[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 <[email protected]>
 *
 *	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 <[email protected]>
 *           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 <[email protected]>
 *	-	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 <[email protected]>
 *	-	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 <[email protected]>
 *	-	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.
 */

#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>

#include <asm/system.h>

#define OUR_NAME "sc520_wdt"
#define PFX OUR_NAME ": "

/*
 * 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 int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 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
		printk(KERN_WARNING PFX
			"Heartbeat lost! Will not ping the watchdog\n");
}

/*
 *	Utility routines
 */

static void wdt_config(int writeval)
{
	__u16 dummy;
	unsigned long flags;

	/* buy some time (ping) */
	spin_lock_irqsave(&wdt_spinlock, flags);
	dummy = 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);

	printk(KERN_INFO PFX "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);

	printk(KERN_INFO PFX "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 {
		printk(KERN_CRIT PFX
			"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);
		printk(KERN_INFO PFX
		    "timeout value must be 1 <= timeout <= 3600, using %d\n",
							WATCHDOG_TIMEOUT);
	}

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

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

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

	printk(KERN_INFO PFX
	   "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");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
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 <[email protected]>
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 <[email protected]>
	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 <[email protected]>
	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 <[email protected]>
	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 <[email protected]>
	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
	55	#include <linux/module.h>
	56	#include <linux/moduleparam.h>
	57	#include <linux/types.h>
	58	#include <linux/timer.h>
	59	#include <linux/miscdevice.h>
	60	#include <linux/watchdog.h>
	61	#include <linux/fs.h>
	62	#include <linux/ioport.h>
	63	#include <linux/notifier.h>
	64	#include <linux/reboot.h>
	65	#include <linux/init.h>
4e57b681	66	#include <linux/jiffies.h>
ff948060 AC	67	#include <linux/io.h>
ff948060 AC	68	#include <linux/uaccess.h>
1da177e4	69
1da177e4 LT	70	#include <asm/system.h>
	71
	72	#define OUR_NAME "sc520_wdt"
	73	#define PFX OUR_NAME ": "
	74
	75	/*
	76	* The AMD Elan SC520 timeout value is 492us times a power of 2 (0-7)
	77	*
	78	* 0: 492us 2: 1.01s 4: 4.03s 6: 16.22s
	79	* 1: 503ms 3: 2.01s 5: 8.05s 7: 32.21s
	80	*
	81	* We will program the SC520 watchdog for a timeout of 2.01s.
	82	* If we reset the watchdog every ~250ms we should be safe.
	83	*/
	84
	85	#define WDT_INTERVAL (HZ/4+1)
	86
	87	/*
	88	* We must not require too good response from the userspace daemon.
	89	* Here we require the userspace daemon to send us a heartbeat
	90	* char to /dev/watchdog every 30 seconds.
	91	*/
	92
	93	#define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
ff948060 AC	94	/* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
