1/*
2 *	ADM5120_WDT 0.01: Infineon ADM5120 SoC watchdog driver
3 *	Copyright (c) Ondrej Zajicek <santiago@crfreenet.org>, 2007
4 *
5 *	based on
6 *
7 *	RC32434_WDT 0.01: IDT Interprise 79RC32434 watchdog driver
8 *
9 *	This program is free software; you can redistribute it and/or
10 *	modify it under the terms of the GNU General Public License
11 *	as published by the Free Software Foundation; either version
12 *	2 of the License, or (at your option) any later version.
13 *
14 */
15#include <linux/module.h>
16#include <linux/types.h>
17#include <linux/fs.h>
18#include <linux/miscdevice.h>
19#include <linux/watchdog.h>
20#include <linux/irq.h>
21
22#include <asm/bootinfo.h>
23
24#include <asm/mach-adm5120/adm5120_info.h>
25#include <asm/mach-adm5120/adm5120_defs.h>
26#include <asm/mach-adm5120/adm5120_switch.h>
27
28#define DEFAULT_TIMEOUT	15		/* (secs) Default is 15 seconds */
29#define MAX_TIMEOUT	327
30/* Max is 327 seconds, counter is 15-bit integer, step is 10 ms */
31
32#define NAME "adm5120_wdt"
33#define VERSION "0.1"
34
35static int expect_close;
36static int access;
37static unsigned int timeout = DEFAULT_TIMEOUT;
38
39static int nowayout = WATCHDOG_NOWAYOUT;
40module_param(nowayout, int, 0);
41MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
42MODULE_LICENSE("GPL");
43
44
45static inline void wdt_set_timeout(void)
46{
47	u32 val = (1 << 31) | (((timeout * 100) & 0x7FFF) << 16);
48	SW_WRITE_REG(SWITCH_REG_WDOG0, val);
49}
50
51/*
52   It looks like WDOG0-register-write don't modify counter,
53   but WDOG0-register-read resets counter.
54*/
55
56static inline void wdt_reset_counter(void)
57{
58	SW_READ_REG(SWITCH_REG_WDOG0);
59}
60
61static inline void wdt_disable(void)
62{
63	SW_WRITE_REG(SWITCH_REG_WDOG0, 0x7FFF0000);
64}
65
66
67
68static int wdt_open(struct inode *inode, struct file *file)
69{
70	/* Allow only one person to hold it open */
71	if (access)
72		return -EBUSY;
73
74	if (nowayout)
75		__module_get(THIS_MODULE);
76
77	/* Activate timer */
78	wdt_reset_counter();
79	wdt_set_timeout();
80	printk(KERN_INFO NAME ": enabling watchdog timer\n");
81	access = 1;
82	return 0;
83}
84
85static int wdt_release(struct inode *inode, struct file *file)
86{
87	/*
88	 * Shut off the timer.
89	 * Lock it in if it's a module and we set nowayout
90	 */
91	if (expect_close && (nowayout == 0)) {
92		wdt_disable();
93		printk(KERN_INFO NAME ": disabling watchdog timer\n");
94		module_put(THIS_MODULE);
95	} else
96		printk(KERN_CRIT NAME ": device closed unexpectedly.  WDT will not stop!\n");
97
98	access = 0;
99	return 0;
100}
101
102static ssize_t wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
103{
104	/* Refresh the timer. */
105	if (len) {
106		if (!nowayout) {
107			size_t i;
108
109			/* In case it was set long ago */
110			expect_close = 0;
111
112			for (i = 0; i != len; i++) {
113				char c;
114				if (get_user(c, data + i))
115					return -EFAULT;
116				if (c == 'V')
117					expect_close = 1;
118			}
119		}
120		wdt_reset_counter();
121		return len;
122	}
123	return 0;
124}
125
126static long wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
127{
128	int new_timeout;
129	static struct watchdog_info ident = {
130		.options =		WDIOF_SETTIMEOUT |
131					WDIOF_KEEPALIVEPING |
132					WDIOF_MAGICCLOSE,
133		.firmware_version =	0,
134		.identity =		"ADM5120_WDT Watchdog",
135	};
136	switch (cmd) {
137	default:
138		return -ENOTTY;
139	case WDIOC_GETSUPPORT:
140		if (copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident)))
141			return -EFAULT;
142		return 0;
143	case WDIOC_GETSTATUS:
144	case WDIOC_GETBOOTSTATUS:
145		return put_user(0, (int *)arg);
146	case WDIOC_KEEPALIVE:
147		wdt_reset_counter();
148		return 0;
149	case WDIOC_SETTIMEOUT:
150		if (get_user(new_timeout, (int *)arg))
151			return -EFAULT;
152		if (new_timeout < 1)
153			return -EINVAL;
154		if (new_timeout > MAX_TIMEOUT)
155			return -EINVAL;
156		timeout = new_timeout;
157		wdt_set_timeout();
158		/* Fall */
159	case WDIOC_GETTIMEOUT:
160		return put_user(timeout, (int *)arg);
161	}
162}
163
164static const struct file_operations wdt_fops = {
165	.owner		= THIS_MODULE,
166	.llseek		= no_llseek,
167	.write		= wdt_write,
168	.unlocked_ioctl	= wdt_ioctl,
169	.open		= wdt_open,
170	.release	= wdt_release,
171};
172
173static struct miscdevice wdt_miscdev = {
174	.minor		= WATCHDOG_MINOR,
175	.name		= "watchdog",
176	.fops		= &wdt_fops,
177};
178
179static char banner[] __initdata = KERN_INFO NAME ": Watchdog Timer version " VERSION "\n";
180
181static int __init watchdog_init(void)
182{
183	int ret;
184
185	ret = misc_register(&wdt_miscdev);
186
187	if (ret)
188		return ret;
189
190	wdt_disable();
191	printk(banner);
192
193	return 0;
194}
195
196static void __exit watchdog_exit(void)
197{
198	misc_deregister(&wdt_miscdev);
199}
200
201module_init(watchdog_init);
202module_exit(watchdog_exit);
203