1/*
2 * Watchdog driver for Kendin/Micrel KS8695.
3 *
4 * (C) 2007 Andrew Victor
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11#include <linux/errno.h>
12#include <linux/fs.h>
13#include <linux/init.h>
14#include <linux/kernel.h>
15#include <linux/miscdevice.h>
16#include <linux/module.h>
17#include <linux/moduleparam.h>
18#include <linux/platform_device.h>
19#include <linux/types.h>
20#include <linux/watchdog.h>
21#include <asm/bitops.h>
22#include <asm/io.h>
23#include <asm/uaccess.h>
24#include <asm/arch/regs-timer.h>
25
26
27#define WDT_DEFAULT_TIME	5	/* seconds */
28#define WDT_MAX_TIME		171	/* seconds */
29
30static int wdt_time = WDT_DEFAULT_TIME;
31static int nowayout = WATCHDOG_NOWAYOUT;
32
33module_param(wdt_time, int, 0);
34MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="__MODULE_STRING(WDT_DEFAULT_TIME) ")");
35
36#ifdef CONFIG_WATCHDOG_NOWAYOUT
37module_param(nowayout, int, 0);
38MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
39#endif
40
41
42static unsigned long ks8695wdt_busy;
43
44/* ......................................................................... */
45
46/*
47 * Disable the watchdog.
48 */
49static void inline ks8695_wdt_stop(void)
50{
51	unsigned long tmcon;
52
53	/* disable timer0 */
54	tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
55	__raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
56}
57
58/*
59 * Enable and reset the watchdog.
60 */
61static void inline ks8695_wdt_start(void)
62{
63	unsigned long tmcon;
64	unsigned long tval = wdt_time * CLOCK_TICK_RATE;
65
66	/* disable timer0 */
67	tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
68	__raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
69
70	/* program timer0 */
71	__raw_writel(tval | T0TC_WATCHDOG, KS8695_TMR_VA + KS8695_T0TC);
72
73	/* re-enable timer0 */
74	tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
75	__raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
76}
77
78/*
79 * Reload the watchdog timer.  (ie, pat the watchdog)
80 */
81static void inline ks8695_wdt_reload(void)
82{
83	unsigned long tmcon;
84
85	/* disable, then re-enable timer0 */
86	tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
87	__raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
88	__raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
89}
90
91/*
92 * Change the watchdog time interval.
93 */
94static int ks8695_wdt_settimeout(int new_time)
95{
96	/*
97	 * All counting occurs at SLOW_CLOCK / 128 = 0.256 Hz
98	 *
99	 * Since WDV is a 16-bit counter, the maximum period is
100	 * 65536 / 0.256 = 256 seconds.
101	 */
102	if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
103		return -EINVAL;
104
105	/* Set new watchdog time. It will be used when ks8695_wdt_start() is called. */
106	wdt_time = new_time;
107	return 0;
108}
109
110/* ......................................................................... */
111
112/*
113 * Watchdog device is opened, and watchdog starts running.
114 */
115static int ks8695_wdt_open(struct inode *inode, struct file *file)
116{
117	if (test_and_set_bit(0, &ks8695wdt_busy))
118		return -EBUSY;
119
120	ks8695_wdt_start();
121	return nonseekable_open(inode, file);
122}
123
124/*
125 * Close the watchdog device.
126 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
127 *  disabled.
128 */
129static int ks8695_wdt_close(struct inode *inode, struct file *file)
130{
131	if (!nowayout)
132		ks8695_wdt_stop();	/* Disable the watchdog when file is closed */
133
134	clear_bit(0, &ks8695wdt_busy);
135	return 0;
136}
137
138static struct watchdog_info ks8695_wdt_info = {
139	.identity	= "ks8695 watchdog",
140	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
141};
142
143/*
144 * Handle commands from user-space.
