diff --git a/services/std_svc/spm/spci.c b/services/std_svc/spm/spci.c
index 1544ae1..41b0b00 100644
--- a/services/std_svc/spm/spci.c
+++ b/services/std_svc/spm/spci.c
@@ -108,6 +108,20 @@
 }
 
 /*******************************************************************************
+ * Returns a unique token for a Secure Service request.
+ ******************************************************************************/
+static uint32_t spci_create_token_value(void)
+{
+	/*
+	 * Trivial implementation that relies on the fact that any response will
+	 * be read before 2^32 more service requests have been done.
+	 */
+	static uint32_t token_count;
+
+	return token_count++;
+}
+
+/*******************************************************************************
  * This function looks for a Secure Partition that has a Secure Service
  * identified by the given UUID. It returns a handle that the client can use to
  * access the service, and an SPCI_*** error code.
@@ -364,6 +378,290 @@
 }
 
 /*******************************************************************************
+ * This function requests a Secure Service from a given handle and client ID.
+ ******************************************************************************/
+static uint64_t spci_service_request_start(void *handle,
+			uint32_t smc_fid, u_register_t x1, u_register_t x2,
+			u_register_t x3, u_register_t x4, u_register_t x5,
+			u_register_t x6, u_register_t x7)
+{
+	spci_handle_t *handle_info;
+	sp_context_t *sp_ctx;
+	cpu_context_t *cpu_ctx;
+	uint16_t request_handle, client_id;
+	uint32_t token;
+
+	/* Get handle array lock */
+	spin_lock(&spci_handles_lock);
+
+	/* Get pointer to struct of this open handle and client ID. */
+	request_handle = (x7 >> 16U) & 0x0000FFFFU;
+	client_id = x7 & 0x0000FFFFU;
+
+	handle_info = spci_handle_info_get(request_handle, client_id);
+	if (handle_info == NULL) {
+		spin_unlock(&spci_handles_lock);
+
+		WARN("SPCI_SERVICE_TUN_REQUEST_START: Not found.\n"
+		     "  Handle 0x%04x. Client ID 0x%04x\n", request_handle,
+		     client_id);
+
+		SMC_RET1(handle, SPCI_INVALID_PARAMETER);
+	}
+
+	/* Get pointer to the Secure Partition that handles the service */
+	sp_ctx = handle_info->sp_ctx;
+	assert(sp_ctx != NULL);
+	cpu_ctx = &(sp_ctx->cpu_ctx);
+
+	/* Prevent this handle from being closed */
+	handle_info->num_active_requests += 1;
+
+	spm_sp_request_increase(sp_ctx);
+
+	/* Create new token for this request */
+	token = spci_create_token_value();
+
+	/* Release handle lock */
+	spin_unlock(&spci_handles_lock);
+
+	/* Pass arguments to the Secure Partition */
+	struct sprt_queue_entry_message message = {
+		.type = SPRT_MSG_TYPE_SERVICE_TUN_REQUEST,
+		.client_id = client_id,
+		.service_handle = request_handle,
+		.session_id = x6,
+		.token = token,
+		.args = {smc_fid, x1, x2, x3, x4, x5}
+	};
+
+	spin_lock(&(sp_ctx->spm_sp_buffer_lock));
+	int rc = sprt_push_message((void *)sp_ctx->spm_sp_buffer_base, &message,
+				   SPRT_QUEUE_NUM_NON_BLOCKING);
+	spin_unlock(&(sp_ctx->spm_sp_buffer_lock));
+	if (rc != 0) {
+		WARN("SPCI_SERVICE_TUN_REQUEST_START: SPRT queue full.\n"
+		     "  Handle 0x%04x. Client ID 0x%04x\n", request_handle,
+		     client_id);
+		SMC_RET1(handle, SPCI_NO_MEMORY);
+	}
+
+	/* Try to enter the partition. If it's not possible, simply return. */
+	if (sp_state_try_switch(sp_ctx, SP_STATE_IDLE, SP_STATE_BUSY) != 0) {
+		SMC_RET2(handle, SPCI_SUCCESS, token);
+	}
+
+	/* Save the Normal world context */
+	cm_el1_sysregs_context_save(NON_SECURE);
+
+	/* Jump to the Secure Partition. */
+	uint64_t ret = spm_sp_synchronous_entry(sp_ctx);
+
+	/* Verify returned values */
+	if (ret == SPRT_PUT_RESPONSE_AARCH64) {
+		uint32_t token;
+		uint64_t rx1, rx2, rx3, x6;
+
+		token = read_ctx_reg(get_gpregs_ctx(cpu_ctx), CTX_GPREG_X1);
+		rx1 = read_ctx_reg(get_gpregs_ctx(cpu_ctx), CTX_GPREG_X3);
+		rx2 = read_ctx_reg(get_gpregs_ctx(cpu_ctx), CTX_GPREG_X4);
+		rx3 = read_ctx_reg(get_gpregs_ctx(cpu_ctx), CTX_GPREG_X5);
+		x6 = read_ctx_reg(get_gpregs_ctx(cpu_ctx), CTX_GPREG_X6);
+
+		uint16_t client_id = x6 & 0xFFFFU;
+		uint16_t service_handle = x6 >> 16;
+
+		int rc = spm_response_add(client_id, service_handle, token,
+					  rx1, rx2, rx3);
+		if (rc != 0) {
+			/*
+			 * This is error fatal because we can't return to the SP
+			 * from this SMC. The SP has crashed.
+			 */
+			panic();
+		}
+	} else if (ret != SPRT_YIELD_AARCH64) {
+		ERROR("SPM: %s: Unexpected x0 value 0x%llx\n", __func__, ret);
+		panic();
+	}
+
+	/* Flag Secure Partition as idle. */
+	assert(sp_ctx->state == SP_STATE_BUSY);
+	sp_state_set(sp_ctx, SP_STATE_IDLE);
+
+	/* Restore non-secure state */
+	cm_el1_sysregs_context_restore(NON_SECURE);
+	cm_set_next_eret_context(NON_SECURE);
+
+	SMC_RET2(handle, SPCI_SUCCESS, token);
+}
+
+/*******************************************************************************
+ * This function returns the response of a Secure Service given a handle, a
+ * client ID and a token. If not available, it will schedule a Secure Partition
+ * and give it CPU time.
+ ******************************************************************************/
+static uint64_t spci_service_request_resume(void *handle, u_register_t x1,
