[PATCH v1 0/1] riscv: Introduce system suspend support

[Andrew Jones]

OpenSBI v1.3 and later supports the SUSP SBI extension which has recently
been frozen with the freezing of SBI 2.0. This one patch series adds
system suspend support to Linux, which implements "suspend-to-RAM". To
use it, build the kernel with CONFIG_SUSPEND, boot on a platform which
supports system suspend, and then issue 'echo mem > /sys/power/state'.
It's also possible to test this Linux support on a platform without
system suspend by using OpenSBI's system suspend test support. To enable
test support add

      opensbi-domains {
          compatible = "opensbi,domain,config";
          system-suspend-test;
      };

to the chosen node of the device tree. With the test node present,
OpenSBI will wait 5 seconds on a suspend and then kick a resume.

Note: Resume may fail without the fix for probing misaligned access
speed[1]. It's best to apply that fix before attempting system suspend.

[1] https://lore.kernel.org/all/20230920193801.3035093-1-evan@rivosinc.com/

Changes for v1:
  - Rebase on v6.6-rc1 -- only minor Kconfig change needed

Changes for RFC-v2:
  - RISCV_SBI dependency [Conor]
  - Rename SBI_EXT_SUSP_SUSPEND to SBI_EXT_SUSP_SYSTEM_SUSPEND and
    SBI_SUSP_SLEEP_TYPE_SUSPEND to SBI_SUSP_SLEEP_TYPE_SUSPEND_TO_RAM [Ley Foon]

Andrew Jones (1):
  riscv: sbi: Introduce system suspend support

 arch/riscv/Kconfig           |  5 ++++-
 arch/riscv/include/asm/sbi.h |  9 ++++++++
 arch/riscv/kernel/suspend.c  | 43 ++++++++++++++++++++++++++++++++++++
 3 files changed, 56 insertions(+), 1 deletion(-)

-- 
2.41.0