726b7df61fd08b366a728fb5be0c793235b4d585
[sfrench/cifs-2.6.git] / drivers / watchdog / ep93xx_wdt.c
1 /*
2  * Watchdog driver for Cirrus Logic EP93xx family of devices.
3  *
4  * Copyright (c) 2004 Ray Lehtiniemi
5  * Copyright (c) 2006 Tower Technologies
6  * Based on ep93xx driver, bits from alim7101_wdt.c
7  *
8  * Authors: Ray Lehtiniemi <rayl@mail.com>,
9  *      Alessandro Zummo <a.zummo@towertech.it>
10  *
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.
14  *
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
18  * daemon dies.
19  *
20  * TODO:
21  *
22  *      - Test last reset from watchdog status
23  *      - Add a few missing ioctls
24  */
25
26 #include <linux/module.h>
27 #include <linux/fs.h>
28 #include <linux/miscdevice.h>
29 #include <linux/watchdog.h>
30 #include <linux/timer.h>
31 #include <linux/uaccess.h>
32 #include <linux/io.h>
33 #include <mach/hardware.h>
34
35 #define WDT_VERSION     "0.3"
36 #define PFX             "ep93xx_wdt: "
37
38 /* default timeout (secs) */
39 #define WDT_TIMEOUT 30
40
41 static int nowayout = WATCHDOG_NOWAYOUT;
42 static int timeout = WDT_TIMEOUT;
43
44 static struct timer_list timer;
45 static unsigned long next_heartbeat;
46 static unsigned long wdt_status;
47 static unsigned long boot_status;
48
49 #define WDT_IN_USE              0
50 #define WDT_OK_TO_CLOSE         1
51
52 #define EP93XX_WDT_REG(x)       (EP93XX_WATCHDOG_BASE + (x))
53 #define EP93XX_WDT_WATCHDOG     EP93XX_WDT_REG(0x00)
54 #define EP93XX_WDT_WDSTATUS     EP93XX_WDT_REG(0x04)
55
56 /* reset the wdt every ~200ms */
57 #define WDT_INTERVAL (HZ/5)
58
59 static void wdt_enable(void)
60 {
61         __raw_writew(0xaaaa, EP93XX_WDT_WATCHDOG);
62 }
63
64 static void wdt_disable(void)
65 {
66         __raw_writew(0xaa55, EP93XX_WDT_WATCHDOG);
67 }
68
69 static inline void wdt_ping(void)
70 {
71         __raw_writew(0x5555, EP93XX_WDT_WATCHDOG);
72 }
73
74 static void wdt_startup(void)
75 {
76         next_heartbeat = jiffies + (timeout * HZ);
77
78         wdt_enable();
79         mod_timer(&timer, jiffies + WDT_INTERVAL);
80 }
81
82 static void wdt_shutdown(void)
83 {
84         del_timer_sync(&timer);
85         wdt_disable();
86 }
87
88 static void wdt_keepalive(void)
89 {
90         /* user land ping */
91         next_heartbeat = jiffies + (timeout * HZ);
92 }
93
94 static int ep93xx_wdt_open(struct inode *inode, struct file *file)
95 {
96         if (test_and_set_bit(WDT_IN_USE, &wdt_status))
97                 return -EBUSY;
98
99         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
100
101         wdt_startup();
102
103         return nonseekable_open(inode, file);
104 }
105
106 static ssize_t
107 ep93xx_wdt_write(struct file *file, const char __user *data, size_t len,
108                  loff_t *ppos)
109 {
110         if (len) {
111                 if (!nowayout) {
112                         size_t i;
113
114                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
115
116                         for (i = 0; i != len; i++) {
117                                 char c;
118
119                                 if (get_user(c, data + i))
120                                         return -EFAULT;
121
122                                 if (c == 'V')
123                                         set_bit(WDT_OK_TO_CLOSE, &wdt_status);
124                                 else
125                                         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
126                         }
127                 }
128                 wdt_keepalive();
129         }
130
131         return len;
132 }
133
134 static const struct watchdog_info ident = {
135         .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE,
