sdk 目前還不支持 spi，沒有 spi 就失去了很多樂趣，如 easyflash、spi 的屏幕，藍(lán)訊的這次活動(dòng)我接到了模擬 spi 的任務(wù)，下面介紹如何寫 rt-thread 的設(shè)備驅(qū)動(dòng)層的驅(qū)動(dòng)。（rt-thread的設(shè)備 I/O 模型有設(shè)備管理層、設(shè)備驅(qū)動(dòng)框架層、設(shè)備驅(qū)動(dòng)層），我寫過一篇使用 timer 的，就屬于最接近用戶那一層-設(shè)備管理層，我們調(diào)用 rt_device_find 根據(jù)名稱查找句柄，之后根據(jù)句柄執(zhí)行 rt_device_read、rt_device_write、rt_device_control 語(yǔ)句完成與底層設(shè)備的交互，而最底層的 timer 已經(jīng)由中科藍(lán)訊的工程師完成了。而這次的模擬 spi 則是寫設(shè)備驅(qū)動(dòng)層。

設(shè)備驅(qū)動(dòng)層的編寫有兩步：

實(shí)現(xiàn) spi 的驅(qū)動(dòng)程序（模擬 spi 主要通過 io 口模擬 spi 的時(shí)序）將裸機(jī)程序按 rt-thread 的設(shè)備驅(qū)動(dòng)框架封裝（主要是自己寫的函數(shù)原型與 rt-thread 的接口對(duì)應(yīng)上）

在 library 下添加 drv_soft_spi.c 和 drv_soft_spi.h

3.1 drv_soft_spi.c
/*
* Change Logs:
* Date Author Notes
* 2021-06-03 qwz first version
*/
#include "board.h"
#ifdef RT_USING_SPI
#ifdef RT_SPI_SOFT
#include "spi.h"
#include "drv_soft_spi.h"
#include 
#define DRV_DEBUG
#define LOG_TAG "drv.spisoft"
#include 
enum{
#ifdef BSP_USING_SOFT_SPI1
 SOFT_SPI1_INDEX,
#endif
};
//PB2 10 ;PE5 18;PE6 19;PB1 9;
#define SOFT_SPI1_BUS_CONFIG { \
 .mosi_pin = 18, \
 .miso_pin = 10, \
 .sclk_pin = 9, \
 .bus_name = "spi0", \ }
static struct ab32_soft_spi_config soft_spi_config[] ={
#ifdef BSP_USING_SOFT_SPI1
 SOFT_SPI1_BUS_CONFIG,
#endif
};
static struct ab32_soft_spi soft_spi_bus_obj[sizeof(soft_spi_config) / sizeof(soft_spi_config[0])] = {0};
static rt_err_t ab32_spi_init(struct ab32_soft_spi *spi_drv, struct rt_spi_configuration *cfg){
 RT_ASSERT(spi_drv != RT_NULL);
 RT_ASSERT(cfg != RT_NULL);
//mode = master
 if (cfg->mode & RT_SPI_SLAVE){
return RT_EIO;
 }
else
spi_drv->mode = RT_SPI_MASTER;
 if (cfg->mode & RT_SPI_3WIRE){
 return RT_EIO;
 }
 if (cfg->data_width == 8 || cfg->data_width == 16)
spi_drv->data_width = cfg->data_width;
else{
 return RT_EIO;
 }
 if (cfg->mode & RT_SPI_CPHA){
spi_drv->cpha = 1;
 }
 else{
 spi_drv->cpha = 0;
 }
 if (cfg->mode & RT_SPI_CPOL){
spi_drv->cpol = 1;
 }
 else{
 spi_drv->cpol = 0;
 }
 if (cfg->mode & RT_SPI_NO_CS){
 }
 else{
 }
 if (cfg->max_hz >= 1200000){
spi_drv->spi_delay = 0;
 }else if (cfg->max_hz >= 1000000){
 spi_drv->spi_delay = 8;
 }else if (cfg->max_hz >= 830000){
 spi_drv->spi_delay = 16;
 }
 else {
 spi_drv->spi_delay = 24;
 }
 LOG_D("SPI limiting freq: %d, BaudRatePrescaler: %d",
 cfg->max_hz,
 spi_drv->max_hz);
 if (cfg->mode & RT_SPI_MSB){
spi_drv->msb = 1;
 }
 else{
 spi_drv->msb = 0;
 }
 rt_pin_mode(spi_drv->config->mosi_pin,PIN_MODE_OUTPUT_OD);
 rt_pin_write(spi_drv->config->mosi_pin,PIN_HIGH);
 rt_pin_mode(spi_drv->config->miso_pin,PIN_MODE_INPUT_PULLDOWN);
 rt_pin_mode(spi_drv->config->sclk_pin,PIN_MODE_OUTPUT_OD);
if(spi_drv->cpol)
 rt_pin_write(spi_drv->config->sclk_pin,PIN_HIGH);
else
