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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>
pull/1979/head
Etienne Carriere 5 years ago
committed by Etienne Carriere
parent
6cc2c1cbed
commit
7d6fa6ecbe
2 changed files with 232 additions and 0 deletions
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  1. 206
      drivers/st/scmi-msg/smt.c
  2. 26
      include/drivers/st/scmi-msg.h

206
drivers/st/scmi-msg/smt.c
View File

@ -0,0 +1,206 @@
// SPDX-License-Identifier: BSD-3-Clause
/*
* Copyright (c) 2015-2019, Arm Limited and Contributors. All rights reserved.
* Copyright (c) 2019-2020, Linaro Limited
*/
#include <assert.h>
#include <stdbool.h>
#include <stdint.h>
#include <string.h>
#include <drivers/st/scmi-msg.h>
#include <drivers/st/scmi.h>
#include <lib/cassert.h>
#include <lib/mmio.h>
#include <lib/spinlock.h>
#include <lib/utils.h>
#include <plat/common/platform.h>
#include "common.h"
/* Legacy SMT/SCMI messages are 128 bytes at most including SMT header */
#define SCMI_PLAYLOAD_MAX 92U
#define SCMI_PLAYLOAD_U32_MAX (SCMI_PLAYLOAD_MAX / sizeof(uint32_t))
/**
* struct smt_header - SMT formatted header for SMT base shared memory transfer
*
* @status: Bit flags, see SMT_STATUS_*
* @flags: Bit flags, see SMT_FLAG_*
* @length: Byte size of message payload (variable) + ::message_header (32bit)
* payload: SCMI message payload data
*/
struct smt_header {
uint32_t reserved0;
uint32_t status;
uint64_t reserved1;
uint32_t flags;
uint32_t length; /* message_header + payload */
uint32_t message_header;
uint32_t payload[];
};
CASSERT(SCMI_PLAYLOAD_MAX + sizeof(struct smt_header) <= SMT_BUF_SLOT_SIZE,
assert_scmi_message_max_length_fits_in_smt_buffer_slot);
/* Flag set in smt_header::status when SMT does not contain pending message */
#define SMT_STATUS_FREE BIT(0)
/* Flag set in smt_header::status when SMT reports an error */
#define SMT_STATUS_ERROR BIT(1)
/* Flag set in smt_header::flags when SMT uses interrupts */
#define SMT_FLAG_INTR_ENABLED BIT(1)
/* Bit fields packed in smt_header::message_header */
#define SMT_MSG_ID_MASK GENMASK_32(7, 0)
#define SMT_HDR_MSG_ID(_hdr) ((_hdr) & SMT_MSG_ID_MASK)
#define SMT_MSG_TYPE_MASK GENMASK_32(9, 8)
#define SMT_HDR_TYPE_ID(_hdr) (((_hdr) & SMT_MSG_TYPE_MASK) >> 8)
#define SMT_MSG_PROT_ID_MASK GENMASK_32(17, 10)
#define SMT_HDR_PROT_ID(_hdr) (((_hdr) & SMT_MSG_PROT_ID_MASK) >> 10)
/*
* Provision input message payload buffers for fastcall SMC context entries
* and for interrupt context execution entries.
*/
static uint32_t fast_smc_payload[PLATFORM_CORE_COUNT][SCMI_PLAYLOAD_U32_MAX];
static uint32_t interrupt_payload[PLATFORM_CORE_COUNT][SCMI_PLAYLOAD_U32_MAX];
/* SMP protection on channel access */
static struct spinlock smt_channels_lock;
/* If channel is not busy, set busy and return true, otherwise return false */
static bool channel_set_busy(struct scmi_msg_channel *chan)
{
bool channel_is_busy;
spin_lock(&smt_channels_lock);
channel_is_busy = chan->busy;
if (!channel_is_busy) {
chan->busy = true;
}
spin_unlock(&smt_channels_lock);
return !channel_is_busy;
}
static void channel_release_busy(struct scmi_msg_channel *chan)
{
chan->busy = false;
}
static struct smt_header *channel_to_smt_hdr(struct scmi_msg_channel *chan)
{
return (struct smt_header *)chan->shm_addr;
}
/*
* Creates a SCMI message instance in secure memory and pushes it in the SCMI
* message drivers. Message structure contains SCMI protocol meta-data and
* references to input payload in secure memory and output message buffer
