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clk: fixed-factor: round_rate should use do_div

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@gmail.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
[mturquette@linaro.org: improved $SUBJECT]
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1 parent 4895084 commit bab53301c3846ae9a5e1142dca2976f434f70481 @hzhuang1 hzhuang1 committed with Mike Turquette Dec 3, 2012
Showing with 4 additions and 1 deletion.
  1. +4 −1 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,

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