drivers/watchdog/sb_wdog.c - kernel/prism - Git at Google

 /*
  * Watchdog driver for SiByte SB1 SoCs
  *
  * Copyright (C) 2007 OnStor, Inc. * Andrew Sharp <andy.sharp@onstor.com>
  *
  * This driver is intended to make the second of two hardware watchdogs
  * on the Sibyte 12XX and 11XX SoCs available to the user.  There are two
  * such devices available on the SoC, but it seems that there isn't an
  * enumeration class for watchdogs in Linux like there is for RTCs.
  * The second is used rather than the first because it uses IRQ 1,
  * thereby avoiding all that IRQ 0 problematic nonsense.
  *
  * I have not tried this driver on a 1480 processor; it might work
  * just well enough to really screw things up.
  *
  * It is a simple timer, and there is an interrupt that is raised the
  * first time the timer expires.  The second time it expires, the chip
  * is reset and there is no way to redirect that NMI.  Which could
  * be problematic in some cases where this chip is sitting on the HT
  * bus and has just taken responsibility for providing a cache block.
  * Since the reset can't be redirected to the external reset pin, it is
  * possible that other HT connected processors might hang and not reset.
  * For Linux, a soft reset would probably be even worse than a hard reset.
  * There you have it.
  *
  * The timer takes 23 bits of a 64 bit register (?) as a count value,
  * and decrements the count every microsecond, for a max value of
  * 0x7fffff usec or about 8.3ish seconds.
  *
  * This watchdog borrows some user semantics from the softdog driver,
  * in that if you close the fd, it leaves the watchdog running, unless
  * you previously wrote a 'V' to the fd, in which case it disables
  * the watchdog when you close the fd like some other drivers.
  *
  * Based on various other watchdog drivers, which are probably all
  * loosely based on something Alan Cox wrote years ago.
  *
  *	(c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
  *						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.
  *
  */
 #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 - 0x10);
 	__raw_writeq(t & 0x7fffffUL, wdog);
 	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 {
 		printk(KERN_CRIT
 			"%s: Unexpected close, not stopping watchdog!\n",
 						ident.identity);
 		sbwdog_pet(user_dog);
 	}
 	clear_bit(0, &sbwdog_gate);
 	expect_close = 0;

 	return 0;
 }

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

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

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

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

 	return len;
 }

 static 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(__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)
 		printk(KERN_CRIT "%s in danger of initiating system reset "
 			"in %ld.%01ld seconds\n",
 			ident.identity,
 			wd_init / 1000000, (wd_init / 100000) % 10);
 	else
 		cfg |= 1;

 	__raw_writeb(cfg, wd_cfg_reg);

 	return IRQ_HANDLED;
 }

 static int __init sbwdog_init(void)
 {
 	int ret;

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

 	/*
 	 * get the resources
 	 */

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

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

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

 module_init(sbwdog_init);
 module_exit(sbwdog_exit);

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

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

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

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

 void platform_wd_setup(void)
 {
 	int ret;

 	ret = request_irq(1, sbwdog_interrupt, IRQF_DISABLED | IRQF_SHARED,
 		"Kernel Watchdog", IOADDR(A_SCD_WDOG_CFG_0));
 	if (ret) {
 		printk(KERN_CRIT
 		  "Watchdog IRQ zero(0) failed to be requested - %d\n", ret);
 	}
 }


  */
	/*
	* Watchdog driver for SiByte SB1 SoCs
	*
	* Copyright (C) 2007 OnStor, Inc. * Andrew Sharp <andy.sharp@onstor.com>
	*
	* This driver is intended to make the second of two hardware watchdogs
	* on the Sibyte 12XX and 11XX SoCs available to the user. There are two
	* such devices available on the SoC, but it seems that there isn't an
	* enumeration class for watchdogs in Linux like there is for RTCs.
	* The second is used rather than the first because it uses IRQ 1,
	* thereby avoiding all that IRQ 0 problematic nonsense.
	*
	* I have not tried this driver on a 1480 processor; it might work
	* just well enough to really screw things up.
	*
	* It is a simple timer, and there is an interrupt that is raised the
	* first time the timer expires. The second time it expires, the chip
	* is reset and there is no way to redirect that NMI. Which could
	* be problematic in some cases where this chip is sitting on the HT
	* bus and has just taken responsibility for providing a cache block.
	* Since the reset can't be redirected to the external reset pin, it is
	* possible that other HT connected processors might hang and not reset.
	* For Linux, a soft reset would probably be even worse than a hard reset.
	* There you have it.
	*
	* The timer takes 23 bits of a 64 bit register (?) as a count value,
	* and decrements the count every microsecond, for a max value of
	* 0x7fffff usec or about 8.3ish seconds.
	*
	* This watchdog borrows some user semantics from the softdog driver,
	* in that if you close the fd, it leaves the watchdog running, unless
	* you previously wrote a 'V' to the fd, in which case it disables
	* the watchdog when you close the fd like some other drivers.
	*
	* Based on various other watchdog drivers, which are probably all
	* loosely based on something Alan Cox wrote years ago.
	*
	* (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
	* 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.
	*
	*/
	#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 - 0x10);
	__raw_writeq(t & 0x7fffffUL, wdog);
	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 {
	printk(KERN_CRIT
	"%s: Unexpected close, not stopping watchdog!\n",
	ident.identity);
	sbwdog_pet(user_dog);
	}
	clear_bit(0, &sbwdog_gate);
	expect_close = 0;

	return 0;
	}

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

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

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

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

	return len;
	}

	static 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(__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)
	printk(KERN_CRIT "%s in danger of initiating system reset "
	"in %ld.%01ld seconds\n",
	ident.identity,
	wd_init / 1000000, (wd_init / 100000) % 10);
	else
	cfg \|= 1;

	__raw_writeb(cfg, wd_cfg_reg);

	return IRQ_HANDLED;
	}

	static int __init sbwdog_init(void)
	{
	int ret;

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

	/*
	* get the resources
	*/

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

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

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

	module_init(sbwdog_init);
	module_exit(sbwdog_exit);

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

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

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

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

	void platform_wd_setup(void)
	{
	int ret;

	ret = request_irq(1, sbwdog_interrupt, IRQF_DISABLED \| IRQF_SHARED,
	"Kernel Watchdog", IOADDR(A_SCD_WDOG_CFG_0));
	if (ret) {
	printk(KERN_CRIT
	"Watchdog IRQ zero(0) failed to be requested - %d\n", ret);
	}
	}


	*/