clk: samsung: clk-pll: Implement pll0822x PLL type
authorSam Protsenko <semen.protsenko@linaro.org>
Fri, 8 Oct 2021 15:43:48 +0000 (18:43 +0300)
committerSylwester Nawrocki <s.nawrocki@samsung.com>
Sat, 9 Oct 2021 20:19:58 +0000 (22:19 +0200)
commit8f90f43a095d99144219fd3a5d1d5ddfb250b808
tree98e6d5db1ddd6f2ce31128997f5f0c2eac7ff2d2
parent1d26eaeec37a91ff4575f6fead889818c5895304
clk: samsung: clk-pll: Implement pll0822x PLL type

pll0822x PLL is used in Exynos850 SoC for top-level integer PLLs. The
code was derived from very similar pll35xx type, with next differences:

1. Lock time for pll0822x is 150*P_DIV, when for pll35xx it's 270*P_DIV
2. It's not suggested in Exynos850 TRM that S_DIV change doesn't require
   performing PLL lock procedure (which is done in pll35xx
   implementation)

When defining pll0822x type, CON3 register offset should be provided as
a "con" parameter of PLL() macro, like this:

    PLL(pll_0822x, 0, "fout_shared0_pll", "oscclk",
        PLL_LOCKTIME_PLL_SHARED0, PLL_CON3_PLL_SHARED0,
        exynos850_shared0_pll_rates),

To define PLL rates table, one can use PLL_35XX_RATE() macro, e.g.:

    PLL_35XX_RATE(26 * MHZ, 1600 * MHZ, 800, 13, 0)

as it's completely appropriate for pl0822x type and there is no sense in
duplicating that.

If bit #1 (MANUAL_PLL_CTRL) is not set in CON1 register, it won't be
possible to set new rate, with next error showing in kernel log:

    Could not lock PLL fout_shared1_pll

That can happen for example if bootloader clears that bit beforehand.
PLL driver doesn't account for that, so if MANUAL_PLL_CTRL bit was
cleared, it's assumed it was done for a reason and it shouldn't be
possible to change that PLL's rate at all.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>
Link: https://lore.kernel.org/r/20211008154352.19519-2-semen.protsenko@linaro.org
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
drivers/clk/samsung/clk-pll.c
drivers/clk/samsung/clk-pll.h