[PATCH] clk: factor: calculate rate by do_div

[Haojian Zhuang]

clk->rate = parent->rate / div * mult

The formula is OK. But it may overflow while we do operate with
unsigned long. So use do_div instead.

Signed-off-by: Haojian Zhuang <haojian.zhuang at gmail.com>
---
 drivers/clk/clk-fixed-factor.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/clk-fixed-factor.c b/drivers/clk/clk-fixed-factor.c
index a489985..1ef271e 100644
--- a/drivers/clk/clk-fixed-factor.c
+++ b/drivers/clk/clk-fixed-factor.c
@@ -28,8 +28,11 @@ static unsigned long clk_factor_recalc_rate(struct clk_hw *hw,
 		unsigned long parent_rate)
 {
 	struct clk_fixed_factor *fix = to_clk_fixed_factor(hw);
+	unsigned long long int rate;
 
-	return parent_rate * fix->mult / fix->div;
+	rate = (unsigned long long int)parent_rate * fix->mult;
+	do_div(rate, fix->div);
+	return (unsigned long)rate;
 }
 
 static long clk_factor_round_rate(struct clk_hw *hw, unsigned long rate,
-- 
1.7.10.4