1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Intel 21285 watchdog driver
4 * Copyright (c) Phil Blundell <pb@nexus.co.uk>, 1998
5 *
6 * based on
7 *
8 * SoftDog 0.05: A Software Watchdog Device
9 *
10 * (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
11 * All Rights Reserved.
12 */
13
14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16 #include <linux/module.h>
17 #include <linux/moduleparam.h>
18 #include <linux/types.h>
19 #include <linux/kernel.h>
20 #include <linux/fs.h>
21 #include <linux/mm.h>
22 #include <linux/miscdevice.h>
23 #include <linux/watchdog.h>
24 #include <linux/reboot.h>
25 #include <linux/init.h>
26 #include <linux/interrupt.h>
27 #include <linux/uaccess.h>
28 #include <linux/irq.h>
29 #include <mach/hardware.h>
30
31 #include <asm/mach-types.h>
32 #include <asm/system_info.h>
33 #include <asm/hardware/dec21285.h>
34
35 /*
36 * Define this to stop the watchdog actually rebooting the machine.
37 */
38 #undef ONLY_TESTING
39
40 static unsigned int soft_margin = 60; /* in seconds */
41 static unsigned int reload;
42 static unsigned long timer_alive;
43
44 #ifdef ONLY_TESTING
45 /*
46 * If the timer expires..
47 */
watchdog_fire(int irq,void * dev_id)48 static void watchdog_fire(int irq, void *dev_id)
49 {
50 pr_crit("Would Reboot\n");
51 *CSR_TIMER4_CNTL = 0;
52 *CSR_TIMER4_CLR = 0;
53 }
54 #endif
55
56 /*
57 * Refresh the timer.
58 */
watchdog_ping(void)59 static void watchdog_ping(void)
60 {
61 *CSR_TIMER4_LOAD = reload;
62 }
63
64 /*
65 * Allow only one person to hold it open
66 */
watchdog_open(struct inode * inode,struct file * file)67 static int watchdog_open(struct inode *inode, struct file *file)
68 {
69 int ret;
70
71 if (*CSR_SA110_CNTL & (1 << 13))
72 return -EBUSY;
73
74 if (test_and_set_bit(1, &timer_alive))
75 return -EBUSY;
76
77 reload = soft_margin * (mem_fclk_21285 / 256);
78
79 *CSR_TIMER4_CLR = 0;
80 watchdog_ping();
81 *CSR_TIMER4_CNTL = TIMER_CNTL_ENABLE | TIMER_CNTL_AUTORELOAD
82 | TIMER_CNTL_DIV256;
83
84 #ifdef ONLY_TESTING
85 ret = request_irq(IRQ_TIMER4, watchdog_fire, 0, "watchdog", NULL);
86 if (ret) {
87 *CSR_TIMER4_CNTL = 0;
88 clear_bit(1, &timer_alive);
89 }
90 #else
91 /*
92 * Setting this bit is irreversible; once enabled, there is
93 * no way to disable the watchdog.
94 */
95 *CSR_SA110_CNTL |= 1 << 13;
96
97 ret = 0;
98 #endif
99 stream_open(inode, file);
100 return ret;
101 }
102
103 /*
104 * Shut off the timer.
105 * Note: if we really have enabled the watchdog, there
106 * is no way to turn off.
107 */
watchdog_release(struct inode * inode,struct file * file)108 static int watchdog_release(struct inode *inode, struct file *file)
109 {
110 #ifdef ONLY_TESTING
111 free_irq(IRQ_TIMER4, NULL);
112 clear_bit(1, &timer_alive);
113 #endif
114 return 0;
115 }
116
watchdog_write(struct file * file,const char __user * data,size_t len,loff_t * ppos)117 static ssize_t watchdog_write(struct file *file, const char __user *data,
118 size_t len, loff_t *ppos)
119 {
120 /*
121 * Refresh the timer.
122 */
123 if (len)
124 watchdog_ping();
125
126 return len;
127 }
128
129 static const struct watchdog_info ident = {
130 .options = WDIOF_SETTIMEOUT,
131 .identity = "Footbridge Watchdog",
132 };
133
watchdog_ioctl(struct file * file,unsigned int cmd,unsigned long arg)134 static long watchdog_ioctl(struct file *file, unsigned int cmd,
135 unsigned long arg)
136 {
137 int __user *int_arg = (int __user *)arg;
138 int new_margin, ret = -ENOTTY;
139
140 switch (cmd) {
141 case WDIOC_GETSUPPORT:
142 ret = 0;
143 if (copy_to_user((void __user *)arg, &ident, sizeof(ident)))
144 ret = -EFAULT;
145 break;
146
147 case WDIOC_GETSTATUS:
148 case WDIOC_GETBOOTSTATUS:
149 ret = put_user(0, int_arg);
150 break;
151
152 case WDIOC_KEEPALIVE:
153 watchdog_ping();
154 ret = 0;
155 break;
156
157 case WDIOC_SETTIMEOUT:
158 ret = get_user(new_margin, int_arg);
159 if (ret)
160 break;
161
162 /* Arbitrary, can't find the card's limits */
163 if (new_margin < 0 || new_margin > 60) {
164 ret = -EINVAL;
165 break;
166 }
167
168 soft_margin = new_margin;
169 reload = soft_margin * (mem_fclk_21285 / 256);
170 watchdog_ping();
171 /* Fall through */
172 case WDIOC_GETTIMEOUT:
173 ret = put_user(soft_margin, int_arg);
174 break;
175 }
176 return ret;
177 }
178
179 static const struct file_operations watchdog_fops = {
180 .owner = THIS_MODULE,
181 .llseek = no_llseek,
182 .write = watchdog_write,
183 .unlocked_ioctl = watchdog_ioctl,
184 .open = watchdog_open,
185 .release = watchdog_release,
186 };
187
188 static struct miscdevice watchdog_miscdev = {
189 .minor = WATCHDOG_MINOR,
190 .name = "watchdog",
191 .fops = &watchdog_fops,
192 };
193
footbridge_watchdog_init(void)194 static int __init footbridge_watchdog_init(void)
195 {
196 int retval;
197
198 if (machine_is_netwinder())
199 return -ENODEV;
200
201 retval = misc_register(&watchdog_miscdev);
202 if (retval < 0)
203 return retval;
204
205 pr_info("Footbridge Watchdog Timer: 0.01, timer margin: %d sec\n",
206 soft_margin);
207
208 if (machine_is_cats())
209 pr_warn("Warning: Watchdog reset may not work on this machine\n");
210 return 0;
211 }
212
footbridge_watchdog_exit(void)213 static void __exit footbridge_watchdog_exit(void)
214 {
215 misc_deregister(&watchdog_miscdev);
216 }
217
218 MODULE_AUTHOR("Phil Blundell <pb@nexus.co.uk>");
219 MODULE_DESCRIPTION("Footbridge watchdog driver");
220 MODULE_LICENSE("GPL");
221
222 module_param(soft_margin, int, 0);
223 MODULE_PARM_DESC(soft_margin, "Watchdog timeout in seconds");
224
225 module_init(footbridge_watchdog_init);
226 module_exit(footbridge_watchdog_exit);
227
