clk: Add rate constraints to clocks

Adds a way for clock consumers to set maximum and minimum rates. This
can be used for thermal drivers to set minimum rates, or by misc.
drivers to set maximum rates to assure a minimum performance level.

Changes the signature of the determine_rate callback by adding the
parameters min_rate and max_rate.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
[sboyd@codeaurora.org: set req_rate in __clk_init]
Signed-off-by: Michael Turquette <mturquette@linaro.org>
[mturquette@linaro.org: min/max rate for sun6i_ahb1_clk_determine_rate
                        migrated clk-private.h changes to clk.c]

1 files changed, 218 insertions, 54 deletions

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index cdc1fa58e4f1..113456030d66 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -42,8 +42,6 @@ static unsigned long clk_core_get_rate(struct clk_core *clk);
 static int clk_core_get_phase(struct clk_core *clk);
 static bool clk_core_is_prepared(struct clk_core *clk);
 static bool clk_core_is_enabled(struct clk_core *clk);
-static unsigned long clk_core_round_rate_nolock(struct clk_core *clk,
-						unsigned long rate);
 static struct clk_core *clk_core_lookup(const char *name);
 
 /***    private data structures    ***/
@@ -59,6 +57,7 @@ struct clk_core {
 	u8			num_parents;
 	u8			new_parent_index;
 	unsigned long		rate;
+	unsigned long		req_rate;
 	unsigned long		new_rate;
 	struct clk_core		*new_parent;
 	struct clk_core		*new_child;
@@ -70,6 +69,7 @@ struct clk_core {
 	struct hlist_head	children;
 	struct hlist_node	child_node;
 	struct hlist_node	debug_node;
+	struct hlist_head	clks;
 	unsigned int		notifier_count;
 #ifdef CONFIG_DEBUG_FS
 	struct dentry		*dentry;
@@ -81,6 +81,9 @@ struct clk {
 	struct clk_core	*core;
 	const char *dev_id;
 	const char *con_id;
+	unsigned long min_rate;
+	unsigned long max_rate;
+	struct hlist_node child_node;
 };
 
 /***           locking             ***/
@@ -783,6 +786,8 @@ static bool mux_is_better_rate(unsigned long rate, unsigned long now,
 
 static long
 clk_mux_determine_rate_flags(struct clk_hw *hw, unsigned long rate,
+			     unsigned long min_rate,
+			     unsigned long max_rate,
 			     unsigned long *best_parent_rate,
 			     struct clk_hw **best_parent_p,
 			     unsigned long flags)
@@ -795,7 +800,8 @@ clk_mux_determine_rate_flags(struct clk_hw *hw, unsigned long rate,
 	if (core->flags & CLK_SET_RATE_NO_REPARENT) {
 		parent = core->parent;
 		if (core->flags & CLK_SET_RATE_PARENT)
-			best = clk_core_round_rate_nolock(parent, rate);
+			best = __clk_determine_rate(parent->hw, rate,
+						    min_rate, max_rate);
 		else if (parent)
 			best = clk_core_get_rate_nolock(parent);
 		else
@@ -810,7 +816,9 @@ clk_mux_determine_rate_flags(struct clk_hw *hw, unsigned long rate,
 		if (!parent)
 			continue;
 		if (core->flags & CLK_SET_RATE_PARENT)
-			parent_rate = clk_core_round_rate_nolock(parent, rate);
+			parent_rate = __clk_determine_rate(parent->hw, rate,
+							   min_rate,
+							   max_rate);
 		else
 			parent_rate = clk_core_get_rate_nolock(parent);
 		if (mux_is_better_rate(rate, parent_rate, best, flags)) {
@@ -834,25 +842,47 @@ struct clk *__clk_lookup(const char *name)
 	return !core ? NULL : core->hw->clk;
 }
 
+static void clk_core_get_boundaries(struct clk_core *clk,
+				    unsigned long *min_rate,
+				    unsigned long *max_rate)
+{
+	struct clk *clk_user;
+
+	*min_rate = 0;
+	*max_rate = ULONG_MAX;
+
+	hlist_for_each_entry(clk_user, &clk->clks, child_node)
+		*min_rate = max(*min_rate, clk_user->min_rate);
+
+	hlist_for_each_entry(clk_user, &clk->clks, child_node)
+		*max_rate = min(*max_rate, clk_user->max_rate);
+}
+
 /*
  * 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 min_rate,
+			      unsigned long max_rate,
 			      unsigned long *best_parent_rate,
 			      struct clk_hw **best_parent_p)
 {
-	return clk_mux_determine_rate_flags(hw, rate, best_parent_rate,
+	return clk_mux_determine_rate_flags(hw, rate, min_rate, max_rate,
+					    best_parent_rate,
 					    best_parent_p, 0);
 }
 EXPORT_SYMBOL_GPL(__clk_mux_determine_rate);
 
