drivers/watchdog/sp805_wdt.c - kernel/common - Git at Google

 /*
  * drivers/char/watchdog/sp805-wdt.c
  *
  * Watchdog driver for ARM SP805 watchdog module
  *
  * Copyright (C) 2010 ST Microelectronics
  * Viresh Kumar<[email protected]>
  *
  * This file is licensed under the terms of the GNU General Public
  * License version 2 or later. This program is licensed "as is" without any
  * warranty of any kind, whether express or implied.
  */

 #include <linux/device.h>
 #include <linux/resource.h>
 #include <linux/amba/bus.h>
 #include <linux/bitops.h>
 #include <linux/clk.h>
 #include <linux/fs.h>
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/ioport.h>
 #include <linux/kernel.h>
 #include <linux/math64.h>
 #include <linux/miscdevice.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/types.h>
 #include <linux/uaccess.h>
 #include <linux/watchdog.h>

 /* default timeout in seconds */
 #define DEFAULT_TIMEOUT		60

 #define MODULE_NAME		"sp805-wdt"

 /* watchdog register offsets and masks */
 #define WDTLOAD			0x000
 	#define LOAD_MIN	0x00000001
 	#define LOAD_MAX	0xFFFFFFFF
 #define WDTVALUE		0x004
 #define WDTCONTROL		0x008
 	/* control register masks */
 	#define	INT_ENABLE	(1 << 0)
 	#define	RESET_ENABLE	(1 << 1)
 #define WDTINTCLR		0x00C
 #define WDTRIS			0x010
 #define WDTMIS			0x014
 	#define INT_MASK	(1 << 0)
 #define WDTLOCK			0xC00
 	#define	UNLOCK		0x1ACCE551
 	#define	LOCK		0x00000001

 /**
  * struct sp805_wdt: sp805 wdt device structure
  *
  * lock: spin lock protecting dev structure and io access
  * base: base address of wdt
  * clk: clock structure of wdt
  * dev: amba device structure of wdt
  * status: current status of wdt
  * load_val: load value to be set for current timeout
  * timeout: current programmed timeout
  */
 struct sp805_wdt {
 	spinlock_t			lock;
 	void __iomem			*base;
 	struct clk			*clk;
 	struct amba_device		*adev;
 	unsigned long			status;
 	#define WDT_BUSY		0
 	#define WDT_CAN_BE_CLOSED	1
 	unsigned int			load_val;
 	unsigned int			timeout;
 };

 /* local variables */
 static struct sp805_wdt *wdt;
 static int nowayout = WATCHDOG_NOWAYOUT;

 /* This routine finds load value that will reset system in required timout */
 static void wdt_setload(unsigned int timeout)
 {
 	u64 load, rate;

 	rate = clk_get_rate(wdt->clk);

 	/*
 	 * sp805 runs counter with given value twice, after the end of first
 	 * counter it gives an interrupt and then starts counter again. If
 	 * interrupt already occured then it resets the system. This is why
 	 * load is half of what should be required.
 	 */
 	load = div_u64(rate, 2) * timeout - 1;

 	load = (load > LOAD_MAX) ? LOAD_MAX : load;
 	load = (load < LOAD_MIN) ? LOAD_MIN : load;

 	spin_lock(&wdt->lock);
 	wdt->load_val = load;
 	/* roundup timeout to closest positive integer value */
 	wdt->timeout = div_u64((load + 1) * 2 + (rate / 2), rate);
 	spin_unlock(&wdt->lock);
 }

 /* returns number of seconds left for reset to occur */
 static u32 wdt_timeleft(void)
 {
 	u64 load, rate;

 	rate = clk_get_rate(wdt->clk);

 	spin_lock(&wdt->lock);
 	load = readl(wdt->base + WDTVALUE);

 	/*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
 	if (!(readl(wdt->base + WDTRIS) & INT_MASK))
 		load += wdt->load_val + 1;
 	spin_unlock(&wdt->lock);

 	return div_u64(load, rate);
 }

 /* enables watchdog timers reset */
 static void wdt_enable(void)
 {
 	spin_lock(&wdt->lock);

 	writel(UNLOCK, wdt->base + WDTLOCK);
 	writel(wdt->load_val, wdt->base + WDTLOAD);
 	writel(INT_MASK, wdt->base + WDTINTCLR);
 	writel(INT_ENABLE | RESET_ENABLE, wdt->base + WDTCONTROL);
 	writel(LOCK, wdt->base + WDTLOCK);

 	spin_unlock(&wdt->lock);
 }

 /* disables watchdog timers reset */
 static void wdt_disable(void)
 {
 	spin_lock(&wdt->lock);

 	writel(UNLOCK, wdt->base + WDTLOCK);
 	writel(0, wdt->base + WDTCONTROL);
 	writel(0, wdt->base + WDTLOAD);
 	writel(LOCK, wdt->base + WDTLOCK);

 	spin_unlock(&wdt->lock);
 }

 static ssize_t sp805_wdt_write(struct file *file, const char *data,
 		size_t len, loff_t *ppos)
 {
 	if (len) {
 		if (!nowayout) {
 			size_t i;

 			clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);

