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 * Stop all registered watchdog devices. 42 * 43 * @return: 0 if ok, first error encountered otherwise (but wdt_stop() 44 * is still called on following devices) 45 */ 46int wdt_stop_all(void); 47 48/* 49 * Reset the timer, typically restoring the counter to 50 * the value configured by start() 51 * 52 * @dev: WDT Device 53 * @return: 0 if OK, -ve on error 54 */ 55int wdt_reset(struct udevice *dev); 56 57/* 58 * Expire the timer, thus executing its action immediately. 59 * This is typically used to reset the board or peripherals. 60 * 61 * @dev: WDT Device 62 * @flags: Driver specific flags 63 * Return: 0 if OK -ve on error. If wdt action is system reset, 64 * this function may never return. 65 */ 66int wdt_expire_now(struct udevice *dev, ulong flags); 67 68/* 69 * struct wdt_ops - Driver model wdt operations 70 * 71 * The uclass interface is implemented by all wdt devices which use 72 * driver model. 73 */ 74struct wdt_ops { 75 /* 76 * Start the timer 77 * 78 * @dev: WDT Device 79 * @timeout_ms: Number of ticks (milliseconds) before the timer expires 80 * @flags: Driver specific flags. This might be used to specify 81 * which action needs to be executed when the timer expires 82 * @return: 0 if OK, -ve on error 83 */ 84 int (*start)(struct udevice *dev, u64 timeout_ms, ulong flags); 85 /* 86 * Stop the timer 87 * 88 * @dev: WDT Device 89 * @return: 0 if OK, -ve on error 90 */ 91 int (*stop)(struct udevice *dev); 92 /* 93 * Reset the timer, typically restoring the counter to 94 * the value configured by start() 95 * 96 * @dev: WDT Device 97 * @return: 0 if OK, -ve on error 98 */ 99 int (*reset)(struct udevice *dev); 100 /* 101 * Expire the timer, thus executing the action immediately (optional) 102 * 103 * If this function is not provided, a default implementation 104 * will be used, which sets the counter to 1 105 * and waits forever. This is good enough for system level 106 * reset, where the function is not expected to return, but might not be 107 * good enough for other use cases. 108 * 109 * @dev: WDT Device 110 * @flags: Driver specific flags 111 * @return 0 if OK -ve on error. May not return. 112 */ 113 int (*expire_now)(struct udevice *dev, ulong flags); 114}; 115 116int initr_watchdog(void); 117 118#endif /* _WDT_H_ */ 119