1 files changed, 199 insertions, 112 deletions

diff --git a/drivers/base/power/clock_ops.c b/drivers/base/power/clock_ops.c
index 5a42ae4078c2..b69bcb37c830 100644
--- a/drivers/base/power/clock_ops.c
+++ b/drivers/base/power/clock_ops.c
@@ -1,9 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * drivers/base/power/clock_ops.c - Generic clock manipulation PM callbacks
  *
  * Copyright (c) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
- *
- * This file is released under the GPLv2.
  */
 
 #include <linux/kernel.h>
@@ -13,6 +12,7 @@
 #include <linux/pm_clock.h>
 #include <linux/clk.h>
 #include <linux/clkdev.h>
+#include <linux/of_clk.h>
 #include <linux/slab.h>
 #include <linux/err.h>
 #include <linux/pm_domain.h>
@@ -23,6 +23,7 @@
 enum pce_status {
 	PCE_STATUS_NONE = 0,
 	PCE_STATUS_ACQUIRED,
+	PCE_STATUS_PREPARED,
 	PCE_STATUS_ENABLED,
 	PCE_STATUS_ERROR,
 };
@@ -32,10 +33,114 @@ struct pm_clock_entry {
 	char *con_id;
 	struct clk *clk;
 	enum pce_status status;
+	bool enabled_when_prepared;
 };
 
 /**
- * pm_clk_enable - Enable a clock, reporting any errors
+ * pm_clk_list_lock - ensure exclusive access for modifying the PM clock
+ *		      entry list.
+ * @psd: pm_subsys_data instance corresponding to the PM clock entry list
+ *	 and clk_op_might_sleep count to be modified.
+ *
+ * Get exclusive access before modifying the PM clock entry list and the
+ * clock_op_might_sleep count to guard against concurrent modifications.
+ * This also protects against a concurrent clock_op_might_sleep and PM clock
+ * entry list usage in pm_clk_suspend()/pm_clk_resume() that may or may not
+ * happen in atomic context, hence both the mutex and the spinlock must be
+ * taken here.
+ */
+static void pm_clk_list_lock(struct pm_subsys_data *psd)
+	__acquires(&psd->lock)
+{
+	mutex_lock(&psd->clock_mutex);
+	spin_lock_irq(&psd->lock);
+}
+
+/**
+ * pm_clk_list_unlock - counterpart to pm_clk_list_lock().
+ * @psd: the same pm_subsys_data instance previously passed to
+ *	 pm_clk_list_lock().
+ */
+static void pm_clk_list_unlock(struct pm_subsys_data *psd)
+	__releases(&psd->lock)
+{
+	spin_unlock_irq(&psd->lock);
+	mutex_unlock(&psd->clock_mutex);
+}
+
+/**
+ * pm_clk_op_lock - ensure exclusive access for performing clock operations.
+ * @psd: pm_subsys_data instance corresponding to the PM clock entry list
+ *	 and clk_op_might_sleep count being used.
+ * @flags: stored irq flags.
+ * @fn: string for the caller function's name.
+ *
+ * This is used by pm_clk_suspend() and pm_clk_resume() to guard
+ * against concurrent modifications to the clock entry list and the
+ * clock_op_might_sleep count. If clock_op_might_sleep is != 0 then
+ * only the mutex can be locked and those functions can only be used in
+ * non atomic context. If clock_op_might_sleep == 0 then these functions
+ * may be used in any context and only the spinlock can be locked.
+ * Returns -EINVAL if called in atomic context when clock ops might sleep.
+ */
+static int pm_clk_op_lock(struct pm_subsys_data *psd, unsigned long *flags,
+			  const char *fn)
+	/* sparse annotations don't work here as exit state isn't static */
+{
+	bool atomic_context = in_atomic() || irqs_disabled();
+
+try_again:
+	spin_lock_irqsave(&psd->lock, *flags);
+	if (!psd->clock_op_might_sleep) {
+		/* the __release is there to work around sparse limitations */
+		__release(&psd->lock);
+		return 0;
+	}
+
+	/* bail out if in atomic context */
+	if (atomic_context) {
+		pr_err("%s: atomic context with clock_ops_might_sleep = %d",
+		       fn, psd->clock_op_might_sleep);
+		spin_unlock_irqrestore(&psd->lock, *flags);
+		might_sleep();
+		return -EPERM;
+	}
+
+	/* we must switch to the mutex */
+	spin_unlock_irqrestore(&psd->lock, *flags);
+	mutex_lock(&psd->clock_mutex);
+
+	/*
+	 * There was a possibility for psd->clock_op_might_sleep
+	 * to become 0 above. Keep the mutex only if not the case.
+	 */
+	if (likely(psd->clock_op_might_sleep))
+		return 0;
+
+	mutex_unlock(&psd->clock_mutex);
+	goto try_again;
+}
+
+/**
+ * pm_clk_op_unlock - counterpart to pm_clk_op_lock().
+ * @psd: the same pm_subsys_data instance previously passed to
+ *	 pm_clk_op_lock().
+ * @flags: irq flags provided by pm_clk_op_lock().
+ */
+static void pm_clk_op_unlock(struct pm_subsys_data *psd, unsigned long *flags)
+	/* sparse annotations don't work here as entry state isn't static */
+{
+	if (psd->clock_op_might_sleep) {
+		mutex_unlock(&psd->clock_mutex);
+	} else {
+		/* the __acquire is there to work around sparse limitations */
+		__acquire(&psd->lock);
+		spin_unlock_irqrestore(&psd->lock, *flags);
+	}
+}
+
+/**
+ * __pm_clk_enable - Enable a clock, reporting any errors
  * @dev: The device for the given clock
  * @ce: PM clock entry corresponding to the clock.
  */
@@ -43,14 +148,21 @@ static inline void __pm_clk_enable(struct device *dev, struct pm_clock_entry *ce
 {
 	int ret;
 
