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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13#include <linux/bitops.h>
14#include <linux/errno.h>
15#include <linux/fs.h>
16#include <linux/init.h>
17#include <linux/kernel.h>
18#include <linux/miscdevice.h>
19#include <linux/module.h>
20#include <linux/moduleparam.h>
21#include <linux/platform_device.h>
22#include <linux/types.h>
23#include <linux/watchdog.h>
24#include <linux/io.h>
25#include <linux/uaccess.h>
26#include <mach/hardware.h>
27
28#define KS8695_TMR_OFFSET	(0xF0000 + 0xE400)
29#define KS8695_TMR_VA		(KS8695_IO_VA + KS8695_TMR_OFFSET)
30
31/*
32 * Timer registers
33 */
34#define KS8695_TMCON		(0x00)		/* Timer Control Register */
35#define KS8695_T0TC		(0x08)		/* Timer 0 Timeout Count Register */
36#define TMCON_T0EN		(1 << 0)	/* Timer 0 Enable */
37
38/* Timer0 Timeout Counter Register */
39#define T0TC_WATCHDOG		(0xff)		/* Enable watchdog mode */
40
41#define WDT_DEFAULT_TIME	5	/* seconds */
42#define WDT_MAX_TIME		171	/* seconds */
43
44static int wdt_time = WDT_DEFAULT_TIME;
45static bool nowayout = WATCHDOG_NOWAYOUT;
46
47module_param(wdt_time, int, 0);
48MODULE_PARM_DESC(wdt_time, "Watchdog time in seconds. (default="
49					__MODULE_STRING(WDT_DEFAULT_TIME) ")");
50
51#ifdef CONFIG_WATCHDOG_NOWAYOUT
52module_param(nowayout, bool, 0);
53MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
54				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
55#endif
56
57
58static unsigned long ks8695wdt_busy;
59static DEFINE_SPINLOCK(ks8695_lock);
60
61/* ......................................................................... */
62
63/*
64 * Disable the watchdog.
65 */
66static inline void ks8695_wdt_stop(void)
67{
68	unsigned long tmcon;
69
70	spin_lock(&ks8695_lock);
71	/* disable timer0 */
72	tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
73	__raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
74	spin_unlock(&ks8695_lock);
75}
76
77/*
78 * Enable and reset the watchdog.
79 */
80static inline void ks8695_wdt_start(void)
81{
82	unsigned long tmcon;
83	unsigned long tval = wdt_time * KS8695_CLOCK_RATE;
84
85	spin_lock(&ks8695_lock);
86	/* disable timer0 */
87	tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
88	__raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
89
90	/* program timer0 */
91	__raw_writel(tval | T0TC_WATCHDOG, KS8695_TMR_VA + KS8695_T0TC);
92
93	/* re-enable timer0 */
94	tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
95	__raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
96	spin_unlock(&ks8695_lock);
97}
98
99/*
100 * Reload the watchdog timer.  (ie, pat the watchdog)
101 */
102static inline void ks8695_wdt_reload(void)
103{
104	unsigned long tmcon;
105
106	spin_lock(&ks8695_lock);
107	/* disable, then re-enable timer0 */
108	tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON);
109	__raw_writel(tmcon & ~TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
110	__raw_writel(tmcon | TMCON_T0EN, KS8695_TMR_VA + KS8695_TMCON);
111	spin_unlock(&ks8695_lock);
112}
113
114/*
115 * Change the watchdog time interval.
116 */
117static int ks8695_wdt_settimeout(int new_time)
118{
119	/*
120	 * All counting occurs at KS8695_CLOCK_RATE / 128 = 0.256 Hz
121	 *
122	 * Since WDV is a 16-bit counter, the maximum period is
123	 * 65536 / 0.256 = 256 seconds.
124	 */
125	if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
126		return -EINVAL;
127
128	/* Set new watchdog time. It will be used when
129	   ks8695_wdt_start() is called. */
130	wdt_time = new_time;
131	return 0;
132}
133
134/* ......................................................................... */
135
136/*
137 * Watchdog device is opened, and watchdog starts running.
138 */
139static int ks8695_wdt_open(struct inode *inode, struct file *file)
140{
141	if (test_and_set_bit(0, &ks8695wdt_busy))
142		return -EBUSY;
143
144	ks8695_wdt_start();
145	return nonseekable_open(inode, file);
146}
147
148/*
149 * Close the watchdog device.
150 * If CONFIG_WATCHDOG_NOWAYOUT is NOT defined then the watchdog is also
151 *  disabled.
152 */
153static int ks8695_wdt_close(struct inode *inode, struct file *file)
154{
155	/* Disable the watchdog when file is closed */
156	if (!nowayout)
157		ks8695_wdt_stop();
158	clear_bit(0, &ks8695wdt_busy);
159	return 0;
160}
161
162static const struct watchdog_info ks8695_wdt_info = {
163	.identity	= "ks8695 watchdog",
164	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
165};
166
167/*
168 * Handle commands from user-space.
