Commit c2152d0e authored by Alex Elder's avatar Alex Elder Committed by Mike Turquette
Browse files

clk: bcm/kona: implement determine_rate() 



Implement the clk->determine_rate method for Broadcom Kona peripheral
clocks.  This allows a peripheral clock to be re-parented in order to
satisfy a rate change request.  This takes the place of the previous
kona_peri_clk_round_rate() functionality, though that function remains
because it is used by the new one.

The parent clock that allows the peripheral clock to produce a rate
closest to the one requested is the one selected, though the current
parent is used by default.

Signed-off-by: default avatarAlex Elder <elder@linaro.org>
Signed-off-by: default avatarMike Turquette <mturquette@linaro.org>
parent 63a00269

drivers/clk/bcm/clk-kona.c

+53 −1
Original line number Diff line number Diff line
@@ -1031,6 +1031,58 @@ static long kona_peri_clk_round_rate(struct clk_hw *hw, unsigned long rate, 
				rate ? rate : 1, *parent_rate, NULL);

}



static long kona_peri_clk_determine_rate(struct clk_hw *hw, unsigned long rate,

		unsigned long *best_parent_rate, struct clk **best_parent)

{

	struct kona_clk *bcm_clk = to_kona_clk(hw);

	struct clk *clk = hw->clk;

	struct clk *current_parent;

	unsigned long parent_rate;

	unsigned long best_delta;

	unsigned long best_rate;

	u32 parent_count;

	u32 which;



	/*

	 * If there is no other parent to choose, use the current one.

	 * Note:  We don't honor (or use) CLK_SET_RATE_NO_REPARENT.

	 */

	WARN_ON_ONCE(bcm_clk->init_data.flags & CLK_SET_RATE_NO_REPARENT);

	parent_count = (u32)bcm_clk->init_data.num_parents;

	if (parent_count < 2)

		return kona_peri_clk_round_rate(hw, rate, best_parent_rate);



	/* Unless we can do better, stick with current parent */

	current_parent = clk_get_parent(clk);

	parent_rate = __clk_get_rate(current_parent);

	best_rate = kona_peri_clk_round_rate(hw, rate, &parent_rate);

	best_delta = abs(best_rate - rate);



	/* Check whether any other parent clock can produce a better result */

	for (which = 0; which < parent_count; which++) {

		struct clk *parent = clk_get_parent_by_index(clk, which);

		unsigned long delta;

		unsigned long other_rate;



		BUG_ON(!parent);

		if (parent == current_parent)

			continue;



		/* We don't support CLK_SET_RATE_PARENT */

		parent_rate = __clk_get_rate(parent);

		other_rate = kona_peri_clk_round_rate(hw, rate, &parent_rate);

		delta = abs(other_rate - rate);

		if (delta < best_delta) {

			best_delta = delta;

			best_rate = other_rate;

			*best_parent = parent;

			*best_parent_rate = parent_rate;

		}

	}



	return best_rate;

}



static int kona_peri_clk_set_parent(struct clk_hw *hw, u8 index)

{

	struct kona_clk *bcm_clk = to_kona_clk(hw);
@@ -1135,7 +1187,7 @@ struct clk_ops kona_peri_clk_ops = { 
	.disable = kona_peri_clk_disable,

	.is_enabled = kona_peri_clk_is_enabled,

	.recalc_rate = kona_peri_clk_recalc_rate,

	.round_rate = kona_peri_clk_round_rate,

	.determine_rate = kona_peri_clk_determine_rate,

	.set_parent = kona_peri_clk_set_parent,

	.get_parent = kona_peri_clk_get_parent,

	.set_rate = kona_peri_clk_set_rate,

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