1 files changed, 301 insertions, 105 deletions

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index ed87b2405806..934cfd18f72d 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -19,14 +19,77 @@
 #include <linux/of.h>
 #include <linux/device.h>
 #include <linux/init.h>
+#include <linux/sched.h>
 
 static DEFINE_SPINLOCK(enable_lock);
 static DEFINE_MUTEX(prepare_lock);
 
+static struct task_struct *prepare_owner;
+static struct task_struct *enable_owner;
+
+static int prepare_refcnt;
+static int enable_refcnt;
+
 static HLIST_HEAD(clk_root_list);
 static HLIST_HEAD(clk_orphan_list);
 static LIST_HEAD(clk_notifier_list);
 
+/***           locking             ***/
+static void clk_prepare_lock(void)
+{
+	if (!mutex_trylock(&prepare_lock)) {
+		if (prepare_owner == current) {
+			prepare_refcnt++;
+			return;
+		}
+		mutex_lock(&prepare_lock);
+	}
+	WARN_ON_ONCE(prepare_owner != NULL);
+	WARN_ON_ONCE(prepare_refcnt != 0);
+	prepare_owner = current;
+	prepare_refcnt = 1;
+}
+
+static void clk_prepare_unlock(void)
+{
+	WARN_ON_ONCE(prepare_owner != current);
+	WARN_ON_ONCE(prepare_refcnt == 0);
+
+	if (--prepare_refcnt)
+		return;
+	prepare_owner = NULL;
+	mutex_unlock(&prepare_lock);
+}
+
+static unsigned long clk_enable_lock(void)
+{
+	unsigned long flags;
+
+	if (!spin_trylock_irqsave(&enable_lock, flags)) {
+		if (enable_owner == current) {
+			enable_refcnt++;
+			return flags;
+		}
+		spin_lock_irqsave(&enable_lock, flags);
+	}
+	WARN_ON_ONCE(enable_owner != NULL);
+	WARN_ON_ONCE(enable_refcnt != 0);
+	enable_owner = current;
+	enable_refcnt = 1;
+	return flags;
+}
+
+static void clk_enable_unlock(unsigned long flags)
+{
+	WARN_ON_ONCE(enable_owner != current);
+	WARN_ON_ONCE(enable_refcnt == 0);
+
+	if (--enable_refcnt)
+		return;
+	enable_owner = NULL;
+	spin_unlock_irqrestore(&enable_lock, flags);
+}
+
 /***        debugfs support        ***/
 
 #ifdef CONFIG_COMMON_CLK_DEBUG
@@ -69,7 +132,7 @@ static int clk_summary_show(struct seq_file *s, void *data)
 	seq_printf(s, "   clock                        enable_cnt  prepare_cnt  rate\n");
 	seq_printf(s, "---------------------------------------------------------------------\n");
 
-	mutex_lock(&prepare_lock);
+	clk_prepare_lock();
 
 	hlist_for_each_entry(c, &clk_root_list, child_node)
 		clk_summary_show_subtree(s, c, 0);
@@ -77,7 +140,7 @@ static int clk_summary_show(struct seq_file *s, void *data)
 	hlist_for_each_entry(c, &clk_orphan_list, child_node)
 		clk_summary_show_subtree(s, c, 0);
 
-	mutex_unlock(&prepare_lock);
+	clk_prepare_unlock();
 
 	return 0;
 }
@@ -130,7 +193,7 @@ static int clk_dump(struct seq_file *s, void *data)
 
 	seq_printf(s, "{");
 
-	mutex_lock(&prepare_lock);
+	clk_prepare_lock();
 
 	hlist_for_each_entry(c, &clk_root_list, child_node) {
 		if (!first_node)
@@ -144,7 +207,7 @@ static int clk_dump(struct seq_file *s, void *data)
 		clk_dump_subtree(s, c, 0);
 	}
 
