/*
   *  Broadcom BCM63xx SoC watchdog driver
   *
   *  Copyright (C) 2007, Miguel Gaio <miguel.gaio@efixo.com>
   *  Copyright (C) 2008, Florian Fainelli <florian@openwrt.org>
   *
   *  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.
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/bitops.h>
  #include <linux/errno.h>
  #include <linux/fs.h>

  #include <linux/io.h>

  #include <linux/kernel.h>
  #include <linux/miscdevice.h>
  #include <linux/module.h>
  #include <linux/moduleparam.h>

  #include <linux/types.h>
  #include <linux/uaccess.h>
  #include <linux/watchdog.h>
  #include <linux/timer.h>
  #include <linux/jiffies.h>
  #include <linux/interrupt.h>
  #include <linux/ptrace.h>
  #include <linux/resource.h>
  #include <linux/platform_device.h>
  
  #include <bcm63xx_cpu.h>
  #include <bcm63xx_io.h>
  #include <bcm63xx_regs.h>
  #include <bcm63xx_timer.h>
  
  #define PFX KBUILD_MODNAME
  
  #define WDT_HZ		50000000 /* Fclk */
  #define WDT_DEFAULT_TIME	30      /* seconds */
  #define WDT_MAX_TIME		256     /* seconds */
  
  static struct {
  	void __iomem *regs;
  	struct timer_list timer;

  	unsigned long inuse;
  	atomic_t ticks;
  } bcm63xx_wdt_device;
  
  static int expect_close;
  
  static int wdt_time = WDT_DEFAULT_TIME;

  static bool nowayout = WATCHDOG_NOWAYOUT;
  module_param(nowayout, bool, 0);

  MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  
  /* HW functions */
  static void bcm63xx_wdt_hw_start(void)
  {
  	bcm_writel(0xfffffffe, bcm63xx_wdt_device.regs + WDT_DEFVAL_REG);
  	bcm_writel(WDT_START_1, bcm63xx_wdt_device.regs + WDT_CTL_REG);
  	bcm_writel(WDT_START_2, bcm63xx_wdt_device.regs + WDT_CTL_REG);
  }
  
  static void bcm63xx_wdt_hw_stop(void)
  {
  	bcm_writel(WDT_STOP_1, bcm63xx_wdt_device.regs + WDT_CTL_REG);
  	bcm_writel(WDT_STOP_2, bcm63xx_wdt_device.regs + WDT_CTL_REG);
  }
  
  static void bcm63xx_wdt_isr(void *data)
  {
  	struct pt_regs *regs = get_irq_regs();
  
  	die(PFX " fire", regs);
  }
  
  static void bcm63xx_timer_tick(unsigned long unused)
  {
  	if (!atomic_dec_and_test(&bcm63xx_wdt_device.ticks)) {
  		bcm63xx_wdt_hw_start();
  		mod_timer(&bcm63xx_wdt_device.timer, jiffies + HZ);
  	} else

  		pr_crit("watchdog will restart system
  ");

  }
  
  static void bcm63xx_wdt_pet(void)
  {
  	atomic_set(&bcm63xx_wdt_device.ticks, wdt_time);
  }
  
  static void bcm63xx_wdt_start(void)
  {
  	bcm63xx_wdt_pet();
  	bcm63xx_timer_tick(0);
  }
  
  static void bcm63xx_wdt_pause(void)
  {
  	del_timer_sync(&bcm63xx_wdt_device.timer);
  	bcm63xx_wdt_hw_stop();
  }
  
  static int bcm63xx_wdt_settimeout(int new_time)
  {
  	if ((new_time <= 0) || (new_time > WDT_MAX_TIME))
  		return -EINVAL;
  
  	wdt_time = new_time;
  
  	return 0;
  }
  
  static int bcm63xx_wdt_open(struct inode *inode, struct file *file)
  {
  	if (test_and_set_bit(0, &bcm63xx_wdt_device.inuse))
  		return -EBUSY;
  
  	bcm63xx_wdt_start();
  	return nonseekable_open(inode, file);
  }
  
  static int bcm63xx_wdt_release(struct inode *inode, struct file *file)
  {
  	if (expect_close == 42)
  		bcm63xx_wdt_pause();
  	else {

  		pr_crit("Unexpected close, not stopping watchdog!
  ");

  		bcm63xx_wdt_start();
  	}
  	clear_bit(0, &bcm63xx_wdt_device.inuse);
  	expect_close = 0;
  	return 0;
  }
  
  static ssize_t bcm63xx_wdt_write(struct file *file, const char *data,
  				size_t len, loff_t *ppos)
  {
  	if (len) {
  		if (!nowayout) {
  			size_t i;
  
