[S] Change in coreboot[main]: ec/intel: read board ID one time from EC per stage

[Jérémy Compostella (Code Review)]

Attention is currently required from: Bora Guvendik, Cliff Huang, Jamie Ryu, Wonkyu Kim.

Jérémy Compostella has posted comments on this change by Wonkyu Kim. ( https://review.coreboot.org/c/coreboot/+/87247?usp=email )

Change subject: ec/intel: read board ID one time from EC per stage
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Patch Set 5:

(1 comment)

File src/ec/intel/board_id.c:

https://review.coreboot.org/c/coreboot/+/87247/comment/55699662_ea8256bd?usp... :
PS5, Line 21: get_rvp_board_id
We could actually make this function much flatter and read-able in my opinion. What do you think of the following?

int get_rvp_board_id(void)
    {
            static int id = BOARD_ID_UNKNOWN;
            char *ec_system;

/* Reading board ID after the first time reading. */
            if (id != BOARD_ID_UNKNOWN)
                    return id;

/* Reading from EC failed. */
            if (id == BOARD_ID_INIT)
                    return BOARD_ID_UNKNOWN;

/* Reading board ID for the first time. */
            /* Chrome_EC */
            if (CONFIG(EC_GOOGLE_CHROMEEC)) {
                    ec_system = "ChromeEC";
                    id = get_board_id_via_ext_ec();
                    goto done;
            }

/* Windows EC */
            if (send_ec_command(EC_FAB_ID_CMD) != 0) {
                    id = BOARD_ID_INIT;
                    goto out;
            }

ec_system = "WinEC";
            id = recv_ec_data() << 8;
            id |= recv_ec_data();

done:
            id &= BOARD_ID_MASK;
            printk(BIOS_INFO, "[%s] board id: 0x%x\n", ec_system, id);
    out:
            return id;
    }