Re: [PATCH v6 3/3] watchdog:rit_wdt: Add support for WDIOF_CARDRESET

[Guenter Roeck]

On 7/17/23 19:10, huaqian.li@xxxxxxxxxxx wrote:
> From: Li Hua Qian <huaqian.li@xxxxxxxxxxx>
>
> This patch adds the WDIOF_CARDRESET support for the platform watchdog
> whose hardware does not support this feature, to know if the board
> reboot is due to a watchdog reset.
>
> This is done via reserved memory(RAM), which indicates if specific
> info saved, triggering the watchdog reset in last boot.
>
> Signed-off-by: Li Hua Qian <huaqian.li@xxxxxxxxxxx>

Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>

> ---
>   drivers/watchdog/rti_wdt.c | 48 ++++++++++++++++++++++++++++++++++++++
>   1 file changed, 48 insertions(+)
>
> diff --git a/drivers/watchdog/rti_wdt.c b/drivers/watchdog/rti_wdt.c
> index ce8f18e93aa9..901109d979f0 100644
> --- a/drivers/watchdog/rti_wdt.c
> +++ b/drivers/watchdog/rti_wdt.c
> @@ -14,6 +14,8 @@
>   #include <linux/mod_devicetable.h>
>   #include <linux/module.h>
>   #include <linux/moduleparam.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
>   #include <linux/platform_device.h>
>   #include <linux/pm_runtime.h>
>   #include <linux/types.h>
> @@ -52,6 +54,11 @@
>   
>   #define DWDST			BIT(1)
>   
> +#define PON_REASON_SOF_NUM	0xBBBBCCCC
> +#define PON_REASON_MAGIC_NUM	0xDDDDDDDD
> +#define PON_REASON_EOF_NUM	0xCCCCBBBB
> +#define RESERVED_MEM_MIN_SIZE	12
> +
>   static int heartbeat = DEFAULT_HEARTBEAT;
>   
>   /*
> @@ -198,6 +205,11 @@ static int rti_wdt_probe(struct platform_device *pdev)
>   	struct rti_wdt_device *wdt;
>   	struct clk *clk;
>   	u32 last_ping = 0;
> +	struct device_node *node;
> +	u32 reserved_mem_size;
> +	struct resource res;
> +	u32 *vaddr;
> +	u64 paddr;
>   
>   	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
>   	if (!wdt)
> @@ -284,6 +296,42 @@ static int rti_wdt_probe(struct platform_device *pdev)
>   		}
>   	}
>   
> +	node = of_parse_phandle(pdev->dev.of_node, "memory-region", 0);
> +	if (node) {
> +		ret = of_address_to_resource(node, 0, &res);
> +		if (ret) {
> +			dev_err(dev, "No memory address assigned to the region.\n");
> +			goto err_iomap;
> +		}
> +
> +		/*
> +		 * If reserved memory is defined for watchdog reset cause.
> +		 * Readout the Power-on(PON) reason and pass to bootstatus.
> +		 */
> +		paddr = res.start;
> +		reserved_mem_size = resource_size(&res);
> +		if (reserved_mem_size < RESERVED_MEM_MIN_SIZE) {
> +			dev_err(dev, "The size of reserved memory is too small.\n");
> +			ret = -EINVAL;
> +			goto err_iomap;
> +		}
> +
> +		vaddr = memremap(paddr, reserved_mem_size, MEMREMAP_WB);
> +		if (vaddr == NULL) {
> +			dev_err(dev, "Failed to map memory-region.\n");
> +			ret = -ENOMEM;
> +			goto err_iomap;
> +		}
> +
> +		if (vaddr[0] == PON_REASON_SOF_NUM &&
> +		    vaddr[1] == PON_REASON_MAGIC_NUM &&
> +		    vaddr[2] == PON_REASON_EOF_NUM) {
> +			wdd->bootstatus |= WDIOF_CARDRESET;
> +		}
> +		memset(vaddr, 0, reserved_mem_size);
> +		memunmap(vaddr);
> +	}
> +
>   	watchdog_init_timeout(wdd, heartbeat, dev);
>   
>   	ret = watchdog_register_device(wdd);