[deliverable/linux.git] / drivers / watchdog / sc520_wdt.c

/*
 *	AMD Elan SC520 processor Watchdog Timer driver
 *
 *	Based on acquirewdt.c by Alan Cox,
 *	     and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 *
 *	The authors do NOT admit liability nor provide warranty for
 *	any of this software. This material is provided "AS-IS" in
 *	the hope that it may be useful for others.
 *
 *	(c) Copyright 2001    Scott Jennings <linuxdrivers@oro.net>
 *           9/27 - 2001      [Initial release]
 *
 *	Additional fixes Alan Cox
 *	-	Fixed formatting
 *	-	Removed debug printks
 *	-	Fixed SMP built kernel deadlock
 *	-	Switched to private locks not lock_kernel
 *	-	Used ioremap/writew/readw
 *	-	Added NOWAYOUT support
 *	4/12 - 2002 Changes by Rob Radez <rob@osinvestor.com>
 *	-	Change comments
 *	-	Eliminate fop_llseek
 *	-	Change CONFIG_WATCHDOG_NOWAYOUT semantics
 *	-	Add KERN_* tags to printks
 *	-	fix possible wdt_is_open race
 *	-	Report proper capabilities in watchdog_info
 *	-	Add WDIOC_{GETSTATUS, GETBOOTSTATUS, SETTIMEOUT,
 *		GETTIMEOUT, SETOPTIONS} ioctls
 *	09/8 - 2003 Changes by Wim Van Sebroeck <wim@iguana.be>
 *	-	cleanup of trailing spaces
 *	-	added extra printk's for startup problems
 *	-	use module_param
 *	-	made timeout (the emulated heartbeat) a module_param
 *	-	made the keepalive ping an internal subroutine
 *	3/27 - 2004 Changes by Sean Young <sean@mess.org>
 *	-	set MMCR_BASE to 0xfffef000
 *	-	CBAR does not need to be read
 *	-	removed debugging printks
 *
 *  This WDT driver is different from most other Linux WDT
 *  drivers in that the driver will ping the watchdog by itself,
 *  because this particular WDT has a very short timeout (1.6
 *  seconds) and it would be insane to count on any userspace
 *  daemon always getting scheduled within that time frame.
 *
 *  This driver uses memory mapped IO, and spinlock.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/ioport.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/io.h>
#include <linux/uaccess.h>


/*
 * The AMD Elan SC520 timeout value is 492us times a power of 2 (0-7)
 *
 *   0: 492us    2: 1.01s    4: 4.03s   6: 16.22s
 *   1: 503ms    3: 2.01s    5: 8.05s   7: 32.21s
 *
 * We will program the SC520 watchdog for a timeout of 2.01s.
 * If we reset the watchdog every ~250ms we should be safe.
 */

#define WDT_INTERVAL (HZ/4+1)

/*
 * We must not require too good response from the userspace daemon.
 * Here we require the userspace daemon to send us a heartbeat
 * char to /dev/watchdog every 30 seconds.
 */

#define WATCHDOG_TIMEOUT 30		/* 30 sec default timeout */
/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
static int timeout = WATCHDOG_TIMEOUT;
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout,
	"Watchdog timeout in seconds. (1 <= timeout <= 3600, default="
				__MODULE_STRING(WATCHDOG_TIMEOUT) ")");

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
		"Watchdog cannot be stopped once started (default="
				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

/*
 * AMD Elan SC520 - Watchdog Timer Registers
 */
#define MMCR_BASE	0xfffef000	/* The default base address */
#define OFFS_WDTMRCTL	0xCB0	/* Watchdog Timer Control Register */

/* WDT Control Register bit definitions */
#define WDT_EXP_SEL_01	0x0001	/* [01] Time-out = 496 us (with 33 Mhz clk). */
#define WDT_EXP_SEL_02	0x0002	/* [02] Time-out = 508 ms (with 33 Mhz clk). */
#define WDT_EXP_SEL_03	0x0004	/* [03] Time-out = 1.02 s (with 33 Mhz clk). */
#define WDT_EXP_SEL_04	0x0008	/* [04] Time-out = 2.03 s (with 33 Mhz clk). */
#define WDT_EXP_SEL_05	0x0010	/* [05] Time-out = 4.07 s (with 33 Mhz clk). */
#define WDT_EXP_SEL_06	0x0020	/* [06] Time-out = 8.13 s (with 33 Mhz clk). */
#define WDT_EXP_SEL_07	0x0040	/* [07] Time-out = 16.27s (with 33 Mhz clk). */
#define WDT_EXP_SEL_08	0x0080	/* [08] Time-out = 32.54s (with 33 Mhz clk). */
#define WDT_IRQ_FLG	0x1000	/* [12] Interrupt Request Flag */
#define WDT_WRST_ENB	0x4000	/* [14] Watchdog Timer Reset Enable */
#define WDT_ENB		0x8000	/* [15] Watchdog Timer Enable */

