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Commit 141c71dd authored by Jean-Jacques Hiblot's avatar Jean-Jacques Hiblot Committed by Mike Turquette
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clk: at91: optimization of the set_rate callback 



Signed-off-by: default avatarBoris BREZILLON <b.brezillon@overkiz.com>
Signed-off-by: default avatarJean-Jacques Hiblot <jjhiblot@traphandler.com>
Signed-off-by: default avatarMike Turquette <mturquette@linaro.org>
parent cce6db80

drivers/clk/at91/clk-programmable.c

+8 −30
Original line number Diff line number Diff line
@@ -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 (!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 (!div)

		return -EINVAL;



		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));