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
40static unsigned int soft_margin = 60;		/* in seconds */
41static unsigned int reload;
42static unsigned long timer_alive;
43
44#ifdef ONLY_TESTING
45/*
46 *	If the timer expires..
47 */
48static 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 */
59static void watchdog_ping(void)
60{
61	*CSR_TIMER4_LOAD = reload;
62}
63
64/*
65 *	Allow only one person to hold it open
66 */
67static 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 */
108static 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
117static 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
129static const struct watchdog_info ident = {
130	.options	= WDIOF_SETTIMEOUT,
131	.identity	= "Footbridge Watchdog",
132};
133
134static 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
179static 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
189static struct miscdevice watchdog_miscdev = {
190	.minor		= WATCHDOG_MINOR,
191	.name		= "watchdog",
192	.fops		= &watchdog_fops,
193};
194
195static 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
214static void __exit footbridge_watchdog_exit(void)
215{
216	misc_deregister(&watchdog_miscdev);
217}
218
219MODULE_AUTHOR("Phil Blundell <pb@nexus.co.uk>");
220MODULE_DESCRIPTION("Footbridge watchdog driver");
221MODULE_LICENSE("GPL");
222
223module_param(soft_margin, int, 0);
224MODULE_PARM_DESC(soft_margin, "Watchdog timeout in seconds");
225
226module_init(footbridge_watchdog_init);
227module_exit(footbridge_watchdog_exit);
228