mtd: mpc5121_nfc: cleanup clock API use

use devm_clk_get() for automatic put after device close, check for and
propagate errors when enabling clocks, need to prepare clocks before
they can get enabled, adjust error code paths to correctly balance
get/put and prepare/unprepare and enable/disable calls
Signed-off-by: Gerhard Sittig <gsi@denx.de>
Signed-off-by: Anatolij Gustschin <agust@denx.de>

drivers/mtd/nand/mpc5121_nfc.c

@@ -617,10 +617,8 @@ static void mpc5121_nfc_free(struct device *dev, struct mtd_info *mtd)
 	struct nand_chip *chip = mtd->priv;
 	struct mpc5121_nfc_prv *prv = chip->priv;
 
-	if (prv->clk) {
-		clk_disable(prv->clk);
-		clk_put(prv->clk);
-	}
+	if (prv->clk)
+		clk_disable_unprepare(prv->clk);
 
 	if (prv->csreg)
 		iounmap(prv->csreg);
@@ -629,6 +627,7 @@ static void mpc5121_nfc_free(struct device *dev, struct mtd_info *mtd)
 static int mpc5121_nfc_probe(struct platform_device *op)
 {
 	struct device_node *rootnode, *dn = op->dev.of_node;
+	struct clk *clk;
 	struct device *dev = &op->dev;
 	struct mpc5121_nfc_prv *prv;
 	struct resource res;
@@ -730,14 +729,18 @@ static int mpc5121_nfc_probe(struct platform_device *op)
 	of_node_put(rootnode);
 
 	/* Enable NFC clock */
-	prv->clk = clk_get(dev, "nfc_clk");
-	if (IS_ERR(prv->clk)) {
+	clk = devm_clk_get(dev, "nfc_clk");
+	if (IS_ERR(clk)) {
 		dev_err(dev, "Unable to acquire NFC clock!\n");
-		retval = PTR_ERR(prv->clk);
+		retval = PTR_ERR(clk);
 		goto error;
 	}
-
-	clk_enable(prv->clk);
+	retval = clk_prepare_enable(clk);
+	if (retval) {
+		dev_err(dev, "Unable to enable NFC clock!\n");
+		goto error;
+	}
+	prv->clk = clk;
 
 	/* Reset NAND Flash controller */
 	nfc_set(mtd, NFC_CONFIG1, NFC_RESET);