Commit e373315d authored by Frank Oltmanns's avatar Frank Oltmanns Committed by Chen-Yu Tsai
Browse files

clk: sunxi-ng: Add helper function to find closest rate 



The default behaviour of clocks in the sunxi-ng driver is to select a
clock rate that is closest to but less than the requested rate.

Add the ccu_is_better_rate() helper function that - depending on the
fact if thc CCU_FEATURE_CLOSEST_RATE flag is set - decides if a rate is
closer than another rate.

Acked-by: default avatarMaxime Ripard <mripard@kernel.org>
Reviewed-by: default avatarJernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: default avatarFrank Oltmanns <frank@oltmanns.dev>
Link: https://lore.kernel.org/r/20230807-pll-mipi_set_rate_parent-v6-5-f173239a4b59@oltmanns.dev


Signed-off-by: default avatarChen-Yu Tsai <wens@csie.org>
parent 48fb70cd

drivers/clk/sunxi-ng/ccu_common.c

+12 −0
Original line number Diff line number Diff line
@@ -39,6 +39,18 @@ void ccu_helper_wait_for_lock(struct ccu_common *common, u32 lock) 
}

EXPORT_SYMBOL_NS_GPL(ccu_helper_wait_for_lock, SUNXI_CCU);



bool ccu_is_better_rate(struct ccu_common *common,

			unsigned long target_rate,

			unsigned long current_rate,

			unsigned long best_rate)

{

	if (common->features & CCU_FEATURE_CLOSEST_RATE)

		return abs(current_rate - target_rate) < abs(best_rate - target_rate);



	return current_rate <= target_rate && current_rate > best_rate;

}

EXPORT_SYMBOL_NS_GPL(ccu_is_better_rate, SUNXI_CCU);



/*

 * This clock notifier is called when the frequency of a PLL clock is

 * changed. In common PLL designs, changes to the dividers take effect

drivers/clk/sunxi-ng/ccu_common.h

+5 −0
Original line number Diff line number Diff line
@@ -53,6 +53,11 @@ struct sunxi_ccu_desc { 


void ccu_helper_wait_for_lock(struct ccu_common *common, u32 lock);



bool ccu_is_better_rate(struct ccu_common *common,

			unsigned long target_rate,

			unsigned long current_rate,

			unsigned long best_rate);



struct ccu_pll_nb {

	struct notifier_block	clk_nb;

	struct ccu_common	*common;