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
30 #include <asm/irq.h>
31 #include <asm/uaccess.h>
32 #include <asm/hardware.h>
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
119 watchdog_write(struct file *file, const char *data, 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 struct watchdog_info ident = {
131 .options = WDIOF_SETTIMEOUT,
132 .identity = "Footbridge Watchdog",
133 };
134
135 static int
136 watchdog_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
137 unsigned long arg)
138 {
139 unsigned int new_margin;
140 int ret = -ENOTTY;
141
142 switch(cmd) {
143 case WDIOC_GETSUPPORT:
144 ret = 0;
145 if (copy_to_user((void *)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 .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("Footbridge Watchdog Timer: 0.01, timer margin: %d sec\n",
208 soft_margin);
209
210 if (machine_is_cats())
211 printk("Warning: Watchdog reset may not work on this machine.\n");
212 return 0;
213 }
214
215 static void __exit footbridge_watchdog_exit(void)
216 {
217 misc_deregister(&watchdog_miscdev);
218 }
219
220 MODULE_AUTHOR("Phil Blundell <pb@nexus.co.uk>");
221 MODULE_DESCRIPTION("Footbridge watchdog driver");
222 MODULE_LICENSE("GPL");
223 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
224
225 module_param(soft_margin, int, 0);
226 MODULE_PARM_DESC(soft_margin,"Watchdog timeout in seconds");
227
228 module_init(footbridge_watchdog_init);
229 module_exit(footbridge_watchdog_exit);
230
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