[linux-2.6-block.git] / drivers / watchdog / sc520_wdt.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *	AMD Elan SC520 processor Watchdog Timer driver
 *
 *	Based on acquirewdt.c by Alan Cox,
 *	     and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
 *
 *	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(struct timer_list *);
static DEFINE_TIMER(timer, wdt_timer_ping);
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(struct timer_list *unused)
{
	/* 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 stream_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
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
1da177e4 LT	2	/*
	3	* AMD Elan SC520 processor Watchdog Timer driver
	4	*
143a2e54 WVS	5	* Based on acquirewdt.c by Alan Cox,
143a2e54 WVS	6	* and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
1da177e4	7	*
1da177e4 LT	8	* The authors do NOT admit liability nor provide warranty for
1da177e4 LT	9	* any of this software. This material is provided "AS-IS" in
143a2e54	10	* the hope that it may be useful for others.
1da177e4 LT	11	*
	12	* (c) Copyright 2001 Scott Jennings <linuxdrivers@oro.net>
	13	* 9/27 - 2001 [Initial release]
	14	*
	15	* Additional fixes Alan Cox
	16	* - Fixed formatting
	17	* - Removed debug printks
	18	* - Fixed SMP built kernel deadlock
	19	* - Switched to private locks not lock_kernel
	20	* - Used ioremap/writew/readw
	21	* - Added NOWAYOUT support
	22	* 4/12 - 2002 Changes by Rob Radez <rob@osinvestor.com>
	23	* - Change comments
	24	* - Eliminate fop_llseek
	25	* - Change CONFIG_WATCHDOG_NOWAYOUT semantics
	26	* - Add KERN_* tags to printks
	27	* - fix possible wdt_is_open race
	28	* - Report proper capabilities in watchdog_info
	29	* - Add WDIOC_{GETSTATUS, GETBOOTSTATUS, SETTIMEOUT,
	30	* GETTIMEOUT, SETOPTIONS} ioctls
	31	* 09/8 - 2003 Changes by Wim Van Sebroeck <wim@iguana.be>
	32	* - cleanup of trailing spaces
	33	* - added extra printk's for startup problems
	34	* - use module_param
	35	* - made timeout (the emulated heartbeat) a module_param
	36	* - made the keepalive ping an internal subroutine
	37	* 3/27 - 2004 Changes by Sean Young <sean@mess.org>
	38	* - set MMCR_BASE to 0xfffef000
	39	* - CBAR does not need to be read
	40	* - removed debugging printks
	41	*
	42	* This WDT driver is different from most other Linux WDT
	43	* drivers in that the driver will ping the watchdog by itself,
	44	* because this particular WDT has a very short timeout (1.6
	45	* seconds) and it would be insane to count on any userspace
	46	* daemon always getting scheduled within that time frame.
	47	*
	48	* This driver uses memory mapped IO, and spinlock.
	49	*/
	50
27c766aa JP	51	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
27c766aa JP	52
1da177e4 LT	53	#include <linux/module.h>
	54	#include <linux/moduleparam.h>
	55	#include <linux/types.h>
	56	#include <linux/timer.h>
	57	#include <linux/miscdevice.h>
	58	#include <linux/watchdog.h>
	59	#include <linux/fs.h>
	60	#include <linux/ioport.h>
	61	#include <linux/notifier.h>
	62	#include <linux/reboot.h>
	63	#include <linux/init.h>
4e57b681	64	#include <linux/jiffies.h>
ff948060 AC	65	#include <linux/io.h>
ff948060 AC	66	#include <linux/uaccess.h>
1da177e4	67
1da177e4	68
1da177e4 LT	69	/*
	70	* The AMD Elan SC520 timeout value is 492us times a power of 2 (0-7)
	71	*
	72	* 0: 492us 2: 1.01s 4: 4.03s 6: 16.22s
	73	* 1: 503ms 3: 2.01s 5: 8.05s 7: 32.21s
	74	*
	75	* We will program the SC520 watchdog for a timeout of 2.01s.
	76	* If we reset the watchdog every ~250ms we should be safe.
	77	*/
	78
	79	#define WDT_INTERVAL (HZ/4+1)
	80
	81	/*
	82	* We must not require too good response from the userspace daemon.
	83	* Here we require the userspace daemon to send us a heartbeat
	84	* char to /dev/watchdog every 30 seconds.
