Userspace should be able to initiate device reboots using the various
PSCI SYSTEM_RESET and SYSTEM_RESET2 types defined by PSCI spec. This
patch series introduces psci-reboot-mode driver that will induce
command-based resets to psci driver for executing the device reset.

The PSCI system reset calls takes two arguments: reset_type and cookie.
It defines predefined reset types, such as warm and cold reset, and
vendor-specific reset types which are SoC vendor specific. To support
these requirements, the reboot-mode framework is enhanced in two key
ways:
1. Support upto three 32 bit magic values as arguments. This enables to
support for a 32 bit reset_type and a 64 bit cookie).
2. Predefined modes: Add support for predefined reboot modes in the
framework.

With these enhancements, the patch series enables:
 - Arch Warm reset and system reset cold as predefined reboot modes.
 - Vendor-specific resets, configurable via the SoC-specific device tree.

Together, these changes allow userspace to trigger all above PSCI resets
from userspace.

Note on introducing PSCI-MFD:
In v19/20, psci-reboot-mode was implemented as a faux-device. Review
discussion suggested this may not be the best model for firmware-backed
consumers, and that representing PSCI users as regular platform devices
would be better. One suggestion was to add a PSCI-MFD driver, allowing
multiple consumers tied to a single PSCI node "arm,psci-1.0" be probed
as MFD cells.

Following this, the series adds a PSCI-MFD driver and introduces
cpuidle-psci-domain and psci-reboot-mode as child cells. To meet the
psci-reboot-mode requirement, the MFD core is extended to support
fwnode.
Reference discussions on this:
https://lore.kernel.org/all/20260306-faux-dev-with-fwnode-v1-1-792a86a62530@oss.qualcomm.com/

---
The patch is tested on rb3Gen2, lemans-ride, lemans-evk, monaco-ride,
qcs615-ride.

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

Changes in v24:
mfd: psci-mfd: Add psci-reboot-mode child cell
 - Remove the explicit check for availability of the reboot-mode node. (by Bart)
 - Fail psci-mfd probe only on fatal errors(-ENOMEM) while adding the
   psci-reboot-mode cell.
mfd: core: Add firmware-node support for MFD cells
 - Allow MFD child registration even when a named child cell not present,
  to align with of_compatible-based registration. (by sashiko)
 - Move named_fwnode logic to a separate function.
power: reset: Add psci-reboot-mode driver
 - Remove dependency on OF. (by Pavan)
 - Update for new changes in predefined modes.
dt-bindings: arm: Document reboot-mode magic
 - Fix the example DT entry. (by Rob)
 - Use unevaluatedProperties as false for the reboot-mode child schema.
firmware: psci: Introduce command-based resets
 - Update in-code documentation. (by Pavan)
 - Update namespace-based exports. (by Pavan)
 - Use synchronized write/read (smp_store_release / smp_load_acquire)for
   the reset command to support lockless atomic reads. (by sashiko)
power: reset: reboot-mode: Add support for predefined reboot modes
 - Remove the predefined list in reboot-mode and add a pointer to
   reboot_mode_entry. (by Pavan)
 - The registering driver fills and manages reboot_mode_entry. (by Pavan)
   - reboot-mode list to append reboot_mode_entry.
power: reset: reboot-mode: Support up to 3 magic values per mode
 - Add separate write function pointers for single-magic writes (existing
   drivers) and multi-value writes. (by Pavan/Bart)
 - Update count to u32. (by Pavan)
power: reset: reboot-mode: Remove devres-based allocations
 - Drop from this series, Sent as separate split-fixes patch.
- Link to v23: https://patch.msgid.link/20260714-arm-psci-system_reset2-vendor-reboots-v23-0-e7453c548c21@oss.qualcomm.com

