Merge remote-tracking branch 'stable/linux-5.15.y' into rpi-5.15.y
[platform/kernel/linux-rpi.git] / drivers / watchdog / wdt285.c
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  */
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  */
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  */
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  */
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
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
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                 fallthrough;
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         .compat_ioctl   = compat_ptr_ioctl,
185         .open           = watchdog_open,
186         .release        = watchdog_release,
187 };
188
189 static struct miscdevice watchdog_miscdev = {
190         .minor          = WATCHDOG_MINOR,
191         .name           = "watchdog",
192         .fops           = &watchdog_fops,
193 };
194
195 static int __init footbridge_watchdog_init(void)
196 {
197         int retval;
198
199         if (machine_is_netwinder())
200                 return -ENODEV;
201
202         retval = misc_register(&watchdog_miscdev);
203         if (retval < 0)
204                 return retval;
205
206         pr_info("Footbridge Watchdog Timer: 0.01, timer margin: %d sec\n",
207                 soft_margin);
208
209         if (machine_is_cats())
210                 pr_warn("Warning: Watchdog reset may not work on this machine\n");
211         return 0;
212 }
213
214 static void __exit footbridge_watchdog_exit(void)
215 {
216         misc_deregister(&watchdog_miscdev);
217 }
218
219 MODULE_AUTHOR("Phil Blundell <pb@nexus.co.uk>");
220 MODULE_DESCRIPTION("Footbridge watchdog driver");
221 MODULE_LICENSE("GPL");
222
223 module_param(soft_margin, int, 0);
224 MODULE_PARM_DESC(soft_margin, "Watchdog timeout in seconds");
225
226 module_init(footbridge_watchdog_init);
227 module_exit(footbridge_watchdog_exit);