This series adds support for Low Power Idle (LPI) on ACPI based
platforms. 

LPI is described in the ACPI spec [1]. RISC-V FFH spec required to
enable this is available at [2].

[1] - https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html#lpi-low-power-idle-states 
[2] - https://github.com/riscv-non-isa/riscv-acpi-ffh/releases/download/v/riscv-ffh.pdf

Changes since v2:
	1) Added "riscv_" prefix for functions made non static (Feedback from Drew)
	2) Added RB tags from Drew.
	
Changes since v1:
	1) Reordered the commits such that the patch which enables
	   ACPI_PROCESSOR is the last one in the series.
	2) Used GENMASK and other changes to address Drew's comments.
	3) Moved common functions required by both DT and ACPI based cpuidle
	   drivers from the DT driver to common arch/riscv/suspend.c.
	4) ACPI cpuidle driver is added under drivers/acpi/riscv
	5) Rebased to latest for-next branch of linux-riscv.


Sunil V L (3):
  cpuidle: RISC-V: Move few functions to arch/riscv
  ACPI: RISC-V: Add LPI driver
  ACPI: Enable ACPI_PROCESSOR for RISC-V

 arch/riscv/include/asm/suspend.h    |  3 ++
 arch/riscv/kernel/suspend.c         | 49 +++++++++++++++++
 drivers/acpi/Kconfig                |  2 +-
 drivers/acpi/riscv/Makefile         |  3 +-
 drivers/acpi/riscv/cpuidle.c        | 81 +++++++++++++++++++++++++++++
 drivers/cpuidle/cpuidle-riscv-sbi.c | 49 ++---------------
 6 files changed, 141 insertions(+), 46 deletions(-)
 create mode 100644 drivers/acpi/riscv/cpuidle.c

-- 
2.34.1

On Thu, Jan 18, 2024 at 11:59:27AM +0530, Sunil V L wrote:
> This series adds support for Low Power Idle (LPI) on ACPI based
> platforms. 
> 
> LPI is described in the ACPI spec [1]. RISC-V FFH spec required to
> enable this is available at [2].

I'm interested in trying out this series. Might you be able to provide
some guidance on how to setup a test environment?

Are there specific branches of qemu and edk2 that I should use?

thanks,
drew

Hi Drew,

On Thu, Mar 14, 2024 at 07:59:46PM -0700, Drew Fustini wrote:
> On Thu, Jan 18, 2024 at 11:59:27AM +0530, Sunil V L wrote:
> > This series adds support for Low Power Idle (LPI) on ACPI based
> > platforms. 
> > 
> > LPI is described in the ACPI spec [1]. RISC-V FFH spec required to
> > enable this is available at [2].
> 
> I'm interested in trying out this series. Might you be able to provide
> some guidance on how to setup a test environment?
> 
> Are there specific branches of qemu and edk2 that I should use?
> 
1) You need LPI objects in the platform. I have added dummy objects for
testing this for qemu virt machine. Please use below branch.

https://github.com/vlsunil/qemu/tree/lpi_exp

Since interrupt controllers are not merged yet in linux, we need to boot
without any IO devices and use only polling based console and ram disk.
Above qemu branch disables IO devices as well.

2) Enable below config options while building linux kernel.
RISCV_SBI_V01
HVC_RISCV_SBI

3) Use upstream EDK2 (RiscVVirt)

4) Boot:
qemu-system-riscv64 \
 -M virt,pflash0=pflash0,pflash1=pflash1 \
 -m 2G -smp 8 \
 -serial mon:stdio \
 -blockdev node-name=pflash0,driver=file,read-only=on,filename=RISCV_VIRT_CODE.fd \
 -blockdev node-name=pflash1,driver=file,filename=RISCV_VIRT_VARS.fd \
 -kernel arch/riscv/boot/Image \
 -initrd buildroot/output/images/rootfs.cpio \
 -append "root=/dev/ram ro console=hvc earlycon=sbi"

Feel free to ping me if you have any difficulties.

Thanks!
Sunil

Hi Rafel,

On Thu, Jan 18, 2024 at 11:59:27AM +0530, Sunil V L wrote:
> This series adds support for Low Power Idle (LPI) on ACPI based
> platforms. 
> 
> LPI is described in the ACPI spec [1]. RISC-V FFH spec required to
> enable this is available at [2].
> 
> [1] - https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html#lpi-low-power-idle-states 
> [2] - https://github.com/riscv-non-isa/riscv-acpi-ffh/releases/download/v/riscv-ffh.pdf
> 
Could you please take a look at this series also and provide ACK if
looks fine?

Thanks,
Sunil
> Changes since v2:
> 	1) Added "riscv_" prefix for functions made non static (Feedback from Drew)
> 	2) Added RB tags from Drew.
> 	
> Changes since v1:
> 	1) Reordered the commits such that the patch which enables
> 	   ACPI_PROCESSOR is the last one in the series.
> 	2) Used GENMASK and other changes to address Drew's comments.
> 	3) Moved common functions required by both DT and ACPI based cpuidle
> 	   drivers from the DT driver to common arch/riscv/suspend.c.
> 	4) ACPI cpuidle driver is added under drivers/acpi/riscv
> 	5) Rebased to latest for-next branch of linux-riscv.
> 
> 
> Sunil V L (3):
>   cpuidle: RISC-V: Move few functions to arch/riscv
>   ACPI: RISC-V: Add LPI driver
>   ACPI: Enable ACPI_PROCESSOR for RISC-V
> 
>  arch/riscv/include/asm/suspend.h    |  3 ++
>  arch/riscv/kernel/suspend.c         | 49 +++++++++++++++++
>  drivers/acpi/Kconfig                |  2 +-
>  drivers/acpi/riscv/Makefile         |  3 +-
>  drivers/acpi/riscv/cpuidle.c        | 81 +++++++++++++++++++++++++++++
>  drivers/cpuidle/cpuidle-riscv-sbi.c | 49 ++---------------
>  6 files changed, 141 insertions(+), 46 deletions(-)
>  create mode 100644 drivers/acpi/riscv/cpuidle.c
> 
> -- 
> 2.34.1
>

On Thu, Feb 15, 2024 at 5:37 AM Sunil V L <sunilvl@ventanamicro.com> wrote:
>
> Hi Rafel,
>
> On Thu, Jan 18, 2024 at 11:59:27AM +0530, Sunil V L wrote:
> > This series adds support for Low Power Idle (LPI) on ACPI based
> > platforms.
> >
> > LPI is described in the ACPI spec [1]. RISC-V FFH spec required to
> > enable this is available at [2].
> >
> > [1] - https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html#lpi-low-power-idle-states
> > [2] - https://github.com/riscv-non-isa/riscv-acpi-ffh/releases/download/v/riscv-ffh.pdf
> >
> Could you please take a look at this series also and provide ACK if
> looks fine?

I cannot really comment on RISC-V-specific changes.

As for the ACPI Kconfig change, please feel free to add

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

to that patch.