Changes in v23:
mfd: core: Add firmware-node support to MFD cells
 - Add named_fwnode-based firmware node support in MFD cells.(by Bart)
 - Update the release path. (by Bart)
 - Add checks for duplicate fwnodes.
 - Update documentation for usage and limitations.
mfd: psci-mfd: Add psci-reboot-mode child cell
 - Update for a named_fwnode-based reboot-mode child cell. (By Bart)
 - Split psci-reboot-mode and psci-cpuidle-domain into separate child
   cells.
power: reset: Add psci-reboot-mode driver
 - Add COMPILE_TEST in Kconfig. (by Bart)
 - Update to support up to three u32 arguments to accommodate a
   32-bit reset_type and a 64-bit cookie. (By Sashiko, Lorenzo)
dt-bindings: arm: Document reboot mode magic
 - Update to support up to three u32 arguments to accommodate a
   32-bit reset_type and a 64-bit cookie.
 - Dropped reviewed by from Bart and Rob due to considerable changes.
firmware: psci: Introduce command-based resets
 - Update to support a 64-bit cookie. (By Sashiko, Lorenzo)
 - Update the flow so unsupported reset commands and any failures during
   reset command execution fall back to the
   Linux reboot_mode path. (By Sashiko)
power: reset: reboot-mode: Add support for predefined reboot modes
 - Handle errors and free lists in devm_reboot_mode_register(). (by Sashiko)
 - Update to support up to three u32 arguments.
power: reset: reboot-mode: Support up to 3 magic values per mode
 - Patch for 64 bit magic renamed.
 - Update to support up to three u32 arguments to accommodate a 32-bit
   reset_type and a 64-bit cookie.
 - Dropped reviewed by from Bart and Sebastian due to considerable changes.
- Link to v22: https://lore.kernel.org/r/20260514-arm-psci-system_reset2-vendor-reboots-v22-0-28a5bde07483@oss.qualcomm.com

Changes in v22:
By Bart:
  power: reset: reboot-mode: Add support for predefined reboot modes
  - Add reboot-mode helper to add predefined modes.
  - Add centralized init for reboot-mode.
  - Dropping Reviewed-by from Bartosz as changes may need a review.
  power: reset: Add psci-reboot-mode driver
  - Use reboot-mode helpers to initialize reboot-mode driver and add
    predefined modes.
  mfd: core: Add firmware-node support to MFD cells
  - Use callback function to get fwnode from a MFD child cell.
  mfd: psci-mfd: Add psci-reboot-mode child cell
  - Use callback function to return fwnode for reboot-mode.
By Pankaj:
  mfd: psci-mfd: Add PSCI MFD driver for cpuidle-psci-domain cell
  - Make MFD_PSCI defaults to y as ARM_PSCI_CPUIDLE_DOMAIN defaults to
    y and depends on it.
- Link to v21: https://lore.kernel.org/r/20260427-arm-psci-system_reset2-vendor-reboots-v21-0-dcf937775e73@oss.qualcomm.com

Changes in v21:
By Krzysztof
 power: reset: reboot-mode: Remove devres based allocations
  - remove fixes tag.
By Lorenzo
  firmware: psci: Introduce command-based resets
  - psci_set_reset_cmd() only takes reset_type/cookie as input params.
    - updated this as a encoded u64 reset_command - from Pavan Kondeti.
  - Update commit text for reason for explicit panic_handling.
  - Clean split of reset flow in psci_sys_reset via handle_reboot_mode and handle_cmd_reset.
  - Add psci_has_system_reset2_support() helper and PSCI reset-type defines.
By Lorenzo/Bart
 power: reset: Add psci-reboot-mode driver
  By Bart
   - Drop faux-device based probe.
   - Convert driver to platform-driver model (probed via PSCI MFD).
  By Lorenzo:
   - Use PSCI-specific predefined reset mode naming/magic.
   - Register arch-warm predefined mode only when SYSTEM_RESET2 is supported.
   - psci_reboot_mode_write to directly pass reset_type and cokie.
   - Add MAINTAINERS entry for drivers/power/reset/psci-reboot-mode.c.
By Bart
 mfd: psci-mfd: Introduce psci mfd driver for cpuidle-psci-domain cell
  - Introduce psci-mfd driver.
 mfd: Add psci-reboot-mode cell via fwnode
 - Register psci-reboot-mode from psci-mfd with reboot-mode child node
   fwnode.
 - Update reset Kconfig dependency to tie PSCI reboot-mode to MFD PSCI path.
For alignment:
 - mfd: core: Add firmware-node support to MFD cells
   - Add firmware-node support to MFD cells.
By Pavan
 power: reset: reboot-mode: Add support for predefined reboot modes
  - Move redundant logic of adding modes to list to a common function.
By Arnd
 - Remove refrences for Linux reboot-modes from code and commit text.
By Konrad
 - Updated all dt changes to add reboot-mode for supported board files.
- Link to v20: https://lore.kernel.org/r/20260304-arm-psci-system_reset2-vendor-reboots-v20-0-cf7d346b8372@oss.qualcomm.com

