Commit e366fdd7 authored by James Hogan's avatar James Hogan Committed by Mike Turquette
Browse files

clk: clk-mux: implement remuxing on set_rate 



Implement clk-mux remuxing if the CLK_SET_RATE_NO_REPARENT flag isn't
set. This implements determine_rate for clk-mux to propagate to each
parent and to choose the best one (like clk-divider this chooses the
parent which provides the fastest rate <= the requested rate).

The determine_rate op is implemented as a core helper function so that
it can be easily used by more complex clocks which incorporate muxes.

Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
Reviewed-by: default avatarStephen Boyd <sboyd@codeaurora.org>
Cc: Mike Turquette <mturquette@linaro.org>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: default avatarMike Turquette <mturquette@linaro.org>
parent 819c1de3

drivers/clk/clk-mux.c

+1 −0
Original line number Diff line number Diff line
@@ -104,6 +104,7 @@ static int clk_mux_set_parent(struct clk_hw *hw, u8 index) 
const struct clk_ops clk_mux_ops = {

	.get_parent = clk_mux_get_parent,

	.set_parent = clk_mux_set_parent,

	.determine_rate = __clk_mux_determine_rate,

};

EXPORT_SYMBOL_GPL(clk_mux_ops);

drivers/clk/clk.c

+49 −0
Original line number Diff line number Diff line
@@ -692,6 +692,55 @@ struct clk *__clk_lookup(const char *name) 
	return NULL;

}



/*

 * Helper for finding best parent to provide a given frequency. This can be used

 * directly as a determine_rate callback (e.g. for a mux), or from a more

 * complex clock that may combine a mux with other operations.

 */

long __clk_mux_determine_rate(struct clk_hw *hw, unsigned long rate,

			      unsigned long *best_parent_rate,

			      struct clk **best_parent_p)

{

	struct clk *clk = hw->clk, *parent, *best_parent = NULL;

	int i, num_parents;

	unsigned long parent_rate, best = 0;



	/* if NO_REPARENT flag set, pass through to current parent */

	if (clk->flags & CLK_SET_RATE_NO_REPARENT) {

		parent = clk->parent;

		if (clk->flags & CLK_SET_RATE_PARENT)

			best = __clk_round_rate(parent, rate);

		else if (parent)

			best = __clk_get_rate(parent);

		else

			best = __clk_get_rate(clk);

		goto out;

	}



	/* find the parent that can provide the fastest rate <= rate */

	num_parents = clk->num_parents;

	for (i = 0; i < num_parents; i++) {

		parent = clk_get_parent_by_index(clk, i);

		if (!parent)

			continue;

		if (clk->flags & CLK_SET_RATE_PARENT)

			parent_rate = __clk_round_rate(parent, rate);

		else

			parent_rate = __clk_get_rate(parent);

		if (parent_rate <= rate && parent_rate > best) {

			best_parent = parent;

			best = parent_rate;

		}

	}



out:

	if (best_parent)

		*best_parent_p = best_parent;

	*best_parent_rate = best;



	return best;

}



/***        clk api        ***/



void __clk_unprepare(struct clk *clk)

include/linux/clk-provider.h

+3 −0
Original line number Diff line number Diff line
@@ -436,6 +436,9 @@ unsigned long __clk_get_flags(struct clk *clk); 
bool __clk_is_prepared(struct clk *clk);

bool __clk_is_enabled(struct clk *clk);

struct clk *__clk_lookup(const char *name);

long __clk_mux_determine_rate(struct clk_hw *hw, unsigned long rate,

			      unsigned long *best_parent_rate,

			      struct clk **best_parent_p);



/*

 * FIXME clock api without lock protection

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