clk: divider: Fix best div calculation for power-of-two and table dividers

The divider returned by clk_divider_bestdiv() is likely to be invalid in case
of power-of-two and table dividers when CLK_SET_RATE_PARENT flag isn't set.

Fixes boot on STiH416 platform.

Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
[mturquette@linaro.org: trivial merge conflict & updated changelog]

1 files changed, 36 insertions, 1 deletions

diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
index ec22112e569f..4637697c139f 100644
--- a/drivers/clk/clk-divider.c
+++ b/drivers/clk/clk-divider.c
@@ -144,6 +144,37 @@ static bool _is_valid_div(struct clk_divider *divider, unsigned int div)
         return true;
 }
 
+static int _round_up_table(const struct clk_div_table *table, int div)
+{
+        const struct clk_div_table *clkt;
+        int up = _get_table_maxdiv(table);
+
+        for (clkt = table; clkt->div; clkt++) {
+                if (clkt->div == div)
+                        return clkt->div;
+                else if (clkt->div < div)
+                        continue;
+
+                if ((clkt->div - div) < (up - div))
+                        up = clkt->div;
+        }
+
+        return up;
+}
+
+static int _div_round_up(struct clk_divider *divider,
+                unsigned long parent_rate, unsigned long rate)
+{
+        int div = DIV_ROUND_UP(parent_rate, rate);
+
+        if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)
+                div = __roundup_pow_of_two(div);
+        if (divider->table)
+                div = _round_up_table(divider->table, div);
+
+        return div;
+}
+
 static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
                 unsigned long *best_parent_rate)
 {
@@ -159,7 +190,7 @@ static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
 
         if (!(__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT)) {
                 parent_rate = *best_parent_rate;
-                bestdiv = DIV_ROUND_UP(parent_rate, rate);
+                bestdiv = _div_round_up(divider, parent_rate, rate);
                 bestdiv = bestdiv == 0 ? 1 : bestdiv;
                 bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
                 return bestdiv;
@@ -219,6 +250,10 @@ static int clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
         u32 val;
 
         div = DIV_ROUND_UP(parent_rate, rate);
+
+        if (!_is_valid_div(divider, div))
+                return -EINVAL;
+
         value = _get_val(divider, div);
 
         if (value > div_mask(divider))