watchdog: davinci: change driver to use WDT core

To reduce code duplicate and increase code readability use WDT core
code to handle WDT interface.

Remove io_lock as the WDT core uses mutex to lock each wdt device.
Remove wdt_state as the WDT core tracks state with its own variable.

The watchdog_init_timeout() can read timeout value from timeout-sec
property if the passed value is out of bounds. The heartbeat is
initialized in next way. If heartbeat is not set thought module
parameter, try to read it's value from WDT node timeout-sec property.
If node has no one, use default value.

The heartbeat is hold in wdd->timeout by WDT core, so use it in
order to set timeout period.

Davinci WDT can't be stopped and once it's expired - it can be
rearmed only after hardware reset, that's why nowayout feature
is enforced.

Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

drivers/watchdog/Kconfig

@@ -271,6 +271,7 @@ config IOP_WATCHDOG
 config DAVINCI_WATCHDOG
 	tristate "DaVinci watchdog"
 	depends on ARCH_DAVINCI
+	select WATCHDOG_CORE
 	help
 	  Say Y here if to include support for the watchdog timer
 	  in the DaVinci DM644x/DM646x processors.

drivers/watchdog/davinci_wdt.c

@@ -3,7 +3,7 @@
  *
  * Watchdog driver for DaVinci DM644x/DM646x processors
  *
- * Copyright (C) 2006 Texas Instruments.
+ * Copyright (C) 2006-2013 Texas Instruments.
  *
  * 2007 (c) MontaVista Software, Inc. This file is licensed under
  * the terms of the GNU General Public License version 2. This program
@@ -15,18 +15,12 @@
 #include <linux/moduleparam.h>
 #include <linux/types.h>
 #include <linux/kernel.h>
-#include <linux/fs.h>
-#include <linux/miscdevice.h>
 #include <linux/watchdog.h>
 #include <linux/init.h>
-#include <linux/bitops.h>
 #include <linux/platform_device.h>
-#include <linux/spinlock.h>
-#include <linux/uaccess.h>
 #include <linux/io.h>
 #include <linux/device.h>
 #include <linux/clk.h>
-#include <linux/slab.h>
 #include <linux/err.h>
 
 #define MODULE_NAME "DAVINCI-WDT: "
@@ -61,31 +55,12 @@
 #define WDKEY_SEQ0		(0xa5c6 << 16)
 #define WDKEY_SEQ1		(0xda7e << 16)
 
-static int heartbeat = DEFAULT_HEARTBEAT;
-
-static DEFINE_SPINLOCK(io_lock);
-static unsigned long wdt_status;
-#define WDT_IN_USE        0
-#define WDT_OK_TO_CLOSE   1
-#define WDT_REGION_INITED 2
-#define WDT_DEVICE_INITED 3
-
+static int heartbeat;
 static void __iomem	*wdt_base;
 struct clk		*wdt_clk;
+static struct watchdog_device	wdt_wdd;
 
-static void wdt_service(void)
-{
-	spin_lock(&io_lock);
-
-	/* put watchdog in service state */
-	iowrite32(WDKEY_SEQ0, wdt_base + WDTCR);
-	/* put watchdog in active state */
-	iowrite32(WDKEY_SEQ1, wdt_base + WDTCR);
-
-	spin_unlock(&io_lock);
-}
-
-static void wdt_enable(void)
+static int davinci_wdt_start(struct watchdog_device *wdd)
 {
 	u32 tgcr;
 	u32 timer_margin;
@@ -93,8 +68,6 @@ static void wdt_enable(void)
 
 	wdt_freq = clk_get_rate(wdt_clk);
 
-	spin_lock(&io_lock);
-
 	/* disable, internal clock source */
 	iowrite32(0, wdt_base + TCR);
 	/* reset timer, set mode to 64-bit watchdog, and unreset */
@@ -105,9 +78,9 @@ static void wdt_enable(void)
 	iowrite32(0, wdt_base + TIM12);
 	iowrite32(0, wdt_base + TIM34);
 	/* set timeout period */
-	timer_margin = (((u64)heartbeat * wdt_freq) & 0xffffffff);
+	timer_margin = (((u64)wdd->timeout * wdt_freq) & 0xffffffff);
 	iowrite32(timer_margin, wdt_base + PRD12);
-	timer_margin = (((u64)heartbeat * wdt_freq) >> 32);
+	timer_margin = (((u64)wdd->timeout * wdt_freq) >> 32);
 	iowrite32(timer_margin, wdt_base + PRD34);
 	/* enable run continuously */
 	iowrite32(ENAMODE12_PERIODIC, wdt_base + TCR);
@@ -119,84 +92,28 @@ static void wdt_enable(void)
 	iowrite32(WDKEY_SEQ0 | WDEN, wdt_base + WDTCR);
 	/* put watchdog in active state */
 	iowrite32(WDKEY_SEQ1 | WDEN, wdt_base + WDTCR);
-
-	spin_unlock(&io_lock);
-}
-
-static int davinci_wdt_open(struct inode *inode, struct file *file)
-{
-	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
-		return -EBUSY;
-
-	wdt_enable();
-
-	return nonseekable_open(inode, file);
+	return 0;
 }
 
