diff --git a/arch/sandbox/dts/test.dts b/arch/sandbox/dts/test.dts
index e95f4631b..14d6983e7 100644
--- a/arch/sandbox/dts/test.dts
+++ b/arch/sandbox/dts/test.dts
@@ -451,6 +451,27 @@
 				reg = <0x16>;
 				#reset-cells = <1>;
 			};
+
+			protocol@17 {
+				reg = <0x17>;
+
+				regulators {
+					#address-cells = <1>;
+					#size-cells = <0>;
+
+					regul0_scmi0: reg@0 {
+						reg = <0>;
+						regulator-name = "sandbox-voltd0";
+						regulator-min-microvolt = <1100000>;
+						regulator-max-microvolt = <3300000>;
+					};
+					regul1_scmi0: reg@1 {
+						reg = <0x1>;
+						regulator-name = "sandbox-voltd1";
+						regulator-min-microvolt = <1800000>;
+					};
+				};
+			};
 		};
 
 		sandbox-scmi-agent@1 {
@@ -1217,6 +1238,8 @@
 		compatible = "sandbox,scmi-devices";
 		clocks = <&clk_scmi0 7>, <&clk_scmi0 3>, <&clk_scmi1 1>;
 		resets = <&reset_scmi0 3>;
+		regul0-supply = <&regul0_scmi0>;
+		regul1-supply = <&regul1_scmi0>;
 	};
 
 	pinctrl {
diff --git a/arch/sandbox/include/asm/scmi_test.h b/arch/sandbox/include/asm/scmi_test.h
index 3e8b0068f..9b7031531 100644
--- a/arch/sandbox/include/asm/scmi_test.h
+++ b/arch/sandbox/include/asm/scmi_test.h
@@ -31,6 +31,18 @@ struct sandbox_scmi_reset {
 	bool asserted;
 };
 
+/**
+ * struct sandbox_scmi_voltd - Simulated voltage regulator exposed by SCMI
+ * @id:		Identifier of the voltage domain used in the SCMI protocol
+ * @enabled:	Regulator state: true if on, false if off
+ * @voltage_uv:	Regulator current voltage in microvoltd (uV)
+ */
+struct sandbox_scmi_voltd {
+	uint id;
+	bool enabled;
+	int voltage_uv;
+};
+
 /**
  * struct sandbox_scmi_agent - Simulated SCMI service seen by SCMI agent
  * @idx:	Identifier for the SCMI agent, its index
@@ -38,6 +50,8 @@ struct sandbox_scmi_reset {
  * @clk_count:	Simulated clocks array size
  * @clk:	Simulated reset domains
  * @clk_count:	Simulated reset domains array size
+ * @voltd:	 Simulated voltage domains (regulators)
+ * @voltd_count: Simulated voltage domains array size
  */
 struct sandbox_scmi_agent {
 	uint idx;
@@ -45,6 +59,8 @@ struct sandbox_scmi_agent {
 	size_t clk_count;
 	struct sandbox_scmi_reset *reset;
 	size_t reset_count;
+	struct sandbox_scmi_voltd *voltd;
+	size_t voltd_count;
 };
 
 /**
@@ -63,12 +79,16 @@ struct sandbox_scmi_service {
  * @clk_count:		Number of clock devices probed
  * @reset:		Array the reset controller devices
  * @reset_count:	Number of reset controller devices probed
+ * @regul:		Array regulator devices
+ * @regul_count:	Number of regulator devices probed
  */
 struct sandbox_scmi_devices {
 	struct clk *clk;
 	size_t clk_count;
 	struct reset_ctl *reset;
 	size_t reset_count;
+	struct udevice **regul;
+	size_t regul_count;
 };
 
