text: // SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
  /*
   * Copyright (c) 2016 BayLibre, SAS.
   * Author: Neil Armstrong <narmstrong@baylibre.com>
   *
   */
  #include <linux/clk.h>
  #include <linux/err.h>
  #include <linux/io.h>
  #include <linux/module.h>
  #include <linux/of.h>
  #include <linux/platform_device.h>
  #include <linux/slab.h>
  #include <linux/types.h>
  #include <linux/watchdog.h>
  
  #define DEFAULT_TIMEOUT	30	/* seconds */
  
  #define GXBB_WDT_CTRL_REG			0x0
  #define GXBB_WDT_TCNT_REG			0x8
  #define GXBB_WDT_RSET_REG			0xc
  
  #define GXBB_WDT_CTRL_CLKDIV_EN			BIT(25)
  #define GXBB_WDT_CTRL_CLK_EN			BIT(24)
  #define GXBB_WDT_CTRL_EE_RESET			BIT(21)
  #define GXBB_WDT_CTRL_EN			BIT(18)
  #define GXBB_WDT_CTRL_DIV_MASK			(BIT(18) - 1)
  
  #define GXBB_WDT_TCNT_SETUP_MASK		(BIT(16) - 1)
  #define GXBB_WDT_TCNT_CNT_SHIFT			16
  
  struct meson_gxbb_wdt {
  	void __iomem *reg_base;
  	struct watchdog_device wdt_dev;
  	struct clk *clk;
  };
  
  static int meson_gxbb_wdt_start(struct watchdog_device *wdt_dev)
  {
  	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
  
  	writel(readl(data->reg_base + GXBB_WDT_CTRL_REG) | GXBB_WDT_CTRL_EN,
  	       data->reg_base + GXBB_WDT_CTRL_REG);
  
  	return 0;
  }
  
  static int meson_gxbb_wdt_stop(struct watchdog_device *wdt_dev)
  {
  	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
  
  	writel(readl(data->reg_base + GXBB_WDT_CTRL_REG) & ~GXBB_WDT_CTRL_EN,
  	       data->reg_base + GXBB_WDT_CTRL_REG);
  
  	return 0;
  }
  
  static int meson_gxbb_wdt_ping(struct watchdog_device *wdt_dev)
  {
  	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
  
  	writel(0, data->reg_base + GXBB_WDT_RSET_REG);
  
  	return 0;
  }
  
  static int meson_gxbb_wdt_set_timeout(struct watchdog_device *wdt_dev,
  				      unsigned int timeout)
  {
  	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
  	unsigned long tcnt = timeout * 1000;
  
  	if (tcnt > GXBB_WDT_TCNT_SETUP_MASK)
  		tcnt = GXBB_WDT_TCNT_SETUP_MASK;
  
  	wdt_dev->timeout = timeout;
  
  	meson_gxbb_wdt_ping(wdt_dev);
  
  	writel(tcnt, data->reg_base + GXBB_WDT_TCNT_REG);
  
  	return 0;
  }
  
  static unsigned int meson_gxbb_wdt_get_timeleft(struct watchdog_device *wdt_dev)
  {
  	struct meson_gxbb_wdt *data = watchdog_get_drvdata(wdt_dev);
  	unsigned long reg;
  
  	reg = readl(data->reg_base + GXBB_WDT_TCNT_REG);
  
  	return ((reg >> GXBB_WDT_TCNT_CNT_SHIFT) -
  		(reg & GXBB_WDT_TCNT_SETUP_MASK)) / 1000;
  }
  
  static const struct watchdog_ops meson_gxbb_wdt_ops = {
  	.start = meson_gxbb_wdt_start,
  	.stop = meson_gxbb_wdt_stop,
  	.ping = meson_gxbb_wdt_ping,
  	.set_timeout = meson_gxbb_wdt_set_timeout,
  	.get_timeleft = meson_gxbb_wdt_get_timeleft,
  };
  
  static const struct watchdog_info meson_gxbb_wdt_info = {
  	.identity = "Meson GXBB Watchdog",
  	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
  };
  
