/*
   * drivers/char/watchdog/davinci_wdt.c
   *
   * Watchdog driver for DaVinci DM644x/DM646x processors
   *

   * Copyright (C) 2006-2013 Texas Instruments.

   *
   * 2007 (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.
   */
  
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/types.h>
  #include <linux/kernel.h>

  #include <linux/watchdog.h>

  #include <linux/platform_device.h>

  #include <linux/io.h>

  #include <linux/device.h>

  #include <linux/clk.h>

  #include <linux/err.h>

  
  #define MODULE_NAME "DAVINCI-WDT: "
  
  #define DEFAULT_HEARTBEAT 60
  #define MAX_HEARTBEAT     600	/* really the max margin is 264/27MHz*/
  
  /* Timer register set definition */
  #define PID12	(0x0)
  #define EMUMGT	(0x4)
  #define TIM12	(0x10)
  #define TIM34	(0x14)
  #define PRD12	(0x18)
  #define PRD34	(0x1C)
  #define TCR	(0x20)
  #define TGCR	(0x24)
  #define WDTCR	(0x28)
  
  /* TCR bit definitions */
  #define ENAMODE12_DISABLED	(0 << 6)
  #define ENAMODE12_ONESHOT	(1 << 6)
  #define ENAMODE12_PERIODIC	(2 << 6)
  
  /* TGCR bit definitions */
  #define TIM12RS_UNRESET		(1 << 0)
  #define TIM34RS_UNRESET		(1 << 1)
  #define TIMMODE_64BIT_WDOG      (2 << 2)
  
  /* WDTCR bit definitions */
  #define WDEN			(1 << 14)
  #define WDFLAG			(1 << 15)
  #define WDKEY_SEQ0		(0xa5c6 << 16)
  #define WDKEY_SEQ1		(0xda7e << 16)

  static int heartbeat;

  
  /*
   * struct to hold data for each WDT device
   * @base - base io address of WD device
   * @clk - source clock of WDT
   * @wdd - hold watchdog device as is in WDT core
   */
  struct davinci_wdt_device {
  	void __iomem		*base;
  	struct clk		*clk;
  	struct watchdog_device	wdd;
  };

  static int davinci_wdt_start(struct watchdog_device *wdd)

  {
  	u32 tgcr;
  	u32 timer_margin;

  	unsigned long wdt_freq;

  	struct davinci_wdt_device *davinci_wdt = watchdog_get_drvdata(wdd);

  	wdt_freq = clk_get_rate(davinci_wdt->clk);

  	/* disable, internal clock source */

  	iowrite32(0, davinci_wdt->base + TCR);

  	/* reset timer, set mode to 64-bit watchdog, and unreset */

  	iowrite32(0, davinci_wdt->base + TGCR);

  	tgcr = TIMMODE_64BIT_WDOG | TIM12RS_UNRESET | TIM34RS_UNRESET;

  	iowrite32(tgcr, davinci_wdt->base + TGCR);

  	/* clear counter regs */

  	iowrite32(0, davinci_wdt->base + TIM12);
  	iowrite32(0, davinci_wdt->base + TIM34);

  	/* set timeout period */

  	timer_margin = (((u64)wdd->timeout * wdt_freq) & 0xffffffff);

  	iowrite32(timer_margin, davinci_wdt->base + PRD12);

  	timer_margin = (((u64)wdd->timeout * wdt_freq) >> 32);

  	iowrite32(timer_margin, davinci_wdt->base + PRD34);

  	/* enable run continuously */

  	iowrite32(ENAMODE12_PERIODIC, davinci_wdt->base + TCR);

  	/* Once the WDT is in pre-active state write to
  	 * TIM12, TIM34, PRD12, PRD34, TCR, TGCR, WDTCR are
  	 * write protected (except for the WDKEY field)
  	 */
  	/* put watchdog in pre-active state */

  	iowrite32(WDKEY_SEQ0 | WDEN, davinci_wdt->base + WDTCR);

  	/* put watchdog in active state */

  	iowrite32(WDKEY_SEQ1 | WDEN, davinci_wdt->base + WDTCR);

  	return 0;

  }

  static int davinci_wdt_ping(struct watchdog_device *wdd)

  {

  	struct davinci_wdt_device *davinci_wdt = watchdog_get_drvdata(wdd);

  	/* put watchdog in service state */

  	iowrite32(WDKEY_SEQ0, davinci_wdt->base + WDTCR);

  	/* put watchdog in active state */

  	iowrite32(WDKEY_SEQ1, davinci_wdt->base + WDTCR);

  	return 0;

