2 * Watchdog driver for the mpcore watchdog timer
4 * (c) Copyright 2004 ARM Limited
6 * Based on the SoftDog driver:
7 * (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
8 * http://www.redhat.com
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or (at your option) any later version.
15 * Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
16 * warranty for any of this software. This material is provided
17 * "AS-IS" and at no charge.
19 * (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
22 #include <linux/module.h>
23 #include <linux/moduleparam.h>
24 #include <linux/types.h>
25 #include <linux/miscdevice.h>
26 #include <linux/watchdog.h>
28 #include <linux/reboot.h>
29 #include <linux/init.h>
30 #include <linux/interrupt.h>
31 #include <linux/platform_device.h>
33 #include <asm/hardware/arm_twd.h>
34 #include <asm/uaccess.h>
37 unsigned long timer_alive;
45 static struct platform_device *mpcore_wdt_dev;
47 extern unsigned int mpcore_timer_rate;
49 #define TIMER_MARGIN 60
50 static int mpcore_margin = TIMER_MARGIN;
51 module_param(mpcore_margin, int, 0);
52 MODULE_PARM_DESC(mpcore_margin, "MPcore timer margin in seconds. (0<mpcore_margin<65536, default=" __MODULE_STRING(TIMER_MARGIN) ")");
54 static int nowayout = WATCHDOG_NOWAYOUT;
55 module_param(nowayout, int, 0);
56 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
58 #define ONLY_TESTING 0
59 static int mpcore_noboot = ONLY_TESTING;
60 module_param(mpcore_noboot, int, 0);
61 MODULE_PARM_DESC(mpcore_noboot, "MPcore watchdog action, set to 1 to ignore reboots, 0 to reboot (default=" __MODULE_STRING(ONLY_TESTING) ")");
64 * This is the interrupt handler. Note that we only use this
65 * in testing mode, so don't actually do a reboot here.
67 static irqreturn_t mpcore_wdt_fire(int irq, void *arg)
69 struct mpcore_wdt *wdt = arg;
71 /* Check it really was our interrupt */
72 if (readl(wdt->base + TWD_WDOG_INTSTAT)) {
73 dev_printk(KERN_CRIT, wdt->dev, "Triggered - Reboot ignored.\n");
75 /* Clear the interrupt on the watchdog */
76 writel(1, wdt->base + TWD_WDOG_INTSTAT);
85 * mpcore_wdt_keepalive - reload the timer
87 * Note that the spec says a DIFFERENT value must be written to the reload
88 * register each time. The "perturb" variable deals with this by adding 1
89 * to the count every other time the function is called.
91 static void mpcore_wdt_keepalive(struct mpcore_wdt *wdt)
95 /* Assume prescale is set to 256 */
96 count = (mpcore_timer_rate / 256) * mpcore_margin;
98 /* Reload the counter */
99 writel(count + wdt->perturb, wdt->base + TWD_WDOG_LOAD);
101 wdt->perturb = wdt->perturb ? 0 : 1;
104 static void mpcore_wdt_stop(struct mpcore_wdt *wdt)
106 writel(0x12345678, wdt->base + TWD_WDOG_DISABLE);
107 writel(0x87654321, wdt->base + TWD_WDOG_DISABLE);
108 writel(0x0, wdt->base + TWD_WDOG_CONTROL);
111 static void mpcore_wdt_start(struct mpcore_wdt *wdt)
113 dev_printk(KERN_INFO, wdt->dev, "enabling watchdog.\n");
115 /* This loads the count register but does NOT start the count yet */
116 mpcore_wdt_keepalive(wdt);
119 /* Enable watchdog - prescale=256, watchdog mode=0, enable=1 */
120 writel(0x0000FF01, wdt->base + TWD_WDOG_CONTROL);
122 /* Enable watchdog - prescale=256, watchdog mode=1, enable=1 */
123 writel(0x0000FF09, wdt->base + TWD_WDOG_CONTROL);
127 static int mpcore_wdt_set_heartbeat(int t)
129 if (t < 0x0001 || t > 0xFFFF)
137 * /dev/watchdog handling
139 static int mpcore_wdt_open(struct inode *inode, struct file *file)
141 struct mpcore_wdt *wdt = platform_get_drvdata(mpcore_wdt_dev);
143 if (test_and_set_bit(0, &wdt->timer_alive))
147 __module_get(THIS_MODULE);
149 file->private_data = wdt;
154 mpcore_wdt_start(wdt);
156 return nonseekable_open(inode, file);
159 static int mpcore_wdt_release(struct inode *inode, struct file *file)
161 struct mpcore_wdt *wdt = file->private_data;
164 * Shut off the timer.