-	if (ce->status < PCE_STATUS_ERROR) {
+	switch (ce->status) {
+	case PCE_STATUS_ACQUIRED:
+		ret = clk_prepare_enable(ce->clk);
+		break;
+	case PCE_STATUS_PREPARED:
 		ret = clk_enable(ce->clk);
-		if (!ret)
-			ce->status = PCE_STATUS_ENABLED;
-		else
-			dev_err(dev, "%s: failed to enable clk %p, error %d\n",
-				__func__, ce->clk, ret);
+		break;
+	default:
+		return;
 	}
+	if (!ret)
+		ce->status = PCE_STATUS_ENABLED;
+	else
+		dev_err(dev, "%s: failed to enable clk %p, error %d\n",
+			__func__, ce->clk, ret);
 }
 
 /**
@@ -64,12 +176,20 @@ static void pm_clk_acquire(struct device *dev, struct pm_clock_entry *ce)
 		ce->clk = clk_get(dev, ce->con_id);
 	if (IS_ERR(ce->clk)) {
 		ce->status = PCE_STATUS_ERROR;
-	} else {
-		clk_prepare(ce->clk);
+		return;
+	} else if (clk_is_enabled_when_prepared(ce->clk)) {
+		/* we defer preparing the clock in that case */
 		ce->status = PCE_STATUS_ACQUIRED;
-		dev_dbg(dev, "Clock %pC con_id %s managed by runtime PM.\n",
-			ce->clk, ce->con_id);
+		ce->enabled_when_prepared = true;
+	} else if (clk_prepare(ce->clk)) {
+		ce->status = PCE_STATUS_ERROR;
+		dev_err(dev, "clk_prepare() failed\n");
+		return;
+	} else {
+		ce->status = PCE_STATUS_PREPARED;
 	}
+	dev_dbg(dev, "Clock %pC con_id %s managed by runtime PM.\n",
+		ce->clk, ce->con_id);
 }
 
 static int __pm_clk_add(struct device *dev, const char *con_id,
@@ -88,8 +208,6 @@ static int __pm_clk_add(struct device *dev, const char *con_id,
 	if (con_id) {
 		ce->con_id = kstrdup(con_id, GFP_KERNEL);
 		if (!ce->con_id) {
-			dev_err(dev,
-				"Not enough memory for clock connection ID.\n");
 			kfree(ce);
 			return -ENOMEM;
 		}
@@ -103,9 +221,11 @@ static int __pm_clk_add(struct device *dev, const char *con_id,
 
 	pm_clk_acquire(dev, ce);
 
-	spin_lock_irq(&psd->lock);
+	pm_clk_list_lock(psd);
 	list_add_tail(&ce->node, &psd->clock_list);
-	spin_unlock_irq(&psd->lock);
+	if (ce->enabled_when_prepared)
+		psd->clock_op_might_sleep++;
+	pm_clk_list_unlock(psd);
 	return 0;
 }
 
@@ -139,39 +259,6 @@ int pm_clk_add_clk(struct device *dev, struct clk *clk)
 }
 EXPORT_SYMBOL_GPL(pm_clk_add_clk);
 
