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