[PATCH v12 0/8] Implement vendor resets for PSCI SYSTEM_RESET2

Shivendra Pratap
2025-07-21T18:29:10Z

The PSCI SYSTEM_RESET2 call allows vendor firmware to define
additional reset types which could be mapped to the reboot
argument.

User-space should be able to reboot a device into different
operational boot-states supported by underlying bootloader and
firmware. Generally, some HW registers need to be written, based
on which the bootloader and firmware decide the next boot state
of device, after the reset. For example, a requirement on
Qualcomm platforms may state that reboot with "bootloader"
command, should reboot the device into bootloader flashing mode
and reboot with “edl” command, should reboot the device into an
Emergency flashing mode. Setting up such reboots on Qualcomm
devices can be inconsistent across SoC platforms and may require
setting different HW registers, where some of these registers may
not be accessible to HLOS. These knobs evolve over product
generations and require more drivers. PSCI defines a
vendor-specific reset in SYSTEM_RESET2 spec, which enables the
firmware to take care of underlying setting for any such
supported vendor-specific reboot. Qualcomm firmwares are
beginning to support and expose PSCI SYSTEM_RESET2
vendor-specific reset types to simplify driver requirements from
Linux. With such support added in the firmware, we now need a
Linux interface which can make use of the firmware calls for PSCI
vendor-specific resets. This will align such reboot requirement
across platforms and vendors.

The current psci driver supports two types of resets –
SYSTEM_RESET2 Arch warm-reset and SYSTEM_RESET cold-reset. The
patchset introduces the PSCI SYSTEM_RESET2 vendor-specific reset
into the reset path of the psci driver and aligns it to work with
reboot system call - LINUX_REBOOT_CMD_RESTART2, when used along
with a supported string-based command in “*arg”.

The patchset uses reboot-mode based commands, to define the
supported vendor reset-types commands in psci device tree node
and registers these commands with the reboot-mode framework.

The PSCI vendor-specific reset takes two arguments, being,
reset_type and cookie as defined by the spec. To accommodate this
requirement, enhance the reboot-mode framework to support two
32-bit arguments by switching to 64-bit magic values.

Along this line, the patchset also extends the reboot-mode
framework to add a non-device-based registration function, which
will allow drivers to register using device tree node, while
keeping backward compatibility for existing users of reboot-mode.
This will enable psci driver to register for reboot-mode and
implement a write function, which will save the magic and then
use it in psci reset path to make a vendor-specific reset call
into the firmware. In addition, the patchset will expose a sysfs
entry interface within reboot-mode which can be used by userspace
to view the supported reboot-mode commands.

The list of vendor-specific reset commands remains open due to
divergent requirements across vendors, but this can be
streamlined and standardized through dedicated device tree
bindings.

Currently three drivers register with reboot-mode framework -
syscon-reboot-mode, nvmem-reboot-mode and qcom-pon. Consolidated
list of commands currently added across various vendor DTs:
mode-loader
mode-normal
mode-bootloader
mode-charge
mode-fastboot
mode-reboot-ab-update
mode-recovery
mode-rescue
mode-shutdown-thermal
mode-shutdown-thermal-battery

Detailed list of commands being used by syscon-reboot-mode:
arm64/boot/dts/exynos/exynosautov9.dtsi:
mode-bootloader = <EXYNOSAUTOV9_BOOT_BOOTLOADER>;
mode-fastboot = <EXYNOSAUTOV9_BOOT_FASTBOOT>;
mode-recovery = <EXYNOSAUTOV9_BOOT_RECOVERY>;

arm64/boot/dts/exynos/google/gs101.dtsi:
mode-bootloader = <0xfc>;
mode-charge = <0x0a>;
mode-fastboot = <0xfa>;
mode-reboot-ab-update = <0x52>;
mode-recovery = <0xff>;
mode-rescue = <0xf9>;
mode-shutdown-thermal = <0x51>;
mode-shutdown-thermal-battery = <0x51>;

arm64/boot/dts/hisilicon/hi3660-hikey960.dts:
mode-normal = <0x77665501>;
mode-bootloader = <0x77665500>;
mode-recovery = <0x77665502>;