-
-/**
- * of_pm_clk_add_clk - Start using a device clock for power management.
- * @dev: Device whose clock is going to be used for power management.
- * @name: Name of clock that is going to be used for power management.
- *
- * Add the clock described in the 'clocks' device-tree node that matches
- * with the 'name' provided, to the list of clocks used for the power
- * management of @dev. On success, returns 0. Returns a negative error
- * code if the clock is not found or cannot be added.
- */
-int of_pm_clk_add_clk(struct device *dev, const char *name)
-{
-	struct clk *clk;
-	int ret;
-
-	if (!dev || !dev->of_node || !name)
-		return -EINVAL;
-
-	clk = of_clk_get_by_name(dev->of_node, name);
-	if (IS_ERR(clk))
-		return PTR_ERR(clk);
-
-	ret = pm_clk_add_clk(dev, clk);
-	if (ret) {
-		clk_put(clk);
-		return ret;
-	}
-
-	return 0;
-}
-EXPORT_SYMBOL_GPL(of_pm_clk_add_clk);
-
 /**
  * of_pm_clk_add_clks - Start using device clock(s) for power management.
  * @dev: Device whose clock(s) is going to be used for power management.
@@ -191,8 +278,7 @@ int of_pm_clk_add_clks(struct device *dev)
 	if (!dev || !dev->of_node)
 		return -EINVAL;
 
-	count = of_count_phandle_with_args(dev->of_node, "clocks",
-					   "#clock-cells");
+	count = of_clk_get_parent_count(dev->of_node);
 	if (count <= 0)
 		return -ENODEV;
 
@@ -237,14 +323,20 @@ static void __pm_clk_remove(struct pm_clock_entry *ce)
 	if (!ce)
 		return;
 
-	if (ce->status < PCE_STATUS_ERROR) {
-		if (ce->status == PCE_STATUS_ENABLED)
-			clk_disable(ce->clk);
-
-		if (ce->status >= PCE_STATUS_ACQUIRED) {
-			clk_unprepare(ce->clk);
+	switch (ce->status) {
+	case PCE_STATUS_ENABLED:
+		clk_disable(ce->clk);
+		fallthrough;
+	case PCE_STATUS_PREPARED:
+		clk_unprepare(ce->clk);
+		fallthrough;
+	case PCE_STATUS_ACQUIRED:
+	case PCE_STATUS_ERROR:
+		if (!IS_ERR(ce->clk))
 			clk_put(ce->clk);
-		}
+		break;
+	default:
+		break;
 	}
 
 	kfree(ce->con_id);
@@ -252,44 +344,6 @@ static void __pm_clk_remove(struct pm_clock_entry *ce)
 }
 
 /**
- * pm_clk_remove - Stop using a device clock for power management.
- * @dev: Device whose clock should not be used for PM any more.
- * @con_id: Connection ID of the clock.
- *
- * Remove the clock represented by @con_id from the list of clocks used for
- * the power management of @dev.
- */
-void pm_clk_remove(struct device *dev, const char *con_id)
-{
-	struct pm_subsys_data *psd = dev_to_psd(dev);
-	struct pm_clock_entry *ce;
-
-	if (!psd)
-		return;
-
-	spin_lock_irq(&psd->lock);
-
-	list_for_each_entry(ce, &psd->clock_list, node) {
-		if (!con_id && !ce->con_id)
-			goto remove;
-		else if (!con_id || !ce->con_id)
-			continue;
-		else if (!strcmp(con_id, ce->con_id))
-			goto remove;
-	}
-
-	spin_unlock_irq(&psd->lock);
-	return;
-
- remove:
-	list_del(&ce->node);
-	spin_unlock_irq(&psd->lock);
-
-	__pm_clk_remove(ce);
-}
-EXPORT_SYMBOL_GPL(pm_clk_remove);
-
-/**
  * pm_clk_remove_clk - Stop using a device clock for power management.
  * @dev: Device whose clock should not be used for PM any more.
  * @clk: Clock pointer
@@ -305,19 +359,21 @@ void pm_clk_remove_clk(struct device *dev, struct clk *clk)
 	if (!psd || !clk)
 		return;
 
-	spin_lock_irq(&psd->lock);
+	pm_clk_list_lock(psd);
 
 	list_for_each_entry(ce, &psd->clock_list, node) {
 		if (clk == ce->clk)
 			goto remove;
 	}
 
-	spin_unlock_irq(&psd->lock);
+	pm_clk_list_unlock(psd);
 	return;
 
  remove:
 	list_del(&ce->node);
-	spin_unlock_irq(&psd->lock);
+	if (ce->enabled_when_prepared)
+		psd->clock_op_might_sleep--;
+	pm_clk_list_unlock(psd);
 
