[linux-2.6-block.git] / drivers / watchdog / sb_wdog.c

/*
 * Watchdog driver for SiByte SB1 SoCs
 *
 * Copyright (C) 2007 OnStor, Inc. * Andrew Sharp <andy.sharp@onstor.com>
 *
 * This driver is intended to make the second of two hardware watchdogs
 * on the Sibyte 12XX and 11XX SoCs available to the user.  There are two
 * such devices available on the SoC, but it seems that there isn't an
 * enumeration class for watchdogs in Linux like there is for RTCs.
 * The second is used rather than the first because it uses IRQ 1,
 * thereby avoiding all that IRQ 0 problematic nonsense.
 *
 * I have not tried this driver on a 1480 processor; it might work
 * just well enough to really screw things up.
 *
 * It is a simple timer, and there is an interrupt that is raised the
 * first time the timer expires.  The second time it expires, the chip
 * is reset and there is no way to redirect that NMI.  Which could
 * be problematic in some cases where this chip is sitting on the HT
 * bus and has just taken responsibility for providing a cache block.
 * Since the reset can't be redirected to the external reset pin, it is
 * possible that other HT connected processors might hang and not reset.
 * For Linux, a soft reset would probably be even worse than a hard reset.
 * There you have it.
 *
 * The timer takes 23 bits of a 64 bit register (?) as a count value,
 * and decrements the count every microsecond, for a max value of
 * 0x7fffff usec or about 8.3ish seconds.
 *
 * This watchdog borrows some user semantics from the softdog driver,
 * in that if you close the fd, it leaves the watchdog running, unless
 * you previously wrote a 'V' to the fd, in which case it disables
 * the watchdog when you close the fd like some other drivers.
 *
 * Based on various other watchdog drivers, which are probably all
 * loosely based on something Alan Cox wrote years ago.
 *
 *	(c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
 *				http://www.redhat.com
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	version 1 or 2 as published by the Free Software Foundation.
 *
 */
#include <linux/module.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/fs.h>
#include <linux/reboot.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/interrupt.h>

#include <asm/sibyte/sb1250.h>
#include <asm/sibyte/sb1250_regs.h>
#include <asm/sibyte/sb1250_int.h>
#include <asm/sibyte/sb1250_scd.h>


/*
 * set the initial count value of a timer
 *
 * wdog is the iomem address of the cfg register
 */
void sbwdog_set(char __iomem *wdog, unsigned long t)
{
	__raw_writeb(0, wdog - 0x10);
	__raw_writeq(t & 0x7fffffUL, wdog);
}

/*
 * cause the timer to [re]load it's initial count and start counting
 * all over again
 *
 * wdog is the iomem address of the cfg register
 */
void sbwdog_pet(char __iomem *wdog)
{
	__raw_writeb(__raw_readb(wdog) | 1, wdog);
}

static unsigned long sbwdog_gate; /* keeps it to one thread only */
static char __iomem *kern_dog = (char __iomem *)(IO_BASE + (A_SCD_WDOG_CFG_0));
static char __iomem *user_dog = (char __iomem *)(IO_BASE + (A_SCD_WDOG_CFG_1));
static unsigned long timeout = 0x7fffffUL;	/* useconds: 8.3ish secs. */
static int expect_close;

static struct watchdog_info ident = {
	.options	= WDIOF_CARDRESET | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
	.identity	= "SiByte Watchdog",
};

/*
 * Allow only a single thread to walk the dog
 */
static int sbwdog_open(struct inode *inode, struct file *file)
{
	nonseekable_open(inode, file);
	if (test_and_set_bit(0, &sbwdog_gate)) {
		return -EBUSY;
	}
	__module_get(THIS_MODULE);

