[linux.git] / drivers / watchdog / sb_wdog.c

/*
 * Watchdog driver for SiByte SB1 SoCs
 *
 * Copyright (C) 2007 OnStor, Inc. * Andrew Sharp <[email protected]>
 *
 * 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 <[email protected]>,
 *						All Rights Reserved.
 *
 *	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.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#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>

static DEFINE_SPINLOCK(sbwd_lock);

/*
 * 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)
{
	spin_lock(&sbwd_lock);
	__raw_writeb(0, wdog);
	__raw_writeq(t & 0x7fffffUL, wdog - 0x10);
	spin_unlock(&sbwd_lock);
}

/*
 * 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)
{
	spin_lock(&sbwd_lock);
	__raw_writeb(__raw_readb(wdog) | 1, wdog);
	spin_unlock(&sbwd_lock);
}

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 const struct watchdog_info ident = {
	.options	= WDIOF_CARDRESET | WDIOF_SETTIMEOUT |
					WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
	.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 {
		pr_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 long sbwdog_ioctl(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_KEEPALIVE:
		sbwdog_pet(user_dog);
		ret = 0;
		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((u32)__raw_readq(user_dog - 8) / 1000000, p);
		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,
	.unlocked_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)
		pr_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) {
		pr_err("%s: cannot register reboot notifier (err=%d)\n",
		       ident.identity, ret);
		return ret;
	}

	/*
	 * get the resources
	 */

	ret = request_irq(1, sbwdog_interrupt, IRQF_SHARED,
		ident.identity, (void *)user_dog);
	if (ret) {
		pr_err("%s: failed to request irq 1 - %d\n",
		       ident.identity, ret);
		goto out;
	}

	ret = misc_register(&sbwdog_miscdev);
	if (ret == 0) {
		pr_info("%s: timeout is %ld.%ld secs\n",
			ident.identity,
			timeout / 1000000, (timeout / 100000) % 10);
		return 0;
	}
	free_irq(1, (void *)user_dog);
out:
	unregister_reboot_notifier(&sbwdog_notifier);

	return ret;
}

static void __exit sbwdog_exit(void)
{
	misc_deregister(&sbwdog_miscdev);
	free_irq(1, (void *)user_dog);
	unregister_reboot_notifier(&sbwdog_notifier);
}

module_init(sbwdog_init);
module_exit(sbwdog_exit);

MODULE_AUTHOR("Andrew Sharp <[email protected]>");
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");

