1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * sma cpu5 watchdog driver
4 *
5 * Copyright (C) 2003 Heiko Ronsdorf <hero@ihg.uni-duisburg.de>
6 */
7
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10#include <linux/module.h>
11#include <linux/moduleparam.h>
12#include <linux/types.h>
13#include <linux/errno.h>
14#include <linux/miscdevice.h>
15#include <linux/fs.h>
16#include <linux/ioport.h>
17#include <linux/timer.h>
18#include <linux/completion.h>
19#include <linux/jiffies.h>
20#include <linux/io.h>
21#include <linux/uaccess.h>
22#include <linux/watchdog.h>
23
24/* adjustable parameters */
25
26static int verbose;
27static int port = 0x91;
28static int ticks = 10000;
29static DEFINE_SPINLOCK(cpu5wdt_lock);
30
31#define PFX			"cpu5wdt: "
32
33#define CPU5WDT_EXTENT          0x0A
34
35#define CPU5WDT_STATUS_REG      0x00
36#define CPU5WDT_TIME_A_REG      0x02
37#define CPU5WDT_TIME_B_REG      0x03
38#define CPU5WDT_MODE_REG        0x04
39#define CPU5WDT_TRIGGER_REG     0x07
40#define CPU5WDT_ENABLE_REG      0x08
41#define CPU5WDT_RESET_REG       0x09
42
43#define CPU5WDT_INTERVAL	(HZ/10+1)
44
45/* some device data */
46
47static struct {
48	struct completion stop;
49	int running;
50	struct timer_list timer;
51	int queue;
52	int default_ticks;
53	unsigned long inuse;
54} cpu5wdt_device;
55
56/* generic helper functions */
57
58static void cpu5wdt_trigger(struct timer_list *unused)
59{
60	if (verbose > 2)
61		pr_debug("trigger at %i ticks\n", ticks);
62
63	if (cpu5wdt_device.running)
64		ticks--;
65
66	spin_lock(&cpu5wdt_lock);
67	/* keep watchdog alive */
68	outb(1, port + CPU5WDT_TRIGGER_REG);
69
70	/* requeue?? */
71	if (cpu5wdt_device.queue && ticks)
72		mod_timer(&cpu5wdt_device.timer, jiffies + CPU5WDT_INTERVAL);
73	else {
74		/* ticks doesn't matter anyway */
75		complete(&cpu5wdt_device.stop);
76	}
77	spin_unlock(&cpu5wdt_lock);
78
79}
80
81static void cpu5wdt_reset(void)
82{
83	ticks = cpu5wdt_device.default_ticks;
84
85	if (verbose)
86		pr_debug("reset (%i ticks)\n", (int) ticks);
87
88}
89
90static void cpu5wdt_start(void)
91{
92	unsigned long flags;
93
94	spin_lock_irqsave(&cpu5wdt_lock, flags);
95	if (!cpu5wdt_device.queue) {
96		cpu5wdt_device.queue = 1;
97		outb(0, port + CPU5WDT_TIME_A_REG);
98		outb(0, port + CPU5WDT_TIME_B_REG);
99		outb(1, port + CPU5WDT_MODE_REG);
100		outb(0, port + CPU5WDT_RESET_REG);
101		outb(0, port + CPU5WDT_ENABLE_REG);
102		mod_timer(&cpu5wdt_device.timer, jiffies + CPU5WDT_INTERVAL);
103	}
104	/* if process dies, counter is not decremented */
105	cpu5wdt_device.running++;
106	spin_unlock_irqrestore(&cpu5wdt_lock, flags);
107}
108
109static int cpu5wdt_stop(void)
110{
111	unsigned long flags;
112
113	spin_lock_irqsave(&cpu5wdt_lock, flags);
114	if (cpu5wdt_device.running)
115		cpu5wdt_device.running = 0;
116	ticks = cpu5wdt_device.default_ticks;
117	spin_unlock_irqrestore(&cpu5wdt_lock, flags);
118	if (verbose)
119		pr_crit("stop not possible\n");
120	return -EIO;
121}
122
123/* filesystem operations */
124
125static int cpu5wdt_open(struct inode *inode, struct file *file)
126{
127	if (test_and_set_bit(0, &cpu5wdt_device.inuse))
128		return -EBUSY;
129	return stream_open(inode, file);
130}
131
132static int cpu5wdt_release(struct inode *inode, struct file *file)
133{
134	clear_bit(0, &cpu5wdt_device.inuse);
135	return 0;
136}
137
138static long cpu5wdt_ioctl(struct file *file, unsigned int cmd,
139						unsigned long arg)
140{
