/*

   * omap_wdt.c

   *

   * Watchdog driver for the TI OMAP 16xx & 24xx/34xx 32KHz (non-secure) watchdog

   *
   * Author: MontaVista Software, Inc.
   *	 <gdavis@mvista.com> or <source@mvista.com>
   *
   * 2003 (c) MontaVista Software, Inc. This file is licensed under the
   * terms of the GNU General Public License version 2. This program is
   * licensed "as is" without any warranty of any kind, whether express
   * or implied.
   *
   * History:
   *
   * 20030527: George G. Davis <gdavis@mvista.com>
   *	Initially based on linux-2.4.19-rmk7-pxa1/drivers/char/sa1100_wdt.c
   *	(c) Copyright 2000 Oleg Drokin <green@crimea.edu>

   *	Based on SoftDog driver by Alan Cox <alan@lxorguk.ukuu.org.uk>

   *
   * Copyright (c) 2004 Texas Instruments.
   *	1. Modified to support OMAP1610 32-KHz watchdog timer
   *	2. Ported to 2.6 kernel
   *
   * Copyright (c) 2005 David Brownell
   *	Use the driver model and standard identifiers; handle bigger timeouts.
   */
  
  #include <linux/module.h>

  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/fs.h>
  #include <linux/mm.h>
  #include <linux/miscdevice.h>
  #include <linux/watchdog.h>
  #include <linux/reboot.h>

  #include <linux/init.h>
  #include <linux/err.h>
  #include <linux/platform_device.h>
  #include <linux/moduleparam.h>

  #include <linux/bitops.h>

  #include <linux/io.h>

  #include <linux/uaccess.h>

  #include <linux/slab.h>

  #include <linux/pm_runtime.h>

  #include <mach/hardware.h>

  #include <plat/prcm.h>

  
  #include "omap_wdt.h"

  static struct platform_device *omap_wdt_dev;

  static unsigned timer_margin;
  module_param(timer_margin, uint, 0);
  MODULE_PARM_DESC(timer_margin, "initial watchdog timeout (in seconds)");

  static unsigned int wdt_trgr_pattern = 0x1234;

  static DEFINE_SPINLOCK(wdt_lock);

  struct omap_wdt_dev {
  	void __iomem    *base;          /* physical */
  	struct device   *dev;
  	int             omap_wdt_users;

  	struct resource *mem;
  	struct miscdevice omap_wdt_miscdev;
  };
  
  static void omap_wdt_ping(struct omap_wdt_dev *wdev)

  {

  	void __iomem    *base = wdev->base;

  	/* wait for posted write to complete */

  	while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x08)

  		cpu_relax();

  	wdt_trgr_pattern = ~wdt_trgr_pattern;

  	__raw_writel(wdt_trgr_pattern, (base + OMAP_WATCHDOG_TGR));

  	/* wait for posted write to complete */

  	while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x08)

  		cpu_relax();
  	/* reloaded WCRR from WLDR */
  }

  static void omap_wdt_enable(struct omap_wdt_dev *wdev)

  {

  	void __iomem *base = wdev->base;

  	/* Sequence to enable the watchdog */

  	__raw_writel(0xBBBB, base + OMAP_WATCHDOG_SPR);
  	while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x10)

  		cpu_relax();

  	__raw_writel(0x4444, base + OMAP_WATCHDOG_SPR);
  	while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x10)

  		cpu_relax();
  }

  static void omap_wdt_disable(struct omap_wdt_dev *wdev)

  {

  	void __iomem *base = wdev->base;

  	/* sequence required to disable watchdog */

  	__raw_writel(0xAAAA, base + OMAP_WATCHDOG_SPR);	/* TIMER_MODE */
  	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x10)

  		cpu_relax();

  	__raw_writel(0x5555, base + OMAP_WATCHDOG_SPR);	/* TIMER_MODE */
  	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x10)

  		cpu_relax();
  }
  
  static void omap_wdt_adjust_timeout(unsigned new_timeout)
  {
  	if (new_timeout < TIMER_MARGIN_MIN)
  		new_timeout = TIMER_MARGIN_DEFAULT;
  	if (new_timeout > TIMER_MARGIN_MAX)
  		new_timeout = TIMER_MARGIN_MAX;
  	timer_margin = new_timeout;
  }

  static void omap_wdt_set_timeout(struct omap_wdt_dev *wdev)

  {
  	u32 pre_margin = GET_WLDR_VAL(timer_margin);

  	void __iomem *base = wdev->base;

  	pm_runtime_get_sync(wdev->dev);

  	/* just count up at 32 KHz */

  	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x04)

  		cpu_relax();

  	__raw_writel(pre_margin, base + OMAP_WATCHDOG_LDR);
  	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x04)

  		cpu_relax();

  
  	pm_runtime_put_sync(wdev->dev);

