LXR uboot/include/wdt.h

   1/* SPDX-License-Identifier: GPL-2.0+ */
   2/*
   3 * Copyright 2017 Google, Inc
   4 */
   5
   6#ifndef _WDT_H_
   7#define _WDT_H_
   8
   9struct udevice;
  10
  11/*
  12 * Implement a simple watchdog uclass. Watchdog is basically a timer that
  13 * is used to detect or recover from malfunction. During normal operation
  14 * the watchdog would be regularly reset to prevent it from timing out.
  15 * If, due to a hardware fault or program error, the computer fails to reset
  16 * the watchdog, the timer will elapse and generate a timeout signal.
  17 * The timeout signal is used to initiate corrective action or actions,
  18 * which typically include placing the system in a safe, known state.
  19 */
  20
  21/*
  22 * Start the timer
  23 *
  24 * @dev: WDT Device
  25 * @timeout_ms: Number of ticks (milliseconds) before timer expires
  26 * @flags: Driver specific flags. This might be used to specify
  27 * which action needs to be executed when the timer expires
  28 * @return: 0 if OK, -ve on error
  29 */
  30int wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags);
  31
  32/*
  33 * Stop the timer, thus disabling the Watchdog. Use wdt_start to start it again.
  34 *
  35 * @dev: WDT Device
  36 * @return: 0 if OK, -ve on error
  37 */
  38int wdt_stop(struct udevice *dev);
  39
  40/*
  41 * Reset the timer, typically restoring the counter to
  42 * the value configured by start()
  43 *
  44 * @dev: WDT Device
  45 * @return: 0 if OK, -ve on error
  46 */
  47int wdt_reset(struct udevice *dev);
  48
  49/*
  50 * Expire the timer, thus executing its action immediately.
  51 * This is typically used to reset the board or peripherals.
  52 *
  53 * @dev: WDT Device
  54 * @flags: Driver specific flags
  55 * @return 0 if OK -ve on error. If wdt action is system reset,
  56 * this function may never return.
  57 */
  58int wdt_expire_now(struct udevice *dev, ulong flags);
  59
  60/*
  61 * struct wdt_ops - Driver model wdt operations
  62 *
  63 * The uclass interface is implemented by all wdt devices which use
  64 * driver model.
  65 */
  66struct wdt_ops {
  67        /*
  68         * Start the timer
  69         *
  70         * @dev: WDT Device
  71         * @timeout_ms: Number of ticks (milliseconds) before the timer expires
  72         * @flags: Driver specific flags. This might be used to specify
  73         * which action needs to be executed when the timer expires
  74         * @return: 0 if OK, -ve on error
  75         */
  76        int (*start)(struct udevice *dev, u64 timeout_ms, ulong flags);
  77        /*
  78         * Stop the timer
  79         *
  80         * @dev: WDT Device
  81         * @return: 0 if OK, -ve on error
  82         */
  83        int (*stop)(struct udevice *dev);
  84        /*
  85         * Reset the timer, typically restoring the counter to
  86         * the value configured by start()
  87         *
  88         * @dev: WDT Device
  89         * @return: 0 if OK, -ve on error
  90         */
  91        int (*reset)(struct udevice *dev);
  92        /*
  93         * Expire the timer, thus executing the action immediately (optional)
  94         *
  95         * If this function is not provided, a default implementation
  96         * will be used, which sets the counter to 1
  97         * and waits forever. This is good enough for system level
  98         * reset, where the function is not expected to return, but might not be
  99         * good enough for other use cases.
 100         *
 101         * @dev: WDT Device
 102         * @flags: Driver specific flags
 103         * @return 0 if OK -ve on error. May not return.
 104         */
 105        int (*expire_now)(struct udevice *dev, ulong flags);
 106};
 107
 108int initr_watchdog(void);
 109
 110#endif  /* _WDT_H_ */
 111