clk: Combine __clk_get() and __clk_create_clk()

The __clk_get() function is practically a private clk implementation
detail now. No architecture defines it, and given that new code should
be using the common clk framework there isn't a need for it to keep
existing just to serve clkdev purposes. Let's fold it into the
__clk_create_clk() function and make that a little more generic by
renaming it to clk_hw_create_clk(). This will allow the framework to
create a struct clk handle to a particular clk_hw pointer and link it up
as a consumer wherever that's needed.

Doing this also lets us get rid of the __clk_free_clk() API that had to
be kept in sync with __clk_put(). Splitting that API up into the "link
and unlink from consumer list" phase and "free the clk pointer" phase
allows us to reuse that logic in a couple places, simplifying the code.

Cc: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Jerome Brunet <jbrunet@baylibre.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Jeffrey Hugo <jhugo@codeaurora.org>
Cc: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/clk.c

@@ -3209,42 +3209,103 @@ static int __clk_core_init(struct clk_core *core)
 	return ret;
 }
 
-struct clk *__clk_create_clk(struct clk_hw *hw, const char *dev_id,
+/**
+ * clk_core_link_consumer - Add a clk consumer to the list of consumers in a clk_core
+ * @core: clk to add consumer to
+ * @clk: consumer to link to a clk
+ */
+static void clk_core_link_consumer(struct clk_core *core, struct clk *clk)
+{
+	clk_prepare_lock();
+	hlist_add_head(&clk->clks_node, &core->clks);
+	clk_prepare_unlock();
+}
+
+/**
+ * clk_core_unlink_consumer - Remove a clk consumer from the list of consumers in a clk_core
+ * @clk: consumer to unlink
+ */
+static void clk_core_unlink_consumer(struct clk *clk)
+{
+	lockdep_assert_held(&prepare_lock);
+	hlist_del(&clk->clks_node);
+}
+
+/**
+ * alloc_clk - Allocate a clk consumer, but leave it unlinked to the clk_core
+ * @core: clk to allocate a consumer for
+ * @dev_id: string describing device name
+ * @con_id: connection ID string on device
+ *
+ * Returns: clk consumer left unlinked from the consumer list
+ */
+static struct clk *alloc_clk(struct clk_core *core, const char *dev_id,
 			     const char *con_id)
 {
 	struct clk *clk;
 
-	/* This is to allow this function to be chained to others */
-	if (IS_ERR_OR_NULL(hw))
-		return ERR_CAST(hw);
-
 	clk = kzalloc(sizeof(*clk), GFP_KERNEL);
 	if (!clk)
 		return ERR_PTR(-ENOMEM);
 
-	clk->core = hw->core;
+	clk->core = core;
 	clk->dev_id = dev_id;
 	clk->con_id = kstrdup_const(con_id, GFP_KERNEL);
 	clk->max_rate = ULONG_MAX;
 
-	clk_prepare_lock();
-	hlist_add_head(&clk->clks_node, &hw->core->clks);
-	clk_prepare_unlock();
-
 	return clk;
 }
 
-/* keep in sync with __clk_put */
-void __clk_free_clk(struct clk *clk)
+/**
+ * free_clk - Free a clk consumer
+ * @clk: clk consumer to free
+ *
+ * Note, this assumes the clk has been unlinked from the clk_core consumer
+ * list.
+ */
+static void free_clk(struct clk *clk)
 {
-	clk_prepare_lock();
-	hlist_del(&clk->clks_node);
-	clk_prepare_unlock();
-
 	kfree_const(clk->con_id);
 	kfree(clk);
 }
 
+/**
+ * clk_hw_create_clk: Allocate and link a clk consumer to a clk_core given
+ * a clk_hw
+ * @hw: clk_hw associated with the clk being consumed
+ * @dev_id: string describing device name
+ * @con_id: connection ID string on device
+ *
+ * This is the main function used to create a clk pointer for use by clk
+ * consumers. It connects a consumer to the clk_core and clk_hw structures
+ * used by the framework and clk provider respectively.
+ */
+struct clk *clk_hw_create_clk(struct clk_hw *hw,
+			      const char *dev_id, const char *con_id)
+{
+	struct clk *clk;
+	struct clk_core *core;
+
+	/* This is to allow this function to be chained to others */
+	if (IS_ERR_OR_NULL(hw))
+		return ERR_CAST(hw);
+
+	core = hw->core;
+	clk = alloc_clk(core, dev_id, con_id);
+	if (IS_ERR(clk))
+		return clk;
+
+	if (!try_module_get(core->owner)) {
+		free_clk(clk);
+		return ERR_PTR(-ENOENT);
+	}
+
+	kref_get(&core->ref);
+	clk_core_link_consumer(core, clk);
+
+	return clk;
+}
+
 /**
  * clk_register - allocate a new clock, register it and return an opaque cookie
  * @dev: device that is registering this clock
@@ -3320,17 +3381,27 @@ struct clk *clk_register(struct device *dev, struct clk_hw *hw)
 
