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* Copyright (C) 2015 The Android Open Source Project
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#include <hardware/hardware.h>
* The id of this module
* The Boot Control HAL is designed to allow for managing sets of redundant
* partitions, called slots, that can be booted from independantly. Slots
* are sets of partitions whose names differ only by a given suffix.
* They are identified here by a 0 indexed number, and associated with their
* suffix, which can be appended to the base name for any particular partition
* to find the one associated with that slot. The bootloader must pass the suffix
* of the currently active slot either through a kernel command line property at
* androidboot.slot_suffix, or the device tree at /firmware/android/slot_suffix.
* The primary use of this set up is to allow for background updates while the
* device is running, and to provide a fallback in the event that the update fails.
* Every hardware module must have a data structure named HAL_MODULE_INFO_SYM
* and the fields of this data structure must begin with hw_module_t
* followed by module specific information.
typedef struct boot_control_module {
struct hw_module_t common;
* (*init)() perform any initialization tasks needed for the HAL.
* This is called only once.
void (*init)(struct boot_control_module *module);
* (*getNumberSlots)() returns the number of available slots.
* For instance, a system with a single set of partitions would return
* 1, a system with A/B would return 2, A/B/C -> 3...
unsigned (*getNumberSlots)(struct boot_control_module *module);
* (*getCurrentSlot)() returns the value letting the system know
* whether the current slot is A or B. The meaning of A and B is
* left up to the implementer. It is assumed that if the current slot
* is A, then the block devices underlying B can be accessed directly
* without any risk of corruption.
* The returned value is always guaranteed to be strictly less than the
* value returned by getNumberSlots. Slots start at 0 and
* finish at getNumberSlots() - 1
unsigned (*getCurrentSlot)(struct boot_control_module *module);
* (*markBootSuccessful)() marks the current slot
* as having booted successfully
* Returns 0 on success, -errno on error.
int (*markBootSuccessful)(struct boot_control_module *module);
* (*setActiveBootSlot)() marks the slot passed in parameter as
* the active boot slot (see getCurrentSlot for an explanation
* of the "slot" parameter). This overrides any previous call to
* setSlotAsUnbootable.
* Returns 0 on success, -errno on error.
int (*setActiveBootSlot)(struct boot_control_module *module, unsigned slot);
* (*setSlotAsUnbootable)() marks the slot passed in parameter as
* an unbootable. This can be used while updating the contents of the slot's
* partitions, so that the system will not attempt to boot a known bad set up.
* Returns 0 on success, -errno on error.
int (*setSlotAsUnbootable)(struct boot_control_module *module, unsigned slot);
* (*isSlotBootable)() returns if the slot passed in parameter is
* bootable. Note that slots can be made unbootable by both the
* bootloader and by the OS using setSlotAsUnbootable.
* Returns 1 if the slot is bootable, 0 if it's not, and -errno on
* error.
int (*isSlotBootable)(struct boot_control_module *module, unsigned slot);
* (*getSuffix)() returns the string suffix used by partitions that
* correspond to the slot number passed in parameter. The returned string
* is expected to be statically allocated and not need to be freed.
* Returns NULL if slot does not match an existing slot.
const char* (*getSuffix)(struct boot_control_module *module, unsigned slot);
* (*isSlotMarkedSucessful)() returns if the slot passed in parameter has
* been marked as successful using markBootSuccessful.
* Returns 1 if the slot has been marked as successful, 0 if it's
* not the case, and -errno on error.
int (*isSlotMarkedSuccessful)(struct boot_control_module *module, unsigned slot);
* Returns the active slot to boot into on the next boot. If
* setActiveBootSlot() has been called, the getter function should return
* the same slot as the one provided in the last setActiveBootSlot() call.
unsigned (*getActiveBootSlot)(struct boot_control_module *module);
void* reserved[30];
} boot_control_module_t;