-	mutex_unlock(&prepare_lock);
+	clk_prepare_unlock();
 
 	seq_printf(s, "}");
 	return 0;
@@ -280,6 +343,39 @@ out:
 }
 
 /**
+ * clk_debug_reparent - reparent clk node in the debugfs clk tree
+ * @clk: the clk being reparented
+ * @new_parent: the new clk parent, may be NULL
+ *
+ * Rename clk entry in the debugfs clk tree if debugfs has been
+ * initialized.  Otherwise it bails out early since the debugfs clk tree
+ * will be created lazily by clk_debug_init as part of a late_initcall.
+ *
+ * Caller must hold prepare_lock.
+ */
+static void clk_debug_reparent(struct clk *clk, struct clk *new_parent)
+{
+	struct dentry *d;
+	struct dentry *new_parent_d;
+
+	if (!inited)
+		return;
+
+	if (new_parent)
+		new_parent_d = new_parent->dentry;
+	else
+		new_parent_d = orphandir;
+
+	d = debugfs_rename(clk->dentry->d_parent, clk->dentry,
+			new_parent_d, clk->name);
+	if (d)
+		clk->dentry = d;
+	else
+		pr_debug("%s: failed to rename debugfs entry for %s\n",
+				__func__, clk->name);
+}
+
+/**
  * clk_debug_init - lazily create the debugfs clk tree visualization
  *
  * clks are often initialized very early during boot before memory can
@@ -316,7 +412,7 @@ static int __init clk_debug_init(void)
 	if (!orphandir)
 		return -ENOMEM;
 
-	mutex_lock(&prepare_lock);
+	clk_prepare_lock();
 
 	hlist_for_each_entry(clk, &clk_root_list, child_node)
 		clk_debug_create_subtree(clk, rootdir);
@@ -326,16 +422,45 @@ static int __init clk_debug_init(void)
 
 	inited = 1;
 
-	mutex_unlock(&prepare_lock);
+	clk_prepare_unlock();
 
 	return 0;
 }
 late_initcall(clk_debug_init);
 #else
 static inline int clk_debug_register(struct clk *clk) { return 0; }
+static inline void clk_debug_reparent(struct clk *clk, struct clk *new_parent)
+{
+}
 #endif
 
 /* caller must hold prepare_lock */
+static void clk_unprepare_unused_subtree(struct clk *clk)
+{
+	struct clk *child;
+
+	if (!clk)
+		return;
+
+	hlist_for_each_entry(child, &clk->children, child_node)
+		clk_unprepare_unused_subtree(child);
+
+	if (clk->prepare_count)
+		return;
+
+	if (clk->flags & CLK_IGNORE_UNUSED)
+		return;
+
+	if (__clk_is_prepared(clk)) {
+		if (clk->ops->unprepare_unused)
+			clk->ops->unprepare_unused(clk->hw);
+		else if (clk->ops->unprepare)
+			clk->ops->unprepare(clk->hw);
+	}
+}
+EXPORT_SYMBOL_GPL(__clk_get_flags);
+
+/* caller must hold prepare_lock */
 static void clk_disable_unused_subtree(struct clk *clk)
 {
 	struct clk *child;
@@ -347,7 +472,7 @@ static void clk_disable_unused_subtree(struct clk *clk)
 	hlist_for_each_entry(child, &clk->children, child_node)
 		clk_disable_unused_subtree(child);
 
-	spin_lock_irqsave(&enable_lock, flags);
+	flags = clk_enable_lock();
 
 	if (clk->enable_count)
 		goto unlock_out;
@@ -368,17 +493,30 @@ static void clk_disable_unused_subtree(struct clk *clk)
 	}
 
 unlock_out:
-	spin_unlock_irqrestore(&enable_lock, flags);
+	clk_enable_unlock(flags);
 
 out:
 	return;
 }
 
+static bool clk_ignore_unused;
+static int __init clk_ignore_unused_setup(char *__unused)
+{
+	clk_ignore_unused = true;
+	return 1;
+}
+__setup("clk_ignore_unused", clk_ignore_unused_setup);
+
 static int clk_disable_unused(void)
 {
 	struct clk *clk;
 