169 */
170static long ks8695_wdt_ioctl(struct file *file, unsigned int cmd,
171							unsigned long arg)
172{
173	void __user *argp = (void __user *)arg;
174	int __user *p = argp;
175	int new_value;
176
177	switch (cmd) {
178	case WDIOC_GETSUPPORT:
179		return copy_to_user(argp, &ks8695_wdt_info,
180					sizeof(ks8695_wdt_info)) ? -EFAULT : 0;
181	case WDIOC_GETSTATUS:
182	case WDIOC_GETBOOTSTATUS:
183		return put_user(0, p);
184	case WDIOC_SETOPTIONS:
185		if (get_user(new_value, p))
186			return -EFAULT;
187		if (new_value & WDIOS_DISABLECARD)
188			ks8695_wdt_stop();
189		if (new_value & WDIOS_ENABLECARD)
190			ks8695_wdt_start();
191		return 0;
192	case WDIOC_KEEPALIVE:
193		ks8695_wdt_reload();	/* pat the watchdog */
194		return 0;
195	case WDIOC_SETTIMEOUT:
196		if (get_user(new_value, p))
197			return -EFAULT;
198		if (ks8695_wdt_settimeout(new_value))
199			return -EINVAL;
200		/* Enable new time value */
201		ks8695_wdt_start();
202		/* Return current value */
203		return put_user(wdt_time, p);
204	case WDIOC_GETTIMEOUT:
205		return put_user(wdt_time, p);
206	default:
207		return -ENOTTY;
208	}
209}
210
211/*
212 * Pat the watchdog whenever device is written to.
213 */
214static ssize_t ks8695_wdt_write(struct file *file, const char *data,
215						size_t len, loff_t *ppos)
216{
217	ks8695_wdt_reload();		/* pat the watchdog */
218	return len;
219}
220
221/* ......................................................................... */
222
223static const struct file_operations ks8695wdt_fops = {
224	.owner		= THIS_MODULE,
225	.llseek		= no_llseek,
226	.unlocked_ioctl	= ks8695_wdt_ioctl,
227	.open		= ks8695_wdt_open,
228	.release	= ks8695_wdt_close,
229	.write		= ks8695_wdt_write,
230};
231
232static struct miscdevice ks8695wdt_miscdev = {
233	.minor		= WATCHDOG_MINOR,
234	.name		= "watchdog",
235	.fops		= &ks8695wdt_fops,
236};
237
238static int ks8695wdt_probe(struct platform_device *pdev)
239{
240	int res;
241
242	if (ks8695wdt_miscdev.parent)
243		return -EBUSY;
244	ks8695wdt_miscdev.parent = &pdev->dev;
245
246	res = misc_register(&ks8695wdt_miscdev);
247	if (res)
248		return res;
249
250	pr_info("KS8695 Watchdog Timer enabled (%d seconds%s)\n",
251		wdt_time, nowayout ? ", nowayout" : "");
252	return 0;
253}
254
255static int ks8695wdt_remove(struct platform_device *pdev)
256{
257	int res;
258
259	res = misc_deregister(&ks8695wdt_miscdev);
260	if (!res)
261		ks8695wdt_miscdev.parent = NULL;
262
263	return res;
264}
265
266static void ks8695wdt_shutdown(struct platform_device *pdev)
267{
268	ks8695_wdt_stop();
269}
270
271#ifdef CONFIG_PM
272
273static int ks8695wdt_suspend(struct platform_device *pdev, pm_message_t message)
274{
275	ks8695_wdt_stop();
276	return 0;
277}
278
279static int ks8695wdt_resume(struct platform_device *pdev)
280{
281	if (ks8695wdt_busy)
282		ks8695_wdt_start();
283	return 0;
284}
285
286#else
287#define ks8695wdt_suspend NULL
288#define ks8695wdt_resume	NULL
289#endif
290
291static struct platform_driver ks8695wdt_driver = {
292	.probe		= ks8695wdt_probe,
293	.remove		= ks8695wdt_remove,
294	.shutdown	= ks8695wdt_shutdown,
295	.suspend	= ks8695wdt_suspend,
296	.resume		= ks8695wdt_resume,
297	.driver		= {
298		.name	= "ks8695_wdt",
299	},
300};
301
302static int __init ks8695_wdt_init(void)
303{
304	/* Check that the heartbeat value is within range;
305	   if not reset to the default */
306	if (ks8695_wdt_settimeout(wdt_time)) {
307		ks8695_wdt_settimeout(WDT_DEFAULT_TIME);
308		pr_info("ks8695_wdt: wdt_time value must be 1 <= wdt_time <= %i"
309					", using %d\n", wdt_time, WDT_MAX_TIME);
310	}
311	return platform_driver_register(&ks8695wdt_driver);
312}
313
314static void __exit ks8695_wdt_exit(void)
315{
316	platform_driver_unregister(&ks8695wdt_driver);
317}
318
319module_init(ks8695_wdt_init);
320module_exit(ks8695_wdt_exit);
321
322MODULE_AUTHOR("Andrew Victor");
323MODULE_DESCRIPTION("Watchdog driver for KS8695");
324MODULE_LICENSE("GPL");
325MODULE_ALIAS("platform:ks8695_wdt");
326