 #ifdef CONFIG_SCMI_FIRMWARE
diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index 0c7674efc..790158445 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -214,6 +214,7 @@ CONFIG_DM_REGULATOR_FIXED=y
 CONFIG_REGULATOR_RK8XX=y
 CONFIG_REGULATOR_S5M8767=y
 CONFIG_DM_REGULATOR_SANDBOX=y
+CONFIG_DM_REGULATOR_SCMI=y
 CONFIG_REGULATOR_TPS65090=y
 CONFIG_DM_PWM=y
 CONFIG_PWM_SANDBOX=y
diff --git a/drivers/firmware/scmi/sandbox-scmi_agent.c b/drivers/firmware/scmi/sandbox-scmi_agent.c
index 35de68c75..3eafc49bd 100644
--- a/drivers/firmware/scmi/sandbox-scmi_agent.c
+++ b/drivers/firmware/scmi/sandbox-scmi_agent.c
@@ -19,14 +19,15 @@
  * SCMI protocols embedded in U-Boot. Currently:
  * - SCMI clock protocol: emulate 2 agents each exposing few clocks
  * - SCMI reset protocol: emulate 1 agents each exposing a reset
+ * - SCMI voltage domain protocol: emulate 1 agent exposing 2 regulators
  *
- * Agent #0 simulates 2 clocks and 1 reset domain.
+ * Agent #0 simulates 2 clocks, 1 reset domain and 1 voltage domain.
  * See IDs in scmi0_clk[]/scmi0_reset[] and "sandbox-scmi-agent@0" in test.dts.
  *
  * Agent #1 simulates 1 clock.
  * See IDs in scmi1_clk[] and "sandbox-scmi-agent@1" in test.dts.
  *
- * All clocks are default disabled and reset levels down.
+ * All clocks and regulators are default disabled and reset controller down.
  *
  * This Driver exports sandbox_scmi_service_ct() for the test sequence to
  * get the state of the simulated services (clock state, rate, ...) and
@@ -45,6 +46,11 @@ static struct sandbox_scmi_reset scmi0_reset[] = {
 	{ .id = 3 },
 };
 
+static struct sandbox_scmi_voltd scmi0_voltd[] = {
+	{ .id = 0, .voltage_uv = 3300000 },
+	{ .id = 1, .voltage_uv = 1800000 },
+};
+
 static struct sandbox_scmi_clk scmi1_clk[] = {
 	{ .id = 1, .rate = 44 },
 };
@@ -81,6 +87,13 @@ static void debug_print_agent_state(struct udevice *dev, char *str)
 		agent->reset_count,
 		agent->reset_count ? agent->reset[0].asserted : -1,
 		agent->reset_count > 1 ? agent->reset[1].asserted : -1);
+	dev_dbg(dev, " scmi%u_voltd (%zu): %u/%d, %u/%d, ...\n",
+		agent->idx,
+		agent->voltd_count,
+		agent->voltd_count ? agent->voltd[0].enabled : -1,
+		agent->voltd_count ? agent->voltd[0].voltage_uv : -1,
+		agent->voltd_count ? agent->voltd[1].enabled : -1,
+		agent->voltd_count ? agent->voltd[1].voltage_uv : -1);
 };
 
 static struct sandbox_scmi_clk *get_scmi_clk_state(uint agent_id, uint clock_id)
@@ -123,6 +136,20 @@ static struct sandbox_scmi_reset *get_scmi_reset_state(uint agent_id,
 	return NULL;
 }
 
+static struct sandbox_scmi_voltd *get_scmi_voltd_state(uint agent_id,
+						       uint domain_id)
+{
+	size_t n;
+
+	if (agent_id == 0) {
+		for (n = 0; n < ARRAY_SIZE(scmi0_voltd); n++)
+			if (scmi0_voltd[n].id == domain_id)
+				return scmi0_voltd + n;
+	}
+
+	return NULL;
+}
+
 /*
  * Sandbox SCMI agent ops
  */
@@ -290,6 +317,160 @@ static int sandbox_scmi_rd_reset(struct udevice *dev, struct scmi_msg *msg)
 	return 0;
 }
 
