diff --git a/arch/arm/mach-imx/imx8m/Kconfig b/arch/arm/mach-imx/imx8m/Kconfig
index 276b8bd974..bd2a7d6820 100644
--- a/arch/arm/mach-imx/imx8m/Kconfig
+++ b/arch/arm/mach-imx/imx8m/Kconfig
@@ -147,6 +147,7 @@ config TARGET_IMX8MM_CL_IOT_GATE
 	select IMX8MM
 	select SUPPORT_SPL
 	select IMX8M_LPDDR4
+	select SUPPORT_EXTENSION_SCAN
 
 config TARGET_IMX8MM_CL_IOT_GATE_OPTEE
 	bool "CompuLab iot-gate-imx8 with optee support"
@@ -154,6 +155,7 @@ config TARGET_IMX8MM_CL_IOT_GATE_OPTEE
 	select IMX8MM
 	select SUPPORT_SPL
 	select IMX8M_LPDDR4
+	select SUPPORT_EXTENSION_SCAN
 endchoice
 
 source "board/beacon/imx8mm/Kconfig"
diff --git a/board/compulab/imx8mm-cl-iot-gate/imx8mm-cl-iot-gate.c b/board/compulab/imx8mm-cl-iot-gate/imx8mm-cl-iot-gate.c
index cd15410978..7e2d88f449 100644
--- a/board/compulab/imx8mm-cl-iot-gate/imx8mm-cl-iot-gate.c
+++ b/board/compulab/imx8mm-cl-iot-gate/imx8mm-cl-iot-gate.c
@@ -6,14 +6,21 @@
 
 #include <common.h>
 #include <env.h>
+#include <extension_board.h>
 #include <hang.h>
+#include <i2c.h>
 #include <init.h>
 #include <miiphy.h>
 #include <netdev.h>
 
 #include <asm/arch/clock.h>
+#include <asm/arch/imx8mm_pins.h>
 #include <asm/arch/sys_proto.h>
+#include <asm/global_data.h>
 #include <asm/io.h>
+#include <asm/mach-imx/gpio.h>
+#include <asm/mach-imx/mxc_i2c.h>
+#include <asm/sections.h>
 
 #include "ddr/ddr.h"
 
@@ -41,6 +48,25 @@ int board_phys_sdram_size(phys_size_t *size)
 	return 0;
 }
 
+/* IOT_GATE-iMX8 extension boards ID */
+typedef enum {
+	IOT_GATE_EXT_EMPTY, /* No extension */
+	IOT_GATE_EXT_CAN,   /* CAN bus */
+	IOT_GATE_EXT_IED,   /* Bridge */
+	IOT_GATE_EXT_POE,   /* POE */
+	IOT_GATE_EXT_POEV2, /* POEv2 */
+} iot_gate_imx8_ext;
+
+typedef enum {
+	IOT_GATE_IMX8_CARD_ID_EMPTY = 0,  /* card id - uninhabited */
+	IOT_GATE_IMX8_CARD_ID_DI4O4 = 1,  /* Card ID - IED-DI4O4   */
+	IOT_GATE_IMX8_CARD_ID_RS_485 = 2, /* Card ID - IED-RS485   */
+	IOT_GATE_IMX8_CARD_ID_TPM = 3,    /* Card ID - IED-TPM     */
+	IOT_GATE_IMX8_CARD_ID_CAN = 4,    /* Card ID - IED-CAN     */
+	IOT_GATE_IMX8_CARD_ID_CL420 = 5,  /* Card ID - IED-CL420   */
+	IOT_GATE_IMX8_CARD_ID_RS_232 = 6, /* Card ID - IED-RS232   */
+} iot_gate_imx8_ied_ext;
+
 static int setup_fec(void)
 {
 	if (IS_ENABLED(CONFIG_FEC_MXC)) {
@@ -85,6 +111,313 @@ int board_mmc_get_env_dev(int devno)
 	return devno;
 }
 
+#define IOT_GATE_IMX8_EXT_I2C 3 /* I2C ID of the extension board */
+#define IOT_GATE_IMX8_EXT_I2C_ADDR_EEPROM 0x54 /* I2C address of the EEPROM */
+
+/* I2C address of the EEPROM in the POE extension */
+#define IOT_GATE_IMX8_EXT_I2C_ADDR_EEPROM_POE 0x50
+#define IOT_GATE_IMX8_EXT_I2C_ADDR_EEPROM_POEV2 0x51
+#define IOT_GATE_IMX8_EXT_I2C_ADDR_GPIO 0x22 /* I2C address of the GPIO
+						extender */
+
+static int iot_gate_imx8_ext_id = IOT_GATE_EXT_EMPTY; /* Extension board ID */
+static int iot_gate_imx8_ext_ied_id [3] = {
+	IOT_GATE_IMX8_CARD_ID_EMPTY,
+	IOT_GATE_IMX8_CARD_ID_EMPTY,
+	IOT_GATE_IMX8_CARD_ID_EMPTY };
+
+/*
+ * iot_gate_imx8_detect_ext() - extended board detection
+ * The detection is done according to the detected I2C devices.
