cmd: new mac_from_mmc command

cmd/Kconfig

@@ -1288,6 +1288,12 @@ config CMD_MMC_REG
 	  Enable the commands for reading card registers. This is useful
 	  mostly for debugging or extracting details from the card.
 
+config CMD_MAC_FROM_MMC
+    bool "mac form mmc cid"
+    depends on CMD_MMC
+    help
+      Enable command for forming a MAC address from the CID of a eMMC device.
+
 config CMD_MMC_RPMB
 	bool "Enable support for RPMB in the mmc command"
 	depends on SUPPORT_EMMC_RPMB

cmd/Makefile

@@ -115,6 +115,7 @@ obj-$(CONFIG_CMD_MDIO) += mdio.o
 obj-$(CONFIG_CMD_PAUSE) += pause.o
 obj-$(CONFIG_CMD_SLEEP) += sleep.o
 obj-$(CONFIG_CMD_MMC) += mmc.o
+obj-$(CONFIG_CMD_MAC_FROM_MMC) += mac_from_emmc.o
 obj-$(CONFIG_CMD_OPTEE_RPMB) += optee_rpmb.o
 obj-$(CONFIG_CMD_MP) += mp.o
 obj-$(CONFIG_CMD_MTD) += mtd.o

cmd/mac_from_emmc.c

@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2024 Alchemilla Ventures Private Limited <hayzam@alchemilla.io>
+ */
+
+#include <common.h>
+#include <command.h>
+#include <console.h>
+#include <mmc.h>
+
+static int do_mac_from_mmc(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) {
+    if (argc != 2) {
+        return CMD_RET_USAGE;
+    }
+
+    int currentDevice = simple_strtoul(argv[1], NULL, 10);
+    struct mmc *mmc = find_mmc_device(currentDevice);
+
+    if (!mmc) {
+        printf("No MMC device at slot %d\n", currentDevice);
+        return CMD_RET_FAILURE;
+    }
+
+    if (IS_SD(mmc)) {
+        printf("SD registers are not supported\n");
+        return CMD_RET_FAILURE;
+    }
+
+    unsigned char mac[6];
+    mac[0] = (mmc->cid[0] >> 24) & 0xFE;
+    mac[1] = (mmc->cid[1] >> 16) & 0xFF;
+    mac[2] = (mmc->cid[2] >> 8) & 0xFF;
+    mac[3] = (mmc->cid[3]) & 0xFF;
+    mac[4] = (mmc->cid[0] >> 8) & 0xFF;
+    mac[5] = (mmc->cid[1] >> 24) & 0xFF;
+
+    printf("MAC Address: %02X:%02X:%02X:%02X:%02X:%02X\n",
+           mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
+
+    return CMD_RET_SUCCESS;
+}
+
+U_BOOT_CMD(
+    mac_from_mmc, 2, 0, do_mac_from_mmc,
+    "Get MAC address from MMC CID",
+    "mmc"
+);