介绍

SPI总线由摩托罗拉公司开发，是一种全双工同步串行总线，由四个IO口组成：CS、SCLK、MISO、MOSI；通常用于CPU和外设之间进行通信，常见的SPI总线设备有：TFT LCD、QSPI FLASH、时钟模块、IMU等；NXP-MCXA153开发板上集成了两路SPI总线，本次实验将重点介绍RT-Thread系统中SPI BSP驱动的移植过程

移植流程

以SPI0为例

① 在board里边添加相应的外设：配置spi0外设为复位状态、设置GPIO引脚功能

② 添加相应的Kconfig开关，用以指示相应的外设开启与关闭（本质是通过宏定义或者条件编译的方式）

③ 根据SDK_2_14_2_FRDM-MCXA153提供的spi示例工程编写spi总线驱动，需要实现几个关键的函数

• rt_hw_spi_init
• spi_configure
• spixfer

④ 添加相应的库文件依赖：fsl_lpspi.c、fsl_lpspi_edma.c

引脚对应关系

序号	GPIO	function
1	P1_3	CS
2	P1_1	SCLK
3	P1_2	MISO
4	P1_0	MOSI

驱动文件

board.c

在rt_hw_board_init函数里加入以下代码

edma_config_t userConfig = {0};
EDMA_GetDefaultConfig(&userConfig);
EDMA_Init(DMA0, &userConfig);

pin_mux.c

在BOARD_InitPins函数里加入以下代码

#ifdef BSP_USING_SPI0
	RESET_ReleasePeripheralReset(kLPSPI0_RST_SHIFT_RSTn);
    const port_pin_config_t port1_0_pin56_config = {/* Internal pull-up/down resistor is disabled */
                                                    kPORT_PullDisable,
                                                    /* Low internal pull resistor value is selected. */
                                                    kPORT_LowPullResistor,
                                                    /* Fast slew rate is configured */
                                                    kPORT_FastSlewRate,
                                                    /* Passive input filter is disabled */
                                                    kPORT_PassiveFilterDisable,
                                                    /* Open drain output is disabled */
                                                    kPORT_OpenDrainDisable,
                                                    /* Low drive strength is configured */
                                                    kPORT_LowDriveStrength,
                                                    /* Normal drive strength is configured */
                                                    kPORT_NormalDriveStrength,
                                                    /* Pin is configured as LPSPI0_SDO */
                                                    kPORT_MuxAlt2,
                                                    /* Digital input enabled */
                                                    kPORT_InputBufferEnable,
                                                    /* Digital input is not inverted */
                                                    kPORT_InputNormal,
                                                    /* Pin Control Register fields [15:0] are not locked */
                                                    kPORT_UnlockRegister};
    /* PORT1_0 (pin 56) is configured as LPSPI0_SDO */
    PORT_SetPinConfig(PORT1, 0U, &port1_0_pin56_config);

    const port_pin_config_t port1_1_pin57_config = {/* Internal pull-up/down resistor is disabled */
                                                    kPORT_PullDisable,
                                                    /* Low internal pull resistor value is selected. */
                                                    kPORT_LowPullResistor,
                                                    /* Fast slew rate is configured */
                                                    kPORT_FastSlewRate,
                                                    /* Passive input filter is disabled */
                                                    kPORT_PassiveFilterDisable,
                                                    /* Open drain output is disabled */
                                                    kPORT_OpenDrainDisable,
                                                    /* Low drive strength is configured */
                                                    kPORT_LowDriveStrength,
                                                    /* Normal drive strength is configured */
                                                    kPORT_NormalDriveStrength,
                                                    /* Pin is configured as LPSPI0_SCK */
                                                    kPORT_MuxAlt2,
                                                    /* Digital input enabled */
                                                    kPORT_InputBufferEnable,
                                                    /* Digital input is not inverted */
                                                    kPORT_InputNormal,
                                                    /* Pin Control Register fields [15:0] are not locked */
                                                    kPORT_UnlockRegister};
    /* PORT1_1 (pin 57) is configured as LPSPI0_SCK */
    PORT_SetPinConfig(PORT1, 1U, &port1_1_pin57_config);