Changes in v20:
By Bart:
 power: reset: Add psci-reboot-mode driver
 - Check for psci compatible in init arm,psci-1.0
 - Node pointer should not be assigned in device probe.
   To Align on above:
   - Remove probe call for faux device.
   - Set node using device_set_node after faux_device_create.
   - Register the reboot mode using explicit call to psci_reboot_mode_register_device.
 - Updated in-code documentation.
For Alignment to use of device_property_xx:
 power: reset: reboot-mode: Add support for 64 bit magic
  - Use device_property_count_u32 instead of device_property_read_u32.
  - Check count of properties before reading.
  - u64 magic changed to u32 magic[2].
  - nvmem-reboot rebased on recent changes.
  - Update documentation and commit text.
power: reset: reboot-mode: Remove devres based allocations
 By Dmitry/Bart:
  - pr_err to pr_debug in case of invalid reboot-mode prop.
 By Bart:
  - Use device_property_read_u32 instead of of_property_read_u32.
  - Avoid repeated code for free list. Now calling unregister from
    error path of regiister_reboot_mode.
 - Fix magic assignment.
- Link to v19: https://lore.kernel.org/r/20251228-arm-psci-system_reset2-vendor-reboots-v19-0-ebb956053098@oss.qualcomm.com

Changes in v19:
- Add missing To/Cc entries (include devicetree list) – Thanks to
  Krzysztof for pointing this out.
- Fix compilation error in reboot-mode.c for ARCH=powerpc by explicitly
  including <linux/slab.h>.
- Link to v18: https://lore.kernel.org/r/20251223-arm-psci-system_reset2-vendor-reboots-v18-0-32fa9e76efc3@oss.qualcomm.com

Changes in v18:
 power: reset: reboot-mode: Remove devres based allocations
 - Update commit text for alignment. – Bart
 - Read magic before assigning kzalloc(info) in reboot_mode_register. - Mukesh
 - Update error handling path. - Mukesh
By Bjorn
 - Expose sysfs for reboot-mode bisected to different series-
   Link: https://lore.kernel.org/all/20251222-next-15nov_expose_sysfs-v21-0-244614135fd8@oss.qualcomm.com/
By Bjorn/Lorenzo/Mukesh
  power: reset: reboot-mode: Add support for 64 bit magic
  - Use FIELD_GET/FIELD_PREP for u64 magic wherever required.
  - Update commit text and add documentation for structure of 64 bit magic.
By Lorenzo
 - Remove direct reboot-mode registration by psci driver.
 - Add support for predefined reboot modes in reboot-mode framework.
 - Add psci-reboot-mode driver and implement a psci-resets to accommodate
   all psci-resets including warm, cold and customizable vendor-resets.
By Bjorn
 - Update DT patches for qcm6490, lemans, monaco and tolos.
  - Update commit text to include more details – By Bjorn
For Alignment
 - dt-bindings: arm: Document reboot mode magic
   - Update reboot mode documentation to clarify that argument1 should provide
     full value of reset_type along with the 31st bit wherever required.
 - DT patches for qcm6490, lemans, monaco and tolos.
   - Provide full value of reset_type including 31st bit.(eg:0x80000001).
- Link to v17: https://lore.kernel.org/r/20251109-arm-psci-system_reset2-vendor-reboots-v17-0-46e085bca4cc@oss.qualcomm.com

