[PATCH RESEND v8 2/2] clk: Add floor and ceiling constraints to clock rates
From: Stephen Boyd <hidden>
Date: 2015-01-17 01:57:07
Also in:
linux-mips, linux-omap, lkml
On 01/12, Tomeu Vizoso wrote:
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diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 7eddfd8..2793bd7 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c@@ -1013,8 +1015,8 @@ static unsigned long clk_core_round_rate_nolock(struct clk_core *clk, if (clk->ops->determine_rate) { parent_hw = parent ? parent->hw : NULL; - return clk->ops->determine_rate(clk->hw, rate, &parent_rate, - &parent_hw); + return clk->ops->determine_rate(clk->hw, rate, 0, ULONG_MAX, + &parent_rate, &parent_hw); } else if (clk->ops->round_rate) return clk->ops->round_rate(clk->hw, rate, &parent_rate); else if (clk->flags & CLK_SET_RATE_PARENT)@@ -1453,8 +1458,20 @@ static struct clk_core *clk_calc_new_rates(struct clk_core *clk, /* find the closest rate and parent clk/rate */ if (clk->ops->determine_rate) { + hlist_for_each_entry(clk_user, &clk->clks, child_node) { + floor_rate = max(floor_rate, + clk_user->floor_constraint); + } + + hlist_for_each_entry(clk_user, &clk->clks, child_node) { + ceiling_rate = min(ceiling_rate, + clk_user->ceiling_constraint); + }
I would think we need to do this in the clk_round_rate() path as well. We can't just pass 0 and ULONG_MAX there or we'll determine one rate here and another rate in round_rate(), violating the contract between set_rate() and round_rate().
+ parent_hw = parent ? parent->hw : NULL; new_rate = clk->ops->determine_rate(clk->hw, rate, + floor_rate, + ceiling_rate, &best_parent_rate, &parent_hw); parent = parent_hw ? parent_hw->core : NULL;
We should enforce a constraint if the clk is using the round_rate() op too. If the .round_rate() op returns some rate within range it should be ok. Otherwise we can fail the rate change because it's out of range. We'll also need to introduce some sort of clk_core_determine_rate(core, rate, min, max) so that clock providers can ask parent clocks to find a rate within some range that they can tolerate. If we update __clk_mux_determine_rate() we can see how that would work out.
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@@ -1660,13 +1657,92 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
[...]
+ */
+int clk_set_rate(struct clk *clk, unsigned long rate)
+{
+ return clk_core_set_rate(clk->core, rate);clk could be NULL.
+}
EXPORT_SYMBOL_GPL(clk_set_rate);
+int clk_set_rate_range(struct clk *clk, unsigned long min, unsigned long max)
+{
+ int ret = 0;Check for NULL clk.
+
+/**
+ * clk_set_floor_rate - set a minimum clock rate for a clock source
+ * @clk: clock source
+ * @rate: desired minimum clock rate in Hz
+ *
+ * Returns success (0) or negative errno.
+ */
+int clk_set_floor_rate(struct clk *clk, unsigned long rate)
+{
+ return clk_set_rate_range(clk, rate, clk->ceiling_constraint);clk could be NULL.
+}
+EXPORT_SYMBOL_GPL(clk_set_floor_rate);
+
+/**
+ * clk_set_ceiling_rate - set a maximum clock rate for a clock source
+ * @clk: clock source
+ * @rate: desired maximum clock rate in Hz
+ *
+ * Returns success (0) or negative errno.
+ */
+int clk_set_ceiling_rate(struct clk *clk, unsigned long rate)
+{
+ return clk_set_rate_range(clk, clk->floor_constraint, rate);clk could be NULL.
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+} +EXPORT_SYMBOL_GPL(clk_set_ceiling_rate); + static struct clk_core *clk_core_get_parent(struct clk_core *core) { struct clk_core *parent;diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h index 2e65419..ae5c800 100644 --- a/include/linux/clk-provider.h +++ b/include/linux/clk-provider.h@@ -175,9 +175,12 @@ struct clk_ops { unsigned long parent_rate); long (*round_rate)(struct clk_hw *hw, unsigned long rate, unsigned long *parent_rate); - long (*determine_rate)(struct clk_hw *hw, unsigned long rate, - unsigned long *best_parent_rate, - struct clk_hw **best_parent_hw); + long (*determine_rate)(struct clk_hw *hw, + unsigned long rate, + unsigned long floor_rate, + unsigned long ceiling_rate,
I wonder if we should call this min_rate and max_rate?
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+ unsigned long *best_parent_rate, + struct clk_hw **best_parent_hw); int (*set_parent)(struct clk_hw *hw, u8 index); u8 (*get_parent)(struct clk_hw *hw); int (*set_rate)(struct clk_hw *hw, unsigned long rate,diff --git a/include/linux/clk.h b/include/linux/clk.h index c7f258a..f99ae67 100644 --- a/include/linux/clk.h +++ b/include/linux/clk.h@@ -302,6 +302,34 @@ long clk_round_rate(struct clk *clk, unsigned long rate); int clk_set_rate(struct clk *clk, unsigned long rate); /** + * clk_set_rate_range - set a rate range for a clock source + * @clk: clock source + * @min: desired minimum clock rate in Hz + * @max: desired maximum clock rate in Hz + * + * Returns success (0) or negative errno. + */ +int clk_set_rate_range(struct clk *clk, unsigned long min, unsigned long max); + +/** + * clk_set_floor_rate - set a minimum clock rate for a clock source + * @clk: clock source + * @rate: desired minimum clock rate in Hz + * + * Returns success (0) or negative errno. + */ +int clk_set_floor_rate(struct clk *clk, unsigned long rate);
And this called clk_set_max_rate()?
+ +/** + * clk_set_ceiling_rate - set a maximum clock rate for a clock source + * @clk: clock source + * @rate: desired maximum clock rate in Hz + * + * Returns success (0) or negative errno. + */ +int clk_set_ceiling_rate(struct clk *clk, unsigned long rate);
And this called clk_set_min_rate()?
+ +/** * clk_set_parent - set the parent clock source for this clock * @clk: clock source * @parent: parent clock source
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