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1 Interface between kernel and boot loaders on Exynos boards
2 ==========================================================
3
4Author: Krzysztof Kozlowski
5Date : 6 June 2015
6
7The document tries to describe currently used interface between Linux kernel
8and boot loaders on Samsung Exynos based boards. This is not a definition
9of interface but rather a description of existing state, a reference
10for information purpose only.
11
12In the document "boot loader" means any of following: U-boot, proprietary
13SBOOT or any other firmware for ARMv7 and ARMv8 initializing the board before
14executing kernel.
15
16
171. Non-Secure mode
18
19Address: sysram_ns_base_addr
20Offset Value Purpose
21=============================================================================
220x08 exynos_cpu_resume_ns, mcpm_entry_point System suspend
230x0c 0x00000bad (Magic cookie) System suspend
240x1c exynos4_secondary_startup Secondary CPU boot
250x1c + 4*cpu exynos4_secondary_startup (Exynos4412) Secondary CPU boot
260x20 0xfcba0d10 (Magic cookie) AFTR
270x24 exynos_cpu_resume_ns AFTR
280x28 + 4*cpu 0x8 (Magic cookie, Exynos3250) AFTR
290x28 0x0 or last value during resume (Exynos542x) System suspend
30
31
322. Secure mode
33
34Address: sysram_base_addr
35Offset Value Purpose
36=============================================================================
370x00 exynos4_secondary_startup Secondary CPU boot
380x04 exynos4_secondary_startup (Exynos542x) Secondary CPU boot
394*cpu exynos4_secondary_startup (Exynos4412) Secondary CPU boot
400x20 exynos_cpu_resume (Exynos4210 r1.0) AFTR
410x24 0xfcba0d10 (Magic cookie, Exynos4210 r1.0) AFTR
42
43Address: pmu_base_addr
44Offset Value Purpose
45=============================================================================
460x0800 exynos_cpu_resume AFTR, suspend
470x0800 mcpm_entry_point (Exynos542x with MCPM) AFTR, suspend
480x0804 0xfcba0d10 (Magic cookie) AFTR
490x0804 0x00000bad (Magic cookie) System suspend
500x0814 exynos4_secondary_startup (Exynos4210 r1.1) Secondary CPU boot
510x0818 0xfcba0d10 (Magic cookie, Exynos4210 r1.1) AFTR
520x081C exynos_cpu_resume (Exynos4210 r1.1) AFTR
53
54
553. Other (regardless of secure/non-secure mode)
56
57Address: pmu_base_addr
58Offset Value Purpose
59=============================================================================
600x0908 Non-zero Secondary CPU boot up indicator
61 on Exynos3250 and Exynos542x
62
63
644. Glossary
65
66AFTR - ARM Off Top Running, a low power mode, Cortex cores and many other
67modules are power gated, except the TOP modules
68MCPM - Multi-Cluster Power Management