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

 				if (get_user(c, data + i))
 					return -EFAULT;
 				/* Check for Magic Close character */
 				if (c == 'V') {
 					set_bit(WDT_CAN_BE_CLOSED,
 							&wdt->status);
 					break;
 				}
 			}
 		}
 		wdt_enable();
 	}
 	return len;
 }

 static const struct watchdog_info ident = {
 	.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
 	.identity = MODULE_NAME,
 };

 static long sp805_wdt_ioctl(struct file *file, unsigned int cmd,
 		unsigned long arg)
 {
 	int ret = -ENOTTY;
 	unsigned int timeout;

 	switch (cmd) {
 	case WDIOC_GETSUPPORT:
 		ret = copy_to_user((struct watchdog_info *)arg, &ident,
 				sizeof(ident)) ? -EFAULT : 0;
 		break;

 	case WDIOC_GETSTATUS:
 		ret = put_user(0, (int *)arg);
 		break;

 	case WDIOC_KEEPALIVE:
 		wdt_enable();
 		ret = 0;
 		break;

 	case WDIOC_SETTIMEOUT:
 		ret = get_user(timeout, (unsigned int *)arg);
 		if (ret)
 			break;

 		wdt_setload(timeout);

 		wdt_enable();
 		/* Fall through */

 	case WDIOC_GETTIMEOUT:
 		ret = put_user(wdt->timeout, (unsigned int *)arg);
 		break;
 	case WDIOC_GETTIMELEFT:
 		ret = put_user(wdt_timeleft(), (unsigned int *)arg);
 		break;
 	}
 	return ret;
 }

 static int sp805_wdt_open(struct inode *inode, struct file *file)
 {
 	int ret = 0;

 	if (test_and_set_bit(WDT_BUSY, &wdt->status))
 		return -EBUSY;

 	ret = clk_enable(wdt->clk);
 	if (ret) {
 		dev_err(&wdt->adev->dev, "clock enable fail");
 		goto err;
 	}

 	wdt_enable();

 	/* can not be closed, once enabled */
 	clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);
 	return nonseekable_open(inode, file);

 err:
 	clear_bit(WDT_BUSY, &wdt->status);
 	return ret;
 }

 static int sp805_wdt_release(struct inode *inode, struct file *file)
 {
 	if (!test_bit(WDT_CAN_BE_CLOSED, &wdt->status)) {
 		clear_bit(WDT_BUSY, &wdt->status);
 		dev_warn(&wdt->adev->dev, "Device closed unexpectedly\n");
 		return 0;
 	}

 	wdt_disable();
 	clk_disable(wdt->clk);
 	clear_bit(WDT_BUSY, &wdt->status);

 	return 0;
 }

 static const struct file_operations sp805_wdt_fops = {
 	.owner = THIS_MODULE,
 	.llseek = no_llseek,
 	.write = sp805_wdt_write,
 	.unlocked_ioctl = sp805_wdt_ioctl,
 	.open = sp805_wdt_open,
 	.release = sp805_wdt_release,
 };

 static struct miscdevice sp805_wdt_miscdev = {
 	.minor = WATCHDOG_MINOR,
 	.name = "watchdog",
 	.fops = &sp805_wdt_fops,
 };

 static int __devinit
 sp805_wdt_probe(struct amba_device *adev, struct amba_id *id)
 {
 	int ret = 0;

 	if (!request_mem_region(adev->res.start, resource_size(&adev->res),
 				"sp805_wdt")) {
 		dev_warn(&adev->dev, "Failed to get memory region resource\n");
 		ret = -ENOENT;
 		goto err;
 	}

 	wdt = kzalloc(sizeof(*wdt), GFP_KERNEL);
 	if (!wdt) {
 		dev_warn(&adev->dev, "Kzalloc failed\n");
 		ret = -ENOMEM;
 		goto err_kzalloc;
 	}

 	wdt->clk = clk_get(&adev->dev, NULL);
 	if (IS_ERR(wdt->clk)) {
 		dev_warn(&adev->dev, "Clock not found\n");
 		ret = PTR_ERR(wdt->clk);
 		goto err_clk_get;
 	}

