[PATCH 1/3] clk: divider: Fix best div calculation for power-of-two and table dividers

From: Maxime COQUELIN
Date: Wed Jan 29 2014 - 11:48:35 EST


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.

Signed-off-by: Maxime Coquelin <maxime.coquelin@xxxxxx>
---
drivers/clk/clk-divider.c | 37 ++++++++++++++++++++++++++++++++++++-
1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
index 5543b7d..2137d58 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 = parent_rate / rate;
+
+ if (!_is_valid_div(divider, div))
+ return -EINVAL;
+
value = _get_val(divider, div);

if (value > div_mask(divider))
--
1.7.9.5

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