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

  /*
   *      sunxi Watchdog Driver
   *
   *      Copyright (c) 2013 Carlo Caione
   *                    2012 Henrik Nordstrom
   *

   *      Based on xen_wdt.c
   *      (c) Copyright 2010 Novell, Inc.
   */
  
  #include <linux/clk.h>

  #include <linux/delay.h>

  #include <linux/err.h>
  #include <linux/init.h>
  #include <linux/io.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/of.h>

  #include <linux/of_device.h>

  #include <linux/platform_device.h>
  #include <linux/types.h>
  #include <linux/watchdog.h>
  
  #define WDT_MAX_TIMEOUT         16
  #define WDT_MIN_TIMEOUT         1

  #define WDT_TIMEOUT_MASK        0x0F

  #define WDT_CTRL_RELOAD         ((1 << 0) | (0x0a57 << 1))

  #define WDT_MODE_EN             (1 << 0)

  
  #define DRV_NAME		"sunxi-wdt"
  #define DRV_VERSION		"1.0"
  
  static bool nowayout = WATCHDOG_NOWAYOUT;

  static unsigned int timeout;

  /*
   * This structure stores the register offsets for different variants
   * of Allwinner's watchdog hardware.
   */
  struct sunxi_wdt_reg {
  	u8 wdt_ctrl;
  	u8 wdt_cfg;
  	u8 wdt_mode;
  	u8 wdt_timeout_shift;
  	u8 wdt_reset_mask;
  	u8 wdt_reset_val;
  };

  struct sunxi_wdt_dev {
  	struct watchdog_device wdt_dev;
  	void __iomem *wdt_base;

  	const struct sunxi_wdt_reg *wdt_regs;

  };
  
  /*
   * wdt_timeout_map maps the watchdog timer interval value in seconds to

   * the value of the register WDT_MODE at bits .wdt_timeout_shift ~ +3

   *
   * [timeout seconds] = register value
   *
   */
  
  static const int wdt_timeout_map[] = {

  	[1] = 0x1,  /* 1s  */
  	[2] = 0x2,  /* 2s  */
  	[3] = 0x3,  /* 3s  */
  	[4] = 0x4,  /* 4s  */
  	[5] = 0x5,  /* 5s  */
  	[6] = 0x6,  /* 6s  */
  	[8] = 0x7,  /* 8s  */
  	[10] = 0x8, /* 10s */
  	[12] = 0x9, /* 12s */
  	[14] = 0xA, /* 14s */
  	[16] = 0xB, /* 16s */

  };

  static int sunxi_wdt_restart(struct watchdog_device *wdt_dev,
  			     unsigned long action, void *data)

  {

  	struct sunxi_wdt_dev *sunxi_wdt = watchdog_get_drvdata(wdt_dev);

  	void __iomem *wdt_base = sunxi_wdt->wdt_base;

  	const struct sunxi_wdt_reg *regs = sunxi_wdt->wdt_regs;
  	u32 val;
  
  	/* Set system reset function */
  	val = readl(wdt_base + regs->wdt_cfg);
  	val &= ~(regs->wdt_reset_mask);
  	val |= regs->wdt_reset_val;
  	writel(val, wdt_base + regs->wdt_cfg);

  	/* Set lowest timeout and enable watchdog */
  	val = readl(wdt_base + regs->wdt_mode);
  	val &= ~(WDT_TIMEOUT_MASK << regs->wdt_timeout_shift);
  	val |= WDT_MODE_EN;
  	writel(val, wdt_base + regs->wdt_mode);

  
  	/*
  	 * Restart the watchdog. The default (and lowest) interval
  	 * value for the watchdog is 0.5s.
  	 */

  	writel(WDT_CTRL_RELOAD, wdt_base + regs->wdt_ctrl);

  
  	while (1) {
  		mdelay(5);

  		val = readl(wdt_base + regs->wdt_mode);
  		val |= WDT_MODE_EN;
  		writel(val, wdt_base + regs->wdt_mode);

