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 #include <linux/module.h>
20 #include <linux/moduleparam.h>
21 #include <linux/types.h>
22 #include <linux/kernel.h>
23 #include <linux/fs.h>
24 #include <linux/mm.h>
25 #include <linux/miscdevice.h>
26 #include <linux/watchdog.h>
27 #include <linux/reboot.h>
28 #include <linux/init.h>
29 #include <linux/interrupt.h>
30 #include <linux/uaccess.h>
31 #include <linux/irq.h>
32 #include <mach/hardware.h>
33
34 #include <asm/mach-types.h>
35 #include <asm/hardware/dec21285.h>
36
37 /*
38 * Define this to stop the watchdog actually rebooting the machine.
39 */
40 #undef ONLY_TESTING
41
42 static unsigned int soft_margin = 60; /* in seconds */
43 static unsigned int reload;
44 static unsigned long timer_alive;
45
46 #ifdef ONLY_TESTING
47 /*
48 * If the timer expires..
49 */
50 static void watchdog_fire(int irq, void *dev_id)
51 {
52 printk(KERN_CRIT "Watchdog: Would Reboot.\n");
53 *CSR_TIMER4_CNTL = 0;
54 *CSR_TIMER4_CLR = 0;
55 }
56 #endif
57
58 /*
59 * Refresh the timer.
60 */
61 static void watchdog_ping(void)
62 {
63 *CSR_TIMER4_LOAD = reload;
64 }
65
66 /*
67 * Allow only one person to hold it open
68 */
69 static int watchdog_open(struct inode *inode, struct file *file)
70 {
71 int ret;
72
73 if (*CSR_SA110_CNTL & (1 << 13))
74 return -EBUSY;
75
76 if (test_and_set_bit(1, &timer_alive))
77 return -EBUSY;
78
79 reload = soft_margin * (mem_fclk_21285 / 256);
80
81 *CSR_TIMER4_CLR = 0;
82 watchdog_ping();
83 *CSR_TIMER4_CNTL = TIMER_CNTL_ENABLE | TIMER_CNTL_AUTORELOAD
84 | TIMER_CNTL_DIV256;
85
86 #ifdef ONLY_TESTING
87 ret = request_irq(IRQ_TIMER4, watchdog_fire, 0, "watchdog", NULL);
88 if (ret) {
89 *CSR_TIMER4_CNTL = 0;
90 clear_bit(1, &timer_alive);
91 }
92 #else
93 /*
94 * Setting this bit is irreversible; once enabled, there is
95 * no way to disable the watchdog.
96 */
97 *CSR_SA110_CNTL |= 1 << 13;
98
99 ret = 0;
100 #endif
101 nonseekable_open(inode, file);
102 return ret;
103 }
104
105 /*
106 * Shut off the timer.
107 * Note: if we really have enabled the watchdog, there
108 * is no way to turn off.
109 */
110 static int watchdog_release(struct inode *inode, struct file *file)
111 {
112 #ifdef ONLY_TESTING
113 free_irq(IRQ_TIMER4, NULL);
114 clear_bit(1, &timer_alive);
115 #endif
116 return 0;
117 }
118
119 static ssize_t watchdog_write(struct file *file, const char __user *data,
120 size_t len, loff_t *ppos)
121 {
122 /*
123 * Refresh the timer.
124 */
125 if (len)
126 watchdog_ping();
127
128 return len;
129 }
130
131 static const struct watchdog_info ident = {
132 .options = WDIOF_SETTIMEOUT,
133 .identity = "Footbridge Watchdog",
134 };
135
136 static long watchdog_ioctl(struct file *file, unsigned int cmd,
137 unsigned long arg)
138 {
139 unsigned int new_margin;
140 int __user *int_arg = (int __user *)arg;
141 int ret = -ENOTTY;
142
143 switch (cmd) {
144 case WDIOC_GETSUPPORT:
145 ret = 0;
146 if (copy_to_user((void __user *)arg, &ident, sizeof(ident)))
147 ret = -EFAULT;
148 break;
149
150 case WDIOC_GETSTATUS:
151 case WDIOC_GETBOOTSTATUS:
152 ret = put_user(0, int_arg);
153 break;
154
155 case WDIOC_KEEPALIVE:
156 watchdog_ping();
157 ret = 0;
158 break;
159
160 case WDIOC_SETTIMEOUT:
161 ret = get_user(new_margin, int_arg);
162 if (ret)
163 break;
164
165 /* Arbitrary, can't find the card's limits */
166 if (new_margin < 0 || new_margin > 60) {
167 ret = -EINVAL;
168 break;
169 }
170
171 soft_margin = new_margin;
172 reload = soft_margin * (mem_fclk_21285 / 256);
173 watchdog_ping();
174 /* Fall */
175 case WDIOC_GETTIMEOUT:
176 ret = put_user(soft_margin, int_arg);
177 break;
178 }
179 return ret;
180 }
181
182 static const struct file_operations watchdog_fops = {
183 .owner = THIS_MODULE,
184 .llseek = no_llseek,
185 .write = watchdog_write,
186 .unlocked_ioctl = watchdog_ioctl,
187 .open = watchdog_open,
188 .release = watchdog_release,
189 };
190
191 static struct miscdevice watchdog_miscdev = {
192 .minor = WATCHDOG_MINOR,
193 .name = "watchdog",
194 .fops = &watchdog_fops,
195 };
196
197 static int __init footbridge_watchdog_init(void)
198 {
199 int retval;
200
201 if (machine_is_netwinder())
202 return -ENODEV;
203
204 retval = misc_register(&watchdog_miscdev);
205 if (retval < 0)
206 return retval;
207
208 printk(KERN_INFO
209 "Footbridge Watchdog Timer: 0.01, timer margin: %d sec\n",
210 soft_margin);
211
212 if (machine_is_cats())
213 printk(KERN_WARNING
214 "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);
233
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