/drivers/watchdog/sa1100_wdt.c

  1/*
  2 *	Watchdog driver for the SA11x0/PXA2xx
  3 *
  4 *	(c) Copyright 2000 Oleg Drokin <green@crimea.edu>
  5 *	    Based on SoftDog driver by Alan Cox <alan@lxorguk.ukuu.org.uk>
  6 *
  7 *	This program is free software; you can redistribute it and/or
  8 *	modify it under the terms of the GNU General Public License
  9 *	as published by the Free Software Foundation; either version
 10 *	2 of the License, or (at your option) any later version.
 11 *
 12 *	Neither Oleg Drokin nor iXcelerator.com admit liability nor provide
 13 *	warranty for any of this software. This material is provided
 14 *	"AS-IS" and at no charge.
 15 *
 16 *	(c) Copyright 2000           Oleg Drokin <green@crimea.edu>
 17 *
 18 *	27/11/2000 Initial release
 19 */
 20#include <linux/module.h>
 21#include <linux/moduleparam.h>
 22#include <linux/types.h>
 23#include <linux/kernel.h>
 24#include <linux/fs.h>
 25#include <linux/miscdevice.h>
 26#include <linux/watchdog.h>
 27#include <linux/init.h>
 28#include <linux/bitops.h>
 29#include <linux/uaccess.h>
 30#include <linux/timex.h>
 31
 32#ifdef CONFIG_ARCH_PXA
 33#include <mach/regs-ost.h>
 34#endif
 35
 36#include <mach/reset.h>
 37#include <mach/hardware.h>
 38
 39static unsigned long oscr_freq;
 40static unsigned long sa1100wdt_users;
 41static unsigned int pre_margin;
 42static int boot_status;
 43
 44/*
 45 *	Allow only one person to hold it open
 46 */
 47static int sa1100dog_open(struct inode *inode, struct file *file)
 48{
 49	if (test_and_set_bit(1, &sa1100wdt_users))
 50		return -EBUSY;
 51
 52	/* Activate SA1100 Watchdog timer */
 53	OSMR3 = OSCR + pre_margin;
 54	OSSR = OSSR_M3;
 55	OWER = OWER_WME;
 56	OIER |= OIER_E3;
 57	return nonseekable_open(inode, file);
 58}
 59
 60/*
 61 * The watchdog cannot be disabled.
 62 *
 63 * Previous comments suggested that turning off the interrupt by
 64 * clearing OIER[E3] would prevent the watchdog timing out but this
 65 * does not appear to be true (at least on the PXA255).
 66 */
 67static int sa1100dog_release(struct inode *inode, struct file *file)
 68{
 69	printk(KERN_CRIT "WATCHDOG: Device closed - timer will not stop\n");
 70	clear_bit(1, &sa1100wdt_users);
 71	return 0;
 72}
 73
 74static ssize_t sa1100dog_write(struct file *file, const char __user *data,
 75						size_t len, loff_t *ppos)
 76{
 77	if (len)
 78		/* Refresh OSMR3 timer. */
 79		OSMR3 = OSCR + pre_margin;
 80	return len;
 81}
 82
 83static const struct watchdog_info ident = {
 84	.options	= WDIOF_CARDRESET | WDIOF_SETTIMEOUT
 85				| WDIOF_KEEPALIVEPING,
 86	.identity	= "SA1100/PXA255 Watchdog",
 87	.firmware_version	= 1,
 88};
 89
 90static long sa1100dog_ioctl(struct file *file, unsigned int cmd,
 91							unsigned long arg)
 92{
 93	int ret = -ENOTTY;
 94	int time;
 95	void __user *argp = (void __user *)arg;
 96	int __user *p = argp;
 97
 98	switch (cmd) {
 99	case WDIOC_GETSUPPORT:
100		ret = copy_to_user(argp, &ident,
101				   sizeof(ident)) ? -EFAULT : 0;
102		break;
103
104	case WDIOC_GETSTATUS:
105		ret = put_user(0, p);
106		break;
107
108	case WDIOC_GETBOOTSTATUS:
109		ret = put_user(boot_status, p);
110		break;
111
112	case WDIOC_KEEPALIVE:
113		OSMR3 = OSCR + pre_margin;
114		ret = 0;
115		break;
116
117	case WDIOC_SETTIMEOUT:
118		ret = get_user(time, p);
119		if (ret)
120			break;
121
122		if (time <= 0 || (oscr_freq * (long long)time >= 0xffffffff)) {
123			ret = -EINVAL;
124			break;
125		}
126
127		pre_margin = oscr_freq * time;
128		OSMR3 = OSCR + pre_margin;
129		/*fall through*/
130
131	case WDIOC_GETTIMEOUT:
132		ret = put_user(pre_margin / oscr_freq, p);
133		break;
134	}
135	return ret;
136}
137
138static const struct file_operations sa1100dog_fops = {
139	.owner		= THIS_MODULE,
140	.llseek		= no_llseek,
141	.write		= sa1100dog_write,
142	.unlocked_ioctl	= sa1100dog_ioctl,
143	.open		= sa1100dog_open,
144	.release	= sa1100dog_release,
145};
146
147static struct miscdevice sa1100dog_miscdev = {
148	.minor		= WATCHDOG_MINOR,
149	.name		= "watchdog",
150	.fops		= &sa1100dog_fops,
151};
152
153static int margin __initdata = 60;		/* (secs) Default is 1 minute */
154
155static int __init sa1100dog_init(void)
156{
157	int ret;
158
159	oscr_freq = get_clock_tick_rate();
160
161	/*
162	 * Read the reset status, and save it for later.  If
163	 * we suspend, RCSR will be cleared, and the watchdog
164	 * reset reason will be lost.
165	 */
166	boot_status = (reset_status & RESET_STATUS_WATCHDOG) ?
167				WDIOF_CARDRESET : 0;
168	pre_margin = oscr_freq * margin;
169
170	ret = misc_register(&sa1100dog_miscdev);
171	if (ret == 0)
172		printk(KERN_INFO
173			"SA1100/PXA2xx Watchdog Timer: timer margin %d sec\n",
174						margin);
175	return ret;
176}
177
178static void __exit sa1100dog_exit(void)
179{
180	misc_deregister(&sa1100dog_miscdev);
181}
182
183module_init(sa1100dog_init);
184module_exit(sa1100dog_exit);
185
186MODULE_AUTHOR("Oleg Drokin <green@crimea.edu>");
187MODULE_DESCRIPTION("SA1100/PXA2xx Watchdog");
188
189module_param(margin, int, 0);
190MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
191
192MODULE_LICENSE("GPL");
193MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);