 rt_pin_write(spi_drv->config->sclk_pin,PIN_LOW);
 LOG_D("%s init done", spi_drv->config->bus_name);
 return RT_EOK;
}
static inline void spi_delay(rt_uint32_t us){
 rt_thread_mdelay(us);
}
static rt_uint32_t soft_spi_read_write_bytes(struct ab32_soft_spi *spi_drv, rt_uint8_t* send_buff, 
rt_uint8_t* recv_buff, rt_uint32_t len){
rt_uint8_t dataIndex = 0;
rt_uint8_t time = 1;
for(rt_uint32_t i = 0; icpha){ //CPHA=1
 if(rt_pin_read(spi_drv->config->sclk_pin))
 {
 rt_pin_write(spi_drv->config->sclk_pin,PIN_LOW);
 }
 else {
 rt_pin_write(spi_drv->config->sclk_pin,PIN_HIGH);
 } }
if(spi_drv->data_width == 16)
time = 2;
do{
for(rt_uint8_t j = 0; j < 8; j++){
if ((send_buff[dataIndex] & 0x80) != 0){
 rt_pin_write(spi_drv->config->mosi_pin,PIN_HIGH);
}else{
 rt_pin_write(spi_drv->config->mosi_pin,PIN_LOW);
}
send_buff[dataIndex] <<= 1;
spi_delay(spi_drv->spi_delay);
 if(rt_pin_read(spi_drv->config->sclk_pin))
 {
 rt_pin_write(spi_drv->config->sclk_pin,PIN_LOW);
 }
 else {
 rt_pin_write(spi_drv->config->sclk_pin,PIN_HIGH);
 }
recv_buff[dataIndex] <<= 1;
if (rt_pin_read(spi_drv->config->miso_pin))
recv_buff[dataIndex] |= 0x01;
spi_delay(spi_drv->spi_delay);
if(time != 0 || j != 7){
 if(rt_pin_read(spi_drv->config->sclk_pin))
 {
 rt_pin_write(spi_drv->config->sclk_pin,PIN_LOW);
 }
 else {
 rt_pin_write(spi_drv->config->sclk_pin,PIN_HIGH);
 } } }
dataIndex++;
}while((--time)==1);
time = 1;
spi_delay(spi_drv->spi_delay);
}
 return len;
}
static rt_uint32_t soft_spi_read_bytes(struct ab32_soft_spi *spi_drv, rt_uint8_t* recv_buff, rt_uint32_t 
len){
rt_uint8_t send_buff = spi_drv->dummy_data;
rt_uint32_t dataIndex = 0;
rt_uint8_t time = 1;
if(spi_drv->cpha){ //CPHA=1
 if(rt_pin_read(spi_drv->config->sclk_pin))
 {
 rt_pin_write(spi_drv->config->sclk_pin,PIN_LOW);
 }
 else {
 rt_pin_write(spi_drv->config->sclk_pin,PIN_HIGH);
 } }
for(rt_uint32_t i = 0; idata_width == 16)
time = 2;
do{
for(rt_uint8_t j = 0; j < 8; j++){
if ((send_buff & 0x80) != 0){
rt_pin_write(spi_drv->config->mosi_pin,PIN_HIGH);
}else{
rt_pin_write(spi_drv->config->mosi_pin,PIN_LOW);
}
send_buff <<= 1;
spi_delay(spi_drv->spi_delay);
 if(rt_pin_read(spi_drv->config->sclk_pin))
 {
 rt_pin_write(spi_drv->config->sclk_pin,PIN_LOW);
 }
 else {
 rt_pin_write(spi_drv->config->sclk_pin,PIN_HIGH);
 }
 *recv_buff <<= 1;
if (rt_pin_read(spi_drv->config->miso_pin))
{
*recv_buff |= 0x01;
}
else
{
*recv_buff &= 0xfe;
}
spi_delay(spi_drv->spi_delay);
if(time != 0 || j != 7){
 if(rt_pin_read(spi_drv->config->sclk_pin))
 {
 rt_pin_write(spi_drv->config->sclk_pin,PIN_LOW);
 }
 else {
 rt_pin_write(spi_drv->config->sclk_pin,PIN_HIGH);
 } } }
recv_buff ++;
dataIndex++;
}while((--time)==1);
time = 1;
spi_delay(spi_drv->spi_delay);
LOG_D("DONE ONE BYTE %d",dataIndex);