	85	*/
	86
	87	#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
ff948060 AC	88	/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
ff948060 AC	89	static int timeout = WATCHDOG_TIMEOUT;
1da177e4	90	module_param(timeout, int, 0);
ff948060 AC	91	MODULE_PARM_DESC(timeout,
	92	"Watchdog timeout in seconds. (1 <= timeout <= 3600, default="
	93	__MODULE_STRING(WATCHDOG_TIMEOUT) ")");
1da177e4	94
86a1e189 WVS	95	static bool nowayout = WATCHDOG_NOWAYOUT;
86a1e189 WVS	96	module_param(nowayout, bool, 0);
ff948060 AC	97	MODULE_PARM_DESC(nowayout,
	98	"Watchdog cannot be stopped once started (default="
	99	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
1da177e4 LT	100
	101	/*
	102	* AMD Elan SC520 - Watchdog Timer Registers
	103	*/
	104	#define MMCR_BASE 0xfffef000 /* The default base address */
	105	#define OFFS_WDTMRCTL 0xCB0 /* Watchdog Timer Control Register */
	106
	107	/* WDT Control Register bit definitions */
	108	#define WDT_EXP_SEL_01 0x0001 /* [01] Time-out = 496 us (with 33 Mhz clk). */
	109	#define WDT_EXP_SEL_02 0x0002 /* [02] Time-out = 508 ms (with 33 Mhz clk). */
	110	#define WDT_EXP_SEL_03 0x0004 /* [03] Time-out = 1.02 s (with 33 Mhz clk). */
	111	#define WDT_EXP_SEL_04 0x0008 /* [04] Time-out = 2.03 s (with 33 Mhz clk). */
	112	#define WDT_EXP_SEL_05 0x0010 /* [05] Time-out = 4.07 s (with 33 Mhz clk). */
	113	#define WDT_EXP_SEL_06 0x0020 /* [06] Time-out = 8.13 s (with 33 Mhz clk). */
	114	#define WDT_EXP_SEL_07 0x0040 /* [07] Time-out = 16.27s (with 33 Mhz clk). */
	115	#define WDT_EXP_SEL_08 0x0080 /* [08] Time-out = 32.54s (with 33 Mhz clk). */
	116	#define WDT_IRQ_FLG 0x1000 /* [12] Interrupt Request Flag */
	117	#define WDT_WRST_ENB 0x4000 /* [14] Watchdog Timer Reset Enable */
	118	#define WDT_ENB 0x8000 /* [15] Watchdog Timer Enable */
	119
	120	static __u16 __iomem *wdtmrctl;
	121
24ed960a	122	static void wdt_timer_ping(struct timer_list *);
1d27e3e2	123	static DEFINE_TIMER(timer, wdt_timer_ping);
1da177e4 LT	124	static unsigned long next_heartbeat;
	125	static unsigned long wdt_is_open;
	126	static char wdt_expect_close;
c7dfd0cc	127	static DEFINE_SPINLOCK(wdt_spinlock);
1da177e4 LT	128
	129	/*
	130	* Whack the dog
	131	*/
	132
24ed960a	133	static void wdt_timer_ping(struct timer_list *unused)
1da177e4 LT	134	{
	135	/* If we got a heartbeat pulse within the WDT_US_INTERVAL
	136	* we agree to ping the WDT
	137	*/
ff948060	138	if (time_before(jiffies, next_heartbeat)) {
1da177e4 LT	139	/* Ping the WDT */
	140	spin_lock(&wdt_spinlock);
	141	writew(0xAAAA, wdtmrctl);
	142	writew(0x5555, wdtmrctl);
	143	spin_unlock(&wdt_spinlock);
	144
	145	/* Re-set the timer interval */
82eb7c50	146	mod_timer(&timer, jiffies + WDT_INTERVAL);
ff948060	147	} else
27c766aa	148	pr_warn("Heartbeat lost! Will not ping the watchdog\n");
1da177e4 LT	149	}
	150
	151	/*
	152	* Utility routines
	153	*/
	154
	155	static void wdt_config(int writeval)
	156	{
1da177e4 LT	157	unsigned long flags;
	158
	159	/* buy some time (ping) */
	160	spin_lock_irqsave(&wdt_spinlock, flags);
a9ba8376	161	readw(wdtmrctl); /* ensure write synchronization */
1da177e4 LT	162	writew(0xAAAA, wdtmrctl);
	163	writew(0x5555, wdtmrctl);
	164	/* unlock WDT = make WDT configuration register writable one time */
	165	writew(0x3333, wdtmrctl);
	166	writew(0xCCCC, wdtmrctl);
	167	/* write WDT configuration register */
	168	writew(writeval, wdtmrctl);
	169	spin_unlock_irqrestore(&wdt_spinlock, flags);
	170	}
	171
	172	static int wdt_startup(void)
	173	{
