drivers/scmi-msg: smt entry points for incoming messages
This change implements SCMI channels for reading a SCMI message from a
shared memory and call the SCMI message drivers to route the message
to the target platform services.
SMT refers to the shared memory management protocol which is used
to get/put message/response in shared memory. SMT is a 28byte header
stating shared memory state and exchanged protocol data.
The processing entry for a SCMI message can be a secure interrupt
or fastcall SMCCC invocation.
SMT description in this implementation is based on the OP-TEE
project [1] itself based in the SCP-firmware implementation [2].
Link: [1] a58c4d706d
Link: [2] https://github.com/ARM-software/SCP-firmware.git
Change-Id: I416c7dab5c67954c6fe80bae8d8cdfdcda66873e
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
This commit is contained in:
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// SPDX-License-Identifier: BSD-3-Clause
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/*
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* Copyright (c) 2015-2019, Arm Limited and Contributors. All rights reserved.
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* Copyright (c) 2019-2020, Linaro Limited
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*/
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#include <assert.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include <string.h>
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#include <drivers/st/scmi-msg.h>
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#include <drivers/st/scmi.h>
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#include <lib/cassert.h>
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#include <lib/mmio.h>
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#include <lib/spinlock.h>
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#include <lib/utils.h>
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#include <plat/common/platform.h>
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#include "common.h"
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/* Legacy SMT/SCMI messages are 128 bytes at most including SMT header */
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#define SCMI_PLAYLOAD_MAX 92U
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#define SCMI_PLAYLOAD_U32_MAX (SCMI_PLAYLOAD_MAX / sizeof(uint32_t))
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/**
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* struct smt_header - SMT formatted header for SMT base shared memory transfer
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*
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* @status: Bit flags, see SMT_STATUS_*
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* @flags: Bit flags, see SMT_FLAG_*
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* @length: Byte size of message payload (variable) + ::message_header (32bit)
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* payload: SCMI message payload data
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*/
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struct smt_header {
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uint32_t reserved0;
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uint32_t status;
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uint64_t reserved1;
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uint32_t flags;
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uint32_t length; /* message_header + payload */
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uint32_t message_header;
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uint32_t payload[];
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};
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CASSERT(SCMI_PLAYLOAD_MAX + sizeof(struct smt_header) <= SMT_BUF_SLOT_SIZE,
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assert_scmi_message_max_length_fits_in_smt_buffer_slot);
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/* Flag set in smt_header::status when SMT does not contain pending message */
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#define SMT_STATUS_FREE BIT(0)
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/* Flag set in smt_header::status when SMT reports an error */
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#define SMT_STATUS_ERROR BIT(1)
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/* Flag set in smt_header::flags when SMT uses interrupts */
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#define SMT_FLAG_INTR_ENABLED BIT(1)
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/* Bit fields packed in smt_header::message_header */
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#define SMT_MSG_ID_MASK GENMASK_32(7, 0)
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#define SMT_HDR_MSG_ID(_hdr) ((_hdr) & SMT_MSG_ID_MASK)
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#define SMT_MSG_TYPE_MASK GENMASK_32(9, 8)
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#define SMT_HDR_TYPE_ID(_hdr) (((_hdr) & SMT_MSG_TYPE_MASK) >> 8)
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#define SMT_MSG_PROT_ID_MASK GENMASK_32(17, 10)
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#define SMT_HDR_PROT_ID(_hdr) (((_hdr) & SMT_MSG_PROT_ID_MASK) >> 10)
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/*
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* Provision input message payload buffers for fastcall SMC context entries
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* and for interrupt context execution entries.
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*/
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static uint32_t fast_smc_payload[PLATFORM_CORE_COUNT][SCMI_PLAYLOAD_U32_MAX];
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static uint32_t interrupt_payload[PLATFORM_CORE_COUNT][SCMI_PLAYLOAD_U32_MAX];
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/* SMP protection on channel access */
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static struct spinlock smt_channels_lock;
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/* If channel is not busy, set busy and return true, otherwise return false */
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static bool channel_set_busy(struct scmi_msg_channel *chan)
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{
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bool channel_is_busy;
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spin_lock(&smt_channels_lock);
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channel_is_busy = chan->busy;
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if (!channel_is_busy) {
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chan->busy = true;
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}
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spin_unlock(&smt_channels_lock);
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return !channel_is_busy;
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}
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static void channel_release_busy(struct scmi_msg_channel *chan)
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{
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chan->busy = false;
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}
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static struct smt_header *channel_to_smt_hdr(struct scmi_msg_channel *chan)
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{
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return (struct smt_header *)chan->shm_addr;
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}
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/*
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* Creates a SCMI message instance in secure memory and pushes it in the SCMI
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* message drivers. Message structure contains SCMI protocol meta-data and
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* references to input payload in secure memory and output message buffer
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* in shared memory.
