drivers/watchdog/ar7_wdt.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * drivers/watchdog/ar7_wdt.c
  *
  * Copyright (C) 2007 Nicolas Thill <nico@openwrt.org>
  * Copyright (c) 2005 Enrik Berkhan <Enrik.Berkhan@akk.org>
  *
  * Some code taken from:
  * National Semiconductor SCx200 Watchdog support
  * Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
  *
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/errno.h>
 #include <linux/miscdevice.h>
 #include <linux/platform_device.h>
 #include <linux/watchdog.h>
 #include <linux/fs.h>
 #include <linux/ioport.h>
 #include <linux/io.h>
 #include <linux/uaccess.h>
 #include <linux/clk.h>

 #include <asm/addrspace.h>
 #include <asm/mach-ar7/ar7.h>

 #define LONGNAME "TI AR7 Watchdog Timer"

 MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
 MODULE_DESCRIPTION(LONGNAME);
 MODULE_LICENSE("GPL");

 static int margin = 60;
 module_param(margin, int, 0);
 MODULE_PARM_DESC(margin, "Watchdog margin in seconds");

 static bool nowayout = WATCHDOG_NOWAYOUT;
 module_param(nowayout, bool, 0);
 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");

 #define READ_REG(x) readl((void __iomem *)&(x))
 #define WRITE_REG(x, v) writel((v), (void __iomem *)&(x))

 struct ar7_wdt {
 	u32 kick_lock;
 	u32 kick;
 	u32 change_lock;
 	u32 change;
 	u32 disable_lock;
 	u32 disable;
 	u32 prescale_lock;
 	u32 prescale;
 };

 static unsigned long wdt_is_open;
 static unsigned expect_close;
 static DEFINE_SPINLOCK(wdt_lock);

 /* XXX currently fixed, allows max margin ~68.72 secs */
 #define prescale_value 0xffff

 /* Resource of the WDT registers */
 static struct resource *ar7_regs_wdt;
 /* Pointer to the remapped WDT IO space */
 static struct ar7_wdt *ar7_wdt;

 static struct clk *vbus_clk;

 static void ar7_wdt_kick(u32 value)
 {
 	WRITE_REG(ar7_wdt->kick_lock, 0x5555);
 	if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
 		WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
 		if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
 			WRITE_REG(ar7_wdt->kick, value);
 			return;
 		}
 	}
 	pr_err("failed to unlock WDT kick reg\n");
 }

 static void ar7_wdt_prescale(u32 value)
 {
 	WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
 	if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
 		WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
 		if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
 			WRITE_REG(ar7_wdt->prescale, value);
 			return;
 		}
 	}
 	pr_err("failed to unlock WDT prescale reg\n");
 }

 static void ar7_wdt_change(u32 value)
 {
 	WRITE_REG(ar7_wdt->change_lock, 0x6666);
 	if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
 		WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
 		if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
 			WRITE_REG(ar7_wdt->change, value);
 			return;
 		}
 	}
 	pr_err("failed to unlock WDT change reg\n");
 }

 static void ar7_wdt_disable(u32 value)
 {
 	WRITE_REG(ar7_wdt->disable_lock, 0x7777);
 	if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
 		WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
 		if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
 			WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
 			if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
 				WRITE_REG(ar7_wdt->disable, value);
 				return;
 			}
 		}
 	}
 	pr_err("failed to unlock WDT disable reg\n");
 }

 static void ar7_wdt_update_margin(int new_margin)
 {
 	u32 change;
 	u32 vbus_rate;

 	vbus_rate = clk_get_rate(vbus_clk);
 	change = new_margin * (vbus_rate / prescale_value);
 	if (change < 1)
 		change = 1;
 	if (change > 0xffff)
 		change = 0xffff;
 	ar7_wdt_change(change);
 	margin = change * prescale_value / vbus_rate;
 	pr_info("timer margin %d seconds (prescale %d, change %d, freq %d)\n",
 		margin, prescale_value, change, vbus_rate);
 }

 static void ar7_wdt_enable_wdt(void)
 {
 	pr_debug("enabling watchdog timer\n");
 	ar7_wdt_disable(1);
 	ar7_wdt_kick(1);
 }

 static void ar7_wdt_disable_wdt(void)
 {
 	pr_debug("disabling watchdog timer\n");
 	ar7_wdt_disable(0);
 }

 static int ar7_wdt_open(struct inode *inode, struct file *file)
 {
 	/* only allow one at a time */
 	if (test_and_set_bit(0, &wdt_is_open))
 		return -EBUSY;
 	ar7_wdt_enable_wdt();
 	expect_close = 0;

