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authorJerome Brunet <jbrunet@baylibre.com>2018-02-19 12:21:41 +0100
committerNeil Armstrong <narmstrong@baylibre.com>2018-03-13 10:09:49 +0100
commit0a1be867b92a5afb93bce62e12ef76b7c2b777fd (patch)
treeeec860f0aa566ddee431d99b07149c2c65d64ef5 /drivers/clk/meson
parentc77de0e5c95a249fd2d4105dbc619f436ec96345 (diff)
clk: meson: add ROUND_CLOSEST to the pll driver
Provide an option for the pll driver to round to the rate closest to the requested rate, instead of systematically rounding down. This may allow the provided rate to be closer to the requested rate when rounding up is not an issue Signed-off-by: Jerome Brunet <jbrunet@baylibre.com> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Diffstat (limited to 'drivers/clk/meson')
-rw-r--r--drivers/clk/meson/clk-pll.c17
-rw-r--r--drivers/clk/meson/clkc.h2
2 files changed, 15 insertions, 4 deletions
diff --git a/drivers/clk/meson/clk-pll.c b/drivers/clk/meson/clk-pll.c
index d58961f35b71..65a7bd903551 100644
--- a/drivers/clk/meson/clk-pll.c
+++ b/drivers/clk/meson/clk-pll.c
@@ -105,7 +105,12 @@ static u16 __pll_params_with_frac(unsigned long rate,
u64 val = (u64)rate * pllt->n;
val <<= pllt->od + pllt->od2 + pllt->od3;
- val = div_u64(val * frac_max, parent_rate);
+
+ if (pll->flags & CLK_MESON_PLL_ROUND_CLOSEST)
+ val = DIV_ROUND_CLOSEST_ULL(val * frac_max, parent_rate);
+ else
+ val = div_u64(val * frac_max, parent_rate);
+
val -= pllt->m * frac_max;
return min((u16)val, (u16)(frac_max - 1));
@@ -125,9 +130,13 @@ meson_clk_get_pll_settings(unsigned long rate,
while (table[i].rate && table[i].rate <= rate)
i++;
- /* Select the setting of the rounded down rate */
- if (i != 0)
- i--;
+ if (i != 0) {
+ if (MESON_PARM_APPLICABLE(&pll->frac) ||
+ !(pll->flags & CLK_MESON_PLL_ROUND_CLOSEST) ||
+ (abs(rate - table[i - 1].rate) <
+ abs(rate - table[i].rate)))
+ i--;
+ }
return (struct pll_rate_table *)&table[i];
}
diff --git a/drivers/clk/meson/clkc.h b/drivers/clk/meson/clkc.h
index 9cdcd9b6c16c..8fe73c4edca8 100644
--- a/drivers/clk/meson/clkc.h
+++ b/drivers/clk/meson/clkc.h
@@ -71,6 +71,8 @@ struct pll_rate_table {
.od = (_od), \
}
+#define CLK_MESON_PLL_ROUND_CLOSEST BIT(0)
+
struct meson_clk_pll_data {
struct parm m;
struct parm n;