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Sender: Guenter Roeck <groeck7@gmail.com>
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Date:   Sun, 16 Jul 2023 22:15:54 -0700
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Subject: Re: [PATCH v4 1/3] dt-bindings: watchdog: ti,rti-wdt: Add support for
 WDIOF_CARDRESET
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To:     huaqian.li@siemens.com, wim@linux-watchdog.org, robh+dt@kernel.org,
        krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org
Cc:     huaqianlee@gmail.com, nm@ti.com, vigneshr@ti.com,
        kristo@kernel.org, linux-watchdog@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, jan.kiszka@siemens.com,
        baocheng.su@siemens.com,
        Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        Conor Dooley <conor@kernel.org>, Rob Herring <robh@kernel.org>
References: <20230717040723.1306374-1-huaqian.li@siemens.com>
 <20230717040723.1306374-2-huaqian.li@siemens.com>
From:   Guenter Roeck <linux@roeck-us.net>
In-Reply-To: <20230717040723.1306374-2-huaqian.li@siemens.com>
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On 7/16/23 21:07, huaqian.li@siemens.com wrote:
> From: Li Hua Qian <huaqian.li@siemens.com>
> 
> TI RTI (Real Time Interrupt) Watchdog doesn't support to record the
> watchdog cause. Add a reserved memory to know the last reboot was caused
> by the watchdog card. In the reserved memory, some specific info will be
> saved to indicate whether the watchdog reset was triggered in last
> boot.
> 
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> Reviewed-by: Conor Dooley <conor@kernel.org>
> Reviewed-by: Rob Herring <robh@kernel.org>
> Signed-off-by: Li Hua Qian <huaqian.li@siemens.com>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
>   .../bindings/watchdog/ti,rti-wdt.yaml         | 41 +++++++++++++++++++
>   1 file changed, 41 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/watchdog/ti,rti-wdt.yaml b/Documentation/devicetree/bindings/watchdog/ti,rti-wdt.yaml
> index fc553211e42d..4b66c4fcdf35 100644
> --- a/Documentation/devicetree/bindings/watchdog/ti,rti-wdt.yaml
> +++ b/Documentation/devicetree/bindings/watchdog/ti,rti-wdt.yaml
> @@ -34,6 +34,20 @@ properties:
>     power-domains:
>       maxItems: 1
>   
> +  memory-region:
> +    maxItems: 1
> +    description:
> +      Contains the watchdog reserved memory. It is optional.
> +      In the reserved memory, the specified values, which are
> +      PON_REASON_SOF_NUM(0xBBBBCCCC), PON_REASON_MAGIC_NUM(0xDDDDDDDD),
> +      and PON_REASON_EOF_NUM(0xCCCCBBBB), are pre-stored at the first
> +      3 * 4 bytes to tell that last boot was caused by watchdog reset.
> +      Once the PON reason is captured by driver(rti_wdt.c), the driver
> +      is supposed to wipe the whole memory region. Surely, if this
> +      property is set, at least 12 bytes reserved memory starting from
> +      specific memory address(0xa220000) should be set. More please
> +      refer to Example 2.
> +
>   required:
>     - compatible
>     - reg
> @@ -59,3 +73,30 @@ examples:
>           assigned-clocks = <&k3_clks 252 1>;
>           assigned-clock-parents = <&k3_clks 252 5>;
>       };
> +
> +  - |
> +    // Example 2 (Add reserved memory for watchdog reset cause):
> +    /*
> +     * RTI WDT in main domain on J721e SoC. Assigned clocks are used to
> +     * select the source clock for the watchdog, forcing it to tick with
> +     * a 32kHz clock in this case. Add a reserved memory to keep the
> +     * watchdog reset cause persistent, which was be written in 12 bytes
> +     * starting from 0xa2200000 by RTI Watchdog Firmware.
> +     *
> +     * Reserved memory should be defined as follows:
> +     * reserved-memory {
> +     *     wdt_reset_memory_region: wdt-memory@a2200000 {
> +     *         reg = <0x00 0xa2200000 0x00 0x1000>;
> +     *         no-map;
> +     *     };
> +     * }
> +     */
> +    watchdog@40610000 {
> +        compatible = "ti,j7-rti-wdt";
> +        reg = <0x40610000 0x100>;
> +        clocks = <&k3_clks 135 1>;
> +        power-domains = <&k3_pds 135 TI_SCI_PD_EXCLUSIVE>;
> +        assigned-clocks = <&k3_clks 135 0>;
> +        assigned-clock-parents = <&k3_clks 135 4>;
> +        memory-region = <&wdt_reset_memory_region>;
> +    };