+ */
+static void iot_gate_imx8_detect_ext(void)
+{
+	int ret;
+	struct udevice *i2c_bus, *i2c_dev;
+
+	ret = uclass_get_device_by_seq(UCLASS_I2C, IOT_GATE_IMX8_EXT_I2C,
+				       &i2c_bus);
+	if (ret) {
+		printf("%s: Failed getting i2c device\n", __func__);
+		return;
+	}
+
+	ret = dm_i2c_probe(i2c_bus, IOT_GATE_IMX8_EXT_I2C_ADDR_EEPROM_POE, 0,
+			   &i2c_dev);
+	if (!ret) {
+		iot_gate_imx8_ext_id = IOT_GATE_EXT_POE;
+		return;
+	}
+
+	ret = dm_i2c_probe(i2c_bus, IOT_GATE_IMX8_EXT_I2C_ADDR_EEPROM_POEV2, 0,
+			   &i2c_dev);
+	if (!ret) {
+		iot_gate_imx8_ext_id = IOT_GATE_EXT_POEV2;
+		return;
+	}
+
+	ret = dm_i2c_probe(i2c_bus, IOT_GATE_IMX8_EXT_I2C_ADDR_EEPROM, 0,
+			   &i2c_dev);
+	if (ret){
+		iot_gate_imx8_ext_id = IOT_GATE_EXT_EMPTY;
+		return;
+	}
+	/* Only the bridge extension includes the GPIO extender */
+	ret = dm_i2c_probe(i2c_bus, IOT_GATE_IMX8_EXT_I2C_ADDR_GPIO, 0,
+			   &i2c_dev);
+	if (ret) /* GPIO extender not detected */
+		iot_gate_imx8_ext_id = IOT_GATE_EXT_CAN;
+	else /* GPIO extender detected */
+		iot_gate_imx8_ext_id = IOT_GATE_EXT_IED;
+}
+
+static iomux_v3_cfg_t const iot_gate_imx8_ext_ied_pads[] = {
+	IMX8MM_PAD_NAND_ALE_GPIO3_IO0	 | MUX_PAD_CTRL(PAD_CTL_PE),
+	IMX8MM_PAD_NAND_CE0_B_GPIO3_IO1	 | MUX_PAD_CTRL(PAD_CTL_PE),
+	IMX8MM_PAD_NAND_DATA00_GPIO3_IO6 | MUX_PAD_CTRL(PAD_CTL_PE),
+	IMX8MM_PAD_NAND_DATA01_GPIO3_IO7 | MUX_PAD_CTRL(PAD_CTL_PE),
+	IMX8MM_PAD_NAND_DATA02_GPIO3_IO8 | MUX_PAD_CTRL(PAD_CTL_PE),
+	IMX8MM_PAD_NAND_DATA03_GPIO3_IO9 | MUX_PAD_CTRL(PAD_CTL_PE),
+};
+
+static iomux_v3_cfg_t const iot_gate_imx8_ext_poev2_pads[] = {
+	IMX8MM_PAD_SAI3_TXD_GPIO5_IO1	 | MUX_PAD_CTRL(PAD_CTL_PE |
+							PAD_CTL_PUE),
+};
+
+/* Extension board bridge GPIOs */
+#define IOT_GATE_IMX8_GPIO_EXT_IED_I0 IMX_GPIO_NR(3, 0) /* IN 0 */
+#define IOT_GATE_IMX8_GPIO_EXT_IED_I1 IMX_GPIO_NR(3, 1) /* IN 1 */
+#define IOT_GATE_IMX8_GPIO_EXT_IED_I2 IMX_GPIO_NR(3, 6) /* IN 2 */
+#define IOT_GATE_IMX8_GPIO_EXT_IED_I3 IMX_GPIO_NR(3, 7) /* IN 3 */
+#define IOT_GATE_IMX8_GPIO_EXT_IED_O0 IMX_GPIO_NR(3, 8) /* OUT 0 */
+#define IOT_GATE_IMX8_GPIO_EXT_IED_O1 IMX_GPIO_NR(3, 9) /* OUT 1 */
+#define IOT_GATE_IMX8_GPIO_EXT_IED_O2 IMX_GPIO_NR(6, 9) /* OUT 2 */
+#define IOT_GATE_IMX8_GPIO_EXT_IED_O3 IMX_GPIO_NR(6, 10)/* OUT 3 */
+
+/* Extension board POE GPIOs */
+#define IOT_GATE_IMX8_GPIO_EXT_POE_MUX IMX_GPIO_NR(5, 1)/* USB_MUX */
+
+/*
+ * iot_gate_imx8_update_pinmux() - update the pinmux
+ * Update the pinmux according to the detected extended board.
