dm: usb: Move storage device scanning into its own function

The usb_stor_scan() function is quite long, so split out the code that scans
each device into its own function. Also, rather than setting up the block
device list once at the start, set it up as each device is scanned. This
makes it possible to use this code from driver model.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Marek Vasut <marex@denx.de>

common/usb_storage.c

@@ -33,6 +33,7 @@
 
 #include <common.h>
 #include <command.h>
+#include <errno.h>
 #include <inttypes.h>
 #include <mapmem.h>
 #include <asm/byteorder.h>
@@ -168,6 +169,60 @@ static unsigned int usb_get_max_lun(struct us_data *us)
 	return (len > 0) ? *result : 0;
 }
 
+static int usb_stor_probe_device(struct usb_device *dev)
+{
+	if (dev == NULL)
+		return -ENOENT; /* no more devices available */
+
+	debug("\n\nProbing for storage\n");
+	if (usb_storage_probe(dev, 0, &usb_stor[usb_max_devs])) {
+		/* OK, it's a storage device.  Iterate over its LUNs
+			* and populate `usb_dev_desc'.
+			*/
+		int lun, max_lun, start = usb_max_devs;
+
+		max_lun = usb_get_max_lun(&usb_stor[usb_max_devs]);
+		for (lun = 0;
+			lun <= max_lun && usb_max_devs < USB_MAX_STOR_DEV;
+			lun++) {
+			struct block_dev_desc *blkdev;
+
+			blkdev = &usb_dev_desc[usb_max_devs];
+			memset(blkdev, '\0', sizeof(block_dev_desc_t));
+			blkdev->if_type = IF_TYPE_USB;
+			blkdev->dev = usb_max_devs;
+			blkdev->part_type = PART_TYPE_UNKNOWN;
+			blkdev->target = 0xff;
+			blkdev->type = DEV_TYPE_UNKNOWN;
+			blkdev->block_read = usb_stor_read;
+			blkdev->block_write = usb_stor_write;
+			blkdev->lun = lun;
+			blkdev->priv = dev;
+
+			if (usb_stor_get_info(dev, &usb_stor[start],
+					      &usb_dev_desc[usb_max_devs]) ==
+					      1) {
+				usb_max_devs++;
+				debug("%s: Found device %p\n", __func__, dev);
+			}
+		}
+	}
+
+	/* if storage device */
+	if (usb_max_devs == USB_MAX_STOR_DEV) {
+		printf("max USB Storage Device reached: %d stopping\n",
+		       usb_max_devs);
+		return -ENOSPC;
+	}
+
+	return 0;
+}
+
+void usb_stor_reset(void)
+{
+	usb_max_devs = 0;
+}
+
 /*******************************************************************************
  * scan the usb and reports device info
  * to the user if mode = 1
@@ -176,54 +231,20 @@ static unsigned int usb_get_max_lun(struct us_data *us)
 int usb_stor_scan(int mode)
 {
 	unsigned char i;
-	struct usb_device *dev;
 
 	if (mode == 1)
 		printf("       scanning usb for storage devices... ");
 
 	usb_disable_asynch(1); /* asynch transfer not allowed */
 
-	for (i = 0; i < USB_MAX_STOR_DEV; i++) {
-		memset(&usb_dev_desc[i], 0, sizeof(block_dev_desc_t));
-		usb_dev_desc[i].if_type = IF_TYPE_USB;
-		usb_dev_desc[i].dev = i;
-		usb_dev_desc[i].part_type = PART_TYPE_UNKNOWN;
-		usb_dev_desc[i].target = 0xff;
-		usb_dev_desc[i].type = DEV_TYPE_UNKNOWN;
-		usb_dev_desc[i].block_read = usb_stor_read;
-		usb_dev_desc[i].block_write = usb_stor_write;
-	}
-
-	usb_max_devs = 0;
+	usb_stor_reset();
 	for (i = 0; i < USB_MAX_DEVICE; i++) {
+		struct usb_device *dev;
+
 		dev = usb_get_dev_index(i); /* get device */
 		debug("i=%d\n", i);
-		if (dev == NULL)
-			break; /* no more devices available */
-
-		if (usb_storage_probe(dev, 0, &usb_stor[usb_max_devs])) {
-			/* OK, it's a storage device.  Iterate over its LUNs
-			 * and populate `usb_dev_desc'.
-			 */
-			int lun, max_lun, start = usb_max_devs;
-
-			max_lun = usb_get_max_lun(&usb_stor[usb_max_devs]);
-			for (lun = 0;
-			     lun <= max_lun && usb_max_devs < USB_MAX_STOR_DEV;
-			     lun++) {
-				usb_dev_desc[usb_max_devs].lun = lun;
-				if (usb_stor_get_info(dev, &usb_stor[start],
-				    &usb_dev_desc[usb_max_devs]) == 1) {
-					usb_max_devs++;
-				}
-			}
-		}
-		/* if storage device */
-		if (usb_max_devs == USB_MAX_STOR_DEV) {
-			printf("max USB Storage Device reached: %d stopping\n",
-				usb_max_devs);
+		if (usb_stor_probe_device(dev))
 			break;
-		}
 	} /* for */
 
 	usb_disable_asynch(0); /* asynch transfer allowed */