  }
  
  /*
   *	Allow only one task to hold it open
   */

  static int omap_wdt_open(struct inode *inode, struct file *file)
  {

  	struct omap_wdt_dev *wdev = platform_get_drvdata(omap_wdt_dev);
  	void __iomem *base = wdev->base;

  	if (test_and_set_bit(1, (unsigned long *)&(wdev->omap_wdt_users)))

  		return -EBUSY;

  	pm_runtime_get_sync(wdev->dev);

  
  	/* initialize prescaler */

  	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x01)

  		cpu_relax();

  	__raw_writel((1 << 5) | (PTV << 2), base + OMAP_WATCHDOG_CNTRL);
  	while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x01)

  		cpu_relax();

  	file->private_data = (void *) wdev;
  
  	omap_wdt_set_timeout(wdev);

  	omap_wdt_ping(wdev); /* trigger loading of new timeout value */

  	omap_wdt_enable(wdev);

  	pm_runtime_put_sync(wdev->dev);

  	return nonseekable_open(inode, file);

  }
  
  static int omap_wdt_release(struct inode *inode, struct file *file)
  {

  	struct omap_wdt_dev *wdev = file->private_data;

  	/*
  	 *      Shut off the timer unless NOWAYOUT is defined.
  	 */
  #ifndef CONFIG_WATCHDOG_NOWAYOUT

  	pm_runtime_get_sync(wdev->dev);

  	omap_wdt_disable(wdev);

  	pm_runtime_put_sync(wdev->dev);

  #else
  	printk(KERN_CRIT "omap_wdt: Unexpected close, not stopping!
  ");
  #endif

  	wdev->omap_wdt_users = 0;

  	return 0;
  }

  static ssize_t omap_wdt_write(struct file *file, const char __user *data,

  		size_t len, loff_t *ppos)
  {

  	struct omap_wdt_dev *wdev = file->private_data;

  	/* Refresh LOAD_TIME. */

  	if (len) {

  		pm_runtime_get_sync(wdev->dev);

  		spin_lock(&wdt_lock);

  		omap_wdt_ping(wdev);

  		spin_unlock(&wdt_lock);

  		pm_runtime_put_sync(wdev->dev);

  	}

  	return len;
  }

  static long omap_wdt_ioctl(struct file *file, unsigned int cmd,
  						unsigned long arg)

  {

  	struct omap_wdt_dev *wdev;

  	int new_margin;

  	static const struct watchdog_info ident = {

  		.identity = "OMAP Watchdog",
  		.options = WDIOF_SETTIMEOUT,
  		.firmware_version = 0,
  	};

  	wdev = file->private_data;

  
  	switch (cmd) {

  	case WDIOC_GETSUPPORT:
  		return copy_to_user((struct watchdog_info __user *)arg, &ident,
  				sizeof(ident));
  	case WDIOC_GETSTATUS:
  		return put_user(0, (int __user *)arg);
  	case WDIOC_GETBOOTSTATUS:
  		if (cpu_is_omap16xx())

  			return put_user(__raw_readw(ARM_SYSST),

  					(int __user *)arg);
  		if (cpu_is_omap24xx())
  			return put_user(omap_prcm_get_reset_sources(),
  					(int __user *)arg);

  		return put_user(0, (int __user *)arg);

  	case WDIOC_KEEPALIVE:

  		pm_runtime_get_sync(wdev->dev);

  		spin_lock(&wdt_lock);

  		omap_wdt_ping(wdev);

  		spin_unlock(&wdt_lock);

  		pm_runtime_put_sync(wdev->dev);

  		return 0;
  	case WDIOC_SETTIMEOUT:
  		if (get_user(new_margin, (int __user *)arg))
  			return -EFAULT;
  		omap_wdt_adjust_timeout(new_margin);

  		pm_runtime_get_sync(wdev->dev);

  		spin_lock(&wdt_lock);

  		omap_wdt_disable(wdev);
  		omap_wdt_set_timeout(wdev);
  		omap_wdt_enable(wdev);

  		omap_wdt_ping(wdev);

  		spin_unlock(&wdt_lock);

  		pm_runtime_put_sync(wdev->dev);

  		/* Fall */
  	case WDIOC_GETTIMEOUT:
  		return put_user(timer_margin, (int __user *)arg);

  	default:
  		return -ENOTTY;

  	}
  }

  static const struct file_operations omap_wdt_fops = {

  	.owner = THIS_MODULE,
  	.write = omap_wdt_write,

  	.unlocked_ioctl = omap_wdt_ioctl,

  	.open = omap_wdt_open,
  	.release = omap_wdt_release,

  	.llseek = no_llseek,

  };

  static int __devinit omap_wdt_probe(struct platform_device *pdev)

  {
  	struct resource *res, *mem;

  	struct omap_wdt_dev *wdev;

  	int ret;