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*/
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static void scmi_proccess_smt(unsigned int agent_id, uint32_t *payload_buf)
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{
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struct scmi_msg_channel *chan;
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struct smt_header *smt_hdr;
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size_t in_payload_size;
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uint32_t smt_status;
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struct scmi_msg msg;
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bool error = true;
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chan = plat_scmi_get_channel(agent_id);
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if (chan == NULL) {
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return;
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}
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smt_hdr = channel_to_smt_hdr(chan);
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assert(smt_hdr);
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smt_status = __atomic_load_n(&smt_hdr->status, __ATOMIC_RELAXED);
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if (!channel_set_busy(chan)) {
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VERBOSE("SCMI channel %u busy", agent_id);
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goto out;
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}
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in_payload_size = __atomic_load_n(&smt_hdr->length, __ATOMIC_RELAXED) -
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sizeof(smt_hdr->message_header);
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if (in_payload_size > SCMI_PLAYLOAD_MAX) {
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VERBOSE("SCMI payload too big %u", in_payload_size);
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goto out;
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}
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if ((smt_status & (SMT_STATUS_ERROR | SMT_STATUS_FREE)) != 0U) {
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VERBOSE("SCMI channel bad status 0x%x",
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smt_hdr->status & (SMT_STATUS_ERROR | SMT_STATUS_FREE));
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goto out;
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}
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/* Fill message */
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zeromem(&msg, sizeof(msg));
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msg.in = (char *)payload_buf;
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msg.in_size = in_payload_size;
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msg.out = (char *)smt_hdr->payload;
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msg.out_size = chan->shm_size - sizeof(*smt_hdr);
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assert((msg.out != NULL) && (msg.out_size >= sizeof(int32_t)));
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/* Here the payload is copied in secure memory */
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memcpy(msg.in, smt_hdr->payload, in_payload_size);
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msg.protocol_id = SMT_HDR_PROT_ID(smt_hdr->message_header);
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msg.message_id = SMT_HDR_MSG_ID(smt_hdr->message_header);
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msg.agent_id = agent_id;
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scmi_process_message(&msg);
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/* Update message length with the length of the response message */
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smt_hdr->length = msg.out_size_out + sizeof(smt_hdr->message_header);
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channel_release_busy(chan);
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error = false;
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out:
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if (error) {
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VERBOSE("SCMI error");
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smt_hdr->status |= SMT_STATUS_ERROR | SMT_STATUS_FREE;
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} else {
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smt_hdr->status |= SMT_STATUS_FREE;
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}
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}
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void scmi_smt_fastcall_smc_entry(unsigned int agent_id)
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{
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scmi_proccess_smt(agent_id,
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fast_smc_payload[plat_my_core_pos()]);
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}
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void scmi_smt_interrupt_entry(unsigned int agent_id)
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{
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scmi_proccess_smt(agent_id,
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interrupt_payload[plat_my_core_pos()]);
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}
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/* Init a SMT header for a shared memory buffer: state it a free/no-error */
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void scmi_smt_init_agent_channel(struct scmi_msg_channel *chan)
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{
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if (chan != NULL) {
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struct smt_header *smt_header = channel_to_smt_hdr(chan);
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if (smt_header != NULL) {
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memset(smt_header, 0, sizeof(*smt_header));
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smt_header->status = SMT_STATUS_FREE;
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return;
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}
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}
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panic();
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}
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@ -32,6 +32,32 @@ struct scmi_msg_channel {
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const char *agent_name;
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};
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/*
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* Initialize SMT memory buffer, called by platform at init for each
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* agent channel using the SMT header format.
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*
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* @chan: Pointer to the channel shared memory to be initialized
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*/
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void scmi_smt_init_agent_channel(struct scmi_msg_channel *chan);
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/*
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* Process SMT formatted message in a fastcall SMC execution context.
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* Called by platform on SMC entry. When returning, output message is
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* available in shared memory for agent to read the response.
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*
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* @agent_id: SCMI agent ID the SMT belongs to
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*/
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void scmi_smt_fastcall_smc_entry(unsigned int agent_id);
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/*
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* Process SMT formatted message in a secure interrupt execution context.
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* Called by platform interrupt handler. When returning, output message is
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* available in shared memory for agent to read the response.
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*
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* @agent_id: SCMI agent ID the SMT belongs to
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*/
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void scmi_smt_interrupt_entry(unsigned int agent_id);
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/* Platform callback functions */
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/*
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