks
- Link to v1: https://lore.kernel.org/r/20260109-debug_bus-v1-0-8f2142b5a738@foss.st.com
---
Gatien Chevallier (12):
dt-bindings: document access-controllers property for coresight peripherals
dt-bindings: pinctrl: document access-controllers property for stm32 HDP
dt-bindings: bus: document the stm32 debug bus
bus: stm32_firewall: allow check on different firewall controllers
bus: stm32_firewall: add stm32_firewall_get_grant_all_access() API
drivers: bus: add the stm32 debug bus driver
arm: dts: stm32: introduce the debug bus for stm32mp1x platforms
arm: dts: stm32: enable the debug bus on stm32mp1x boards
arm: dts: stm32: enable CoreSight on stm32mp15xx-dkx boards
arm: dts: stm32: enable CoreSight on the stm32mp157c-ev1 board
arm: dts: stm32: enable CoreSight on the stm32mp135f-dk board
pinctrl: stm32: add firewall checks before probing the HDP driver
.../devicetree/bindings/arm/arm,coresight-cti.yaml | 3 +
.../bindings/arm/arm,coresight-dynamic-funnel.yaml | 3 +
.../devicetree/bindings/arm/arm,coresight-etm.yaml | 3 +
.../devicetree/bindings/arm/arm,coresight-stm.yaml | 3 +
.../devicetree/bindings/arm/arm,coresight-tmc.yaml | 3 +
.../bindings/arm/arm,coresight-tpiu.yaml | 3 +
.../bindings/bus/st,stm32mp131-dbg-bus.yaml | 76 +++++++
.../devicetree/bindings/pinctrl/st,stm32-hdp.yaml | 6 +
MAINTAINERS | 1 +
arch/arm/boot/dts/st/stm32mp131.dtsi | 117 ++++++++++
arch/arm/boot/dts/st/stm32mp135f-dk.dts | 24 ++
arch/arm/boot/dts/st/stm32mp151.dtsi | 172 ++++++++++++++
arch/arm/boot/dts/st/stm32mp153.dtsi | 68 ++++++
arch/arm/boot/dts/st/stm32mp157c-ev1.dts | 40 ++++
arch/arm/boot/dts/st/stm32mp15xx-dkx.dtsi | 40 ++++
drivers/bus/Kconfig | 10 +
drivers/bus/Makefile | 1 +
drivers/bus/stm32_dbg_bus.c | 251 +++++++++++++++++++++
drivers/bus/stm32_firewall.c | 44 +++-
drivers/pinctrl/stm32/pinctrl-stm32-hdp.c | 14 ++
include/linux/bus/stm32_firewall_device.h | 26 +++
21 files changed, 907 insertions(+), 1 deletion(-)
---
base-commit: 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f
change-id: 20260108-debug_bus-392666c7a3aa
Best regards,
--
Gatien Chevallier <gatien.chevallier@foss.st.com>