	174	next_heartbeat = jiffies + (timeout * HZ);
	175
	176	/* Start the timer */
82eb7c50	177	mod_timer(&timer, jiffies + WDT_INTERVAL);
1da177e4 LT	178
	179	/* Start the watchdog */
	180	wdt_config(WDT_ENB \| WDT_WRST_ENB \| WDT_EXP_SEL_04);
	181
27c766aa	182	pr_info("Watchdog timer is now enabled\n");
1da177e4 LT	183	return 0;
	184	}
	185
	186	static int wdt_turnoff(void)
	187	{
	188	/* Stop the timer */
	189	del_timer(&timer);
	190
	191	/* Stop the watchdog */
	192	wdt_config(0);
	193
27c766aa	194	pr_info("Watchdog timer is now disabled...\n");
1da177e4 LT	195	return 0;
	196	}
	197
	198	static int wdt_keepalive(void)
	199	{
	200	/* user land ping */
	201	next_heartbeat = jiffies + (timeout * HZ);
	202	return 0;
	203	}
	204
	205	static int wdt_set_heartbeat(int t)
	206	{
	207	if ((t < 1) \|\| (t > 3600)) /* arbitrary upper limit */
	208	return -EINVAL;
	209
	210	timeout = t;
	211	return 0;
	212	}
	213
	214	/*
	215	* /dev/watchdog handling
	216	*/
	217
ff948060 AC	218	static ssize_t fop_write(struct file file, const char __user buf,
ff948060 AC	219	size_t count, loff_t *ppos)
1da177e4 LT	220	{
1da177e4 LT	221	/* See if we got the magic character 'V' and reload the timer */
ff948060	222	if (count) {
1da177e4 LT	223	if (!nowayout) {
	224	size_t ofs;
	225
	226	/* note: just in case someone wrote the magic character
	227	* five months ago... */
	228	wdt_expect_close = 0;
	229
	230	/* now scan */
ff948060	231	for (ofs = 0; ofs != count; ofs++) {
1da177e4 LT	232	char c;
	233	if (get_user(c, buf + ofs))
	234	return -EFAULT;
ff948060	235	if (c == 'V')
1da177e4 LT	236	wdt_expect_close = 42;
	237	}
	238	}
	239
ff948060 AC	240	/* Well, anyhow someone wrote to us, we should
ff948060 AC	241	return that favour */
1da177e4 LT	242	wdt_keepalive();
	243	}
	244	return count;
	245	}
	246
ff948060	247	static int fop_open(struct inode inode, struct file file)
1da177e4	248	{
1da177e4	249	/* Just in case we're already talking to someone... */
ff948060	250	if (test_and_set_bit(0, &wdt_is_open))
1da177e4 LT	251	return -EBUSY;
	252	if (nowayout)
	253	__module_get(THIS_MODULE);
	254
	255	/* Good, fire up the show */
	256	wdt_startup();
c5bf68fe	257	return stream_open(inode, file);
1da177e4 LT	258	}
1da177e4 LT	259
ff948060	260	static int fop_close(struct inode inode, struct file file)
1da177e4	261	{
ff948060	262	if (wdt_expect_close == 42)
1da177e4	263	wdt_turnoff();
ff948060	264	else {
27c766aa	265	pr_crit("Unexpected close, not stopping watchdog!\n");
1da177e4 LT	266	wdt_keepalive();
	267	}
	268	clear_bit(0, &wdt_is_open);
	269	wdt_expect_close = 0;
	270	return 0;
	271	}
	272
9b748ed0	273	static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1da177e4 LT	274	{
	275	void __user argp = (void __user )arg;
	276	int __user *p = argp;
ff948060 AC	277	static const struct watchdog_info ident = {
	278	.options = WDIOF_KEEPALIVEPING \| WDIOF_SETTIMEOUT
	279	\| WDIOF_MAGICCLOSE,
1da177e4 LT	280	.firmware_version = 1,
	281	.identity = "SC520",
	282	};
	283
5eb82498	284	switch (cmd) {
ff948060 AC	285	case WDIOC_GETSUPPORT:
	286	return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
	287	case WDIOC_GETSTATUS:
	288	case WDIOC_GETBOOTSTATUS:
	289	return put_user(0, p);
ff948060 AC	290	case WDIOC_SETOPTIONS:
	291	{
	292	int new_options, retval = -EINVAL;
1da177e4	293
ff948060 AC	294	if (get_user(new_options, p))
	295	return -EFAULT;
	296
	297	if (new_options & WDIOS_DISABLECARD) {
	298	wdt_turnoff();
	299	retval = 0;
	300	}
1da177e4	301
ff948060 AC	302	if (new_options & WDIOS_ENABLECARD) {