* in shared memory.
*/
static void scmi_proccess_smt(unsigned int agent_id, uint32_t *payload_buf)
{
struct scmi_msg_channel *chan;
struct smt_header *smt_hdr;
size_t in_payload_size;
uint32_t smt_status;
struct scmi_msg msg;
bool error = true;
chan = plat_scmi_get_channel(agent_id);
if (chan == NULL) {
return;
}
smt_hdr = channel_to_smt_hdr(chan);
assert(smt_hdr);
smt_status = __atomic_load_n(&smt_hdr->status, __ATOMIC_RELAXED);
if (!channel_set_busy(chan)) {
VERBOSE("SCMI channel %u busy", agent_id);
goto out;
}
in_payload_size = __atomic_load_n(&smt_hdr->length, __ATOMIC_RELAXED) -
sizeof(smt_hdr->message_header);
if (in_payload_size > SCMI_PLAYLOAD_MAX) {
VERBOSE("SCMI payload too big %u", in_payload_size);
goto out;
}
if ((smt_status & (SMT_STATUS_ERROR | SMT_STATUS_FREE)) != 0U) {
VERBOSE("SCMI channel bad status 0x%x",
smt_hdr->status & (SMT_STATUS_ERROR | SMT_STATUS_FREE));
goto out;
}
/* Fill message */
zeromem(&msg, sizeof(msg));
msg.in = (char *)payload_buf;
msg.in_size = in_payload_size;
msg.out = (char *)smt_hdr->payload;
msg.out_size = chan->shm_size - sizeof(*smt_hdr);
assert((msg.out != NULL) && (msg.out_size >= sizeof(int32_t)));
/* Here the payload is copied in secure memory */
memcpy(msg.in, smt_hdr->payload, in_payload_size);
msg.protocol_id = SMT_HDR_PROT_ID(smt_hdr->message_header);
msg.message_id = SMT_HDR_MSG_ID(smt_hdr->message_header);
msg.agent_id = agent_id;
scmi_process_message(&msg);
/* Update message length with the length of the response message */
smt_hdr->length = msg.out_size_out + sizeof(smt_hdr->message_header);
channel_release_busy(chan);
error = false;
out:
if (error) {
VERBOSE("SCMI error");
smt_hdr->status |= SMT_STATUS_ERROR | SMT_STATUS_FREE;
} else {
smt_hdr->status |= SMT_STATUS_FREE;
}
}
void scmi_smt_fastcall_smc_entry(unsigned int agent_id)
{
scmi_proccess_smt(agent_id,
fast_smc_payload[plat_my_core_pos()]);
}
void scmi_smt_interrupt_entry(unsigned int agent_id)
{
scmi_proccess_smt(agent_id,
interrupt_payload[plat_my_core_pos()]);
}
/* Init a SMT header for a shared memory buffer: state it a free/no-error */
void scmi_smt_init_agent_channel(struct scmi_msg_channel *chan)
{
if (chan != NULL) {
struct smt_header *smt_header = channel_to_smt_hdr(chan);
if (smt_header != NULL) {
memset(smt_header, 0, sizeof(*smt_header));
smt_header->status = SMT_STATUS_FREE;
return;
}
}
panic();
}

26
include/drivers/st/scmi-msg.h
View File

@ -32,6 +32,32 @@ struct scmi_msg_channel {
const char *agent_name;
};
/*
* Initialize SMT memory buffer, called by platform at init for each
* agent channel using the SMT header format.
*
* @chan: Pointer to the channel shared memory to be initialized
*/
void scmi_smt_init_agent_channel(struct scmi_msg_channel *chan);
/*
* Process SMT formatted message in a fastcall SMC execution context.
* Called by platform on SMC entry. When returning, output message is
* available in shared memory for agent to read the response.
*
* @agent_id: SCMI agent ID the SMT belongs to
*/
void scmi_smt_fastcall_smc_entry(unsigned int agent_id);
/*
* Process SMT formatted message in a secure interrupt execution context.
* Called by platform interrupt handler. When returning, output message is
* available in shared memory for agent to read the response.
*
* @agent_id: SCMI agent ID the SMT belongs to
*/
void scmi_smt_interrupt_entry(unsigned int agent_id);
/* Platform callback functions */
/*

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