 	return stream_open(inode, file);
 }

 static int ar7_wdt_release(struct inode *inode, struct file *file)
 {
 	if (!expect_close)
 		pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
 	else if (!nowayout)
 		ar7_wdt_disable_wdt();
 	clear_bit(0, &wdt_is_open);
 	return 0;
 }

 static ssize_t ar7_wdt_write(struct file *file, const char *data,
 			     size_t len, loff_t *ppos)
 {
 	/* check for a magic close character */
 	if (len) {
 		size_t i;

 		spin_lock(&wdt_lock);
 		ar7_wdt_kick(1);
 		spin_unlock(&wdt_lock);

 		expect_close = 0;
 		for (i = 0; i < len; ++i) {
 			char c;
 			if (get_user(c, data + i))
 				return -EFAULT;
 			if (c == 'V')
 				expect_close = 1;
 		}

 	}
 	return len;
 }

 static long ar7_wdt_ioctl(struct file *file,
 					unsigned int cmd, unsigned long arg)
 {
 	static const struct watchdog_info ident = {
 		.identity = LONGNAME,
 		.firmware_version = 1,
 		.options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
 						WDIOF_MAGICCLOSE),
 	};
 	int new_margin;

 	switch (cmd) {
 	case WDIOC_GETSUPPORT:
 		if (copy_to_user((struct watchdog_info *)arg, &ident,
 				sizeof(ident)))
 			return -EFAULT;
 		return 0;
 	case WDIOC_GETSTATUS:
 	case WDIOC_GETBOOTSTATUS:
 		if (put_user(0, (int *)arg))
 			return -EFAULT;
 		return 0;
 	case WDIOC_KEEPALIVE:
 		ar7_wdt_kick(1);
 		return 0;
 	case WDIOC_SETTIMEOUT:
 		if (get_user(new_margin, (int *)arg))
 			return -EFAULT;
 		if (new_margin < 1)
 			return -EINVAL;

 		spin_lock(&wdt_lock);
 		ar7_wdt_update_margin(new_margin);
 		ar7_wdt_kick(1);
 		spin_unlock(&wdt_lock);
 		/* Fall through */

 	case WDIOC_GETTIMEOUT:
 		if (put_user(margin, (int *)arg))
 			return -EFAULT;
 		return 0;
 	default:
 		return -ENOTTY;
 	}
 }

 static const struct file_operations ar7_wdt_fops = {
 	.owner		= THIS_MODULE,
 	.write		= ar7_wdt_write,
 	.unlocked_ioctl	= ar7_wdt_ioctl,
 	.open		= ar7_wdt_open,
 	.release	= ar7_wdt_release,
 	.llseek		= no_llseek,
 };

 static struct miscdevice ar7_wdt_miscdev = {
 	.minor		= WATCHDOG_MINOR,
 	.name		= "watchdog",
 	.fops		= &ar7_wdt_fops,
 };

 static int ar7_wdt_probe(struct platform_device *pdev)
 {
 	int rc;

 	ar7_regs_wdt =
 		platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs");
 	ar7_wdt = devm_ioremap_resource(&pdev->dev, ar7_regs_wdt);
 	if (IS_ERR(ar7_wdt))
 		return PTR_ERR(ar7_wdt);

 	vbus_clk = clk_get(NULL, "vbus");
 	if (IS_ERR(vbus_clk)) {
 		pr_err("could not get vbus clock\n");
 		return PTR_ERR(vbus_clk);
 	}

 	ar7_wdt_disable_wdt();
 	ar7_wdt_prescale(prescale_value);
 	ar7_wdt_update_margin(margin);

 	rc = misc_register(&ar7_wdt_miscdev);
 	if (rc) {
 		pr_err("unable to register misc device\n");
 		goto out;
 	}
 	return 0;

 out:
 	clk_put(vbus_clk);
 	vbus_clk = NULL;
 	return rc;
 }

 static int ar7_wdt_remove(struct platform_device *pdev)
 {
 	misc_deregister(&ar7_wdt_miscdev);
 	clk_put(vbus_clk);
 	vbus_clk = NULL;
 	return 0;
 }

 static void ar7_wdt_shutdown(struct platform_device *pdev)
 {
 	if (!nowayout)
 		ar7_wdt_disable_wdt();
 }