Previous versions:
- Link to v16: https://lore.kernel.org/r/20251015-arm-psci-system_reset2-vendor-reboots-v16-0-b98aedaa23ee@oss.qualcomm.com
- Link to v15: https://lore.kernel.org/r/20250922-arm-psci-system_reset2-vendor-reboots-v15-0-7ce3a08878f1@oss.qualcomm.com
- Link to v14: https://lore.kernel.org/r/20250815-arm-psci-system_reset2-vendor-reboots-v14-0-37d29f59ac9a@oss.qualcomm.com
- Link to v13: https://lore.kernel.org/r/20250727-arm-psci-system_reset2-vendor-reboots-v13-0-6b8d23315898@oss.qualcomm.com
- Link to v12: https://lore.kernel.org/r/20250721-arm-psci-system_reset2-vendor-reboots-v12-0-87bac3ec422e@oss.qualcomm.com
- Link to v11: https://lore.kernel.org/r/20250717-arm-psci-system_reset2-vendor-reboots-v11-0-df3e2b2183c3@oss.qualcomm.com
- Link to v10: https://lore.kernel.org/all/569f154d-c714-1714-b898-83a42a38771c@oss.qualcomm.com/
- Link to v9: https://lore.kernel.org/all/20250303-arm-psci-system_reset2-vendor-reboots-v9-0-b2cf4a20feda@oss.qualcomm.com/
- Link to v8: https://lore.kernel.org/r/20241107-arm-psci-system_reset2-vendor-reboots-v8-0-e8715fa65cb5@quicinc.com
- Link to v7: https://lore.kernel.org/r/20241028-arm-psci-system_reset2-vendor-reboots-v7-0-a4c40b0ebc54@quicinc.com
- Link to v6: https://lore.kernel.org/r/20241018-arm-psci-system_reset2-vendor-reboots-v6-0-50cbe88b0a24@quicinc.com
- Link to v5: https://lore.kernel.org/r/20240617-arm-psci-system_reset2-vendor-reboots-v5-0-086950f650c8@quicinc.com
- Link to v4: https://lore.kernel.org/r/20240611-arm-psci-system_reset2-vendor-reboots-v4-0-98f55aa74ae8@quicinc.com
- Link to v3: https://lore.kernel.org/r/20240515-arm-psci-system_reset2-vendor-reboots-v3-0-16dd4f9c0ab4@quicinc.com
- Link to v2: https://lore.kernel.org/r/20240414-arm-psci-system_reset2-vendor-reboots-v2-0-da9a055a648f@quicinc.com
- Link to v1: https://lore.kernel.org/r/20231117-arm-psci-system_reset2-vendor-reboots-v1-0-03c4612153e2@quicinc.com
- Link to RFC: https://lore.kernel.org/r/20231030-arm-psci-system_reset2-vendor-reboots-v1-0-dcdd63352ad1@quicinc.com

