[PATCH] clkdev: Implement managed clk_get()

[broonie@opensource.wolfsonmicro.com (Mark Brown)]

Allow clk API users to simplify their cleanup paths by providing a
managed version of clk_get() and clk_put().

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
---
 Documentation/driver-model/devres.txt |    3 ++
 drivers/clk/clkdev.c                  |   45 +++++++++++++++++++++++++++++++++
 include/linux/clk.h                   |   32 +++++++++++++++++++++++
 3 files changed, 80 insertions(+), 0 deletions(-)

diff --git a/Documentation/driver-model/devres.txt b/Documentation/driver-model/devres.txt
index 2a596a4..3a10848 100644
--- a/Documentation/driver-model/devres.txt
+++ b/Documentation/driver-model/devres.txt
@@ -276,3 +276,6 @@ REGULATOR
   devm_regulator_get()
   devm_regulator_put()
   devm_regulator_bulk_get()
+
+CLOCK
+  devm_clk_get()
diff --git a/drivers/clk/clkdev.c b/drivers/clk/clkdev.c
index 6db161f..a9a1137 100644
--- a/drivers/clk/clkdev.c
+++ b/drivers/clk/clkdev.c
@@ -89,6 +89,51 @@ void clk_put(struct clk *clk)
 }
 EXPORT_SYMBOL(clk_put);
 
+static void devm_clk_release(struct device *dev, void *res)
+{
+	clk_put(*(struct clk **)res);
+}
+
+struct clk *devm_clk_get(struct device *dev, const char *id)
+{
+	struct clk **ptr, *clk;
+
+	ptr = devres_alloc(devm_clk_release, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return ERR_PTR(-ENOMEM);
+
+	clk = clk_get(dev, id);
+	if (!IS_ERR(clk)) {
+		*ptr = clk;
+		devres_add(dev, ptr);
+	} else {
+		devres_free(ptr);
+	}
+
+	return clk;
+}
+EXPORT_SYMBOL(devm_clk_get);
+
+static int devm_clk_match(struct device *dev, void *res, void *data)
+{
+	struct clk **c = res;
+	if (!c || !*c) {
+		WARN_ON(!c || !*c);
+		return 0;
+	}
+	return *c == data;
+}
+
+void devm_clk_put(struct device *dev, struct clk *clk)
+{
+	int ret;
+
+	ret = devres_destroy(dev, devm_clk_release, devm_clk_match, clk);
+
+	WARN_ON(ret);
+}
+EXPORT_SYMBOL(devm_clk_put);
+
 void clkdev_add(struct clk_lookup *cl)
 {
 	mutex_lock(&clocks_mutex);
diff --git a/include/linux/clk.h b/include/linux/clk.h
index c9547d9..62b0bb0 100644
--- a/include/linux/clk.h
+++ b/include/linux/clk.h
@@ -101,6 +101,26 @@ int clk_notifier_unregister(struct clk *clk, struct notifier_block *nb);
 struct clk *clk_get(struct device *dev, const char *id);
 
 /**
+ * devm_clk_get - lookup and obtain a managed reference to a clock producer.
+ * @dev: device for clock "consumer"
+ * @id: clock comsumer ID
+ *
+ * Returns a struct clk corresponding to the clock producer, or
+ * valid IS_ERR() condition containing errno.  The implementation
+ * uses @dev and @id to determine the clock consumer, and thereby
+ * the clock producer.  (IOW, @id may be identical strings, but
+ * clk_get may return different clock producers depending on @dev.)
+ *
+ * Drivers must assume that the clock source is not enabled.
+ *
+ * devm_clk_get should not be called from within interrupt context.
+ *
+ * The clock will automatically be freed when the device is unbound
+ * from the bus.
+ */
+struct clk *devm_clk_get(struct device *dev, const char *id);
+
+/**
  * clk_prepare - prepare a clock source
  * @clk: clock source
  *
@@ -206,6 +226,18 @@ unsigned long clk_get_rate(struct clk *clk);
  */
 void clk_put(struct clk *clk);
 
+/**
+ * clk_put	- "free" a managed clock source
+ * @dev: device used to acuqire the clock
+ * @clk: clock source acquired with devm_clk_get()
+ *
+ * Note: drivers must ensure that all clk_enable calls made on this
+ * clock source are balanced by clk_disable calls prior to calling
+ * this function.
+ *
+ * clk_put should not be called from within interrupt context.
+ */
+void devm_clk_put(struct device *dev, struct clk *clk);
 
 /*
  * The remaining APIs are optional for machine class support.
-- 
1.7.9.1