	/*
	 * Activate the timer
	 */
	sbwdog_set(user_dog, timeout);
	__raw_writeb(1, user_dog);

	return 0;
}

/*
 * Put the dog back in the kennel.
 */
static int sbwdog_release(struct inode *inode, struct file *file)
{
	if (expect_close == 42) {
		__raw_writeb(0, user_dog);
		module_put(THIS_MODULE);
	} else {
		printk(KERN_CRIT "%s: Unexpected close, not stopping watchdog!\n",
			ident.identity);
		sbwdog_pet(user_dog);
	}
	clear_bit(0, &sbwdog_gate);
	expect_close = 0;

	return 0;
}

/*
 * 42 - the answer
 */
static ssize_t sbwdog_write(struct file *file, const char __user *data,
			size_t len, loff_t *ppos)
{
	int i;

	if (len) {
		/*
		 * restart the timer
		 */
		expect_close = 0;

		for (i = 0; i != len; i++) {
			char c;

			if (get_user(c, data + i)) {
				return -EFAULT;
			}
			if (c == 'V') {
				expect_close = 42;
			}
		}
		sbwdog_pet(user_dog);
	}

	return len;
}

static int sbwdog_ioctl(struct inode *inode, struct file *file,
			unsigned int cmd, unsigned long arg)
{
	int ret = -ENOTTY;
	unsigned long time;
	void __user *argp = (void __user *)arg;
	int __user *p = argp;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
		break;

	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		ret = put_user(0, p);
		break;

	case WDIOC_SETTIMEOUT:
		ret = get_user(time, p);
		if (ret) {
			break;
		}

		time *= 1000000;
		if (time > 0x7fffffUL) {
			ret = -EINVAL;
			break;
		}
		timeout = time;
		sbwdog_set(user_dog, timeout);
		sbwdog_pet(user_dog);

	case WDIOC_GETTIMEOUT:
		/*
		 * get the remaining count from the ... count register
		 * which is 1*8 before the config register
		 */
		ret = put_user(__raw_readq(user_dog - 8) / 1000000, p);
		break;

	case WDIOC_KEEPALIVE:
		sbwdog_pet(user_dog);
		ret = 0;
		break;
	}
	return ret;
}

/*
 *	Notifier for system down
 */
static int
sbwdog_notify_sys(struct notifier_block *this, unsigned long code, void *erf)
{
	if (code == SYS_DOWN || code == SYS_HALT) {
		/*
		 * sit and sit
		 */
		__raw_writeb(0, user_dog);
		__raw_writeb(0, kern_dog);
	}

	return NOTIFY_DONE;
}

static const struct file_operations sbwdog_fops =
{
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.write		= sbwdog_write,
	.ioctl		= sbwdog_ioctl,
	.open		= sbwdog_open,
	.release	= sbwdog_release,
};

static struct miscdevice sbwdog_miscdev =
{
	.minor		= WATCHDOG_MINOR,
	.name		= "watchdog",
	.fops		= &sbwdog_fops,
};

static struct notifier_block sbwdog_notifier = {
	.notifier_call	= sbwdog_notify_sys,
};

/*
 * interrupt handler
 *
 * doesn't do a whole lot for user, but oh so cleverly written so kernel
 * code can use it to re-up the watchdog, thereby saving the kernel from
 * having to create and maintain a timer, just to tickle another timer,
 * which is just so wrong.
 */
irqreturn_t sbwdog_interrupt(int irq, void *addr)
{
	unsigned long wd_init;
	char *wd_cfg_reg = (char *)addr;
	u8 cfg;

	cfg = __raw_readb(wd_cfg_reg);
	wd_init = __raw_readq(wd_cfg_reg - 8) & 0x7fffff;

	/*
	 * if it's the second watchdog timer, it's for those users
	 */
	if (wd_cfg_reg == user_dog) {
		printk(KERN_CRIT
			"%s in danger of initiating system reset in %ld.%01ld seconds\n",
			ident.identity, wd_init / 1000000, (wd_init / 100000) % 10);
	} else {
		cfg |= 1;
	}

	__raw_writeb(cfg, wd_cfg_reg);

	return IRQ_HANDLED;
}

static int __init sbwdog_init(void)
{
	int ret;

	/*
	 * register a reboot notifier
	 */
	ret = register_reboot_notifier(&sbwdog_notifier);
	if (ret) {
		printk (KERN_ERR "%s: cannot register reboot notifier (err=%d)\n",
			ident.identity, ret);
		return ret;
	}

	/*
	 * get the resources
	 */
	ret = misc_register(&sbwdog_miscdev);
	if (ret == 0) {
		printk(KERN_INFO "%s: timeout is %ld.%ld secs\n", ident.identity,
			timeout / 1000000, (timeout / 100000) % 10);
	}

	ret = request_irq(1, sbwdog_interrupt, IRQF_DISABLED | IRQF_SHARED,
		ident.identity, (void *)user_dog);
	if (ret) {
		printk(KERN_ERR "%s: failed to request irq 1 - %d\n", ident.identity,
			ret);
		misc_deregister(&sbwdog_miscdev);
	}

	return ret;
}

static void __exit sbwdog_exit(void)
{
	misc_deregister(&sbwdog_miscdev);
}

module_init(sbwdog_init);
module_exit(sbwdog_exit);

