From 816981102c4237b5a40746c6a2d0fa3389584ce0 Mon Sep 17 00:00:00 2001
From: Jaehyoung Choi <jkkkkk.choi@samsung.com>
Date: Thu, 14 Sep 2017 17:55:52 +0900
Subject: [PATCH] [COMMON] watchdog: Add watchdog reset confirm function.

Currently mainline code does not support functions
to check whether watchdog works in real time.

The reset_confirm function checks
whether the watchdog timer actually generates a reset.

Change-Id: I569ab2f910b63160753838801d3c0b03f5a1a46d
Signed-off-by: Jaehyoung Choi <jkkkkk.choi@samsung.com>
---
 drivers/watchdog/s3c2410_wdt.c  | 49 +++++++++++++++++++++++++++++++++
 drivers/watchdog/watchdog_dev.c | 18 ++++++++++++
 include/linux/watchdog.h        |  1 +
 3 files changed, 68 insertions(+)

diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
index 90b1c1d3c43d..f4caf1989b97 100644
--- a/drivers/watchdog/s3c2410_wdt.c
+++ b/drivers/watchdog/s3c2410_wdt.c
@@ -433,6 +433,53 @@ static int s3c2410wdt_restart(struct watchdog_device *wdd, unsigned long action,
 	return 0;
 }
 
+inline void s3c2410wdt_reset_confirm(struct watchdog_device *wdd)
+{
+	struct s3c2410_wdt *wdt = watchdog_get_drvdata(wdd);
+	unsigned int wtcon, wtdat, wtcnt, disable_reg, mask_reset_reg;
+	unsigned long total_time = 0;
+	int ret;
+
+	if (!wdt)
+		return;
+
+	wtcon = readl(wdt->reg_base + S3C2410_WTCON);
+
+	dev_info(wdt->dev, "Current Little_cluster watchdog %sable, wtcon = %x\n",
+			(wtcon & S3C2410_WTCON_ENABLE) ? "en" : "dis", wtcon);
+
+	ret = regmap_read(wdt->pmureg, wdt->drv_data->mask_reset_reg, &mask_reset_reg);
+	if (ret) {
+		dev_err(wdt->dev, "Couldn't get MASK_WDT_RESET register\n");
+		return;
+	}
+
+	ret = regmap_read(wdt->pmureg, wdt->drv_data->disable_reg, &disable_reg);
+	if (ret) {
+		dev_err(wdt->dev, "Couldn't get DISABLE_WDT register\n");
+		return;
+	}
+
+	/*  Fake watchdog bits in both registers must be cleared. */
+	dev_info(wdt->dev, "DISABLE_WDT reg:  %x, MASK_WDT_RESET reg: %x\n", disable_reg, mask_reset_reg);
+
+	/* If watchdog is disabled, do not print wtcnt value. */
+	if (!(wtcon & S3C2410_WTCON_ENABLE))
+		return;
+
+	do {
+		/* It continues to print the wtcnt and wddat values
+		 * until watchdog reset is taken.
+		 */
+		wtdat = readl(wdt->reg_base + S3C2410_WTDAT);
+		wtcnt = readl(wdt->reg_base + S3C2410_WTCNT);
+		dev_info(wdt->dev, "%lu milliseconds, wtdat = %u, wtcnt = %u",
+				total_time, wtdat, wtcnt);
+		total_time += 500;
+		mdelay(500);
+	} while (total_time < (wdd->timeout * 1000));
+}
+
 #define OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
 
 static const struct watchdog_info s3c2410_wdt_ident = {
@@ -448,6 +495,7 @@ static const struct watchdog_ops s3c2410wdt_ops = {
 	.ping = s3c2410wdt_keepalive,
 	.set_timeout = s3c2410wdt_set_heartbeat,
 	.restart = s3c2410wdt_restart,
+	.reset_confirm = s3c2410wdt_reset_confirm,
 };
 
 static const struct watchdog_device s3c2410_wdd = {
@@ -657,6 +705,7 @@ inline int s3c2410wdt_set_emergency_reset(unsigned int timeout_cnt, int index)
 
 	return 0;
 }
+
 #endif
 
 #ifdef CONFIG_PM_SLEEP
diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index b30fb637ae94..dd69fd69f99b 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -527,6 +527,23 @@ static ssize_t pretimeout_governor_store(struct device *dev,
 }
 static DEVICE_ATTR_RW(pretimeout_governor);
 
+static ssize_t reset_confirm_show(struct device *dev,
+				struct device_attribute *attr,
+				char *buf)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+	int ret = watchdog_start(wdd);
+
+	if (ret)
+		return ret;
+
+	if (wdd->ops->reset_confirm)
+		wdd->ops->reset_confirm(wdd);
+
+	return sprintf(buf, "watchdog reset failed..\n");
+}
+static DEVICE_ATTR_RO(reset_confirm);
+
 static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
 				int n)
 {
@@ -558,6 +575,7 @@ static struct attribute *wdt_attrs[] = {
 	&dev_attr_nowayout.attr,
 	&dev_attr_pretimeout_governor.attr,
 	&dev_attr_pretimeout_available_governors.attr,
+	&dev_attr_reset_confirm.attr,
 	NULL,
 };
 
diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
index 44985c4a1e86..6099de359a18 100644
--- a/include/linux/watchdog.h
+++ b/include/linux/watchdog.h
@@ -53,6 +53,7 @@ struct watchdog_ops {
 	unsigned int (*get_timeleft)(struct watchdog_device *);
 	int (*restart)(struct watchdog_device *, unsigned long, void *);
 	long (*ioctl)(struct watchdog_device *, unsigned int, unsigned long);
+	void (*reset_confirm)(struct watchdog_device *);
 };
 
 /** struct watchdog_device - The structure that defines a watchdog device
-- 
2.20.1