 static struct platform_driver ar7_wdt_driver = {
 	.probe = ar7_wdt_probe,
 	.remove = ar7_wdt_remove,
 	.shutdown = ar7_wdt_shutdown,
 	.driver = {
 		.name = "ar7_wdt",
 	},
 };

 module_platform_driver(ar7_wdt_driver);
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* drivers/watchdog/ar7_wdt.c
	*
	* Copyright (C) 2007 Nicolas Thill <nico@openwrt.org>
	* Copyright (c) 2005 Enrik Berkhan <Enrik.Berkhan@akk.org>
	*
	* Some code taken from:
	* National Semiconductor SCx200 Watchdog support
	* Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
	*
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/module.h>
	#include <linux/moduleparam.h>
	#include <linux/errno.h>
	#include <linux/miscdevice.h>
	#include <linux/platform_device.h>
	#include <linux/watchdog.h>
	#include <linux/fs.h>
	#include <linux/ioport.h>
	#include <linux/io.h>
	#include <linux/uaccess.h>
	#include <linux/clk.h>

	#include <asm/addrspace.h>
	#include <asm/mach-ar7/ar7.h>

	#define LONGNAME "TI AR7 Watchdog Timer"

	MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
	MODULE_DESCRIPTION(LONGNAME);
	MODULE_LICENSE("GPL");

	static int margin = 60;
	module_param(margin, int, 0);
	MODULE_PARM_DESC(margin, "Watchdog margin in seconds");

	static bool nowayout = WATCHDOG_NOWAYOUT;
	module_param(nowayout, bool, 0);
	MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");

	#define READ_REG(x) readl((void __iomem *)&(x))
	#define WRITE_REG(x, v) writel((v), (void __iomem *)&(x))

	struct ar7_wdt {
	u32 kick_lock;
	u32 kick;
	u32 change_lock;
	u32 change;
	u32 disable_lock;
	u32 disable;
	u32 prescale_lock;
	u32 prescale;
	};

	static unsigned long wdt_is_open;
	static unsigned expect_close;
	static DEFINE_SPINLOCK(wdt_lock);

	/* XXX currently fixed, allows max margin ~68.72 secs */
	#define prescale_value 0xffff

	/* Resource of the WDT registers */
	static struct resource *ar7_regs_wdt;
	/* Pointer to the remapped WDT IO space */
	static struct ar7_wdt *ar7_wdt;

	static struct clk *vbus_clk;

	static void ar7_wdt_kick(u32 value)
	{
	WRITE_REG(ar7_wdt->kick_lock, 0x5555);
	if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
	WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
	if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
	WRITE_REG(ar7_wdt->kick, value);
	return;
	}
	}
	pr_err("failed to unlock WDT kick reg\n");
	}

	static void ar7_wdt_prescale(u32 value)
	{
	WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
	if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
	WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
	if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
	WRITE_REG(ar7_wdt->prescale, value);
	return;
	}
	}
	pr_err("failed to unlock WDT prescale reg\n");
	}

	static void ar7_wdt_change(u32 value)
	{
	WRITE_REG(ar7_wdt->change_lock, 0x6666);
	if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
	WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
	if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
	WRITE_REG(ar7_wdt->change, value);
	return;
	}
	}
	pr_err("failed to unlock WDT change reg\n");
	}

	static void ar7_wdt_disable(u32 value)
	{
	WRITE_REG(ar7_wdt->disable_lock, 0x7777);
	if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
	WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
	if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
	WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
	if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
	WRITE_REG(ar7_wdt->disable, value);
	return;
	}
	}
	}
	pr_err("failed to unlock WDT disable reg\n");
	}

	static void ar7_wdt_update_margin(int new_margin)
	{
	u32 change;
	u32 vbus_rate;

	vbus_rate = clk_get_rate(vbus_clk);
	change = new_margin * (vbus_rate / prescale_value);
	if (change < 1)
	change = 1;
	if (change > 0xffff)
	change = 0xffff;
	ar7_wdt_change(change);
	margin = change * prescale_value / vbus_rate;
	pr_info("timer margin %d seconds (prescale %d, change %d, freq %d)\n",
	margin, prescale_value, change, vbus_rate);
	}

	static void ar7_wdt_enable_wdt(void)
	{
	pr_debug("enabling watchdog timer\n");
	ar7_wdt_disable(1);
	ar7_wdt_kick(1);
	}

	static void ar7_wdt_disable_wdt(void)
	{
	pr_debug("disabling watchdog timer\n");
	ar7_wdt_disable(0);
	}