-	mutex_lock(&prepare_lock);
+	if (clk_ignore_unused) {
+		pr_warn("clk: Not disabling unused clocks\n");
+		return 0;
+	}
+
+	clk_prepare_lock();
 
 	hlist_for_each_entry(clk, &clk_root_list, child_node)
 		clk_disable_unused_subtree(clk);
@@ -386,7 +524,13 @@ static int clk_disable_unused(void)
 	hlist_for_each_entry(clk, &clk_orphan_list, child_node)
 		clk_disable_unused_subtree(clk);
 
-	mutex_unlock(&prepare_lock);
+	hlist_for_each_entry(clk, &clk_root_list, child_node)
+		clk_unprepare_unused_subtree(clk);
+
+	hlist_for_each_entry(clk, &clk_orphan_list, child_node)
+		clk_unprepare_unused_subtree(clk);
+
+	clk_prepare_unlock();
 
 	return 0;
 }
@@ -451,6 +595,27 @@ unsigned long __clk_get_flags(struct clk *clk)
 	return !clk ? 0 : clk->flags;
 }
 
+bool __clk_is_prepared(struct clk *clk)
+{
+	int ret;
+
+	if (!clk)
+		return false;
+
+	/*
+	 * .is_prepared is optional for clocks that can prepare
+	 * fall back to software usage counter if it is missing
+	 */
+	if (!clk->ops->is_prepared) {
+		ret = clk->prepare_count ? 1 : 0;
+		goto out;
+	}
+
+	ret = clk->ops->is_prepared(clk->hw);
+out:
+	return !!ret;
+}
+
 bool __clk_is_enabled(struct clk *clk)
 {
 	int ret;
@@ -548,9 +713,9 @@ void __clk_unprepare(struct clk *clk)
  */
 void clk_unprepare(struct clk *clk)
 {
-	mutex_lock(&prepare_lock);
+	clk_prepare_lock();
 	__clk_unprepare(clk);
-	mutex_unlock(&prepare_lock);
+	clk_prepare_unlock();
 }
 EXPORT_SYMBOL_GPL(clk_unprepare);
 
@@ -596,9 +761,9 @@ int clk_prepare(struct clk *clk)
 {
 	int ret;
 
-	mutex_lock(&prepare_lock);
+	clk_prepare_lock();
 	ret = __clk_prepare(clk);
-	mutex_unlock(&prepare_lock);
+	clk_prepare_unlock();
 
 	return ret;
 }
@@ -640,9 +805,9 @@ void clk_disable(struct clk *clk)
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&enable_lock, flags);
+	flags = clk_enable_lock();
 	__clk_disable(clk);
-	spin_unlock_irqrestore(&enable_lock, flags);
+	clk_enable_unlock(flags);
 }
 EXPORT_SYMBOL_GPL(clk_disable);
 
@@ -693,9 +858,9 @@ int clk_enable(struct clk *clk)
 	unsigned long flags;
 	int ret;
 
-	spin_lock_irqsave(&enable_lock, flags);
+	flags = clk_enable_lock();
 	ret = __clk_enable(clk);
-	spin_unlock_irqrestore(&enable_lock, flags);
+	clk_enable_unlock(flags);
 
 	return ret;
 }
@@ -740,9 +905,9 @@ long clk_round_rate(struct clk *clk, unsigned long rate)
 {
 	unsigned long ret;
 
-	mutex_lock(&prepare_lock);
+	clk_prepare_lock();
 	ret = __clk_round_rate(clk, rate);
-	mutex_unlock(&prepare_lock);
+	clk_prepare_unlock();
 
 	return ret;
 }
@@ -837,13 +1002,13 @@ unsigned long clk_get_rate(struct clk *clk)
 {
 	unsigned long rate;
 