145 */
146static int ks8695_wdt_ioctl(struct inode *inode, struct file *file,
147		unsigned int cmd, unsigned long arg)
148{
149	void __user *argp = (void __user *)arg;
150	int __user *p = argp;
151	int new_value;
152
153	switch(cmd) {
154		case WDIOC_KEEPALIVE:
155			ks8695_wdt_reload();	/* pat the watchdog */
156			return 0;
157
158		case WDIOC_GETSUPPORT:
159			return copy_to_user(argp, &ks8695_wdt_info, sizeof(ks8695_wdt_info)) ? -EFAULT : 0;
160
161		case WDIOC_SETTIMEOUT:
162			if (get_user(new_value, p))
163				return -EFAULT;
164
165			if (ks8695_wdt_settimeout(new_value))
166				return -EINVAL;
167
168			/* Enable new time value */
169			ks8695_wdt_start();
170
171			/* Return current value */
172			return put_user(wdt_time, p);
173
174		case WDIOC_GETTIMEOUT:
175			return put_user(wdt_time, p);
176
177		case WDIOC_GETSTATUS:
178		case WDIOC_GETBOOTSTATUS:
179			return put_user(0, p);
180
181		case WDIOC_SETOPTIONS:
182			if (get_user(new_value, p))
183				return -EFAULT;
184
185			if (new_value & WDIOS_DISABLECARD)
186				ks8695_wdt_stop();
187			if (new_value & WDIOS_ENABLECARD)
188				ks8695_wdt_start();
189			return 0;
190
191		default:
192			return -ENOTTY;
193	}
194}
195
196/*
197 * Pat the watchdog whenever device is written to.
198 */
199static ssize_t ks8695_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
200{
201	ks8695_wdt_reload();		/* pat the watchdog */
202	return len;
203}
204
205/* ......................................................................... */
206
207static const struct file_operations ks8695wdt_fops = {
208	.owner		= THIS_MODULE,
209	.llseek		= no_llseek,
210	.ioctl		= ks8695_wdt_ioctl,
211	.open		= ks8695_wdt_open,
212	.release	= ks8695_wdt_close,
213	.write		= ks8695_wdt_write,
214};
215
216static struct miscdevice ks8695wdt_miscdev = {
217	.minor		= WATCHDOG_MINOR,
218	.name		= "watchdog",
219	.fops		= &ks8695wdt_fops,
220};
221
222static int __init ks8695wdt_probe(struct platform_device *pdev)
223{
224	int res;
225
226	if (ks8695wdt_miscdev.parent)
227		return -EBUSY;
228	ks8695wdt_miscdev.parent = &pdev->dev;
229
230	res = misc_register(&ks8695wdt_miscdev);
231	if (res)
232		return res;
233
234	printk("KS8695 Watchdog Timer enabled (%d seconds%s)\n", wdt_time, nowayout ? ", nowayout" : "");
235	return 0;
236}
237
238static int __exit ks8695wdt_remove(struct platform_device *pdev)
239{
240	int res;
241
242	res = misc_deregister(&ks8695wdt_miscdev);
243	if (!res)
244		ks8695wdt_miscdev.parent = NULL;
245
246	return res;
247}
248
249static void ks8695wdt_shutdown(struct platform_device *pdev)
250{
251	ks8695_wdt_stop();
252}
253
254#ifdef CONFIG_PM
255
256static int ks8695wdt_suspend(struct platform_device *pdev, pm_message_t message)
257{
258	ks8695_wdt_stop();
259	return 0;
260}
261
262static int ks8695wdt_resume(struct platform_device *pdev)
263{
264	if (ks8695wdt_busy)
265		ks8695_wdt_start();
266	return 0;
267}
268
269#else
270#define ks8695wdt_suspend NULL
271#define ks8695wdt_resume	NULL
272#endif
273
274static struct platform_driver ks8695wdt_driver = {
275	.probe		= ks8695wdt_probe,
276	.remove		= __exit_p(ks8695wdt_remove),
277	.shutdown	= ks8695wdt_shutdown,
278	.suspend	= ks8695wdt_suspend,
279	.resume		= ks8695wdt_resume,
280	.driver		= {
281		.name	= "ks8695_wdt",
282		.owner	= THIS_MODULE,
283	},
284};
285
286static int __init ks8695_wdt_init(void)
287{
288	/* Check that the heartbeat value is within range; if not reset to the default */
289	if (ks8695_wdt_settimeout(wdt_time)) {
290		ks8695_wdt_settimeout(WDT_DEFAULT_TIME);
291		pr_info("ks8695_wdt: wdt_time value must be 1 <= wdt_time <= %i, using %d\n", wdt_time, WDT_MAX_TIME);
292	}
293
294	return platform_driver_register(&ks8695wdt_driver);
295}
296
297static void __exit ks8695_wdt_exit(void)
298{
299	platform_driver_unregister(&ks8695wdt_driver);
300}
301
302module_init(ks8695_wdt_init);
303module_exit(ks8695_wdt_exit);
304
305MODULE_AUTHOR("Andrew Victor");
306MODULE_DESCRIPTION("Watchdog driver for KS8695");
307MODULE_LICENSE("GPL");
308MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
309