-static ssize_t
-davinci_wdt_write(struct file *file, const char *data, size_t len,
-		  loff_t *ppos)
+static int davinci_wdt_ping(struct watchdog_device *wdd)
 {
-	if (len)
-		wdt_service();
-
-	return len;
+	/* put watchdog in service state */
+	iowrite32(WDKEY_SEQ0, wdt_base + WDTCR);
+	/* put watchdog in active state */
+	iowrite32(WDKEY_SEQ1, wdt_base + WDTCR);
+	return 0;
 }
 
-static const struct watchdog_info ident = {
+static const struct watchdog_info davinci_wdt_info = {
 	.options = WDIOF_KEEPALIVEPING,
 	.identity = "DaVinci Watchdog",
 };
 
-static long davinci_wdt_ioctl(struct file *file,
-					unsigned int cmd, unsigned long arg)
-{
-	int ret = -ENOTTY;
-
-	switch (cmd) {
-	case WDIOC_GETSUPPORT:
-		ret = copy_to_user((struct watchdog_info *)arg, &ident,
-				   sizeof(ident)) ? -EFAULT : 0;
-		break;
-
-	case WDIOC_GETSTATUS:
-	case WDIOC_GETBOOTSTATUS:
-		ret = put_user(0, (int *)arg);
-		break;
-
-	case WDIOC_KEEPALIVE:
-		wdt_service();
-		ret = 0;
-		break;
-
-	case WDIOC_GETTIMEOUT:
-		ret = put_user(heartbeat, (int *)arg);
-		break;
-	}
-	return ret;
-}
-
-static int davinci_wdt_release(struct inode *inode, struct file *file)
-{
-	wdt_service();
-	clear_bit(WDT_IN_USE, &wdt_status);
-
-	return 0;
-}
-
-static const struct file_operations davinci_wdt_fops = {
-	.owner = THIS_MODULE,
-	.llseek = no_llseek,
-	.write = davinci_wdt_write,
-	.unlocked_ioctl = davinci_wdt_ioctl,
-	.open = davinci_wdt_open,
-	.release = davinci_wdt_release,
-};
-
-static struct miscdevice davinci_wdt_miscdev = {
-	.minor = WATCHDOG_MINOR,
-	.name = "watchdog",
-	.fops = &davinci_wdt_fops,
+static const struct watchdog_ops davinci_wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= davinci_wdt_start,
+	.stop		= davinci_wdt_ping,
+	.ping		= davinci_wdt_ping,
 };
 
 static int davinci_wdt_probe(struct platform_device *pdev)
@@ -204,6 +121,7 @@ static int davinci_wdt_probe(struct platform_device *pdev)
 	int ret = 0;
 	struct device *dev = &pdev->dev;
 	struct resource  *wdt_mem;
+	struct watchdog_device *wdd;
 
 	wdt_clk = devm_clk_get(dev, NULL);
 	if (WARN_ON(IS_ERR(wdt_clk)))
@@ -211,29 +129,34 @@ static int davinci_wdt_probe(struct platform_device *pdev)
 
 	clk_prepare_enable(wdt_clk);
 
-	if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
-		heartbeat = DEFAULT_HEARTBEAT;
+	wdd			= &wdt_wdd;
+	wdd->info		= &davinci_wdt_info;
+	wdd->ops		= &davinci_wdt_ops;
+	wdd->min_timeout	= 1;
+	wdd->max_timeout	= MAX_HEARTBEAT;
+	wdd->timeout		= DEFAULT_HEARTBEAT;
+
+	watchdog_init_timeout(wdd, heartbeat, dev);
+
+	dev_info(dev, "heartbeat %d sec\n", wdd->timeout);
 
-	dev_info(dev, "heartbeat %d sec\n", heartbeat);
+	watchdog_set_nowayout(wdd, 1);
 
 	wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	wdt_base = devm_ioremap_resource(dev, wdt_mem);
 	if (IS_ERR(wdt_base))
 		return PTR_ERR(wdt_base);
 
-	ret = misc_register(&davinci_wdt_miscdev);
-	if (ret < 0) {
-		dev_err(dev, "cannot register misc device\n");
-	} else {
-		set_bit(WDT_DEVICE_INITED, &wdt_status);
-	}
+	ret = watchdog_register_device(wdd);
+	if (ret < 0)
+		dev_err(dev, "cannot register watchdog device\n");
 
 	return ret;
 }
 
 static int davinci_wdt_remove(struct platform_device *pdev)
 {
-	misc_deregister(&davinci_wdt_miscdev);
+	watchdog_unregister_device(&wdt_wdd);
 	clk_disable_unprepare(wdt_clk);
 
 	return 0;