linux_dsm_epyc7002/Documentation/arm/Samsung/Bootloader-interface.txt
Krzysztof Kozlowski e0b35c1ab5 ARM: exynos: Fix imprecise abort during Exynos5422 suspend to RAM
Suspend to RAM on Odroid XU3/XU4/HC1 family (Exynos5422) causes
imprecise abort:

	PM: Syncing filesystems ... done.
	Freezing user space processes ... (elapsed 0.003 seconds) done.
	OOM killer disabled.
	Freezing remaining freezable tasks ... (elapsed 0.003 seconds) done.
	wake enabled for irq 139
	Disabling non-boot CPUs ...
	IRQ51 no longer affine to CPU1
	IRQ52 no longer affine to CPU2
	IRQ53 no longer affine to CPU3
	IRQ54 no longer affine to CPU4
	IRQ55 no longer affine to CPU5
	IRQ56 no longer affine to CPU6
	cpu cpu4: Dropping the link to regulator.40
	IRQ57 no longer affine to CPU7
	Unhandled fault: external abort on non-linefetch (0x1008) at 0xf081a028
	Internal error: : 1008 [#1] PREEMPT SMP ARM

with last call trace in exynos_suspend_enter().

The abort is caused by writing to register in secure part of sysram.
Boards booted under secure firmware (e.g. Hardkernel Odroid boards)
should access non-secure sysram.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
2018-08-30 19:46:06 +02:00

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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, 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
0x20 0xfcba0d10 (Magic cookie) AFTR
0x24 exynos_cpu_resume_ns AFTR
0x28 + 4*cpu 0x8 (Magic cookie, Exynos3250) AFTR
0x28 0x0 or last value during resume (Exynos542x) System suspend
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, suspend
0x0800 mcpm_entry_point (Exynos542x with MCPM) AFTR, suspend
0x0804 0xfcba0d10 (Magic cookie) AFTR
0x0804 0x00000bad (Magic cookie) System suspend
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 Secondary CPU boot up indicator
on Exynos3250 and Exynos542x
4. Glossary
AFTR - ARM Off Top Running, a low power mode, Cortex cores and many other
modules are power gated, except the TOP modules
MCPM - Multi-Cluster Power Management