// SPDX-License-Identifier: GPL-2.0-only

  /*
   * Watchdog driver for CSR Atlas7
   *
   * Copyright (c) 2015 Cambridge Silicon Radio Limited, a CSR plc group company.

   */
  
  #include <linux/clk.h>
  #include <linux/io.h>
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/of.h>
  #include <linux/platform_device.h>
  #include <linux/watchdog.h>
  
  #define ATLAS7_TIMER_WDT_INDEX		5
  #define ATLAS7_WDT_DEFAULT_TIMEOUT	20
  
  #define ATLAS7_WDT_CNT_CTRL	(0 + 4 * ATLAS7_TIMER_WDT_INDEX)
  #define ATLAS7_WDT_CNT_MATCH	(0x18 + 4 * ATLAS7_TIMER_WDT_INDEX)
  #define ATLAS7_WDT_CNT		(0x48 +  4 * ATLAS7_TIMER_WDT_INDEX)
  #define ATLAS7_WDT_CNT_EN	(BIT(0) | BIT(1))
  #define ATLAS7_WDT_EN		0x64
  
  static unsigned int timeout = ATLAS7_WDT_DEFAULT_TIMEOUT;
  static bool nowayout = WATCHDOG_NOWAYOUT;
  
  module_param(timeout, uint, 0);
  module_param(nowayout, bool, 0);
  
  MODULE_PARM_DESC(timeout, "Default watchdog timeout (in seconds)");
  MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  			__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  
  struct atlas7_wdog {
  	struct device *dev;
  	void __iomem *base;
  	unsigned long tick_rate;
  	struct clk *clk;
  };
  
  static unsigned int atlas7_wdt_gettimeleft(struct watchdog_device *wdd)
  {
  	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
  	u32 counter, match, delta;
  
  	counter = readl(wdt->base + ATLAS7_WDT_CNT);
  	match = readl(wdt->base + ATLAS7_WDT_CNT_MATCH);
  	delta = match - counter;
  
  	return  delta / wdt->tick_rate;
  }
  
  static int atlas7_wdt_ping(struct watchdog_device *wdd)
  {
  	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
  	u32 counter, match, delta;
  
  	counter = readl(wdt->base + ATLAS7_WDT_CNT);
  	delta = wdd->timeout * wdt->tick_rate;
  	match = counter + delta;
  
  	writel(match, wdt->base + ATLAS7_WDT_CNT_MATCH);
  
  	return 0;
  }
  
  static int atlas7_wdt_enable(struct watchdog_device *wdd)
  {
  	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
  
  	atlas7_wdt_ping(wdd);
  
  	writel(readl(wdt->base + ATLAS7_WDT_CNT_CTRL) | ATLAS7_WDT_CNT_EN,
  	      wdt->base + ATLAS7_WDT_CNT_CTRL);
  	writel(1, wdt->base + ATLAS7_WDT_EN);
  
  	return 0;
  }
  
  static int atlas7_wdt_disable(struct watchdog_device *wdd)
  {
  	struct atlas7_wdog *wdt = watchdog_get_drvdata(wdd);
  
  	writel(0, wdt->base + ATLAS7_WDT_EN);
  	writel(readl(wdt->base + ATLAS7_WDT_CNT_CTRL) & ~ATLAS7_WDT_CNT_EN,
  	      wdt->base + ATLAS7_WDT_CNT_CTRL);
  
  	return 0;
  }
  
  static int atlas7_wdt_settimeout(struct watchdog_device *wdd, unsigned int to)
  {
  	wdd->timeout = to;
  
  	return 0;
  }
  
  #define OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
  
  static const struct watchdog_info atlas7_wdt_ident = {
  	.options = OPTIONS,
  	.firmware_version = 0,
  	.identity = "atlas7 Watchdog",
  };

  static const struct watchdog_ops atlas7_wdt_ops = {

  	.owner = THIS_MODULE,
  	.start = atlas7_wdt_enable,
  	.stop = atlas7_wdt_disable,
  	.get_timeleft = atlas7_wdt_gettimeleft,
  	.ping = atlas7_wdt_ping,
  	.set_timeout = atlas7_wdt_settimeout,
  };
  