  			/* In case it was set long ago */
  			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;
  			}
  		}
  		bcm63xx_wdt_pet();
  	}
  	return len;
  }
  
  static struct watchdog_info bcm63xx_wdt_info = {
  	.identity       = PFX,
  	.options        = WDIOF_SETTIMEOUT |
  				WDIOF_KEEPALIVEPING |
  				WDIOF_MAGICCLOSE,
  };
  
  
  static long bcm63xx_wdt_ioctl(struct file *file, unsigned int cmd,
  				unsigned long arg)
  {
  	void __user *argp = (void __user *)arg;
  	int __user *p = argp;
  	int new_value, retval = -EINVAL;
  
  	switch (cmd) {
  	case WDIOC_GETSUPPORT:
  		return copy_to_user(argp, &bcm63xx_wdt_info,
  			sizeof(bcm63xx_wdt_info)) ? -EFAULT : 0;
  
  	case WDIOC_GETSTATUS:
  	case WDIOC_GETBOOTSTATUS:
  		return put_user(0, p);
  
  	case WDIOC_SETOPTIONS:
  		if (get_user(new_value, p))
  			return -EFAULT;
  
  		if (new_value & WDIOS_DISABLECARD) {
  			bcm63xx_wdt_pause();
  			retval = 0;
  		}
  		if (new_value & WDIOS_ENABLECARD) {
  			bcm63xx_wdt_start();
  			retval = 0;
  		}
  
  		return retval;
  
  	case WDIOC_KEEPALIVE:
  		bcm63xx_wdt_pet();
  		return 0;
  
  	case WDIOC_SETTIMEOUT:
  		if (get_user(new_value, p))
  			return -EFAULT;
  
  		if (bcm63xx_wdt_settimeout(new_value))
  			return -EINVAL;
  
  		bcm63xx_wdt_pet();
  
  	case WDIOC_GETTIMEOUT:
  		return put_user(wdt_time, p);
  
  	default:
  		return -ENOTTY;
  
  	}
  }

  static const struct file_operations bcm63xx_wdt_fops = {
  	.owner		= THIS_MODULE,
  	.llseek		= no_llseek,
  	.write		= bcm63xx_wdt_write,
  	.unlocked_ioctl	= bcm63xx_wdt_ioctl,
  	.open		= bcm63xx_wdt_open,
  	.release	= bcm63xx_wdt_release,
  };
  
  static struct miscdevice bcm63xx_wdt_miscdev = {
  	.minor	= WATCHDOG_MINOR,
  	.name	= "watchdog",
  	.fops	= &bcm63xx_wdt_fops,
  };

  static int bcm63xx_wdt_probe(struct platform_device *pdev)

  {
  	int ret;
  	struct resource *r;
  
  	setup_timer(&bcm63xx_wdt_device.timer, bcm63xx_timer_tick, 0L);
  
  	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!r) {
  		dev_err(&pdev->dev, "failed to get resources
  ");
  		return -ENODEV;
  	}

  	bcm63xx_wdt_device.regs = devm_ioremap_nocache(&pdev->dev, r->start,
  							resource_size(r));

  	if (!bcm63xx_wdt_device.regs) {
  		dev_err(&pdev->dev, "failed to remap I/O resources
  ");
  		return -ENXIO;
  	}
  
  	ret = bcm63xx_timer_register(TIMER_WDT_ID, bcm63xx_wdt_isr, NULL);
  	if (ret < 0) {
  		dev_err(&pdev->dev, "failed to register wdt timer isr
  ");

  		return ret;

  	}
  
  	if (bcm63xx_wdt_settimeout(wdt_time)) {
  		bcm63xx_wdt_settimeout(WDT_DEFAULT_TIME);
  		dev_info(&pdev->dev,
  			": wdt_time value must be 1 <= wdt_time <= 256, using %d
  ",
  			wdt_time);
  	}

  	ret = misc_register(&bcm63xx_wdt_miscdev);
  	if (ret < 0) {
  		dev_err(&pdev->dev, "failed to register watchdog device
  ");

  		goto unregister_timer;

  	}
  
  	dev_info(&pdev->dev, " started, timer margin: %d sec
  ",
  						WDT_DEFAULT_TIME);
  
  	return 0;

  unregister_timer:
  	bcm63xx_timer_unregister(TIMER_WDT_ID);

  	return ret;
  }

  static int bcm63xx_wdt_remove(struct platform_device *pdev)

  {
  	if (!nowayout)
  		bcm63xx_wdt_pause();
  
  	misc_deregister(&bcm63xx_wdt_miscdev);

  	bcm63xx_timer_unregister(TIMER_WDT_ID);

  	return 0;
  }

  static void bcm63xx_wdt_shutdown(struct platform_device *pdev)
  {
  	bcm63xx_wdt_pause();
  }

  static struct platform_driver bcm63xx_wdt_driver = {

  	.probe	= bcm63xx_wdt_probe,

  	.remove = bcm63xx_wdt_remove,

  	.shutdown = bcm63xx_wdt_shutdown,

  	.driver = {
  		.name = "bcm63xx-wdt",
  	}
  };

  module_platform_driver(bcm63xx_wdt_driver);

  
  MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>");
  MODULE_AUTHOR("Florian Fainelli <florian@openwrt.org>");
  MODULE_DESCRIPTION("Driver for the Broadcom BCM63xx SoC watchdog");
  MODULE_LICENSE("GPL");

  MODULE_ALIAS("platform:bcm63xx-wdt");