22cdb3f0f1
It is is sometimes desired to be able to skip decrementing the number of tries remaining in an Android A/B boot, and instead just check which slot will be tried later. This can commonly be be the case for platforms that want to A/B u-boot itself, but are required to boot from a FAT MBR partition. In these cases, u-boot must do an early check that the MBR points to the correct A/B boot partition, and if not rewrite the MBR to point to the correct one and reboot. Decrementing the try count in this case is not desired because it means that each u-boot might constantly ping-pong overwriting the MBR and rebooting until all the retries are used up. Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
37 lines
1.2 KiB
C
37 lines
1.2 KiB
C
/* SPDX-License-Identifier: BSD-2-Clause */
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/*
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* Copyright (C) 2017 The Android Open Source Project
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*/
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#ifndef __ANDROID_AB_H
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#define __ANDROID_AB_H
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struct blk_desc;
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struct disk_partition;
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/* Android standard boot slot names are 'a', 'b', 'c', ... */
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#define BOOT_SLOT_NAME(slot_num) ('a' + (slot_num))
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/* Number of slots */
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#define NUM_SLOTS 2
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/**
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* Select the slot where to boot from.
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*
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* On Android devices with more than one boot slot (multiple copies of the
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* kernel and system images) selects which slot should be used to boot from and
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* registers the boot attempt. This is used in by the new A/B update model where
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* one slot is updated in the background while running from the other slot. If
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* the selected slot did not successfully boot in the past, a boot attempt is
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* registered before returning from this function so it isn't selected
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* indefinitely.
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*
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* @param[in] dev_desc Place to store the device description pointer
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* @param[in] part_info Place to store the partition information
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* Return: The slot number (>= 0) on success, or a negative on error
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*/
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int ab_select_slot(struct blk_desc *dev_desc, struct disk_partition *part_info,
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bool dec_tries);
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#endif /* __ANDROID_AB_H */
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