  	}

  	return 0;

  }

  static int sunxi_wdt_ping(struct watchdog_device *wdt_dev)
  {
  	struct sunxi_wdt_dev *sunxi_wdt = watchdog_get_drvdata(wdt_dev);
  	void __iomem *wdt_base = sunxi_wdt->wdt_base;

  	const struct sunxi_wdt_reg *regs = sunxi_wdt->wdt_regs;

  	writel(WDT_CTRL_RELOAD, wdt_base + regs->wdt_ctrl);

  
  	return 0;
  }
  
  static int sunxi_wdt_set_timeout(struct watchdog_device *wdt_dev,
  		unsigned int timeout)
  {
  	struct sunxi_wdt_dev *sunxi_wdt = watchdog_get_drvdata(wdt_dev);
  	void __iomem *wdt_base = sunxi_wdt->wdt_base;

  	const struct sunxi_wdt_reg *regs = sunxi_wdt->wdt_regs;

  	u32 reg;
  
  	if (wdt_timeout_map[timeout] == 0)
  		timeout++;
  
  	sunxi_wdt->wdt_dev.timeout = timeout;

  	reg = readl(wdt_base + regs->wdt_mode);
  	reg &= ~(WDT_TIMEOUT_MASK << regs->wdt_timeout_shift);
  	reg |= wdt_timeout_map[timeout] << regs->wdt_timeout_shift;
  	writel(reg, wdt_base + regs->wdt_mode);

  
  	sunxi_wdt_ping(wdt_dev);
  
  	return 0;
  }
  
  static int sunxi_wdt_stop(struct watchdog_device *wdt_dev)
  {
  	struct sunxi_wdt_dev *sunxi_wdt = watchdog_get_drvdata(wdt_dev);
  	void __iomem *wdt_base = sunxi_wdt->wdt_base;

  	const struct sunxi_wdt_reg *regs = sunxi_wdt->wdt_regs;

  	writel(0, wdt_base + regs->wdt_mode);

  
  	return 0;
  }
  
  static int sunxi_wdt_start(struct watchdog_device *wdt_dev)
  {
  	u32 reg;
  	struct sunxi_wdt_dev *sunxi_wdt = watchdog_get_drvdata(wdt_dev);
  	void __iomem *wdt_base = sunxi_wdt->wdt_base;

  	const struct sunxi_wdt_reg *regs = sunxi_wdt->wdt_regs;

  	int ret;
  
  	ret = sunxi_wdt_set_timeout(&sunxi_wdt->wdt_dev,
  			sunxi_wdt->wdt_dev.timeout);
  	if (ret < 0)
  		return ret;

  	/* Set system reset function */
  	reg = readl(wdt_base + regs->wdt_cfg);
  	reg &= ~(regs->wdt_reset_mask);

  	reg |= regs->wdt_reset_val;

  	writel(reg, wdt_base + regs->wdt_cfg);
  
  	/* Enable watchdog */
  	reg = readl(wdt_base + regs->wdt_mode);
  	reg |= WDT_MODE_EN;
  	writel(reg, wdt_base + regs->wdt_mode);

  
  	return 0;
  }
  
  static const struct watchdog_info sunxi_wdt_info = {
  	.identity	= DRV_NAME,
  	.options	= WDIOF_SETTIMEOUT |
  			  WDIOF_KEEPALIVEPING |
  			  WDIOF_MAGICCLOSE,
  };
  
  static const struct watchdog_ops sunxi_wdt_ops = {
  	.owner		= THIS_MODULE,
  	.start		= sunxi_wdt_start,
  	.stop		= sunxi_wdt_stop,
  	.ping		= sunxi_wdt_ping,
  	.set_timeout	= sunxi_wdt_set_timeout,

