| maxims@google.com | 0753bc2 | 2017-04-17 12:00:21 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright 2017 Google, Inc |
| 3 | * |
| 4 | * SPDX-License-Identifier: GPL-2.0+ |
| 5 | */ |
| 6 | |
| 7 | #ifndef _WDT_H_ |
| 8 | #define _WDT_H_ |
| 9 | |
| 10 | /* |
| 11 | * Implement a simple watchdog uclass. Watchdog is basically a timer that |
| 12 | * is used to detect or recover from malfunction. During normal operation |
| 13 | * the watchdog would be regularly reset to prevent it from timing out. |
| 14 | * If, due to a hardware fault or program error, the computer fails to reset |
| 15 | * the watchdog, the timer will elapse and generate a timeout signal. |
| 16 | * The timeout signal is used to initiate corrective action or actions, |
| 17 | * which typically include placing the system in a safe, known state. |
| 18 | */ |
| 19 | |
| 20 | /* |
| 21 | * Start the timer |
| 22 | * |
| 23 | * @dev: WDT Device |
| 24 | * @timeout: Number of ticks before timer expires |
| 25 | * @flags: Driver specific flags. This might be used to specify |
| 26 | * which action needs to be executed when the timer expires |
| 27 | * @return: 0 if OK, -ve on error |
| 28 | */ |
| 29 | int wdt_start(struct udevice *dev, u64 timeout, ulong flags); |
| 30 | |
| 31 | /* |
| 32 | * Stop the timer, thus disabling the Watchdog. Use wdt_start to start it again. |
| 33 | * |
| 34 | * @dev: WDT Device |
| 35 | * @return: 0 if OK, -ve on error |
| 36 | */ |
| 37 | int wdt_stop(struct udevice *dev); |
| 38 | |
| 39 | /* |
| 40 | * Reset the timer, typically restoring the counter to |
| 41 | * the value configured by start() |
| 42 | * |
| 43 | * @dev: WDT Device |
| 44 | * @return: 0 if OK, -ve on error |
| 45 | */ |
| 46 | int wdt_reset(struct udevice *dev); |
| 47 | |
| 48 | /* |
| 49 | * Expire the timer, thus executing its action immediately. |
| 50 | * This is typically used to reset the board or peripherals. |
| 51 | * |
| 52 | * @dev: WDT Device |
| 53 | * @flags: Driver specific flags |
| 54 | * @return 0 if OK -ve on error. If wdt action is system reset, |
| 55 | * this function may never return. |
| 56 | */ |
| 57 | int wdt_expire_now(struct udevice *dev, ulong flags); |
| 58 | |
| 59 | /* |
| 60 | * struct wdt_ops - Driver model wdt operations |
| 61 | * |
| 62 | * The uclass interface is implemented by all wdt devices which use |
| 63 | * driver model. |
| 64 | */ |
| 65 | struct wdt_ops { |
| 66 | /* |
| 67 | * Start the timer |
| 68 | * |
| 69 | * @dev: WDT Device |
| 70 | * @timeout: Number of ticks before the timer expires |
| 71 | * @flags: Driver specific flags. This might be used to specify |
| 72 | * which action needs to be executed when the timer expires |
| 73 | * @return: 0 if OK, -ve on error |
| 74 | */ |
| 75 | int (*start)(struct udevice *dev, u64 timeout, ulong flags); |
| 76 | /* |
| 77 | * Stop the timer |
| 78 | * |
| 79 | * @dev: WDT Device |
| 80 | * @return: 0 if OK, -ve on error |
| 81 | */ |
| 82 | int (*stop)(struct udevice *dev); |
| 83 | /* |
| 84 | * Reset the timer, typically restoring the counter to |
| 85 | * the value configured by start() |
| 86 | * |
| 87 | * @dev: WDT Device |
| 88 | * @return: 0 if OK, -ve on error |
| 89 | */ |
| 90 | int (*reset)(struct udevice *dev); |
| 91 | /* |
| 92 | * Expire the timer, thus executing the action immediately (optional) |
| 93 | * |
| 94 | * If this function is not provided, a default implementation |
| 95 | * will be used, which sets the counter to 1 |
| 96 | * and waits forever. This is good enough for system level |
| 97 | * reset, where the function is not expected to return, but might not be |
| 98 | * good enough for other use cases. |
| 99 | * |
| 100 | * @dev: WDT Device |
| 101 | * @flags: Driver specific flags |
| 102 | * @return 0 if OK -ve on error. May not return. |
| 103 | */ |
| 104 | int (*expire_now)(struct udevice *dev, ulong flags); |
| 105 | }; |
| 106 | |
| 107 | #endif /* _WDT_H_ */ |