esp-idf/components/driver/spi/gpspi/spi_slave.c

534 wiersze
20 KiB
C

/*
* SPDX-FileCopyrightText: 2015-2022 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <string.h>
#include "esp_types.h"
#include "esp_attr.h"
#include "esp_check.h"
#include "esp_intr_alloc.h"
#include "esp_log.h"
#include "esp_err.h"
#include "esp_pm.h"
#include "esp_heap_caps.h"
#include "esp_rom_sys.h"
#include "soc/lldesc.h"
#include "soc/soc_caps.h"
#include "soc/spi_periph.h"
#include "soc/soc_memory_layout.h"
#include "freertos/FreeRTOS.h"
#include "freertos/semphr.h"
#include "freertos/task.h"
#include "sdkconfig.h"
#include "driver/gpio.h"
#include "driver/spi_slave.h"
#include "hal/gpio_hal.h"
#include "hal/spi_slave_hal.h"
#include "esp_private/spi_slave_internal.h"
#include "esp_private/spi_common_internal.h"
static const char *SPI_TAG = "spi_slave";
#define SPI_CHECK(a, str, ret_val) ESP_RETURN_ON_FALSE(a, ret_val, SPI_TAG, str)
#ifdef CONFIG_SPI_SLAVE_ISR_IN_IRAM
#define SPI_SLAVE_ISR_ATTR IRAM_ATTR
#else
#define SPI_SLAVE_ISR_ATTR
#endif
#ifdef CONFIG_SPI_SLAVE_IN_IRAM
#define SPI_SLAVE_ATTR IRAM_ATTR
#else
#define SPI_SLAVE_ATTR
#endif
typedef struct {
int id;
spi_bus_config_t bus_config;
spi_slave_interface_config_t cfg;
intr_handle_t intr;
spi_slave_hal_context_t hal;
spi_slave_transaction_t *cur_trans;
uint32_t flags;
uint32_t intr_flags;
int max_transfer_sz;
QueueHandle_t trans_queue;
QueueHandle_t ret_queue;
bool dma_enabled;
bool cs_iomux;
uint8_t cs_in_signal;
uint32_t tx_dma_chan;
uint32_t rx_dma_chan;
#ifdef CONFIG_PM_ENABLE
esp_pm_lock_handle_t pm_lock;
#endif
} spi_slave_t;
static spi_slave_t *spihost[SOC_SPI_PERIPH_NUM];
static void spi_intr(void *arg);
__attribute__((always_inline))
static inline bool is_valid_host(spi_host_device_t host)
{
//SPI1 can be used as GPSPI only on ESP32
#if CONFIG_IDF_TARGET_ESP32
return host >= SPI1_HOST && host <= SPI3_HOST;
#elif (SOC_SPI_PERIPH_NUM == 2)
return host == SPI2_HOST;
#elif (SOC_SPI_PERIPH_NUM == 3)
return host >= SPI2_HOST && host <= SPI3_HOST;
#endif
}
static inline bool SPI_SLAVE_ISR_ATTR bus_is_iomux(spi_slave_t *host)
{
return host->flags&SPICOMMON_BUSFLAG_IOMUX_PINS;
}
static void SPI_SLAVE_ISR_ATTR freeze_cs(spi_slave_t *host)
{
esp_rom_gpio_connect_in_signal(GPIO_MATRIX_CONST_ONE_INPUT, host->cs_in_signal, false);
}
// Use this function instead of cs_initial to avoid overwrite the output config
// This is used in test by internal gpio matrix connections
static inline void SPI_SLAVE_ISR_ATTR restore_cs(spi_slave_t *host)
{
if (host->cs_iomux) {
gpio_ll_iomux_in(GPIO_HAL_GET_HW(GPIO_PORT_0), host->cfg.spics_io_num, host->cs_in_signal);
} else {
esp_rom_gpio_connect_in_signal(host->cfg.spics_io_num, host->cs_in_signal, false);
}
}
#if (SOC_CPU_CORES_NUM > 1) && (!CONFIG_FREERTOS_UNICORE)
typedef struct {
spi_slave_t *host;
esp_err_t *err;
} spi_ipc_param_t;
static void ipc_isr_reg_to_core(void *args)
{
spi_slave_t *host = ((spi_ipc_param_t *)args)->host;
*((spi_ipc_param_t *)args)->err = esp_intr_alloc(spicommon_irqsource_for_host(host->id), host->intr_flags | ESP_INTR_FLAG_INTRDISABLED, spi_intr, (void *)host, &host->intr);