-	mutex_lock(&prepare_lock);
+	clk_prepare_lock();
 
 	if (clk && (clk->flags & CLK_GET_RATE_NOCACHE))
 		__clk_recalc_rates(clk, 0);
 
 	rate = __clk_get_rate(clk);
-	mutex_unlock(&prepare_lock);
+	clk_prepare_unlock();
 
 	return rate;
 }
@@ -876,16 +1041,16 @@ static int __clk_speculate_rates(struct clk *clk, unsigned long parent_rate)
 	else
 		new_rate = parent_rate;
 
-	/* abort the rate change if a driver returns NOTIFY_BAD */
+	/* abort rate change if a driver returns NOTIFY_BAD or NOTIFY_STOP */
 	if (clk->notifier_count)
 		ret = __clk_notify(clk, PRE_RATE_CHANGE, clk->rate, new_rate);
 
-	if (ret == NOTIFY_BAD)
+	if (ret & NOTIFY_STOP_MASK)
 		goto out;
 
 	hlist_for_each_entry(child, &clk->children, child_node) {
 		ret = __clk_speculate_rates(child, new_rate);
-		if (ret == NOTIFY_BAD)
+		if (ret & NOTIFY_STOP_MASK)
 			break;
 	}
 
@@ -974,11 +1139,11 @@ static struct clk *clk_propagate_rate_change(struct clk *clk, unsigned long even
 	int ret = NOTIFY_DONE;
 
 	if (clk->rate == clk->new_rate)
-		return 0;
+		return NULL;
 
 	if (clk->notifier_count) {
 		ret = __clk_notify(clk, event, clk->rate, clk->new_rate);
-		if (ret == NOTIFY_BAD)
+		if (ret & NOTIFY_STOP_MASK)
 			fail_clk = clk;
 	}
 
@@ -1048,7 +1213,7 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
 	int ret = 0;
 
 	/* prevent racing with updates to the clock topology */
-	mutex_lock(&prepare_lock);
+	clk_prepare_lock();
 
 	/* bail early if nothing to do */
 	if (rate == clk->rate)
@@ -1080,7 +1245,7 @@ int clk_set_rate(struct clk *clk, unsigned long rate)
 	clk_change_rate(top);
 
 out:
-	mutex_unlock(&prepare_lock);
+	clk_prepare_unlock();
 
 	return ret;
 }
@@ -1096,9 +1261,9 @@ struct clk *clk_get_parent(struct clk *clk)
 {
 	struct clk *parent;
 
-	mutex_lock(&prepare_lock);
+	clk_prepare_lock();
 	parent = __clk_get_parent(clk);
-	mutex_unlock(&prepare_lock);
+	clk_prepare_unlock();
 
 	return parent;
 }
@@ -1162,16 +1327,8 @@ out:
 	return ret;
 }
 
-void __clk_reparent(struct clk *clk, struct clk *new_parent)
+static void clk_reparent(struct clk *clk, struct clk *new_parent)
 {
-#ifdef CONFIG_COMMON_CLK_DEBUG
-	struct dentry *d;
-	struct dentry *new_parent_d;
-#endif
-
-	if (!clk || !new_parent)
-		return;
-
 	hlist_del(&clk->child_node);
 
 	if (new_parent)
@@ -1179,39 +1336,20 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent)
 	else
 		hlist_add_head(&clk->child_node, &clk_orphan_list);
 
-#ifdef CONFIG_COMMON_CLK_DEBUG
-	if (!inited)
-		goto out;
-
-	if (new_parent)
-		new_parent_d = new_parent->dentry;
-	else
-		new_parent_d = orphandir;
-
-	d = debugfs_rename(clk->dentry->d_parent, clk->dentry,
-			new_parent_d, clk->name);
-	if (d)
-		clk->dentry = d;
-	else
-		pr_debug("%s: failed to rename debugfs entry for %s\n",
-				__func__, clk->name);
-out:
-#endif
-
 	clk->parent = new_parent;
+}
 
+void __clk_reparent(struct clk *clk, struct clk *new_parent)
+{
+	clk_reparent(clk, new_parent);
+	clk_debug_reparent(clk, new_parent);
 	__clk_recalc_rates(clk, POST_RATE_CHANGE);
 }
 
