Add a new clock flag called CLK_SET_RATE_REMUX to indicate that the clock can have it's parent changed automatically in response to a set_rate.
Implement clk-mux remuxing if the CLK_SET_RATE_REMUX flag is 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 <[email protected]> --- drivers/clk/clk-mux.c | 1 + drivers/clk/clk.c | 49 ++++++++++++++++++++++++++++++++++++++++++++ include/linux/clk-provider.h | 4 ++++ 3 files changed, 54 insertions(+) diff --git a/drivers/clk/clk-mux.c b/drivers/clk/clk-mux.c index 508c032..3a42b96 100644 --- a/drivers/clk/clk-mux.c +++ b/drivers/clk/clk-mux.c @@ -85,6 +85,7 @@ 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); diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index cc0e618..8c4b714 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -529,6 +529,55 @@ 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 remux flag not set, pass through to current parent */ + if (!(clk->flags & CLK_SET_RATE_REMUX)) { + 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_p && best_parent) + *best_parent_p = best_parent; + *best_parent_rate = best; + + return best; +} + /*** clk api ***/ void __clk_unprepare(struct clk *clk) diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h index 5fe1d38..0eb4532 100644 --- a/include/linux/clk-provider.h +++ b/include/linux/clk-provider.h @@ -27,6 +27,7 @@ #define CLK_IS_ROOT BIT(4) /* root clk, has no parent */ #define CLK_IS_BASIC BIT(5) /* Basic clk, can't do a to_clk_foo() */ #define CLK_GET_RATE_NOCACHE BIT(6) /* do not use the cached clk rate */ +#define CLK_SET_RATE_REMUX BIT(7) /* find best parent for rate change */ struct clk_hw; @@ -361,6 +362,9 @@ unsigned long __clk_get_rate(struct clk *clk); unsigned long __clk_get_flags(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 -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