 	wdt->base = ioremap(adev->res.start, resource_size(&adev->res));
 	if (!wdt->base) {
 		ret = -ENOMEM;
 		dev_warn(&adev->dev, "ioremap fail\n");
 		goto err_ioremap;
 	}

 	wdt->adev = adev;
 	spin_lock_init(&wdt->lock);
 	wdt_setload(DEFAULT_TIMEOUT);

 	ret = misc_register(&sp805_wdt_miscdev);
 	if (ret < 0) {
 		dev_warn(&adev->dev, "cannot register misc device\n");
 		goto err_misc_register;
 	}

 	dev_info(&adev->dev, "registration successful\n");
 	return 0;

 err_misc_register:
 	iounmap(wdt->base);
 err_ioremap:
 	clk_put(wdt->clk);
 err_clk_get:
 	kfree(wdt);
 	wdt = NULL;
 err_kzalloc:
 	release_mem_region(adev->res.start, resource_size(&adev->res));
 err:
 	dev_err(&adev->dev, "Probe Failed!!!\n");
 	return ret;
 }

 static int __devexit sp805_wdt_remove(struct amba_device *adev)
 {
 	misc_deregister(&sp805_wdt_miscdev);
 	iounmap(wdt->base);
 	clk_put(wdt->clk);
 	kfree(wdt);
 	release_mem_region(adev->res.start, resource_size(&adev->res));

 	return 0;
 }

 static struct amba_id sp805_wdt_ids[] __initdata = {
 	{
 		.id	= 0x00141805,
 		.mask	= 0x00ffffff,
 	},
 	{ 0, 0 },
 };

 static struct amba_driver sp805_wdt_driver = {
 	.drv = {
 		.name	= MODULE_NAME,
 	},
 	.id_table	= sp805_wdt_ids,
 	.probe		= sp805_wdt_probe,
 	.remove = __devexit_p(sp805_wdt_remove),
 };

 static int __init sp805_wdt_init(void)
 {
 	return amba_driver_register(&sp805_wdt_driver);
 }
 module_init(sp805_wdt_init);

 static void __exit sp805_wdt_exit(void)
 {
 	amba_driver_unregister(&sp805_wdt_driver);
 }
 module_exit(sp805_wdt_exit);

 module_param(nowayout, int, 0);
 MODULE_PARM_DESC(nowayout,
 		"Set to 1 to keep watchdog running after device release");

 MODULE_AUTHOR("Viresh Kumar <[email protected]>");
 MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
	/*
	* drivers/char/watchdog/sp805-wdt.c
	*
	* Watchdog driver for ARM SP805 watchdog module
	*
	* Copyright (C) 2010 ST Microelectronics
	* Viresh Kumar<[email protected]>
	*
	* This file is licensed under the terms of the GNU General Public
	* License version 2 or later. This program is licensed "as is" without any
	* warranty of any kind, whether express or implied.
	*/

	#include <linux/device.h>
	#include <linux/resource.h>
	#include <linux/amba/bus.h>
	#include <linux/bitops.h>
	#include <linux/clk.h>
	#include <linux/fs.h>
	#include <linux/init.h>
	#include <linux/io.h>
	#include <linux/ioport.h>
	#include <linux/kernel.h>
	#include <linux/math64.h>
	#include <linux/miscdevice.h>
	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/slab.h>
	#include <linux/spinlock.h>
	#include <linux/types.h>
	#include <linux/uaccess.h>
	#include <linux/watchdog.h>

	/* default timeout in seconds */
	#define DEFAULT_TIMEOUT 60

	#define MODULE_NAME "sp805-wdt"

	/* watchdog register offsets and masks */
	#define WDTLOAD 0x000
	#define LOAD_MIN 0x00000001
	#define LOAD_MAX 0xFFFFFFFF
	#define WDTVALUE 0x004
	#define WDTCONTROL 0x008
	/* control register masks */
	#define INT_ENABLE (1 << 0)
	#define RESET_ENABLE (1 << 1)
	#define WDTINTCLR 0x00C
	#define WDTRIS 0x010
	#define WDTMIS 0x014
	#define INT_MASK (1 << 0)
	#define WDTLOCK 0xC00
	#define UNLOCK 0x1ACCE551
	#define LOCK 0x00000001

	/**
	* struct sp805_wdt: sp805 wdt device structure
	*
	* lock: spin lock protecting dev structure and io access
	* base: base address of wdt
	* clk: clock structure of wdt
	* dev: amba device structure of wdt
	* status: current status of wdt
	* load_val: load value to be set for current timeout
	* timeout: current programmed timeout
	*/
	struct sp805_wdt {
	spinlock_t lock;
	void __iomem *base;
	struct clk *clk;
	struct amba_device *adev;
	unsigned long status;
	#define WDT_BUSY 0
	#define WDT_CAN_BE_CLOSED 1
	unsigned int load_val;
	unsigned int timeout;
	};

