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/openbmc/linux/drivers/clk/samsung/
H A Dclk-exynos850.cbf3a4c51 Tue Aug 09 06:33:20 CDT 2022 Sam Protsenko <semen.protsenko@linaro.org> clk: samsung: exynos850: Implement CMU_IS domain

CMU_IS clock domain provides clocks for IS IP-core (Image Signal
Processing Subsystem). According to Exynos850 TRM, CMU_IS generates
CSIS, IPP, ITP, VRA and GDC clocks for BLK_IS.

This patch adds next clocks:
- bus clocks in CMU_TOP needed for CMU_IS
- all internal CMU_IS clocks
- leaf clocks for IS IP-core, CSIS (Camera Serial Interface Slave),
D_TZPC (TrustZone Protection Controller), CSIS DMA, GDC (Geometric
Distortion Correction), IPP (Image Preprocessing Processing core),
ITP (Image Texture Processing core), MCSC (Multi-Channel Scaler),
VRA (Visual Recognition Accelerator), PPMU (Platform Performance
Monitoring Unit), SysMMU and SysReg

IS related gate clocks in CMU_TOP were marked as CLK_IS_CRITICAL,
because:
1. All of those have to be enabled in order to read
/sys/kernel/debug/clk/clk_summary file
2. When some user driver (e.g. exynos-sysmmu) disables some derived
leaf clock, it can lead to CMU_TOP clocks disable, which then makes
the system hang. To prevent that, the CLK_IS_CRITICAL flag is used,
as CLK_IGNORE_UNUSED is not enough.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220809113323.29965-7-semen.protsenko@linaro.org