    const port_pin_config_t port1_2_pin58_config = {/* Internal pull-up/down resistor is disabled */
                                                    kPORT_PullDisable,
                                                    /* Low internal pull resistor value is selected. */
                                                    kPORT_LowPullResistor,
                                                    /* Fast slew rate is configured */
                                                    kPORT_FastSlewRate,
                                                    /* Passive input filter is disabled */
                                                    kPORT_PassiveFilterDisable,
                                                    /* Open drain output is disabled */
                                                    kPORT_OpenDrainDisable,
                                                    /* Low drive strength is configured */
                                                    kPORT_LowDriveStrength,
                                                    /* Normal drive strength is configured */
                                                    kPORT_NormalDriveStrength,
                                                    /* Pin is configured as LPSPI0_SDI */
                                                    kPORT_MuxAlt2,
                                                    /* Digital input enabled */
                                                    kPORT_InputBufferEnable,
                                                    /* Digital input is not inverted */
                                                    kPORT_InputNormal,
                                                    /* Pin Control Register fields [15:0] are not locked */
                                                    kPORT_UnlockRegister};
    /* PORT1_2 (pin 58) is configured as LPSPI0_SDI */
    PORT_SetPinConfig(PORT1, 2U, &port1_2_pin58_config);

    const port_pin_config_t port1_3_pin59_config = {/* Internal pull-up/down resistor is disabled */
                                                    kPORT_PullDisable,
                                                    /* Low internal pull resistor value is selected. */
                                                    kPORT_LowPullResistor,
                                                    /* Fast slew rate is configured */
                                                    kPORT_FastSlewRate,
                                                    /* Passive input filter is disabled */
                                                    kPORT_PassiveFilterDisable,
                                                    /* Open drain output is disabled */
                                                    kPORT_OpenDrainDisable,
                                                    /* Low drive strength is configured */
                                                    kPORT_LowDriveStrength,
                                                    /* Normal drive strength is configured */
                                                    kPORT_NormalDriveStrength,
                                                    /* Pin is configured as LPSPI0_PCS0 */
                                                    kPORT_MuxAlt2,
                                                    /* Digital input enabled */
                                                    kPORT_InputBufferEnable,
                                                    /* Digital input is not inverted */
                                                    kPORT_InputNormal,
                                                    /* Pin Control Register fields [15:0] are not locked */
                                                    kPORT_UnlockRegister};
    /* PORT1_3 (pin 59) is configured as LPSPI0_PCS0 */
    PORT_SetPinConfig(PORT1, 3U, &port1_3_pin59_config);
#endif

board/Kconfig

加入SPI0相关配置

menuconfig BSP_USING_SPI
    config BSP_USING_SPI
        bool "Enable SPI"
        select RT_USING_SPI
        default y

    if BSP_USING_SPI
        config BSP_USING_SPI0
            bool "Enable SPI0"
            default 
    endif

drv_spi.c

spi驱动层修改如下

/*
 * Copyright (c) 2006-2024, RT-Thread Development Team
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Change Logs:
 * Date           Author       Notes
 * 2024-08-3      hywing       The first version for MCXA
 */
#include "rtdevice.h"
#include "drv_spi.h"
#include "fsl_common.h"
#include "fsl_lpspi.h"
#include "fsl_lpspi_edma.h"

#define DMA_MAX_TRANSFER_COUNT (32767)

enum
{
#ifdef BSP_USING_SPI0
    SPI1_INDEX,
#endif
};

struct lpc_spi
{
    struct rt_spi_bus           parent;
    LPSPI_Type                  *LPSPIx;
    clock_attach_id_t           clock_attach_id;
    clock_div_name_t            clock_div_name;
    clock_name_t                clock_name;

    DMA_Type                    *DMAx;
    uint8_t                     tx_dma_chl;
    uint8_t                     rx_dma_chl;
    edma_handle_t               dma_tx_handle;
    edma_handle_t               dma_rx_handle;
    dma_request_source_t        tx_dma_request;
    dma_request_source_t        rx_dma_request;
    lpspi_master_edma_handle_t  spi_dma_handle;

    rt_sem_t                    sem;
    char                        *name;
};


static struct lpc_spi lpc_obj[] =
{
#ifdef BSP_USING_SPI0
    {
        .LPSPIx = LPSPI0,
        .clock_attach_id = kFRO12M_to_LPSPI0,
        .clock_div_name = kCLOCK_DivLPSPI0,
        .clock_name = kCLOCK_Fro12M,
        .tx_dma_request = kDma0RequestLPSPI0Tx,
        .rx_dma_request = kDma0RequestLPSPI0Rx,
        .DMAx = DMA0,
        .tx_dma_chl = 0,
        .rx_dma_chl = 1,
        .name = "spi0",
    },
#endif
};