static __u16 __iomem *wdtmrctl;

static void wdt_timer_ping(unsigned long);
static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
static unsigned long next_heartbeat;
static unsigned long wdt_is_open;
static char wdt_expect_close;
static DEFINE_SPINLOCK(wdt_spinlock);

/*
 *	Whack the dog
 */

static void wdt_timer_ping(unsigned long data)
{
	/* If we got a heartbeat pulse within the WDT_US_INTERVAL
	 * we agree to ping the WDT
	 */
	if (time_before(jiffies, next_heartbeat)) {
		/* Ping the WDT */
		spin_lock(&wdt_spinlock);
		writew(0xAAAA, wdtmrctl);
		writew(0x5555, wdtmrctl);
		spin_unlock(&wdt_spinlock);

		/* Re-set the timer interval */
		mod_timer(&timer, jiffies + WDT_INTERVAL);
	} else
		pr_warn("Heartbeat lost! Will not ping the watchdog\n");
}

/*
 *	Utility routines
 */

static void wdt_config(int writeval)
{
	unsigned long flags;

	/* buy some time (ping) */
	spin_lock_irqsave(&wdt_spinlock, flags);
	readw(wdtmrctl);	/* ensure write synchronization */
	writew(0xAAAA, wdtmrctl);
	writew(0x5555, wdtmrctl);
	/* unlock WDT = make WDT configuration register writable one time */
	writew(0x3333, wdtmrctl);
	writew(0xCCCC, wdtmrctl);
	/* write WDT configuration register */
	writew(writeval, wdtmrctl);
	spin_unlock_irqrestore(&wdt_spinlock, flags);
}

static int wdt_startup(void)
{
	next_heartbeat = jiffies + (timeout * HZ);

	/* Start the timer */
	mod_timer(&timer, jiffies + WDT_INTERVAL);

	/* Start the watchdog */
	wdt_config(WDT_ENB | WDT_WRST_ENB | WDT_EXP_SEL_04);

	pr_info("Watchdog timer is now enabled\n");
	return 0;
}

static int wdt_turnoff(void)
{
	/* Stop the timer */
	del_timer(&timer);

	/* Stop the watchdog */
	wdt_config(0);

	pr_info("Watchdog timer is now disabled...\n");
	return 0;
}

static int wdt_keepalive(void)
{
	/* user land ping */
	next_heartbeat = jiffies + (timeout * HZ);
	return 0;
}

static int wdt_set_heartbeat(int t)
{
	if ((t < 1) || (t > 3600))	/* arbitrary upper limit */
		return -EINVAL;

	timeout = t;
	return 0;
}

/*
 *	/dev/watchdog handling
 */

static ssize_t fop_write(struct file *file, const char __user *buf,
						size_t count, loff_t *ppos)
{
	/* See if we got the magic character 'V' and reload the timer */
	if (count) {
		if (!nowayout) {
			size_t ofs;

			/* note: just in case someone wrote the magic character
			 * five months ago... */
			wdt_expect_close = 0;

			/* now scan */
			for (ofs = 0; ofs != count; ofs++) {
				char c;
				if (get_user(c, buf + ofs))
					return -EFAULT;
				if (c == 'V')
					wdt_expect_close = 42;
			}
		}

		/* Well, anyhow someone wrote to us, we should
		   return that favour */
		wdt_keepalive();
	}
	return count;
}

static int fop_open(struct inode *inode, struct file *file)
{
	/* Just in case we're already talking to someone... */
	if (test_and_set_bit(0, &wdt_is_open))
		return -EBUSY;
	if (nowayout)
		__module_get(THIS_MODULE);

