--- /dev/null
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2020-2021 Linaro Limited.
+ */
+
+#define LOG_CATEGORY UCLASS_SCMI_AGENT
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <scmi_agent.h>
+#include <scmi_agent-uclass.h>
+#include <string.h>
+#include <tee.h>
+#include <asm/types.h>
+#include <dm/device_compat.h>
+#include <dm/devres.h>
+#include <linux/arm-smccc.h>
+#include <linux/bug.h>
+#include <linux/compat.h>
+
+#include "smt.h"
+
+#define SCMI_SHM_SIZE 128
+
+/**
+ * struct scmi_optee_channel - Description of an SCMI OP-TEE transport
+ * @channel_id: Channel identifier
+ * @smt: Shared memory buffer with synchronisation protocol
+ * @dyn_shm: True if using dynamically allocated shared memory
+ */
+struct scmi_optee_channel {
+ unsigned int channel_id;
+ struct scmi_smt smt;
+ bool dyn_shm;
+};
+
+/**
+ * struct channel_session - Aggreates SCMI service session context references
+ * @tee: OP-TEE device to invoke
+ * @tee_session: OP-TEE session identifier
+ * @tee_shm: Dynamically allocated OP-TEE shared memory, or NULL
+ * @channel_hdl: Channel handle provided by OP-TEE SCMI service
+ */
+struct channel_session {
+ struct udevice *tee;
+ u32 tee_session;
+ struct tee_shm *tee_shm;
+ u32 channel_hdl;
+};
+
+#define TA_SCMI_UUID { 0xa8cfe406, 0xd4f5, 0x4a2e, \
+ { 0x9f, 0x8d, 0xa2, 0x5d, 0xc7, 0x54, 0xc0, 0x99 } }
+
+enum optee_smci_pta_cmd {
+ /*
+ * PTA_SCMI_CMD_CAPABILITIES - Get channel capabilities
+ *
+ * [out] value[0].a: Capability bit mask (enum pta_scmi_caps)
+ * [out] value[0].b: Extended capabilities or 0
+ */
+ PTA_SCMI_CMD_CAPABILITIES = 0,
+
+ /*
+ * PTA_SCMI_CMD_PROCESS_SMT_CHANNEL - Process SCMI message in SMT buffer
+ *
+ * [in] value[0].a: Channel handle
+ *
+ * Shared memory used for SCMI message/response exhange is expected
+ * already identified and bound to channel handle in both SCMI agent
+ * and SCMI server (OP-TEE) parts.
+ * The memory uses SMT header to carry SCMI meta-data (protocol ID and
+ * protocol message ID).
+ */
+ PTA_SCMI_CMD_PROCESS_SMT_CHANNEL = 1,
+
+ /*
+ * PTA_SCMI_CMD_PROCESS_SMT_CHANNEL_MESSAGE - Process SMT/SCMI message
+ *
+ * [in] value[0].a: Channel handle
+ * [in/out] memref[1]: Message/response buffer (SMT and SCMI payload)
+ *
+ * Shared memory used for SCMI message/response is a SMT buffer
+ * referenced by param[1]. It shall be 128 bytes large to fit response
+ * payload whatever message playload size.
+ * The memory uses SMT header to carry SCMI meta-data (protocol ID and
+ * protocol message ID).
+ */
+ PTA_SCMI_CMD_PROCESS_SMT_CHANNEL_MESSAGE = 2,
+
+ /*
+ * PTA_SCMI_CMD_GET_CHANNEL - Get channel handle
+ *
+ * SCMI shm information are 0 if agent expects to use OP-TEE regular SHM
+ *
+ * [in] value[0].a: Channel identifier
+ * [out] value[0].a: Returned channel handle
+ * [in] value[0].b: Requested capabilities mask (enum pta_scmi_caps)
+ */
+ PTA_SCMI_CMD_GET_CHANNEL = 3,
+};
+
+/*
+ * OP-TEE SCMI service capabilities bit flags (32bit)
+ *
+ * PTA_SCMI_CAPS_SMT_HEADER
+ * When set, OP-TEE supports command using SMT header protocol (SCMI shmem) in
+ * shared memory buffers to carry SCMI protocol synchronisation information.