}
#endif
esp_err_t spi_slave_initialize(spi_host_device_t host, const spi_bus_config_t *bus_config, const spi_slave_interface_config_t *slave_config, spi_dma_chan_t dma_chan)
{
bool spi_chan_claimed;
uint32_t actual_tx_dma_chan = 0;
uint32_t actual_rx_dma_chan = 0;
esp_err_t ret = ESP_OK;
esp_err_t err;
SPI_CHECK(is_valid_host(host), "invalid host", ESP_ERR_INVALID_ARG);
#ifdef CONFIG_IDF_TARGET_ESP32
SPI_CHECK(dma_chan >= SPI_DMA_DISABLED && dma_chan <= SPI_DMA_CH_AUTO, "invalid dma channel", ESP_ERR_INVALID_ARG );
#elif CONFIG_IDF_TARGET_ESP32S2
SPI_CHECK( dma_chan == SPI_DMA_DISABLED || dma_chan == (int)host || dma_chan == SPI_DMA_CH_AUTO, "invalid dma channel", ESP_ERR_INVALID_ARG );
#elif SOC_GDMA_SUPPORTED
SPI_CHECK( dma_chan == SPI_DMA_DISABLED || dma_chan == SPI_DMA_CH_AUTO, "invalid dma channel, chip only support spi dma channel auto-alloc", ESP_ERR_INVALID_ARG );
#endif
SPI_CHECK((bus_config->intr_flags & (ESP_INTR_FLAG_HIGH|ESP_INTR_FLAG_EDGE|ESP_INTR_FLAG_INTRDISABLED))==0, "intr flag not allowed", ESP_ERR_INVALID_ARG);
#ifndef CONFIG_SPI_SLAVE_ISR_IN_IRAM
SPI_CHECK((bus_config->intr_flags & ESP_INTR_FLAG_IRAM)==0, "ESP_INTR_FLAG_IRAM should be disabled when CONFIG_SPI_SLAVE_ISR_IN_IRAM is not set.", ESP_ERR_INVALID_ARG);
#endif
SPI_CHECK(slave_config->spics_io_num < 0 || GPIO_IS_VALID_GPIO(slave_config->spics_io_num), "spics pin invalid", ESP_ERR_INVALID_ARG);
//Check post_trans_cb status when `SPI_SLAVE_NO_RETURN_RESULT` flag is set.
if(slave_config->flags & SPI_SLAVE_NO_RETURN_RESULT) {
SPI_CHECK(slave_config->post_trans_cb != NULL, "use feature flag 'SPI_SLAVE_NO_RETURN_RESULT' but no post_trans_cb function sets", ESP_ERR_INVALID_ARG);
}
spi_chan_claimed=spicommon_periph_claim(host, "spi slave");
SPI_CHECK(spi_chan_claimed, "host already in use", ESP_ERR_INVALID_STATE);
spihost[host] = malloc(sizeof(spi_slave_t));
if (spihost[host] == NULL) {
ret = ESP_ERR_NO_MEM;
goto cleanup;
}
memset(spihost[host], 0, sizeof(spi_slave_t));
memcpy(&spihost[host]->cfg, slave_config, sizeof(spi_slave_interface_config_t));
memcpy(&spihost[host]->bus_config, bus_config, sizeof(spi_bus_config_t));
spihost[host]->id = host;
bool use_dma = (dma_chan != SPI_DMA_DISABLED);
spihost[host]->dma_enabled = use_dma;
if (use_dma) {
ret = spicommon_dma_chan_alloc(host, dma_chan, &actual_tx_dma_chan, &actual_rx_dma_chan);
if (ret != ESP_OK) {
goto cleanup;
}
}
err = spicommon_bus_initialize_io(host, bus_config, SPICOMMON_BUSFLAG_SLAVE|bus_config->flags, &spihost[host]->flags);
if (err!=ESP_OK) {
ret = err;
goto cleanup;
}
if (slave_config->spics_io_num >= 0) {
spicommon_cs_initialize(host, slave_config->spics_io_num, 0, !bus_is_iomux(spihost[host]));
// check and save where cs line really route through
spihost[host]->cs_iomux = (slave_config->spics_io_num == spi_periph_signal[host].spics0_iomux_pin) && bus_is_iomux(spihost[host]);
spihost[host]->cs_in_signal = spi_periph_signal[host].spics_in;
}
// The slave DMA suffers from unexpected transactions. Forbid reading if DMA is enabled by disabling the CS line.