	/* Good, fire up the show */
	wdt_startup();
	return nonseekable_open(inode, file);
}

static int fop_close(struct inode *inode, struct file *file)
{
	if (wdt_expect_close == 42)
		wdt_turnoff();
	else {
		pr_crit("Unexpected close, not stopping watchdog!\n");
		wdt_keepalive();
	}
	clear_bit(0, &wdt_is_open);
	wdt_expect_close = 0;
	return 0;
}

static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	void __user *argp = (void __user *)arg;
	int __user *p = argp;
	static const struct watchdog_info ident = {
		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
							| WDIOF_MAGICCLOSE,
		.firmware_version = 1,
		.identity = "SC520",
	};

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
		return put_user(0, p);
	case WDIOC_SETOPTIONS:
	{
		int new_options, retval = -EINVAL;

		if (get_user(new_options, p))
			return -EFAULT;

		if (new_options & WDIOS_DISABLECARD) {
			wdt_turnoff();
			retval = 0;
		}

		if (new_options & WDIOS_ENABLECARD) {
			wdt_startup();
			retval = 0;
		}

		return retval;
	}
	case WDIOC_KEEPALIVE:
		wdt_keepalive();
		return 0;
	case WDIOC_SETTIMEOUT:
	{
		int new_timeout;

		if (get_user(new_timeout, p))
			return -EFAULT;

		if (wdt_set_heartbeat(new_timeout))
			return -EINVAL;

		wdt_keepalive();
		/* Fall through */
	}
	case WDIOC_GETTIMEOUT:
		return put_user(timeout, p);
	default:
		return -ENOTTY;
	}
}

static const struct file_operations wdt_fops = {
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.write		= fop_write,
	.open		= fop_open,
	.release	= fop_close,
	.unlocked_ioctl	= fop_ioctl,
};

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

/*
 *	Notifier for system down
 */

static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
	void *unused)
{
	if (code == SYS_DOWN || code == SYS_HALT)
		wdt_turnoff();
	return NOTIFY_DONE;
}

/*
 *	The WDT needs to learn about soft shutdowns in order to
 *	turn the timebomb registers off.
 */

static struct notifier_block wdt_notifier = {
	.notifier_call = wdt_notify_sys,
};

static void __exit sc520_wdt_unload(void)
{
	if (!nowayout)
		wdt_turnoff();

	/* Deregister */
	misc_deregister(&wdt_miscdev);
	unregister_reboot_notifier(&wdt_notifier);
	iounmap(wdtmrctl);
}

static int __init sc520_wdt_init(void)
{
	int rc = -EBUSY;

	/* Check that the timeout value is within it's range ;
	   if not reset to the default */
	if (wdt_set_heartbeat(timeout)) {
		wdt_set_heartbeat(WATCHDOG_TIMEOUT);
		pr_info("timeout value must be 1 <= timeout <= 3600, using %d\n",
			WATCHDOG_TIMEOUT);
	}

	wdtmrctl = ioremap(MMCR_BASE + OFFS_WDTMRCTL, 2);
	if (!wdtmrctl) {
		pr_err("Unable to remap memory\n");
		rc = -ENOMEM;
		goto err_out_region2;
	}

	rc = register_reboot_notifier(&wdt_notifier);
	if (rc) {
		pr_err("cannot register reboot notifier (err=%d)\n", rc);
		goto err_out_ioremap;
	}

	rc = misc_register(&wdt_miscdev);
	if (rc) {
		pr_err("cannot register miscdev on minor=%d (err=%d)\n",
		       WATCHDOG_MINOR, rc);
		goto err_out_notifier;
	}

	pr_info("WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n",
		timeout, nowayout);

	return 0;

err_out_notifier:
	unregister_reboot_notifier(&wdt_notifier);
err_out_ioremap:
	iounmap(wdtmrctl);
err_out_region2:
	return rc;
}

module_init(sc520_wdt_init);
module_exit(sc520_wdt_unload);

