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>

drivers/clk/clk.c

@@ -1080,13 +1080,16 @@ unsigned long clk_get_rate(struct clk *clk)
 }
 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 @@ static u8 clk_fetch_parent_index(struct clk *clk, struct clk *parent)
 	 */
 	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 @@ static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate)
 	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 @@ static struct clk *clk_calc_new_rates(struct clk *clk, unsigned long rate)
 	/* 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 @@ void __clk_reparent(struct clk *clk, struct clk *new_parent)
 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 @@ int clk_set_parent(struct clk *clk, struct clk *parent)
 	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;
 		}
 	}