[WATCHDOG] rc32434_wdt: fix watchdog driver

The existing driver code wasn't working. Neither the timeout was set
correctly, nor system reset was being triggered, as the driver seemed
to keep the WDT alive himself. There was also some unnecessary code.
Signed-off-by: NPhil Sutter <n0-1@freewrt.org>
Signed-off-by: NWim Van Sebroeck <wim@iguana.be>
Cc: stable <stable@kernel.org>

drivers/watchdog/rc32434_wdt.c

@@ -34,104 +34,89 @@
 #include <asm/time.h>
 #include <asm/mach-rc32434/integ.h>
 
-#define MAX_TIMEOUT			20
-#define RC32434_WDT_INTERVAL		(15 * HZ)
-
-#define VERSION "0.2"
+#define VERSION "0.3"
 
 static struct {
-	struct completion stop;
-	int running;
-	struct timer_list timer;
-	int queue;
-	int default_ticks;
 	unsigned long inuse;
 } rc32434_wdt_device;
 
 static struct integ __iomem *wdt_reg;
-static int ticks = 100 * HZ;
 
 static int expect_close;
-static int timeout;
+
+/* Board internal clock speed in Hz,
+ * the watchdog timer ticks at. */
+extern unsigned int idt_cpu_freq;
+
+/* translate wtcompare value to seconds and vice versa */
+#define WTCOMP2SEC(x)	(x / idt_cpu_freq)
+#define SEC2WTCOMP(x)	(x * idt_cpu_freq)
+
+/* Use a default timeout of 20s. This should be
+ * safe for CPU clock speeds up to 400MHz, as
+ * ((2 ^ 32) - 1) / (400MHz / 2) = 21s.  */
+#define WATCHDOG_TIMEOUT 20
+
+static int timeout = WATCHDOG_TIMEOUT;
 
 static int nowayout = WATCHDOG_NOWAYOUT;
 module_param(nowayout, int, 0);
 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 
+/* apply or and nand masks to data read from addr and write back */
+#define SET_BITS(addr, or, nand) \
+	writel((readl(&addr) | or) & ~nand, &addr)
 
 static void rc32434_wdt_start(void)
 {
-	u32 val;
-
-	if (!rc32434_wdt_device.inuse) {
-		writel(0, &wdt_reg->wtcount);
+	u32 or, nand;
 
-		val = RC32434_ERR_WRE;
-		writel(readl(&wdt_reg->errcs) | val, &wdt_reg->errcs);
+	/* zero the counter before enabling */
+	writel(0, &wdt_reg->wtcount);
 
-		val = RC32434_WTC_EN;
-		writel(readl(&wdt_reg->wtc) | val, &wdt_reg->wtc);
-	}
-	rc32434_wdt_device.running++;
-}
+	/* don't generate a non-maskable interrupt,
+	 * do a warm reset instead */
+	nand = 1 << RC32434_ERR_WNE;
+	or = 1 << RC32434_ERR_WRE;
 
-static void rc32434_wdt_stop(void)
-{
-	u32 val;
+	/* reset the ERRCS timeout bit in case it's set */
+	nand |= 1 << RC32434_ERR_WTO;
 
-	if (rc32434_wdt_device.running) {
+	SET_BITS(wdt_reg->errcs, or, nand);
 
-		val = ~RC32434_WTC_EN;
-		writel(readl(&wdt_reg->wtc) & val, &wdt_reg->wtc);
+	/* reset WTC timeout bit and enable WDT */
+	nand = 1 << RC32434_WTC_TO;
+	or = 1 << RC32434_WTC_EN;
 
-		val = ~RC32434_ERR_WRE;
-		writel(readl(&wdt_reg->errcs) & val, &wdt_reg->errcs);
+	SET_BITS(wdt_reg->wtc, or, nand);
+}
 
-		rc32434_wdt_device.running = 0;
-	}
+static void rc32434_wdt_stop(void)
+{
+	/* Disable WDT */
+	SET_BITS(wdt_reg->wtc, 0, 1 << RC32434_WTC_EN);
 }
 
-static void rc32434_wdt_set(int new_timeout)
+static int rc32434_wdt_set(int new_timeout)
 {
-	u32 cmp = new_timeout * HZ;
-	u32 state, val;
+	int max_to = WTCOMP2SEC((u32)-1);
 
+	if (new_timeout < 0 || new_timeout > max_to) {
+		printk(KERN_ERR KBUILD_MODNAME
+			": timeout value must be between 0 and %d",
+			max_to);
+		return -EINVAL;
+	}
 	timeout = new_timeout;
-	/*
-	 * store and disable WTC
-	 */
-	state = (u32)(readl(&wdt_reg->wtc) & RC32434_WTC_EN);
-	val = ~RC32434_WTC_EN;
-	writel(readl(&wdt_reg->wtc) & val, &wdt_reg->wtc);
-
-	writel(0, &wdt_reg->wtcount);
-	writel(cmp, &wdt_reg->wtcompare);
-
-	/*
-	 * restore WTC
-	 */
-
-	writel(readl(&wdt_reg->wtc) | state, &wdt_reg);
-}
+	writel(SEC2WTCOMP(timeout), &wdt_reg->wtcompare);
 
-static void rc32434_wdt_reset(void)
-{
-	ticks = rc32434_wdt_device.default_ticks;
+	return 0;
 }
 
