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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: James Hogan <james.hogan@imgtec.com> Reviewed-by: Stephen Boyd <sboyd@codeaurora.org> Cc: Mike Turquette <mturquette@linaro.org> Cc: linux-arm-kernel@lists.infradead.org Signed-off-by: Mike Turquette <mturquette@linaro.org>
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@ -104,6 +104,7 @@ static int clk_mux_set_parent(struct clk_hw *hw, u8 index)
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const struct clk_ops clk_mux_ops = {
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.get_parent = clk_mux_get_parent,
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.set_parent = clk_mux_set_parent,
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.determine_rate = __clk_mux_determine_rate,
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};
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EXPORT_SYMBOL_GPL(clk_mux_ops);
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@ -692,6 +692,55 @@ struct clk *__clk_lookup(const char *name)
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return NULL;
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}
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/*
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* Helper for finding best parent to provide a given frequency. This can be used
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* directly as a determine_rate callback (e.g. for a mux), or from a more
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* complex clock that may combine a mux with other operations.
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*/
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long __clk_mux_determine_rate(struct clk_hw *hw, unsigned long rate,
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unsigned long *best_parent_rate,
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struct clk **best_parent_p)
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{
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struct clk *clk = hw->clk, *parent, *best_parent = NULL;
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int i, num_parents;
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unsigned long parent_rate, best = 0;
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/* if NO_REPARENT flag set, pass through to current parent */
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if (clk->flags & CLK_SET_RATE_NO_REPARENT) {
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parent = clk->parent;
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if (clk->flags & CLK_SET_RATE_PARENT)
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best = __clk_round_rate(parent, rate);
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else if (parent)
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best = __clk_get_rate(parent);
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else
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best = __clk_get_rate(clk);
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goto out;
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}
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/* find the parent that can provide the fastest rate <= rate */
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num_parents = clk->num_parents;
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for (i = 0; i < num_parents; i++) {
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parent = clk_get_parent_by_index(clk, i);
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if (!parent)
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continue;
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if (clk->flags & CLK_SET_RATE_PARENT)
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parent_rate = __clk_round_rate(parent, rate);
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else
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parent_rate = __clk_get_rate(parent);
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if (parent_rate <= rate && parent_rate > best) {
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best_parent = parent;
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best = parent_rate;
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}
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}
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out:
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if (best_parent)
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*best_parent_p = best_parent;
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*best_parent_rate = best;
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return best;
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}
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/*** clk api ***/
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void __clk_unprepare(struct clk *clk)
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@ -436,6 +436,9 @@ unsigned long __clk_get_flags(struct clk *clk);
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bool __clk_is_prepared(struct clk *clk);
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bool __clk_is_enabled(struct clk *clk);
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struct clk *__clk_lookup(const char *name);
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long __clk_mux_determine_rate(struct clk_hw *hw, unsigned long rate,
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unsigned long *best_parent_rate,
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struct clk **best_parent_p);
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/*
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* FIXME clock api without lock protection
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