To: Lorenzo Pieralisi <lpieralisi@kernel.org>
To: Arnd Bergmann <arnd@arndb.de>
To: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
To: Bjorn Andersson <andersson@kernel.org>
To: Sebastian Reichel <sre@kernel.org>
To: Rob Herring <robh@kernel.org>
To: Sudeep Holla <sudeep.holla@arm.com>
To: Souvik Chakravarty <Souvik.Chakravarty@arm.com>
To: Krzysztof Kozlowski <krzk+dt@kernel.org>
To: Andy Yan <andy.yan@rock-chips.com>
To: Matthias Brugger <matthias.bgg@gmail.com>
To: Mark Rutland <mark.rutland@arm.com>
To: Conor Dooley <conor+dt@kernel.org>
To: Konrad Dybcio <konradybcio@kernel.org>
To: John Stultz <john.stultz@linaro.org>
To: Moritz Fischer <moritz.fischer@ettus.com>
To: Rafael J. Wysocki <rafael@kernel.org>
To: Daniel Lezcano <daniel.lezcano@kernel.org>
To: Christian Loehle <christian.loehle@arm.com>
To: Ulf Hansson <ulf.hansson@linaro.org>
To: Lee Jones <lee@kernel.org>
To: Ulf Hansson <ulfh@kernel.org>
To: Pavan Kondeti <pavan.kondeti@oss.qualcomm.com>
Cc: Florian Fainelli <florian.fainelli@broadcom.com>
Cc: Krzysztof Kozlowski <krzk@kernel.org>
Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Cc: Mukesh Ojha <mukesh.ojha@oss.qualcomm.com>
Cc: Andre Draszik <andre.draszik@linaro.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com>
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-arm-msm@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: mfd@lists.linux.dev

---
Shivendra Pratap (12):
      power: reset: reboot-mode: Support up to 3 magic values per mode
      power: reset: reboot-mode: Add support for predefined reboot modes
      firmware: psci: Introduce command-based resets
      mfd: psci-mfd: Add PSCI MFD driver for cpuidle-psci-domain cell
      dt-bindings: arm: Document reboot mode magic
      power: reset: Add psci-reboot-mode driver
      mfd: core: Add firmware-node support to MFD cells
      mfd: psci-mfd: Add psci-reboot-mode child cell
      arm64: dts: qcom: Add psci reboot-modes for kodiak boards
      arm64: dts: qcom: Add psci reboot-modes for lemans boards
      arm64: dts: qcom: Add psci reboot-modes for monaco boards
      arm64: dts: qcom: Add psci reboot-modes for talos boards

 Documentation/devicetree/bindings/arm/psci.yaml  |  58 +++++++
 MAINTAINERS                                      |   2 +
 arch/arm64/boot/dts/qcom/kodiak.dtsi             |   2 +-
 arch/arm64/boot/dts/qcom/lemans-evk.dts          |   7 +
 arch/arm64/boot/dts/qcom/lemans-ride-common.dtsi |   7 +
 arch/arm64/boot/dts/qcom/lemans.dtsi             |   2 +-
 arch/arm64/boot/dts/qcom/monaco-evk.dts          |   7 +
 arch/arm64/boot/dts/qcom/monaco.dtsi             |   2 +-
 arch/arm64/boot/dts/qcom/qcm6490-idp.dts         |   7 +
 arch/arm64/boot/dts/qcom/qcs615-ride.dts         |   7 +
 arch/arm64/boot/dts/qcom/qcs6490-rb3gen2.dts     |   7 +
 arch/arm64/boot/dts/qcom/qcs8300-ride.dts        |   7 +
 arch/arm64/boot/dts/qcom/talos.dtsi              |   2 +-
 drivers/cpuidle/Kconfig.arm                      |   1 +
 drivers/cpuidle/cpuidle-psci-domain.c            |   9 +-
 drivers/firmware/psci/psci.c                     | 112 +++++++++++-
 drivers/mfd/Kconfig                              |  12 ++
 drivers/mfd/Makefile                             |   2 +
 drivers/mfd/mfd-core.c                           | 151 +++++++++++++---
 drivers/mfd/psci-mfd.c                           |  68 ++++++++
 drivers/power/reset/Kconfig                      |  10 ++
 drivers/power/reset/Makefile                     |   1 +
 drivers/power/reset/nvmem-reboot-mode.c          |   7 +-
 drivers/power/reset/psci-reboot-mode.c           |  82 +++++++++
 drivers/power/reset/qcom-pon.c                   |   7 +-
 drivers/power/reset/reboot-mode.c                | 208 +++++++++++++++++------
 drivers/power/reset/syscon-reboot-mode.c         |   7 +-
 include/linux/mfd/core.h                         |  10 ++
 include/linux/psci.h                             |  15 ++
 include/linux/reboot-mode.h                      |  27 +++
 30 files changed, 751 insertions(+), 95 deletions(-)
---
base-commit: 415606a7be939835db9b0d6b711887586646346d
change-id: 20250709-arm-psci-system_reset2-vendor-reboots-46c80044afcf