+static int sandbox_scmi_voltd_attribs(struct udevice *dev, struct scmi_msg *msg)
+{
+	struct sandbox_scmi_agent *agent = dev_get_priv(dev);
+	struct scmi_voltd_attr_in *in = NULL;
+	struct scmi_voltd_attr_out *out = NULL;
+	struct sandbox_scmi_voltd *voltd_state = NULL;
+
+	if (!msg->in_msg || msg->in_msg_sz < sizeof(*in) ||
+	    !msg->out_msg || msg->out_msg_sz < sizeof(*out))
+		return -EINVAL;
+
+	in = (struct scmi_voltd_attr_in *)msg->in_msg;
+	out = (struct scmi_voltd_attr_out *)msg->out_msg;
+
+	voltd_state = get_scmi_voltd_state(agent->idx, in->domain_id);
+	if (!voltd_state) {
+		dev_err(dev, "Unexpected domain ID %u\n", in->domain_id);
+
+		out->status = SCMI_NOT_FOUND;
+	} else {
+		memset(out, 0, sizeof(*out));
+		snprintf(out->name, sizeof(out->name), "regu%u", in->domain_id);
+
+		out->status = SCMI_SUCCESS;
+	}
+
+	return 0;
+}
+
+static int sandbox_scmi_voltd_config_set(struct udevice *dev,
+					 struct scmi_msg *msg)
+{
+	struct sandbox_scmi_agent *agent = dev_get_priv(dev);
+	struct scmi_voltd_config_set_in *in = NULL;
+	struct scmi_voltd_config_set_out *out = NULL;
+	struct sandbox_scmi_voltd *voltd_state = NULL;
+
+	if (!msg->in_msg || msg->in_msg_sz < sizeof(*in) ||
+	    !msg->out_msg || msg->out_msg_sz < sizeof(*out))
+		return -EINVAL;
+
+	in = (struct scmi_voltd_config_set_in *)msg->in_msg;
+	out = (struct scmi_voltd_config_set_out *)msg->out_msg;
+
+	voltd_state = get_scmi_voltd_state(agent->idx, in->domain_id);
+	if (!voltd_state) {
+		dev_err(dev, "Unexpected domain ID %u\n", in->domain_id);
+
+		out->status = SCMI_NOT_FOUND;
+	} else if (in->config & ~SCMI_VOLTD_CONFIG_MASK) {
+		dev_err(dev, "Invalid config value 0x%x\n", in->config);
+
+		out->status = SCMI_INVALID_PARAMETERS;
+	} else if (in->config != SCMI_VOLTD_CONFIG_ON &&
+		   in->config != SCMI_VOLTD_CONFIG_OFF) {
+		dev_err(dev, "Unexpected custom value 0x%x\n", in->config);
+
+		out->status = SCMI_INVALID_PARAMETERS;
+	} else {
+		voltd_state->enabled = in->config == SCMI_VOLTD_CONFIG_ON;
+		out->status = SCMI_SUCCESS;
+	}
+
+	return 0;
+}
+
+static int sandbox_scmi_voltd_config_get(struct udevice *dev,
+					 struct scmi_msg *msg)
+{
+	struct sandbox_scmi_agent *agent = dev_get_priv(dev);
+	struct scmi_voltd_config_get_in *in = NULL;
+	struct scmi_voltd_config_get_out *out = NULL;
+	struct sandbox_scmi_voltd *voltd_state = NULL;
+
+	if (!msg->in_msg || msg->in_msg_sz < sizeof(*in) ||
+	    !msg->out_msg || msg->out_msg_sz < sizeof(*out))
+		return -EINVAL;
+
+	in = (struct scmi_voltd_config_get_in *)msg->in_msg;
+	out = (struct scmi_voltd_config_get_out *)msg->out_msg;
+
+	voltd_state = get_scmi_voltd_state(agent->idx, in->domain_id);
+	if (!voltd_state) {
+		dev_err(dev, "Unexpected domain ID %u\n", in->domain_id);
+
+		out->status = SCMI_NOT_FOUND;
+	} else {
+		if (voltd_state->enabled)
+			out->config = SCMI_VOLTD_CONFIG_ON;
+		else
+			out->config = SCMI_VOLTD_CONFIG_OFF;
+
+		out->status = SCMI_SUCCESS;
+	}
+
+	return 0;
+}
+
+static int sandbox_scmi_voltd_level_set(struct udevice *dev,
+					 struct scmi_msg *msg)
+{