141	void __user *argp = (void __user *)arg;
142	int __user *p = argp;
143	unsigned int value;
144	static const struct watchdog_info ident = {
145		.options = WDIOF_CARDRESET,
146		.identity = "CPU5 WDT",
147	};
148
149	switch (cmd) {
150	case WDIOC_GETSUPPORT:
151		if (copy_to_user(argp, &ident, sizeof(ident)))
152			return -EFAULT;
153		break;
154	case WDIOC_GETSTATUS:
155		value = inb(port + CPU5WDT_STATUS_REG);
156		value = (value >> 2) & 1;
157		return put_user(value, p);
158	case WDIOC_GETBOOTSTATUS:
159		return put_user(0, p);
160	case WDIOC_SETOPTIONS:
161		if (get_user(value, p))
162			return -EFAULT;
163		if (value & WDIOS_ENABLECARD)
164			cpu5wdt_start();
165		if (value & WDIOS_DISABLECARD)
166			cpu5wdt_stop();
167		break;
168	case WDIOC_KEEPALIVE:
169		cpu5wdt_reset();
170		break;
171	default:
172		return -ENOTTY;
173	}
174	return 0;
175}
176
177static ssize_t cpu5wdt_write(struct file *file, const char __user *buf,
178						size_t count, loff_t *ppos)
179{
180	if (!count)
181		return -EIO;
182	cpu5wdt_reset();
183	return count;
184}
185
186static const struct file_operations cpu5wdt_fops = {
187	.owner		= THIS_MODULE,
188	.llseek		= no_llseek,
189	.unlocked_ioctl	= cpu5wdt_ioctl,
190	.compat_ioctl	= compat_ptr_ioctl,
191	.open		= cpu5wdt_open,
192	.write		= cpu5wdt_write,
193	.release	= cpu5wdt_release,
194};
195
196static struct miscdevice cpu5wdt_misc = {
197	.minor	= WATCHDOG_MINOR,
198	.name	= "watchdog",
199	.fops	= &cpu5wdt_fops,
200};
201
202/* init/exit function */
203
204static int cpu5wdt_init(void)
205{
206	unsigned int val;
207	int err;
208
209	if (verbose)
210		pr_debug("port=0x%x, verbose=%i\n", port, verbose);
211
212	init_completion(&cpu5wdt_device.stop);
213	cpu5wdt_device.queue = 0;
214	timer_setup(&cpu5wdt_device.timer, cpu5wdt_trigger, 0);
215	cpu5wdt_device.default_ticks = ticks;
216
217	if (!request_region(port, CPU5WDT_EXTENT, PFX)) {
218		pr_err("request_region failed\n");
219		err = -EBUSY;
220		goto no_port;
221	}
222
223	/* watchdog reboot? */
224	val = inb(port + CPU5WDT_STATUS_REG);
225	val = (val >> 2) & 1;
226	if (!val)
227		pr_info("sorry, was my fault\n");
228
229	err = misc_register(&cpu5wdt_misc);
230	if (err < 0) {
231		pr_err("misc_register failed\n");
232		goto no_misc;
233	}
234
235
236	pr_info("init success\n");
237	return 0;
238
239no_misc:
240	release_region(port, CPU5WDT_EXTENT);
241no_port:
242	return err;
243}
244
245static int cpu5wdt_init_module(void)
246{
247	return cpu5wdt_init();
248}
249
250static void cpu5wdt_exit(void)
251{
252	if (cpu5wdt_device.queue) {
253		cpu5wdt_device.queue = 0;
254		wait_for_completion(&cpu5wdt_device.stop);
255		del_timer(&cpu5wdt_device.timer);
256	}
257
258	misc_deregister(&cpu5wdt_misc);
259
260	release_region(port, CPU5WDT_EXTENT);
261
262}
263
264static void cpu5wdt_exit_module(void)
265{
266	cpu5wdt_exit();
267}
268
269/* module entry points */
270
271module_init(cpu5wdt_init_module);
272module_exit(cpu5wdt_exit_module);
273
274MODULE_AUTHOR("Heiko Ronsdorf <hero@ihg.uni-duisburg.de>");
275MODULE_DESCRIPTION("sma cpu5 watchdog driver");
276MODULE_LICENSE("GPL");
277
278module_param_hw(port, int, ioport, 0);
279MODULE_PARM_DESC(port, "base address of watchdog card, default is 0x91");
280
281module_param(verbose, int, 0);
282MODULE_PARM_DESC(verbose, "be verbose, default is 0 (no)");
283
284module_param(ticks, int, 0);
285MODULE_PARM_DESC(ticks, "count down ticks, default is 10000");
286