arm64/boot/dts/hisilicon/hi6220-hikey.dts:
mode-normal = <0x77665501>;
mode-bootloader = <0x77665500>;
mode-recovery = <0x77665502>;

arm64/boot/dts/rockchip/px30.dtsi:
mode-bootloader = <BOOT_BL_DOWNLOAD>;
mode-fastboot = <BOOT_FASTBOOT>;
mode-loader = <BOOT_BL_DOWNLOAD>;
mode-normal = <BOOT_NORMAL>;
mode-recovery = <BOOT_RECOVERY>;

arm64/boot/dts/rockchip/rk3308.dtsi:
mode-bootloader = <BOOT_BL_DOWNLOAD>;
mode-loader = <BOOT_BL_DOWNLOAD>;
mode-normal = <BOOT_NORMAL>;
mode-recovery = <BOOT_RECOVERY>;
mode-fastboot = <BOOT_FASTBOOT>;

arm64/boot/dts/rockchip/rk3566-lckfb-tspi.dts:
mode-normal = <BOOT_NORMAL>;
mode-loader = <BOOT_BL_DOWNLOAD>;
mode-recovery = <BOOT_RECOVERY>;
mode-bootloader = <BOOT_FASTBOOT>;

Detailed list of commands being used by nvmem-reboot-mode:
arm64/boot/dts/qcom/pmXXXX.dtsi:(multiple qcom DTs)
mode-recovery = <0x01>;
mode-bootloader = <0x02>;

Previous discussions around SYSTEM_RESET2:
- https://lore.kernel.org/lkml/20230724223057.1208122-2-quic_eberman@quicinc.com/T/
- https://lore.kernel.org/all/4a679542-b48d-7e11-f33a-63535a5c68cb@quicinc.com/

Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
Signed-off-by: Shivendra Pratap <shivendra.pratap@oss.qualcomm.com>

Changes in v12:
- Added lock for list traversals in reboot-mode - by Dmitry.
- Added proper handling for BE and LE cases in reboot-mode - by Dmitry.
- Removed type casting for u64 to u32 conversions. Added limit checks
and used bitwise operations for same - by Andrew.
- Link to v11: https://lore.kernel.org/r/20250717-arm-psci-system_reset2-vendor-reboots-v11-0-df3e2b2183c3@oss.qualcomm.com

Changes in v11:
- Remove reference of cookie in reboot-mode – Arnd/Rob
- Introduce 64-bit magic in reboot-mode to accommodate two 32-bit
arguments – Arnd
- Change reset-type to reboot-mode in psci device tree binding – Arnd
- binding no more mandates two arguments as in v10.
- dt changes done to support this binding.
- Remove obvious comments in psci reset path – Konrad
- Merge sysfs and ABI doc into single patch.
- Fix compilation issue on X86 configs.
- Fix warnings for pr_fmt.
- Link to v10: https://lore.kernel.org/all/569f154d-c714-1714-b898-83a42a38771c@oss.qualcomm.com/

Changes in V10:
- Change in reset-type binding to make cookie as a mandatory
argument.
- Change reboot-mode binding to support additional argument
"cookie".
From Lorenzo:
- Use reboot-mode framework for implementing vendor-resets.
- Modify reboot-mode framework to support two arguments
(magic and cookie).
- Expose sysfs for supported reboot-modes commands.
- List out all existing reboot-mode commands and their users.
- Added this to cover letter.
From Dmitry:
- Modify reboot-mode to support non-device based registration.
- Modify reboot-mode to create a class and device to expose
sysfs interface.
- Link to v9: https://lore.kernel.org/all/20250303-arm-psci-system_reset2-vendor-reboots-v9-0-b2cf4a20feda@oss.qualcomm.com/

Changes in v9:
- Don't fallback to architecturally defined resets from Lorenzo.
- Link to v8: https://lore.kernel.org/r/20241107-arm-psci-system_reset2-vendor-reboots-v8-0-e8715fa65cb5@quicinc.com

Changes in v8:
- Code style nits from Stephen
- Add rb3gen2
- Link to v7: https://lore.kernel.org/r/20241028-arm-psci-system_reset2-vendor-reboots-v7-0-a4c40b0ebc54@quicinc.com