MODULE_AUTHOR("Scott and Bill Jennings");
MODULE_DESCRIPTION(
	"Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor");
MODULE_LICENSE("GPL");
Commit	Line	Data
1da177e4 LT	1	/*
	2	* AMD Elan SC520 processor Watchdog Timer driver
	3	*
143a2e54 WVS	4	* Based on acquirewdt.c by Alan Cox,
143a2e54 WVS	5	* and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
1da177e4 LT	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	* The authors do NOT admit liability nor provide warranty for
	13	* any of this software. This material is provided "AS-IS" in
143a2e54	14	* the hope that it may be useful for others.
1da177e4 LT	15	*
	16	* (c) Copyright 2001 Scott Jennings <linuxdrivers@oro.net>
	17	* 9/27 - 2001 [Initial release]
	18	*
	19	* Additional fixes Alan Cox
	20	* - Fixed formatting
	21	* - Removed debug printks
	22	* - Fixed SMP built kernel deadlock
	23	* - Switched to private locks not lock_kernel
	24	* - Used ioremap/writew/readw
	25	* - Added NOWAYOUT support
	26	* 4/12 - 2002 Changes by Rob Radez <rob@osinvestor.com>
	27	* - Change comments
	28	* - Eliminate fop_llseek
	29	* - Change CONFIG_WATCHDOG_NOWAYOUT semantics
	30	* - Add KERN_* tags to printks
	31	* - fix possible wdt_is_open race
	32	* - Report proper capabilities in watchdog_info
	33	* - Add WDIOC_{GETSTATUS, GETBOOTSTATUS, SETTIMEOUT,
	34	* GETTIMEOUT, SETOPTIONS} ioctls
	35	* 09/8 - 2003 Changes by Wim Van Sebroeck <wim@iguana.be>
	36	* - cleanup of trailing spaces
	37	* - added extra printk's for startup problems
	38	* - use module_param
	39	* - made timeout (the emulated heartbeat) a module_param
	40	* - made the keepalive ping an internal subroutine
	41	* 3/27 - 2004 Changes by Sean Young <sean@mess.org>
	42	* - set MMCR_BASE to 0xfffef000
	43	* - CBAR does not need to be read
	44	* - removed debugging printks
	45	*
	46	* This WDT driver is different from most other Linux WDT
	47	* drivers in that the driver will ping the watchdog by itself,
	48	* because this particular WDT has a very short timeout (1.6
	49	* seconds) and it would be insane to count on any userspace
	50	* daemon always getting scheduled within that time frame.
	51	*
	52	* This driver uses memory mapped IO, and spinlock.
	53	*/
	54
27c766aa JP	55	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
27c766aa JP	56
1da177e4 LT	57	#include <linux/module.h>
	58	#include <linux/moduleparam.h>
	59	#include <linux/types.h>
	60	#include <linux/timer.h>
	61	#include <linux/miscdevice.h>
	62	#include <linux/watchdog.h>
	63	#include <linux/fs.h>
	64	#include <linux/ioport.h>
	65	#include <linux/notifier.h>
	66	#include <linux/reboot.h>
	67	#include <linux/init.h>
4e57b681	68	#include <linux/jiffies.h>
ff948060 AC	69	#include <linux/io.h>
ff948060 AC	70	#include <linux/uaccess.h>
1da177e4	71
1da177e4	72
1da177e4 LT	73	/*
	74	* The AMD Elan SC520 timeout value is 492us times a power of 2 (0-7)
	75	*
	76	* 0: 492us 2: 1.01s 4: 4.03s 6: 16.22s
	77	* 1: 503ms 3: 2.01s 5: 8.05s 7: 32.21s
	78	*
	79	* We will program the SC520 watchdog for a timeout of 2.01s.
	80	* If we reset the watchdog every ~250ms we should be safe.
	81	*/
	82
	83	#define WDT_INTERVAL (HZ/4+1)
	84
	85	/*
	86	* We must not require too good response from the userspace daemon.
	87	* Here we require the userspace daemon to send us a heartbeat
	88	* char to /dev/watchdog every 30 seconds.
	89	*/
	90
	91	#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
ff948060 AC	92	/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