	/* local variables */
	static struct sp805_wdt *wdt;
	static int nowayout = WATCHDOG_NOWAYOUT;

	/* This routine finds load value that will reset system in required timout */
	static void wdt_setload(unsigned int timeout)
	{
	u64 load, rate;

	rate = clk_get_rate(wdt->clk);

	/*
	* sp805 runs counter with given value twice, after the end of first
	* counter it gives an interrupt and then starts counter again. If
	* interrupt already occured then it resets the system. This is why
	* load is half of what should be required.
	*/
	load = div_u64(rate, 2) * timeout - 1;

	load = (load > LOAD_MAX) ? LOAD_MAX : load;
	load = (load < LOAD_MIN) ? LOAD_MIN : load;

	spin_lock(&wdt->lock);
	wdt->load_val = load;
	/* roundup timeout to closest positive integer value */
	wdt->timeout = div_u64((load + 1) * 2 + (rate / 2), rate);
	spin_unlock(&wdt->lock);
	}

	/* returns number of seconds left for reset to occur */
	static u32 wdt_timeleft(void)
	{
	u64 load, rate;

	rate = clk_get_rate(wdt->clk);

	spin_lock(&wdt->lock);
	load = readl(wdt->base + WDTVALUE);

	/If the interrupt is inactive then time left is WDTValue + WDTLoad. /
	if (!(readl(wdt->base + WDTRIS) & INT_MASK))
	load += wdt->load_val + 1;
	spin_unlock(&wdt->lock);

	return div_u64(load, rate);
	}

	/* enables watchdog timers reset */
	static void wdt_enable(void)
	{
	spin_lock(&wdt->lock);

	writel(UNLOCK, wdt->base + WDTLOCK);
	writel(wdt->load_val, wdt->base + WDTLOAD);
	writel(INT_MASK, wdt->base + WDTINTCLR);
	writel(INT_ENABLE \| RESET_ENABLE, wdt->base + WDTCONTROL);
	writel(LOCK, wdt->base + WDTLOCK);

	spin_unlock(&wdt->lock);
	}

	/* disables watchdog timers reset */
	static void wdt_disable(void)
	{
	spin_lock(&wdt->lock);

	writel(UNLOCK, wdt->base + WDTLOCK);
	writel(0, wdt->base + WDTCONTROL);
	writel(0, wdt->base + WDTLOAD);
	writel(LOCK, wdt->base + WDTLOCK);

	spin_unlock(&wdt->lock);
	}

	static ssize_t sp805_wdt_write(struct file file, const char data,
	size_t len, loff_t *ppos)
	{
	if (len) {
	if (!nowayout) {
	size_t i;

	clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);

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

	if (get_user(c, data + i))
	return -EFAULT;
	/* Check for Magic Close character */
	if (c == 'V') {
	set_bit(WDT_CAN_BE_CLOSED,
	&wdt->status);
	break;
	}
	}
	}
	wdt_enable();
	}
	return len;
	}

	static const struct watchdog_info ident = {
	.options = WDIOF_MAGICCLOSE \| WDIOF_SETTIMEOUT \| WDIOF_KEEPALIVEPING,
	.identity = MODULE_NAME,
	};

	static long sp805_wdt_ioctl(struct file *file, unsigned int cmd,
	unsigned long arg)
	{
	int ret = -ENOTTY;
	unsigned int timeout;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
	ret = copy_to_user((struct watchdog_info *)arg, &ident,
	sizeof(ident)) ? -EFAULT : 0;
	break;

	case WDIOC_GETSTATUS:
	ret = put_user(0, (int *)arg);
	break;

	case WDIOC_KEEPALIVE:
	wdt_enable();
	ret = 0;
	break;

	case WDIOC_SETTIMEOUT:
	ret = get_user(timeout, (unsigned int *)arg);
	if (ret)
	break;

	wdt_setload(timeout);

	wdt_enable();
	/* Fall through */

	case WDIOC_GETTIMEOUT:
	ret = put_user(wdt->timeout, (unsigned int *)arg);
	break;
	case WDIOC_GETTIMELEFT:
	ret = put_user(wdt_timeleft(), (unsigned int *)arg);
	break;
	}
	return ret;
	}

	static int sp805_wdt_open(struct inode inode, struct file file)
	{
	int ret = 0;

	if (test_and_set_bit(WDT_BUSY, &wdt->status))
	return -EBUSY;

	ret = clk_enable(wdt->clk);
	if (ret) {
	dev_err(&wdt->adev->dev, "clock enable fail");
	goto err;
	}

	wdt_enable();

