[WATCHDOG] Add AT91SAM9X watchdog

Add a driver for the watchdog timer embedded into AT91SAM9X chips.

Signed-off-by: Renaud Cerrato <r.cerrato@til-technologies.fr>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

1 files changed, 328 insertions, 0 deletions

diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c
new file mode 100644
index 000000000000..b4babfc31586
--- /dev/null
+++ b/drivers/watchdog/at91sam9_wdt.c
@@ -0,0 +1,328 @@
+/*
+ * Watchdog driver for Atmel AT91SAM9x processors.
+ *
+ * Copyright (C) 2008 Renaud CERRATO r.cerrato@til-technologies.fr
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+/*
+ * The Watchdog Timer Mode Register can be only written to once. If the
+ * timeout need to be set from Linux, be sure that the bootstrap or the
+ * bootloader doesn't write to this register.
+ */
+
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/platform_device.h>
+#include <linux/types.h>
+#include <linux/watchdog.h>
+#include <linux/jiffies.h>
+#include <linux/timer.h>
+#include <linux/bitops.h>
+#include <linux/uaccess.h>
+
+#include <asm/arch/at91_wdt.h>
+
+#define DRV_NAME "AT91SAM9 Watchdog"
+
+/* AT91SAM9 watchdog runs a 12bit counter @ 256Hz,
+ * use this to convert a watchdog
+ * value from/to milliseconds.
+ */
+#define ms_to_ticks(t)	(((t << 8) / 1000) - 1)
+#define ticks_to_ms(t)	(((t + 1) * 1000) >> 8)
+
+/* Hardware timeout in seconds */
+#define WDT_HW_TIMEOUT 2
+
+/* Timer heartbeat (500ms) */
+#define WDT_TIMEOUT	(HZ/2)
+
+/* User land timeout */
+#define WDT_HEARTBEAT 15
+static int heartbeat = WDT_HEARTBEAT;
+module_param(heartbeat, int, 0);
+MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds. "
+	"(default = " __MODULE_STRING(WDT_HEARTBEAT) ")");
+
+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) ")");
+
+static void at91_ping(unsigned long data);
+
+static struct {
+	unsigned long next_heartbeat;	/* the next_heartbeat for the timer */
+	unsigned long open;
+	char expect_close;
+	struct timer_list timer;	/* The timer that pings the watchdog */
+} at91wdt_private;
+
+/* ......................................................................... */
+
+
+/*
+ * Reload the watchdog timer.  (ie, pat the watchdog)
+ */
+static inline void at91_wdt_reset(void)
+{
+	at91_sys_write(AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
+}
+
+/*
+ * Timer tick
+ */
+static void at91_ping(unsigned long data)
+{
+	if (time_before(jiffies, at91wdt_private.next_heartbeat) ||
+			(!nowayout && !at91wdt_private.open)) {
+		at91_wdt_reset();
+		mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
+	} else
+		printk(KERN_CRIT DRV_NAME": I will reset your machine !\n");
+}
+
+/*
+ * Watchdog device is opened, and watchdog starts running.
+ */
+static int at91_wdt_open(struct inode *inode, struct file *file)
+{
+	if (test_and_set_bit(0, &at91wdt_private.open))
+		return -EBUSY;
+
+	at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
+	mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
+
+	return nonseekable_open(inode, file);
+}
+
+/*
+ * Close the watchdog device.
+ */
+static int at91_wdt_close(struct inode *inode, struct file *file)
+{
+	clear_bit(0, &at91wdt_private.open);
+
+	/* stop internal ping */
+	if (!at91wdt_private.expect_close)
+		del_timer(&at91wdt_private.timer);
+
+	at91wdt_private.expect_close = 0;
+	return 0;
+}
+
+/*
+ * Set the watchdog time interval in 1/256Hz (write-once)
+ * Counter is 12 bit.
+ */
+static int at91_wdt_settimeout(unsigned int timeout)
+{
+	unsigned int reg;
+	unsigned int mr;
+
+	/* Check if disabled */
+	mr = at91_sys_read(AT91_WDT_MR);
+	if (mr & AT91_WDT_WDDIS) {
+		printk(KERN_ERR DRV_NAME": sorry, watchdog is disabled\n");
+		return -EIO;
+	}
+
+	/*
+	 * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
+	 *
+	 * Since WDV is a 12-bit counter, the maximum period is
+	 * 4096 / 256 = 16 seconds.
+	 */
+	reg = AT91_WDT_WDRSTEN	/* causes watchdog reset */
+		/* | AT91_WDT_WDRPROC	causes processor reset only */