  static int __maybe_unused meson_gxbb_wdt_resume(struct device *dev)
  {
  	struct meson_gxbb_wdt *data = dev_get_drvdata(dev);
  
  	if (watchdog_active(&data->wdt_dev))
  		meson_gxbb_wdt_start(&data->wdt_dev);
  
  	return 0;
  }
  
  static int __maybe_unused meson_gxbb_wdt_suspend(struct device *dev)
  {
  	struct meson_gxbb_wdt *data = dev_get_drvdata(dev);
  
  	if (watchdog_active(&data->wdt_dev))
  		meson_gxbb_wdt_stop(&data->wdt_dev);
  
  	return 0;
  }
  
  static const struct dev_pm_ops meson_gxbb_wdt_pm_ops = {
  	SET_SYSTEM_SLEEP_PM_OPS(meson_gxbb_wdt_suspend, meson_gxbb_wdt_resume)
  };
  
  static const struct of_device_id meson_gxbb_wdt_dt_ids[] = {
  	 { .compatible = "amlogic,meson-gxbb-wdt", },
  	 { /* sentinel */ },
  };
  MODULE_DEVICE_TABLE(of, meson_gxbb_wdt_dt_ids);
  
  static void meson_clk_disable_unprepare(void *data)
  {
  	clk_disable_unprepare(data);
  }
  
  static int meson_gxbb_wdt_probe(struct platform_device *pdev)
  {
  	struct device *dev = &pdev->dev;
  	struct meson_gxbb_wdt *data;
  	int ret;
  
  	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
  	if (!data)
  		return -ENOMEM;
  
  	data->reg_base = devm_platform_ioremap_resource(pdev, 0);
  	if (IS_ERR(data->reg_base))
  		return PTR_ERR(data->reg_base);
  
  	data->clk = devm_clk_get(dev, NULL);
  	if (IS_ERR(data->clk))
  		return PTR_ERR(data->clk);
  
  	ret = clk_prepare_enable(data->clk);
  	if (ret)
  		return ret;
  	ret = devm_add_action_or_reset(dev, meson_clk_disable_unprepare,
  				       data->clk);
  	if (ret)
  		return ret;
  
  	platform_set_drvdata(pdev, data);
  
  	data->wdt_dev.parent = dev;
  	data->wdt_dev.info = &meson_gxbb_wdt_info;
  	data->wdt_dev.ops = &meson_gxbb_wdt_ops;
  	data->wdt_dev.max_hw_heartbeat_ms = GXBB_WDT_TCNT_SETUP_MASK;
  	data->wdt_dev.min_timeout = 1;
  	data->wdt_dev.timeout = DEFAULT_TIMEOUT;
  	watchdog_set_drvdata(&data->wdt_dev, data);
  
  	/* Setup with 1ms timebase */
  	writel(((clk_get_rate(data->clk) / 1000) & GXBB_WDT_CTRL_DIV_MASK) |
  		GXBB_WDT_CTRL_EE_RESET |
  		GXBB_WDT_CTRL_CLK_EN |
  		GXBB_WDT_CTRL_CLKDIV_EN,
  		data->reg_base + GXBB_WDT_CTRL_REG);
  
  	meson_gxbb_wdt_set_timeout(&data->wdt_dev, data->wdt_dev.timeout);
  
  	watchdog_stop_on_reboot(&data->wdt_dev);
  	return devm_watchdog_register_device(dev, &data->wdt_dev);
  }
  
  static struct platform_driver meson_gxbb_wdt_driver = {
  	.probe	= meson_gxbb_wdt_probe,
  	.driver = {
  		.name = "meson-gxbb-wdt",
  		.pm = &meson_gxbb_wdt_pm_ops,
  		.of_match_table	= meson_gxbb_wdt_dt_ids,
  	},
  };
  
  module_platform_driver(meson_gxbb_wdt_driver);
  
  MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
  MODULE_DESCRIPTION("Amlogic Meson GXBB Watchdog timer driver");
  MODULE_LICENSE("Dual BSD/GPL");
  