/drivers/char/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@redhat.com>
  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/config.h>
 21#include <linux/module.h>
 22#include <linux/moduleparam.h>
 23#include <linux/types.h>
 24#include <linux/kernel.h>
 25#include <linux/fs.h>
 26#include <linux/miscdevice.h>
 27#include <linux/watchdog.h>
 28#include <linux/init.h>
 29
 30#ifdef CONFIG_ARCH_PXA
 31#include <asm/arch/pxa-regs.h>
 32#endif
 33
 34#include <asm/hardware.h>
 35#include <asm/bitops.h>
 36#include <asm/uaccess.h>
 37
 38#define OSCR_FREQ		CLOCK_TICK_RATE
 39#define SA1100_CLOSE_MAGIC	(0x5afc4453)
 40
 41static unsigned long sa1100wdt_users;
 42static int expect_close;
 43static int pre_margin;
 44static int boot_status;
 45#ifdef CONFIG_WATCHDOG_NOWAYOUT
 46static int nowayout = 1;
 47#else
 48static int nowayout = 0;
 49#endif
 50
 51/*
 52 *	Allow only one person to hold it open
 53 */
 54static int sa1100dog_open(struct inode *inode, struct file *file)
 55{
 56	nonseekable_open(inode, file);
 57	if (test_and_set_bit(1,&sa1100wdt_users))
 58		return -EBUSY;
 59
 60	/* Activate SA1100 Watchdog timer */
 61	OSMR3 = OSCR + pre_margin;
 62	OSSR = OSSR_M3;
 63	OWER = OWER_WME;
 64	OIER |= OIER_E3;
 65	return 0;
 66}
 67
 68/*
 69 *	Shut off the timer.
 70 * 	Lock it in if it's a module and we defined ...NOWAYOUT
 71 *	Oddly, the watchdog can only be enabled, but we can turn off
 72 *	the interrupt, which appears to prevent the watchdog timing out.
 73 */
 74static int sa1100dog_release(struct inode *inode, struct file *file)
 75{
 76	OSMR3 = OSCR + pre_margin;
 77
 78	if (expect_close == SA1100_CLOSE_MAGIC) {
 79		OIER &= ~OIER_E3;
 80	} else {
 81		printk(KERN_CRIT "WATCHDOG: WDT device closed unexpectedly.  WDT will not stop!\n");
 82	}
 83
 84	clear_bit(1, &sa1100wdt_users);
 85	expect_close = 0;
 86
 87	return 0;
 88}
 89
 90static ssize_t sa1100dog_write(struct file *file, const char *data, size_t len, loff_t *ppos)
 91{
 92	if (len) {
 93		if (!nowayout) {
 94			size_t i;
 95
 96			expect_close = 0;
 97
 98			for (i = 0; i != len; i++) {
 99				char c;
100
101				if (get_user(c, data + i))
102					return -EFAULT;
103				if (c == 'V')
104					expect_close = SA1100_CLOSE_MAGIC;
105			}
106		}
107		/* Refresh OSMR3 timer. */
108		OSMR3 = OSCR + pre_margin;
109	}
110
111	return len;
112}
113
114static struct watchdog_info ident = {
115	.options	= WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
116			  WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
117	.identity	= "SA1100 Watchdog",
118};
119
120static int sa1100dog_ioctl(struct inode *inode, struct file *file,
121	unsigned int cmd, unsigned long arg)
122{
123	int ret = -ENOIOCTLCMD;
124	int time;
125
126	switch (cmd) {
127	case WDIOC_GETSUPPORT:
128		ret = copy_to_user((struct watchdog_info *)arg, &ident,
129				   sizeof(ident)) ? -EFAULT : 0;
130		break;
131
132	case WDIOC_GETSTATUS:
133		ret = put_user(0, (int *)arg);
134		break;
135
136	case WDIOC_GETBOOTSTATUS:
137		ret = put_user(boot_status, (int *)arg);
138		break;
139
140	case WDIOC_SETTIMEOUT:
141		ret = get_user(time, (int *)arg);
142		if (ret)
143			break;
144
145		if (time <= 0 || time > 255) {
146			ret = -EINVAL;
147			break;
148		}
149
150		pre_margin = OSCR_FREQ * time;
151		OSMR3 = OSCR + pre_margin;
152		/*fall through*/
153
154	case WDIOC_GETTIMEOUT:
155		ret = put_user(pre_margin / OSCR_FREQ, (int *)arg);
156		break;
157
158	case WDIOC_KEEPALIVE:
159		OSMR3 = OSCR + pre_margin;
160		ret = 0;
161		break;
162	}
163	return ret;
164}
165
166static struct file_operations sa1100dog_fops =
167{
168	.owner		= THIS_MODULE,
169	.llseek		= no_llseek,
170	.write		= sa1100dog_write,
171	.ioctl		= sa1100dog_ioctl,
172	.open		= sa1100dog_open,
173	.release	= sa1100dog_release,
174};
175
176static struct miscdevice sa1100dog_miscdev =
177{
178	.minor		= WATCHDOG_MINOR,
179	.name		= "SA1100/PXA2xx watchdog",
180	.fops		= &sa1100dog_fops,
181};
182
183static int margin __initdata = 60;		/* (secs) Default is 1 minute */
184
185static int __init sa1100dog_init(void)
186{
187	int ret;
188
189	/*
190	 * Read the reset status, and save it for later.  If
191	 * we suspend, RCSR will be cleared, and the watchdog
192	 * reset reason will be lost.
193	 */
194	boot_status = (RCSR & RCSR_WDR) ? WDIOF_CARDRESET : 0;
195	pre_margin = OSCR_FREQ * margin;
196
197	ret = misc_register(&sa1100dog_miscdev);
198	if (ret == 0)
199		printk("SA1100/PXA2xx Watchdog Timer: timer margin %d sec\n",
200		       margin);
201
202	return ret;
203}
204
205static void __exit sa1100dog_exit(void)
206{
207	misc_deregister(&sa1100dog_miscdev);
208}
209
210module_init(sa1100dog_init);
211module_exit(sa1100dog_exit);
212
213MODULE_AUTHOR("Oleg Drokin <green@crimea.edu>");
214MODULE_DESCRIPTION("SA1100/PXA2xx Watchdog");
215
216module_param(margin, int, 0);
217MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
218
219module_param(nowayout, int, 0);
220MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
221
222MODULE_LICENSE("GPL");
223MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);