+ */
+#define PTA_SCMI_CAPS_NONE 0
+#define PTA_SCMI_CAPS_SMT_HEADER BIT(0)
+
+static int open_channel(struct udevice *dev, struct channel_session *sess)
+{
+ const struct tee_optee_ta_uuid uuid = TA_SCMI_UUID;
+ struct scmi_optee_channel *chan = dev_get_plat(dev);
+ struct tee_open_session_arg sess_arg = { };
+ struct tee_invoke_arg cmd_arg = { };
+ struct tee_param param[1] = { };
+ int ret;
+
+ memset(sess, 0, sizeof(sess));
+
+ sess->tee = tee_find_device(NULL, NULL, NULL, NULL);
+ if (!sess->tee)
+ return -ENODEV;
+
+ sess_arg.clnt_login = TEE_LOGIN_REE_KERNEL;
+ tee_optee_ta_uuid_to_octets(sess_arg.uuid, &uuid);
+
+ ret = tee_open_session(sess->tee, &sess_arg, 0, NULL);
+ if (ret) {
+ dev_err(dev, "can't open session: %d\n", ret);
+ return ret;
+ }
+
+ cmd_arg.func = PTA_SCMI_CMD_GET_CHANNEL;
+ cmd_arg.session = sess_arg.session;
+
+ param[0].attr = TEE_PARAM_ATTR_TYPE_VALUE_INOUT;
+ param[0].u.value.a = chan->channel_id;
+ param[0].u.value.b = PTA_SCMI_CAPS_SMT_HEADER;
+
+ ret = tee_invoke_func(sess->tee, &cmd_arg, ARRAY_SIZE(param), param);
+ if (ret || cmd_arg.ret) {
+ dev_err(dev, "Invoke failed: %d, 0x%x\n", ret, cmd_arg.ret);
+ if (!ret)
+ ret = -EPROTO;
+
+ tee_close_session(sess->tee, sess_arg.session);
+ return ret;
+ }
+
+ sess->tee_session = sess_arg.session;
+ sess->channel_hdl = param[0].u.value.a;
+
+ return 0;
+}
+
+static void close_channel(struct channel_session *sess)
+{
+ tee_close_session(sess->tee, sess->tee_session);
+}
+
+static int invoke_cmd(struct udevice *dev, struct channel_session *sess,
+ struct scmi_msg *msg)
+{
+ struct scmi_optee_channel *chan = dev_get_plat(dev);
+ struct tee_invoke_arg arg = { };
+ struct tee_param param[2] = { };
+ int ret;
+
+ scmi_write_msg_to_smt(dev, &chan->smt, msg);
+
+ arg.session = sess->tee_session;
+ param[0].attr = TEE_PARAM_ATTR_TYPE_VALUE_INPUT;
+ param[0].u.value.a = sess->channel_hdl;
+
+ if (chan->dyn_shm) {
+ arg.func = PTA_SCMI_CMD_PROCESS_SMT_CHANNEL_MESSAGE;
+ param[1].attr = TEE_PARAM_ATTR_TYPE_MEMREF_INOUT;
+ param[1].u.memref.shm = sess->tee_shm;
+ param[1].u.memref.size = SCMI_SHM_SIZE;
+ } else {
+ arg.func = PTA_SCMI_CMD_PROCESS_SMT_CHANNEL;
+ }
+
+ ret = tee_invoke_func(sess->tee, &arg, ARRAY_SIZE(param), param);
+ if (ret || arg.ret) {
+ if (!ret)
+ ret = -EPROTO;
+ } else {
+ ret = scmi_read_resp_from_smt(dev, &chan->smt, msg);
+ }
+
+ scmi_clear_smt_channel(&chan->smt);
+
+ return ret;
+}
+
+static int prepare_shm(struct udevice *dev, struct channel_session *sess)
+{
+ struct scmi_optee_channel *chan = dev_get_plat(dev);
+ int ret;
+
+ /* Static shm is already prepared by the firmware: nothing to do */
+ if (!chan->dyn_shm)
+ return 0;
+
+ chan->smt.size = SCMI_SHM_SIZE;
+
+ ret = tee_shm_alloc(sess->tee, chan->smt.size, 0, &sess->tee_shm);
+ if (ret) {
+ dev_err(dev, "Failed to allocated shmem: %d\n", ret);
+ return ret;
+ }
+
+ chan->smt.buf = sess->tee_shm->addr;
+
+ /* Initialize shm buffer for message exchanges */
+ scmi_clear_smt_channel(&chan->smt);
+
+ return 0;
+}
+
+static void release_shm(struct udevice *dev, struct channel_session *sess)
+{
+ struct scmi_optee_channel *chan = dev_get_plat(dev);
+
+ if (chan->dyn_shm)
+ tee_shm_free(sess->tee_shm);
+}
+
+static int scmi_optee_process_msg(struct udevice *dev, struct scmi_msg *msg)
+{
+ struct channel_session sess;
+ int ret;
+
+ ret = open_channel(dev, &sess);
+ if (ret)
+ return ret;
+
+ ret = prepare_shm(dev, &sess);
+ if (ret)
+ goto out;
+
+ ret = invoke_cmd(dev, &sess, msg);
+
+ release_shm(dev, &sess);
+
+out:
+ close_channel(&sess);
+
+ return ret;
+}
+
+static int scmi_optee_of_to_plat(struct udevice *dev)
+{
+ struct scmi_optee_channel *chan = dev_get_plat(dev);
+ int ret;
+
+ if (dev_read_u32(dev, "linaro,optee-channel-id", &chan->channel_id)) {
+ dev_err(dev, "Missing property linaro,optee-channel-id\n");
+ return -EINVAL;
+ }
+
+ if (dev_read_prop(dev, "shmem", NULL)) {
+ ret = scmi_dt_get_smt_buffer(dev, &chan->smt);
+ if (ret) {
+ dev_err(dev, "Failed to get smt resources: %d\n", ret);
+ return ret;
+ }
+ chan->dyn_shm = false;
+ } else {
+ chan->dyn_shm = true;
+ }
+
+ return 0;
+}
+
+static int scmi_optee_probe(struct udevice *dev)
+{
+ struct channel_session sess;
+ int ret;
+
+ /* Check OP-TEE service acknowledges the SCMI channel */
+ ret = open_channel(dev, &sess);
+ if (!ret)
+ close_channel(&sess);
+
+ return ret;
+}
+
+static const struct udevice_id scmi_optee_ids[] = {
+ { .compatible = "linaro,scmi-optee" },
+ { }
+};
+
+static const struct scmi_agent_ops scmi_optee_ops = {
+ .process_msg = scmi_optee_process_msg,
+};
+
+U_BOOT_DRIVER(scmi_optee) = {
+ .name = "scmi-over-optee",
+ .id = UCLASS_SCMI_AGENT,
+ .of_match = scmi_optee_ids,
+ .plat_auto = sizeof(struct scmi_optee_channel),
+ .of_to_plat = scmi_optee_of_to_plat,
+ .probe = scmi_optee_probe,
+ .flags = DM_FLAG_OS_PREPARE,
+ .ops = &scmi_optee_ops,
+};
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