Document the "qcom,imem" property for the watchdog device on Qualcomm
IPQ platforms. Use this property to extract the restart reason from
IMEM, which is updated by XBL. Populate the watchdog's bootstatus sysFS
entry with this information, when the system reboots due to a watchdog
timeout.
Describe this property for the IPQ5424 watchdog device and extend support
to other targets subsequently.
Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com>
---
Changes in v4:
- New patch
---
.../devicetree/bindings/watchdog/qcom-wdt.yaml | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml b/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml
index 49e2b807db0bc9d3edfc93ec41ad0df0b74ed032..bbe9b68ff4c8b813744ffd86bb52303943366fa2 100644
--- a/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml
+++ b/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml
@@ -81,6 +81,16 @@ properties:
minItems: 1
maxItems: 5
+ qcom,imem:
+ $ref: /schemas/types.yaml#/definitions/phandle-array
+ description:
+ phandle to the IMEM syscon node that exposes the system restart reason
+ items:
+ - items:
+ - description: phandle of IMEM syscon
+ - description: offset of restart reason region
+ - description: value indicate that the watchdog timeout has occurred
+
required:
- compatible
- reg
@@ -117,6 +127,16 @@ allOf:
required:
- clock-frequency
+ - if:
+ properties:
+ compatible:
+ contains:
+ enum:
+ - qcom,apss-wdt-ipq5424
+ then:
+ required:
+ - qcom,imem
+
unevaluatedProperties: false
examples:
--
2.34.1On Mon, May 19, 2025 at 02:04:03PM GMT, Kathiravan Thirumoorthy wrote: > Document the "qcom,imem" property for the watchdog device on Qualcomm > IPQ platforms. Use this property to extract the restart reason from > IMEM, which is updated by XBL. Populate the watchdog's bootstatus sysFS > entry with this information, when the system reboots due to a watchdog > timeout. > > Describe this property for the IPQ5424 watchdog device and extend support > to other targets subsequently. > > Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com> > --- > Changes in v4: > - New patch > --- > .../devicetree/bindings/watchdog/qcom-wdt.yaml | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml b/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml > index 49e2b807db0bc9d3edfc93ec41ad0df0b74ed032..bbe9b68ff4c8b813744ffd86bb52303943366fa2 100644 > --- a/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml > +++ b/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml > @@ -81,6 +81,16 @@ properties: > minItems: 1 > maxItems: 5 > > + qcom,imem: Shoouldn't this be existing 'sram' property? If IMEM is something similar to OCMEM, then we already use sram for that. > + $ref: /schemas/types.yaml#/definitions/phandle-array > + description: > + phandle to the IMEM syscon node that exposes the system restart reason > + items: > + - items: > + - description: phandle of IMEM syscon > + - description: offset of restart reason region > + - description: value indicate that the watchdog timeout has occurred > + > required: > - compatible > - reg > @@ -117,6 +127,16 @@ allOf: > required: > - clock-frequency > > + - if: > + properties: > + compatible: > + contains: > + enum: > + - qcom,apss-wdt-ipq5424 > + then: > + required: > + - qcom,imem No, drop this. That's an ABI break. Best regards, Krzysztof
On 5/20/25 9:25 AM, Krzysztof Kozlowski wrote: > On Mon, May 19, 2025 at 02:04:03PM GMT, Kathiravan Thirumoorthy wrote: >> Document the "qcom,imem" property for the watchdog device on Qualcomm >> IPQ platforms. Use this property to extract the restart reason from >> IMEM, which is updated by XBL. Populate the watchdog's bootstatus sysFS >> entry with this information, when the system reboots due to a watchdog >> timeout. >> >> Describe this property for the IPQ5424 watchdog device and extend support >> to other targets subsequently. >> >> Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com> >> --- >> Changes in v4: >> - New patch >> --- >> .../devicetree/bindings/watchdog/qcom-wdt.yaml | 20 ++++++++++++++++++++ >> 1 file changed, 20 insertions(+) >> >> diff --git a/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml b/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml >> index 49e2b807db0bc9d3edfc93ec41ad0df0b74ed032..bbe9b68ff4c8b813744ffd86bb52303943366fa2 100644 >> --- a/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml >> +++ b/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml >> @@ -81,6 +81,16 @@ properties: >> minItems: 1 >> maxItems: 5 >> >> + qcom,imem: > > Shoouldn't this be existing 'sram' property? If IMEM is something > similar to OCMEM, then we already use sram for that. We specifically want a handle to a predefined byte in IMEM, something akin to qcom,4ln-config-sel in Documentation/devicetree/bindings/phy/qcom,sc8280xp-qmp-pcie-phy.yaml Konrad
