watchdog: mpc8xxx: use the core worker function

The watchdog core includes a worker function which pings the
watchdog until user app starts pinging it and which also
pings it if the HW require more frequent pings.
Use that function instead of the dedicated timer.
In the mean time, we can allow the user to change the timeout.

Then change the timeout module parameter to use seconds and
use the watchdog_init_timeout() core function.

On some HW (eg: the 8xx), SWCRR contains bits unrelated to the
watchdog which have to be preserved upon write.

This driver has nothing preventing the use of the magic close, so
enable it.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/mpc8xxx_wdt.c

@@ -22,7 +22,6 @@
 #include <linux/fs.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
-#include <linux/timer.h>
 #include <linux/of_address.h>
 #include <linux/of_platform.h>
 #include <linux/module.h>
@@ -31,10 +30,13 @@
 #include <linux/uaccess.h>
 #include <sysdev/fsl_soc.h>
 
+#define WATCHDOG_TIMEOUT 10
+
 struct mpc8xxx_wdt {
 	__be32 res0;
 	__be32 swcrr; /* System watchdog control register */
 #define SWCRR_SWTC 0xFFFF0000 /* Software Watchdog Time Count. */
+#define SWCRR_SWF  0x00000008 /* Software Watchdog Freeze (mpc8xx). */
 #define SWCRR_SWEN 0x00000004 /* Watchdog Enable bit. */
 #define SWCRR_SWRI 0x00000002 /* Software Watchdog Reset/Interrupt Select bit.*/
 #define SWCRR_SWPR 0x00000001 /* Software Watchdog Counter Prescale bit. */
@@ -52,14 +54,15 @@ struct mpc8xxx_wdt_type {
 struct mpc8xxx_wdt_ddata {
 	struct mpc8xxx_wdt __iomem *base;
 	struct watchdog_device wdd;
-	struct timer_list timer;
 	spinlock_t lock;
+	u16 swtc;
 };
 
-static u16 timeout = 0xffff;
+static u16 timeout;
 module_param(timeout, ushort, 0);
 MODULE_PARM_DESC(timeout,
-	"Watchdog timeout in ticks. (0<timeout<65536, default=65535)");
+	"Watchdog timeout in seconds. (1<timeout<65535, default="
+	__MODULE_STRING(WATCHDOG_TIMEOUT) ")");
 
 static bool reset = 1;
 module_param(reset, bool, 0);
@@ -80,31 +83,27 @@ static void mpc8xxx_wdt_keepalive(struct mpc8xxx_wdt_ddata *ddata)
 	spin_unlock(&ddata->lock);
 }
 
-static void mpc8xxx_wdt_timer_ping(struct timer_list *t)
-{
-	struct mpc8xxx_wdt_ddata *ddata = from_timer(ddata, t, timer);
-
-	mpc8xxx_wdt_keepalive(ddata);
-	/* We're pinging it twice faster than needed, just to be sure. */
-	mod_timer(&ddata->timer, jiffies + HZ * ddata->wdd.timeout / 2);
-}
-
 static int mpc8xxx_wdt_start(struct watchdog_device *w)
 {
 	struct mpc8xxx_wdt_ddata *ddata =
 		container_of(w, struct mpc8xxx_wdt_ddata, wdd);
-
-	u32 tmp = SWCRR_SWEN | SWCRR_SWPR;
+	u32 tmp = in_be32(&ddata->base->swcrr);
 
 	/* Good, fire up the show */
+	tmp &= ~(SWCRR_SWTC | SWCRR_SWF | SWCRR_SWEN | SWCRR_SWRI | SWCRR_SWPR);
+	tmp |= SWCRR_SWEN | SWCRR_SWPR | (ddata->swtc << 16);
+
 	if (reset)
 		tmp |= SWCRR_SWRI;
 
-	tmp |= timeout << 16;
-
 	out_be32(&ddata->base->swcrr, tmp);
 
-	del_timer_sync(&ddata->timer);
+	tmp = in_be32(&ddata->base->swcrr);
+	if (!(tmp & SWCRR_SWEN))
+		return -EOPNOTSUPP;
+
+	ddata->swtc = tmp >> 16;
+	set_bit(WDOG_HW_RUNNING, &ddata->wdd.status);
 
 	return 0;
 }
@@ -118,17 +117,8 @@ static int mpc8xxx_wdt_ping(struct watchdog_device *w)
 	return 0;
 }
 