165 * Lock it in if it's a module and we set nowayout
167 if (wdt->expect_close == 42) {
168 mpcore_wdt_stop(wdt);
170 dev_printk(KERN_CRIT, wdt->dev, "unexpected close, not stopping watchdog!\n");
171 mpcore_wdt_keepalive(wdt);
173 clear_bit(0, &wdt->timer_alive);
174 wdt->expect_close = 0;
178 static ssize_t mpcore_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
180 struct mpcore_wdt *wdt = file->private_data;
189 /* In case it was set long ago */
190 wdt->expect_close = 0;
192 for (i = 0; i != len; i++) {
195 if (get_user(c, data + i))
198 wdt->expect_close = 42;
201 mpcore_wdt_keepalive(wdt);
206 static struct watchdog_info ident = {
207 .options = WDIOF_SETTIMEOUT |
208 WDIOF_KEEPALIVEPING |
210 .identity = "MPcore Watchdog",
213 static int mpcore_wdt_ioctl(struct inode *inode, struct file *file,
214 unsigned int cmd, unsigned long arg)
216 struct mpcore_wdt *wdt = file->private_data;
219 struct watchdog_info ident;
223 if (_IOC_DIR(cmd) && _IOC_SIZE(cmd) > sizeof(uarg))
226 if (_IOC_DIR(cmd) & _IOC_WRITE) {
227 ret = copy_from_user(&uarg, (void __user *)arg, _IOC_SIZE(cmd));
233 case WDIOC_GETSUPPORT:
238 case WDIOC_SETOPTIONS:
240 if (uarg.i & WDIOS_DISABLECARD) {
241 mpcore_wdt_stop(wdt);
244 if (uarg.i & WDIOS_ENABLECARD) {
245 mpcore_wdt_start(wdt);
250 case WDIOC_GETSTATUS:
251 case WDIOC_GETBOOTSTATUS:
256 case WDIOC_KEEPALIVE:
257 mpcore_wdt_keepalive(wdt);
261 case WDIOC_SETTIMEOUT:
262 ret = mpcore_wdt_set_heartbeat(uarg.i);
266 mpcore_wdt_keepalive(wdt);
268 case WDIOC_GETTIMEOUT:
269 uarg.i = mpcore_margin;
277 if (ret == 0 && _IOC_DIR(cmd) & _IOC_READ) {
278 ret = copy_to_user((void __user *)arg, &uarg, _IOC_SIZE(cmd));
286 * System shutdown handler. Turn off the watchdog if we're
287 * restarting or halting the system.
289 static void mpcore_wdt_shutdown(struct platform_device *dev)
291 struct mpcore_wdt *wdt = platform_get_drvdata(dev);
293 if (system_state == SYSTEM_RESTART || system_state == SYSTEM_HALT)
294 mpcore_wdt_stop(wdt);
300 static const struct file_operations mpcore_wdt_fops = {
301 .owner = THIS_MODULE,
303 .write = mpcore_wdt_write,
304 .ioctl = mpcore_wdt_ioctl,
305 .open = mpcore_wdt_open,
306 .release = mpcore_wdt_release,
309 static struct miscdevice mpcore_wdt_miscdev = {
310 .minor = WATCHDOG_MINOR,
312 .fops = &mpcore_wdt_fops,
315 static int __devinit mpcore_wdt_probe(struct platform_device *dev)
317 struct mpcore_wdt *wdt;
318 struct resource *res;
321 /* We only accept one device, and it must have an id of -1 */
325 res = platform_get_resource(dev, IORESOURCE_MEM, 0);
331 wdt = kmalloc(sizeof(struct mpcore_wdt), GFP_KERNEL);
336 memset(wdt, 0, sizeof(struct mpcore_wdt));
338 wdt->dev = &dev->dev;
339 wdt->irq = platform_get_irq(dev, 0);
344 wdt->base = ioremap(res->start, res->end - res->start + 1);
350 mpcore_wdt_miscdev.dev = &dev->dev;
351 ret = misc_register(&mpcore_wdt_miscdev);
353 dev_printk(KERN_ERR, _dev, "cannot register miscdev on minor=%d (err=%d)\n",
354 WATCHDOG_MINOR, ret);
358 ret = request_irq(wdt->irq, mpcore_wdt_fire, IRQF_DISABLED, "mpcore_wdt", wdt);
360 dev_printk(KERN_ERR, _dev, "cannot register IRQ%d for watchdog\n", wdt->irq);
364 mpcore_wdt_stop(wdt);
365 platform_set_drvdata(&dev->dev, wdt);
366 mpcore_wdt_dev = dev;
371 misc_deregister(&mpcore_wdt_miscdev);
380 static int __devexit mpcore_wdt_remove(struct platform_device *dev)
382 struct mpcore_wdt *wdt = platform_get_drvdata(dev);
384 platform_set_drvdata(dev, NULL);
386 misc_deregister(&mpcore_wdt_miscdev);
388 mpcore_wdt_dev = NULL;
390 free_irq(wdt->irq, wdt);
396 static struct platform_driver mpcore_wdt_driver = {
397 .probe = mpcore_wdt_probe,
398 .remove = __devexit_p(mpcore_wdt_remove),
399 .shutdown = mpcore_wdt_shutdown,
401 .owner = THIS_MODULE,
402 .name = "mpcore_wdt",
406 static char banner[] __initdata = KERN_INFO "MPcore Watchdog Timer: 0.1. mpcore_noboot=%d mpcore_margin=%d sec (nowayout= %d)\n";
408 static int __init mpcore_wdt_init(void)
411 * Check that the margin value is within it's range;
412 * if not reset to the default
414 if (mpcore_wdt_set_heartbeat(mpcore_margin)) {
415 mpcore_wdt_set_heartbeat(TIMER_MARGIN);
416 printk(KERN_INFO "mpcore_margin value must be 0<mpcore_margin<65536, using %d\n",
420 printk(banner, mpcore_noboot, mpcore_margin, nowayout);
422 return platform_driver_register(&mpcore_wdt_driver);
425 static void __exit mpcore_wdt_exit(void)
427 platform_driver_unregister(&mpcore_wdt_driver);
430 module_init(mpcore_wdt_init);
431 module_exit(mpcore_wdt_exit);
433 MODULE_AUTHOR("ARM Limited");
434 MODULE_DESCRIPTION("MPcore Watchdog Device Driver");
435 MODULE_LICENSE("GPL");
436 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);