text: // SPDX-License-Identifier: GPL-2.0-or-later
  /*
   * Copyright (C) Nokia Corporation
   *
   * Written by Timo Kokkonen <timo.t.kokkonen at nokia.com>
   */
  
  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/slab.h>
  #include <linux/kernel.h>
  #include <linux/watchdog.h>
  #include <linux/platform_device.h>
  #include <linux/mfd/twl.h>
  
  #define TWL4030_WATCHDOG_CFG_REG_OFFS	0x3
  
  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 int twl4030_wdt_write(unsigned char val)
  {
  	return twl_i2c_write_u8(TWL_MODULE_PM_RECEIVER, val,
  					TWL4030_WATCHDOG_CFG_REG_OFFS);
  }
  
  static int twl4030_wdt_start(struct watchdog_device *wdt)
  {
  	return twl4030_wdt_write(wdt->timeout + 1);
  }
  
  static int twl4030_wdt_stop(struct watchdog_device *wdt)
  {
  	return twl4030_wdt_write(0);
  }
  
  static int twl4030_wdt_set_timeout(struct watchdog_device *wdt,
  				   unsigned int timeout)
  {
  	wdt->timeout = timeout;
  	return 0;
  }
  
  static const struct watchdog_info twl4030_wdt_info = {
  	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
  	.identity = "TWL4030 Watchdog",
  };
  
  static const struct watchdog_ops twl4030_wdt_ops = {
  	.owner		= THIS_MODULE,
  	.start		= twl4030_wdt_start,
  	.stop		= twl4030_wdt_stop,
  	.set_timeout	= twl4030_wdt_set_timeout,
  };
  
  static int twl4030_wdt_probe(struct platform_device *pdev)
  {
  	struct device *dev = &pdev->dev;
  	struct watchdog_device *wdt;
  
  	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
  	if (!wdt)
  		return -ENOMEM;
  
  	wdt->info		= &twl4030_wdt_info;
  	wdt->ops		= &twl4030_wdt_ops;
  	wdt->status		= 0;
  	wdt->timeout		= 30;
  	wdt->min_timeout	= 1;
  	wdt->max_timeout	= 30;
  	wdt->parent = dev;
  
  	watchdog_set_nowayout(wdt, nowayout);
  	platform_set_drvdata(pdev, wdt);
  
  	twl4030_wdt_stop(wdt);
  
  	return devm_watchdog_register_device(dev, wdt);
  }
  
  #ifdef CONFIG_PM
  static int twl4030_wdt_suspend(struct platform_device *pdev, pm_message_t state)
  {
  	struct watchdog_device *wdt = platform_get_drvdata(pdev);
  	if (watchdog_active(wdt))
  		return twl4030_wdt_stop(wdt);
  
  	return 0;
  }
  
  static int twl4030_wdt_resume(struct platform_device *pdev)
  {
  	struct watchdog_device *wdt = platform_get_drvdata(pdev);
  	if (watchdog_active(wdt))
  		return twl4030_wdt_start(wdt);
  
  	return 0;
  }
  #else
  #define twl4030_wdt_suspend        NULL
  #define twl4030_wdt_resume         NULL
  #endif
  
  static const struct of_device_id twl_wdt_of_match[] = {
  	{ .compatible = "ti,twl4030-wdt", },
  	{ },
  };
  MODULE_DEVICE_TABLE(of, twl_wdt_of_match);
  
  static struct platform_driver twl4030_wdt_driver = {
  	.probe		= twl4030_wdt_probe,
  	.suspend	= twl4030_wdt_suspend,
  	.resume		= twl4030_wdt_resume,
  	.driver		= {
  		.name		= "twl4030_wdt",
  		.of_match_table	= twl_wdt_of_match,
  	},
  };
  
  module_platform_driver(twl4030_wdt_driver);
  
  MODULE_AUTHOR("Nokia Corporation");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("platform:twl4030_wdt");
  
  