spi: use class iteration api

Convert to use the class iteration api.
Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Acked-by: David Brownell <david-b@pacbell.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/spi/spi.c

@@ -485,6 +485,15 @@ void spi_unregister_master(struct spi_master *master)
 }
 EXPORT_SYMBOL_GPL(spi_unregister_master);
 
+static int __spi_master_match(struct device *dev, void *data)
+{
+	struct spi_master *m;
+	u16 *bus_num = data;
+
+	m = container_of(dev, struct spi_master, dev);
+	return m->bus_num == *bus_num;
+}
+
 /**
  * spi_busnum_to_master - look up master associated with bus_num
  * @bus_num: the master's bus number
@@ -499,17 +508,12 @@ struct spi_master *spi_busnum_to_master(u16 bus_num)
 {
 	struct device		*dev;
 	struct spi_master	*master = NULL;
-	struct spi_master	*m;
-
-	down(&spi_master_class.sem);
-	list_for_each_entry(dev, &spi_master_class.children, node) {
-		m = container_of(dev, struct spi_master, dev);
-		if (m->bus_num == bus_num) {
-			master = spi_master_get(m);
-			break;
-		}
-	}
-	up(&spi_master_class.sem);
+
+	dev = class_find_device(&spi_master_class, &bus_num,
+				__spi_master_match);
+	if (dev)
+		master = container_of(dev, struct spi_master, dev);
+	/* reference got in class_find_device */
 	return master;
 }
 EXPORT_SYMBOL_GPL(spi_busnum_to_master);