clk: Add devm_clk_get()

Add a resource managed clk_get() to simplify clock usage in
drivers. This allows driver authors to "get and forget" about
their clocks by automatically calling clk_put() when the driver
is detached. This also encourages clock consumers to use the
clk_get() API correctly by passing in a struct device as an
argument.

Change-Id: I1ed53cd3c26c0390fa30cd3c3dca14bcdd59939f
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
diff --git a/drivers/clk/clkdev.c b/drivers/clk/clkdev.c
index 6db161f..fdff32e 100644
--- a/drivers/clk/clkdev.c
+++ b/drivers/clk/clkdev.c
@@ -83,6 +83,31 @@
 }
 EXPORT_SYMBOL(clk_get);
 
+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);
+
 void clk_put(struct clk *clk)
 {
 	__clk_put(clk);