  }

  static unsigned int davinci_wdt_get_timeleft(struct watchdog_device *wdd)
  {
  	u64 timer_counter;
  	unsigned long freq;
  	u32 val;
  	struct davinci_wdt_device *davinci_wdt = watchdog_get_drvdata(wdd);
  
  	/* if timeout has occured then return 0 */
  	val = ioread32(davinci_wdt->base + WDTCR);
  	if (val & WDFLAG)
  		return 0;
  
  	freq = clk_get_rate(davinci_wdt->clk);
  
  	if (!freq)
  		return 0;
  
  	timer_counter = ioread32(davinci_wdt->base + TIM12);
  	timer_counter |= ((u64)ioread32(davinci_wdt->base + TIM34) << 32);
  
  	do_div(timer_counter, freq);
  
  	return wdd->timeout - timer_counter;
  }

  static const struct watchdog_info davinci_wdt_info = {

  	.options = WDIOF_KEEPALIVEPING,

  	.identity = "DaVinci/Keystone Watchdog",

  };

  static const struct watchdog_ops davinci_wdt_ops = {
  	.owner		= THIS_MODULE,
  	.start		= davinci_wdt_start,
  	.stop		= davinci_wdt_ping,
  	.ping		= davinci_wdt_ping,

  	.get_timeleft	= davinci_wdt_get_timeleft,

  };

  static int davinci_wdt_probe(struct platform_device *pdev)

  {

  	int ret = 0;

  	struct device *dev = &pdev->dev;

  	struct resource  *wdt_mem;

  	struct watchdog_device *wdd;

  	struct davinci_wdt_device *davinci_wdt;
  
  	davinci_wdt = devm_kzalloc(dev, sizeof(*davinci_wdt), GFP_KERNEL);
  	if (!davinci_wdt)
  		return -ENOMEM;

  	davinci_wdt->clk = devm_clk_get(dev, NULL);
  	if (WARN_ON(IS_ERR(davinci_wdt->clk)))
  		return PTR_ERR(davinci_wdt->clk);

  	clk_prepare_enable(davinci_wdt->clk);

  	platform_set_drvdata(pdev, davinci_wdt);
  
  	wdd			= &davinci_wdt->wdd;

  	wdd->info		= &davinci_wdt_info;
  	wdd->ops		= &davinci_wdt_ops;
  	wdd->min_timeout	= 1;
  	wdd->max_timeout	= MAX_HEARTBEAT;
  	wdd->timeout		= DEFAULT_HEARTBEAT;

  	wdd->parent		= &pdev->dev;

  
  	watchdog_init_timeout(wdd, heartbeat, dev);
  
  	dev_info(dev, "heartbeat %d sec
  ", wdd->timeout);

  	watchdog_set_drvdata(wdd, davinci_wdt);

  	watchdog_set_nowayout(wdd, 1);

  	wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);

  	davinci_wdt->base = devm_ioremap_resource(dev, wdt_mem);
  	if (IS_ERR(davinci_wdt->base))
  		return PTR_ERR(davinci_wdt->base);

  	ret = watchdog_register_device(wdd);
  	if (ret < 0)
  		dev_err(dev, "cannot register watchdog device
  ");

  
  	return ret;
  }

  static int davinci_wdt_remove(struct platform_device *pdev)

  {

  	struct davinci_wdt_device *davinci_wdt = platform_get_drvdata(pdev);
  
  	watchdog_unregister_device(&davinci_wdt->wdd);
  	clk_disable_unprepare(davinci_wdt->clk);

  	return 0;
  }

  static const struct of_device_id davinci_wdt_of_match[] = {
  	{ .compatible = "ti,davinci-wdt", },
  	{},
  };
  MODULE_DEVICE_TABLE(of, davinci_wdt_of_match);

  static struct platform_driver platform_wdt_driver = {
  	.driver = {

  		.name = "davinci-wdt",

  		.of_match_table = davinci_wdt_of_match,

  	},
  	.probe = davinci_wdt_probe,

  	.remove = davinci_wdt_remove,

  };

  module_platform_driver(platform_wdt_driver);

  
  MODULE_AUTHOR("Texas Instruments");
  MODULE_DESCRIPTION("DaVinci Watchdog Driver");
  
  module_param(heartbeat, int, 0);
  MODULE_PARM_DESC(heartbeat,
  		 "Watchdog heartbeat period in seconds from 1 to "
  		 __MODULE_STRING(MAX_HEARTBEAT) ", default "
  		 __MODULE_STRING(DEFAULT_HEARTBEAT));
  
  MODULE_LICENSE("GPL");

  MODULE_ALIAS("platform:davinci-wdt");