struct lpc_sw_spi_cs
{
    rt_uint32_t pin;
};

rt_err_t rt_hw_spi_device_attach(const char *bus_name, const char *device_name, rt_uint32_t pin)
{
    rt_err_t ret = RT_EOK;

    struct rt_spi_device *spi_device = (struct rt_spi_device *)rt_malloc(sizeof(struct rt_spi_device));
    struct lpc_sw_spi_cs *cs_pin = (struct lpc_sw_spi_cs *)rt_malloc(sizeof(struct lpc_sw_spi_cs));

    cs_pin->pin = pin;
    rt_pin_mode(pin, PIN_MODE_OUTPUT);
    rt_pin_write(pin, PIN_HIGH);

    ret = rt_spi_bus_attach_device(spi_device, device_name, bus_name, (void *)cs_pin);

    return ret;
}


static rt_err_t spi_configure(struct rt_spi_device *device, struct rt_spi_configuration *cfg)
{
    rt_err_t ret = RT_EOK;
//    struct lpc_spi *spi = RT_NULL;
//    spi = (struct lpc_spi *)(device->bus->parent.user_data);
//    ret = lpc_spi_init(spi->SPIx, cfg);
    return ret;
}


static void LPSPI_MasterUserCallback(LPSPI_Type *base, lpspi_master_edma_handle_t *handle, status_t status, void *userData)
{
    struct lpc_spi *spi = (struct lpc_spi *)userData;
    rt_sem_release(spi->sem);

}

static rt_ssize_t spixfer(struct rt_spi_device *device, struct rt_spi_message *message)
{
    int i;
    lpspi_transfer_t transfer = {0};

    RT_ASSERT(device != RT_NULL);
    RT_ASSERT(device->bus != RT_NULL);
    RT_ASSERT(device->bus->parent.user_data != RT_NULL);


    struct lpc_spi *spi = (struct lpc_spi *)(device->bus->parent.user_data);
    struct lpc_sw_spi_cs *cs = device->parent.user_data;

    if (message->cs_take)
    {
        rt_pin_write(cs->pin, PIN_LOW);
    }

    transfer.dataSize = message->length;
    transfer.rxData   = (uint8_t *)(message->recv_buf);
    transfer.txData   = (uint8_t *)(message->send_buf);

    //  if(message->length < MAX_DMA_TRANSFER_SIZE)
    if (0)
    {
        LPSPI_MasterTransferBlocking(spi->LPSPIx, &transfer);
    }
    else
    {
        uint32_t block, remain;
        block = message->length / DMA_MAX_TRANSFER_COUNT;
        remain = message->length % DMA_MAX_TRANSFER_COUNT;

        for (i = 0; i < block; i++)
        {
            transfer.dataSize = DMA_MAX_TRANSFER_COUNT;
            if (message->recv_buf) transfer.rxData   = (uint8_t *)(message->recv_buf + i * DMA_MAX_TRANSFER_COUNT);
            if (message->send_buf) transfer.txData   = (uint8_t *)(message->send_buf + i * DMA_MAX_TRANSFER_COUNT);

            LPSPI_MasterTransferEDMA(spi->LPSPIx, &spi->spi_dma_handle, &transfer);
            rt_sem_take(spi->sem, RT_WAITING_FOREVER);
        }

        if (remain)
        {
            transfer.dataSize = remain;
            if (message->recv_buf) transfer.rxData   = (uint8_t *)(message->recv_buf + i * DMA_MAX_TRANSFER_COUNT);
            if (message->send_buf) transfer.txData   = (uint8_t *)(message->send_buf + i * DMA_MAX_TRANSFER_COUNT);

            LPSPI_MasterTransferEDMA(spi->LPSPIx, &spi->spi_dma_handle, &transfer);
            rt_sem_take(spi->sem, RT_WAITING_FOREVER);
        }
    }


    if (message->cs_release)
    {
        rt_pin_write(cs->pin, PIN_HIGH);
    }

    return message->length;
}



static struct rt_spi_ops lpc_spi_ops =
{
    .configure = spi_configure,
    .xfer      = spixfer
};



int rt_hw_spi_init(void)
{
    int i;

    for (i = 0; i < ARRAY_SIZE(lpc_obj); i++)
    {
        CLOCK_SetClockDiv(lpc_obj[i].clock_div_name, 1u);
        CLOCK_AttachClk(lpc_obj[i].clock_attach_id);

