tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
45static unsigned int soft_margin = 60; /* in seconds */
46static unsigned int reload;
47static unsigned long timer_alive;
48
49#ifdef ONLY_TESTING
50/*
51 * If the timer expires..
52 */
53static 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 */
64static void watchdog_ping(void)
65{
66 *CSR_TIMER4_LOAD = reload;
67}
68
69/*
70 * Allow only one person to hold it open
71 */
72static 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 */
113static 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
122static 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
134static const struct watchdog_info ident = {
135 .options = WDIOF_SETTIMEOUT,
136 .identity = "Footbridge Watchdog",
137};
138
139static long watchdog_ioctl(struct file *file, unsigned int cmd,
140 unsigned long arg)
141{
142 unsigned int new_margin;
143 int __user *int_arg = (int __user *)arg;
144 int ret = -ENOTTY;
145
146 switch (cmd) {
147 case WDIOC_GETSUPPORT:
148 ret = 0;
149 if (copy_to_user((void __user *)arg, &ident, sizeof(ident)))
150 ret = -EFAULT;
151 break;
152
153 case WDIOC_GETSTATUS:
154 case WDIOC_GETBOOTSTATUS:
155 ret = put_user(0, int_arg);
156 break;
157
158 case WDIOC_KEEPALIVE:
159 watchdog_ping();
160 ret = 0;
161 break;
162
163 case WDIOC_SETTIMEOUT:
164 ret = get_user(new_margin, int_arg);
165 if (ret)
166 break;
167
168 /* Arbitrary, can't find the card's limits */
169 if (new_margin < 0 || new_margin > 60) {
170 ret = -EINVAL;
171 break;
172 }
173
174 soft_margin = new_margin;
175 reload = soft_margin * (mem_fclk_21285 / 256);
176 watchdog_ping();
177 /* Fall */
178 case WDIOC_GETTIMEOUT:
179 ret = put_user(soft_margin, int_arg);
180 break;
181 }
182 return ret;
183}
184
185static const struct file_operations watchdog_fops = {
186 .owner = THIS_MODULE,
187 .llseek = no_llseek,
188 .write = watchdog_write,
189 .unlocked_ioctl = watchdog_ioctl,
190 .open = watchdog_open,
191 .release = watchdog_release,
192};
193
194static struct miscdevice watchdog_miscdev = {
195 .minor = WATCHDOG_MINOR,
196 .name = "watchdog",
197 .fops = &watchdog_fops,
198};
199
200static int __init footbridge_watchdog_init(void)
201{
202 int retval;
203
204 if (machine_is_netwinder())
205 return -ENODEV;
206
207 retval = misc_register(&watchdog_miscdev);
208 if (retval < 0)
209 return retval;
210
211 pr_info("Footbridge Watchdog Timer: 0.01, timer margin: %d sec\n",
212 soft_margin);
213
214 if (machine_is_cats())
215 pr_warn("Warning: Watchdog reset may not work on this machine\n");
216 return 0;
217}
218
219static void __exit footbridge_watchdog_exit(void)
220{
221 misc_deregister(&watchdog_miscdev);
222}
223
224MODULE_AUTHOR("Phil Blundell <pb@nexus.co.uk>");
225MODULE_DESCRIPTION("Footbridge watchdog driver");
226MODULE_LICENSE("GPL");
227MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
228
229module_param(soft_margin, int, 0);
230MODULE_PARM_DESC(soft_margin, "Watchdog timeout in seconds");
231
232module_init(footbridge_watchdog_init);
233module_exit(footbridge_watchdog_exit);