-static int __clk_set_parent(struct clk *clk, struct clk *parent)
+static u8 clk_fetch_parent_index(struct clk *clk, struct clk *parent)
 {
-	struct clk *old_parent;
-	unsigned long flags;
-	int ret = -EINVAL;
 	u8 i;
 
-	old_parent = clk->parent;
-
 	if (!clk->parents)
 		clk->parents = kzalloc((sizeof(struct clk*) * clk->num_parents),
 								GFP_KERNEL);
@@ -1231,36 +1369,79 @@ static int __clk_set_parent(struct clk *clk, struct clk *parent)
 		}
 	}
 
-	if (i == clk->num_parents) {
-		pr_debug("%s: clock %s is not a possible parent of clock %s\n",
-				__func__, parent->name, clk->name);
-		goto out;
-	}
+	return i;
+}
 
-	/* migrate prepare and enable */
+static int __clk_set_parent(struct clk *clk, struct clk *parent, u8 p_index)
+{
+	unsigned long flags;
+	int ret = 0;
+	struct clk *old_parent = clk->parent;
+	bool migrated_enable = false;
+
+	/* migrate prepare */
 	if (clk->prepare_count)
 		__clk_prepare(parent);
 
-	/* FIXME replace with clk_is_enabled(clk) someday */
-	spin_lock_irqsave(&enable_lock, flags);
-	if (clk->enable_count)
+	flags = clk_enable_lock();
+
+	/* migrate enable */
+	if (clk->enable_count) {
 		__clk_enable(parent);
-	spin_unlock_irqrestore(&enable_lock, flags);
+		migrated_enable = true;
+	}
+
+	/* update the clk tree topology */
+	clk_reparent(clk, parent);
+
+	clk_enable_unlock(flags);
 
 	/* change clock input source */
-	ret = clk->ops->set_parent(clk->hw, i);
+	if (parent && clk->ops->set_parent)
+		ret = clk->ops->set_parent(clk->hw, p_index);
 
-	/* clean up old prepare and enable */
-	spin_lock_irqsave(&enable_lock, flags);
-	if (clk->enable_count)
+	if (ret) {
+		/*
+		 * The error handling is tricky due to that we need to release
+		 * the spinlock while issuing the .set_parent callback. This
+		 * means the new parent might have been enabled/disabled in
+		 * between, which must be considered when doing rollback.
+		 */
+		flags = clk_enable_lock();
+
+		clk_reparent(clk, old_parent);
+
+		if (migrated_enable && clk->enable_count) {
+			__clk_disable(parent);
+		} else if (migrated_enable && (clk->enable_count == 0)) {
+			__clk_disable(old_parent);
+		} else if (!migrated_enable && clk->enable_count) {
+			__clk_disable(parent);
+			__clk_enable(old_parent);
+		}
+
+		clk_enable_unlock(flags);
+
+		if (clk->prepare_count)
+			__clk_unprepare(parent);
+
+		return ret;
+	}
+
+	/* clean up enable for old parent if migration was done */
+	if (migrated_enable) {
+		flags = clk_enable_lock();
 		__clk_disable(old_parent);
-	spin_unlock_irqrestore(&enable_lock, flags);
+		clk_enable_unlock(flags);
+	}
 
+	/* clean up prepare for old parent if migration was done */
 	if (clk->prepare_count)
 		__clk_unprepare(old_parent);
 
-out:
-	return ret;
+	/* update debugfs with new clk tree topology */
+	clk_debug_reparent(clk, parent);
+	return 0;
 }
 
 /**
@@ -1278,44 +1459,59 @@ out:
 int clk_set_parent(struct clk *clk, struct clk *parent)
 {
 	int ret = 0;
+	u8 p_index = 0;
+	unsigned long p_rate = 0;
 
 	if (!clk || !clk->ops)
 		return -EINVAL;
 