        lpc_obj[i].parent.parent.user_data = &lpc_obj[i];
        lpc_obj[i].sem = rt_sem_create("sem_spi", 0, RT_IPC_FLAG_FIFO);

        lpspi_master_config_t masterConfig;
        LPSPI_MasterGetDefaultConfig(&masterConfig);
        masterConfig.baudRate = 12 * 1000 * 1000;
        masterConfig.pcsToSckDelayInNanoSec        = 1000000000U / masterConfig.baudRate * 1U;
        masterConfig.lastSckToPcsDelayInNanoSec    = 1000000000U / masterConfig.baudRate * 1U;
        masterConfig.betweenTransferDelayInNanoSec = 1000000000U / masterConfig.baudRate * 1U;

        LPSPI_MasterInit(lpc_obj[i].LPSPIx, &masterConfig, CLOCK_GetFreq(lpc_obj[i].clock_name));

        EDMA_CreateHandle(&lpc_obj[i].dma_tx_handle, lpc_obj[i].DMAx, lpc_obj[i].tx_dma_chl);
        EDMA_CreateHandle(&lpc_obj[i].dma_rx_handle, lpc_obj[i].DMAx, lpc_obj[i].rx_dma_chl);

        EDMA_SetChannelMux(lpc_obj[i].DMAx, lpc_obj[i].tx_dma_chl, lpc_obj[i].tx_dma_request);
        EDMA_SetChannelMux(lpc_obj[i].DMAx, lpc_obj[i].rx_dma_chl, lpc_obj[i].rx_dma_request);

        LPSPI_MasterTransferCreateHandleEDMA(lpc_obj[i].LPSPIx, &lpc_obj[i].spi_dma_handle, LPSPI_MasterUserCallback, &lpc_obj[i], &lpc_obj[i].dma_rx_handle, &lpc_obj[i].dma_tx_handle);

        rt_spi_bus_register(&lpc_obj[i].parent, lpc_obj[i].name, &lpc_spi_ops);
    }
    return RT_EOK;
}
INIT_DEVICE_EXPORT(rt_hw_spi_init);

SConscript

在Libraries/MCXA153/SConscript文件里边加上以下代码

if GetDepend('BSP_USING_SPI'):
    src += ['MCXA153/drivers/fsl_lpspi.c']
    src += ['MCXA153/drivers/fsl_lpspi_edma.c']

测试用例

打开menuconfig使能spi0驱动

短接MISO和MOSI引脚（P1_0和P1_2）进行自发自收测试

测试程序

#include <rtthread.h>  
#include "rtdevice.h" 
#include "drv_spi.h"

#define SPI_BUS_NAME "spi0" 
#define SPI_DEV_NAME "spi00" 

static struct rt_spi_device *spi_device;

static void spi_sample(void)  
{      
	rt_err_t result;      
	struct rt_spi_configuration cfg;    
	uint8_t tx_buf[] = "Hello RT-Thread!";      
	uint8_t rx_buf[sizeof(tx_buf)];  
	rt_base_t cs = 1*32+3;    
	rt_hw_spi_device_attach(SPI_BUS_NAME, SPI_DEV_NAME, cs);

    /* »ñÈ¡SPIÉ豸 */
    spi_device = (struct rt_spi_device *)rt_device_find(SPI_DEV_NAME);
    if (!spi_device)
    {
        rt_kprintf("can't find %s device!\n", SPI_BUS_NAME);
    }

    /* ÅäÖÃSPIÉ豸 */
    cfg.data_width = 8;
    cfg.mode = RT_SPI_MASTER | RT_SPI_MODE_0 | RT_SPI_MSB;
    cfg.max_hz = 12* 1000 * 1000;

    /* ÉèÖÃSPIÉ豸 */
    rt_spi_configure(spi_device, &cfg);    
     
	result = rt_spi_transfer(spi_device, tx_buf, rx_buf, sizeof(tx_buf));      
	if (result == sizeof(tx_buf))      
	{          
		rt_kprintf("Send: %s\n", tx_buf);          
		rt_kprintf("Received: %s\n", rx_buf);      
	}      
	else      
	{          
		rt_kprintf("spi transfer failed! error code: %d\n", result);      
	}       
}  

int main(void)  
{      
	spi_sample();      
	return 0;  
}

运行结果

总结

• 另外，你也可以安装MCUXpresso Config Tools v16，通过图形方式配置时钟树、GPIO复用
• 完整的BSP驱动代码可以在RT-Thread的仓库找到