clk: Add error handling to clk_fetch_parent_index()

There are at least two different error cases that can happen in
clk_fetch_parent_index() function:
 - allocation failure,
 - parent clock lookup failure,
however it returns only an u8, which is supposed to contain parent clock
index.

This patch modified the function to return full int instead allowing
positive clock indices and negative error codes to be returned. All
users of this function are adjusted as well to handle the return value
correctly.

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index a004769..9e0a837 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -1080,13 +1080,16 @@
 }
 EXPORT_SYMBOL_GPL(clk_get_rate);
 
-static u8 clk_fetch_parent_index(struct clk *clk, struct clk *parent)
+static int clk_fetch_parent_index(struct clk *clk, struct clk *parent)
 {
-	u8 i;
+	int i;
 
-	if (!clk->parents)
+	if (!clk->parents) {
 		clk->parents = kzalloc((sizeof(struct clk*) * clk->num_parents),
 								GFP_KERNEL);
+		if (!clk->parents)
+			return -ENOMEM;
+	}
 
 	/*
 	 * find index of new parent clock using cached parent ptrs,
@@ -1095,15 +1098,15 @@
 	 */
 	for (i = 0; i < clk->num_parents; i++) {
 		if (clk->parents && clk->parents[i] == parent)
-			break;
+			return i;
 		else if (!strcmp(clk->parent_names[i], parent->name)) {
 			if (clk->parents)
 				clk->parents[i] = __clk_lookup(parent->name);
-			break;
+			return i;
 		}
 	}
 
-	return i;
+	return -EINVAL;
 }
 
 static void clk_reparent(struct clk *clk, struct clk *new_parent)
@@ -1265,7 +1268,7 @@
 	struct clk *old_parent, *parent;
 	unsigned long best_parent_rate = 0;
 	unsigned long new_rate;
-	u8 p_index = 0;
+	int p_index = 0;
 
 	/* sanity */
 	if (IS_ERR_OR_NULL(clk))
@@ -1306,7 +1309,7 @@
 	/* try finding the new parent index */
 	if (parent) {
 		p_index = clk_fetch_parent_index(clk, parent);
-		if (p_index == clk->num_parents) {
+		if (p_index < 0) {
 			pr_debug("%s: clk %s can not be parent of clk %s\n",
 				 __func__, parent->name, clk->name);
 			return NULL;
@@ -1568,7 +1571,7 @@
 int clk_set_parent(struct clk *clk, struct clk *parent)
 {
 	int ret = 0;
-	u8 p_index = 0;
+	int p_index = 0;
 	unsigned long p_rate = 0;
 
 	if (!clk)
@@ -1597,10 +1600,10 @@
 	if (parent) {
 		p_index = clk_fetch_parent_index(clk, parent);
 		p_rate = parent->rate;
-		if (p_index == clk->num_parents) {
+		if (p_index < 0) {
 			pr_debug("%s: clk %s can not be parent of clk %s\n",
 					__func__, parent->name, clk->name);
-			ret = -EINVAL;
+			ret = p_index;
 			goto out;
 		}
 	}