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
32 #include <asm/hardware.h>
33 #include <asm/uaccess.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 /* Can't seek (pwrite) on this device */
111 if (*ppos != file->f_pos)
112 return -ESPIPE;
113
114 if (len) {
115 if (!nowayout) {
116 size_t i;
117
118 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
119
120 for (i = 0; i != len; i++) {
121 char c;
122
123 if (get_user(c, data + i))
124 return -EFAULT;
125
126 if (c == 'V')
127 set_bit(WDT_OK_TO_CLOSE, &wdt_status);
128 else
129 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
130 }
131 }
132 wdt_keepalive();
133 }
134
135 return len;
136 }
137
138 static struct watchdog_info ident = {
139 .options = WDIOF_CARDRESET | WDIOF_MAGICCLOSE,
140 .identity = "EP93xx Watchdog",
141 };
142
143 static int
144 ep93xx_wdt_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
145 unsigned long arg)
146 {
147 int ret = -ENOIOCTLCMD;
148
149 switch (cmd) {
150 case WDIOC_GETSUPPORT:
151 ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
152 sizeof(ident)) ? -EFAULT : 0;
153 break;
154
155 case WDIOC_GETSTATUS:
156 ret = put_user(0, (int __user *)arg);
157 break;
158
159 case WDIOC_GETBOOTSTATUS:
160 ret = put_user(boot_status, (int __user *)arg);
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 case WDIOC_KEEPALIVE:
169 wdt_keepalive();
170 ret = 0;
171 break;
172 }
173 return ret;
174 }
175
176 static int ep93xx_wdt_release(struct inode *inode, struct file *file)
177 {
178 if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
179 wdt_shutdown();
180 else
181 printk(KERN_CRIT PFX "Device closed unexpectedly - "
182 "timer will not stop\n");
183
184 clear_bit(WDT_IN_USE, &wdt_status);
185 clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
186
187 return 0;
188 }
189
190 static struct file_operations ep93xx_wdt_fops = {
191 .owner = THIS_MODULE,
192 .write = ep93xx_wdt_write,
193 .ioctl = ep93xx_wdt_ioctl,
194 .open = ep93xx_wdt_open,
195 .release = ep93xx_wdt_release,
196 };
197
198 static struct miscdevice ep93xx_wdt_miscdev = {
199 .minor = WATCHDOG_MINOR,
200 .name = "watchdog",
201 .fops = &ep93xx_wdt_fops,
202 };
203
204 static void ep93xx_timer_ping(unsigned long data)
205 {
206 if (time_before(jiffies, next_heartbeat))
207 wdt_ping();
208
209 /* Re-set the timer interval */
210 mod_timer(&timer, jiffies + WDT_INTERVAL);
211 }
212
213 static int __init ep93xx_wdt_init(void)
214 {
215 int err;
216
217 err = misc_register(&ep93xx_wdt_miscdev);
218
219 boot_status = __raw_readl(EP93XX_WDT_WATCHDOG) & 0x01 ? 1 : 0;
220
221 printk(KERN_INFO PFX "EP93XX watchdog, driver version "
222 WDT_VERSION "%s\n",
223 (__raw_readl(EP93XX_WDT_WATCHDOG) & 0x08)
224 ? " (nCS1 disable detected)" : "");
225
226 if (timeout < 1 || timeout > 3600) {
227 timeout = WDT_TIMEOUT;
228 printk(KERN_INFO PFX
229 "timeout value must be 1<=x<=3600, using %d\n",
230 timeout);
231 }
232
233 setup_timer(&timer, ep93xx_timer_ping, 1);
234 return err;
235 }
236
237 static void __exit ep93xx_wdt_exit(void)
238 {
239 wdt_shutdown();
240 misc_deregister(&ep93xx_wdt_miscdev);
241 }
242
243 module_init(ep93xx_wdt_init);
244 module_exit(ep93xx_wdt_exit);
245
246 module_param(nowayout, int, 0);
247 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
248
249 module_param(timeout, int, 0);
250 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
251
252 MODULE_AUTHOR("Ray Lehtiniemi <rayl@mail.com>,"
253 "Alessandro Zummo <a.zummo@towertech.it>");
254 MODULE_DESCRIPTION("EP93xx Watchdog");
255 MODULE_LICENSE("GPL");
256 MODULE_VERSION(WDT_VERSION);
257 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
258
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