+	struct sandbox_scmi_agent *agent = dev_get_priv(dev);
+	struct scmi_voltd_level_set_in *in = NULL;
+	struct scmi_voltd_level_set_out *out = NULL;
+	struct sandbox_scmi_voltd *voltd_state = NULL;
+
+	if (!msg->in_msg || msg->in_msg_sz < sizeof(*in) ||
+	    !msg->out_msg || msg->out_msg_sz < sizeof(*out))
+		return -EINVAL;
+
+	in = (struct scmi_voltd_level_set_in *)msg->in_msg;
+	out = (struct scmi_voltd_level_set_out *)msg->out_msg;
+
+	voltd_state = get_scmi_voltd_state(agent->idx, in->domain_id);
+	if (!voltd_state) {
+		dev_err(dev, "Unexpected domain ID %u\n", in->domain_id);
+
+		out->status = SCMI_NOT_FOUND;
+	} else {
+		voltd_state->voltage_uv = in->voltage_level;
+		out->status = SCMI_SUCCESS;
+	}
+
+	return 0;
+}
+
+static int sandbox_scmi_voltd_level_get(struct udevice *dev,
+					struct scmi_msg *msg)
+{
+	struct sandbox_scmi_agent *agent = dev_get_priv(dev);
+	struct scmi_voltd_level_get_in *in = NULL;
+	struct scmi_voltd_level_get_out *out = NULL;
+	struct sandbox_scmi_voltd *voltd_state = NULL;
+
+	if (!msg->in_msg || msg->in_msg_sz < sizeof(*in) ||
+	    !msg->out_msg || msg->out_msg_sz < sizeof(*out))
+		return -EINVAL;
+
+	in = (struct scmi_voltd_level_get_in *)msg->in_msg;
+	out = (struct scmi_voltd_level_get_out *)msg->out_msg;
+
+	voltd_state = get_scmi_voltd_state(agent->idx, in->domain_id);
+	if (!voltd_state) {
+		dev_err(dev, "Unexpected domain ID %u\n", in->domain_id);
+
+		out->status = SCMI_NOT_FOUND;
+	} else {
+		out->voltage_level = voltd_state->voltage_uv;
+		out->status = SCMI_SUCCESS;
+	}
+
+	return 0;
+}
+
 static int sandbox_scmi_test_process_msg(struct udevice *dev,
 					 struct scmi_msg *msg)
 {
@@ -316,6 +497,22 @@ static int sandbox_scmi_test_process_msg(struct udevice *dev,
 			break;
 		}
 		break;
+	case SCMI_PROTOCOL_ID_VOLTAGE_DOMAIN:
+		switch (msg->message_id) {
+		case SCMI_VOLTAGE_DOMAIN_ATTRIBUTES:
+			return sandbox_scmi_voltd_attribs(dev, msg);
+		case SCMI_VOLTAGE_DOMAIN_CONFIG_SET:
+			return sandbox_scmi_voltd_config_set(dev, msg);
+		case SCMI_VOLTAGE_DOMAIN_CONFIG_GET:
+			return sandbox_scmi_voltd_config_get(dev, msg);
+		case SCMI_VOLTAGE_DOMAIN_LEVEL_SET:
+			return sandbox_scmi_voltd_level_set(dev, msg);
+		case SCMI_VOLTAGE_DOMAIN_LEVEL_GET:
+			return sandbox_scmi_voltd_level_get(dev, msg);
+		default:
+			break;
+		}
+		break;
 	case SCMI_PROTOCOL_ID_BASE:
 	case SCMI_PROTOCOL_ID_POWER_DOMAIN:
 	case SCMI_PROTOCOL_ID_SYSTEM:
@@ -367,6 +564,8 @@ static int sandbox_scmi_test_probe(struct udevice *dev)
 			.clk_count = ARRAY_SIZE(scmi0_clk),
 			.reset = scmi0_reset,
 			.reset_count = ARRAY_SIZE(scmi0_reset),
+			.voltd = scmi0_voltd,
+			.voltd_count = ARRAY_SIZE(scmi0_voltd),
 		};
 		break;
 	case '1':
diff --git a/drivers/firmware/scmi/sandbox-scmi_devices.c b/drivers/firmware/scmi/sandbox-scmi_devices.c
index 1a6fafbf5..aab5782fd 100644
--- a/drivers/firmware/scmi/sandbox-scmi_devices.c
+++ b/drivers/firmware/scmi/sandbox-scmi_devices.c
@@ -1,16 +1,18 @@
 // SPDX-License-Identifier: GPL-2.0
 /*
- * Copyright (C) 2020, Linaro Limited
+ * Copyright (C) 2020-2021, Linaro Limited
  */
 