ff948060 AC	93	static int timeout = WATCHDOG_TIMEOUT;
1da177e4	94	module_param(timeout, int, 0);
ff948060 AC	95	MODULE_PARM_DESC(timeout,
	96	"Watchdog timeout in seconds. (1 <= timeout <= 3600, default="
	97	__MODULE_STRING(WATCHDOG_TIMEOUT) ")");
1da177e4	98
86a1e189 WVS	99	static bool nowayout = WATCHDOG_NOWAYOUT;
86a1e189 WVS	100	module_param(nowayout, bool, 0);
ff948060 AC	101	MODULE_PARM_DESC(nowayout,
	102	"Watchdog cannot be stopped once started (default="
	103	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
1da177e4 LT	104
	105	/*
	106	* AMD Elan SC520 - Watchdog Timer Registers
	107	*/
	108	#define MMCR_BASE 0xfffef000 /* The default base address */
	109	#define OFFS_WDTMRCTL 0xCB0 /* Watchdog Timer Control Register */
	110
	111	/* WDT Control Register bit definitions */
	112	#define WDT_EXP_SEL_01 0x0001 /* [01] Time-out = 496 us (with 33 Mhz clk). */
	113	#define WDT_EXP_SEL_02 0x0002 /* [02] Time-out = 508 ms (with 33 Mhz clk). */
	114	#define WDT_EXP_SEL_03 0x0004 /* [03] Time-out = 1.02 s (with 33 Mhz clk). */
	115	#define WDT_EXP_SEL_04 0x0008 /* [04] Time-out = 2.03 s (with 33 Mhz clk). */
	116	#define WDT_EXP_SEL_05 0x0010 /* [05] Time-out = 4.07 s (with 33 Mhz clk). */
	117	#define WDT_EXP_SEL_06 0x0020 /* [06] Time-out = 8.13 s (with 33 Mhz clk). */
	118	#define WDT_EXP_SEL_07 0x0040 /* [07] Time-out = 16.27s (with 33 Mhz clk). */
	119	#define WDT_EXP_SEL_08 0x0080 /* [08] Time-out = 32.54s (with 33 Mhz clk). */
	120	#define WDT_IRQ_FLG 0x1000 /* [12] Interrupt Request Flag */
	121	#define WDT_WRST_ENB 0x4000 /* [14] Watchdog Timer Reset Enable */
	122	#define WDT_ENB 0x8000 /* [15] Watchdog Timer Enable */
	123
	124	static __u16 __iomem *wdtmrctl;
	125
	126	static void wdt_timer_ping(unsigned long);
82eb7c50	127	static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
1da177e4 LT	128	static unsigned long next_heartbeat;
	129	static unsigned long wdt_is_open;
	130	static char wdt_expect_close;
c7dfd0cc	131	static DEFINE_SPINLOCK(wdt_spinlock);
1da177e4 LT	132
	133	/*
	134	* Whack the dog
	135	*/
	136
	137	static void wdt_timer_ping(unsigned long data)
	138	{
	139	/* If we got a heartbeat pulse within the WDT_US_INTERVAL
	140	* we agree to ping the WDT
	141	*/
ff948060	142	if (time_before(jiffies, next_heartbeat)) {
1da177e4 LT	143	/* Ping the WDT */
	144	spin_lock(&wdt_spinlock);
	145	writew(0xAAAA, wdtmrctl);
	146	writew(0x5555, wdtmrctl);
	147	spin_unlock(&wdt_spinlock);
	148
	149	/* Re-set the timer interval */
82eb7c50	150	mod_timer(&timer, jiffies + WDT_INTERVAL);
ff948060	151	} else
27c766aa	152	pr_warn("Heartbeat lost! Will not ping the watchdog\n");
1da177e4 LT	153	}
	154
	155	/*
	156	* Utility routines
	157	*/
	158
	159	static void wdt_config(int writeval)
	160	{
1da177e4 LT	161	unsigned long flags;
	162
	163	/* buy some time (ping) */
	164	spin_lock_irqsave(&wdt_spinlock, flags);
a9ba8376	165	readw(wdtmrctl); /* ensure write synchronization */
1da177e4 LT	166	writew(0xAAAA, wdtmrctl);
	167	writew(0x5555, wdtmrctl);
	168	/* unlock WDT = make WDT configuration register writable one time */
	169	writew(0x3333, wdtmrctl);
	170	writew(0xCCCC, wdtmrctl);
	171	/* write WDT configuration register */
	172	writew(writeval, wdtmrctl);
	173	spin_unlock_irqrestore(&wdt_spinlock, flags);
	174	}
	175
	176	static int wdt_startup(void)
	177	{
	178	next_heartbeat = jiffies + (timeout * HZ);
	179
	180	/* Start the timer */