 long __clk_mux_determine_rate_closest(struct clk_hw *hw, unsigned long rate,
+			      unsigned long min_rate,
+			      unsigned long max_rate,
 			      unsigned long *best_parent_rate,
 			      struct clk_hw **best_parent_p)
 {
-	return clk_mux_determine_rate_flags(hw, rate, best_parent_rate,
+	return clk_mux_determine_rate_flags(hw, rate, min_rate, max_rate,
+					    best_parent_rate,
 					    best_parent_p,
 					    CLK_MUX_ROUND_CLOSEST);
 }
@@ -1068,7 +1098,9 @@ int clk_enable(struct clk *clk)
 EXPORT_SYMBOL_GPL(clk_enable);
 
 static unsigned long clk_core_round_rate_nolock(struct clk_core *clk,
-						unsigned long rate)
+						unsigned long rate,
+						unsigned long min_rate,
+						unsigned long max_rate)
 {
 	unsigned long parent_rate = 0;
 	struct clk_core *parent;
@@ -1083,17 +1115,41 @@ 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,
+						min_rate, max_rate,
+						&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)
-		return clk_core_round_rate_nolock(clk->parent, rate);
+		return clk_core_round_rate_nolock(clk->parent, rate, min_rate,
+						  max_rate);
 	else
 		return clk->rate;
 }
 
 /**
+ * __clk_determine_rate - get the closest rate actually supported by a clock
+ * @hw: determine the rate of this clock
+ * @rate: target rate
+ * @min_rate: returned rate must be greater than this rate
+ * @max_rate: returned rate must be less than this rate
+ *
+ * Caller must hold prepare_lock.  Useful for clk_ops such as .set_rate and
+ * .determine_rate.
+ */
+unsigned long __clk_determine_rate(struct clk_hw *hw,
+				   unsigned long rate,
+				   unsigned long min_rate,
+				   unsigned long max_rate)
+{
+	if (!hw)
+		return 0;
+
+	return clk_core_round_rate_nolock(hw->core, rate, min_rate, max_rate);
+}
+EXPORT_SYMBOL_GPL(__clk_determine_rate);
+
+/**
  * __clk_round_rate - round the given rate for a clk
  * @clk: round the rate of this clock
  * @rate: the rate which is to be rounded
@@ -1102,10 +1158,15 @@ static unsigned long clk_core_round_rate_nolock(struct clk_core *clk,
  */
 unsigned long __clk_round_rate(struct clk *clk, unsigned long rate)
 {
+	unsigned long min_rate;
+	unsigned long max_rate;
+
 	if (!clk)
 		return 0;
 
-	return clk_core_round_rate_nolock(clk->core, rate);
+	clk_core_get_boundaries(clk->core, &min_rate, &max_rate);
+
+	return clk_core_round_rate_nolock(clk->core, rate, min_rate, max_rate);
 }
 EXPORT_SYMBOL_GPL(__clk_round_rate);
 
@@ -1126,7 +1187,7 @@ long clk_round_rate(struct clk *clk, unsigned long rate)
 		return 0;
 
 	clk_prepare_lock();
-	ret = clk_core_round_rate_nolock(clk->core, rate);
+	ret = __clk_round_rate(clk, rate);
 	clk_prepare_unlock();
 
 	return ret;
@@ -1517,6 +1578,8 @@ static struct clk_core *clk_calc_new_rates(struct clk_core *clk,
 	struct clk_hw *parent_hw;
 	unsigned long best_parent_rate = 0;
 	unsigned long new_rate;
+	unsigned long min_rate;
+	unsigned long max_rate;
 	int p_index = 0;
 
 	/* sanity */
@@ -1528,16 +1591,22 @@ static struct clk_core *clk_calc_new_rates(struct clk_core *clk,
 	if (parent)
 		best_parent_rate = parent->rate;
 
