[PATCH v10 0/3] Add support to read the watchdog bootstatus from IMEM

[Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com>]

In Qualcomm IPQ SoCs, if the system is rebooted due to the watchdog
timeout, there is no way to identify it. Current approach of checking
the EXPIRED_STATUS in WDT_STS is not working.

To achieve this, if the system is rebooted due to watchdog timeout, the
information is captured in the IMEM by the bootloader (along with other
reason codes as well).

This series attempts to address this by adding the support to read the
IMEM and populate the information via bootstatus sysfs file.

With the CONFIG_WATCHDOG_SYSFS enabled, user can extract the information
as below:

cat
/sys/devices/platform/soc@0/f410000.watchdog/watchdog/watchdog0/bootstatus
32

Upto V9, this series has changes targeted for both qcom and watchdog
tree. So V10 was sent with only watchdog changes and it is picked into
watchdog tree[1]. For the remaining DTS patches, sending it as V10 again
which needs to be picked via qcom tree.

Since the watchdog changes are not yet reflected in linux-next yet, upon
merging this before the linux-next gets refreshed, below DT binding
warning will be seen

arch/arm64/boot/dts/qcom/ipq5424-rdp466.dtb: watchdog@f410000:
Unevaluated properties are not allowed ('sram' was unexpected)
        from schema $id:
http://devicetree.org/schemas/watchdog/qcom-wdt.yaml#

[1]
https://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging.git/log/?h=watchdog-next

Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com>
---
Changes in v10:
- Dropped the watchdog patches which are applied to watchdog's tree
- Link to v9: https://lore.kernel.org/all/20260228-wdt_reset_reason-v9-0-f96d7a4825d3@oss.qualcomm.com

Changes in v9:
- Picked up the R-b tag for 1/5
- In 4/5, if fetching the boot status failed, just log the error instead
  of exiting the probe
- Link to v8: https://lore.kernel.org/r/20260226-wdt_reset_reason-v8-0-011c3a8cb6ff@oss.qualcomm.com

Changes in v8:
- Collected the tags
- Updated the commit msg with reasoning in 1/5
- Updated the comment in 4/5
- Link to v7: https://lore.kernel.org/r/20260225-wdt_reset_reason-v7-0-65d5b7e3e1eb@oss.qualcomm.com

Changes in v7:
- Collected the tags
- Added the reference link in 1/5
- Added the flag 'no-memory-wc' in 2/5
- Link to v6: https://lore.kernel.org/r/20260130-wdt_reset_reason-v6-0-417ab789cd97@oss.qualcomm.com

Changes in v6:
- Moved the IMEM compatible from qcom,imem to sram binding
- Updated the 'sram' property in watchdog binding to point to SRAM
  region and update the watchdog driver accordingly
- Dropped the Konrad's R-b tag in 2/5

Changes in v5:
- Rename property 'qcom,imem' to 'sram'
- Use dev_err_probe instead of dev_err
- Link to v4:
  https://lore.kernel.org/linux-arm-msm/20250519-wdt_reset_reason-v4-0-d59d21275c75@oss.qualcomm.com/

Changes in v4:
- Kept only the WDIOF_CARDRESET and dropped other codes (Guenter)
- Renamed qcom_wdt_get_restart_reason() to qcom_wdt_get_bootstatus()
- Dropped the device data and describe the required information in the
  DT (Konrad)
- Link to v3:
  https://lore.kernel.org/linux-arm-msm/20250502-wdt_reset_reason-v3-0-b2dc7ace38ca@oss.qualcomm.com/

Changes in v3:
- Picked up the relevant tags
- Dropped the fallback compatible handling
- Split the driver changes into 2. Introduce the device data in one and
  extend the same in another for the use case
- Link to v2:
  https://lore.kernel.org/linux-arm-msm/20250416-wdt_reset_reason-v2-0-c65bba312914@oss.qualcomm.com/

Changes in v2:
- Dropped the RFC tag
- Reworked the driver changes to use the syscon API
- Link to v1:
  https://lore.kernel.org/linux-arm-msm/20250408-wdt_reset_reason-v1-0-e6ec30c2c926@oss.qualcomm.com/

Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com>

---
Kathiravan Thirumoorthy (3):
      dt-bindings: sram: describe the IPQ5424 IMEM as mmio-sram
      arm64: dts: qcom: ipq5424: Add the IMEM node
      arm64: dts: qcom: ipq5424: add support to get watchdog bootstatus from IMEM

 Documentation/devicetree/bindings/sram/qcom,imem.yaml |  1 -
 Documentation/devicetree/bindings/sram/sram.yaml      |  1 +
 arch/arm64/boot/dts/qcom/ipq5424.dtsi                 | 16 ++++++++++++++++
 3 files changed, 17 insertions(+), 1 deletion(-)
---
base-commit: e98d21c170b01ddef366f023bbfcf6b31509fa83
change-id: 20250610-wdt_reset_reason-7a5afe702075

Best regards,
--  
Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com>