clkdev: add managed clkdev lookup registration

Clkdev registration lacks of managed registration functions and it
seems few drivers do not drop clkdev lookups at exit. Add
devm_clk_hw_register_clkdev and devm_clk_release_clkdev to ease lookup
releasing at exit.

Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

Documentation/driver-model/devres.txt

@@ -245,6 +245,7 @@ CLOCK
   devm_clk_put()
   devm_clk_hw_register()
   devm_of_clk_add_hw_provider()
+  devm_clk_hw_register_clkdev()
 
 DMA
   dmaenginem_async_device_register()

drivers/clk/clkdev.c

@@ -401,6 +401,23 @@ static struct clk_lookup *__clk_register_clkdev(struct clk_hw *hw,
 	return cl;
 }
 
+static int do_clk_register_clkdev(struct clk_hw *hw,
+	struct clk_lookup **cl, const char *con_id, const char *dev_id)
+{
+	if (IS_ERR(hw))
+		return PTR_ERR(hw);
+	/*
+	 * Since dev_id can be NULL, and NULL is handled specially, we must
+	 * pass it as either a NULL format string, or with "%s".
+	 */
+	if (dev_id)
+		*cl = __clk_register_clkdev(hw, con_id, "%s", dev_id);
+	else
+		*cl = __clk_register_clkdev(hw, con_id, NULL);
+
+	return *cl ? 0 : -ENOMEM;
+}
+
 /**
  * clk_register_clkdev - register one clock lookup for a struct clk
  * @clk: struct clk to associate with all clk_lookups
@@ -423,17 +440,8 @@ int clk_register_clkdev(struct clk *clk, const char *con_id,
 	if (IS_ERR(clk))
 		return PTR_ERR(clk);
 
-	/*
-	 * Since dev_id can be NULL, and NULL is handled specially, we must
-	 * pass it as either a NULL format string, or with "%s".
-	 */
-	if (dev_id)
-		cl = __clk_register_clkdev(__clk_get_hw(clk), con_id, "%s",
-					   dev_id);
-	else
-		cl = __clk_register_clkdev(__clk_get_hw(clk), con_id, NULL);
-
-	return cl ? 0 : -ENOMEM;
+	return do_clk_register_clkdev(__clk_get_hw(clk), &cl, con_id,
+					      dev_id);
 }
 EXPORT_SYMBOL(clk_register_clkdev);
 
@@ -456,18 +464,75 @@ int clk_hw_register_clkdev(struct clk_hw *hw, const char *con_id,
 {
 	struct clk_lookup *cl;
 
-	if (IS_ERR(hw))
-		return PTR_ERR(hw);
-
-	/*
-	 * Since dev_id can be NULL, and NULL is handled specially, we must
-	 * pass it as either a NULL format string, or with "%s".
-	 */
-	if (dev_id)
-		cl = __clk_register_clkdev(hw, con_id, "%s", dev_id);
-	else
-		cl = __clk_register_clkdev(hw, con_id, NULL);
-
-	return cl ? 0 : -ENOMEM;
+	return do_clk_register_clkdev(hw, &cl, con_id, dev_id);
 }
 EXPORT_SYMBOL(clk_hw_register_clkdev);
+
+static void devm_clkdev_release(struct device *dev, void *res)
+{
+	clkdev_drop(*(struct clk_lookup **)res);
+}
+
+static int devm_clk_match_clkdev(struct device *dev, void *res, void *data)
+{
+	struct clk_lookup **l = res;
+
+	return *l == data;
+}
+
+/**
+ * devm_clk_release_clkdev - Resource managed clkdev lookup release
+ * @dev: device this lookup is bound
+ * @con_id: connection ID string on device
+ * @dev_id: format string describing device name
+ *
+ * Drop the clkdev lookup created with devm_clk_hw_register_clkdev.
+ * Normally this function will not need to be called and the resource
+ * management code will ensure that the resource is freed.
+ */
+void devm_clk_release_clkdev(struct device *dev, const char *con_id,
+			     const char *dev_id)
+{
+	struct clk_lookup *cl;
+	int rval;
+
+	cl = clk_find(dev_id, con_id);
+	WARN_ON(!cl);
+	rval = devres_release(dev, devm_clkdev_release,
+			      devm_clk_match_clkdev, cl);
+	WARN_ON(rval);
+}
+EXPORT_SYMBOL(devm_clk_release_clkdev);
+
+/**
+ * devm_clk_hw_register_clkdev - managed clk lookup registration for clk_hw
+ * @dev: device this lookup is bound
+ * @hw: struct clk_hw to associate with all clk_lookups
+ * @con_id: connection ID string on device
+ * @dev_id: format string describing device name
+ *
+ * con_id or dev_id may be NULL as a wildcard, just as in the rest of
+ * clkdev.
+ *
+ * To make things easier for mass registration, we detect error clk_hws
+ * from a previous clk_hw_register_*() call, and return the error code for
+ * those.  This is to permit this function to be called immediately
+ * after clk_hw_register_*().
+ */
+int devm_clk_hw_register_clkdev(struct device *dev, struct clk_hw *hw,
+				const char *con_id, const char *dev_id)
+{
+	int rval = -ENOMEM;
+	struct clk_lookup **cl;
+
+	cl = devres_alloc(devm_clkdev_release, sizeof(*cl), GFP_KERNEL);
+	if (cl) {
+		rval = do_clk_register_clkdev(hw, cl, con_id, dev_id);
+		if (!rval)
+			devres_add(dev, cl);
+		else
+			devres_free(cl);
+	}
+	return rval;
+}
+EXPORT_SYMBOL(devm_clk_hw_register_clkdev);

include/linux/clkdev.h

@@ -52,4 +52,8 @@ int clk_add_alias(const char *, const char *, const char *, struct device *);
 int clk_register_clkdev(struct clk *, const char *, const char *);
 int clk_hw_register_clkdev(struct clk_hw *, const char *, const char *);
 
+int devm_clk_hw_register_clkdev(struct device *dev, struct clk_hw *hw,
+				const char *con_id, const char *dev_id);
+void devm_clk_release_clkdev(struct device *dev, const char *con_id,
+			     const char *dev_id);
 #endif