Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/hskinnemoen...
[linux-2.6] / drivers / watchdog / wdt285.c
1 /*
2  *      Intel 21285 watchdog driver
3  *      Copyright (c) Phil Blundell <pb@nexus.co.uk>, 1998
4  *
5  *      based on
6  *
7  *      SoftDog 0.05:   A Software Watchdog Device
8  *
9  *      (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
10  *
11  *      This program is free software; you can redistribute it and/or
12  *      modify it under the terms of the GNU General Public License
13  *      as published by the Free Software Foundation; either version
14  *      2 of the License, or (at your option) any later version.
15  *
16  */
17
18 #include <linux/module.h>
19 #include <linux/moduleparam.h>
20 #include <linux/types.h>
21 #include <linux/kernel.h>
22 #include <linux/fs.h>
23 #include <linux/mm.h>
24 #include <linux/miscdevice.h>
25 #include <linux/watchdog.h>
26 #include <linux/reboot.h>
27 #include <linux/init.h>
28 #include <linux/interrupt.h>
29 #include <linux/uaccess.h>
30 #include <linux/irq.h>
31 #include <mach/hardware.h>
32
33 #include <asm/mach-types.h>
34 #include <asm/hardware/dec21285.h>
35
36 /*
37  * Define this to stop the watchdog actually rebooting the machine.
38  */
39 #undef ONLY_TESTING
40
41 static unsigned int soft_margin = 60;           /* in seconds */
42 static unsigned int reload;
43 static unsigned long timer_alive;
44
45 #ifdef ONLY_TESTING
46 /*
47  *      If the timer expires..
48  */
49 static void watchdog_fire(int irq, void *dev_id)
50 {
51         printk(KERN_CRIT "Watchdog: Would Reboot.\n");
52         *CSR_TIMER4_CNTL = 0;
53         *CSR_TIMER4_CLR = 0;
54 }
55 #endif
56
57 /*
58  *      Refresh the timer.
59  */
60 static void watchdog_ping(void)
61 {
62         *CSR_TIMER4_LOAD = reload;
63 }
64
65 /*
66  *      Allow only one person to hold it open
67  */
68 static int watchdog_open(struct inode *inode, struct file *file)
69 {
70         int ret;
71
72         if (*CSR_SA110_CNTL & (1 << 13))
73                 return -EBUSY;
74
75         if (test_and_set_bit(1, &timer_alive))
76                 return -EBUSY;
77
78         reload = soft_margin * (mem_fclk_21285 / 256);
79
80         *CSR_TIMER4_CLR = 0;
81         watchdog_ping();
82         *CSR_TIMER4_CNTL = TIMER_CNTL_ENABLE | TIMER_CNTL_AUTORELOAD
83                 | TIMER_CNTL_DIV256;
84
85 #ifdef ONLY_TESTING
86         ret = request_irq(IRQ_TIMER4, watchdog_fire, 0, "watchdog", NULL);
87         if (ret) {
88                 *CSR_TIMER4_CNTL = 0;
89                 clear_bit(1, &timer_alive);
90         }
91 #else
92         /*
93          * Setting this bit is irreversible; once enabled, there is
94          * no way to disable the watchdog.
95          */
96         *CSR_SA110_CNTL |= 1 << 13;
97
98         ret = 0;
99 #endif
100         nonseekable_open(inode, file);
101         return ret;
102 }
103
104 /*
105  *      Shut off the timer.
106  *      Note: if we really have enabled the watchdog, there
107  *      is no way to turn off.
108  */
109 static int watchdog_release(struct inode *inode, struct file *file)
110 {
111 #ifdef ONLY_TESTING
112         free_irq(IRQ_TIMER4, NULL);
113         clear_bit(1, &timer_alive);
114 #endif
115         return 0;
116 }
117
118 static ssize_t watchdog_write(struct file *file, const char __user *data,
119                               size_t len, loff_t *ppos)
120 {
121         /*
122          *      Refresh the timer.
123          */
124         if (len)
125                 watchdog_ping();
126
127         return len;
128 }
129
130 static const struct watchdog_info ident = {
131         .options        = WDIOF_SETTIMEOUT,
132         .identity       = "Footbridge Watchdog",
133 };
134
135 static long watchdog_ioctl(struct file *file, unsigned int cmd,
136                            unsigned long arg)
137 {
138         unsigned int new_margin;
139         int __user *int_arg = (int __user *)arg;
140         int ret = -ENOTTY;
141
142         switch (cmd) {
143         case WDIOC_GETSUPPORT:
144                 ret = 0;
145                 if (copy_to_user((void __user *)arg, &ident, sizeof(ident)))
146                         ret = -EFAULT;
147                 break;
148
149         case WDIOC_GETSTATUS:
150         case WDIOC_GETBOOTSTATUS:
151                 ret = put_user(0, int_arg);
152                 break;
153
154         case WDIOC_KEEPALIVE:
155                 watchdog_ping();
156                 ret = 0;
157                 break;
158
159         case WDIOC_SETTIMEOUT:
160                 ret = get_user(new_margin, int_arg);
161                 if (ret)
162                         break;
163
164                 /* Arbitrary, can't find the card's limits */
165                 if (new_margin < 0 || new_margin > 60) {
166                         ret = -EINVAL;
167                         break;
168                 }
169
170                 soft_margin = new_margin;
171                 reload = soft_margin * (mem_fclk_21285 / 256);
172                 watchdog_ping();
173                 /* Fall */
174         case WDIOC_GETTIMEOUT:
175                 ret = put_user(soft_margin, int_arg);
176                 break;
177         }
178         return ret;
179 }
180
181 static const struct file_operations watchdog_fops = {
182         .owner          = THIS_MODULE,
183         .llseek         = no_llseek,
184         .write          = watchdog_write,
185         .unlocked_ioctl = watchdog_ioctl,
186         .open           = watchdog_open,
187         .release        = watchdog_release,
188 };
189
190 static struct miscdevice watchdog_miscdev = {
191         .minor          = WATCHDOG_MINOR,
192         .name           = "watchdog",
193         .fops           = &watchdog_fops,
194 };
195
196 static int __init footbridge_watchdog_init(void)
197 {
198         int retval;
199
200         if (machine_is_netwinder())
201                 return -ENODEV;
202
203         retval = misc_register(&watchdog_miscdev);
204         if (retval < 0)
205                 return retval;
206
207         printk(KERN_INFO
208                 "Footbridge Watchdog Timer: 0.01, timer margin: %d sec\n",
209                                                                 soft_margin);
210
211         if (machine_is_cats())
212                 printk(KERN_WARNING
213                   "Warning: Watchdog reset may not work on this machine.\n");
214         return 0;
215 }
216
217 static void __exit footbridge_watchdog_exit(void)
218 {
219         misc_deregister(&watchdog_miscdev);
220 }
221
222 MODULE_AUTHOR("Phil Blundell <pb@nexus.co.uk>");
223 MODULE_DESCRIPTION("Footbridge watchdog driver");
224 MODULE_LICENSE("GPL");
225 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
226
227 module_param(soft_margin, int, 0);
228 MODULE_PARM_DESC(soft_margin, "Watchdog timeout in seconds");
229
230 module_init(footbridge_watchdog_init);
231 module_exit(footbridge_watchdog_exit);