dm: blk: Rename get_device() to blk_get_device_by_str()

The current name is too generic. The function returns a block device based
on a provided string. Rename it to aid searching and make its purpose
clearer. Also add a few comments.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Stephen Warren <swarren@nvidia.com>

cmd/part.c

@@ -81,7 +81,7 @@ static int do_part_list(int argc, char * const argv[])
 			return CMD_RET_USAGE;
 	}
 
-	ret = get_device(argv[0], argv[1], &desc);
+	ret = blk_get_device_by_str(argv[0], argv[1], &desc);
 	if (ret < 0)
 		return 1;
 
@@ -128,7 +128,7 @@ static int do_part_start(int argc, char * const argv[])
 
 	part = simple_strtoul(argv[2], NULL, 0);
 
-	ret = get_device(argv[0], argv[1], &desc);
+	ret = blk_get_device_by_str(argv[0], argv[1], &desc);
 	if (ret < 0)
 		return 1;
 
@@ -162,7 +162,7 @@ static int do_part_size(int argc, char * const argv[])
 
 	part = simple_strtoul(argv[2], NULL, 0);
 
-	ret = get_device(argv[0], argv[1], &desc);
+	ret = blk_get_device_by_str(argv[0], argv[1], &desc);
 	if (ret < 0)
 		return 1;
 

cmd/unzip.c

@@ -53,7 +53,7 @@ static int do_gzwrite(cmd_tbl_t *cmdtp, int flag,
 
 	if (argc < 5)
 		return CMD_RET_USAGE;
-	ret = get_device(argv[1], argv[2], &bdev);
+	ret = blk_get_device_by_str(argv[1], argv[2], &bdev);
 	if (ret < 0)
 		return CMD_RET_FAILURE;
 

cmd/usb_mass_storage.c

@@ -69,7 +69,7 @@ static int ums_init(const char *devtype, const char *devnums)
 		if (!devnum)
 			break;
 
-		ret = get_device(devtype, devnum, &block_dev);
+		ret = blk_get_device_by_str(devtype, devnum, &block_dev);
 		if (ret < 0)
 			goto cleanup;
 

disk/part.c

@@ -449,8 +449,8 @@ int get_partition_info(struct blk_desc *dev_desc, int part,
 	return -1;
 }
 
-int get_device(const char *ifname, const char *dev_hwpart_str,
-	       struct blk_desc **dev_desc)
+int blk_get_device_by_str(const char *ifname, const char *dev_hwpart_str,
+			  struct blk_desc **dev_desc)
 {
 	char *ep;
 	char *dup_str = NULL;
@@ -598,7 +598,7 @@ int get_device_and_partition(const char *ifname, const char *dev_part_str,
 	}
 
 	/* Look up the device */
-	dev = get_device(ifname, dev_str, dev_desc);
+	dev = blk_get_device_by_str(ifname, dev_str, dev_desc);
 	if (dev < 0)
 		goto cleanup;
 

include/part.h

@@ -101,8 +101,34 @@ int get_partition_info(struct blk_desc *dev_desc, int part,
 void print_part(struct blk_desc *dev_desc);
 void init_part(struct blk_desc *dev_desc);
 void dev_print(struct blk_desc *dev_desc);
-int get_device(const char *ifname, const char *dev_str,
-	       struct blk_desc **dev_desc);
+
+/**
+ * blk_get_device_by_str() - Get a block device given its interface/hw partition
+ *
+ * Each interface allocates its own devices and typically struct blk_desc is
+ * contained with the interface's data structure. There is no global
+ * numbering for block devices, so the interface name must be provided.
+ *
+ * The hardware parition is not related to the normal software partitioning
+ * of a device - each hardware partition is effectively a separately
+ * accessible block device. When a hardware parition is selected on MMC the
+ * other hardware partitions become inaccessible. The same block device is
+ * used to access all hardware partitions, but its capacity may change when a
+ * different hardware partition is selected.
+ *
+ * When a hardware partition number is given, the block device switches to
+ * that hardware partition.
+ *
+ * @ifname:	Interface name (e.g. "ide", "scsi")
+ * @dev_str:	Device and optional hw partition. This can either be a string
+ *		containing the device number (e.g. "2") or the device number
+ *		and hardware partition number (e.g. "2.4") for devices that
+ *		support it (currently only MMC).
+ * @dev_desc:	Returns a pointer to the block device on success
+ * @return block device number (local to the interface), or -1 on error
+ */
+int blk_get_device_by_str(const char *ifname, const char *dev_str,
+			  struct blk_desc **dev_desc);
 int get_device_and_partition(const char *ifname, const char *dev_part_str,
 			     struct blk_desc **dev_desc,
 			     disk_partition_t *info, int allow_whole_dev);
@@ -124,8 +150,8 @@ static inline int get_partition_info(struct blk_desc *dev_desc, int part,
 static inline void print_part(struct blk_desc *dev_desc) {}
 static inline void init_part(struct blk_desc *dev_desc) {}
 static inline void dev_print(struct blk_desc *dev_desc) {}
-static inline int get_device(const char *ifname, const char *dev_str,
-			     struct blk_desc **dev_desc)
+static inline int blk_get_device_by_str(const char *ifname, const char *dev_str,
+					struct blk_desc **dev_desc)
 { return -1; }
 static inline int get_device_and_partition(const char *ifname,
 					   const char *dev_part_str,

test/dm/usb.c

@@ -45,7 +45,7 @@ static int dm_test_usb_flash(struct unit_test_state *uts)
 	state_set_skip_delays(true);
 	ut_assertok(usb_init());
 	ut_assertok(uclass_get_device(UCLASS_MASS_STORAGE, 0, &dev));
-	ut_assertok(get_device("usb", "0", &dev_desc));
+	ut_assertok(blk_get_device_by_str("usb", "0", &dev_desc));
 
 	/* Read a few blocks and look for the string we expect */
 	ut_asserteq(512, dev_desc->blksz);