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

  /*
   * Watchdog driver for the A21 VME CPU Boards
   *
   * Copyright (C) 2013 MEN Mikro Elektronik Nuernberg GmbH
   *

   */
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/platform_device.h>
  #include <linux/watchdog.h>
  #include <linux/uaccess.h>

  #include <linux/gpio/consumer.h>

  #include <linux/delay.h>
  #include <linux/bitops.h>

  #include <linux/of.h>

  
  #define NUM_GPIOS 6
  
  enum a21_wdt_gpios {
  	GPIO_WD_ENAB,
  	GPIO_WD_FAST,
  	GPIO_WD_TRIG,
  	GPIO_WD_RST0,
  	GPIO_WD_RST1,
  	GPIO_WD_RST2,
  };
  
  struct a21_wdt_drv {
  	struct watchdog_device wdt;

  	struct gpio_desc *gpios[NUM_GPIOS];

  };
  
  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 a21_wdt_get_bootstatus(struct a21_wdt_drv *drv)
  {
  	int reset = 0;

  	reset |= gpiod_get_value(drv->gpios[GPIO_WD_RST0]) ? (1 << 0) : 0;
  	reset |= gpiod_get_value(drv->gpios[GPIO_WD_RST1]) ? (1 << 1) : 0;
  	reset |= gpiod_get_value(drv->gpios[GPIO_WD_RST2]) ? (1 << 2) : 0;

  
  	return reset;
  }
  
  static int a21_wdt_start(struct watchdog_device *wdt)
  {
  	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);

  	gpiod_set_value(drv->gpios[GPIO_WD_ENAB], 1);

  	return 0;
  }
  
  static int a21_wdt_stop(struct watchdog_device *wdt)
  {
  	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);

  	gpiod_set_value(drv->gpios[GPIO_WD_ENAB], 0);

  	return 0;
  }
  
  static int a21_wdt_ping(struct watchdog_device *wdt)
  {
  	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);

  	gpiod_set_value(drv->gpios[GPIO_WD_TRIG], 0);

  	ndelay(10);

  	gpiod_set_value(drv->gpios[GPIO_WD_TRIG], 1);

  	return 0;
  }
  
  static int a21_wdt_set_timeout(struct watchdog_device *wdt,
  			       unsigned int timeout)
  {
  	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
  
  	if (timeout != 1 && timeout != 30) {

  		dev_err(wdt->parent, "Only 1 and 30 allowed as timeout
  ");

  		return -EINVAL;
  	}
  
  	if (timeout == 30 && wdt->timeout == 1) {

  		dev_err(wdt->parent,

  			"Transition from fast to slow mode not allowed
  ");
  		return -EINVAL;
  	}

  	if (timeout == 1)

  		gpiod_set_value(drv->gpios[GPIO_WD_FAST], 1);

  	else

  		gpiod_set_value(drv->gpios[GPIO_WD_FAST], 0);

  
  	wdt->timeout = timeout;

  	return 0;
  }
  
  static const struct watchdog_info a21_wdt_info = {
  	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
  	.identity = "MEN A21 Watchdog",
  };
  
  static const struct watchdog_ops a21_wdt_ops = {
  	.owner = THIS_MODULE,
  	.start = a21_wdt_start,
  	.stop = a21_wdt_stop,
  	.ping = a21_wdt_ping,
  	.set_timeout = a21_wdt_set_timeout,
  };
  
  static struct watchdog_device a21_wdt = {
  	.info = &a21_wdt_info,
  	.ops = &a21_wdt_ops,
  	.min_timeout = 1,
  	.max_timeout = 30,
  };
  
  static int a21_wdt_probe(struct platform_device *pdev)
  {

  	struct device *dev = &pdev->dev;

  	struct a21_wdt_drv *drv;
  	unsigned int reset = 0;
  	int num_gpios;
  	int ret;
  	int i;

  	drv = devm_kzalloc(dev, sizeof(struct a21_wdt_drv), GFP_KERNEL);

  	if (!drv)
  		return -ENOMEM;

  	num_gpios = gpiod_count(dev, NULL);

  	if (num_gpios != NUM_GPIOS) {

  		dev_err(dev, "gpios DT property wrong, got %d want %d",

  			num_gpios, NUM_GPIOS);
  		return -ENODEV;
  	}

  	/* Request the used GPIOs */
  	for (i = 0; i < num_gpios; i++) {

  		enum gpiod_flags gflags;

  
  		if (i < GPIO_WD_RST0)

  			gflags = GPIOD_ASIS;
  		else
  			gflags = GPIOD_IN;

  		drv->gpios[i] = devm_gpiod_get_index(dev, NULL, i, gflags);
  		if (IS_ERR(drv->gpios[i]))
  			return PTR_ERR(drv->gpios[i]);

  
  		gpiod_set_consumer_name(drv->gpios[i], "MEN A21 Watchdog");
  
  		/*
  		 * Retrieve the initial value from the GPIOs that should be
  		 * output, then set up the line as output with that value.
  		 */
  		if (i < GPIO_WD_RST0) {
  			int val;
  
  			val = gpiod_get_value(drv->gpios[i]);
  			gpiod_direction_output(drv->gpios[i], val);
  		}

  	}

  	watchdog_init_timeout(&a21_wdt, 30, dev);

  	watchdog_set_nowayout(&a21_wdt, nowayout);
  	watchdog_set_drvdata(&a21_wdt, drv);

  	a21_wdt.parent = dev;

  
  	reset = a21_wdt_get_bootstatus(drv);
  	if (reset == 2)
  		a21_wdt.bootstatus |= WDIOF_EXTERN1;
  	else if (reset == 4)
  		a21_wdt.bootstatus |= WDIOF_CARDRESET;
  	else if (reset == 5)
  		a21_wdt.bootstatus |= WDIOF_POWERUNDER;
  	else if (reset == 7)
  		a21_wdt.bootstatus |= WDIOF_EXTERN2;

  	drv->wdt = a21_wdt;

  	dev_set_drvdata(dev, drv);

  	ret = devm_watchdog_register_device(dev, &a21_wdt);

  	if (ret)

  		return ret;

  	dev_info(dev, "MEN A21 watchdog timer driver enabled
  ");

  
  	return 0;

  }
  
  static void a21_wdt_shutdown(struct platform_device *pdev)
  {
  	struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);

  	gpiod_set_value(drv->gpios[GPIO_WD_ENAB], 0);

  }
  
  static const struct of_device_id a21_wdt_ids[] = {
  	{ .compatible = "men,a021-wdt" },
  	{ },
  };

  MODULE_DEVICE_TABLE(of, a21_wdt_ids);

  
  static struct platform_driver a21_wdt_driver = {
  	.probe = a21_wdt_probe,

  	.shutdown = a21_wdt_shutdown,
  	.driver = {
  		.name = "a21-watchdog",
  		.of_match_table = a21_wdt_ids,
  	},
  };
  
  module_platform_driver(a21_wdt_driver);
  
  MODULE_AUTHOR("MEN Mikro Elektronik");
  MODULE_DESCRIPTION("MEN A21 Watchdog");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("platform:a21-watchdog");