dedf87341a
Implement support for CPU clock management units:
- CMU_CPUCL0: clocks for cluster 0: 4 x Cortex-A55 (cpu0..cpu3)
- CMU_CPUCL1: clocks for cluster 1: 4 x Cortex-A55 (cpu4..cpu7)
CPU PLLs are generating main CPU clocks for each cluster, and there are
alternate ("switch") clocks that can be used temporarily while
re-configuring the PLL for a new rate. ACLK, ATCLK, PCLKDBG and
PERIPHCLK clocks are driving corresponding buses. CLK_CLUSTERx_SCLK are
actual leaf CPU clocks and should be used to change CPU rates. Also some
CoreSight clocks can be derived from DBG_USER (debug clock).
PLL table was extracted from ECT table. ECT stands for "Exynos
Characteristic Table", it's a Samsung specific binary data populated by
BL2 bootloader in RAM at 0x90000000 address, containing PLL tables for
various CMUs and other hardware specific information.
The particular PLL type used in CMU_CPUCL0 and CMU_CPUCL1 (pll0822x) is
an integer PLL with middle FVCO. The equation to calculate its output
rate is:
fout = fin * M / (P*2^S)
where:
fin = 26 MHz (OSCCLK frequency)
M = 64..1023
P = 1..63
S = 0..6
The PLL table tries to keep "P" value low to reduce the locking time,
which for pll0822x is "t = P * 150" (in OSCCLK cycles).
Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Link: https://lore.kernel.org/r/20240301015118.30072-2-semen.protsenko@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Linux kernel
============
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In order to build the documentation, use ``make htmldocs`` or
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There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
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the problems which may result by upgrading your kernel.