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

On Mon, 03 Aug 2026, Shivendra Pratap wrote:

> Userspace should be able to initiate device reboots using the various
> PSCI SYSTEM_RESET and SYSTEM_RESET2 types defined by PSCI spec. This
> patch series introduces psci-reboot-mode driver that will induce
> command-based resets to psci driver for executing the device reset.

The more I read through this submission, the more convinced I get that
it does not belong in MFD.  This is a potentially nice "architectural
workaround" if it a) didn't break some of MFD's fundamental "real
devices only" rules, of which cpuidle and reboot-mode certainly are not
and b) didn't require a massive expansion of what the MFD core is
designed to do.  I am more that a little uncomfortable with the 150
lines being added to MFD core support this workaround.

My best suggestion so far would be to base these changes inside
drivers/firmware/psci and use the aux bus to communicate with the
various components.

-- 
Lee Jones

On Thu, Sep 3, 2026 at 6:04 PM Lee Jones <lee@kernel.org> wrote:
>
> On Mon, 03 Aug 2026, Shivendra Pratap wrote:
>
> > Userspace should be able to initiate device reboots using the various
> > PSCI SYSTEM_RESET and SYSTEM_RESET2 types defined by PSCI spec. This
> > patch series introduces psci-reboot-mode driver that will induce
> > command-based resets to psci driver for executing the device reset.
>
> The more I read through this submission, the more convinced I get that
> it does not belong in MFD.  This is a potentially nice "architectural
> workaround" if it a) didn't break some of MFD's fundamental "real
> devices only" rules, of which cpuidle and reboot-mode certainly are not
> and b) didn't require a massive expansion of what the MFD core is
> designed to do.  I am more that a little uncomfortable with the 150
> lines being added to MFD core support this workaround.
>
> My best suggestion so far would be to base these changes inside
> drivers/firmware/psci and use the aux bus to communicate with the
> various components.

We had some off list discussions about this as well and it seems like
we are in agreement. What you are suggesting makes perfect sense to
me.

Kind regards
Uffe

On 9/4/2026 12:47 PM, Ulf Hansson wrote:
> On Thu, Sep 3, 2026 at 6:04 PM Lee Jones <lee@kernel.org> wrote:
>>
>> On Mon, 03 Aug 2026, Shivendra Pratap wrote:
>>
>>> Userspace should be able to initiate device reboots using the various
>>> PSCI SYSTEM_RESET and SYSTEM_RESET2 types defined by PSCI spec. This
>>> patch series introduces psci-reboot-mode driver that will induce
>>> command-based resets to psci driver for executing the device reset.
>>
>> The more I read through this submission, the more convinced I get that
>> it does not belong in MFD.  This is a potentially nice "architectural
>> workaround" if it a) didn't break some of MFD's fundamental "real
>> devices only" rules, of which cpuidle and reboot-mode certainly are not
>> and b) didn't require a massive expansion of what the MFD core is
>> designed to do.  I am more that a little uncomfortable with the 150
>> lines being added to MFD core support this workaround.
>>
>> My best suggestion so far would be to base these changes inside
>> drivers/firmware/psci and use the aux bus to communicate with the
>> various components.
> 
> We had some off list discussions about this as well and it seems like
> we are in agreement. What you are suggesting makes perfect sense to
> me.

Thanks for reviews. I will move this to Aux and re-post.

thanks,
Shivendra