Add a command to read raw blocks from a partition

Sometimes data is on a block device and within a partition, but not in a
particular filesystem.

This commands permits reading raw data from a partition.

Signed-off-by: Kenneth Waters <kwaters@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>

common/cmd_read.c

@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ * Alternatively, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2 as published by the Free
+ * Software Foundation.
+ */
+
+#include <common.h>
+#include <command.h>
+#include <part.h>
+
+int do_read(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	char *ep;
+	block_dev_desc_t *dev_desc = NULL;
+	int dev;
+	int part = 0;
+	disk_partition_t part_info;
+	ulong offset = 0u;
+	ulong limit = 0u;
+	void *addr;
+	uint blk;
+	uint cnt;
+
+	if (argc != 6) {
+		cmd_usage(cmdtp);
+		return 1;
+	}
+
+	dev = (int)simple_strtoul(argv[2], &ep, 16);
+	if (*ep) {
+		if (*ep != ':') {
+			printf("Invalid block device %s\n", argv[2]);
+			return 1;
+		}
+		part = (int)simple_strtoul(++ep, NULL, 16);
+	}
+
+	dev_desc = get_dev(argv[1], dev);
+	if (dev_desc == NULL) {
+		printf("Block device %s %d not supported\n", argv[1], dev);
+		return 1;
+	}
+
+	addr = (void *)simple_strtoul(argv[3], NULL, 16);
+	blk = simple_strtoul(argv[4], NULL, 16);
+	cnt = simple_strtoul(argv[5], NULL, 16);
+
+	if (part != 0) {
+		if (get_partition_info(dev_desc, part, &part_info)) {
+			printf("Cannot find partition %d\n", part);
+			return 1;
+		}
+		offset = part_info.start;
+		limit = part_info.size;
+	} else {
+		/* Largest address not available in block_dev_desc_t. */
+		limit = ~0;
+	}
+
+	if (cnt + blk > limit) {
+		printf("Read out of range\n");
+		return 1;
+	}
+
+	if (dev_desc->block_read(dev, offset + blk, cnt, addr) < 0) {
+		printf("Error reading blocks\n");
+		return 1;
+	}
+
+	return 0;
+}
+
+U_BOOT_CMD(
+	read,	6,	0,	do_read,
+	"Load binary data from a partition",
+	"<interface> <dev[:part]> addr blk# cnt"
+);