MODULE_AUTHOR("Andrew Sharp <andy.sharp@onstor.com>");
MODULE_DESCRIPTION("SiByte Watchdog");

module_param(timeout, ulong, 0);
MODULE_PARM_DESC(timeout,
	"Watchdog timeout in microseconds (max/default 8388607 or 8.3ish secs)");

MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

/*
 * example code that can be put in a platform code area to utilize the
 * first watchdog timer for the kernels own purpose.

 void
platform_wd_setup(void)
{
	int ret;

	ret = request_irq(0, sbwdog_interrupt, IRQF_DISABLED | IRQF_SHARED,
		"Kernel Watchdog", IOADDR(A_SCD_WDOG_CFG_0));
	if (ret) {
		printk(KERN_CRIT "Watchdog IRQ zero(0) failed to be requested - %d\n",
			ret);
	}
}


 */
Commit	Line	Data
75c752e6 AS	1	/*
	2	* Watchdog driver for SiByte SB1 SoCs
	3	*
	4	* Copyright (C) 2007 OnStor, Inc. * Andrew Sharp <andy.sharp@onstor.com>
	5	*
	6	* This driver is intended to make the second of two hardware watchdogs
	7	* on the Sibyte 12XX and 11XX SoCs available to the user. There are two
	8	* such devices available on the SoC, but it seems that there isn't an
	9	* enumeration class for watchdogs in Linux like there is for RTCs.
	10	* The second is used rather than the first because it uses IRQ 1,
	11	* thereby avoiding all that IRQ 0 problematic nonsense.
	12	*
	13	* I have not tried this driver on a 1480 processor; it might work
	14	* just well enough to really screw things up.
	15	*
	16	* It is a simple timer, and there is an interrupt that is raised the
	17	* first time the timer expires. The second time it expires, the chip
	18	* is reset and there is no way to redirect that NMI. Which could
	19	* be problematic in some cases where this chip is sitting on the HT
	20	* bus and has just taken responsibility for providing a cache block.
	21	* Since the reset can't be redirected to the external reset pin, it is
	22	* possible that other HT connected processors might hang and not reset.
	23	* For Linux, a soft reset would probably be even worse than a hard reset.
	24	* There you have it.
	25	*
	26	* The timer takes 23 bits of a 64 bit register (?) as a count value,
	27	* and decrements the count every microsecond, for a max value of
	28	* 0x7fffff usec or about 8.3ish seconds.
	29	*
	30	* This watchdog borrows some user semantics from the softdog driver,
	31	* in that if you close the fd, it leaves the watchdog running, unless
	32	* you previously wrote a 'V' to the fd, in which case it disables
	33	* the watchdog when you close the fd like some other drivers.
	34	*
	35	* Based on various other watchdog drivers, which are probably all
	36	* loosely based on something Alan Cox wrote years ago.
	37	*
	38	* (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
	39	* http://www.redhat.com
	40	*
	41	* This program is free software; you can redistribute it and/or
	42	* modify it under the terms of the GNU General Public License
	43	* version 1 or 2 as published by the Free Software Foundation.
	44	*
	45	*/
	46	#include <linux/module.h>
	47	#include <linux/io.h>
	48	#include <linux/uaccess.h>
	49	#include <linux/fs.h>
	50	#include <linux/reboot.h>
	51	#include <linux/miscdevice.h>
	52	#include <linux/watchdog.h>
	53	#include <linux/interrupt.h>
	54
	55	#include <asm/sibyte/sb1250.h>
	56	#include <asm/sibyte/sb1250_regs.h>
	57	#include <asm/sibyte/sb1250_int.h>
	58	#include <asm/sibyte/sb1250_scd.h>
	59
	60
	61	/*
	62	* set the initial count value of a timer