+					    u_register_t x7)
+{
+	int rc;
+	u_register_t rx1 = 0, rx2 = 0, rx3 = 0;
+	spci_handle_t *handle_info;
+	sp_context_t *sp_ctx;
+	cpu_context_t *cpu_ctx;
+	uint32_t token = (uint32_t) x1;
+	uint16_t client_id = x7 & 0x0000FFFF;
+	uint16_t service_handle = (x7 >> 16) & 0x0000FFFF;
+
+	/* Get pointer to struct of this open handle and client ID. */
+	spin_lock(&spci_handles_lock);
+
+	handle_info = spci_handle_info_get(service_handle, client_id);
+	if (handle_info == NULL) {
+		spin_unlock(&spci_handles_lock);
+		WARN("SPCI_SERVICE_REQUEST_RESUME: Not found.\n"
+		     "Handle 0x%04x. Client ID 0x%04x, Token 0x%08x.\n",
+		     client_id, service_handle, token);
+
+		SMC_RET1(handle, SPCI_INVALID_PARAMETER);
+	}
+
+	/* Get pointer to the Secure Partition that handles the service */
+	sp_ctx = handle_info->sp_ctx;
+	assert(sp_ctx != NULL);
+	cpu_ctx = &(sp_ctx->cpu_ctx);
+
+	spin_unlock(&spci_handles_lock);
+
+	/* Look for a valid response in the global queue */
+	rc = spm_response_get(client_id, service_handle, token,
+			      &rx1, &rx2, &rx3);
+	if (rc == 0) {
+		/* Decrease request count */
+		spin_lock(&spci_handles_lock);
+		handle_info->num_active_requests -= 1;
+		spin_unlock(&spci_handles_lock);
+		spm_sp_request_decrease(sp_ctx);
+
+		SMC_RET4(handle, SPCI_SUCCESS, rx1, rx2, rx3);
+	}
+
+	/* Try to enter the partition. If it's not possible, simply return. */
+	if (sp_state_try_switch(sp_ctx, SP_STATE_IDLE, SP_STATE_BUSY) != 0) {
+		SMC_RET1(handle, SPCI_QUEUED);
+	}
+
+	/* Save the Normal world context */
+	cm_el1_sysregs_context_save(NON_SECURE);
+
+	/* Jump to the Secure Partition. */
+	uint64_t ret = spm_sp_synchronous_entry(sp_ctx);
+
+	/* Verify returned values */
+	if (ret == SPRT_PUT_RESPONSE_AARCH64) {
+		uint32_t token;
+		uint64_t rx1, rx2, rx3, x6;
+
+		token = read_ctx_reg(get_gpregs_ctx(cpu_ctx), CTX_GPREG_X1);
+		rx1 = read_ctx_reg(get_gpregs_ctx(cpu_ctx), CTX_GPREG_X3);
+		rx2 = read_ctx_reg(get_gpregs_ctx(cpu_ctx), CTX_GPREG_X4);
+		rx3 = read_ctx_reg(get_gpregs_ctx(cpu_ctx), CTX_GPREG_X5);
+		x6 = read_ctx_reg(get_gpregs_ctx(cpu_ctx), CTX_GPREG_X6);
+
+		uint16_t client_id = x6 & 0xFFFFU;
+		uint16_t service_handle = x6 >> 16;
+
+		int rc = spm_response_add(client_id, service_handle, token,
+					  rx1, rx2, rx3);
+		if (rc != 0) {
+			/*
+			 * This is error fatal because we can't return to the SP
+			 * from this SMC. The SP has crashed.
+			 */
+			panic();
+		}
+	} else if (ret != SPRT_YIELD_AARCH64) {
+		ERROR("SPM: %s: Unexpected x0 value 0x%llx\n", __func__, ret);
+		panic();
+	}
+
+	/* Flag Secure Partition as idle. */
+	assert(sp_ctx->state == SP_STATE_BUSY);
+	sp_state_set(sp_ctx, SP_STATE_IDLE);
+
+	/* Restore non-secure state */
+	cm_el1_sysregs_context_restore(NON_SECURE);
+	cm_set_next_eret_context(NON_SECURE);
+
+	/* Look for a valid response in the global queue */
+	rc = spm_response_get(client_id, service_handle, token,
+			      &rx1, &rx2, &rx3);
+	if (rc != 0) {
+		SMC_RET1(handle, SPCI_QUEUED);
+	}
+
+	/* Decrease request count */
+	spin_lock(&spci_handles_lock);
+	handle_info->num_active_requests -= 1;
+	spin_unlock(&spci_handles_lock);
+	spm_sp_request_decrease(sp_ctx);
+
+	/* Return response */
+	SMC_RET4(handle, SPCI_SUCCESS, rx1, rx2, rx3);
+}
+
+/*******************************************************************************
+ * This function returns the response of a Secure Service given a handle, a
+ * client ID and a token.
+ ******************************************************************************/
+static uint64_t spci_service_get_response(void *handle, u_register_t x1,
+					    u_register_t x7)
+
+{
+	int rc;
+	u_register_t rx1 = 0, rx2 = 0, rx3 = 0;
+	spci_handle_t *handle_info;
+	uint32_t token = (uint32_t) x1;
+	uint16_t client_id = x7 & 0x0000FFFF;
+	uint16_t service_handle = (x7 >> 16) & 0x0000FFFF;
+
+	/* Get pointer to struct of this open handle and client ID. */
+
+	spin_lock(&spci_handles_lock);
+
+	handle_info = spci_handle_info_get(service_handle, client_id);
+	if (handle_info == NULL) {
+		spin_unlock(&spci_handles_lock);
+		WARN("SPCI_SERVICE_GET_RESPONSE: Not found.\n"
+		     "Handle 0x%04x. Client ID 0x%04x, Token 0x%08x.\n",
+		     client_id, service_handle, token);
+
+		SMC_RET1(handle, SPCI_INVALID_PARAMETER);
+	}
+
+	spin_unlock(&spci_handles_lock);
+
+	/* Look for a valid response in the global queue */
+	rc = spm_response_get(client_id, service_handle, token,
+			      &rx1, &rx2, &rx3);
+
+	if (rc != 0) {
+		SMC_RET1(handle, SPCI_QUEUED);
+	}
+
+	/* Decrease request count */
+	spin_lock(&spci_handles_lock);
+	handle_info->num_active_requests -= 1;
+	sp_context_t *sp_ctx;
+	sp_ctx = handle_info->sp_ctx;
+	spin_unlock(&spci_handles_lock);
+	spm_sp_request_decrease(sp_ctx);
+
+	/* Return response */
+	SMC_RET4(handle, SPCI_SUCCESS, rx1, rx2, rx3);
+}
+
+/*******************************************************************************
  * This function handles all SMCs in the range reserved for SPCI.
  ******************************************************************************/
 uint64_t spci_smc_handler(uint32_t smc_fid, uint64_t x1, uint64_t x2,
@@ -416,6 +714,23 @@
 					smc_fid, x1, x2, x3, x4, x5, x6, x7);
 		}
 