-static void rc32434_wdt_update(unsigned long unused)
+static void rc32434_wdt_ping(void)
 {
-	if (rc32434_wdt_device.running)
-		ticks--;
-
 	writel(0, &wdt_reg->wtcount);
-
-	if (rc32434_wdt_device.queue && ticks)
-		mod_timer(&rc32434_wdt_device.timer,
-			jiffies + RC32434_WDT_INTERVAL);
-	else
-		complete(&rc32434_wdt_device.stop);
 }
 
 static int rc32434_wdt_open(struct inode *inode, struct file *file)
@@ -142,19 +127,23 @@ static int rc32434_wdt_open(struct inode *inode, struct file *file)
 	if (nowayout)
 		__module_get(THIS_MODULE);
 
+	rc32434_wdt_start();
+	rc32434_wdt_ping();
+
 	return nonseekable_open(inode, file);
 }
 
 static int rc32434_wdt_release(struct inode *inode, struct file *file)
 {
-	if (expect_close && nowayout == 0) {
+	if (expect_close == 42) {
 		rc32434_wdt_stop();
 		printk(KERN_INFO KBUILD_MODNAME ": disabling watchdog timer\n");
 		module_put(THIS_MODULE);
-	} else
+	} else {
 		printk(KERN_CRIT KBUILD_MODNAME
 			": device closed unexpectedly. WDT will not stop !\n");
-
+		rc32434_wdt_ping();
+	}
 	clear_bit(0, &rc32434_wdt_device.inuse);
 	return 0;
 }
@@ -174,10 +163,10 @@ static ssize_t rc32434_wdt_write(struct file *file, const char *data,
 				if (get_user(c, data + i))
 					return -EFAULT;
 				if (c == 'V')
-					expect_close = 1;
+					expect_close = 42;
 			}
 		}
-		rc32434_wdt_update(0);
+		rc32434_wdt_ping();
 		return len;
 	}
 	return 0;
@@ -197,11 +186,11 @@ static long rc32434_wdt_ioctl(struct file *file, unsigned int cmd,
 	};
 	switch (cmd) {
 	case WDIOC_KEEPALIVE:
-		rc32434_wdt_reset();
+		rc32434_wdt_ping();
 		break;
 	case WDIOC_GETSTATUS:
 	case WDIOC_GETBOOTSTATUS:
-		value = readl(&wdt_reg->wtcount);
+		value = 0;
 		if (copy_to_user(argp, &value, sizeof(int)))
 			return -EFAULT;
 		break;
@@ -218,6 +207,7 @@ static long rc32434_wdt_ioctl(struct file *file, unsigned int cmd,
 			break;
 		case WDIOS_DISABLECARD:
 			rc32434_wdt_stop();
+			break;
 		default:
 			return -EINVAL;
 		}
@@ -225,11 +215,9 @@ static long rc32434_wdt_ioctl(struct file *file, unsigned int cmd,
 	case WDIOC_SETTIMEOUT:
 		if (copy_from_user(&new_timeout, argp, sizeof(int)))
 			return -EFAULT;
-		if (new_timeout < 1)
+		if (rc32434_wdt_set(new_timeout))
 			return -EINVAL;
-		if (new_timeout > MAX_TIMEOUT)
-			return -EINVAL;
-		rc32434_wdt_set(new_timeout);
+		/* Fall through */
 	case WDIOC_GETTIMEOUT:
 		return copy_to_user(argp, &timeout, sizeof(int));
 	default:
@@ -262,7 +250,7 @@ static int rc32434_wdt_probe(struct platform_device *pdev)
 	int ret;
 	struct resource *r;
 
-	r = platform_get_resource_byname(pdev, IORESOURCE_MEM, "rb500_wdt_res");
+	r = platform_get_resource_byname(pdev, IORESOURCE_MEM, "rb532_wdt_res");
 	if (!r) {
 		printk(KERN_ERR KBUILD_MODNAME
 			"failed to retrieve resources\n");
@@ -277,24 +265,12 @@ static int rc32434_wdt_probe(struct platform_device *pdev)
 	}
 
 	ret = misc_register(&rc32434_wdt_miscdev);
-
 	if (ret < 0) {
 		printk(KERN_ERR KBUILD_MODNAME
 			"failed to register watchdog device\n");
 		goto unmap;
 	}
 
-	init_completion(&rc32434_wdt_device.stop);
-	rc32434_wdt_device.queue = 0;
-
-	clear_bit(0, &rc32434_wdt_device.inuse);
-
-	setup_timer(&rc32434_wdt_device.timer, rc32434_wdt_update, 0L);
-
-	rc32434_wdt_device.default_ticks = ticks;
-
-	rc32434_wdt_start();
-
 	printk(banner, timeout);
 
 	return 0;
@@ -306,14 +282,8 @@ static int rc32434_wdt_probe(struct platform_device *pdev)
 
 static int rc32434_wdt_remove(struct platform_device *pdev)
 {
-	if (rc32434_wdt_device.queue) {
-		rc32434_wdt_device.queue = 0;
-		wait_for_completion(&rc32434_wdt_device.stop);
-	}
 	misc_deregister(&rc32434_wdt_miscdev);
-
 	iounmap(wdt_reg);
-
 	return 0;
 }