 #include <common.h>
 #include <clk.h>
 #include <dm.h>
+#include <log.h>
 #include <malloc.h>
 #include <reset.h>
 #include <asm/io.h>
 #include <asm/scmi_test.h>
 #include <dm/device_compat.h>
+#include <power/regulator.h>
 
 /*
  * Simulate to some extent a SCMI exchange.
@@ -21,16 +23,19 @@
 
 #define SCMI_TEST_DEVICES_CLK_COUNT		3
 #define SCMI_TEST_DEVICES_RD_COUNT		1
+#define SCMI_TEST_DEVICES_VOLTD_COUNT		2
 
 /*
  * struct sandbox_scmi_device_priv - Storage for device handles used by test
  * @clk:		Array of clock instances used by tests
  * @reset_clt:		Array of the reset controller instances used by tests
+ * @regulators:		Array of regulator device references used by the tests
  * @devices:		Resources exposed by sandbox_scmi_devices_ctx()
  */
 struct sandbox_scmi_device_priv {
 	struct clk clk[SCMI_TEST_DEVICES_CLK_COUNT];
 	struct reset_ctl reset_ctl[SCMI_TEST_DEVICES_RD_COUNT];
+	struct udevice *regulators[SCMI_TEST_DEVICES_VOLTD_COUNT];
 	struct sandbox_scmi_devices devices;
 };
 
@@ -74,6 +79,8 @@ static int sandbox_scmi_devices_probe(struct udevice *dev)
 		.clk_count = SCMI_TEST_DEVICES_CLK_COUNT,
 		.reset = priv->reset_ctl,
 		.reset_count = SCMI_TEST_DEVICES_RD_COUNT,
+		.regul = priv->regulators,
+		.regul_count = SCMI_TEST_DEVICES_VOLTD_COUNT,
 	};
 
 	for (n = 0; n < SCMI_TEST_DEVICES_CLK_COUNT; n++) {
@@ -92,8 +99,24 @@ static int sandbox_scmi_devices_probe(struct udevice *dev)
 		}
 	}
 
+	for (n = 0; n < SCMI_TEST_DEVICES_VOLTD_COUNT; n++) {
+		char name[32];
+
+		ret = snprintf(name, sizeof(name), "regul%zu-supply", n);
+		assert(ret >= 0 && ret < sizeof(name));
+
+		ret = device_get_supply_regulator(dev, name,
+						  priv->devices.regul + n);
+		if (ret) {
+			dev_err(dev, "%s: Failed on voltd %zu\n", __func__, n);
+			goto err_regul;
+		}
+	}
+
 	return 0;
 
+err_regul:
+	n = SCMI_TEST_DEVICES_RD_COUNT;
 err_reset:
 	for (; n > 0; n--)
 		reset_free(priv->devices.reset + n - 1);
diff --git a/test/dm/scmi.c b/test/dm/scmi.c
index be60b44b3..f21a3ff97 100644
--- a/test/dm/scmi.c
+++ b/test/dm/scmi.c
@@ -20,6 +20,7 @@
 #include <dm/device-internal.h>
 #include <dm/test.h>
 #include <linux/kconfig.h>
+#include <power/regulator.h>
 #include <test/ut.h>
 
 static int ut_assert_scmi_state_preprobe(struct unit_test_state *uts)
@@ -47,6 +48,8 @@ static int ut_assert_scmi_state_postprobe(struct unit_test_state *uts,
 		ut_asserteq(3, scmi_devices->clk_count);
 	if (IS_ENABLED(CONFIG_RESET_SCMI))
 		ut_asserteq(1, scmi_devices->reset_count);
+	if (IS_ENABLED(CONFIG_DM_REGULATOR_SCMI))
+		ut_asserteq(2, scmi_devices->regul_count);
 
