clk: ti: divider: Add the table parsing to get the best divider value

Currently the divider selection logic blindly divides the parent_rate
by the clk rate and gives the divider value for the divider clocks
which do not have the CLK_SET_RATE_PARENT flag set. Add the clk divider
table parsing to get the closest divider available in the table
provided via Device tree.

The code is pretty much taken from: drivers/clk/clk-divider.c.
and used here to fix up the best divider selection logic.

Signed-off-by: Keerthy <j-keerthy@ti.com>
Reported-by: Richard Woodruff <r-woodruff2@ti.com>
Acked-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

diff --git a/drivers/clk/ti/divider.c b/drivers/clk/ti/divider.c
index b4e5de16e561e05a3d2e9ff41d38beb52f48555f..6bb87784a0d6ef82c411bf7ba566412a4059dd20 100644 (file)
--- a/drivers/clk/ti/divider.c
+++ b/drivers/clk/ti/divider.c
@@ -140,6 +140,35 @@ static bool _is_valid_div(struct clk_divider *divider, unsigned int div)
        return true;
 }
 
+static int _div_round_up(const struct clk_div_table *table,
+                        unsigned long parent_rate, unsigned long rate)
+{
+       const struct clk_div_table *clkt;
+       int up = INT_MAX;
+       int div = DIV_ROUND_UP_ULL((u64)parent_rate, rate);
+
+       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(const struct clk_div_table *table,
+                     unsigned long parent_rate, unsigned long rate)
+{
+       if (!table)
+               return DIV_ROUND_UP(parent_rate, rate);
+
+       return _div_round_up(table, parent_rate, rate);
+}
+
 static int ti_clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
                                  unsigned long *best_parent_rate)
 {
@@ -155,7 +184,7 @@ static int ti_clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
 
        if (!(clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT)) {
                parent_rate = *best_parent_rate;
-               bestdiv = DIV_ROUND_UP(parent_rate, rate);
+               bestdiv = _div_round(divider->table, parent_rate, rate);
                bestdiv = bestdiv == 0 ? 1 : bestdiv;
                bestdiv = bestdiv > maxdiv ? maxdiv : bestdiv;
                return bestdiv;