+		| AT91_WDT_WDDBGHLT	/* disabled in debug mode */
+		| AT91_WDT_WDD		/* restart at any time */
+		| (timeout & AT91_WDT_WDV);  /* timer value */
+	at91_sys_write(AT91_WDT_MR, reg);
+
+	return 0;
+}
+
+static const struct watchdog_info at91_wdt_info = {
+	.identity	= DRV_NAME,
+	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
+};
+
+/*
+ * Handle commands from user-space.
+ */
+static long at91_wdt_ioctl(struct file *file,
+		unsigned int cmd, unsigned long arg)
+{
+	void __user *argp = (void __user *)arg;
+	int __user *p = argp;
+	int new_value;
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		return copy_to_user(argp, &at91_wdt_info,
+				    sizeof(at91_wdt_info)) ? -EFAULT : 0;
+
+	case WDIOC_GETSTATUS:
+	case WDIOC_GETBOOTSTATUS:
+		return put_user(0, p);
+
+	case WDIOC_KEEPALIVE:
+		at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
+		return 0;
+
+	case WDIOC_SETTIMEOUT:
+		if (get_user(new_value, p))
+			return -EFAULT;
+
+		heartbeat = new_value;
+		at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
+
+		return put_user(new_value, p);  /* return current value */
+
+	case WDIOC_GETTIMEOUT:
+		return put_user(heartbeat, p);
+	}
+	return -ENOTTY;
+}
+
+/*
+ * Pat the watchdog whenever device is written to.
+ */
+static ssize_t at91_wdt_write(struct file *file, const char *data, size_t len,
+      loff_t *ppos)
+{
+	if (!len)
+		return 0;
+
+	/* Scan for magic character */
+	if (!nowayout) {
+		size_t i;
+
+		at91wdt_private.expect_close = 0;
+
+		for (i = 0; i < len; i++) {
+			char c;
+			if (get_user(c, data + i))
+				return -EFAULT;
+			if (c == 'V') {
+				at91wdt_private.expect_close = 42;
+				break;
+			}
+		}
+	}
+
+	at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
+
+	return len;
+}
+
+/* ......................................................................... */
+
+static const struct file_operations at91wdt_fops = {
+	.owner			= THIS_MODULE,
+	.llseek			= no_llseek,
+	.unlocked_ioctl	= at91_wdt_ioctl,
+	.open			= at91_wdt_open,
+	.release		= at91_wdt_close,
+	.write			= at91_wdt_write,
+};
+
+static struct miscdevice at91wdt_miscdev = {
+	.minor		= WATCHDOG_MINOR,
+	.name		= "watchdog",
+	.fops		= &at91wdt_fops,
+};
+
+static int __init at91wdt_probe(struct platform_device *pdev)
+{
+	int res;
+
+	if (at91wdt_miscdev.parent)
+		return -EBUSY;
+	at91wdt_miscdev.parent = &pdev->dev;
+
+	/* Set watchdog */
+	res = at91_wdt_settimeout(ms_to_ticks(WDT_HW_TIMEOUT * 1000));
+	if (res)
+		return res;
+
+	res = misc_register(&at91wdt_miscdev);
+	if (res)
+		return res;
+
+	at91wdt_private.next_heartbeat = jiffies + heartbeat * HZ;
+	setup_timer(&at91wdt_private.timer, at91_ping, 0);
+	mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
+
+	printk(KERN_INFO DRV_NAME " enabled (heartbeat=%d sec, nowayout=%d)\n",
+		heartbeat, nowayout);
+
+	return 0;
+}
+
+static int __exit at91wdt_remove(struct platform_device *pdev)
+{
+	int res;
+
+	res = misc_deregister(&at91wdt_miscdev);
+	if (!res)
+		at91wdt_miscdev.parent = NULL;
+
+	return res;
+}
+
+#ifdef CONFIG_PM
+
+static int at91wdt_suspend(struct platform_device *pdev, pm_message_t message)
+{
+	return 0;
+}
+
+static int at91wdt_resume(struct platform_device *pdev)
+{
+	return 0;
+}
+
+#else
+#define at91wdt_suspend	NULL
+#define at91wdt_resume	NULL
+#endif
+
+static struct platform_driver at91wdt_driver = {
+	.remove		= __exit_p(at91wdt_remove),
+	.suspend	= at91wdt_suspend,
+	.resume		= at91wdt_resume,
+	.driver		= {
+		.name	= "at91_wdt",
+		.owner	= THIS_MODULE,
+	},
+};
+
+static int __init at91sam_wdt_init(void)
+{
+	return platform_driver_probe(&at91wdt_driver, at91wdt_probe);
+}
+
+static void __exit at91sam_wdt_exit(void)
+{
+	platform_driver_unregister(&at91wdt_driver);
+}
+
+module_init(at91sam_wdt_init);
+module_exit(at91sam_wdt_exit);
+
+MODULE_AUTHOR("Renaud CERRATO <r.cerrato@til-technologies.fr>");
+MODULE_DESCRIPTION("Watchdog driver for Atmel AT91SAM9x processors");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);