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authorJean-Jacques Hiblot <jjhiblot@traphandler.com>2014-03-11 13:00:35 +0400
committerMike Turquette <mturquette@linaro.org>2014-03-20 02:22:02 +0400
commit141c71dd2c00ca7d807138ece55a17c61085c793 (patch)
tree6fd154b0dce3f7f5cb3d51c7a9244bfce459f67d /drivers/clk/at91
parentcce6db80a049b23f867f4afded70ca8027876a08 (diff)
downloadlinux-141c71dd2c00ca7d807138ece55a17c61085c793.tar.xz
clk: at91: optimization of the set_rate callback
Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com> Signed-off-by: Jean-Jacques Hiblot <jjhiblot@traphandler.com> Signed-off-by: Mike Turquette <mturquette@linaro.org>
Diffstat (limited to 'drivers/clk/at91')
-rw-r--r--drivers/clk/at91/clk-programmable.c38
1 files changed, 8 insertions, 30 deletions
diff --git a/drivers/clk/at91/clk-programmable.c b/drivers/clk/at91/clk-programmable.c
index 7bcc725f67af..62e2509f9df1 100644
--- a/drivers/clk/at91/clk-programmable.c
+++ b/drivers/clk/at91/clk-programmable.c
@@ -139,43 +139,21 @@ static int clk_programmable_set_rate(struct clk_hw *hw, unsigned long rate,
struct clk_programmable *prog = to_clk_programmable(hw);
struct at91_pmc *pmc = prog->pmc;
const struct clk_programmable_layout *layout = prog->layout;
- unsigned long best_rate = parent_rate;
- unsigned long best_diff;
- unsigned long new_diff;
- unsigned long cur_rate;
+ unsigned long div = parent_rate / rate;
int shift = 0;
u32 tmp = pmc_read(pmc, AT91_PMC_PCKR(prog->id)) &
~(PROG_PRES_MASK << layout->pres_shift);
- if (rate > parent_rate)
- return parent_rate;
- else
- best_diff = parent_rate - rate;
+ if (!div)
+ return -EINVAL;
- if (!best_diff) {
- pmc_write(pmc, AT91_PMC_PCKR(prog->id), tmp | shift);
- return 0;
- }
-
- for (shift = 1; shift < PROG_PRES_MASK; shift++) {
- cur_rate = parent_rate >> shift;
-
- if (cur_rate > rate)
- new_diff = cur_rate - rate;
- else
- new_diff = rate - cur_rate;
-
- if (!new_diff)
- break;
+ shift = fls(div) - 1;
- if (new_diff < best_diff) {
- best_diff = new_diff;
- best_rate = cur_rate;
- }
+ if (div != (1<<shift))
+ return -EINVAL;
- if (rate > cur_rate)
- break;
- }
+ if (shift >= PROG_PRES_MASK)
+ return -EINVAL;
pmc_write(pmc, AT91_PMC_PCKR(prog->id),
tmp | (shift << layout->pres_shift));