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- /* SPDX-License-Identifier: GPL-2.0+ */
- /*
- * Copyright 2017 Google, Inc
- */
- #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_ */
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