82eb7c50	181	mod_timer(&timer, jiffies + WDT_INTERVAL);
1da177e4 LT	182
	183	/* Start the watchdog */
	184	wdt_config(WDT_ENB \| WDT_WRST_ENB \| WDT_EXP_SEL_04);
	185
27c766aa	186	pr_info("Watchdog timer is now enabled\n");
1da177e4 LT	187	return 0;
	188	}
	189
	190	static int wdt_turnoff(void)
	191	{
	192	/* Stop the timer */
	193	del_timer(&timer);
	194
	195	/* Stop the watchdog */
	196	wdt_config(0);
	197
27c766aa	198	pr_info("Watchdog timer is now disabled...\n");
1da177e4 LT	199	return 0;
	200	}
	201
	202	static int wdt_keepalive(void)
	203	{
	204	/* user land ping */
	205	next_heartbeat = jiffies + (timeout * HZ);
	206	return 0;
	207	}
	208
	209	static int wdt_set_heartbeat(int t)
	210	{
	211	if ((t < 1) \|\| (t > 3600)) /* arbitrary upper limit */
	212	return -EINVAL;
	213
	214	timeout = t;
	215	return 0;
	216	}
	217
	218	/*
	219	* /dev/watchdog handling
	220	*/
	221
ff948060 AC	222	static ssize_t fop_write(struct file file, const char __user buf,
ff948060 AC	223	size_t count, loff_t *ppos)
1da177e4 LT	224	{
1da177e4 LT	225	/* See if we got the magic character 'V' and reload the timer */
ff948060	226	if (count) {
1da177e4 LT	227	if (!nowayout) {
	228	size_t ofs;
	229
	230	/* note: just in case someone wrote the magic character
	231	* five months ago... */
	232	wdt_expect_close = 0;
	233
	234	/* now scan */
ff948060	235	for (ofs = 0; ofs != count; ofs++) {
1da177e4 LT	236	char c;
	237	if (get_user(c, buf + ofs))
	238	return -EFAULT;
ff948060	239	if (c == 'V')
1da177e4 LT	240	wdt_expect_close = 42;
	241	}
	242	}
	243
ff948060 AC	244	/* Well, anyhow someone wrote to us, we should
ff948060 AC	245	return that favour */
1da177e4 LT	246	wdt_keepalive();
	247	}
	248	return count;
	249	}
	250
ff948060	251	static int fop_open(struct inode inode, struct file file)
1da177e4	252	{
1da177e4	253	/* Just in case we're already talking to someone... */
ff948060	254	if (test_and_set_bit(0, &wdt_is_open))
1da177e4 LT	255	return -EBUSY;
	256	if (nowayout)
	257	__module_get(THIS_MODULE);
	258
	259	/* Good, fire up the show */
	260	wdt_startup();
6abe78bf	261	return nonseekable_open(inode, file);
1da177e4 LT	262	}
1da177e4 LT	263
ff948060	264	static int fop_close(struct inode inode, struct file file)
1da177e4	265	{
ff948060	266	if (wdt_expect_close == 42)
1da177e4	267	wdt_turnoff();
ff948060	268	else {
27c766aa	269	pr_crit("Unexpected close, not stopping watchdog!\n");
1da177e4 LT	270	wdt_keepalive();
	271	}
	272	clear_bit(0, &wdt_is_open);
	273	wdt_expect_close = 0;
	274	return 0;
	275	}
	276
9b748ed0	277	static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1da177e4 LT	278	{
	279	void __user argp = (void __user )arg;
	280	int __user *p = argp;
ff948060 AC	281	static const struct watchdog_info ident = {
	282	.options = WDIOF_KEEPALIVEPING \| WDIOF_SETTIMEOUT
	283	\| WDIOF_MAGICCLOSE,
1da177e4 LT	284	.firmware_version = 1,
	285	.identity = "SC520",
	286	};
	287
5eb82498	288	switch (cmd) {
ff948060 AC	289	case WDIOC_GETSUPPORT:
	290	return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
	291	case WDIOC_GETSTATUS:
	292	case WDIOC_GETBOOTSTATUS:
	293	return put_user(0, p);
ff948060 AC	294	case WDIOC_SETOPTIONS:
	295	{
	296	int new_options, retval = -EINVAL;
1da177e4	297
ff948060 AC	298	if (get_user(new_options, p))
	299	return -EFAULT;
	300
	301	if (new_options & WDIOS_DISABLECARD) {
	302	wdt_turnoff();
	303	retval = 0;
	304	}
1da177e4	305
ff948060 AC	306	if (new_options & WDIOS_ENABLECARD) {