	63	*
	64	* wdog is the iomem address of the cfg register
65	*/
66	void sbwdog_set(char __iomem *wdog, unsigned long t)
67	{
68	__raw_writeb(0, wdog - 0x10);
69	__raw_writeq(t & 0x7fffffUL, wdog);
70	}
71
72	/*
73	* cause the timer to [re]load it's initial count and start counting
74	* all over again
75	*
76	* wdog is the iomem address of the cfg register
77	*/
78	void sbwdog_pet(char __iomem *wdog)
79	{
80	__raw_writeb(__raw_readb(wdog) \| 1, wdog);
81	}
82
83	static unsigned long sbwdog_gate; /* keeps it to one thread only */
84	static char __iomem kern_dog = (char __iomem )(IO_BASE + (A_SCD_WDOG_CFG_0));
85	static char __iomem user_dog = (char __iomem )(IO_BASE + (A_SCD_WDOG_CFG_1));
86	static unsigned long timeout = 0x7fffffUL; /* useconds: 8.3ish secs. */
87	static int expect_close;
88
89	static struct watchdog_info ident = {
90	.options = WDIOF_CARDRESET \| WDIOF_SETTIMEOUT \| WDIOF_KEEPALIVEPING,
91	.identity = "SiByte Watchdog",
92	};
93
94	/*
95	* Allow only a single thread to walk the dog
96	*/
97	static int sbwdog_open(struct inode inode, struct file file)
98	{
99	nonseekable_open(inode, file);
100	if (test_and_set_bit(0, &sbwdog_gate)) {
101	return -EBUSY;
102	}
103	__module_get(THIS_MODULE);
104
105	/*
106	* Activate the timer
107	*/
108	sbwdog_set(user_dog, timeout);
109	__raw_writeb(1, user_dog);
110
111	return 0;
112	}
113
114	/*
115	* Put the dog back in the kennel.
116	*/
117	static int sbwdog_release(struct inode inode, struct file file)
118	{
119	if (expect_close == 42) {
120	__raw_writeb(0, user_dog);
121	module_put(THIS_MODULE);
122	} else {
123	printk(KERN_CRIT "%s: Unexpected close, not stopping watchdog!\n",
124	ident.identity);
125	sbwdog_pet(user_dog);
126	}
127	clear_bit(0, &sbwdog_gate);
128	expect_close = 0;
129
130	return 0;
131	}
132
133	/*
134	* 42 - the answer
135	*/
136	static ssize_t sbwdog_write(struct file file, const char __user data,
137	size_t len, loff_t *ppos)
138	{
139	int i;
140
141	if (len) {
142	/*
143	* restart the timer
144	*/
145	expect_close = 0;
146
147	for (i = 0; i != len; i++) {
148	char c;
149
150	if (get_user(c, data + i)) {
151	return -EFAULT;
152	}
153	if (c == 'V') {
154	expect_close = 42;
155	}
156	}
157	sbwdog_pet(user_dog);
158	}
159
160	return len;
161	}
162
163	static int sbwdog_ioctl(struct inode inode, struct file file,
164	unsigned int cmd, unsigned long arg)
165	{
166	int ret = -ENOTTY;
167	unsigned long time;
168	void __user argp = (void __user )arg;
169	int __user *p = argp;
170
171	switch (cmd) {
172	case WDIOC_GETSUPPORT:
173	ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
174	break;
175
176	case WDIOC_GETSTATUS:
177	case WDIOC_GETBOOTSTATUS:
178	ret = put_user(0, p);
179	break;
180
181	case WDIOC_SETTIMEOUT:
182	ret = get_user(time, p);
183	if (ret) {
184	break;
185	}
186
187	time *= 1000000;
188	if (time > 0x7fffffUL) {
189	ret = -EINVAL;
190	break;
191	}
192	timeout = time;
193	sbwdog_set(user_dog, timeout);
194	sbwdog_pet(user_dog);
195
196	case WDIOC_GETTIMEOUT:
197	/*
198	* get the remaining count from the ... count register
199	* which is 1*8 before the config register
200	*/
201	ret = put_user(__raw_readq(user_dog - 8) / 1000000, p);
202	break;
203
204	case WDIOC_KEEPALIVE:
205	sbwdog_pet(user_dog);
206	ret = 0;
207	break;
208	}
209	return ret;
210	}
211
212	/*
213	* Notifier for system down
214	*/
215	static int