  static struct watchdog_device atlas7_wdd = {
  	.info = &atlas7_wdt_ident,
  	.ops = &atlas7_wdt_ops,
  	.timeout = ATLAS7_WDT_DEFAULT_TIMEOUT,
  };
  
  static const struct of_device_id atlas7_wdt_ids[] = {
  	{ .compatible = "sirf,atlas7-tick"},
  	{}
  };

  static void atlas7_clk_disable_unprepare(void *data)
  {
  	clk_disable_unprepare(data);
  }

  static int atlas7_wdt_probe(struct platform_device *pdev)
  {

  	struct device *dev = &pdev->dev;

  	struct atlas7_wdog *wdt;

  	struct clk *clk;
  	int ret;

  	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);

  	if (!wdt)
  		return -ENOMEM;

  	wdt->base = devm_platform_ioremap_resource(pdev, 0);

  	if (IS_ERR(wdt->base))
  		return PTR_ERR(wdt->base);

  	clk = devm_clk_get(dev, NULL);

  	if (IS_ERR(clk))
  		return PTR_ERR(clk);
  	ret = clk_prepare_enable(clk);
  	if (ret) {

  		dev_err(dev, "clk enable failed
  ");
  		return ret;

  	}

  	ret = devm_add_action_or_reset(dev, atlas7_clk_disable_unprepare, clk);
  	if (ret)
  		return ret;

  
  	/* disable watchdog hardware */
  	writel(0, wdt->base + ATLAS7_WDT_CNT_CTRL);
  
  	wdt->tick_rate = clk_get_rate(clk);

  	if (!wdt->tick_rate)
  		return -EINVAL;

  	wdt->clk = clk;
  	atlas7_wdd.min_timeout = 1;
  	atlas7_wdd.max_timeout = UINT_MAX / wdt->tick_rate;

  	watchdog_init_timeout(&atlas7_wdd, 0, dev);

  	watchdog_set_nowayout(&atlas7_wdd, nowayout);
  
  	watchdog_set_drvdata(&atlas7_wdd, wdt);
  	platform_set_drvdata(pdev, &atlas7_wdd);

  	watchdog_stop_on_reboot(&atlas7_wdd);
  	watchdog_stop_on_unregister(&atlas7_wdd);
  	return devm_watchdog_register_device(dev, &atlas7_wdd);

  }
  
  static int __maybe_unused atlas7_wdt_suspend(struct device *dev)
  {
  	/*
  	 * NOTE:timer controller registers settings are saved
  	 * and restored back by the timer-atlas7.c
  	 */
  	return 0;
  }
  
  static int __maybe_unused atlas7_wdt_resume(struct device *dev)
  {
  	struct watchdog_device *wdd = dev_get_drvdata(dev);
  
  	/*
  	 * NOTE: Since timer controller registers settings are saved
  	 * and restored back by the timer-atlas7.c, so we need not
  	 * update WD settings except refreshing timeout.
  	 */
  	atlas7_wdt_ping(wdd);
  
  	return 0;
  }
  
  static SIMPLE_DEV_PM_OPS(atlas7_wdt_pm_ops,
  		atlas7_wdt_suspend, atlas7_wdt_resume);
  
  MODULE_DEVICE_TABLE(of, atlas7_wdt_ids);
  
  static struct platform_driver atlas7_wdt_driver = {
  	.driver = {
  		.name = "atlas7-wdt",
  		.pm = &atlas7_wdt_pm_ops,
  		.of_match_table	= atlas7_wdt_ids,
  	},
  	.probe = atlas7_wdt_probe,

  };
  module_platform_driver(atlas7_wdt_driver);
  
  MODULE_DESCRIPTION("CSRatlas7 watchdog driver");
  MODULE_AUTHOR("Guo Zeng <Guo.Zeng@csr.com>");
  MODULE_LICENSE("GPL v2");
  MODULE_ALIAS("platform:atlas7-wdt");