if (use_dma) freeze_cs(spihost[host]);
int dma_desc_ct = 0;
spihost[host]->tx_dma_chan = actual_tx_dma_chan;
spihost[host]->rx_dma_chan = actual_rx_dma_chan;
if (use_dma) {
//See how many dma descriptors we need and allocate them
dma_desc_ct = (bus_config->max_transfer_sz + SPI_MAX_DMA_LEN - 1) / SPI_MAX_DMA_LEN;
if (dma_desc_ct == 0) dma_desc_ct = 1; //default to 4k when max is not given
spihost[host]->max_transfer_sz = dma_desc_ct * SPI_MAX_DMA_LEN;
} else {
//We're limited to non-DMA transfers: the SPI work registers can hold 64 bytes at most.
spihost[host]->max_transfer_sz = SOC_SPI_MAXIMUM_BUFFER_SIZE;
}
#ifdef CONFIG_PM_ENABLE
err = esp_pm_lock_create(ESP_PM_APB_FREQ_MAX, 0, "spi_slave",
&spihost[host]->pm_lock);
if (err != ESP_OK) {
ret = err;
goto cleanup;
}
// Lock APB frequency while SPI slave driver is in use
esp_pm_lock_acquire(spihost[host]->pm_lock);
#endif //CONFIG_PM_ENABLE
//Create queues
spihost[host]->trans_queue = xQueueCreate(slave_config->queue_size, sizeof(spi_slave_transaction_t *));
if (!spihost[host]->trans_queue) {
ret = ESP_ERR_NO_MEM;
goto cleanup;
}
if(!(slave_config->flags & SPI_SLAVE_NO_RETURN_RESULT)) {
spihost[host]->ret_queue = xQueueCreate(slave_config->queue_size, sizeof(spi_slave_transaction_t *));
if (!spihost[host]->ret_queue) {
ret = ESP_ERR_NO_MEM;
goto cleanup;
}
}
#if (SOC_CPU_CORES_NUM > 1) && (!CONFIG_FREERTOS_UNICORE)
if(bus_config->isr_cpu_id > INTR_CPU_ID_AUTO) {
spihost[host]->intr_flags = bus_config->intr_flags;
SPI_CHECK(bus_config->isr_cpu_id <= INTR_CPU_ID_1, "invalid core id", ESP_ERR_INVALID_ARG);
spi_ipc_param_t ipc_args = {
.host = spihost[host],
.err = &err,
};
esp_ipc_call_blocking(INTR_CPU_CONVERT_ID(bus_config->isr_cpu_id), ipc_isr_reg_to_core, (void *)&ipc_args);
} else
#endif
{
err = esp_intr_alloc(spicommon_irqsource_for_host(host), bus_config->intr_flags | ESP_INTR_FLAG_INTRDISABLED, spi_intr, (void *)spihost[host], &spihost[host]->intr);
}
if (err != ESP_OK) {
ret = err;
goto cleanup;
}
spi_slave_hal_context_t *hal = &spihost[host]->hal;
//assign the SPI, RX DMA and TX DMA peripheral registers beginning address
spi_slave_hal_config_t hal_config = {
.host_id = host,
.dma_in = SPI_LL_GET_HW(host),
.dma_out = SPI_LL_GET_HW(host)
};
spi_slave_hal_init(hal, &hal_config);
if (dma_desc_ct) {
hal->dmadesc_tx = heap_caps_malloc(sizeof(lldesc_t) * dma_desc_ct, MALLOC_CAP_DMA);
hal->dmadesc_rx = heap_caps_malloc(sizeof(lldesc_t) * dma_desc_ct, MALLOC_CAP_DMA);
if (!hal->dmadesc_tx || !hal->dmadesc_rx) {
ret = ESP_ERR_NO_MEM;
goto cleanup;
}
}
hal->dmadesc_n = dma_desc_ct;
hal->rx_lsbfirst = (slave_config->flags & SPI_SLAVE_RXBIT_LSBFIRST) ? 1 : 0;
hal->tx_lsbfirst = (slave_config->flags & SPI_SLAVE_TXBIT_LSBFIRST) ? 1 : 0;
hal->mode = slave_config->mode;
hal->use_dma = use_dma;
hal->tx_dma_chan = actual_tx_dma_chan;
hal->rx_dma_chan = actual_rx_dma_chan;
spi_slave_hal_setup_device(hal);
return ESP_OK;
cleanup:
if (spihost[host]) {
if (spihost[host]->trans_queue) vQueueDelete(spihost[host]->trans_queue);
if (spihost[host]->ret_queue) vQueueDelete(spihost[host]->ret_queue);
free(spihost[host]->hal.dmadesc_tx);
free(spihost[host]->hal.dmadesc_rx);
#ifdef CONFIG_PM_ENABLE
