The PSCI SYSTEM_RESET2 call allows vendor firmware to define additional reset types which could be mapped to the reboot argument. Setting up reboot on Qualcomm devices can be inconsistent from chipset to chipset. Generally, there is a PMIC register that gets written to decide the reboot type. There is also sometimes a cookie that can be written to indicate that the bootloader should behave differently than a regular boot. These knobs evolve over product generations and require more drivers. Qualcomm firmwares are beginning to expose vendor SYSTEM_RESET2 types to simplify driver requirements from Linux. Add support in PSCI to statically wire reboot mode commands from userspace to a vendor reset and cookie value using the device tree. The DT bindings are similar to reboot mode framework except that 2 integers are accepted (the type and cookie). Also, reboot mode framework is intended to program, but not reboot, the host. PSCI SYSTEM_RESET2 does both. I've not added support for reading ACPI tables since I don't have any device which provides them + firmware that supports vendor SYSTEM_RESET2 types. Previous discussions around SYSTEM_RESET2: - https://lore.kernel.org/lkml/20230724223057.1208122-2-quic_eberman@xxxxxxxxxxx/T/ - https://lore.kernel.org/all/4a679542-b48d-7e11-f33a-63535a5c68cb@xxxxxxxxxxx/ This RFC approach differs from the one sent in July by: - Not using the reboot mode framework - Added support to control both reset type and cookie - Implicitly dropped "normal" reboot command, which is always just SYSTEM_RESET anyway. Signed-off-by: Elliot Berman <quic_eberman@xxxxxxxxxxx> --- Elliot Berman (2): dt-bindings: arm: Document reboot mode magic firmware: psci: Read and use vendor reset types Documentation/devicetree/bindings/arm/psci.yaml | 13 ++++ drivers/firmware/psci/psci.c | 87 ++++++++++++++++++++++++- 2 files changed, 99 insertions(+), 1 deletion(-) --- base-commit: 22e877699642285c47f5d7d83b2d59815c29ebe8 change-id: 20231016-arm-psci-system_reset2-vendor-reboots-cc3ad456c070 Best regards, -- Elliot Berman <quic_eberman@xxxxxxxxxxx>