ff948060 AC	95	static int timeout = WATCHDOG_TIMEOUT;
1da177e4	96	module_param(timeout, int, 0);
ff948060 AC	97	MODULE_PARM_DESC(timeout,
	98	"Watchdog timeout in seconds. (1 <= timeout <= 3600, default="
	99	__MODULE_STRING(WATCHDOG_TIMEOUT) ")");
1da177e4	100
4bfdf378	101	static int nowayout = WATCHDOG_NOWAYOUT;
1da177e4	102	module_param(nowayout, int, 0);
ff948060 AC	103	MODULE_PARM_DESC(nowayout,
	104	"Watchdog cannot be stopped once started (default="
	105	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
1da177e4 LT	106
	107	/*
	108	* AMD Elan SC520 - Watchdog Timer Registers
	109	*/
	110	#define MMCR_BASE 0xfffef000 /* The default base address */
	111	#define OFFS_WDTMRCTL 0xCB0 /* Watchdog Timer Control Register */
	112
	113	/* WDT Control Register bit definitions */
	114	#define WDT_EXP_SEL_01 0x0001 /* [01] Time-out = 496 us (with 33 Mhz clk). */
	115	#define WDT_EXP_SEL_02 0x0002 /* [02] Time-out = 508 ms (with 33 Mhz clk). */
	116	#define WDT_EXP_SEL_03 0x0004 /* [03] Time-out = 1.02 s (with 33 Mhz clk). */
	117	#define WDT_EXP_SEL_04 0x0008 /* [04] Time-out = 2.03 s (with 33 Mhz clk). */
	118	#define WDT_EXP_SEL_05 0x0010 /* [05] Time-out = 4.07 s (with 33 Mhz clk). */
	119	#define WDT_EXP_SEL_06 0x0020 /* [06] Time-out = 8.13 s (with 33 Mhz clk). */
	120	#define WDT_EXP_SEL_07 0x0040 /* [07] Time-out = 16.27s (with 33 Mhz clk). */
	121	#define WDT_EXP_SEL_08 0x0080 /* [08] Time-out = 32.54s (with 33 Mhz clk). */
	122	#define WDT_IRQ_FLG 0x1000 /* [12] Interrupt Request Flag */
	123	#define WDT_WRST_ENB 0x4000 /* [14] Watchdog Timer Reset Enable */
	124	#define WDT_ENB 0x8000 /* [15] Watchdog Timer Enable */
	125
	126	static __u16 __iomem *wdtmrctl;
	127
	128	static void wdt_timer_ping(unsigned long);
82eb7c50	129	static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
1da177e4 LT	130	static unsigned long next_heartbeat;
	131	static unsigned long wdt_is_open;
	132	static char wdt_expect_close;
c7dfd0cc	133	static DEFINE_SPINLOCK(wdt_spinlock);
1da177e4 LT	134
	135	/*
	136	* Whack the dog
	137	*/
	138
	139	static void wdt_timer_ping(unsigned long data)
	140	{
	141	/* If we got a heartbeat pulse within the WDT_US_INTERVAL
	142	* we agree to ping the WDT
	143	*/
ff948060	144	if (time_before(jiffies, next_heartbeat)) {
1da177e4 LT	145	/* Ping the WDT */
	146	spin_lock(&wdt_spinlock);
	147	writew(0xAAAA, wdtmrctl);
	148	writew(0x5555, wdtmrctl);
	149	spin_unlock(&wdt_spinlock);
	150
	151	/* Re-set the timer interval */
82eb7c50	152	mod_timer(&timer, jiffies + WDT_INTERVAL);
ff948060 AC	153	} else
	154	printk(KERN_WARNING PFX
	155	"Heartbeat lost! Will not ping the watchdog\n");
1da177e4 LT	156	}
	157
	158	/*
	159	* Utility routines
	160	*/
	161
	162	static void wdt_config(int writeval)
	163	{
	164	__u16 dummy;
	165	unsigned long flags;
	166
	167	/* buy some time (ping) */
	168	spin_lock_irqsave(&wdt_spinlock, flags);
ff948060	169	dummy = readw(wdtmrctl); /* ensure write synchronization */
1da177e4 LT	170	writew(0xAAAA, wdtmrctl);
	171	writew(0x5555, wdtmrctl);
	172	/* unlock WDT = make WDT configuration register writable one time */
	173	writew(0x3333, wdtmrctl);
	174	writew(0xCCCC, wdtmrctl);
	175	/* write WDT configuration register */
	176	writew(writeval, wdtmrctl);
	177	spin_unlock_irqrestore(&wdt_spinlock, flags);
	178	}
	179
	180	static int wdt_startup(void)
	181	{
	182	next_heartbeat = jiffies + (timeout * HZ);
	183
	184	/* Start the timer */
82eb7c50	185	mod_timer(&timer, jiffies + WDT_INTERVAL);
1da177e4 LT	186