+	clk_core_get_boundaries(clk, &min_rate, &max_rate);
+
 	/* find the closest rate and parent clk/rate */
 	if (clk->ops->determine_rate) {
 		parent_hw = parent ? parent->hw : NULL;
 		new_rate = clk->ops->determine_rate(clk->hw, rate,
+						    min_rate,
+						    max_rate,
 						    &best_parent_rate,
 						    &parent_hw);
 		parent = parent_hw ? parent_hw->core : NULL;
 	} else if (clk->ops->round_rate) {
 		new_rate = clk->ops->round_rate(clk->hw, rate,
 						&best_parent_rate);
+		if (new_rate < min_rate || new_rate > max_rate)
+			return NULL;
 	} else if (!parent || !(clk->flags & CLK_SET_RATE_PARENT)) {
 		/* pass-through clock without adjustable parent */
 		clk->new_rate = clk->rate;
@@ -1675,6 +1744,45 @@ static void clk_change_rate(struct clk_core *clk)
 		clk_change_rate(clk->new_child);
 }
 
+static int clk_core_set_rate_nolock(struct clk_core *clk,
+				    unsigned long req_rate)
+{
+	struct clk_core *top, *fail_clk;
+	unsigned long rate = req_rate;
+	int ret = 0;
+
+	if (!clk)
+		return 0;
+
+	/* bail early if nothing to do */
+	if (rate == clk_core_get_rate_nolock(clk))
+		return 0;
+
+	if ((clk->flags & CLK_SET_RATE_GATE) && clk->prepare_count)
+		return -EBUSY;
+
+	/* calculate new rates and get the topmost changed clock */
+	top = clk_calc_new_rates(clk, rate);
+	if (!top)
+		return -EINVAL;
+
+	/* notify that we are about to change rates */
+	fail_clk = clk_propagate_rate_change(top, PRE_RATE_CHANGE);
+	if (fail_clk) {
+		pr_debug("%s: failed to set %s rate\n", __func__,
+				fail_clk->name);
+		clk_propagate_rate_change(top, ABORT_RATE_CHANGE);
+		return -EBUSY;
+	}
+
+	/* change the rates */
+	clk_change_rate(top);
+
+	clk->req_rate = req_rate;
+
+	return ret;
+}
+
 /**
  * clk_set_rate - specify a new rate for clk
  * @clk: the clk whose rate is being changed
@@ -1698,8 +1806,7 @@ static void clk_change_rate(struct clk_core *clk)
  */
 int clk_set_rate(struct clk *clk, unsigned long rate)
 {
-	struct clk_core *top, *fail_clk;
-	int ret = 0;
+	int ret;
 
 	if (!clk)
 		return 0;
@@ -1707,42 +1814,81 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
 	/* prevent racing with updates to the clock topology */
 	clk_prepare_lock();
 
-	/* bail early if nothing to do */
-	if (rate == clk_get_rate(clk))
-		goto out;
+	ret = clk_core_set_rate_nolock(clk->core, rate);
 
-	if ((clk->core->flags & CLK_SET_RATE_GATE) &&
-	    clk->core->prepare_count) {
-		ret = -EBUSY;
-		goto out;
-	}
+	clk_prepare_unlock();
 
-	/* calculate new rates and get the topmost changed clock */
-	top = clk_calc_new_rates(clk->core, rate);
-	if (!top) {
-		ret = -EINVAL;
-		goto out;
-	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(clk_set_rate);
 
-	/* notify that we are about to change rates */
-	fail_clk = clk_propagate_rate_change(top, PRE_RATE_CHANGE);
-	if (fail_clk) {
-		pr_debug("%s: failed to set %s rate\n", __func__,
-				fail_clk->name);
-		clk_propagate_rate_change(top, ABORT_RATE_CHANGE);
-		ret = -EBUSY;
-		goto out;
+/**
+ * clk_set_rate_range - set a rate range for a clock source
+ * @clk: clock source
+ * @min: desired minimum clock rate in Hz, inclusive
+ * @max: desired maximum clock rate in Hz, inclusive
+ *
+ * Returns success (0) or negative errno.
+ */
+int clk_set_rate_range(struct clk *clk, unsigned long min, unsigned long max)
+{
+	int ret = 0;
+
+	if (!clk)
+		return 0;
+
+	if (min > max) {
+		pr_err("%s: clk %s dev %s con %s: invalid range [%lu, %lu]\n",
+		       __func__, clk->core->name, clk->dev_id, clk->con_id,
+		       min, max);
+		return -EINVAL;
 	}
 
-	/* change the rates */
-	clk_change_rate(top);
+	clk_prepare_lock();
+
+	if (min != clk->min_rate || max != clk->max_rate) {
+		clk->min_rate = min;
+		clk->max_rate = max;
+		ret = clk_core_set_rate_nolock(clk->core, clk->core->req_rate);
+	}
 