  	.restart	= sunxi_wdt_restart,

  };

  static const struct sunxi_wdt_reg sun4i_wdt_reg = {
  	.wdt_ctrl = 0x00,
  	.wdt_cfg = 0x04,
  	.wdt_mode = 0x04,
  	.wdt_timeout_shift = 3,
  	.wdt_reset_mask = 0x02,
  	.wdt_reset_val = 0x02,
  };

  static const struct sunxi_wdt_reg sun6i_wdt_reg = {
  	.wdt_ctrl = 0x10,
  	.wdt_cfg = 0x14,
  	.wdt_mode = 0x18,
  	.wdt_timeout_shift = 4,
  	.wdt_reset_mask = 0x03,
  	.wdt_reset_val = 0x01,
  };

  static const struct of_device_id sunxi_wdt_dt_ids[] = {
  	{ .compatible = "allwinner,sun4i-a10-wdt", .data = &sun4i_wdt_reg },

  	{ .compatible = "allwinner,sun6i-a31-wdt", .data = &sun6i_wdt_reg },

  	{ /* sentinel */ }
  };
  MODULE_DEVICE_TABLE(of, sunxi_wdt_dt_ids);

  static int sunxi_wdt_probe(struct platform_device *pdev)

  {

  	struct device *dev = &pdev->dev;

  	struct sunxi_wdt_dev *sunxi_wdt;

  	int err;

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

  	if (!sunxi_wdt)
  		return -EINVAL;

  	sunxi_wdt->wdt_regs = of_device_get_match_data(dev);

  	if (!sunxi_wdt->wdt_regs)

  		return -ENODEV;

  	sunxi_wdt->wdt_base = devm_platform_ioremap_resource(pdev, 0);

  	if (IS_ERR(sunxi_wdt->wdt_base))
  		return PTR_ERR(sunxi_wdt->wdt_base);
  
  	sunxi_wdt->wdt_dev.info = &sunxi_wdt_info;
  	sunxi_wdt->wdt_dev.ops = &sunxi_wdt_ops;
  	sunxi_wdt->wdt_dev.timeout = WDT_MAX_TIMEOUT;
  	sunxi_wdt->wdt_dev.max_timeout = WDT_MAX_TIMEOUT;
  	sunxi_wdt->wdt_dev.min_timeout = WDT_MIN_TIMEOUT;

  	sunxi_wdt->wdt_dev.parent = dev;

  	watchdog_init_timeout(&sunxi_wdt->wdt_dev, timeout, dev);

  	watchdog_set_nowayout(&sunxi_wdt->wdt_dev, nowayout);

  	watchdog_set_restart_priority(&sunxi_wdt->wdt_dev, 128);

  
  	watchdog_set_drvdata(&sunxi_wdt->wdt_dev, sunxi_wdt);
  
  	sunxi_wdt_stop(&sunxi_wdt->wdt_dev);

  	watchdog_stop_on_reboot(&sunxi_wdt->wdt_dev);

  	err = devm_watchdog_register_device(dev, &sunxi_wdt->wdt_dev);

  	if (unlikely(err))
  		return err;

  	dev_info(dev, "Watchdog enabled (timeout=%d sec, nowayout=%d)",
  		 sunxi_wdt->wdt_dev.timeout, nowayout);

  
  	return 0;
  }

  static struct platform_driver sunxi_wdt_driver = {
  	.probe		= sunxi_wdt_probe,

  	.driver		= {

  		.name		= DRV_NAME,

  		.of_match_table	= sunxi_wdt_dt_ids,

  	},
  };
  
  module_platform_driver(sunxi_wdt_driver);
  
  module_param(timeout, uint, 0);
  MODULE_PARM_DESC(timeout, "Watchdog heartbeat in seconds");
  
  module_param(nowayout, bool, 0);
  MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
  		"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Carlo Caione <carlo.caione@gmail.com>");
  MODULE_AUTHOR("Henrik Nordstrom <henrik@henriknordstrom.net>");
  MODULE_DESCRIPTION("sunxi WatchDog Timer Driver");
  MODULE_VERSION(DRV_VERSION);