libpayload: cros: add serial number from coreboot table

Add serial number to lib_sysinfo from coreboot table.

BRANCH=none
BUG=chrome-os-partner:37813
TEST=ryu boots and /proc/device-tree/firmware/android is populated
with "compatible", "hardware", and "serialno" properties

Change-Id: I565b332a16b177c51907ffab7976ebd7a665aaaf
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 5535119f5d499b04bdc178c3040241d2872c4e13
Original-Change-Id: Ie2e222780d1577689a1cbf76ae8514c74fc469f4
Original-Signed-off-by: Stephen Barber <smbarber@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/259140
Original-Reviewed-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: http://review.coreboot.org/9881
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

payloads/libpayload/include/coreboot_tables.h

@@ -256,6 +256,9 @@ struct cb_spi_flash {
 	uint32_t erase_cmd;
 };
 
+#define CB_TAG_SERIALNO		0x002a
+#define CB_MAX_SERIALNO_LENGTH	32
+
 #define CB_TAG_CMOS_OPTION_TABLE 0x00c8
 struct cb_cmos_option_table {
 	u32 tag;

payloads/libpayload/include/sysinfo.h

@@ -91,6 +91,7 @@ struct sysinfo_t {
 	struct cb_gpio gpios[SYSINFO_MAX_GPIOS];
 	int num_macs;
 	struct mac_address macs[SYSINFO_MAX_MACS];
+	char *serialno;
 #endif
 
 	unsigned long *mbtable; /** Pointer to the multiboot table */

payloads/libpayload/libc/coreboot.c

@@ -333,6 +333,9 @@ int cb_parse_header(void *addr, int len, struct sysinfo_t *info)
 		case CB_TAG_MAC_ADDRS:
 			cb_parse_mac_addresses(ptr, info);
 			break;
+		case CB_TAG_SERIALNO:
+			cb_parse_string(ptr, &info->serialno);
+			break;
 #endif
 		case CB_TAG_TIMESTAMPS:
 			cb_parse_tstamp(ptr, info);