/*
 * 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(1, sbwdog_interrupt, IRQF_SHARED,
		"Kernel Watchdog", IOADDR(A_SCD_WDOG_CFG_0));
	if (ret) {
		pr_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	*
5b73a41c	4	* Copyright (C) 2007 OnStor, Inc. * Andrew Sharp <[email protected]>
75c752e6 AS	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	*
29fa0586 AC	38	* (c) Copyright 1996 Alan Cox <[email protected]>,
29fa0586 AC	39	* All Rights Reserved.
75c752e6 AS	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	*/
27c766aa JP	46
	47	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
	48
75c752e6 AS	49	#include <linux/module.h>
	50	#include <linux/io.h>
	51	#include <linux/uaccess.h>
	52	#include <linux/fs.h>
	53	#include <linux/reboot.h>
	54	#include <linux/miscdevice.h>
	55	#include <linux/watchdog.h>
	56	#include <linux/interrupt.h>
	57
	58	#include <asm/sibyte/sb1250.h>
	59	#include <asm/sibyte/sb1250_regs.h>
	60	#include <asm/sibyte/sb1250_int.h>
	61	#include <asm/sibyte/sb1250_scd.h>
	62
df3c9de3	63	static DEFINE_SPINLOCK(sbwd_lock);
75c752e6 AS	64
	65	/*
	66	* set the initial count value of a timer
	67	*
	68	* wdog is the iomem address of the cfg register
	69	*/
	70	void sbwdog_set(char __iomem *wdog, unsigned long t)
	71	{
df3c9de3	72	spin_lock(&sbwd_lock);
86913315 GR	73	__raw_writeb(0, wdog);
86913315 GR	74	__raw_writeq(t & 0x7fffffUL, wdog - 0x10);
df3c9de3	75	spin_unlock(&sbwd_lock);
75c752e6 AS	76	}
	77
	78	/*
	79	* cause the timer to [re]load it's initial count and start counting
	80	* all over again
	81	*
	82	* wdog is the iomem address of the cfg register
	83	*/
	84	void sbwdog_pet(char __iomem *wdog)
	85	{
df3c9de3	86	spin_lock(&sbwd_lock);
75c752e6	87	__raw_writeb(__raw_readb(wdog) \| 1, wdog);
df3c9de3	88	spin_unlock(&sbwd_lock);
75c752e6 AS	89	}
	90
	91	static unsigned long sbwdog_gate; /* keeps it to one thread only */
	92	static char __iomem kern_dog = (char __iomem )(IO_BASE + (A_SCD_WDOG_CFG_0));
	93	static char __iomem user_dog = (char __iomem )(IO_BASE + (A_SCD_WDOG_CFG_1));
	94	static unsigned long timeout = 0x7fffffUL; /* useconds: 8.3ish secs. */
	95	static int expect_close;
	96
df3c9de3 AC	97	static const struct watchdog_info ident = {
df3c9de3 AC	98	.options = WDIOF_CARDRESET \| WDIOF_SETTIMEOUT \|
e73a7802	99	WDIOF_KEEPALIVEPING \| WDIOF_MAGICCLOSE,
75c752e6 AS	100	.identity = "SiByte Watchdog",
	101	};
	102
	103	/*
	104	* Allow only a single thread to walk the dog
	105	*/
	106	static int sbwdog_open(struct inode inode, struct file file)
	107	{
	108	nonseekable_open(inode, file);
df3c9de3	109	if (test_and_set_bit(0, &sbwdog_gate))
75c752e6	110	return -EBUSY;
75c752e6 AS	111	__module_get(THIS_MODULE);
	112
	113	/*
	114	* Activate the timer
	115	*/
	116	sbwdog_set(user_dog, timeout);
	117	__raw_writeb(1, user_dog);
	118
	119	return 0;
	120	}
	121
	122	/*
	123	* Put the dog back in the kennel.
	124	*/
	125	static int sbwdog_release(struct inode inode, struct file file)
	126	{
	127	if (expect_close == 42) {
	128	__raw_writeb(0, user_dog);
	129	module_put(THIS_MODULE);
	130	} else {
27c766aa JP	131	pr_crit("%s: Unexpected close, not stopping watchdog!\n",
27c766aa JP	132	ident.identity);
75c752e6 AS	133	sbwdog_pet(user_dog);
	134	}
	135	clear_bit(0, &sbwdog_gate);
	136	expect_close = 0;
	137
	138	return 0;
	139	}
	140
	141	/*
	142	* 42 - the answer
	143	*/
	144	static ssize_t sbwdog_write(struct file file, const char __user data,
	145	size_t len, loff_t *ppos)
	146	{
	147	int i;
	148
	149	if (len) {
	150	/*
	151	* restart the timer
	152	*/
	153	expect_close = 0;
	154
	155	for (i = 0; i != len; i++) {
	156	char c;
	157
df3c9de3	158	if (get_user(c, data + i))
75c752e6	159	return -EFAULT;
df3c9de3	160	if (c == 'V')
75c752e6	161	expect_close = 42;
75c752e6 AS	162	}
	163	sbwdog_pet(user_dog);
	164	}
	165
	166	return len;
	167	}
	168
df3c9de3 AC	169	static long sbwdog_ioctl(struct file *file, unsigned int cmd,
df3c9de3 AC	170	unsigned long arg)
75c752e6 AS	171	{
	172	int ret = -ENOTTY;
	173	unsigned long time;
	174	void __user argp = (void __user )arg;
	175	int __user *p = argp;
	176
	177	switch (cmd) {
	178	case WDIOC_GETSUPPORT:
	179	ret = copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
	180	break;
	181
	182	case WDIOC_GETSTATUS:
	183	case WDIOC_GETBOOTSTATUS:
	184	ret = put_user(0, p);
	185	break;
	186
0c06090c WVS	187	case WDIOC_KEEPALIVE:
	188	sbwdog_pet(user_dog);
	189	ret = 0;
	190	break;
	191
75c752e6 AS	192	case WDIOC_SETTIMEOUT:
75c752e6 AS	193	ret = get_user(time, p);
df3c9de3	194	if (ret)
75c752e6	195	break;
75c752e6 AS	196
	197	time *= 1000000;