-out:
 	clk_prepare_unlock();
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(clk_set_rate);
+EXPORT_SYMBOL_GPL(clk_set_rate_range);
+
+/**
+ * clk_set_min_rate - set a minimum clock rate for a clock source
+ * @clk: clock source
+ * @rate: desired minimum clock rate in Hz, inclusive
+ *
+ * Returns success (0) or negative errno.
+ */
+int clk_set_min_rate(struct clk *clk, unsigned long rate)
+{
+	if (!clk)
+		return 0;
+
+	return clk_set_rate_range(clk, rate, clk->max_rate);
+}
+EXPORT_SYMBOL_GPL(clk_set_min_rate);
+
+/**
+ * clk_set_max_rate - set a maximum clock rate for a clock source
+ * @clk: clock source
+ * @rate: desired maximum clock rate in Hz, inclusive
+ *
+ * Returns success (0) or negative errno.
+ */
+int clk_set_max_rate(struct clk *clk, unsigned long rate)
+{
+	if (!clk)
+		return 0;
+
+	return clk_set_rate_range(clk, clk->min_rate, rate);
+}
+EXPORT_SYMBOL_GPL(clk_set_max_rate);
 
 /**
  * clk_get_parent - return the parent of a clk
@@ -2038,6 +2184,7 @@ static int __clk_init(struct device *dev, struct clk *clk_user)
 	struct clk_core *orphan;
 	struct hlist_node *tmp2;
 	struct clk_core *clk;
+	unsigned long rate;
 
 	if (!clk_user)
 		return -EINVAL;
@@ -2162,12 +2309,13 @@ static int __clk_init(struct device *dev, struct clk *clk_user)
 	 * then rate is set to zero.
 	 */
 	if (clk->ops->recalc_rate)
-		clk->rate = clk->ops->recalc_rate(clk->hw,
+		rate = clk->ops->recalc_rate(clk->hw,
 				clk_core_get_rate_nolock(clk->parent));
 	else if (clk->parent)
-		clk->rate = clk->parent->rate;
+		rate = clk->parent->rate;
 	else
-		clk->rate = 0;
+		rate = 0;
+	clk->rate = clk->req_rate = rate;
 
 	/*
 	 * walk the list of orphan clocks and reparent any that are children of
@@ -2225,10 +2373,24 @@ struct clk *__clk_create_clk(struct clk_hw *hw, const char *dev_id,
 	clk->core = hw->core;
 	clk->dev_id = dev_id;
 	clk->con_id = con_id;
+	clk->max_rate = ULONG_MAX;
+
+	clk_prepare_lock();
+	hlist_add_head(&clk->child_node, &hw->core->clks);
+	clk_prepare_unlock();
 
 	return clk;
 }
 
+static void __clk_free_clk(struct clk *clk)
+{
+	clk_prepare_lock();
+	hlist_del(&clk->child_node);
+	clk_prepare_unlock();
+
+	kfree(clk);
+}
+
 /**
  * clk_register - allocate a new clock, register it and return an opaque cookie
  * @dev: device that is registering this clock
@@ -2288,6 +2450,8 @@ struct clk *clk_register(struct device *dev, struct clk_hw *hw)
 		}
 	}
 
+	INIT_HLIST_HEAD(&clk->clks);
+
 	hw->clk = __clk_create_clk(hw, NULL, NULL);
 	if (IS_ERR(hw->clk)) {
 		pr_err("%s: could not allocate per-user clk\n", __func__);
@@ -2299,8 +2463,9 @@ struct clk *clk_register(struct device *dev, struct clk_hw *hw)
 	if (!ret)
 		return hw->clk;
 
-	kfree(hw->clk);
+	__clk_free_clk(hw->clk);
 	hw->clk = NULL;
+
 fail_parent_names_copy:
 	while (--i >= 0)
 		kfree(clk->parent_names[i]);
@@ -2489,25 +2654,24 @@ int __clk_get(struct clk *clk)
 	return 1;
 }
 
-static void clk_core_put(struct clk_core *core)
+void __clk_put(struct clk *clk)
 {
 	struct module *owner;
 
-	owner = core->owner;
+	if (!clk || WARN_ON_ONCE(IS_ERR(clk)))
+		return;
 
 	clk_prepare_lock();
-	kref_put(&core->ref, __clk_release);
+
+	hlist_del(&clk->child_node);
+	clk_core_set_rate_nolock(clk->core, clk->core->req_rate);
+	owner = clk->core->owner;
+	kref_put(&clk->core->ref, __clk_release);
+
 	clk_prepare_unlock();
 
 	module_put(owner);
-}
-
-void __clk_put(struct clk *clk)
-{
-	if (!clk || WARN_ON_ONCE(IS_ERR(clk)))
-		return;
 
-	clk_core_put(clk->core);
 	kfree(clk);
 }