+ */
+static void iot_gate_imx8_update_pinmux(void)
+{
+	if (iot_gate_imx8_ext_id == IOT_GATE_EXT_POEV2) {
+		imx_iomux_v3_setup_multiple_pads(iot_gate_imx8_ext_poev2_pads,
+				ARRAY_SIZE(iot_gate_imx8_ext_poev2_pads));
+		gpio_request(IOT_GATE_IMX8_GPIO_EXT_POE_MUX, "poev2_usb-mux");
+		/* Update USB MUX state */
+		gpio_direction_output(IOT_GATE_IMX8_GPIO_EXT_POE_MUX, 1);
+
+		return;
+	}
+	if (iot_gate_imx8_ext_id != IOT_GATE_EXT_IED)
+		return;
+
+	imx_iomux_v3_setup_multiple_pads(iot_gate_imx8_ext_ied_pads,
+					 ARRAY_SIZE(iot_gate_imx8_ext_ied_pads));
+
+	gpio_request(IOT_GATE_IMX8_GPIO_EXT_IED_I0, "ied-di4o4_i0");
+	gpio_direction_input(IOT_GATE_IMX8_GPIO_EXT_IED_I0);
+	gpio_request(IOT_GATE_IMX8_GPIO_EXT_IED_I1, "ied-di4o4_i1");
+	gpio_direction_input(IOT_GATE_IMX8_GPIO_EXT_IED_I1);
+	gpio_request(IOT_GATE_IMX8_GPIO_EXT_IED_I2, "ied-di4o4_i2");
+	gpio_direction_input(IOT_GATE_IMX8_GPIO_EXT_IED_I2);
+	gpio_request(IOT_GATE_IMX8_GPIO_EXT_IED_I3, "ied-di4o4_i3");
+	gpio_direction_input(IOT_GATE_IMX8_GPIO_EXT_IED_I3);
+	gpio_request(IOT_GATE_IMX8_GPIO_EXT_IED_O0, "ied-di4o4_o0");
+	gpio_direction_output(IOT_GATE_IMX8_GPIO_EXT_IED_O0, 0);
+	gpio_request(IOT_GATE_IMX8_GPIO_EXT_IED_O1, "ied-di4o4_o1");
+	gpio_direction_output(IOT_GATE_IMX8_GPIO_EXT_IED_O1, 0);
+	gpio_request(IOT_GATE_IMX8_GPIO_EXT_IED_O2, "ied-di4o4_o2");
+	gpio_direction_output(IOT_GATE_IMX8_GPIO_EXT_IED_O2, 0);
+	gpio_request(IOT_GATE_IMX8_GPIO_EXT_IED_O3, "ied-di4o4_o3");
+	gpio_direction_output(IOT_GATE_IMX8_GPIO_EXT_IED_O3, 0);
+}
+
+#define IOT_GATE_IMX8_GPIO_S0B0 IMX_GPIO_NR(6, 0) /* Slot ID slot 0 bit 0 */
+#define IOT_GATE_IMX8_GPIO_S0B1 IMX_GPIO_NR(6, 1) /* Slot ID slot 0 bit 1 */
+#define IOT_GATE_IMX8_GPIO_S0B2 IMX_GPIO_NR(6, 2) /* Slot ID slot 0 bit 2 */
+#define IOT_GATE_IMX8_GPIO_S1B0 IMX_GPIO_NR(6, 3) /* Slot ID slot 1 bit 0 */
+#define IOT_GATE_IMX8_GPIO_S1B1 IMX_GPIO_NR(6, 4) /* Slot ID slot 1 bit 1 */
+#define IOT_GATE_IMX8_GPIO_S1B2 IMX_GPIO_NR(6, 5) /* Slot ID slot 1 bit 2 */
+#define IOT_GATE_IMX8_GPIO_S2B0 IMX_GPIO_NR(6, 6) /* Slot ID slot 2 bit 0 */
+#define IOT_GATE_IMX8_GPIO_S2B1 IMX_GPIO_NR(6, 7) /* Slot ID slot 2 bit 1 */
+#define IOT_GATE_IMX8_GPIO_S2B2 IMX_GPIO_NR(6, 8) /* Slot ID slot 2 bit 2 */
+
+/*
+ * iot_gate_imx8_update_ext_ied()
+ * Update device tree of the extended board IED-BASE.