	/* can not be closed, once enabled */
	clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);
	return nonseekable_open(inode, file);

	err:
	clear_bit(WDT_BUSY, &wdt->status);
	return ret;
	}

	static int sp805_wdt_release(struct inode inode, struct file file)
	{
	if (!test_bit(WDT_CAN_BE_CLOSED, &wdt->status)) {
	clear_bit(WDT_BUSY, &wdt->status);
	dev_warn(&wdt->adev->dev, "Device closed unexpectedly\n");
	return 0;
	}

	wdt_disable();
	clk_disable(wdt->clk);
	clear_bit(WDT_BUSY, &wdt->status);

	return 0;
	}

	static const struct file_operations sp805_wdt_fops = {
	.owner = THIS_MODULE,
	.llseek = no_llseek,
	.write = sp805_wdt_write,
	.unlocked_ioctl = sp805_wdt_ioctl,
	.open = sp805_wdt_open,
	.release = sp805_wdt_release,
	};

	static struct miscdevice sp805_wdt_miscdev = {
	.minor = WATCHDOG_MINOR,
	.name = "watchdog",
	.fops = &sp805_wdt_fops,
	};

	static int __devinit
	sp805_wdt_probe(struct amba_device adev, struct amba_id id)
	{
	int ret = 0;

	if (!request_mem_region(adev->res.start, resource_size(&adev->res),
	"sp805_wdt")) {
	dev_warn(&adev->dev, "Failed to get memory region resource\n");
	ret = -ENOENT;
	goto err;
	}

	wdt = kzalloc(sizeof(*wdt), GFP_KERNEL);
	if (!wdt) {
	dev_warn(&adev->dev, "Kzalloc failed\n");
	ret = -ENOMEM;
	goto err_kzalloc;
	}

	wdt->clk = clk_get(&adev->dev, NULL);
	if (IS_ERR(wdt->clk)) {
	dev_warn(&adev->dev, "Clock not found\n");
	ret = PTR_ERR(wdt->clk);
	goto err_clk_get;
	}

	wdt->base = ioremap(adev->res.start, resource_size(&adev->res));
	if (!wdt->base) {
	ret = -ENOMEM;
	dev_warn(&adev->dev, "ioremap fail\n");
	goto err_ioremap;
	}

	wdt->adev = adev;
	spin_lock_init(&wdt->lock);
	wdt_setload(DEFAULT_TIMEOUT);

	ret = misc_register(&sp805_wdt_miscdev);
	if (ret < 0) {
	dev_warn(&adev->dev, "cannot register misc device\n");
	goto err_misc_register;
	}

	dev_info(&adev->dev, "registration successful\n");
	return 0;

	err_misc_register:
	iounmap(wdt->base);
	err_ioremap:
	clk_put(wdt->clk);
	err_clk_get:
	kfree(wdt);
	wdt = NULL;
	err_kzalloc:
	release_mem_region(adev->res.start, resource_size(&adev->res));
	err:
	dev_err(&adev->dev, "Probe Failed!!!\n");
	return ret;
	}

	static int __devexit sp805_wdt_remove(struct amba_device *adev)
	{
	misc_deregister(&sp805_wdt_miscdev);
	iounmap(wdt->base);
	clk_put(wdt->clk);
	kfree(wdt);
	release_mem_region(adev->res.start, resource_size(&adev->res));

	return 0;
	}

	static struct amba_id sp805_wdt_ids[] __initdata = {
	{
	.id = 0x00141805,
	.mask = 0x00ffffff,
	},
	{ 0, 0 },
	};

	static struct amba_driver sp805_wdt_driver = {
	.drv = {
	.name = MODULE_NAME,
	},
	.id_table = sp805_wdt_ids,
	.probe = sp805_wdt_probe,
	.remove = __devexit_p(sp805_wdt_remove),
	};

	static int __init sp805_wdt_init(void)
	{
	return amba_driver_register(&sp805_wdt_driver);
	}
	module_init(sp805_wdt_init);

	static void __exit sp805_wdt_exit(void)
	{
	amba_driver_unregister(&sp805_wdt_driver);
	}
	module_exit(sp805_wdt_exit);

	module_param(nowayout, int, 0);
	MODULE_PARM_DESC(nowayout,
	"Set to 1 to keep watchdog running after device release");

	MODULE_AUTHOR("Viresh Kumar <[email protected]>");
	MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);