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>
Extend the kernel-bootloader interface documentation with usage of
register INFORM1 (0x0804) and different CPU resume address on Exynos542x
family (with Multi-Cluster Power Management enabled).
Additionally add glossary and reformat section titles.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski.k@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