-	if (!clk->ops->set_parent)
+	/* verify ops for for multi-parent clks */
+	if ((clk->num_parents > 1) && (!clk->ops->set_parent))
 		return -ENOSYS;
 
 	/* prevent racing with updates to the clock topology */
-	mutex_lock(&prepare_lock);
+	clk_prepare_lock();
 
 	if (clk->parent == parent)
 		goto out;
 
+	/* check that we are allowed to re-parent if the clock is in use */
+	if ((clk->flags & CLK_SET_PARENT_GATE) && clk->prepare_count) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	/* try finding the new parent index */
+	if (parent) {
+		p_index = clk_fetch_parent_index(clk, parent);
+		p_rate = parent->rate;
+		if (p_index == clk->num_parents) {
+			pr_debug("%s: clk %s can not be parent of clk %s\n",
+					__func__, parent->name, clk->name);
+			ret = -EINVAL;
+			goto out;
+		}
+	}
+
 	/* propagate PRE_RATE_CHANGE notifications */
 	if (clk->notifier_count)
-		ret = __clk_speculate_rates(clk, parent->rate);
+		ret = __clk_speculate_rates(clk, p_rate);
 
 	/* abort if a driver objects */
-	if (ret == NOTIFY_STOP)
+	if (ret & NOTIFY_STOP_MASK)
 		goto out;
 
-	/* only re-parent if the clock is not in use */
-	if ((clk->flags & CLK_SET_PARENT_GATE) && clk->prepare_count)
-		ret = -EBUSY;
-	else
-		ret = __clk_set_parent(clk, parent);
+	/* do the re-parent */
+	ret = __clk_set_parent(clk, parent, p_index);
 
-	/* propagate ABORT_RATE_CHANGE if .set_parent failed */
-	if (ret) {
+	/* propagate rate recalculation accordingly */
+	if (ret)
 		__clk_recalc_rates(clk, ABORT_RATE_CHANGE);
-		goto out;
-	}
-
-	/* propagate rate recalculation downstream */
-	__clk_reparent(clk, parent);
+	else
+		__clk_recalc_rates(clk, POST_RATE_CHANGE);
 
 out:
-	mutex_unlock(&prepare_lock);
+	clk_prepare_unlock();
 
 	return ret;
 }
@@ -1338,7 +1534,7 @@ int __clk_init(struct device *dev, struct clk *clk)
 	if (!clk)
 		return -EINVAL;
 
-	mutex_lock(&prepare_lock);
+	clk_prepare_lock();
 
 	/* check to see if a clock with this name is already registered */
 	if (__clk_lookup(clk->name)) {
@@ -1462,7 +1658,7 @@ int __clk_init(struct device *dev, struct clk *clk)
 	clk_debug_register(clk);
 
 out:
-	mutex_unlock(&prepare_lock);
+	clk_prepare_unlock();
 
 	return ret;
 }
@@ -1696,7 +1892,7 @@ int clk_notifier_register(struct clk *clk, struct notifier_block *nb)
 	if (!clk || !nb)
 		return -EINVAL;
 
-	mutex_lock(&prepare_lock);
+	clk_prepare_lock();
 
 	/* search the list of notifiers for this clk */
 	list_for_each_entry(cn, &clk_notifier_list, node)
@@ -1720,7 +1916,7 @@ int clk_notifier_register(struct clk *clk, struct notifier_block *nb)
 	clk->notifier_count++;
 
 out:
-	mutex_unlock(&prepare_lock);
+	clk_prepare_unlock();
 
 	return ret;
 }
@@ -1745,7 +1941,7 @@ int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb)
 	if (!clk || !nb)
 		return -EINVAL;
 
-	mutex_lock(&prepare_lock);
+	clk_prepare_lock();
 
 	list_for_each_entry(cn, &clk_notifier_list, node)
 		if (cn->clk == clk)
@@ -1766,7 +1962,7 @@ int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb)
 		ret = -ENOENT;
 	}
 
-	mutex_unlock(&prepare_lock);
+	clk_prepare_unlock();
 
 	return ret;
 }