+ * The device tree is updated according to the detected sub modules.
+ *
+ * Return 0 for success, 1 for failure.
+ */
+static int iot_gate_imx8_update_ext_ied(void)
+{
+	int revision;
+
+	if (iot_gate_imx8_ext_id != IOT_GATE_EXT_IED)
+		return 0;
+
+	/* ID GPIO initializations */
+	if (gpio_request(IOT_GATE_IMX8_GPIO_S0B0, "id_s0b0") ||
+	    gpio_request(IOT_GATE_IMX8_GPIO_S0B1, "id_s0b1") ||
+	    gpio_request(IOT_GATE_IMX8_GPIO_S0B2, "id_s0b2") ||
+	    gpio_request(IOT_GATE_IMX8_GPIO_S1B0, "id_s1b0") ||
+	    gpio_request(IOT_GATE_IMX8_GPIO_S1B1, "id_s1b1") ||
+	    gpio_request(IOT_GATE_IMX8_GPIO_S1B2, "id_s1b2") ||
+	    gpio_request(IOT_GATE_IMX8_GPIO_S2B0, "id_s2b0") ||
+	    gpio_request(IOT_GATE_IMX8_GPIO_S2B1, "id_s2b1") ||
+	    gpio_request(IOT_GATE_IMX8_GPIO_S2B2, "id_s2b2")) {
+		printf("%s: ID GPIO request failure\n", __func__);
+		return 1;
+	}
+	gpio_direction_input(IOT_GATE_IMX8_GPIO_S0B0);
+	gpio_direction_input(IOT_GATE_IMX8_GPIO_S0B1);
+	gpio_direction_input(IOT_GATE_IMX8_GPIO_S0B2);
+	gpio_direction_input(IOT_GATE_IMX8_GPIO_S1B0);
+	gpio_direction_input(IOT_GATE_IMX8_GPIO_S1B1);
+	gpio_direction_input(IOT_GATE_IMX8_GPIO_S1B2);
+	gpio_direction_input(IOT_GATE_IMX8_GPIO_S2B0);
+	gpio_direction_input(IOT_GATE_IMX8_GPIO_S2B1);
+	gpio_direction_input(IOT_GATE_IMX8_GPIO_S2B2);
+
+	/* Get slot 0 card ID */
+	revision =	gpio_get_value(IOT_GATE_IMX8_GPIO_S0B0)		|
+			gpio_get_value(IOT_GATE_IMX8_GPIO_S0B1) << 1	|
+			gpio_get_value(IOT_GATE_IMX8_GPIO_S0B2) << 2;
+	iot_gate_imx8_ext_ied_id[0] = revision;
+
+	/* Get slot 1 card ID */
+	revision =	gpio_get_value(IOT_GATE_IMX8_GPIO_S1B0)		|
+			gpio_get_value(IOT_GATE_IMX8_GPIO_S1B1) << 1	|
+			gpio_get_value(IOT_GATE_IMX8_GPIO_S1B2) << 2;
+	iot_gate_imx8_ext_ied_id[1] = revision;
+
+	/* Get slot 2 card ID */
+	revision =	gpio_get_value(IOT_GATE_IMX8_GPIO_S2B0)		|
+			gpio_get_value(IOT_GATE_IMX8_GPIO_S2B1) << 1	|
+			gpio_get_value(IOT_GATE_IMX8_GPIO_S2B2) << 2;
+	iot_gate_imx8_ext_ied_id[2] = revision;
+
+	return 0;
+}
+
+int board_fix_fdt(void *rw_fdt_blob)
+{
+	return 0;
+}
+
+int extension_board_scan(struct list_head *extension_list)
+{
+	struct extension *extension = NULL;
+	int i;
+	int ret = 0;
+
+	iot_gate_imx8_detect_ext(); /* Extended board detection */
+
+	switch(iot_gate_imx8_ext_id) {
+	case IOT_GATE_EXT_EMPTY:
+		break;
+	case IOT_GATE_EXT_CAN:
+		extension = calloc(1, sizeof(struct extension));
+		snprintf(extension->name, sizeof(extension->name),
+			 "IOT_GATE_EXT_CAN");
+		break;
+	case IOT_GATE_EXT_IED:
+		extension = calloc(1, sizeof(struct extension));
+		snprintf(extension->name, sizeof(extension->name),
+			 "IOT_GATE_EXT_IED");
+		snprintf(extension->overlay, sizeof(extension->overlay),
+			 "imx8mm-cl-iot-gate-ied.dtbo");
+		break;
+	case IOT_GATE_EXT_POE:
