/*
   * txx9wdt: A Hardware Watchdog Driver for TXx9 SoCs
   *
   * Copyright (C) 2007 Atsushi Nemoto <anemo@mba.ocn.ne.jp>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/types.h>
  #include <linux/miscdevice.h>
  #include <linux/watchdog.h>
  #include <linux/fs.h>

  #include <linux/init.h>
  #include <linux/uaccess.h>
  #include <linux/platform_device.h>
  #include <linux/clk.h>
  #include <linux/err.h>
  #include <linux/io.h>
  #include <asm/txx9tmr.h>
  
  #define TIMER_MARGIN	60		/* Default is 60 seconds */
  
  static int timeout = TIMER_MARGIN;	/* in seconds */
  module_param(timeout, int, 0);
  MODULE_PARM_DESC(timeout,
  	"Watchdog timeout in seconds. "
  	"(0<timeout<((2^" __MODULE_STRING(TXX9_TIMER_BITS) ")/(IMCLK/256)), "
  	"default=" __MODULE_STRING(TIMER_MARGIN) ")");
  
  static int nowayout = WATCHDOG_NOWAYOUT;
  module_param(nowayout, int, 0);
  MODULE_PARM_DESC(nowayout,
  	"Watchdog cannot be stopped once started "
  	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  
  #define WD_TIMER_CCD	7	/* 1/256 */
  #define WD_TIMER_CLK	(clk_get_rate(txx9_imclk) / (2 << WD_TIMER_CCD))
  #define WD_MAX_TIMEOUT	((0xffffffff >> (32 - TXX9_TIMER_BITS)) / WD_TIMER_CLK)
  
  static unsigned long txx9wdt_alive;
  static int expect_close;
  static struct txx9_tmr_reg __iomem *txx9wdt_reg;
  static struct clk *txx9_imclk;

  static DEFINE_SPINLOCK(txx9_lock);

  
  static void txx9wdt_ping(void)
  {

  	spin_lock(&txx9_lock);

  	__raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);

  	spin_unlock(&txx9_lock);

  }
  
  static void txx9wdt_start(void)
  {

  	spin_lock(&txx9_lock);

  	__raw_writel(WD_TIMER_CLK * timeout, &txx9wdt_reg->cpra);
  	__raw_writel(WD_TIMER_CCD, &txx9wdt_reg->ccdr);
  	__raw_writel(0, &txx9wdt_reg->tisr);	/* clear pending interrupt */
  	__raw_writel(TXx9_TMTCR_TCE | TXx9_TMTCR_CCDE | TXx9_TMTCR_TMODE_WDOG,
  		     &txx9wdt_reg->tcr);
  	__raw_writel(TXx9_TMWTMR_TWIE | TXx9_TMWTMR_TWC, &txx9wdt_reg->wtmr);

  	spin_unlock(&txx9_lock);

  }
  
  static void txx9wdt_stop(void)
  {

  	spin_lock(&txx9_lock);

  	__raw_writel(TXx9_TMWTMR_WDIS, &txx9wdt_reg->wtmr);
  	__raw_writel(__raw_readl(&txx9wdt_reg->tcr) & ~TXx9_TMTCR_TCE,
  		     &txx9wdt_reg->tcr);

  	spin_unlock(&txx9_lock);

  }
  
  static int txx9wdt_open(struct inode *inode, struct file *file)
  {
  	if (test_and_set_bit(0, &txx9wdt_alive))
  		return -EBUSY;
  
  	if (__raw_readl(&txx9wdt_reg->tcr) & TXx9_TMTCR_TCE) {
  		clear_bit(0, &txx9wdt_alive);
  		return -EBUSY;
  	}
  
  	if (nowayout)
  		__module_get(THIS_MODULE);
  
  	txx9wdt_start();
  	return nonseekable_open(inode, file);
  }
  
  static int txx9wdt_release(struct inode *inode, struct file *file)
  {
  	if (expect_close)
  		txx9wdt_stop();
  	else {
  		printk(KERN_CRIT "txx9wdt: "
  		       "Unexpected close, not stopping watchdog!
  ");
  		txx9wdt_ping();
  	}
  	clear_bit(0, &txx9wdt_alive);
  	expect_close = 0;
  	return 0;
  }
  
  static ssize_t txx9wdt_write(struct file *file, const char __user *data,
  			     size_t len, loff_t *ppos)
  {
  	if (len) {
  		if (!nowayout) {
  			size_t i;
  