 	INIT_HLIST_HEAD(&core->clks);
 
-	hw->clk = __clk_create_clk(hw, NULL, NULL);
+	/*
+	 * Don't call clk_hw_create_clk() here because that would pin the
+	 * provider module to itself and prevent it from ever being removed.
+	 */
+	hw->clk = alloc_clk(core, NULL, NULL);
 	if (IS_ERR(hw->clk)) {
 		ret = PTR_ERR(hw->clk);
 		goto fail_parents;
 	}
 
+	clk_core_link_consumer(hw->core, hw->clk);
+
 	ret = __clk_core_init(core);
 	if (!ret)
 		return hw->clk;
 
-	__clk_free_clk(hw->clk);
+	clk_prepare_lock();
+	clk_core_unlink_consumer(hw->clk);
+	clk_prepare_unlock();
+
+	free_clk(hw->clk);
 	hw->clk = NULL;
 
 fail_parents:
@@ -3601,20 +3672,7 @@ EXPORT_SYMBOL_GPL(devm_clk_hw_unregister);
 /*
  * clkdev helpers
  */
-int __clk_get(struct clk *clk)
-{
-	struct clk_core *core = !clk ? NULL : clk->core;
-
-	if (core) {
-		if (!try_module_get(core->owner))
-			return 0;
-
-		kref_get(&core->ref);
-	}
-	return 1;
-}
 
-/* keep in sync with __clk_free_clk */
 void __clk_put(struct clk *clk)
 {
 	struct module *owner;
@@ -3648,8 +3706,7 @@ void __clk_put(struct clk *clk)
 
 	module_put(owner);
 
-	kfree_const(clk->con_id);
-	kfree(clk);
+	free_clk(clk);
 }
 
 /***        clk rate change notifiers        ***/
@@ -4025,8 +4082,7 @@ struct clk *__of_clk_get_from_provider(struct of_phandle_args *clkspec,
 				       const char *dev_id, const char *con_id)
 {
 	struct of_clk_provider *provider;
-	struct clk *clk = ERR_PTR(-EPROBE_DEFER);
-	struct clk_hw *hw;
+	struct clk_hw *hw = ERR_PTR(-EPROBE_DEFER);
 
 	if (!clkspec)
 		return ERR_PTR(-EINVAL);
@@ -4036,21 +4092,13 @@ struct clk *__of_clk_get_from_provider(struct of_phandle_args *clkspec,
 	list_for_each_entry(provider, &of_clk_providers, link) {
 		if (provider->node == clkspec->np) {
 			hw = __of_clk_get_hw_from_provider(provider, clkspec);
-			clk = __clk_create_clk(hw, dev_id, con_id);
-		}
-
-		if (!IS_ERR(clk)) {
-			if (!__clk_get(clk)) {
-				__clk_free_clk(clk);
-				clk = ERR_PTR(-ENOENT);
-			}
-
-			break;
+			if (!IS_ERR(hw))
+				break;
 		}
 	}
 	mutex_unlock(&of_clk_mutex);
 
-	return clk;
+	return clk_hw_create_clk(hw, dev_id, con_id);
 }
 
 /**

drivers/clk/clk.h

@@ -12,24 +12,20 @@ struct clk *__of_clk_get_from_provider(struct of_phandle_args *clkspec,
 #endif
 
 #ifdef CONFIG_COMMON_CLK
-struct clk *__clk_create_clk(struct clk_hw *hw, const char *dev_id,
-			     const char *con_id);
-void __clk_free_clk(struct clk *clk);
-int __clk_get(struct clk *clk);
+struct clk *clk_hw_create_clk(struct clk_hw *hw,
+			      const char *dev_id, const char *con_id);
 void __clk_put(struct clk *clk);
 #else
 /* All these casts to avoid ifdefs in clkdev... */
 static inline struct clk *
-__clk_create_clk(struct clk_hw *hw, const char *dev_id, const char *con_id)
+clk_hw_create_clk(struct clk_hw *hw, const char *dev_id, const char *con_id)
 {
 	return (struct clk *)hw;
 }
-static inline void __clk_free_clk(struct clk *clk) { }
 static struct clk_hw *__clk_get_hw(struct clk *clk)
 {
 	return (struct clk_hw *)clk;
 }
-static inline int __clk_get(struct clk *clk) { return 1; }
 static inline void __clk_put(struct clk *clk) { }
 
 #endif

drivers/clk/clkdev.c

@@ -174,16 +174,9 @@ struct clk *clk_get_sys(const char *dev_id, const char *con_id)
 	if (!cl)
 		goto out;
 
-	clk = __clk_create_clk(cl->clk_hw, dev_id, con_id);
+	clk = clk_hw_create_clk(cl->clk_hw, dev_id, con_id);
 	if (IS_ERR(clk))
-		goto out;
-
-	if (!__clk_get(clk)) {
-		__clk_free_clk(clk);
 		cl = NULL;
-		goto out;
-	}
-
 out:
 	mutex_unlock(&clocks_mutex);