+		extension = calloc(1, sizeof(struct extension));
+		snprintf(extension->name, sizeof(extension->name),
+			 "IOT_GATE_EXT_POE");
+		break;
+	case IOT_GATE_EXT_POEV2:
+		extension = calloc(1, sizeof(struct extension));
+		snprintf(extension->name, sizeof(extension->name),
+			 "IOT_GATE_EXT_POEV2");
+		break;
+	default:
+		printf("IOT_GATE-iMX8 extension board: unknown\n");
+		break;
+	}
+
+	if (extension) {
+		snprintf(extension->owner, sizeof(extension->owner),
+			 "Compulab");
+		list_add_tail(&extension->list, extension_list);
+		ret = 1;
+	} else
+		return ret;
+
+	iot_gate_imx8_update_pinmux();
+
+	iot_gate_imx8_update_ext_ied();
+	for (i=0; i<ARRAY_SIZE(iot_gate_imx8_ext_ied_id); i++) {
+		extension = NULL;
+		switch (iot_gate_imx8_ext_ied_id[i]) {
+		case IOT_GATE_IMX8_CARD_ID_EMPTY:
+			break;
+		case IOT_GATE_IMX8_CARD_ID_RS_485:
+			extension = calloc(1, sizeof(struct extension));
+			snprintf(extension->name, sizeof(extension->name),
+				 "IOT_GATE_IMX8_CARD_ID_RS_485");
+			break;
+		case IOT_GATE_IMX8_CARD_ID_RS_232:
+			extension = calloc(1, sizeof(struct extension));
+			snprintf(extension->name, sizeof(extension->name),
+				 "IOT_GATE_IMX8_CARD_ID_RS_232");
+			break;
+		case IOT_GATE_IMX8_CARD_ID_CAN:
+			extension = calloc(1, sizeof(struct extension));
+			snprintf(extension->name, sizeof(extension->name),
+				 "IOT_GATE_IMX8_CARD_ID_CAN");
+			snprintf(extension->overlay, sizeof(extension->overlay),
+				 "imx8mm-cl-iot-gate-ied-can%d.dtbo", i);
+			break;
+		case IOT_GATE_IMX8_CARD_ID_TPM:
+			extension = calloc(1, sizeof(struct extension));
+			snprintf(extension->name, sizeof(extension->name),
+				 "IOT_GATE_IMX8_CARD_ID_TPM");
+			snprintf(extension->overlay, sizeof(extension->overlay),
+				 "imx8mm-cl-iot-gate-ied-tpm%d.dtbo", i);
+			break;
+		case IOT_GATE_IMX8_CARD_ID_CL420:
+			extension = calloc(1, sizeof(struct extension));
+			snprintf(extension->name, sizeof(extension->name),
+				 "IOT_GATE_IMX8_CARD_ID_CL420");
+			snprintf(extension->overlay, sizeof(extension->overlay),
+				 "imx8mm-cl-iot-gate-ied-can%d.dtbo", i);
+			break;
+		case IOT_GATE_IMX8_CARD_ID_DI4O4:
+			extension = calloc(1, sizeof(struct extension));
+			snprintf(extension->name, sizeof(extension->name),
+				 "IOT_GATE_IMX8_CARD_ID_DI4O4");
+			break;
+		default:
+			printf("%s: invalid slot %d card ID: %d\n",
+			       __func__, i, iot_gate_imx8_ext_ied_id[i]);
+			break;
+		}
+		if (extension) {
+			snprintf(extension->owner, sizeof(extension->owner),
+				 "Compulab");
+			snprintf(extension->other, sizeof(extension->other),
+				 "On slot %d", i);
+			list_add_tail(&extension->list, extension_list);
+			ret = ret + 1;
+		}
+	}
+
+        return ret;
+}
+
 int board_late_init(void)
 {
 	if (IS_ENABLED(CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG)) {
