text: /*
   * Watchdog driver for Ricoh RN5T618 PMIC
   *
   * Copyright (C) 2014 Beniamino Galvani <b.galvani@gmail.com>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * version 2 as published by the Free Software Foundation.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program. If not, see <http://www.gnu.org/licenses/>.
   */
  
  #include <linux/device.h>
  #include <linux/mfd/rn5t618.h>
  #include <linux/module.h>
  #include <linux/platform_device.h>
  #include <linux/watchdog.h>
  
  #define DRIVER_NAME "rn5t618-wdt"
  
  static bool nowayout = WATCHDOG_NOWAYOUT;
  static unsigned int timeout;
  
  module_param(timeout, uint, 0);
  MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds");
  
  module_param(nowayout, bool, 0);
  MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
  		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  
  struct rn5t618_wdt {
  	struct watchdog_device wdt_dev;
  	struct rn5t618 *rn5t618;
  };
  
  /*
   * This array encodes the values of WDOGTIM field for the supported
   * watchdog expiration times. If the watchdog is not accessed before
   * the timer expiration, the PMU generates an interrupt and if the CPU
   * doesn't clear it within one second the system is restarted.
   */
  static const struct {
  	u8 reg_val;
  	unsigned int time;
  } rn5t618_wdt_map[] = {
  	{ 0, 1 },
  	{ 1, 8 },
  	{ 2, 32 },
  	{ 3, 128 },
  };
  
  static int rn5t618_wdt_set_timeout(struct watchdog_device *wdt_dev,
  				   unsigned int t)
  {
  	struct rn5t618_wdt *wdt = watchdog_get_drvdata(wdt_dev);
  	int ret, i;
  
  	for (i = 0; i < ARRAY_SIZE(rn5t618_wdt_map); i++) {
  		if (rn5t618_wdt_map[i].time + 1 >= t)
  			break;
  	}
  
  	if (i == ARRAY_SIZE(rn5t618_wdt_map))
  		return -EINVAL;
  
  	ret = regmap_update_bits(wdt->rn5t618->regmap, RN5T618_WATCHDOG,
  				 RN5T618_WATCHDOG_WDOGTIM_M,
  				 rn5t618_wdt_map[i].reg_val);
  	if (!ret)
  		wdt_dev->timeout = rn5t618_wdt_map[i].time;
  
  	return ret;
  }
  
  static int rn5t618_wdt_start(struct watchdog_device *wdt_dev)
  {
  	struct rn5t618_wdt *wdt = watchdog_get_drvdata(wdt_dev);
  	int ret;
  
  	ret = rn5t618_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
  	if (ret)
  		return ret;
  
  	/* enable repower-on */
  	ret = regmap_update_bits(wdt->rn5t618->regmap, RN5T618_REPCNT,
  				 RN5T618_REPCNT_REPWRON,
  				 RN5T618_REPCNT_REPWRON);
  	if (ret)
  		return ret;
  
  	/* enable watchdog */
  	ret = regmap_update_bits(wdt->rn5t618->regmap, RN5T618_WATCHDOG,
  				 RN5T618_WATCHDOG_WDOGEN,
  				 RN5T618_WATCHDOG_WDOGEN);
  	if (ret)
  		return ret;
  
  	/* enable watchdog interrupt */
  	return regmap_update_bits(wdt->rn5t618->regmap, RN5T618_PWRIREN,
  				  RN5T618_PWRIRQ_IR_WDOG,
  				  RN5T618_PWRIRQ_IR_WDOG);
  }
  
  static int rn5t618_wdt_stop(struct watchdog_device *wdt_dev)
  {
  	struct rn5t618_wdt *wdt = watchdog_get_drvdata(wdt_dev);
  
  	return regmap_update_bits(wdt->rn5t618->regmap, RN5T618_WATCHDOG,
  				  RN5T618_WATCHDOG_WDOGEN, 0);
  }
  
  static int rn5t618_wdt_ping(struct watchdog_device *wdt_dev)
  {
  	struct rn5t618_wdt *wdt = watchdog_get_drvdata(wdt_dev);
  	unsigned int val;
  	int ret;
  
  	/* The counter is restarted after a R/W access to watchdog register */
  	ret = regmap_read(wdt->rn5t618->regmap, RN5T618_WATCHDOG, &val);
  	if (ret)
  		return ret;
  
  	ret = regmap_write(wdt->rn5t618->regmap, RN5T618_WATCHDOG, val);
  	if (ret)
  		return ret;
  
  	/* Clear pending watchdog interrupt */
  	return regmap_update_bits(wdt->rn5t618->regmap, RN5T618_PWRIRQ,
  				  RN5T618_PWRIRQ_IR_WDOG, 0);
  }
  
  static struct watchdog_info rn5t618_wdt_info = {
  	.options	= WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
  			  WDIOF_KEEPALIVEPING,
  	.identity	= DRIVER_NAME,
  };
  
  static struct watchdog_ops rn5t618_wdt_ops = {
  	.owner          = THIS_MODULE,
  	.start          = rn5t618_wdt_start,
  	.stop           = rn5t618_wdt_stop,
  	.ping           = rn5t618_wdt_ping,
  	.set_timeout    = rn5t618_wdt_set_timeout,
  };
  
  static int rn5t618_wdt_probe(struct platform_device *pdev)
  {
  	struct rn5t618 *rn5t618 = dev_get_drvdata(pdev->dev.parent);
  	struct rn5t618_wdt *wdt;
  	int min_timeout, max_timeout;
  
  	wdt = devm_kzalloc(&pdev->dev, sizeof(struct rn5t618_wdt), GFP_KERNEL);
  	if (!wdt)
  		return -ENOMEM;
  
  	min_timeout = rn5t618_wdt_map[0].time;
  	max_timeout = rn5t618_wdt_map[ARRAY_SIZE(rn5t618_wdt_map) - 1].time;
  
  	wdt->rn5t618 = rn5t618;
  	wdt->wdt_dev.info = &rn5t618_wdt_info;
  	wdt->wdt_dev.ops = &rn5t618_wdt_ops;
  	wdt->wdt_dev.min_timeout = min_timeout;
  	wdt->wdt_dev.max_timeout = max_timeout;
  	wdt->wdt_dev.timeout = max_timeout;
  	wdt->wdt_dev.parent = &pdev->dev;
  
  	watchdog_set_drvdata(&wdt->wdt_dev, wdt);
  	watchdog_init_timeout(&wdt->wdt_dev, timeout, &pdev->dev);
  	watchdog_set_nowayout(&wdt->wdt_dev, nowayout);
  
  	platform_set_drvdata(pdev, wdt);
  
  	return watchdog_register_device(&wdt->wdt_dev);
  }
  
  static int rn5t618_wdt_remove(struct platform_device *pdev)
  {
  	struct rn5t618_wdt *wdt = platform_get_drvdata(pdev);
  
  	watchdog_unregister_device(&wdt->wdt_dev);
  
  	return 0;
  }
  
  static struct platform_driver rn5t618_wdt_driver = {
  	.probe = rn5t618_wdt_probe,
  	.remove = rn5t618_wdt_remove,
  	.driver = {
  		.name	= DRIVER_NAME,
  	},
  };
  
  module_platform_driver(rn5t618_wdt_driver);
  
  MODULE_AUTHOR("Beniamino Galvani <b.galvani@gmail.com>");
  MODULE_DESCRIPTION("RN5T618 watchdog driver");
  MODULE_LICENSE("GPL v2");
  