On 20/05/2025 18:00, Konrad Dybcio wrote: > On 5/20/25 9:25 AM, Krzysztof Kozlowski wrote: >> On Mon, May 19, 2025 at 02:04:03PM GMT, Kathiravan Thirumoorthy wrote: >>> Document the "qcom,imem" property for the watchdog device on Qualcomm >>> IPQ platforms. Use this property to extract the restart reason from >>> IMEM, which is updated by XBL. Populate the watchdog's bootstatus sysFS >>> entry with this information, when the system reboots due to a watchdog >>> timeout. >>> >>> Describe this property for the IPQ5424 watchdog device and extend support >>> to other targets subsequently. >>> >>> Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com> >>> --- >>> Changes in v4: >>> - New patch >>> --- >>> .../devicetree/bindings/watchdog/qcom-wdt.yaml | 20 ++++++++++++++++++++ >>> 1 file changed, 20 insertions(+) >>> >>> diff --git a/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml b/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml >>> index 49e2b807db0bc9d3edfc93ec41ad0df0b74ed032..bbe9b68ff4c8b813744ffd86bb52303943366fa2 100644 >>> --- a/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml >>> +++ b/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml >>> @@ -81,6 +81,16 @@ properties: >>> minItems: 1 >>> maxItems: 5 >>> >>> + qcom,imem: >> >> Shoouldn't this be existing 'sram' property? If IMEM is something >> similar to OCMEM, then we already use sram for that. > > We specifically want a handle to a predefined byte in IMEM, something akin > to qcom,4ln-config-sel in > > Documentation/devicetree/bindings/phy/qcom,sc8280xp-qmp-pcie-phy.yaml Nothing stops that with sram. Above example is poor, because it mentions syscon. There is no hardware as syscon. Does not exist. What is IMEM here, what is this relationship? Best regards, Krzysztof
On 5/21/25 8:53 AM, Krzysztof Kozlowski wrote: > On 20/05/2025 18:00, Konrad Dybcio wrote: >> On 5/20/25 9:25 AM, Krzysztof Kozlowski wrote: >>> On Mon, May 19, 2025 at 02:04:03PM GMT, Kathiravan Thirumoorthy wrote: >>>> Document the "qcom,imem" property for the watchdog device on Qualcomm >>>> IPQ platforms. Use this property to extract the restart reason from >>>> IMEM, which is updated by XBL. Populate the watchdog's bootstatus sysFS >>>> entry with this information, when the system reboots due to a watchdog >>>> timeout. >>>> >>>> Describe this property for the IPQ5424 watchdog device and extend support >>>> to other targets subsequently. >>>> >>>> Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com> >>>> --- >>>> Changes in v4: >>>> - New patch >>>> --- >>>> .../devicetree/bindings/watchdog/qcom-wdt.yaml | 20 ++++++++++++++++++++ >>>> 1 file changed, 20 insertions(+) >>>> >>>> diff --git a/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml b/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml >>>> index 49e2b807db0bc9d3edfc93ec41ad0df0b74ed032..bbe9b68ff4c8b813744ffd86bb52303943366fa2 100644 >>>> --- a/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml >>>> +++ b/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml >>>> @@ -81,6 +81,16 @@ properties: >>>> minItems: 1 >>>> maxItems: 5 >>>> >>>> + qcom,imem: >>> >>> Shoouldn't this be existing 'sram' property? If IMEM is something >>> similar to OCMEM, then we already use sram for that. >> >> We specifically want a handle to a predefined byte in IMEM, something akin >> to qcom,4ln-config-sel in >> >> Documentation/devicetree/bindings/phy/qcom,sc8280xp-qmp-pcie-phy.yaml > > Nothing stops that with sram. Above example is poor, because it mentions > syscon. There is no hardware as syscon. Does not exist. What is IMEM > here, what is this relationship? IMEM is indeed a small block of on-die SRAM. In this context, another subsystem may write a magic value at a known offset that would correspond to the platform having been rebooted by the watchdog. Now why the wdt register is cleared in the first place, I have no clue. Konrad
