Re: [PATCH v3 3/3] watchdog:rit_wdt: Add support for WDIOF_CARDRESET

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On 7/13/23 02:51, 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>
---
  drivers/watchdog/rti_wdt.c | 51 ++++++++++++++++++++++++++++++++++++++
  1 file changed, 51 insertions(+)

diff --git a/drivers/watchdog/rti_wdt.c b/drivers/watchdog/rti_wdt.c
index ce8f18e93aa9..b9435b972cb9 100644
--- a/drivers/watchdog/rti_wdt.c
+++ b/drivers/watchdog/rti_wdt.c
@@ -18,6 +18,8 @@
  #include <linux/pm_runtime.h>
  #include <linux/types.h>
  #include <linux/watchdog.h>
+#include <linux/of_address.h>
+#include <linux/of.h>

This driver so far managed to keep include files in alphabetic order.
Please keep it that way.

  #define DEFAULT_HEARTBEAT 60
@@ -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 +296,45 @@ static int rti_wdt_probe(struct platform_device *pdev)
  		}
  	}
+ node = of_parse_phandle(pdev->dev.of_node, "memory-region", 0);
+	if (!node) {
+		dev_dbg(dev, "No memory-region specified.\n");

If you really want that debug message, please keep the action part
first. I personally think it is just noise; the devicetree can always
be looked up if needed.

+	} else {
+		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 = res.end - (res.start - 1);

Please use resource_size().

+		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) {
+			dev_dbg(dev, "Watchdog reset cause detected.\n");

Isn't that a bit pointless ? That is obvious when reading the boot status.

+			wdd->bootstatus |= WDIOF_CARDRESET;
+		}
+		memset(vaddr, 0, reserved_mem_size);
+		memunmap(vaddr);
+	}
+
  	watchdog_init_timeout(wdd, heartbeat, dev);
ret = watchdog_register_device(wdd);




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