// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   *  Copyright (C) 2010, Paul Cercueil <paul@crapouillou.net>
   *  JZ4740 Watchdog driver

   */

  #include <linux/mfd/ingenic-tcu.h>

  #include <linux/mfd/syscon.h>

  #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/slab.h>

  #include <linux/err.h>

  #include <linux/of.h>

  #include <linux/regmap.h>

  #define DEFAULT_HEARTBEAT 5
  #define MAX_HEARTBEAT     2048

  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 unsigned int heartbeat = DEFAULT_HEARTBEAT;
  module_param(heartbeat, uint, 0);
  MODULE_PARM_DESC(heartbeat,
  		"Watchdog heartbeat period in seconds from 1 to "
  		__MODULE_STRING(MAX_HEARTBEAT) ", default "
  		__MODULE_STRING(DEFAULT_HEARTBEAT));

  struct jz4740_wdt_drvdata {
  	struct watchdog_device wdt;

  	struct regmap *map;

  	struct clk *clk;
  	unsigned long clk_rate;

  };

  static int jz4740_wdt_ping(struct watchdog_device *wdt_dev)

  {

  	struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);

  	regmap_write(drvdata->map, TCU_REG_WDT_TCNT, 0);

  	return 0;

  }

  static int jz4740_wdt_set_timeout(struct watchdog_device *wdt_dev,
  				    unsigned int new_timeout)

  {

  	struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);

  	u16 timeout_value = (u16)(drvdata->clk_rate * new_timeout);

  	unsigned int tcer;

  	regmap_read(drvdata->map, TCU_REG_WDT_TCER, &tcer);
  	regmap_write(drvdata->map, TCU_REG_WDT_TCER, 0);

  	regmap_write(drvdata->map, TCU_REG_WDT_TDR, timeout_value);
  	regmap_write(drvdata->map, TCU_REG_WDT_TCNT, 0);

  	if (tcer & TCU_WDT_TCER_TCEN)

  		regmap_write(drvdata->map, TCU_REG_WDT_TCER, TCU_WDT_TCER_TCEN);

  	wdt_dev->timeout = new_timeout;

  	return 0;

  }

  static int jz4740_wdt_start(struct watchdog_device *wdt_dev)

  {

  	struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);

  	unsigned int tcer;

  	int ret;

  	ret = clk_prepare_enable(drvdata->clk);
  	if (ret)
  		return ret;

  	regmap_read(drvdata->map, TCU_REG_WDT_TCER, &tcer);

  	jz4740_wdt_set_timeout(wdt_dev, wdt_dev->timeout);

  	/* Start watchdog if it wasn't started already */
  	if (!(tcer & TCU_WDT_TCER_TCEN))

  		regmap_write(drvdata->map, TCU_REG_WDT_TCER, TCU_WDT_TCER_TCEN);

  	return 0;

  }

  static int jz4740_wdt_stop(struct watchdog_device *wdt_dev)

  {

  	struct jz4740_wdt_drvdata *drvdata = watchdog_get_drvdata(wdt_dev);

  	regmap_write(drvdata->map, TCU_REG_WDT_TCER, 0);

  	clk_disable_unprepare(drvdata->clk);

  	return 0;

  }

  static int jz4740_wdt_restart(struct watchdog_device *wdt_dev,
  			      unsigned long action, void *data)
  {
  	wdt_dev->timeout = 0;
  	jz4740_wdt_start(wdt_dev);
  	return 0;
  }

  static const struct watchdog_info jz4740_wdt_info = {
  	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,

  	.identity = "jz4740 Watchdog",
  };

  static const struct watchdog_ops jz4740_wdt_ops = {

  	.owner = THIS_MODULE,

  	.start = jz4740_wdt_start,
  	.stop = jz4740_wdt_stop,
  	.ping = jz4740_wdt_ping,
  	.set_timeout = jz4740_wdt_set_timeout,

  	.restart = jz4740_wdt_restart,

  };

  #ifdef CONFIG_OF
  static const struct of_device_id jz4740_wdt_of_matches[] = {
  	{ .compatible = "ingenic,jz4740-watchdog", },

  	{ .compatible = "ingenic,jz4780-watchdog", },

  	{ /* sentinel */ }
  };

  MODULE_DEVICE_TABLE(of, jz4740_wdt_of_matches);

  #endif

  static int jz4740_wdt_probe(struct platform_device *pdev)

  {

  	struct device *dev = &pdev->dev;

  	struct jz4740_wdt_drvdata *drvdata;
  	struct watchdog_device *jz4740_wdt;

  	long rate;
  	int ret;

  	drvdata = devm_kzalloc(dev, sizeof(struct jz4740_wdt_drvdata),

  			       GFP_KERNEL);

  	if (!drvdata)

  		return -ENOMEM;

  	drvdata->clk = devm_clk_get(&pdev->dev, "wdt");
  	if (IS_ERR(drvdata->clk)) {
  		dev_err(&pdev->dev, "cannot find WDT clock
  ");
  		return PTR_ERR(drvdata->clk);
  	}
  
  	/* Set smallest clock possible */
  	rate = clk_round_rate(drvdata->clk, 1);
  	if (rate < 0)
  		return rate;
  
  	ret = clk_set_rate(drvdata->clk, rate);
  	if (ret)
  		return ret;

  	drvdata->clk_rate = rate;

  	jz4740_wdt = &drvdata->wdt;
  	jz4740_wdt->info = &jz4740_wdt_info;
  	jz4740_wdt->ops = &jz4740_wdt_ops;

  	jz4740_wdt->min_timeout = 1;

  	jz4740_wdt->max_timeout = 0xffff / rate;
  	jz4740_wdt->timeout = clamp(heartbeat,
  				    jz4740_wdt->min_timeout,
  				    jz4740_wdt->max_timeout);

  	jz4740_wdt->parent = dev;

  	watchdog_set_nowayout(jz4740_wdt, nowayout);
  	watchdog_set_drvdata(jz4740_wdt, drvdata);

  	drvdata->map = device_node_to_regmap(dev->parent->of_node);
  	if (!drvdata->map) {
  		dev_err(dev, "regmap not found
  ");
  		return -EINVAL;
  	}

  	return devm_watchdog_register_device(dev, &drvdata->wdt);

  }

  static struct platform_driver jz4740_wdt_driver = {
  	.probe = jz4740_wdt_probe,

  	.driver = {
  		.name = "jz4740-wdt",

  		.of_match_table = of_match_ptr(jz4740_wdt_of_matches),

  	},
  };

  module_platform_driver(jz4740_wdt_driver);

  
  MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
  MODULE_DESCRIPTION("jz4740 Watchdog Driver");

  MODULE_LICENSE("GPL");

  MODULE_ALIAS("platform:jz4740-wdt");