Various boot loaders for Exynos based boards use certain memory addresses during booting for different purposes. Mostly this is one of following : 1. as a CPU boot address, 2. for storing magic cookie related to low power mode (AFTR, sleep). The document, based solely on kernel source code, tries to group the information scattered over different files. This would help in the future when adding support for new SoC or when extending features related to low power modes. Signed-off-by: Krzysztof Kozlowski <k.kozlowski.k@xxxxxxxxx> --- Documentation/arm/Samsung/Bootloader-interface.txt | 53 ++++++++++++++++++++++ 1 file changed, 53 insertions(+) create mode 100644 Documentation/arm/Samsung/Bootloader-interface.txt diff --git a/Documentation/arm/Samsung/Bootloader-interface.txt b/Documentation/arm/Samsung/Bootloader-interface.txt new file mode 100644 index 000000000000..b96ead9a6919 --- /dev/null +++ b/Documentation/arm/Samsung/Bootloader-interface.txt @@ -0,0 +1,53 @@ + 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 -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