	187	/* Start the watchdog */
	188	wdt_config(WDT_ENB \| WDT_WRST_ENB \| WDT_EXP_SEL_04);
	189
	190	printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
	191	return 0;
	192	}
	193
	194	static int wdt_turnoff(void)
	195	{
	196	/* Stop the timer */
	197	del_timer(&timer);
	198
	199	/* Stop the watchdog */
	200	wdt_config(0);
	201
	202	printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
	203	return 0;
	204	}
	205
	206	static int wdt_keepalive(void)
	207	{
	208	/* user land ping */
	209	next_heartbeat = jiffies + (timeout * HZ);
	210	return 0;
	211	}
	212
	213	static int wdt_set_heartbeat(int t)
	214	{
	215	if ((t < 1) \|\| (t > 3600)) /* arbitrary upper limit */
	216	return -EINVAL;
	217
	218	timeout = t;
	219	return 0;
	220	}
	221
	222	/*
	223	* /dev/watchdog handling
	224	*/
	225
ff948060 AC	226	static ssize_t fop_write(struct file file, const char __user buf,
ff948060 AC	227	size_t count, loff_t *ppos)
1da177e4 LT	228	{
1da177e4 LT	229	/* See if we got the magic character 'V' and reload the timer */
ff948060	230	if (count) {
1da177e4 LT	231	if (!nowayout) {
	232	size_t ofs;
	233
	234	/* note: just in case someone wrote the magic character
	235	* five months ago... */
	236	wdt_expect_close = 0;
	237
	238	/* now scan */
ff948060	239	for (ofs = 0; ofs != count; ofs++) {
1da177e4 LT	240	char c;
	241	if (get_user(c, buf + ofs))
	242	return -EFAULT;
ff948060	243	if (c == 'V')
1da177e4 LT	244	wdt_expect_close = 42;
	245	}
	246	}
	247
ff948060 AC	248	/* Well, anyhow someone wrote to us, we should
ff948060 AC	249	return that favour */
1da177e4 LT	250	wdt_keepalive();
	251	}
	252	return count;
	253	}
	254
ff948060	255	static int fop_open(struct inode inode, struct file file)
1da177e4	256	{
1da177e4	257	/* Just in case we're already talking to someone... */
ff948060	258	if (test_and_set_bit(0, &wdt_is_open))
1da177e4 LT	259	return -EBUSY;
	260	if (nowayout)
	261	__module_get(THIS_MODULE);
	262
	263	/* Good, fire up the show */
	264	wdt_startup();
6abe78bf	265	return nonseekable_open(inode, file);
1da177e4 LT	266	}
1da177e4 LT	267
ff948060	268	static int fop_close(struct inode inode, struct file file)
1da177e4	269	{
ff948060	270	if (wdt_expect_close == 42)
1da177e4	271	wdt_turnoff();
ff948060 AC	272	else {
	273	printk(KERN_CRIT PFX
	274	"Unexpected close, not stopping watchdog!\n");
1da177e4 LT	275	wdt_keepalive();
	276	}
	277	clear_bit(0, &wdt_is_open);
	278	wdt_expect_close = 0;
	279	return 0;
	280	}
	281
9b748ed0	282	static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1da177e4 LT	283	{
	284	void __user argp = (void __user )arg;
	285	int __user *p = argp;
ff948060 AC	286	static const struct watchdog_info ident = {
	287	.options = WDIOF_KEEPALIVEPING \| WDIOF_SETTIMEOUT
	288	\| WDIOF_MAGICCLOSE,
1da177e4 LT	289	.firmware_version = 1,
	290	.identity = "SC520",
	291	};
	292
5eb82498	293	switch (cmd) {
ff948060 AC	294	case WDIOC_GETSUPPORT:
	295	return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
	296	case WDIOC_GETSTATUS:
	297	case WDIOC_GETBOOTSTATUS:
	298	return put_user(0, p);
ff948060 AC	299	case WDIOC_SETOPTIONS:
	300	{
	301	int new_options, retval = -EINVAL;
1da177e4	302
ff948060 AC	303	if (get_user(new_options, p))
	304	return -EFAULT;
	305
	306	if (new_options & WDIOS_DISABLECARD) {
	307	wdt_turnoff();
	308	retval = 0;
	309	}
1da177e4	310
ff948060 AC	311	if (new_options & WDIOS_ENABLECARD) {
	312	wdt_startup();
	313	retval = 0;
1da177e4	314	}
1da177e4	315
ff948060 AC	316	return retval;
