ebbb183be6182f3083a5da4ce2e75731ea1bc2ec
[sfrench/cifs-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/system_info.h>
38 #include <asm/hardware/dec21285.h>
39
40 /*
41  * Define this to stop the watchdog actually rebooting the machine.
42  */
43 #undef ONLY_TESTING
44
45 static unsigned int soft_margin = 60;           /* in seconds */
46 static unsigned int reload;
47 static unsigned long timer_alive;
48
49 #ifdef ONLY_TESTING
50 /*
51  *      If the timer expires..
52  */
53 static void watchdog_fire(int irq, void *dev_id)
54 {
55         pr_crit("Would Reboot\n");
56         *CSR_TIMER4_CNTL = 0;
57         *CSR_TIMER4_CLR = 0;
58 }
59 #endif
60
61 /*
62  *      Refresh the timer.
63  */
64 static void watchdog_ping(void)
65 {
66         *CSR_TIMER4_LOAD = reload;
67 }
68
69 /*
70  *      Allow only one person to hold it open
71  */
72 static int watchdog_open(struct inode *inode, struct file *file)
73 {
74         int ret;
75
76         if (*CSR_SA110_CNTL & (1 << 13))
77                 return -EBUSY;
78
79         if (test_and_set_bit(1, &timer_alive))
80                 return -EBUSY;
81
82         reload = soft_margin * (mem_fclk_21285 / 256);
83
84         *CSR_TIMER4_CLR = 0;
85         watchdog_ping();
86         *CSR_TIMER4_CNTL = TIMER_CNTL_ENABLE | TIMER_CNTL_AUTORELOAD
87                 | TIMER_CNTL_DIV256;
88
89 #ifdef ONLY_TESTING
90         ret = request_irq(IRQ_TIMER4, watchdog_fire, 0, "watchdog", NULL);
91         if (ret) {
92                 *CSR_TIMER4_CNTL = 0;
93                 clear_bit(1, &timer_alive);
94         }
95 #else
96         /*
97          * Setting this bit is irreversible; once enabled, there is
98          * no way to disable the watchdog.
99          */
100         *CSR_SA110_CNTL |= 1 << 13;
101
102         ret = 0;
103 #endif
104         nonseekable_open(inode, file);
105         return ret;
106 }
107
108 /*
109  *      Shut off the timer.
110  *      Note: if we really have enabled the watchdog, there
111  *      is no way to turn off.
112  */
113 static int watchdog_release(struct inode *inode, struct file *file)
114 {
115 #ifdef ONLY_TESTING
116         free_irq(IRQ_TIMER4, NULL);
117         clear_bit(1, &timer_alive);
118 #endif
119         return 0;
120 }
121
122 static ssize_t watchdog_write(struct file *file, const char __user *data,
123                               size_t len, loff_t *ppos)
124 {
125         /*
126          *      Refresh the timer.
127          */
128         if (len)
129                 watchdog_ping();
130
131         return len;
132 }
133
134 static const struct watchdog_info ident = {
135         .options        = WDIOF_SETTIMEOUT,
136         .identity       = "Footbridge Watchdog",
137 };
138
139 static long watchdog_ioctl(struct file *file, unsigned int cmd,
140                            unsigned long arg)
141 {
142         int __user *int_arg = (int __user *)arg;
143         int new_margin, 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
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);