2 * Watchdog driver for Cirrus Logic EP93xx family of devices.
4 * Copyright (c) 2004 Ray Lehtiniemi
5 * Copyright (c) 2006 Tower Technologies
6 * Based on ep93xx driver, bits from alim7101_wdt.c
8 * Authors: Ray Lehtiniemi <rayl@mail.com>,
9 * Alessandro Zummo <a.zummo@towertech.it>
11 * This file is licensed under the terms of the GNU General Public
12 * License version 2. This program is licensed "as is" without any
13 * warranty of any kind, whether express or implied.
15 * This watchdog fires after 250msec, which is a too short interval
16 * for us to rely on the user space daemon alone. So we ping the
17 * wdt each ~200msec and eventually stop doing it if the user space
22 * - Test last reset from watchdog status
23 * - Add a few missing ioctls
26 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
28 #include <linux/module.h>
30 #include <linux/miscdevice.h>
31 #include <linux/watchdog.h>
32 #include <linux/timer.h>
33 #include <linux/uaccess.h>
35 #include <mach/hardware.h>
37 #define WDT_VERSION "0.3"
39 /* default timeout (secs) */
40 #define WDT_TIMEOUT 30
42 static int nowayout = WATCHDOG_NOWAYOUT;
43 static int timeout = WDT_TIMEOUT;
45 static struct timer_list timer;
46 static unsigned long next_heartbeat;
47 static unsigned long wdt_status;
48 static unsigned long boot_status;
51 #define WDT_OK_TO_CLOSE 1
53 #define EP93XX_WDT_REG(x) (EP93XX_WATCHDOG_BASE + (x))
54 #define EP93XX_WDT_WATCHDOG EP93XX_WDT_REG(0x00)
55 #define EP93XX_WDT_WDSTATUS EP93XX_WDT_REG(0x04)
57 /* reset the wdt every ~200ms */
58 #define WDT_INTERVAL (HZ/5)
60 static void wdt_enable(void)
62 __raw_writew(0xaaaa, EP93XX_WDT_WATCHDOG);
65 static void wdt_disable(void)
67 __raw_writew(0xaa55, EP93XX_WDT_WATCHDOG);
70 static inline void wdt_ping(void)
72 __raw_writew(0x5555, EP93XX_WDT_WATCHDOG);
75 static void wdt_startup(void)
77 next_heartbeat = jiffies + (timeout * HZ);
80 mod_timer(&timer, jiffies + WDT_INTERVAL);
83 static void wdt_shutdown(void)
85 del_timer_sync(&timer);
89 static void wdt_keepalive(void)
92 next_heartbeat = jiffies + (timeout * HZ);
95 static int ep93xx_wdt_open(struct inode *inode, struct file *file)
97 if (test_and_set_bit(WDT_IN_USE, &wdt_status))
100 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
104 return nonseekable_open(inode, file);
108 ep93xx_wdt_write(struct file *file, const char __user *data, size_t len,
115 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
117 for (i = 0; i != len; i++) {
120 if (get_user(c, data + i))
124 set_bit(WDT_OK_TO_CLOSE, &wdt_status);
126 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
135 static const struct watchdog_info ident = {
136 .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE,
137 .identity = "EP93xx Watchdog",
140 static long ep93xx_wdt_ioctl(struct file *file,
141 unsigned int cmd, unsigned long arg)
146 case WDIOC_GETSUPPORT:
147 ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
148 sizeof(ident)) ? -EFAULT : 0;
151 case WDIOC_GETSTATUS:
152 ret = put_user(0, (int __user *)arg);
155 case WDIOC_GETBOOTSTATUS:
156 ret = put_user(boot_status, (int __user *)arg);
159 case WDIOC_KEEPALIVE:
164 case WDIOC_GETTIMEOUT:
165 /* actually, it is 0.250 seconds.... */
166 ret = put_user(1, (int __user *)arg);
172 static int ep93xx_wdt_release(struct inode *inode, struct file *file)
174 if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
177 pr_crit("Device closed unexpectedly - timer will not stop\n");
179 clear_bit(WDT_IN_USE, &wdt_status);
180 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
185 static const struct file_operations ep93xx_wdt_fops = {
186 .owner = THIS_MODULE,
187 .write = ep93xx_wdt_write,
188 .unlocked_ioctl = ep93xx_wdt_ioctl,
189 .open = ep93xx_wdt_open,
190 .release = ep93xx_wdt_release,
194 static struct miscdevice ep93xx_wdt_miscdev = {
195 .minor = WATCHDOG_MINOR,
197 .fops = &ep93xx_wdt_fops,
200 static void ep93xx_timer_ping(unsigned long data)
202 if (time_before(jiffies, next_heartbeat))
205 /* Re-set the timer interval */
206 mod_timer(&timer, jiffies + WDT_INTERVAL);
209 static int __init ep93xx_wdt_init(void)
213 err = misc_register(&ep93xx_wdt_miscdev);
215 boot_status = __raw_readl(EP93XX_WDT_WATCHDOG) & 0x01 ? 1 : 0;
217 pr_info("EP93XX watchdog, driver version " WDT_VERSION "%s\n",
218 (__raw_readl(EP93XX_WDT_WATCHDOG) & 0x08)
219 ? " (nCS1 disable detected)" : "");
221 if (timeout < 1 || timeout > 3600) {
222 timeout = WDT_TIMEOUT;
223 pr_info("timeout value must be 1<=x<=3600, using %d\n",
227 setup_timer(&timer, ep93xx_timer_ping, 1);
231 static void __exit ep93xx_wdt_exit(void)
234 misc_deregister(&ep93xx_wdt_miscdev);
237 module_init(ep93xx_wdt_init);
238 module_exit(ep93xx_wdt_exit);
240 module_param(nowayout, int, 0);
241 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
243 module_param(timeout, int, 0);
244 MODULE_PARM_DESC(timeout,
245 "Watchdog timeout in seconds. (1<=timeout<=3600, default="
246 __MODULE_STRING(WDT_TIMEOUT) ")");
248 MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>,"
249 "Alessandro Zummo <a.zummo@towertech.it>");
250 MODULE_DESCRIPTION("EP93xx Watchdog");
251 MODULE_LICENSE("GPL");
252 MODULE_VERSION(WDT_VERSION);
253 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);