-static int mpc8xxx_wdt_stop(struct watchdog_device *w)
-{
-	struct mpc8xxx_wdt_ddata *ddata =
-		container_of(w, struct mpc8xxx_wdt_ddata, wdd);
-
-	mod_timer(&ddata->timer, jiffies);
-	return 0;
-}
-
 static struct watchdog_info mpc8xxx_wdt_info = {
-	.options = WDIOF_KEEPALIVEPING,
+	.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT,
 	.firmware_version = 1,
 	.identity = "MPC8xxx",
 };
@@ -137,7 +127,6 @@ static struct watchdog_ops mpc8xxx_wdt_ops = {
 	.owner = THIS_MODULE,
 	.start = mpc8xxx_wdt_start,
 	.ping = mpc8xxx_wdt_ping,
-	.stop = mpc8xxx_wdt_stop,
 };
 
 static int mpc8xxx_wdt_probe(struct platform_device *ofdev)
@@ -148,7 +137,6 @@ static int mpc8xxx_wdt_probe(struct platform_device *ofdev)
 	struct mpc8xxx_wdt_ddata *ddata;
 	u32 freq = fsl_get_sys_freq();
 	bool enabled;
-	unsigned int timeout_sec;
 
 	wdt_type = of_device_get_match_data(&ofdev->dev);
 	if (!wdt_type)
@@ -173,26 +161,17 @@ static int mpc8xxx_wdt_probe(struct platform_device *ofdev)
 	}
 
 	spin_lock_init(&ddata->lock);
-	timer_setup(&ddata->timer, mpc8xxx_wdt_timer_ping, 0);
 
 	ddata->wdd.info = &mpc8xxx_wdt_info,
 	ddata->wdd.ops = &mpc8xxx_wdt_ops,
 
-	/* Calculate the timeout in seconds */
-	timeout_sec = (timeout * wdt_type->prescaler) / freq;
-
-	ddata->wdd.timeout = timeout_sec;
+	ddata->wdd.timeout = WATCHDOG_TIMEOUT;
+	watchdog_init_timeout(&ddata->wdd, timeout, &ofdev->dev);
 
 	watchdog_set_nowayout(&ddata->wdd, nowayout);
 
-	ret = watchdog_register_device(&ddata->wdd);
-	if (ret) {
-		pr_err("cannot register watchdog device (err=%d)\n", ret);
-		return ret;
-	}
-
-	pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d (%d seconds)\n",
-		reset ? "reset" : "interrupt", timeout, timeout_sec);
+	ddata->swtc = min(ddata->wdd.timeout * freq / wdt_type->prescaler,
+			  0xffffU);
 
 	/*
 	 * If the watchdog was previously enabled or we're running on
@@ -200,7 +179,22 @@ static int mpc8xxx_wdt_probe(struct platform_device *ofdev)
 	 * userspace handles it.
 	 */
 	if (enabled)
-		mod_timer(&ddata->timer, jiffies);
+		mpc8xxx_wdt_start(&ddata->wdd);
+
+	ddata->wdd.max_hw_heartbeat_ms = (ddata->swtc * wdt_type->prescaler) /
+					 (freq / 1000);
+	ddata->wdd.min_timeout = ddata->wdd.max_hw_heartbeat_ms / 1000;
+	if (ddata->wdd.timeout < ddata->wdd.min_timeout)
+		ddata->wdd.timeout = ddata->wdd.min_timeout;
+
+	ret = watchdog_register_device(&ddata->wdd);
+	if (ret) {
+		pr_err("cannot register watchdog device (err=%d)\n", ret);
+		return ret;
+	}
+
+	pr_info("WDT driver for MPC8xxx initialized. mode:%s timeout=%d sec\n",
+		reset ? "reset" : "interrupt", ddata->wdd.timeout);
 
 	platform_set_drvdata(ofdev, ddata);
 	return 0;
@@ -212,7 +206,6 @@ static int mpc8xxx_wdt_remove(struct platform_device *ofdev)
 
 	pr_crit("Watchdog removed, expect the %s soon!\n",
 		reset ? "reset" : "machine check exception");
-	del_timer_sync(&ddata->timer);
 	watchdog_unregister_device(&ddata->wdd);
 
 	return 0;