/*
   * Watchdog driver for the A21 VME CPU Boards
   *
   * Copyright (C) 2013 MEN Mikro Elektronik Nuernberg GmbH
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation
   */
  #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.h>
  #include <linux/of_gpio.h>
  #include <linux/delay.h>
  #include <linux/bitops.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 mutex lock;
  	unsigned 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 |= gpio_get_value(drv->gpios[GPIO_WD_RST0]) ? (1 << 0) : 0;
  	reset |= gpio_get_value(drv->gpios[GPIO_WD_RST1]) ? (1 << 1) : 0;
  	reset |= gpio_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);
  
  	mutex_lock(&drv->lock);
  
  	gpio_set_value(drv->gpios[GPIO_WD_ENAB], 1);
  
  	mutex_unlock(&drv->lock);
  
  	return 0;
  }
  
  static int a21_wdt_stop(struct watchdog_device *wdt)
  {
  	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
  
  	mutex_lock(&drv->lock);
  
  	gpio_set_value(drv->gpios[GPIO_WD_ENAB], 0);
  
  	mutex_unlock(&drv->lock);
  
  	return 0;
  }
  
  static int a21_wdt_ping(struct watchdog_device *wdt)
  {
  	struct a21_wdt_drv *drv = watchdog_get_drvdata(wdt);
  
  	mutex_lock(&drv->lock);
  
  	gpio_set_value(drv->gpios[GPIO_WD_TRIG], 0);
  	ndelay(10);
  	gpio_set_value(drv->gpios[GPIO_WD_TRIG], 1);
  
  	mutex_unlock(&drv->lock);
  
  	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->dev, "Only 1 and 30 allowed as timeout
  ");
  		return -EINVAL;
  	}
  
  	if (timeout == 30 && wdt->timeout == 1) {
  		dev_err(wdt->dev,
  			"Transition from fast to slow mode not allowed
  ");
  		return -EINVAL;
  	}
  
  	mutex_lock(&drv->lock);
  
  	if (timeout == 1)
  		gpio_set_value(drv->gpios[GPIO_WD_FAST], 1);
  	else
  		gpio_set_value(drv->gpios[GPIO_WD_FAST], 0);
  
  	wdt->timeout = timeout;
  
  	mutex_unlock(&drv->lock);
  
  	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_node *node;
  	struct a21_wdt_drv *drv;
  	unsigned int reset = 0;
  	int num_gpios;
  	int ret;
  	int i;
  
  	drv = devm_kzalloc(&pdev->dev, sizeof(struct a21_wdt_drv), GFP_KERNEL);
  	if (!drv)
  		return -ENOMEM;
  
  	/* Fill GPIO pin array */
  	node = pdev->dev.of_node;
  
  	num_gpios = of_gpio_count(node);
  	if (num_gpios != NUM_GPIOS) {
  		dev_err(&pdev->dev, "gpios DT property wrong, got %d want %d",
  			num_gpios, NUM_GPIOS);
  		return -ENODEV;
  	}
  
  	for (i = 0; i < num_gpios; i++) {
  		int val;
  
  		val = of_get_gpio(node, i);
  		if (val < 0)
  			return val;
  
  		drv->gpios[i] = val;
  	}
  
  	/* Request the used GPIOs */
  	for (i = 0; i < num_gpios; i++) {
  		ret = devm_gpio_request(&pdev->dev, drv->gpios[i],
  					"MEN A21 Watchdog");
  		if (ret)
  			return ret;
  
  		if (i < GPIO_WD_RST0)
  			ret = gpio_direction_output(drv->gpios[i],
  						gpio_get_value(drv->gpios[i]));
  		else		/* GPIO_WD_RST[0..2] are inputs */
  			ret = gpio_direction_input(drv->gpios[i]);
  		if (ret)
  			return ret;
  	}
  
  	mutex_init(&drv->lock);
  	watchdog_init_timeout(&a21_wdt, 30, &pdev->dev);
  	watchdog_set_nowayout(&a21_wdt, nowayout);
  	watchdog_set_drvdata(&a21_wdt, drv);
  
  	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;
  
  	ret = watchdog_register_device(&a21_wdt);
  	if (ret) {
  		dev_err(&pdev->dev, "Cannot register watchdog device
  ");
  		goto err_register_wd;
  	}
  
  	dev_set_drvdata(&pdev->dev, drv);
  
  	dev_info(&pdev->dev, "MEN A21 watchdog timer driver enabled
  ");
  
  	return 0;
  
  err_register_wd:
  	mutex_destroy(&drv->lock);
  
  	return ret;
  }
  
  static int a21_wdt_remove(struct platform_device *pdev)
  {
  	struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);
  
  	dev_warn(&pdev->dev,
  		"Unregistering A21 watchdog driver, board may reboot
  ");
  
  	watchdog_unregister_device(&drv->wdt);
  
  	mutex_destroy(&drv->lock);
  
  	return 0;
  }
  
  static void a21_wdt_shutdown(struct platform_device *pdev)
  {
  	struct a21_wdt_drv *drv = dev_get_drvdata(&pdev->dev);
  
  	gpio_set_value(drv->gpios[GPIO_WD_ENAB], 0);
  }
  
  static const struct of_device_id a21_wdt_ids[] = {
  	{ .compatible = "men,a021-wdt" },
  	{ },
  };
  
  static struct platform_driver a21_wdt_driver = {
  	.probe = a21_wdt_probe,
  	.remove = a21_wdt_remove,
  	.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");