Function ec_hash_image

src/security/vboot/ec_sync.c:107–184

* Asks the EC to calculate a hash of the specified firmware image, and * returns the information in **hash and *hash_size. */

 * returns the information in **hash and *hash_size.
 */
static vb2_error_t ec_hash_image(enum vb2_firmware_selection select,
				 const uint8_t **hash, int *hash_size)
{
	static struct ec_response_vboot_hash resp;
	uint32_t hash_offset;
	int recalc_requested = 0;
	struct stopwatch sw;

	hash_offset = get_vboot_hash_offset(select);

	stopwatch_init_msecs_expire(&sw, CROS_EC_HASH_TIMEOUT_MS);
	do {
		if (google_chromeec_get_vboot_hash(hash_offset, &resp))
			return VB2_ERROR_UNKNOWN;

		switch (resp.status) {
		case EC_VBOOT_HASH_STATUS_NONE:
			/*
			 * There is no hash available right now.
			 * Request a recalc if it hasn't been done yet.
			 */
			if (recalc_requested)
				break;

			printk(BIOS_WARNING,
			       "%s: No valid hash (status=%d size=%d). "
			       "Computing...\n", __func__, resp.status,
			       resp.size);

			if (google_chromeec_start_vboot_hash(
				    EC_VBOOT_HASH_TYPE_SHA256, hash_offset, &resp))
				return VB2_ERROR_UNKNOWN;

			recalc_requested = 1;

			/*
			 * Expect status to be busy since we just sent
			 * a recalc request.
			 */
			resp.status = EC_VBOOT_HASH_STATUS_BUSY;

			/* Hash just started calculating, let it go for a bit */
			mdelay(CROS_EC_HASH_CHECK_DELAY_MS);
			break;

		case EC_VBOOT_HASH_STATUS_BUSY:
			/* Hash is still calculating. */
			mdelay(CROS_EC_HASH_CHECK_DELAY_MS);
			break;

		case EC_VBOOT_HASH_STATUS_DONE: /* intentional fallthrough */
		default:
			/* Hash is ready! */
			break;
		}
	} while (resp.status == EC_VBOOT_HASH_STATUS_BUSY &&
		 !stopwatch_expired(&sw));