	303	wdt_startup();
	304	retval = 0;
1da177e4	305	}
1da177e4	306
ff948060 AC	307	return retval;
ff948060 AC	308	}
0c06090c WVS	309	case WDIOC_KEEPALIVE:
	310	wdt_keepalive();
	311	return 0;
ff948060 AC	312	case WDIOC_SETTIMEOUT:
	313	{
	314	int new_timeout;
1da177e4	315
ff948060 AC	316	if (get_user(new_timeout, p))
ff948060 AC	317	return -EFAULT;
1da177e4	318
ff948060 AC	319	if (wdt_set_heartbeat(new_timeout))
	320	return -EINVAL;
	321
	322	wdt_keepalive();
ff948060	323	}
e70d3547	324	/* Fall through */
ff948060 AC	325	case WDIOC_GETTIMEOUT:
ff948060 AC	326	return put_user(timeout, p);
0c06090c WVS	327	default:
0c06090c WVS	328	return -ENOTTY;
1da177e4 LT	329	}
	330	}
	331
62322d25	332	static const struct file_operations wdt_fops = {
1da177e4 LT	333	.owner = THIS_MODULE,
	334	.llseek = no_llseek,
	335	.write = fop_write,
	336	.open = fop_open,
	337	.release = fop_close,
9b748ed0	338	.unlocked_ioctl = fop_ioctl,
1da177e4 LT	339	};
	340
	341	static struct miscdevice wdt_miscdev = {
	342	.minor = WATCHDOG_MINOR,
	343	.name = "watchdog",
	344	.fops = &wdt_fops,
	345	};
	346
	347	/*
	348	* Notifier for system down
	349	*/
	350
	351	static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
	352	void *unused)
	353	{
ff948060	354	if (code == SYS_DOWN \|\| code == SYS_HALT)
1da177e4 LT	355	wdt_turnoff();
	356	return NOTIFY_DONE;
	357	}
	358
	359	/*
	360	* The WDT needs to learn about soft shutdowns in order to
	361	* turn the timebomb registers off.
	362	*/
	363
	364	static struct notifier_block wdt_notifier = {
	365	.notifier_call = wdt_notify_sys,
	366	};
	367
	368	static void __exit sc520_wdt_unload(void)
	369	{
	370	if (!nowayout)
	371	wdt_turnoff();
	372
	373	/* Deregister */
	374	misc_deregister(&wdt_miscdev);
	375	unregister_reboot_notifier(&wdt_notifier);
	376	iounmap(wdtmrctl);
	377	}
	378
	379	static int __init sc520_wdt_init(void)
	380	{
	381	int rc = -EBUSY;
	382
ff948060 AC	383	/* Check that the timeout value is within it's range ;
ff948060 AC	384	if not reset to the default */
1da177e4 LT	385	if (wdt_set_heartbeat(timeout)) {
1da177e4 LT	386	wdt_set_heartbeat(WATCHDOG_TIMEOUT);
27c766aa JP	387	pr_info("timeout value must be 1 <= timeout <= 3600, using %d\n",
27c766aa JP	388	WATCHDOG_TIMEOUT);
1da177e4 LT	389	}
1da177e4 LT	390
cef153a8	391	wdtmrctl = ioremap(MMCR_BASE + OFFS_WDTMRCTL, 2);
1da177e4	392	if (!wdtmrctl) {
27c766aa	393	pr_err("Unable to remap memory\n");
1da177e4 LT	394	rc = -ENOMEM;
	395	goto err_out_region2;
	396	}
	397
	398	rc = register_reboot_notifier(&wdt_notifier);
	399	if (rc) {
27c766aa	400	pr_err("cannot register reboot notifier (err=%d)\n", rc);
1da177e4 LT	401	goto err_out_ioremap;
	402	}
	403
	404	rc = misc_register(&wdt_miscdev);
	405	if (rc) {
27c766aa JP	406	pr_err("cannot register miscdev on minor=%d (err=%d)\n",
27c766aa JP	407	WATCHDOG_MINOR, rc);
1da177e4 LT	408	goto err_out_notifier;
	409	}
	410
27c766aa JP	411	pr_info("WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n",
27c766aa JP	412	timeout, nowayout);
1da177e4 LT	413
	414	return 0;
	415
	416	err_out_notifier:
	417	unregister_reboot_notifier(&wdt_notifier);
	418	err_out_ioremap:
	419	iounmap(wdtmrctl);
	420	err_out_region2:
	421	return rc;
	422	}
	423
	424	module_init(sc520_wdt_init);
	425	module_exit(sc520_wdt_unload);
	426
	427	MODULE_AUTHOR("Scott and Bill Jennings");
143a2e54 WVS	428	MODULE_DESCRIPTION(
143a2e54 WVS	429	"Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor");
1da177e4	430	MODULE_LICENSE("GPL");