if (spihost[host]->pm_lock) {
esp_pm_lock_release(spihost[host]->pm_lock);
esp_pm_lock_delete(spihost[host]->pm_lock);
}
#endif
}
spi_slave_hal_deinit(&spihost[host]->hal);
if (spihost[host]->dma_enabled) {
spicommon_dma_chan_free(host);
}
free(spihost[host]);
spihost[host] = NULL;
spicommon_periph_free(host);
return ret;
}
esp_err_t spi_slave_free(spi_host_device_t host)
{
SPI_CHECK(is_valid_host(host), "invalid host", ESP_ERR_INVALID_ARG);
SPI_CHECK(spihost[host], "host not slave", ESP_ERR_INVALID_ARG);
if (spihost[host]->trans_queue) vQueueDelete(spihost[host]->trans_queue);
if (spihost[host]->ret_queue) vQueueDelete(spihost[host]->ret_queue);
if (spihost[host]->dma_enabled) {
spicommon_dma_chan_free(host);
}
spicommon_bus_free_io_cfg(&spihost[host]->bus_config);
free(spihost[host]->hal.dmadesc_tx);
free(spihost[host]->hal.dmadesc_rx);
esp_intr_free(spihost[host]->intr);
#ifdef CONFIG_PM_ENABLE
esp_pm_lock_release(spihost[host]->pm_lock);
esp_pm_lock_delete(spihost[host]->pm_lock);
#endif //CONFIG_PM_ENABLE
free(spihost[host]);
spihost[host] = NULL;
spicommon_periph_free(host);
return ESP_OK;
}
/**
* @note
* This API is used to reset SPI Slave transaction queue. After calling this function:
* - The SPI Slave transaction queue will be reset.
*
* Therefore, this API shouldn't be called when the corresponding SPI Master is doing an SPI transaction.
*
* @note
* We don't actually need to enter a critical section here.
* SPI Slave ISR will only get triggered when its corresponding SPI Master's transaction is done.
* As we don't expect this function to be called when its corresponding SPI Master is doing an SPI transaction,
* so concurrent call to these registers won't happen
*
*/
esp_err_t SPI_SLAVE_ATTR spi_slave_queue_reset(spi_host_device_t host)
{
SPI_CHECK(is_valid_host(host), "invalid host", ESP_ERR_INVALID_ARG);
SPI_CHECK(spihost[host], "host not slave", ESP_ERR_INVALID_ARG);
esp_intr_disable(spihost[host]->intr);
spi_ll_set_int_stat(spihost[host]->hal.hw);
spihost[host]->cur_trans = NULL;
xQueueReset(spihost[host]->trans_queue);
return ESP_OK;
}
esp_err_t SPI_SLAVE_ISR_ATTR spi_slave_queue_reset_isr(spi_host_device_t host)
{
ESP_RETURN_ON_FALSE_ISR(is_valid_host(host), ESP_ERR_INVALID_ARG, SPI_TAG, "invalid host");
ESP_RETURN_ON_FALSE_ISR(spihost[host], ESP_ERR_INVALID_ARG, SPI_TAG, "host not slave");
spi_slave_transaction_t *trans = NULL;
BaseType_t do_yield = pdFALSE;
while( pdFALSE == xQueueIsQueueEmptyFromISR(spihost[host]->trans_queue)) {
xQueueReceiveFromISR(spihost[host]->trans_queue, &trans, &do_yield);
}
if (do_yield) {
portYIELD_FROM_ISR();
}
spihost[host]->cur_trans = NULL;
return ESP_OK;
}
esp_err_t SPI_SLAVE_ATTR spi_slave_queue_trans(spi_host_device_t host, const spi_slave_transaction_t *trans_desc, TickType_t ticks_to_wait)
{
BaseType_t r;
SPI_CHECK(is_valid_host(host), "invalid host", ESP_ERR_INVALID_ARG);
SPI_CHECK(spihost[host], "host not slave", ESP_ERR_INVALID_ARG);
SPI_CHECK(spihost[host]->dma_enabled == 0 || trans_desc->tx_buffer==NULL || esp_ptr_dma_capable(trans_desc->tx_buffer),
"txdata not in DMA-capable memory", ESP_ERR_INVALID_ARG);
SPI_CHECK(spihost[host]->dma_enabled == 0 || trans_desc->rx_buffer==NULL ||
