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| author | Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com> | 2023-09-29 07:38:52 +0200 |
|---|---|---|
| committer | Geert Uytterhoeven <geert+renesas@glider.be> | 2023-10-05 13:45:19 +0200 |
| commit | a2b23159499efd36b2d63b3c4534075d12ddc97a (patch) | |
| tree | d78a429ebe40397a0f8ab286f57c7230c7965e86 /drivers/clk/renesas | |
| parent | clk: renesas: rzg2l: Trust value returned by hardware (diff) | |
| download | linux-a2b23159499efd36b2d63b3c4534075d12ddc97a.tar.xz linux-a2b23159499efd36b2d63b3c4534075d12ddc97a.zip | |
clk: renesas: rzg2l: Fix computation formula
According to the hardware manual for RZ/G2L
(r01uh0914ej0130-rzg2l-rzg2lc.pdf), the computation formula for PLL rate
is as follows:
Fout = ((m + k/65536) * Fin) / (p * 2^s)
and k has values in the range [-32768, 32767]. Dividing k by 65536 with
integer arithmetic gives zero all the time, causing slight differences
b/w what has been set vs. what is displayed. Thus, get rid of this and
decompose the formula before dividing k by 65536.
Fixes: ef3c613ccd68a ("clk: renesas: Add CPG core wrapper for RZ/G2L SoC")
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20230929053915.1530607-6-claudiu.beznea@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Diffstat (limited to 'drivers/clk/renesas')
| -rw-r--r-- | drivers/clk/renesas/rzg2l-cpg.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/drivers/clk/renesas/rzg2l-cpg.c b/drivers/clk/renesas/rzg2l-cpg.c index 6f50f0329ecf..a4723dd3a070 100644 --- a/drivers/clk/renesas/rzg2l-cpg.c +++ b/drivers/clk/renesas/rzg2l-cpg.c @@ -42,7 +42,7 @@ #define GET_SHIFT(val) ((val >> 12) & 0xff) #define GET_WIDTH(val) ((val >> 8) & 0xf) -#define KDIV(val) FIELD_GET(GENMASK(31, 16), val) +#define KDIV(val) ((s16)FIELD_GET(GENMASK(31, 16), val)) #define MDIV(val) FIELD_GET(GENMASK(15, 6), val) #define PDIV(val) FIELD_GET(GENMASK(5, 0), val) #define SDIV(val) FIELD_GET(GENMASK(2, 0), val) @@ -695,18 +695,18 @@ static unsigned long rzg2l_cpg_pll_clk_recalc_rate(struct clk_hw *hw, struct pll_clk *pll_clk = to_pll(hw); struct rzg2l_cpg_priv *priv = pll_clk->priv; unsigned int val1, val2; - unsigned int mult = 1; - unsigned int div = 1; + u64 rate; if (pll_clk->type != CLK_TYPE_SAM_PLL) return parent_rate; val1 = readl(priv->base + GET_REG_SAMPLL_CLK1(pll_clk->conf)); val2 = readl(priv->base + GET_REG_SAMPLL_CLK2(pll_clk->conf)); - mult = MDIV(val1) + KDIV(val1) / 65536; - div = PDIV(val1) << SDIV(val2); - return DIV_ROUND_CLOSEST_ULL((u64)parent_rate * mult, div); + rate = mul_u64_u32_shr(parent_rate, (MDIV(val1) << 16) + KDIV(val1), + 16 + SDIV(val2)); + + return DIV_ROUND_CLOSEST_ULL(rate, PDIV(val1)); } static const struct clk_ops rzg2l_cpg_pll_ops = { |