ff948060 AC	317	}
0c06090c WVS	318	case WDIOC_KEEPALIVE:
	319	wdt_keepalive();
	320	return 0;
ff948060 AC	321	case WDIOC_SETTIMEOUT:
	322	{
	323	int new_timeout;
1da177e4	324
ff948060 AC	325	if (get_user(new_timeout, p))
ff948060 AC	326	return -EFAULT;
1da177e4	327
ff948060 AC	328	if (wdt_set_heartbeat(new_timeout))
	329	return -EINVAL;
	330
	331	wdt_keepalive();
	332	/* Fall through */
	333	}
	334	case WDIOC_GETTIMEOUT:
	335	return put_user(timeout, p);
0c06090c WVS	336	default:
0c06090c WVS	337	return -ENOTTY;
1da177e4 LT	338	}
	339	}
	340
62322d25	341	static const struct file_operations wdt_fops = {
1da177e4 LT	342	.owner = THIS_MODULE,
	343	.llseek = no_llseek,
	344	.write = fop_write,
	345	.open = fop_open,
	346	.release = fop_close,
9b748ed0	347	.unlocked_ioctl = fop_ioctl,
1da177e4 LT	348	};
	349
	350	static struct miscdevice wdt_miscdev = {
	351	.minor = WATCHDOG_MINOR,
	352	.name = "watchdog",
	353	.fops = &wdt_fops,
	354	};
	355
	356	/*
	357	* Notifier for system down
	358	*/
	359
	360	static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
	361	void *unused)
	362	{
ff948060	363	if (code == SYS_DOWN \|\| code == SYS_HALT)
1da177e4 LT	364	wdt_turnoff();
	365	return NOTIFY_DONE;
	366	}
	367
	368	/*
	369	* The WDT needs to learn about soft shutdowns in order to
	370	* turn the timebomb registers off.
	371	*/
	372
	373	static struct notifier_block wdt_notifier = {
	374	.notifier_call = wdt_notify_sys,
	375	};
	376
	377	static void __exit sc520_wdt_unload(void)
	378	{
	379	if (!nowayout)
	380	wdt_turnoff();
	381
	382	/* Deregister */
	383	misc_deregister(&wdt_miscdev);
	384	unregister_reboot_notifier(&wdt_notifier);
	385	iounmap(wdtmrctl);
	386	}
	387
	388	static int __init sc520_wdt_init(void)
	389	{
	390	int rc = -EBUSY;
	391
ff948060 AC	392	/* Check that the timeout value is within it's range ;
ff948060 AC	393	if not reset to the default */
1da177e4 LT	394	if (wdt_set_heartbeat(timeout)) {
1da177e4 LT	395	wdt_set_heartbeat(WATCHDOG_TIMEOUT);
ff948060 AC	396	printk(KERN_INFO PFX
	397	"timeout value must be 1 <= timeout <= 3600, using %d\n",
	398	WATCHDOG_TIMEOUT);
1da177e4 LT	399	}
	400
	401	wdtmrctl = ioremap((unsigned long)(MMCR_BASE + OFFS_WDTMRCTL), 2);
	402	if (!wdtmrctl) {
	403	printk(KERN_ERR PFX "Unable to remap memory\n");
	404	rc = -ENOMEM;
	405	goto err_out_region2;
	406	}
	407
	408	rc = register_reboot_notifier(&wdt_notifier);
	409	if (rc) {
ff948060 AC	410	printk(KERN_ERR PFX
ff948060 AC	411	"cannot register reboot notifier (err=%d)\n", rc);
1da177e4 LT	412	goto err_out_ioremap;
	413	}
	414
	415	rc = misc_register(&wdt_miscdev);
	416	if (rc) {
ff948060 AC	417	printk(KERN_ERR PFX
	418	"cannot register miscdev on minor=%d (err=%d)\n",
	419	WATCHDOG_MINOR, rc);
1da177e4 LT	420	goto err_out_notifier;
	421	}
	422
ff948060 AC	423	printk(KERN_INFO PFX
	424	"WDT driver for SC520 initialised. timeout=%d sec (nowayout=%d)\n",
	425	timeout, nowayout);
1da177e4 LT	426
	427	return 0;
	428
	429	err_out_notifier:
	430	unregister_reboot_notifier(&wdt_notifier);
	431	err_out_ioremap:
	432	iounmap(wdtmrctl);
	433	err_out_region2:
	434	return rc;
	435	}
	436
	437	module_init(sc520_wdt_init);
	438	module_exit(sc520_wdt_unload);
	439
	440	MODULE_AUTHOR("Scott and Bill Jennings");
143a2e54 WVS	441	MODULE_DESCRIPTION(
143a2e54 WVS	442	"Driver for watchdog timer in AMD \"Elan\" SC520 uProcessor");
1da177e4 LT	443	MODULE_LICENSE("GPL");
1da177e4 LT	444	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);