On 5/22/2025 9:15 PM, Konrad Dybcio wrote: > On 5/21/25 8:53 AM, Krzysztof Kozlowski wrote: >> On 20/05/2025 18:00, Konrad Dybcio wrote: >>> On 5/20/25 9:25 AM, Krzysztof Kozlowski wrote: >>>> On Mon, May 19, 2025 at 02:04:03PM GMT, Kathiravan Thirumoorthy wrote: >>>>> Document the "qcom,imem" property for the watchdog device on Qualcomm >>>>> IPQ platforms. Use this property to extract the restart reason from >>>>> IMEM, which is updated by XBL. Populate the watchdog's bootstatus sysFS >>>>> entry with this information, when the system reboots due to a watchdog >>>>> timeout. >>>>> >>>>> Describe this property for the IPQ5424 watchdog device and extend support >>>>> to other targets subsequently. >>>>> >>>>> Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com> >>>>> --- >>>>> Changes in v4: >>>>> - New patch >>>>> --- >>>>> .../devicetree/bindings/watchdog/qcom-wdt.yaml | 20 ++++++++++++++++++++ >>>>> 1 file changed, 20 insertions(+) >>>>> >>>>> diff --git a/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml b/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml >>>>> index 49e2b807db0bc9d3edfc93ec41ad0df0b74ed032..bbe9b68ff4c8b813744ffd86bb52303943366fa2 100644 >>>>> --- a/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml >>>>> +++ b/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml >>>>> @@ -81,6 +81,16 @@ properties: >>>>> minItems: 1 >>>>> maxItems: 5 >>>>> >>>>> + qcom,imem: >>>> Shoouldn't this be existing 'sram' property? If IMEM is something >>>> similar to OCMEM, then we already use sram for that. >>> We specifically want a handle to a predefined byte in IMEM, something akin >>> to qcom,4ln-config-sel in >>> >>> Documentation/devicetree/bindings/phy/qcom,sc8280xp-qmp-pcie-phy.yaml >> Nothing stops that with sram. Above example is poor, because it mentions >> syscon. There is no hardware as syscon. Does not exist. What is IMEM >> here, what is this relationship? > IMEM is indeed a small block of on-die SRAM. In this context, another subsystem > may write a magic value at a known offset that would correspond to the platform > having been rebooted by the watchdog. Now why the wdt register is cleared in the > first place, I have no clue. Thanks, Konrad for chiming in and providing the background information. With respect to the WDT register, when the interrupt is triggered, I see the expire bit is set in the watchdog register. The bite interrupt is handled by TZ and TZ does the system reboot. After the system reboots, bit is cleared. I have cross checked with the design team and they confirmed that the behavior is expected one. Krzysztof, Based on the discussions from the previous versions, I have made the changes. Can you help to guide me on how to handle this? Should I just name the property as "sram" and point to the sub block in the IMEM region like how it is done at [1][2], which is more or like similar to what I have submitted in V1 of this series[3] Or is the current approach acceptable? Or some other way to handle this? [1] https://lore.kernel.org/linux-arm-msm/20250523-topic-ipa_imem-v1-1-b5d536291c7f@oss.qualcomm.com/T/#u [2] https://lore.kernel.org/linux-arm-msm/20250523-topic-ipa_imem-v1-2-b5d536291c7f@oss.qualcomm.com/T/#u [3] https://lore.kernel.org/linux-arm-msm/20250408-wdt_reset_reason-v1-0-e6ec30c2c926@oss.qualcomm.com/ > > Konrad
On 5/23/25 4:35 PM, Kathiravan Thirumoorthy wrote: > > On 5/22/2025 9:15 PM, Konrad Dybcio wrote: >> On 5/21/25 8:53 AM, Krzysztof Kozlowski wrote: >>> On 20/05/2025 18:00, Konrad Dybcio wrote: >>>> On 5/20/25 9:25 AM, Krzysztof Kozlowski wrote: >>>>> On Mon, May 19, 2025 at 02:04:03PM GMT, Kathiravan Thirumoorthy wrote: >>>>>> Document the "qcom,imem" property for the watchdog device on Qualcomm >>>>>> IPQ platforms. Use this property to extract the restart reason from >>>>>> IMEM, which is updated by XBL. Populate the watchdog's bootstatus sysFS >>>>>> entry with this information, when the system reboots due to a watchdog >>>>>> timeout. >>>>>> >>>>>> Describe this property for the IPQ5424 watchdog device and extend support >>>>>> to other targets subsequently. >>>>>> >>>>>> Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@oss.qualcomm.com> >>>>>> --- >>>>>> Changes in v4: >>>>>> - New patch >>>>>> --- >>>>>> .../devicetree/bindings/watchdog/qcom-wdt.yaml | 20 ++++++++++++++++++++ >>>>>> 1 file changed, 20 insertions(+) >>>>>> >>>>>> diff --git a/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml b/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml >>>>>> index 49e2b807db0bc9d3edfc93ec41ad0df0b74ed032..bbe9b68ff4c8b813744ffd86bb52303943366fa2 100644 >>>>>> --- a/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml >>>>>> +++ b/Documentation/devicetree/bindings/watchdog/qcom-wdt.yaml >>>>>> @@ -81,6 +81,16 @@ properties: >>>>>> minItems: 1 >>>>>> maxItems: 5 >>>>>> + qcom,imem: >>>>> Shoouldn't this be existing 'sram' property? If IMEM is something >>>>> similar to OCMEM, then we already use sram for that. >>>> We specifically want a handle to a predefined byte in IMEM, something akin >>>> to qcom,4ln-config-sel in >>>> >>>> Documentation/devicetree/bindings/phy/qcom,sc8280xp-qmp-pcie-phy.yaml >>> Nothing stops that with sram. Above example is poor, because it mentions >>> syscon. There is no hardware as syscon. Does not exist. What is IMEM >>> here, what is this relationship? >> IMEM is indeed a small block of on-die SRAM. In this context, another subsystem >> may write a magic value at a known offset that would correspond to the platform >> having been rebooted by the watchdog. Now why the wdt register is cleared in the >> first place, I have no clue. > > > Thanks, Konrad for chiming in and providing the background information. With respect to the WDT register, when the interrupt is triggered, I see the expire bit is set in the watchdog register. The bite interrupt is handled by TZ and TZ does the system reboot. After the system reboots, bit is cleared. I have cross checked with the design team and they confirmed that the behavior is expected one. > > Krzysztof, Based on the discussions from the previous versions, I have made the changes. Can you help to guide me on how to handle this? Should I just name the property as "sram" and point to the sub block in the IMEM region like how it is done at [1][2], which is more or like similar to what I have submitted in V1 of this series[3] Or is the current approach acceptable? Or some other way to handle this? > > [1] https://lore.kernel.org/linux-arm-msm/20250523-topic-ipa_imem-v1-1-b5d536291c7f@oss.qualcomm.com/T/#u > > [2] https://lore.kernel.org/linux-arm-msm/20250523-topic-ipa_imem-v1-2-b5d536291c7f@oss.qualcomm.com/T/#u > > [3] https://lore.kernel.org/linux-arm-msm/20250408-wdt_reset_reason-v1-0-e6ec30c2c926@oss.qualcomm.com/ Let's go with desired-value-in-dt here.. I don't trust the firmware to never change. `sram` is prooobably fine, let's hear from Krzysztof Konrad
On 28/05/2025 19:16, Konrad Dybcio wrote: >> Krzysztof, Based on the discussions from the previous versions, I have made the changes. Can you help to guide me on how to handle this? Should I just name the property as "sram" and point to the sub block in the IMEM region like how it is done at [1][2], which is more or like similar to what I have submitted in V1 of this series[3] Or is the current approach acceptable? Or some other way to handle this? >> >> [1] https://lore.kernel.org/linux-arm-msm/20250523-topic-ipa_imem-v1-1-b5d536291c7f@oss.qualcomm.com/T/#u >> >> [2] https://lore.kernel.org/linux-arm-msm/20250523-topic-ipa_imem-v1-2-b5d536291c7f@oss.qualcomm.com/T/#u >> >> [3] https://lore.kernel.org/linux-arm-msm/20250408-wdt_reset_reason-v1-0-e6ec30c2c926@oss.qualcomm.com/ > > Let's go with desired-value-in-dt here.. I don't trust the firmware > to never change. `sram` is prooobably fine, let's hear from Krzysztof > I propose to go with 'sram' property. Best regards, Krzysztof
On 6/1/2025 9:21 PM, Krzysztof Kozlowski wrote: > On 28/05/2025 19:16, Konrad Dybcio wrote: >>> Krzysztof, Based on the discussions from the previous versions, I have made the changes. Can you help to guide me on how to handle this? Should I just name the property as "sram" and point to the sub block in the IMEM region like how it is done at [1][2], which is more or like similar to what I have submitted in V1 of this series[3] Or is the current approach acceptable? Or some other way to handle this? >>> >>> [1] https://lore.kernel.org/linux-arm-msm/20250523-topic-ipa_imem-v1-1-b5d536291c7f@oss.qualcomm.com/T/#u >>> >>> [2] https://lore.kernel.org/linux-arm-msm/20250523-topic-ipa_imem-v1-2-b5d536291c7f@oss.qualcomm.com/T/#u >>> >>> [3] https://lore.kernel.org/linux-arm-msm/20250408-wdt_reset_reason-v1-0-e6ec30c2c926@oss.qualcomm.com/ >> Let's go with desired-value-in-dt here.. I don't trust the firmware >> to never change. `sram` is prooobably fine, let's hear from Krzysztof >> > I propose to go with 'sram' property. Thanks Konrad and Krzysztof for the inputs. Let rename the property qcom,imem to sram and submit the next version. Thanks, Kathiravan T. > > Best regards, > Krzysztof
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