  
  	/* reserve static register mappings */
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

  	if (!res) {
  		ret = -ENOENT;
  		goto err_get_resource;
  	}

  	if (omap_wdt_dev) {
  		ret = -EBUSY;
  		goto err_busy;
  	}

  	mem = request_mem_region(res->start, resource_size(res), pdev->name);

  	if (!mem) {
  		ret = -EBUSY;
  		goto err_busy;
  	}

  	wdev = kzalloc(sizeof(struct omap_wdt_dev), GFP_KERNEL);
  	if (!wdev) {
  		ret = -ENOMEM;

  		goto err_kzalloc;

  	}

  	wdev->omap_wdt_users = 0;
  	wdev->mem = mem;

  	wdev->dev = &pdev->dev;

  	wdev->base = ioremap(res->start, resource_size(res));

  	if (!wdev->base) {
  		ret = -ENOMEM;

  		goto err_ioremap;

  	}

  	platform_set_drvdata(pdev, wdev);

  	pm_runtime_enable(wdev->dev);
  	pm_runtime_get_sync(wdev->dev);

  	omap_wdt_disable(wdev);

  	omap_wdt_adjust_timeout(timer_margin);

  	wdev->omap_wdt_miscdev.parent = &pdev->dev;
  	wdev->omap_wdt_miscdev.minor = WATCHDOG_MINOR;
  	wdev->omap_wdt_miscdev.name = "watchdog";
  	wdev->omap_wdt_miscdev.fops = &omap_wdt_fops;
  
  	ret = misc_register(&(wdev->omap_wdt_miscdev));

  	if (ret)

  		goto err_misc;

  	pr_info("OMAP Watchdog Timer Rev 0x%02x: initial timeout %d sec
  ",

  		__raw_readl(wdev->base + OMAP_WATCHDOG_REV) & 0xFF,

  		timer_margin);

  	pm_runtime_put_sync(wdev->dev);

  	omap_wdt_dev = pdev;

  	return 0;

  err_misc:
  	platform_set_drvdata(pdev, NULL);
  	iounmap(wdev->base);
  
  err_ioremap:
  	wdev->base = NULL;

  	kfree(wdev);
  
  err_kzalloc:

  	release_mem_region(res->start, resource_size(res));

  
  err_busy:
  err_get_resource:

  	return ret;
  }
  
  static void omap_wdt_shutdown(struct platform_device *pdev)
  {

  	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

  	if (wdev->omap_wdt_users) {
  		pm_runtime_get_sync(wdev->dev);

  		omap_wdt_disable(wdev);

  		pm_runtime_put_sync(wdev->dev);
  	}

  }

  static int __devexit omap_wdt_remove(struct platform_device *pdev)

  {

  	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

  	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  
  	if (!res)
  		return -ENOENT;
  
  	misc_deregister(&(wdev->omap_wdt_miscdev));

  	release_mem_region(res->start, resource_size(res));

  	platform_set_drvdata(pdev, NULL);

  	iounmap(wdev->base);

  	kfree(wdev);
  	omap_wdt_dev = NULL;

  	return 0;
  }
  
  #ifdef	CONFIG_PM
  
  /* REVISIT ... not clear this is the best way to handle system suspend; and
   * it's very inappropriate for selective device suspend (e.g. suspending this
   * through sysfs rather than by stopping the watchdog daemon).  Also, this
   * may not play well enough with NOWAYOUT...
   */
  
  static int omap_wdt_suspend(struct platform_device *pdev, pm_message_t state)
  {

  	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

  	if (wdev->omap_wdt_users) {
  		pm_runtime_get_sync(wdev->dev);

  		omap_wdt_disable(wdev);

  		pm_runtime_put_sync(wdev->dev);
  	}

  	return 0;
  }
  
  static int omap_wdt_resume(struct platform_device *pdev)
  {

  	struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);

  	if (wdev->omap_wdt_users) {

  		pm_runtime_get_sync(wdev->dev);

  		omap_wdt_enable(wdev);
  		omap_wdt_ping(wdev);

  		pm_runtime_put_sync(wdev->dev);

  	}

  	return 0;
  }
  
  #else
  #define	omap_wdt_suspend	NULL
  #define	omap_wdt_resume		NULL
  #endif
  
  static struct platform_driver omap_wdt_driver = {
  	.probe		= omap_wdt_probe,

  	.remove		= __devexit_p(omap_wdt_remove),

  	.shutdown	= omap_wdt_shutdown,
  	.suspend	= omap_wdt_suspend,
  	.resume		= omap_wdt_resume,
  	.driver		= {
  		.owner	= THIS_MODULE,
  		.name	= "omap_wdt",
  	},
  };

  module_platform_driver(omap_wdt_driver);

  
  MODULE_AUTHOR("George G. Davis");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

  MODULE_ALIAS("platform:omap_wdt");