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 #include <linux/module.h>
28 #include <linux/miscdevice.h>
29 #include <linux/watchdog.h>
30 #include <linux/timer.h>
31 #include <linux/uaccess.h>
32 #include <mach/hardware.h>
34 #define WDT_VERSION "0.3"
35 #define PFX "ep93xx_wdt: "
37 /* default timeout (secs) */
38 #define WDT_TIMEOUT 30
40 static int nowayout = WATCHDOG_NOWAYOUT;
41 static int timeout = WDT_TIMEOUT;
43 static struct timer_list timer;
44 static unsigned long next_heartbeat;
45 static unsigned long wdt_status;
46 static unsigned long boot_status;
49 #define WDT_OK_TO_CLOSE 1
51 #define EP93XX_WDT_REG(x) (EP93XX_WATCHDOG_BASE + (x))
52 #define EP93XX_WDT_WATCHDOG EP93XX_WDT_REG(0x00)
53 #define EP93XX_WDT_WDSTATUS EP93XX_WDT_REG(0x04)
55 /* reset the wdt every ~200ms */
56 #define WDT_INTERVAL (HZ/5)
58 static void wdt_enable(void)
60 __raw_writew(0xaaaa, EP93XX_WDT_WATCHDOG);
63 static void wdt_disable(void)
65 __raw_writew(0xaa55, EP93XX_WDT_WATCHDOG);
68 static inline void wdt_ping(void)
70 __raw_writew(0x5555, EP93XX_WDT_WATCHDOG);
73 static void wdt_startup(void)
75 next_heartbeat = jiffies + (timeout * HZ);
78 mod_timer(&timer, jiffies + WDT_INTERVAL);
81 static void wdt_shutdown(void)
83 del_timer_sync(&timer);
87 static void wdt_keepalive(void)
90 next_heartbeat = jiffies + (timeout * HZ);
93 static int ep93xx_wdt_open(struct inode *inode, struct file *file)
95 if (test_and_set_bit(WDT_IN_USE, &wdt_status))
98 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
102 return nonseekable_open(inode, file);
106 ep93xx_wdt_write(struct file *file, const char __user *data, size_t len,
113 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
115 for (i = 0; i != len; i++) {
118 if (get_user(c, data + i))
122 set_bit(WDT_OK_TO_CLOSE, &wdt_status);
124 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
133 static struct watchdog_info ident = {
134 .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE,
135 .identity = "EP93xx Watchdog",
138 static long ep93xx_wdt_ioctl(struct file *file,
139 unsigned int cmd, unsigned long arg)
144 case WDIOC_GETSUPPORT:
145 ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
146 sizeof(ident)) ? -EFAULT : 0;
149 case WDIOC_GETSTATUS:
150 ret = put_user(0, (int __user *)arg);
153 case WDIOC_GETBOOTSTATUS:
154 ret = put_user(boot_status, (int __user *)arg);
157 case WDIOC_KEEPALIVE:
162 case WDIOC_GETTIMEOUT:
163 /* actually, it is 0.250 seconds.... */
164 ret = put_user(1, (int __user *)arg);
170 static int ep93xx_wdt_release(struct inode *inode, struct file *file)
172 if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
176 "Device closed unexpectedly - timer will not stop\n");
178 clear_bit(WDT_IN_USE, &wdt_status);
179 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
184 static const struct file_operations ep93xx_wdt_fops = {
185 .owner = THIS_MODULE,
186 .write = ep93xx_wdt_write,
187 .unlocked_ioctl = ep93xx_wdt_ioctl,
188 .open = ep93xx_wdt_open,
189 .release = ep93xx_wdt_release,
192 static struct miscdevice ep93xx_wdt_miscdev = {
193 .minor = WATCHDOG_MINOR,
195 .fops = &ep93xx_wdt_fops,
198 static void ep93xx_timer_ping(unsigned long data)
200 if (time_before(jiffies, next_heartbeat))
203 /* Re-set the timer interval */
204 mod_timer(&timer, jiffies + WDT_INTERVAL);
207 static int __init ep93xx_wdt_init(void)
211 err = misc_register(&ep93xx_wdt_miscdev);
213 boot_status = __raw_readl(EP93XX_WDT_WATCHDOG) & 0x01 ? 1 : 0;
215 printk(KERN_INFO PFX "EP93XX watchdog, driver version "
217 (__raw_readl(EP93XX_WDT_WATCHDOG) & 0x08)
218 ? " (nCS1 disable detected)" : "");
220 if (timeout < 1 || timeout > 3600) {
221 timeout = WDT_TIMEOUT;
223 "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(WATCHDOG_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);