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Documentation: EXYNOS: Update bootloader interface on exynos542x

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Update the documentation about:
1. Usage of PMU_SPARE2 register.
   Bootloaders on Exynos542x-based boards often use the register
   PMU_SPARE2 (0x908) in the same way as on Exynos3250: as a indicator
   the secondary CPU was booted on. The bootloader will set this value
   to non-zero, after sucessfull power up of secondary CPU. In the same
   time this booted CPU will stuck (spin) waiting for software reset.
2. Exynos542x entry address for secondary CPU boot up after system
   suspend (with MCPM enabled and in non-secure mode).

See arch/arm/mach-exynos/mcpm-exynos.c for source code.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Kukjin Kim <kgene@kernel.org>
This commit is contained in:
Krzysztof Kozlowski 2015-10-24 04:43:31 +09:00 committed by Kukjin Kim
parent 4dddfb8823
commit 97d5c7a77e
1 changed files with 3 additions and 2 deletions
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5
Documentation/arm/Samsung/Bootloader-interface.txt
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@ -19,7 +19,7 @@ executing kernel.
Address: sysram_ns_base_addr
Offset Value Purpose
=============================================================================
0x08 exynos_cpu_resume_ns System suspend
0x08 exynos_cpu_resume_ns, mcpm_entry_point 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
@ -56,7 +56,8 @@ Offset Value Purpose
Address: pmu_base_addr
Offset Value Purpose
=============================================================================
0x0908 Non-zero (only Exynos3250) Secondary CPU boot up indicator
0x0908 Non-zero Secondary CPU boot up indicator
on Exynos3250 and Exynos542x
4. Glossary