[PATCH] cirrus ep93xx watchdog driver

Add a driver for the on-chip watchdog on the cirrus ep93xx series of ARM
CPUs.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 257 insertions, 0 deletions

diff --git a/drivers/char/watchdog/ep93xx_wdt.c b/drivers/char/watchdog/ep93xx_wdt.c
new file mode 100644
index 000000000000..9021dbb78299
--- /dev/null
+++ b/drivers/char/watchdog/ep93xx_wdt.c
@@ -0,0 +1,257 @@
+/*
+ * Watchdog driver for Cirrus Logic EP93xx family of devices.
+ *
+ * Copyright (c) 2004 Ray Lehtiniemi
+ * Copyright (c) 2006 Tower Technologies
+ * Based on ep93xx driver, bits from alim7101_wdt.c
+ *
+ * Authors: Ray Lehtiniemi <rayl@mail.com>,
+ *	Alessandro Zummo <a.zummo@towertech.it>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ *
+ * This watchdog fires after 250msec, which is a too short interval
+ * for us to rely on the user space daemon alone. So we ping the
+ * wdt each ~200msec and eventually stop doing it if the user space
+ * daemon dies.
+ *
+ * TODO:
+ *
+ *	- Test last reset from watchdog status
+ *	- Add a few missing ioctls
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/timer.h>
+
+#include <asm/hardware.h>
+#include <asm/uaccess.h>
+
+#define WDT_VERSION	"0.3"
+#define PFX		"ep93xx_wdt: "
+
+/* default timeout (secs) */
+#define WDT_TIMEOUT 30
+
+static int nowayout = WATCHDOG_NOWAYOUT;
+static int timeout = WDT_TIMEOUT;
+
+static struct timer_list timer;
+static unsigned long next_heartbeat;
+static unsigned long wdt_status;
+static unsigned long boot_status;
+
+#define WDT_IN_USE		0
+#define WDT_OK_TO_CLOSE		1
+
+#define EP93XX_WDT_REG(x)	(EP93XX_WATCHDOG_BASE + (x))
+#define EP93XX_WDT_WATCHDOG	EP93XX_WDT_REG(0x00)
+#define EP93XX_WDT_WDSTATUS	EP93XX_WDT_REG(0x04)
+
+/* reset the wdt every ~200ms */
+#define WDT_INTERVAL (HZ/5)
+
+static void wdt_enable(void)
+{
+	__raw_writew(0xaaaa, EP93XX_WDT_WATCHDOG);
+}
+
+static void wdt_disable(void)
+{
+	__raw_writew(0xaa55, EP93XX_WDT_WATCHDOG);
+}
+
+static inline void wdt_ping(void)
+{
+	__raw_writew(0x5555, EP93XX_WDT_WATCHDOG);
+}
+
+static void wdt_startup(void)
+{
+	next_heartbeat = jiffies + (timeout * HZ);
+
+	wdt_enable();
+	mod_timer(&timer, jiffies + WDT_INTERVAL);
+}
+
+static void wdt_shutdown(void)
+{
+	del_timer_sync(&timer);
+	wdt_disable();
+}
+
+static void wdt_keepalive(void)
+{
+	/* user land ping */
+	next_heartbeat = jiffies + (timeout * HZ);
+}
+
+static int ep93xx_wdt_open(struct inode *inode, struct file *file)
+{
+	if (test_and_set_bit(WDT_IN_USE, &wdt_status))
+		return -EBUSY;
+
+	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
+
+	wdt_startup();
+
+	return nonseekable_open(inode, file);
+}
+
+static ssize_t
+ep93xx_wdt_write(struct file *file, const char __user *data, size_t len,
+		 loff_t *ppos)
+{
+	/* Can't seek (pwrite) on this device */
+	if (*ppos != file->f_pos)
+		return -ESPIPE;
+
+	if (len) {
+		if (!nowayout) {
+			size_t i;
+
+			clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
+
+			for (i = 0; i != len; i++) {
+				char c;
+
+				if (get_user(c, data + i))
+					return -EFAULT;
+
+				if (c == 'V')
+					set_bit(WDT_OK_TO_CLOSE, &wdt_status);
+				else
+					clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
+			}
+		}
+		wdt_keepalive();
+	}
+
+	return len;
+}
+
+static struct watchdog_info ident = {
+	.options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE,
+	.identity = "EP93xx Watchdog",
+};
+
+static int
+ep93xx_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
+		 unsigned long arg)
+{
+	int ret = -ENOIOCTLCMD;
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
+				sizeof(ident)) ? -EFAULT : 0;
+		break;
+
+	case WDIOC_GETSTATUS:
+		ret = put_user(0, (int __user *)arg);
+		break;
+
+	case WDIOC_GETBOOTSTATUS:
+		ret = put_user(boot_status, (int __user *)arg);
+		break;
+
+	case WDIOC_GETTIMEOUT:
+		/* actually, it is 0.250 seconds.... */
+		ret = put_user(1, (int __user *)arg);
+		break;
+
+	case WDIOC_KEEPALIVE:
+		wdt_keepalive();
+		ret = 0;
+		break;
+	}
+	return ret;
+}
+
+static int ep93xx_wdt_release(struct inode *inode, struct file *file)
+{
+	if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
+		wdt_shutdown();
+	else
+		printk(KERN_CRIT PFX "Device closed unexpectedly - "
+			"timer will not stop\n");
+
+	clear_bit(WDT_IN_USE, &wdt_status);
+	clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
+
+	return 0;
+}
+
+static struct file_operations ep93xx_wdt_fops = {
+	.owner		= THIS_MODULE,
+	.write		= ep93xx_wdt_write,
+	.ioctl		= ep93xx_wdt_ioctl,
+	.open		= ep93xx_wdt_open,
+	.release	= ep93xx_wdt_release,
+};
+
+static struct miscdevice ep93xx_wdt_miscdev = {
+	.minor		= WATCHDOG_MINOR,
+	.name		= "watchdog",
+	.fops		= &ep93xx_wdt_fops,
+};
+
+static void ep93xx_timer_ping(unsigned long data)
+{
+	if (time_before(jiffies, next_heartbeat))
+		wdt_ping();
+
+	/* Re-set the timer interval */
+	mod_timer(&timer, jiffies + WDT_INTERVAL);
+}
+
+static int __init ep93xx_wdt_init(void)
+{
+	int err;
+
+	err = misc_register(&ep93xx_wdt_miscdev);
+
+	boot_status = __raw_readl(EP93XX_WDT_WATCHDOG) & 0x01 ? 1 : 0;
+
+	printk(KERN_INFO PFX "EP93XX watchdog, driver version "
+		WDT_VERSION "%s\n",
+		(__raw_readl(EP93XX_WDT_WATCHDOG) & 0x08)
+		? " (nCS1 disable detected)" : "");
+
+	if (timeout < 1 || timeout > 3600) {
+		timeout = WDT_TIMEOUT;
+		printk(KERN_INFO PFX
+			"timeout value must be 1<=x<=3600, using %d\n",
+			timeout);
+	}
+
+	setup_timer(&timer, ep93xx_timer_ping, 1);
+	return err;
+}
+
+static void __exit ep93xx_wdt_exit(void)
+{
+	wdt_shutdown();
+	misc_deregister(&ep93xx_wdt_miscdev);
+}
+
+module_init(ep93xx_wdt_init);
+module_exit(ep93xx_wdt_exit);
+
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
+
+module_param(timeout, int, 0);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
+
+MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>,"
+		"Alessandro Zummo <a.zummo@towertech.it>");
+MODULE_DESCRIPTION("EP93xx Watchdog");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(WDT_VERSION);
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);