+		case SPCI_FID_SERVICE_REQUEST_START:
+		{
+			uint64_t x5 = SMC_GET_GP(handle, CTX_GPREG_X5);
+			uint64_t x6 = SMC_GET_GP(handle, CTX_GPREG_X6);
+			uint64_t x7 = SMC_GET_GP(handle, CTX_GPREG_X7);
+
+			return spci_service_request_start(handle,
+					smc_fid, x1, x2, x3, x4, x5, x6, x7);
+		}
+
+		case SPCI_FID_SERVICE_GET_RESPONSE:
+		{
+			uint64_t x7 = SMC_GET_GP(handle, CTX_GPREG_X7);
+
+			return spci_service_get_response(handle, x1, x7);
+		}
+
 		default:
 			break;
 		}
@@ -424,6 +739,20 @@
 
 		/* Tunneled calls */
 
+		spci_fid = (smc_fid >> SPCI_FID_TUN_SHIFT) & SPCI_FID_TUN_MASK;
+
+		switch (spci_fid) {
+
+		case SPCI_FID_SERVICE_REQUEST_RESUME:
+		{
+			uint64_t x7 = SMC_GET_GP(handle, CTX_GPREG_X7);
+
+			return spci_service_request_resume(handle, x1, x7);
+		}
+
+		default:
+			break;
+		}
 	}
 
 	WARN("SPCI: Unsupported call 0x%08x\n", smc_fid);