linux/Documentation/arm/Samsung/Bootloader-interface.txt

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Interface between kernel and boot loaders on Exynos boards
==========================================================
Author: Krzysztof Kozlowski
Date : 6 June 2015
The document tries to describe currently used interface between Linux kernel
and boot loaders on Samsung Exynos based boards. This is not a definition
of interface but rather a description of existing state, a reference
for information purpose only.
In the document "boot loader" means any of following: U-boot, proprietary
SBOOT or any other firmware for ARMv7 and ARMv8 initializing the board before
executing kernel.
1. Non-Secure mode
Address: sysram_ns_base_addr
Offset Value Purpose
=============================================================================
0x08 exynos_cpu_resume_ns System suspend
0x0c 0x00000bad (Magic cookie) System suspend
0x1c exynos4_secondary_startup Secondary CPU boot
0x1c + 4*cpu exynos4_secondary_startup (Exynos4412) Secondary CPU boot
0x20 0xfcba0d10 (Magic cookie) AFTR
0x24 exynos_cpu_resume_ns AFTR
0x28 + 4*cpu 0x8 (Magic cookie, Exynos3250) AFTR
2. Secure mode
Address: sysram_base_addr
Offset Value Purpose
=============================================================================
0x00 exynos4_secondary_startup Secondary CPU boot
0x04 exynos4_secondary_startup (Exynos542x) Secondary CPU boot
4*cpu exynos4_secondary_startup (Exynos4412) Secondary CPU boot
0x20 exynos_cpu_resume (Exynos4210 r1.0) AFTR
0x24 0xfcba0d10 (Magic cookie, Exynos4210 r1.0) AFTR
Address: pmu_base_addr
Offset Value Purpose
=============================================================================
0x0800 exynos_cpu_resume AFTR
0x0814 exynos4_secondary_startup (Exynos4210 r1.1) Secondary CPU boot
0x0818 0xfcba0d10 (Magic cookie, Exynos4210 r1.1) AFTR
0x081C exynos_cpu_resume (Exynos4210 r1.1) AFTR
3. Other (regardless of secure/non-secure mode)
Address: pmu_base_addr
Offset Value Purpose
=============================================================================
0x0908 Non-zero (only Exynos3250) Secondary CPU boot up indicator