	307	wdt_startup();
	308	retval = 0;
1da177e4	309	}
1da177e4	310
ff948060 AC	311	return retval;
ff948060 AC	312	}
0c06090c WVS	313	case WDIOC_KEEPALIVE:
	314	wdt_keepalive();
	315	return 0;
ff948060 AC	316	case WDIOC_SETTIMEOUT:
	317	{
	318	int new_timeout;
1da177e4	319
ff948060 AC	320	if (get_user(new_timeout, p))
ff948060 AC	321	return -EFAULT;
1da177e4	322
ff948060 AC	323	if (wdt_set_heartbeat(new_timeout))
	324	return -EINVAL;
	325
	326	wdt_keepalive();
	327	/* Fall through */
	328	}
	329	case WDIOC_GETTIMEOUT:
	330	return put_user(timeout, p);
0c06090c WVS	331	default:
0c06090c WVS	332	return -ENOTTY;
1da177e4 LT	333	}
	334	}
	335
62322d25	336	static const struct file_operations wdt_fops = {
1da177e4 LT	337	.owner = THIS_MODULE,
	338	.llseek = no_llseek,
	339	.write = fop_write,
	340	.open = fop_open,
	341	.release = fop_close,
9b748ed0	342	.unlocked_ioctl = fop_ioctl,
1da177e4 LT	343	};
	344
	345	static struct miscdevice wdt_miscdev = {
	346	.minor = WATCHDOG_MINOR,
	347	.name = "watchdog",
	348	.fops = &wdt_fops,
	349	};
	350
	351	/*
	352	* Notifier for system down
	353	*/
	354
	355	static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
	356	void *unused)
	357	{
ff948060	358	if (code == SYS_DOWN \|\| code == SYS_HALT)
1da177e4 LT	359	wdt_turnoff();
	360	return NOTIFY_DONE;
	361	}
	362
	363	/*
	364	* The WDT needs to learn about soft shutdowns in order to
	365	* turn the timebomb registers off.
	366	*/
	367
	368	static struct notifier_block wdt_notifier = {
	369	.notifier_call = wdt_notify_sys,
	370	};
	371
	372	static void __exit sc520_wdt_unload(void)
	373	{
	374	if (!nowayout)
	375	wdt_turnoff();
	376
	377	/* Deregister */
	378	misc_deregister(&wdt_miscdev);
	379	unregister_reboot_notifier(&wdt_notifier);
	380	iounmap(wdtmrctl);
	381	}
	382
	383	static int __init sc520_wdt_init(void)
	384	{
	385	int rc = -EBUSY;
	386
ff948060 AC	387	/* Check that the timeout value is within it's range ;
ff948060 AC	388	if not reset to the default */
1da177e4 LT	389	if (wdt_set_heartbeat(timeout)) {
1da177e4 LT	390	wdt_set_heartbeat(WATCHDOG_TIMEOUT);
27c766aa JP	391	pr_info("timeout value must be 1 <= timeout <= 3600, using %d\n",
27c766aa JP	392	WATCHDOG_TIMEOUT);
1da177e4 LT	393	}
1da177e4 LT	394
cef153a8	395	wdtmrctl = ioremap(MMCR_BASE + OFFS_WDTMRCTL, 2);
1da177e4	396	if (!wdtmrctl) {
27c766aa	397	pr_err("Unable to remap memory\n");
1da177e4 LT	398	rc = -ENOMEM;
	399	goto err_out_region2;
	400	}
	401
	402	rc = register_reboot_notifier(&wdt_notifier);
	403	if (rc) {
27c766aa	404	pr_err("cannot register reboot notifier (err=%d)\n", rc);
1da177e4 LT	405	goto err_out_ioremap;
	406	}
	407
	408	rc = misc_register(&wdt_miscdev);
	409	if (rc) {
27c766aa JP	410	pr_err("cannot register miscdev on minor=%d (err=%d)\n",
27c766aa JP	411	WATCHDOG_MINOR, rc);
1da177e4 LT	412	goto err_out_notifier;
	413	}
	414
27c766aa JP	415	pr_info("WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n",
27c766aa JP	416	timeout, nowayout);
1da177e4 LT	417
	418	return 0;
	419
	420	err_out_notifier:
	421	unregister_reboot_notifier(&wdt_notifier);
	422	err_out_ioremap:
	423	iounmap(wdtmrctl);
	424	err_out_region2:
	425	return rc;
	426	}
	427
	428	module_init(sc520_wdt_init);
	429	module_exit(sc520_wdt_unload);
	430
	431	MODULE_AUTHOR("Scott and Bill Jennings");
143a2e54 WVS	432	MODULE_DESCRIPTION(
143a2e54 WVS	433	"Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor");
1da177e4	434	MODULE_LICENSE("GPL");