 	__pm_clk_remove(ce);
 }
@@ -328,13 +384,16 @@ EXPORT_SYMBOL_GPL(pm_clk_remove_clk);
  * @dev: Device to initialize the list of PM clocks for.
  *
  * Initialize the lock and clock_list members of the device's pm_subsys_data
- * object.
+ * object, set the count of clocks that might sleep to 0.
  */
 void pm_clk_init(struct device *dev)
 {
 	struct pm_subsys_data *psd = dev_to_psd(dev);
-	if (psd)
+	if (psd) {
 		INIT_LIST_HEAD(&psd->clock_list);
+		mutex_init(&psd->clock_mutex);
+		psd->clock_op_might_sleep = 0;
+	}
 }
 EXPORT_SYMBOL_GPL(pm_clk_init);
 
@@ -370,12 +429,13 @@ void pm_clk_destroy(struct device *dev)
 
 	INIT_LIST_HEAD(&list);
 
-	spin_lock_irq(&psd->lock);
+	pm_clk_list_lock(psd);
 
 	list_for_each_entry_safe_reverse(ce, c, &psd->clock_list, node)
 		list_move(&ce->node, &list);
+	psd->clock_op_might_sleep = 0;
 
-	spin_unlock_irq(&psd->lock);
+	pm_clk_list_unlock(psd);
 
 	dev_pm_put_subsys_data(dev);
 
@@ -386,6 +446,23 @@ void pm_clk_destroy(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(pm_clk_destroy);
 
+static void pm_clk_destroy_action(void *data)
+{
+	pm_clk_destroy(data);
+}
+
+int devm_pm_clk_create(struct device *dev)
+{
+	int ret;
+
+	ret = pm_clk_create(dev);
+	if (ret)
+		return ret;
+
+	return devm_add_action_or_reset(dev, pm_clk_destroy_action, dev);
+}
+EXPORT_SYMBOL_GPL(devm_pm_clk_create);
+
 /**
  * pm_clk_suspend - Disable clocks in a device's PM clock list.
  * @dev: Device to disable the clocks for.
@@ -395,23 +472,30 @@ int pm_clk_suspend(struct device *dev)
 	struct pm_subsys_data *psd = dev_to_psd(dev);
 	struct pm_clock_entry *ce;
 	unsigned long flags;
+	int ret;
 
 	dev_dbg(dev, "%s()\n", __func__);
 
 	if (!psd)
 		return 0;
 
-	spin_lock_irqsave(&psd->lock, flags);
+	ret = pm_clk_op_lock(psd, &flags, __func__);
+	if (ret)
+		return ret;
 
 	list_for_each_entry_reverse(ce, &psd->clock_list, node) {
-		if (ce->status < PCE_STATUS_ERROR) {
-			if (ce->status == PCE_STATUS_ENABLED)
+		if (ce->status == PCE_STATUS_ENABLED) {
+			if (ce->enabled_when_prepared) {
+				clk_disable_unprepare(ce->clk);
+				ce->status = PCE_STATUS_ACQUIRED;
+			} else {
 				clk_disable(ce->clk);
-			ce->status = PCE_STATUS_ACQUIRED;
+				ce->status = PCE_STATUS_PREPARED;
+			}
 		}
 	}
 
-	spin_unlock_irqrestore(&psd->lock, flags);
+	pm_clk_op_unlock(psd, &flags);
 
 	return 0;
 }
@@ -426,18 +510,21 @@ int pm_clk_resume(struct device *dev)
 	struct pm_subsys_data *psd = dev_to_psd(dev);
 	struct pm_clock_entry *ce;
 	unsigned long flags;
+	int ret;
 
 	dev_dbg(dev, "%s()\n", __func__);
 
 	if (!psd)
 		return 0;
 
-	spin_lock_irqsave(&psd->lock, flags);
+	ret = pm_clk_op_lock(psd, &flags, __func__);
+	if (ret)
+		return ret;
 
 	list_for_each_entry(ce, &psd->clock_list, node)
 		__pm_clk_enable(dev, ce);
 
-	spin_unlock_irqrestore(&psd->lock, flags);
+	pm_clk_op_unlock(psd, &flags);
 
 	return 0;
 }
@@ -633,7 +720,7 @@ static int pm_clk_notify(struct notifier_block *nb,
  * the remaining members of @clknb should be populated prior to calling this
  * routine.
  */
-void pm_clk_add_notifier(struct bus_type *bus,
+void pm_clk_add_notifier(const struct bus_type *bus,
 				 struct pm_clk_notifier_block *clknb)
 {
 	if (!bus || !clknb)