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