spd: trusty: Add FFA_RX_RELEASE

Bug: 284057071
Change-Id: I15f15bb02aca563b3c106f0941cfd9a341602d56

services/spd/trusty/shared-mem-smcall.c

@@ -912,6 +912,18 @@ static int trusty_ffa_id_get(u_register_t flags, u_register_t *idp)
 	return 0;
 }
 
+/**
+ * trusty_ffa_rx_release - FFA_RX_RELEASE implementation.
+ * @client:             Client state.
+ *
+ * Return: 0 on success, error code on failure.
+ */
+static long trusty_ffa_rx_release(struct trusty_shmem_client_state *client)
+{
+	/* Trusty SPD doesn't track mailbox state */
+	return 0;
+}
+
 /**
  * trusty_ffa_version - FFA_VERSION implementation.
  * @client:     Client state.
@@ -1090,6 +1102,10 @@ uintptr_t spmd_ffa_smc_handler(uint32_t smc_fid,
 		ret = trusty_ffa_rxtx_unmap(client, w1);
 		break;
 
+	case FFA_RX_RELEASE:
+		ret = trusty_ffa_rx_release(client);
+		break;
+
 	case FFA_ID_GET:
 		ret = trusty_ffa_id_get(flags, &ret_reg2);
 		break;