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	misc_deregister(&ks8695wdt_miscdev);
258	ks8695wdt_miscdev.parent = NULL;
259
260	return 0;
261}
262
263static void ks8695wdt_shutdown(struct platform_device *pdev)
264{
265	ks8695_wdt_stop();
266}
267
268#ifdef CONFIG_PM
269
270static int ks8695wdt_suspend(struct platform_device *pdev, pm_message_t message)
271{
272	ks8695_wdt_stop();
273	return 0;
274}
275
276static int ks8695wdt_resume(struct platform_device *pdev)
277{
278	if (ks8695wdt_busy)
279		ks8695_wdt_start();
280	return 0;
281}
282
283#else
284#define ks8695wdt_suspend NULL
285#define ks8695wdt_resume	NULL
286#endif
287
288static struct platform_driver ks8695wdt_driver = {
289	.probe		= ks8695wdt_probe,
290	.remove		= ks8695wdt_remove,
291	.shutdown	= ks8695wdt_shutdown,
292	.suspend	= ks8695wdt_suspend,
293	.resume		= ks8695wdt_resume,
294	.driver		= {
295		.name	= "ks8695_wdt",
296	},
297};
298
299static int __init ks8695_wdt_init(void)
300{
301	/* Check that the heartbeat value is within range;
302	   if not reset to the default */
303	if (ks8695_wdt_settimeout(wdt_time)) {
304		ks8695_wdt_settimeout(WDT_DEFAULT_TIME);
305		pr_info("ks8695_wdt: wdt_time value must be 1 <= wdt_time <= %i"
306					", using %d\n", wdt_time, WDT_MAX_TIME);
307	}
308	return platform_driver_register(&ks8695wdt_driver);
309}
310
311static void __exit ks8695_wdt_exit(void)
312{
313	platform_driver_unregister(&ks8695wdt_driver);
314}
315
316module_init(ks8695_wdt_init);
317module_exit(ks8695_wdt_exit);
318
319MODULE_AUTHOR("Andrew Victor");
320MODULE_DESCRIPTION("Watchdog driver for KS8695");
321MODULE_LICENSE("GPL");
322MODULE_ALIAS("platform:ks8695_wdt");