/*
   * 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.
   */

  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/types.h>

  #include <linux/watchdog.h>

  #include <linux/init.h>

  #include <linux/platform_device.h>
  #include <linux/clk.h>
  #include <linux/err.h>
  #include <linux/io.h>
  #include <asm/txx9tmr.h>

  #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)

  #define TIMER_MARGIN	60		/* Default is 60 seconds */

  static unsigned int timeout = TIMER_MARGIN;	/* in seconds */
  module_param(timeout, uint, 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 bool nowayout = WATCHDOG_NOWAYOUT;
  module_param(nowayout, bool, 0);

  MODULE_PARM_DESC(nowayout,
  	"Watchdog cannot be stopped once started "
  	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

  static struct txx9_tmr_reg __iomem *txx9wdt_reg;
  static struct clk *txx9_imclk;

  static DEFINE_SPINLOCK(txx9_lock);

  static int txx9wdt_ping(struct watchdog_device *wdt_dev)

  {

  	spin_lock(&txx9_lock);

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

  	spin_unlock(&txx9_lock);

  	return 0;

  }

  static int txx9wdt_start(struct watchdog_device *wdt_dev)

  {

  	spin_lock(&txx9_lock);

  	__raw_writel(WD_TIMER_CLK * wdt_dev->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);

  	return 0;

  }

  static int txx9wdt_stop(struct watchdog_device *wdt_dev)

  {

  	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);

  	return 0;
  }

  static int txx9wdt_set_timeout(struct watchdog_device *wdt_dev,
  			       unsigned int new_timeout)

  {

  	wdt_dev->timeout = new_timeout;

  	txx9wdt_stop(wdt_dev);
  	txx9wdt_start(wdt_dev);
  	return 0;

  }

  static const struct watchdog_info txx9wdt_info = {
  	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
  	.identity = "Hardware Watchdog for TXx9",
  };

  static const struct watchdog_ops txx9wdt_ops = {
  	.owner = THIS_MODULE,
  	.start = txx9wdt_start,
  	.stop = txx9wdt_stop,
  	.ping = txx9wdt_ping,
  	.set_timeout = txx9wdt_set_timeout,

  };

  static struct watchdog_device txx9wdt = {
  	.info = &txx9wdt_info,
  	.ops = &txx9wdt_ops,

  };

  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_prepare_enable(txx9_imclk);

  	if (ret) {
  		clk_put(txx9_imclk);
  		txx9_imclk = NULL;
  		goto exit;
  	}
  
  	res = platform_get_resource(dev, IORESOURCE_MEM, 0);

  	txx9wdt_reg = devm_ioremap_resource(&dev->dev, res);
  	if (IS_ERR(txx9wdt_reg)) {
  		ret = PTR_ERR(txx9wdt_reg);

  		goto exit;
  	}

  	if (timeout < 1 || timeout > WD_MAX_TIMEOUT)
  		timeout = TIMER_MARGIN;
  	txx9wdt.timeout = timeout;

  	txx9wdt.min_timeout = 1;
  	txx9wdt.max_timeout = WD_MAX_TIMEOUT;

  	txx9wdt.parent = &dev->dev;

  	watchdog_set_nowayout(&txx9wdt, nowayout);
  
  	ret = watchdog_register_device(&txx9wdt);
  	if (ret)
  		goto exit;

  	pr_info("Hardware Watchdog Timer: timeout=%d sec (max %ld) (nowayout= %d)
  ",
  		timeout, WD_MAX_TIMEOUT, nowayout);

  
  	return 0;

  exit:
  	if (txx9_imclk) {

  		clk_disable_unprepare(txx9_imclk);

  		clk_put(txx9_imclk);
  	}
  	return ret;
  }
  
  static int __exit txx9wdt_remove(struct platform_device *dev)
  {

  	watchdog_unregister_device(&txx9wdt);

  	clk_disable_unprepare(txx9_imclk);

  	clk_put(txx9_imclk);
  	return 0;
  }

  static void txx9wdt_shutdown(struct platform_device *dev)
  {

  	txx9wdt_stop(&txx9wdt);

  }

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

  	.shutdown = txx9wdt_shutdown,

  	.driver = {
  		.name = "txx9wdt",

  	},
  };

  module_platform_driver_probe(txx9wdt_driver, txx9wdt_probe);

  
  MODULE_DESCRIPTION("TXx9 Watchdog Driver");
  MODULE_LICENSE("GPL");

  MODULE_ALIAS("platform:txx9wdt");