	198	if (time > 0x7fffffUL) {
	199	ret = -EINVAL;
	200	break;
	201	}
	202	timeout = time;
	203	sbwdog_set(user_dog, timeout);
	204	sbwdog_pet(user_dog);
	205
	206	case WDIOC_GETTIMEOUT:
	207	/*
	208	* get the remaining count from the ... count register
	209	* which is 1*8 before the config register
	210	*/
cd6cbde6	211	ret = put_user((u32)__raw_readq(user_dog - 8) / 1000000, p);
75c752e6	212	break;
75c752e6 AS	213	}
	214	return ret;
	215	}
	216
	217	/*
	218	* Notifier for system down
	219	*/
7944d3a5 WVS	220	static int sbwdog_notify_sys(struct notifier_block *this, unsigned long code,
7944d3a5 WVS	221	void *erf)
75c752e6 AS	222	{
	223	if (code == SYS_DOWN \|\| code == SYS_HALT) {
	224	/*
	225	* sit and sit
	226	*/
	227	__raw_writeb(0, user_dog);
	228	__raw_writeb(0, kern_dog);
	229	}
	230
	231	return NOTIFY_DONE;
	232	}
	233
df3c9de3	234	static const struct file_operations sbwdog_fops = {
75c752e6 AS	235	.owner = THIS_MODULE,
	236	.llseek = no_llseek,
	237	.write = sbwdog_write,
df3c9de3	238	.unlocked_ioctl = sbwdog_ioctl,
75c752e6 AS	239	.open = sbwdog_open,
	240	.release = sbwdog_release,
	241	};
	242
df3c9de3	243	static struct miscdevice sbwdog_miscdev = {
75c752e6 AS	244	.minor = WATCHDOG_MINOR,
	245	.name = "watchdog",
	246	.fops = &sbwdog_fops,
	247	};
	248
	249	static struct notifier_block sbwdog_notifier = {
	250	.notifier_call = sbwdog_notify_sys,
	251	};
	252
	253	/*
	254	* interrupt handler
	255	*
	256	* doesn't do a whole lot for user, but oh so cleverly written so kernel
	257	* code can use it to re-up the watchdog, thereby saving the kernel from
	258	* having to create and maintain a timer, just to tickle another timer,
	259	* which is just so wrong.
	260	*/
	261	irqreturn_t sbwdog_interrupt(int irq, void *addr)
	262	{
	263	unsigned long wd_init;
	264	char wd_cfg_reg = (char )addr;
	265	u8 cfg;
	266
	267	cfg = __raw_readb(wd_cfg_reg);
	268	wd_init = __raw_readq(wd_cfg_reg - 8) & 0x7fffff;
	269
	270	/*
	271	* if it's the second watchdog timer, it's for those users
	272	*/
df3c9de3	273	if (wd_cfg_reg == user_dog)
27c766aa	274	pr_crit("%s in danger of initiating system reset "
a77dba7e WVS	275	"in %ld.%01ld seconds\n",
	276	ident.identity,
	277	wd_init / 1000000, (wd_init / 100000) % 10);
df3c9de3	278	else
75c752e6	279	cfg \|= 1;
75c752e6 AS	280
	281	__raw_writeb(cfg, wd_cfg_reg);
	282
	283	return IRQ_HANDLED;
	284	}
	285
	286	static int __init sbwdog_init(void)
	287	{
	288	int ret;
	289
	290	/*
	291	* register a reboot notifier
	292	*/
	293	ret = register_reboot_notifier(&sbwdog_notifier);
	294	if (ret) {
27c766aa JP	295	pr_err("%s: cannot register reboot notifier (err=%d)\n",
27c766aa JP	296	ident.identity, ret);
75c752e6 AS	297	return ret;
	298	}
	299
	300	/*
	301	* get the resources
	302	*/
75c752e6	303
86b59128	304	ret = request_irq(1, sbwdog_interrupt, IRQF_SHARED,
75c752e6 AS	305	ident.identity, (void *)user_dog);
75c752e6 AS	306	if (ret) {
27c766aa JP	307	pr_err("%s: failed to request irq 1 - %d\n",
27c766aa JP	308	ident.identity, ret);
ae44855a	309	goto out;
75c752e6 AS	310	}
75c752e6 AS	311
df3c9de3 AC	312	ret = misc_register(&sbwdog_miscdev);
df3c9de3 AC	313	if (ret == 0) {
27c766aa JP	314	pr_info("%s: timeout is %ld.%ld secs\n",
	315	ident.identity,
	316	timeout / 1000000, (timeout / 100000) % 10);
ae44855a AM	317	return 0;
	318	}
	319	free_irq(1, (void *)user_dog);
	320	out:
	321	unregister_reboot_notifier(&sbwdog_notifier);
	322
75c752e6 AS	323	return ret;
	324	}
	325
	326	static void __exit sbwdog_exit(void)
	327	{
	328	misc_deregister(&sbwdog_miscdev);
ae44855a AM	329	free_irq(1, (void *)user_dog);
ae44855a AM	330	unregister_reboot_notifier(&sbwdog_notifier);
75c752e6 AS	331	}
	332
	333	module_init(sbwdog_init);
	334	module_exit(sbwdog_exit);
	335
5b73a41c	336	MODULE_AUTHOR("Andrew Sharp <[email protected]>");
75c752e6 AS	337	MODULE_DESCRIPTION("SiByte Watchdog");
	338
	339	module_param(timeout, ulong, 0);
	340	MODULE_PARM_DESC(timeout,
df3c9de3	341	"Watchdog timeout in microseconds (max/default 8388607 or 8.3ish secs)");
75c752e6 AS	342
75c752e6 AS	343	MODULE_LICENSE("GPL");
75c752e6 AS	344
	345	/*
	346	* example code that can be put in a platform code area to utilize the
	347	* first watchdog timer for the kernels own purpose.
	348
df3c9de3	349	void platform_wd_setup(void)
75c752e6 AS	350	{
	351	int ret;
	352
86b59128	353	ret = request_irq(1, sbwdog_interrupt, IRQF_SHARED,
75c752e6 AS	354	"Kernel Watchdog", IOADDR(A_SCD_WDOG_CFG_0));
75c752e6 AS	355	if (ret) {
27c766aa	356	pr_crit("Watchdog IRQ zero(0) failed to be requested - %d\n", ret);
75c752e6 AS	357	}
	358	}
	359
	360
	361	*/