Add PreBctPadBlocks config file option

This allows the BCT to be offset within the memory device. This is a port
of commit 883a7d0 "Add suport for MMC boot image preparation" from
git://gitorious.org/cbootimage/cbootimage.git's trimslice branch. The
description there is:

    Add suport for MMC boot image preparation

    In order to allow the MBR to be placed at offset 0,
    BCT is copied to 128K offset.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Change-Id: Icde53082f5a4645fefb70deb408a42f9920aed1f
Reviewed-on: https://gerrit.chromium.org/gerrit/22935
Reviewed-by: Simon Glass <sjg@chromium.org>

5 files changed, 28 insertions, 5 deletions

diff --git a/cbootimage.h b/cbootimage.h
index 783d82c..f901605 100644
--- a/cbootimage.h
+++ b/cbootimage.h
@@ -68,6 +68,13 @@ typedef struct build_image_context_rec
 	u_int32_t redundancy;
 	u_int32_t version;
 	u_int32_t bct_copy;
+	/*
+	 * Number of blocks at start of device to skip before the BCT.
+	 * This may be used to reserve space for a partition table, for
+	 * example, in order to write the resultant boot image to e.g. an
+	 * SD card while using the remaining space for a user filesystem.
+	 */
+	u_int32_t pre_bct_pad_blocks;
 	/* Allocation data. */
 	struct blk_data_rec *memory; /* Representation of memory */
 	/* block number for the BCT block */
diff --git a/data_layout.c b/data_layout.c
index d70f3b4..23fa830 100644
--- a/data_layout.c
+++ b/data_layout.c
@@ -783,13 +783,20 @@ begin_update(build_image_context *context)
 	/* Fill the reserved data w/the padding pattern. */
 	write_padding(context->bct + reserved_offset, reserved_size);
 
-	/* Find the next bct block starting at block 1. */
-	for (i = 0; i < context->bct_copy; i++) {
+	/* Create the pad before the BCT starting at block 1 */
+	for (i = 0; i < context->pre_bct_pad_blocks; i++) {
 		find_new_bct_blk(context);
 		err = erase_block(context, i);
 		if (err != 0)
 			goto fail;
 	}
+	/* Find the next bct block starting at block pre_bct_pad_blocks. */
+	for (i = 0; i < context->bct_copy; i++) {
+		find_new_bct_blk(context);
+		err = erase_block(context, i + context->pre_bct_pad_blocks);
+		if (err != 0)
+			goto fail;
+	}
 	return 0;
 fail:
 	printf("Erase block failed, error: %d.\n", err);
@@ -797,8 +804,7 @@ fail:
 }
 
 /*
- * Write the new BCT to the next available of the journal block.
- * Write the new BCT to slot 0 of block 0.
+ * Write the BCT(s) starting at slot 0 of block context->pre_bct_pad_blocks.
  *
  * @param context		The main context pointer
  * @return 0 for success
@@ -810,7 +816,7 @@ finish_update(build_image_context *context)
 	int i;
 
 	for (i = 0; i < context->bct_copy; i++) {
-		err = write_bct(context, i, 0);
+		err = write_bct(context, i + context->pre_bct_pad_blocks, 0);
 		if (err != 0)
 			goto fail;
 	}
diff --git a/parse.c b/parse.c
index 23bdf26..8cc7149 100644
--- a/parse.c
+++ b/parse.c
@@ -86,6 +86,7 @@ static parse_item parse_simple_items[] =
 	{ "Redundancy=",    token_redundancy,		parse_value_u32 },
 	{ "Bctcopy=",       token_bct_copy,		parse_value_u32 },
 	{ "Version=",       token_version,		parse_value_u32 },
+	{ "PreBctPadBlocks=", token_pre_bct_pad_blocks,	parse_value_u32 },
 	{ NULL, 0, NULL } /* Must be last */
 };
 
diff --git a/parse.h b/parse.h
index fd87427..5c59045 100644
--- a/parse.h
+++ b/parse.h
@@ -110,6 +110,7 @@ typedef enum
 	token_dev_type_sdmmc,
 	token_dev_type_spi,
 	token_num_sdram_sets,
+	token_pre_bct_pad_blocks,
 
 	token_nand_clock_divider,
 	token_nand_nand_timing,
diff --git a/set.c b/set.c
index 9d3c1d1..eb04bab 100644
--- a/set.c
+++ b/set.c
@@ -194,6 +194,14 @@ int context_set_value(build_image_context *context,
 		context->odm_data = value;
 		break;
 
+	case token_pre_bct_pad_blocks:
+		if (context->bct_init != NULL) {
+			printf("Error: Too late to pre-BCT pad.\n");
+			return 1;
+		}
+		context->pre_bct_pad_blocks = value;
+		break;
+
 	DEFAULT();
 	}