(esp_ptr_dma_capable(trans_desc->rx_buffer) && esp_ptr_word_aligned(trans_desc->rx_buffer) &&
(trans_desc->length%4==0)),
"rxdata not in DMA-capable memory or not WORD aligned", ESP_ERR_INVALID_ARG);
SPI_CHECK(trans_desc->length <= spihost[host]->max_transfer_sz * 8, "data transfer > host maximum", ESP_ERR_INVALID_ARG);
r = xQueueSend(spihost[host]->trans_queue, (void *)&trans_desc, ticks_to_wait);
if (!r) return ESP_ERR_TIMEOUT;
esp_intr_enable(spihost[host]->intr);
return ESP_OK;
}
esp_err_t SPI_SLAVE_ISR_ATTR spi_slave_queue_trans_isr(spi_host_device_t host, const spi_slave_transaction_t *trans_desc)
{
BaseType_t r;
BaseType_t do_yield = pdFALSE;
ESP_RETURN_ON_FALSE_ISR(is_valid_host(host), ESP_ERR_INVALID_ARG, SPI_TAG, "invalid host");
ESP_RETURN_ON_FALSE_ISR(spihost[host], ESP_ERR_INVALID_ARG, SPI_TAG, "host not slave");
ESP_RETURN_ON_FALSE_ISR(spihost[host]->dma_enabled == 0 || trans_desc->tx_buffer==NULL || esp_ptr_dma_capable(trans_desc->tx_buffer),
ESP_ERR_INVALID_ARG, SPI_TAG, "txdata not in DMA-capable memory");
ESP_RETURN_ON_FALSE_ISR(spihost[host]->dma_enabled == 0 || trans_desc->rx_buffer==NULL ||
(esp_ptr_dma_capable(trans_desc->rx_buffer) && esp_ptr_word_aligned(trans_desc->rx_buffer) &&
(trans_desc->length%4==0)),
ESP_ERR_INVALID_ARG, SPI_TAG, "rxdata not in DMA-capable memory or not WORD aligned");
ESP_RETURN_ON_FALSE_ISR(trans_desc->length <= spihost[host]->max_transfer_sz * 8, ESP_ERR_INVALID_ARG, SPI_TAG, "data transfer > host maximum");
r = xQueueSendFromISR(spihost[host]->trans_queue, (void *)&trans_desc, &do_yield);
if (!r) {
return ESP_ERR_NO_MEM;
}
if (do_yield) {
portYIELD_FROM_ISR();
}
return ESP_OK;
}
esp_err_t SPI_SLAVE_ATTR spi_slave_get_trans_result(spi_host_device_t host, spi_slave_transaction_t **trans_desc, TickType_t ticks_to_wait)
{
BaseType_t r;
SPI_CHECK(is_valid_host(host), "invalid host", ESP_ERR_INVALID_ARG);
SPI_CHECK(spihost[host], "host not slave", ESP_ERR_INVALID_ARG);
//if SPI_SLAVE_NO_RETURN_RESULT is set, ret_queue will always be empty
SPI_CHECK(!(spihost[host]->cfg.flags & SPI_SLAVE_NO_RETURN_RESULT), "API not Supported!", ESP_ERR_NOT_SUPPORTED);
r = xQueueReceive(spihost[host]->ret_queue, (void *)trans_desc, ticks_to_wait);
if (!r) return ESP_ERR_TIMEOUT;
return ESP_OK;
}
esp_err_t SPI_SLAVE_ATTR spi_slave_transmit(spi_host_device_t host, spi_slave_transaction_t *trans_desc, TickType_t ticks_to_wait)
{
esp_err_t ret;
spi_slave_transaction_t *ret_trans;
//ToDo: check if any spi transfers in flight
ret = spi_slave_queue_trans(host, trans_desc, ticks_to_wait);
if (ret != ESP_OK) return ret;
ret = spi_slave_get_trans_result(host, &ret_trans, ticks_to_wait);
if (ret != ESP_OK) return ret;
assert(ret_trans == trans_desc);
return ESP_OK;
}
#if CONFIG_IDF_TARGET_ESP32
static void SPI_SLAVE_ISR_ATTR spi_slave_restart_after_dmareset(void *arg)
{
spi_slave_t *host = (spi_slave_t *)arg;
esp_intr_enable(host->intr);
}
#endif //#if CONFIG_IDF_TARGET_ESP32
//This is run in interrupt context and apart from initialization and destruction, this is the only code
//touching the host (=spihost[x]) variable. The rest of the data arrives in queues. That is why there are
//no muxes in this code.