  			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;
  			}
  		}
  		txx9wdt_ping();
  	}
  	return len;
  }

  static long txx9wdt_ioctl(struct file *file, unsigned int cmd,
  							unsigned long arg)

  {
  	void __user *argp = (void __user *)arg;
  	int __user *p = argp;
  	int new_timeout;

  	static const struct watchdog_info ident = {

  		.options =		WDIOF_SETTIMEOUT |
  					WDIOF_KEEPALIVEPING |
  					WDIOF_MAGICCLOSE,
  		.firmware_version =	0,
  		.identity =		"Hardware Watchdog for TXx9",
  	};
  
  	switch (cmd) {

  	case WDIOC_GETSUPPORT:
  		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
  	case WDIOC_GETSTATUS:
  	case WDIOC_GETBOOTSTATUS:
  		return put_user(0, p);
  	case WDIOC_KEEPALIVE:
  		txx9wdt_ping();
  		return 0;
  	case WDIOC_SETTIMEOUT:
  		if (get_user(new_timeout, p))
  			return -EFAULT;
  		if (new_timeout < 1 || new_timeout > WD_MAX_TIMEOUT)
  			return -EINVAL;
  		timeout = new_timeout;
  		txx9wdt_stop();
  		txx9wdt_start();
  		/* Fall */
  	case WDIOC_GETTIMEOUT:
  		return put_user(timeout, p);

  	default:
  		return -ENOTTY;

  	}
  }

  static const struct file_operations txx9wdt_fops = {

  	.owner		=	THIS_MODULE,
  	.llseek		=	no_llseek,
  	.write		=	txx9wdt_write,
  	.unlocked_ioctl =	txx9wdt_ioctl,
  	.open		=	txx9wdt_open,
  	.release	=	txx9wdt_release,

  };
  
  static struct miscdevice txx9wdt_miscdev = {

  	.minor	=	WATCHDOG_MINOR,
  	.name	=	"watchdog",
  	.fops	=	&txx9wdt_fops,

  };

  static int __init txx9wdt_probe(struct platform_device *dev)
  {
  	struct resource *res;
  	int ret;
  
  	txx9_imclk = clk_get(NULL, "imbus_clk");
  	if (IS_ERR(txx9_imclk)) {
  		ret = PTR_ERR(txx9_imclk);
  		txx9_imclk = NULL;
  		goto exit;
  	}
  	ret = clk_enable(txx9_imclk);
  	if (ret) {
  		clk_put(txx9_imclk);
  		txx9_imclk = NULL;
  		goto exit;
  	}
  
  	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
  	if (!res)
  		goto exit_busy;

  	if (!devm_request_mem_region(&dev->dev, res->start, resource_size(res),

  				     "txx9wdt"))
  		goto exit_busy;

  	txx9wdt_reg = devm_ioremap(&dev->dev, res->start, resource_size(res));

  	if (!txx9wdt_reg)
  		goto exit_busy;

  	ret = misc_register(&txx9wdt_miscdev);
  	if (ret) {

  		goto exit;
  	}
  
  	printk(KERN_INFO "Hardware Watchdog Timer for TXx9: "
  	       "timeout=%d sec (max %ld) (nowayout= %d)
  ",
  	       timeout, WD_MAX_TIMEOUT, nowayout);
  
  	return 0;
  exit_busy:
  	ret = -EBUSY;
  exit:
  	if (txx9_imclk) {
  		clk_disable(txx9_imclk);
  		clk_put(txx9_imclk);
  	}
  	return ret;
  }
  
  static int __exit txx9wdt_remove(struct platform_device *dev)
  {
  	misc_deregister(&txx9wdt_miscdev);

  	clk_disable(txx9_imclk);
  	clk_put(txx9_imclk);
  	return 0;
  }

  static void txx9wdt_shutdown(struct platform_device *dev)
  {
  	txx9wdt_stop();
  }

  static struct platform_driver txx9wdt_driver = {
  	.remove = __exit_p(txx9wdt_remove),

  	.shutdown = txx9wdt_shutdown,

  	.driver = {
  		.name = "txx9wdt",
  		.owner = THIS_MODULE,
  	},
  };
  
  static int __init watchdog_init(void)
  {
  	return platform_driver_probe(&txx9wdt_driver, txx9wdt_probe);
  }
  
  static void __exit watchdog_exit(void)
  {
  	platform_driver_unregister(&txx9wdt_driver);
  }
  
  module_init(watchdog_init);
  module_exit(watchdog_exit);
  
  MODULE_DESCRIPTION("TXx9 Watchdog Driver");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

  MODULE_ALIAS("platform:txx9wdt");