/*
   * Copyright 2017 Google, Inc
   *
   * SPDX-License-Identifier:	GPL-2.0+
   */
  
  #ifndef _WDT_H_
  #define _WDT_H_
  
  /*
   * Implement a simple watchdog uclass. Watchdog is basically a timer that
   * is used to detect or recover from malfunction. During normal operation
   * the watchdog would be regularly reset to prevent it from timing out.
   * If, due to a hardware fault or program error, the computer fails to reset
   * the watchdog, the timer will elapse and generate a timeout signal.
   * The timeout signal is used to initiate corrective action or actions,
   * which typically include placing the system in a safe, known state.
   */
  
  /*
   * Start the timer
   *
   * @dev: WDT Device

   * @timeout_ms: Number of ticks (milliseconds) before timer expires

   * @flags: Driver specific flags. This might be used to specify
   * which action needs to be executed when the timer expires
   * @return: 0 if OK, -ve on error
   */

  int wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags);

  
  /*
   * Stop the timer, thus disabling the Watchdog. Use wdt_start to start it again.
   *
   * @dev: WDT Device
   * @return: 0 if OK, -ve on error
   */
  int wdt_stop(struct udevice *dev);
  
  /*
   * Reset the timer, typically restoring the counter to
   * the value configured by start()
   *
   * @dev: WDT Device
   * @return: 0 if OK, -ve on error
   */
  int wdt_reset(struct udevice *dev);
  
  /*
   * Expire the timer, thus executing its action immediately.
   * This is typically used to reset the board or peripherals.
   *
   * @dev: WDT Device
   * @flags: Driver specific flags
   * @return 0 if OK -ve on error. If wdt action is system reset,
   * this function may never return.
   */
  int wdt_expire_now(struct udevice *dev, ulong flags);
  
  /*
   * struct wdt_ops - Driver model wdt operations
   *
   * The uclass interface is implemented by all wdt devices which use
   * driver model.
   */
  struct wdt_ops {
  	/*
  	 * Start the timer
  	 *
  	 * @dev: WDT Device

  	 * @timeout_ms: Number of ticks (milliseconds) before the timer expires

  	 * @flags: Driver specific flags. This might be used to specify
  	 * which action needs to be executed when the timer expires
  	 * @return: 0 if OK, -ve on error
  	 */

  	int (*start)(struct udevice *dev, u64 timeout_ms, ulong flags);

  	/*
  	 * Stop the timer
  	 *
  	 * @dev: WDT Device
  	 * @return: 0 if OK, -ve on error
  	 */
  	int (*stop)(struct udevice *dev);
  	/*
  	 * Reset the timer, typically restoring the counter to
  	 * the value configured by start()
  	 *
  	 * @dev: WDT Device
  	 * @return: 0 if OK, -ve on error
  	 */
  	int (*reset)(struct udevice *dev);
  	/*
  	 * Expire the timer, thus executing the action immediately (optional)
  	 *
  	 * If this function is not provided, a default implementation
  	 * will be used, which sets the counter to 1
  	 * and waits forever. This is good enough for system level
  	 * reset, where the function is not expected to return, but might not be
  	 * good enough for other use cases.
  	 *
  	 * @dev: WDT Device
  	 * @flags: Driver specific flags
  	 * @return 0 if OK -ve on error. May not return.
  	 */
  	int (*expire_now)(struct udevice *dev, ulong flags);
  };
  
  #endif  /* _WDT_H_ */