static void SPI_SLAVE_ISR_ATTR spi_intr(void *arg)
{
BaseType_t r;
BaseType_t do_yield = pdFALSE;
spi_slave_transaction_t *trans = NULL;
spi_slave_t *host = (spi_slave_t *)arg;
spi_slave_hal_context_t *hal = &host->hal;
assert(spi_slave_hal_usr_is_done(hal));
bool use_dma = host->dma_enabled;
if (host->cur_trans) {
// When DMA is enabled, the slave rx dma suffers from unexpected transactions. Forbid reading until transaction ready.
if (use_dma) freeze_cs(host);
spi_slave_hal_store_result(hal);
host->cur_trans->trans_len = spi_slave_hal_get_rcv_bitlen(hal);
#if CONFIG_IDF_TARGET_ESP32
//This workaround is only for esp32
if (spi_slave_hal_dma_need_reset(hal)) {
//On ESP32, actual_tx_dma_chan and actual_rx_dma_chan are always same
spicommon_dmaworkaround_req_reset(host->tx_dma_chan, spi_slave_restart_after_dmareset, host);
}
#endif //#if CONFIG_IDF_TARGET_ESP32
if (host->cfg.post_trans_cb) host->cfg.post_trans_cb(host->cur_trans);
if(!(host->cfg.flags & SPI_SLAVE_NO_RETURN_RESULT)) {
xQueueSendFromISR(host->ret_queue, &host->cur_trans, &do_yield);
}
host->cur_trans = NULL;
}
#if CONFIG_IDF_TARGET_ESP32
//This workaround is only for esp32
if (use_dma) {
//On ESP32, actual_tx_dma_chan and actual_rx_dma_chan are always same
spicommon_dmaworkaround_idle(host->tx_dma_chan);
if (spicommon_dmaworkaround_reset_in_progress()) {
//We need to wait for the reset to complete. Disable int (will be re-enabled on reset callback) and exit isr.
esp_intr_disable(host->intr);
if (do_yield) portYIELD_FROM_ISR();
return;
}
}
#endif //#if CONFIG_IDF_TARGET_ESP32
//Disable interrupt before checking to avoid concurrency issue.
esp_intr_disable(host->intr);
//Grab next transaction
r = xQueueReceiveFromISR(host->trans_queue, &trans, &do_yield);
if (r) {
// sanity check
assert(trans);
//enable the interrupt again if there is packet to send
esp_intr_enable(host->intr);
//We have a transaction. Send it.
host->cur_trans = trans;
hal->bitlen = trans->length;
hal->rx_buffer = trans->rx_buffer;
hal->tx_buffer = trans->tx_buffer;
#if CONFIG_IDF_TARGET_ESP32
if (use_dma) {
//This workaround is only for esp32
//On ESP32, actual_tx_dma_chan and actual_rx_dma_chan are always same
spicommon_dmaworkaround_transfer_active(host->tx_dma_chan);
}
#endif //#if CONFIG_IDF_TARGET_ESP32
spi_slave_hal_prepare_data(hal);
//The slave rx dma get disturbed by unexpected transaction. Only connect the CS when slave is ready.
if (use_dma) {
restore_cs(host);
}
//Kick off transfer
spi_slave_hal_user_start(hal);
if (host->cfg.post_setup_cb) host->cfg.post_setup_cb(trans);
}
if (do_yield) portYIELD_FROM_ISR();
}