[PATCH 1/2] clk: meson: mpll: add round closest support

[Jerome Brunet]

Allow the mpll driver to round the requested rate up if
CLK_MESON_MPLL_ROUND_CLOSEST is set and it provides a rate closer to the
requested rate.

Signed-off-by: Jerome Brunet <jbru...@baylibre.com>
---
 drivers/clk/meson/clk-mpll.c | 25 ++++++++++++++++++++-----
 drivers/clk/meson/clkc.h     |  3 +++
 2 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/drivers/clk/meson/clk-mpll.c b/drivers/clk/meson/clk-mpll.c
index 0df1227b65b3..4e5283eb892a 100644
--- a/drivers/clk/meson/clk-mpll.c
+++ b/drivers/clk/meson/clk-mpll.c
@@ -89,10 +89,23 @@ static long rate_from_params(unsigned long parent_rate,
 static void params_from_rate(unsigned long requested_rate,
                             unsigned long parent_rate,
                             unsigned int *sdm,
-                            unsigned int *n2)
+                            unsigned int *n2,
+                            u8 flags)
 {
        uint64_t div = parent_rate;
-       unsigned long rem = do_div(div, requested_rate);
+       uint64_t frac = do_div(div, requested_rate);
+       unsigned long rem;
+
+       frac *= SDM_DEN;
+       rem = do_div(frac, requested_rate);
+
+       /* Should we round up ? */
+       if (flags & CLK_MESON_MPLL_ROUND_CLOSEST
+           && rem > (requested_rate / 2)) {
+               frac = (frac + 1) % SDM_DEN;
+               if (frac == 0)
+                       div += 1;
+       }
 
        if (div < N2_MIN) {
                *n2 = N2_MIN;
@@ -102,7 +115,7 @@ static void params_from_rate(unsigned long requested_rate,
                *sdm = SDM_DEN - 1;
        } else {
                *n2 = div;
-               *sdm = DIV_ROUND_UP_ULL((u64)rem * SDM_DEN, requested_rate);
+               *sdm = frac;
        }
 }
 
@@ -125,9 +138,11 @@ static long mpll_round_rate(struct clk_hw *hw,
                            unsigned long rate,
                            unsigned long *parent_rate)
 {
+       struct clk_regmap *clk = to_clk_regmap(hw);
+       struct meson_clk_mpll_data *mpll = meson_clk_mpll_data(clk);
        unsigned int sdm, n2;
 
-       params_from_rate(rate, *parent_rate, &sdm, &n2);
+       params_from_rate(rate, *parent_rate, &sdm, &n2, mpll->flags);
        return rate_from_params(*parent_rate, sdm, n2);
 }
 
@@ -140,7 +155,7 @@ static int mpll_set_rate(struct clk_hw *hw,
        unsigned int sdm, n2;
        unsigned long flags = 0;
 
-       params_from_rate(rate, parent_rate, &sdm, &n2);
+       params_from_rate(rate, parent_rate, &sdm, &n2, mpll->flags);
 
        if (mpll->lock)
                spin_lock_irqsave(mpll->lock, flags);
diff --git a/drivers/clk/meson/clkc.h b/drivers/clk/meson/clkc.h
index 8fe73c4edca8..8cc265cd3d2b 100644
--- a/drivers/clk/meson/clkc.h
+++ b/drivers/clk/meson/clkc.h
@@ -97,8 +97,11 @@ struct meson_clk_mpll_data {
        struct parm ssen;
        struct parm misc;
        spinlock_t *lock;
+       u8 flags;
 };
 
+#define CLK_MESON_MPLL_ROUND_CLOSEST   BIT(0)
+
 struct meson_clk_audio_div_data {
        struct parm div;
        u8 flags;
-- 
2.14.3