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

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

[Kathiravan Thirumoorthy]

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>

[PATCH v10 1/3] dt-bindings: sram: describe the IPQ5424 IMEM as mmio-sram

[Kathiravan Thirumoorthy]

IMEM shouldn’t be treated as a syscon or simple-mfd because it’s really
just on‑chip SRAM, not a block of control registers or a device with
multiple hardware functions.

Describing it as generic mmio‑sram keeps the model simple and closer to
what the hardware actually is.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com>
---
 Documentation/devicetree/bindings/sram/qcom,imem.yaml | 1 -
 Documentation/devicetree/bindings/sram/sram.yaml      | 1 +
 2 files changed, 1 insertion(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/sram/qcom,imem.yaml b/Documentation/devicetree/bindings/sram/qcom,imem.yaml
index c63026904061..576e627fbc11 100644
--- a/Documentation/devicetree/bindings/sram/qcom,imem.yaml
+++ b/Documentation/devicetree/bindings/sram/qcom,imem.yaml
@@ -18,7 +18,6 @@ properties:
     items:
       - enum:
           - qcom,apq8064-imem
-          - qcom,ipq5424-imem
           - qcom,msm8226-imem
           - qcom,msm8974-imem
           - qcom,msm8976-imem
diff --git a/Documentation/devicetree/bindings/sram/sram.yaml b/Documentation/devicetree/bindings/sram/sram.yaml
index eb695698a03e..2f594f60e1e6 100644
--- a/Documentation/devicetree/bindings/sram/sram.yaml
+++ b/Documentation/devicetree/bindings/sram/sram.yaml
@@ -36,6 +36,7 @@ properties:
         - nvidia,tegra234-sysram
         - qcom,eliza-imem
         - qcom,hawi-imem
+        - qcom,ipq5424-imem
         - qcom,kaanapali-imem
         - qcom,milos-imem
         - qcom,rpm-msg-ram

-- 
2.34.1

[PATCH v10 2/3] arm64: dts: qcom: ipq5424: Add the IMEM node

[Kathiravan Thirumoorthy]

Add the IMEM node to the device tree to extract debugging information
like system restart reason, which is populated via IMEM. Define the
IMEM region to enable this functionality.

As described, overall IMEM region is 112KB but only initial 4KB is
accessible by all masters in the SoC.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com>
---
 arch/arm64/boot/dts/qcom/ipq5424.dtsi | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/ipq5424.dtsi b/arch/arm64/boot/dts/qcom/ipq5424.dtsi
index 876bf6a8b8ff..9b8410e32629 100644
--- a/arch/arm64/boot/dts/qcom/ipq5424.dtsi
+++ b/arch/arm64/boot/dts/qcom/ipq5424.dtsi
@@ -730,6 +730,17 @@ ssphy_0: phy@7d000 {
 			status = "disabled";
 		};
 
+		sram@8600000 {
+			compatible = "qcom,ipq5424-imem", "mmio-sram";
+			reg = <0 0x08600000 0 0x1c000>;
+			ranges = <0 0 0x08600000 0x1c000>;
+
+			no-memory-wc;
+
+			#address-cells = <1>;
+			#size-cells = <1>;
+		};
+
 		usb3: usb3@8af8800 {
 			compatible = "qcom,ipq5424-dwc3", "qcom,dwc3";
 			reg = <0 0x08af8800 0 0x400>;

-- 
2.34.1

[PATCH v10 3/3] arm64: dts: qcom: ipq5424: add support to get watchdog bootstatus from IMEM

[Kathiravan Thirumoorthy]

Add the "sram" property to the watchdog device node to enable
retrieval of the system restart reason from IMEM, populated by XBL.
Parse this information in the watchdog driver and update the bootstatus
sysFS if the restart was triggered by a watchdog timeout.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com>
---
 arch/arm64/boot/dts/qcom/ipq5424.dtsi | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/ipq5424.dtsi b/arch/arm64/boot/dts/qcom/ipq5424.dtsi
index 9b8410e32629..33ff00990513 100644
--- a/arch/arm64/boot/dts/qcom/ipq5424.dtsi
+++ b/arch/arm64/boot/dts/qcom/ipq5424.dtsi
@@ -624,6 +624,7 @@ watchdog@f410000 {
 			reg = <0 0x0f410000 0 0x1000>;
 			interrupts = <GIC_SPI 0 IRQ_TYPE_EDGE_RISING>;
 			clocks = <&sleep_clk>;
+			sram = <&restart_reason>;
 		};
 
 		qusb_phy_1: phy@71000 {
@@ -739,6 +740,10 @@ sram@8600000 {
 
 			#address-cells = <1>;
 			#size-cells = <1>;
+
+			restart_reason: restartreason-sram@7b0 {
+				reg = <0x7b0 0x4>;
+			};
 		};
 
 		usb3: usb3@8af8800 {

-- 
2.34.1