sparse: Implement several chunks flashing

The fastboot client will split the sparse images into several chunks if the
image that it tries to flash is bigger than what the device can handle.

In such a case, the bootloader is supposed to retain the last offset to
which it wrote to, so that it can resume the writes at the right offset
when flashing the next chunk.

Retain the last offset we used, and use the session ID to know if we need
it or not.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: Tom Rini <trini@konsulko.com>

common/aboot.c

@@ -52,6 +52,8 @@ typedef struct sparse_buffer {
 	u16	type;
 } sparse_buffer_t;
 
+static uint32_t last_offset;
+
 static unsigned int sparse_get_chunk_data_size(sparse_header_t *sparse,
 					       chunk_header_t *chunk)
 {
@@ -301,10 +303,19 @@ int store_sparse_image(sparse_storage_t *storage, void *storage_priv,
 		return -EINVAL;
 	}
 
-	puts("Flashing Sparse Image\n");
+	/*
+	 * If it's a new flashing session, start at the beginning of
+	 * the partition. If not, then simply resume where we were.
+	 */
+	if (session_id > 0)
+		start = last_offset;
+	else
+		start = storage->start;
+
+	printf("Flashing sparse image on partition %s at offset 0x%x (ID: %d)\n",
+	       storage->name, start * storage->block_sz, session_id);
 
 	/* Start processing chunks */
-	start = storage->start;
 	for (chunk = 0; chunk < sparse_header->total_chunks; chunk++) {
 		uint32_t blkcnt;
 
@@ -376,5 +387,7 @@ int store_sparse_image(sparse_storage_t *storage, void *storage_priv,
 		return -EIO;
 	}
 
+	last_offset = start + total_blocks;
+
 	return 0;
 }