Changes in v7:
- Code style nits from Stephen
- Dropped unnecessary hunk from the sa8775p-ride patch
- Link to v6: https://lore.kernel.org/r/20241018-arm-psci-system_reset2-vendor-reboots-v6-0-50cbe88b0a24@quicinc.com

Changes in v6:
- Rebase to v6.11 and fix trivial conflicts in qcm6490-idp
- Add sa8775p-ride support (same as qcm6490-idp)
- Link to v5: https://lore.kernel.org/r/20240617-arm-psci-system_reset2-vendor-reboots-v5-0-086950f650c8@quicinc.com

Changes in v5:
- Drop the nested "items" in prep for future dtschema tools
- Link to v4: https://lore.kernel.org/r/20240611-arm-psci-system_reset2-vendor-reboots-v4-0-98f55aa74ae8@quicinc.com

Changes in v4:
- Change mode- properties from uint32-matrix to uint32-array
- Restructure the reset-types node so only the restriction is in the
if/then schemas and not the entire definition
- Link to v3: https://lore.kernel.org/r/20240515-arm-psci-system_reset2-vendor-reboots-v3-0-16dd4f9c0ab4@quicinc.com

Changes in v3:
- Limit outer number of items to 1 for mode-* properties
- Move the reboot-mode for psci under a subnode "reset-types"
- Fix the DT node in qcm6490-idp so it doesn't overwrite the one from
sc7820.dtsi
- Link to v2: https://lore.kernel.org/r/20240414-arm-psci-system_reset2-vendor-reboots-v2-0-da9a055a648f@quicinc.com

Changes in v2:
- Fixes to schema as suggested by Rob and Krzysztof
- Add qcm6490 idp as first Qualcomm device to support
- Link to v1: https://lore.kernel.org/r/20231117-arm-psci-system_reset2-vendor-reboots-v1-0-03c4612153e2@quicinc.com

Changes in v1:
- Reference reboot-mode bindings as suggeted by Rob.
- Link to RFC: https://lore.kernel.org/r/20231030-arm-psci-system_reset2-vendor-reboots-v1-0-dcdd63352ad1@quicinc.com

---
Elliot Berman (4):
dt-bindings: arm: Document reboot mode magic
arm64: dts: qcom: qcm6490-idp: Add PSCI SYSTEM_RESET2 types
arm64: dts: qcom: qcs6490-rb3gen2: Add PSCI SYSTEM_RESET2 types
arm64: dts: qcom: sa8775p-ride: Add PSCI SYSTEM_RESET2 types

Shivendra Pratap (4):
power: reset: reboot-mode: Add device tree node-based registration
power: reset: reboot-mode: Add support for 64 bit magic
firmware: psci: Implement vendor-specific resets as reboot-mode
power: reset: reboot-mode: Expose sysfs for registered reboot_modes

.../testing/sysfs-class-reboot-mode-reboot_modes | 38 ++++++
Documentation/devicetree/bindings/arm/psci.yaml | 43 ++++++
arch/arm64/boot/dts/qcom/qcm6490-idp.dts | 7 +
arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts | 7 +
arch/arm64/boot/dts/qcom/sa8775p-ride.dtsi | 7 +
arch/arm64/boot/dts/qcom/sa8775p.dtsi | 2 +-
arch/arm64/boot/dts/qcom/sc7280.dtsi | 2 +-
drivers/firmware/psci/Kconfig | 1 +
drivers/firmware/psci/psci.c | 57 +++++++-
drivers/power/reset/nvmem-reboot-mode.c | 13 +-
drivers/power/reset/qcom-pon.c | 11 +-
drivers/power/reset/reboot-mode.c | 148 +++++++++++++++++----
drivers/power/reset/syscon-reboot-mode.c | 11 +-
include/linux/reboot-mode.h | 10 +-
14 files changed, 317 insertions(+), 40 deletions(-)
---
base-commit: 97987520025658f30bb787a99ffbd9bbff9ffc9d
change-id: 20250709-arm-psci-system_reset2-vendor-reboots-46c80044afcf

Best regards,
--
Shivendra Pratap <shivendra.pratap@oss.qualcomm.com>