	static int ar7_wdt_open(struct inode inode, struct file file)
	{
	/* only allow one at a time */
	if (test_and_set_bit(0, &wdt_is_open))
	return -EBUSY;
	ar7_wdt_enable_wdt();
	expect_close = 0;

	return stream_open(inode, file);
	}

	static int ar7_wdt_release(struct inode inode, struct file file)
	{
	if (!expect_close)
	pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
	else if (!nowayout)
	ar7_wdt_disable_wdt();
	clear_bit(0, &wdt_is_open);
	return 0;
	}

	static ssize_t ar7_wdt_write(struct file file, const char data,
	size_t len, loff_t *ppos)
	{
	/* check for a magic close character */
	if (len) {
	size_t i;

	spin_lock(&wdt_lock);
	ar7_wdt_kick(1);
	spin_unlock(&wdt_lock);

	expect_close = 0;
	for (i = 0; i < len; ++i) {
	char c;
	if (get_user(c, data + i))
	return -EFAULT;
	if (c == 'V')
	expect_close = 1;
	}

	}
	return len;
	}

	static long ar7_wdt_ioctl(struct file *file,
	unsigned int cmd, unsigned long arg)
	{
	static const struct watchdog_info ident = {
	.identity = LONGNAME,
	.firmware_version = 1,
	.options = (WDIOF_SETTIMEOUT \| WDIOF_KEEPALIVEPING \|
	WDIOF_MAGICCLOSE),
	};
	int new_margin;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
	if (copy_to_user((struct watchdog_info *)arg, &ident,
	sizeof(ident)))
	return -EFAULT;
	return 0;
	case WDIOC_GETSTATUS:
	case WDIOC_GETBOOTSTATUS:
	if (put_user(0, (int *)arg))
	return -EFAULT;
	return 0;
	case WDIOC_KEEPALIVE:
	ar7_wdt_kick(1);
	return 0;
	case WDIOC_SETTIMEOUT:
	if (get_user(new_margin, (int *)arg))
	return -EFAULT;
	if (new_margin < 1)
	return -EINVAL;

	spin_lock(&wdt_lock);
	ar7_wdt_update_margin(new_margin);
	ar7_wdt_kick(1);
	spin_unlock(&wdt_lock);
	/* Fall through */

	case WDIOC_GETTIMEOUT:
	if (put_user(margin, (int *)arg))
	return -EFAULT;
	return 0;
	default:
	return -ENOTTY;
	}
	}

	static const struct file_operations ar7_wdt_fops = {
	.owner = THIS_MODULE,
	.write = ar7_wdt_write,
	.unlocked_ioctl = ar7_wdt_ioctl,
	.open = ar7_wdt_open,
	.release = ar7_wdt_release,
	.llseek = no_llseek,
	};

	static struct miscdevice ar7_wdt_miscdev = {
	.minor = WATCHDOG_MINOR,
	.name = "watchdog",
	.fops = &ar7_wdt_fops,
	};

	static int ar7_wdt_probe(struct platform_device *pdev)
	{
	int rc;

	ar7_regs_wdt =
	platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs");
	ar7_wdt = devm_ioremap_resource(&pdev->dev, ar7_regs_wdt);
	if (IS_ERR(ar7_wdt))
	return PTR_ERR(ar7_wdt);

	vbus_clk = clk_get(NULL, "vbus");
	if (IS_ERR(vbus_clk)) {
	pr_err("could not get vbus clock\n");
	return PTR_ERR(vbus_clk);
	}

	ar7_wdt_disable_wdt();
	ar7_wdt_prescale(prescale_value);
	ar7_wdt_update_margin(margin);

	rc = misc_register(&ar7_wdt_miscdev);
	if (rc) {
	pr_err("unable to register misc device\n");
	goto out;
	}
	return 0;

	out:
	clk_put(vbus_clk);
	vbus_clk = NULL;
	return rc;
	}

	static int ar7_wdt_remove(struct platform_device *pdev)
	{
	misc_deregister(&ar7_wdt_miscdev);
	clk_put(vbus_clk);
	vbus_clk = NULL;
	return 0;
	}

	static void ar7_wdt_shutdown(struct platform_device *pdev)
	{
	if (!nowayout)
	ar7_wdt_disable_wdt();
	}

	static struct platform_driver ar7_wdt_driver = {
	.probe = ar7_wdt_probe,
	.remove = ar7_wdt_remove,
	.shutdown = ar7_wdt_shutdown,
	.driver = {
	.name = "ar7_wdt",
	},
	};

	module_platform_driver(ar7_wdt_driver);