 	/* State of the simulated SCMI server exposed */
 	scmi_ctx = sandbox_scmi_service_ctx();
@@ -58,6 +61,10 @@ static int ut_assert_scmi_state_postprobe(struct unit_test_state *uts,
 	ut_assertnonnull(scmi_ctx->agent[0]->clk);
 	ut_asserteq(1, scmi_ctx->agent[0]->reset_count);
 	ut_assertnonnull(scmi_ctx->agent[0]->reset);
+	if (IS_ENABLED(CONFIG_DM_REGULATOR_SCMI)) {
+		ut_asserteq(2, scmi_ctx->agent[0]->voltd_count);
+		ut_assertnonnull(scmi_ctx->agent[0]->voltd);
+	}
 
 	ut_assertnonnull(scmi_ctx->agent[1]);
 	ut_assertnonnull(scmi_ctx->agent[1]->clk);
@@ -201,3 +208,60 @@ static int dm_test_scmi_resets(struct unit_test_state *uts)
 }
 
 DM_TEST(dm_test_scmi_resets, UT_TESTF_SCAN_FDT);
+
+static int dm_test_scmi_voltage_domains(struct unit_test_state *uts)
+{
+	struct sandbox_scmi_devices *scmi_devices;
+	struct sandbox_scmi_service *scmi_ctx;
+	struct sandbox_scmi_voltd *sandbox_voltd;
+	struct dm_regulator_uclass_plat *uc_pdata;
+	struct udevice *dev;
+	struct udevice *regul_dev;
+
+	if (!IS_ENABLED(CONFIG_DM_REGULATOR_SCMI))
+		return 0;
+
+	ut_assertok(load_sandbox_scmi_test_devices(uts, &dev));
+
+	scmi_devices = sandbox_scmi_devices_ctx(dev);
+	scmi_ctx = sandbox_scmi_service_ctx();
+
+	/* Set/Get an SCMI voltage domain level */
+	sandbox_voltd = &scmi_ctx->agent[0]->voltd[0];
+	regul_dev = scmi_devices->regul[0];
+	ut_assert(regul_dev);
+
+	uc_pdata = dev_get_uclass_plat(regul_dev);
+	ut_assert(uc_pdata);
+
+	ut_assertok(regulator_set_value(regul_dev, uc_pdata->min_uV));
+	ut_asserteq(sandbox_voltd->voltage_uv, uc_pdata->min_uV);
+
+	ut_assert(regulator_get_value(regul_dev) == uc_pdata->min_uV);
+
+	ut_assertok(regulator_set_value(regul_dev, uc_pdata->max_uV));
+	ut_asserteq(sandbox_voltd->voltage_uv, uc_pdata->max_uV);
+
+	ut_assert(regulator_get_value(regul_dev) == uc_pdata->max_uV);
+
+	/* Enable/disable SCMI voltage domains */
+	ut_assertok(regulator_set_enable(scmi_devices->regul[0], false));
+	ut_assertok(regulator_set_enable(scmi_devices->regul[1], false));
+	ut_assert(!scmi_ctx->agent[0]->voltd[0].enabled);
+	ut_assert(!scmi_ctx->agent[0]->voltd[1].enabled);
+
+	ut_assertok(regulator_set_enable(scmi_devices->regul[0], true));
+	ut_assert(scmi_ctx->agent[0]->voltd[0].enabled);
+	ut_assert(!scmi_ctx->agent[0]->voltd[1].enabled);
+
+	ut_assertok(regulator_set_enable(scmi_devices->regul[1], true));
+	ut_assert(scmi_ctx->agent[0]->voltd[0].enabled);
+	ut_assert(scmi_ctx->agent[0]->voltd[1].enabled);
+
+	ut_assertok(regulator_set_enable(scmi_devices->regul[0], false));
+	ut_assert(!scmi_ctx->agent[0]->voltd[0].enabled);
+	ut_assert(scmi_ctx->agent[0]->voltd[1].enabled);
+
+	return release_sandbox_scmi_test_devices(uts, dev);
+}
+DM_TEST(dm_test_scmi_voltage_domains, UT_TESTF_SCAN_FDT);