216	sbwdog_notify_sys(struct notifier_block this, unsigned long code, void erf)
217	{
218	if (code == SYS_DOWN \|\| code == SYS_HALT) {
219	/*
220	* sit and sit
221	*/
222	__raw_writeb(0, user_dog);
223	__raw_writeb(0, kern_dog);
224	}
225
226	return NOTIFY_DONE;
227	}
228
229	static const struct file_operations sbwdog_fops =
230	{
231	.owner = THIS_MODULE,
232	.llseek = no_llseek,
233	.write = sbwdog_write,
234	.ioctl = sbwdog_ioctl,
235	.open = sbwdog_open,
236	.release = sbwdog_release,
237	};
238
239	static struct miscdevice sbwdog_miscdev =
240	{
241	.minor = WATCHDOG_MINOR,
242	.name = "watchdog",
243	.fops = &sbwdog_fops,
244	};
245
246	static struct notifier_block sbwdog_notifier = {
247	.notifier_call = sbwdog_notify_sys,
248	};
249
250	/*
251	* interrupt handler
252	*
253	* doesn't do a whole lot for user, but oh so cleverly written so kernel
254	* code can use it to re-up the watchdog, thereby saving the kernel from
255	* having to create and maintain a timer, just to tickle another timer,
256	* which is just so wrong.
257	*/
258	irqreturn_t sbwdog_interrupt(int irq, void *addr)
259	{
260	unsigned long wd_init;
261	char wd_cfg_reg = (char )addr;
262	u8 cfg;
263
264	cfg = __raw_readb(wd_cfg_reg);
265	wd_init = __raw_readq(wd_cfg_reg - 8) & 0x7fffff;
266
267	/*
268	* if it's the second watchdog timer, it's for those users
269	*/
270	if (wd_cfg_reg == user_dog) {
271	printk(KERN_CRIT
272	"%s in danger of initiating system reset in %ld.%01ld seconds\n",
273	ident.identity, wd_init / 1000000, (wd_init / 100000) % 10);
274	} else {
275	cfg \|= 1;
276	}
277
278	__raw_writeb(cfg, wd_cfg_reg);
279
280	return IRQ_HANDLED;
281	}
282
283	static int __init sbwdog_init(void)
284	{
285	int ret;
286
287	/*
288	* register a reboot notifier
289	*/
290	ret = register_reboot_notifier(&sbwdog_notifier);
291	if (ret) {
292	printk (KERN_ERR "%s: cannot register reboot notifier (err=%d)\n",
293	ident.identity, ret);
294	return ret;
295	}
296
297	/*
298	* get the resources
299	*/
300	ret = misc_register(&sbwdog_miscdev);
301	if (ret == 0) {
302	printk(KERN_INFO "%s: timeout is %ld.%ld secs\n", ident.identity,
303	timeout / 1000000, (timeout / 100000) % 10);
304	}
305
306	ret = request_irq(1, sbwdog_interrupt, IRQF_DISABLED \| IRQF_SHARED,
307	ident.identity, (void *)user_dog);
308	if (ret) {
309	printk(KERN_ERR "%s: failed to request irq 1 - %d\n", ident.identity,
310	ret);
311	misc_deregister(&sbwdog_miscdev);
312	}
313
314	return ret;
315	}
316
317	static void __exit sbwdog_exit(void)
318	{
319	misc_deregister(&sbwdog_miscdev);
320	}
321
322	module_init(sbwdog_init);
323	module_exit(sbwdog_exit);
324
325	MODULE_AUTHOR("Andrew Sharp <andy.sharp@onstor.com>");
326	MODULE_DESCRIPTION("SiByte Watchdog");
327
328	module_param(timeout, ulong, 0);
329	MODULE_PARM_DESC(timeout,
330	"Watchdog timeout in microseconds (max/default 8388607 or 8.3ish secs)");
331
332	MODULE_LICENSE("GPL");
333	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
334
335	/*
336	* example code that can be put in a platform code area to utilize the
337	* first watchdog timer for the kernels own purpose.
338
339	void
340	platform_wd_setup(void)
341	{
342	int ret;
343
344	ret = request_irq(0, sbwdog_interrupt, IRQF_DISABLED \| IRQF_SHARED,
345	"Kernel Watchdog", IOADDR(A_SCD_WDOG_CFG_0));
346	if (ret) {
347	printk(KERN_CRIT "Watchdog IRQ zero(0) failed to be requested - %d\n",
348	ret);
349	}
350	}
351
352
353	*/