136         .identity = "EP93xx Watchdog",
137 };
138
139 static long ep93xx_wdt_ioctl(struct file *file,
140                                         unsigned int cmd, unsigned long arg)
141 {
142         int ret = -ENOTTY;
143
144         switch (cmd) {
145         case WDIOC_GETSUPPORT:
146                 ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
147                                 sizeof(ident)) ? -EFAULT : 0;
148                 break;
149
150         case WDIOC_GETSTATUS:
151                 ret = put_user(0, (int __user *)arg);
152                 break;
153
154         case WDIOC_GETBOOTSTATUS:
155                 ret = put_user(boot_status, (int __user *)arg);
156                 break;
157
158         case WDIOC_KEEPALIVE:
159                 wdt_keepalive();
160                 ret = 0;
161                 break;
162
163         case WDIOC_GETTIMEOUT:
164                 /* actually, it is 0.250 seconds.... */
165                 ret = put_user(1, (int __user *)arg);
166                 break;
167         }
168         return ret;
169 }
170
171 static int ep93xx_wdt_release(struct inode *inode, struct file *file)
172 {
173         if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
174                 wdt_shutdown();
175         else
176                 printk(KERN_CRIT PFX
177                         "Device closed unexpectedly - timer will not stop\n");
178
179         clear_bit(WDT_IN_USE, &wdt_status);
180         clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
181
182         return 0;
183 }
184
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,
191         .llseek         = no_llseek,
192 };
193
194 static struct miscdevice ep93xx_wdt_miscdev = {
195         .minor          = WATCHDOG_MINOR,
196         .name           = "watchdog",
197         .fops           = &ep93xx_wdt_fops,
198 };
199
200 static void ep93xx_timer_ping(unsigned long data)
201 {
202         if (time_before(jiffies, next_heartbeat))
203                 wdt_ping();
204
205         /* Re-set the timer interval */
206         mod_timer(&timer, jiffies + WDT_INTERVAL);
207 }
208
209 static int __init ep93xx_wdt_init(void)
210 {
211         int err;
212
213         err = misc_register(&ep93xx_wdt_miscdev);
214
215         boot_status = __raw_readl(EP93XX_WDT_WATCHDOG) & 0x01 ? 1 : 0;
216
217         printk(KERN_INFO PFX "EP93XX watchdog, driver version "
218                 WDT_VERSION "%s\n",
219                 (__raw_readl(EP93XX_WDT_WATCHDOG) & 0x08)
220                 ? " (nCS1 disable detected)" : "");
221
222         if (timeout < 1 || timeout > 3600) {
223                 timeout = WDT_TIMEOUT;
224                 printk(KERN_INFO PFX
225                         "timeout value must be 1<=x<=3600, using %d\n",
226                         timeout);
227         }
228
229         setup_timer(&timer, ep93xx_timer_ping, 1);
230         return err;
231 }
232
233 static void __exit ep93xx_wdt_exit(void)
234 {
235         wdt_shutdown();
236         misc_deregister(&ep93xx_wdt_miscdev);
237 }
238
239 module_init(ep93xx_wdt_init);
240 module_exit(ep93xx_wdt_exit);
241
242 module_param(nowayout, int, 0);
243 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
244
245 module_param(timeout, int, 0);
246 MODULE_PARM_DESC(timeout,
247         "Watchdog timeout in seconds. (1<=timeout<=3600, default="
248                                 __MODULE_STRING(WDT_TIMEOUT) ")");
249
250 MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>,"
251                 "Alessandro Zummo <a.zummo@towertech.it>");
252 MODULE_DESCRIPTION("EP93xx Watchdog");
253 MODULE_LICENSE("GPL");
254 MODULE_VERSION(WDT_VERSION);
255 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);