LOG_D("%d",spi_drv->spi_delay);
}
 return len;
}
static rt_uint32_t soft_spi_write_bytes(struct ab32_soft_spi *spi_drv, rt_uint8_t* send_buff, rt_uint32_t 
len){
rt_uint8_t recv_buff = 0;
rt_uint32_t dataIndex = 0;
rt_uint8_t time = 1;
LOG_D("%x",send_buff[0]);
if(spi_drv->cpha){ //CPHA=1
 if(rt_pin_read(spi_drv->config->sclk_pin))
 {
 rt_pin_write(spi_drv->config->sclk_pin,PIN_LOW);
 }
 else {
 rt_pin_write(spi_drv->config->sclk_pin,PIN_HIGH);
 } }
for(uint32_t i = 0; idata_width == 16)
time = 2;
do{
for(rt_uint8_t j = 0; j < 8; j++){
if ((send_buff[dataIndex] & 0x80) != 0){
rt_pin_write(spi_drv->config->mosi_pin,PIN_HIGH);
LOG_D("PIN_HIGH");
}else{
rt_pin_write(spi_drv->config->mosi_pin,PIN_LOW);
LOG_D("PIN_LOW");
}
send_buff[dataIndex] <<= 1;
spi_delay(spi_drv->spi_delay);
 if(rt_pin_read(spi_drv->config->sclk_pin))
 {
 rt_pin_write(spi_drv->config->sclk_pin,PIN_LOW);
 }
 else {
 rt_pin_write(spi_drv->config->sclk_pin,PIN_HIGH);
 }
recv_buff <<= 1;
if (rt_pin_read(spi_drv->config->miso_pin))
recv_buff |= 0x01;
spi_delay(spi_drv->spi_delay);
if(time != 0 || j != 7){
 if(rt_pin_read(spi_drv->config->sclk_pin))
 {
 rt_pin_write(spi_drv->config->sclk_pin,PIN_LOW);
 }
 else {
 rt_pin_write(spi_drv->config->sclk_pin,PIN_HIGH);
 } } }
dataIndex++;
}while((--time)==1);
time = 1;
spi_delay(spi_drv->spi_delay);
}
 return len;
}
static rt_uint32_t spixfer(struct rt_spi_device *device, struct rt_spi_message *message){
 rt_uint32_t state;
 rt_size_t message_length;
 rt_uint8_t *recv_buf;
 const rt_uint8_t *send_buf;
 rt_uint8_t pin = rt_pin_get("PE.6");
 RT_ASSERT(device != RT_NULL);
 RT_ASSERT(device->bus != RT_NULL);
 RT_ASSERT(device->bus->parent.user_data != RT_NULL);
 RT_ASSERT(message != RT_NULL);
 struct ab32_soft_spi *spi_drv = rt_container_of(device->bus, struct ab32_soft_spi, spi_bus);
 struct ab32_soft_spi_pin *cs = device->parent.user_data;
 if (message->cs_take){
 rt_pin_write(cs->GPIO_Pin,PIN_LOW);
 }
 LOG_D("%s transfer prepare and start", spi_drv->config->bus_name);
 LOG_D("%s sendbuf: %02x, recvbuf: %02x, length: %d",
 spi_drv->config->bus_name,
 (message->send_buf),
 ((rt_uint8_t *)(message->recv_buf)), message->length);
 message_length = message->length;
 recv_buf = message->recv_buf;
 send_buf = message->send_buf;
 if(message_length){
 if (message->send_buf && message->recv_buf){
 state = soft_spi_read_write_bytes(spi_drv, (rt_uint8_t *)send_buf, (rt_uint8_t *)recv_buf, 
message_length);
 LOG_D("soft_spi_read_write_bytes");
 }
 else if (message->send_buf){
 state = soft_spi_write_bytes(spi_drv, (rt_uint8_t *)send_buf, message_length);
 LOG_D("soft_spi_write_bytes");
 }
 else{
 memset((rt_uint8_t *)recv_buf, 0x00, message_length);
 state = soft_spi_read_bytes(spi_drv, (rt_uint8_t *)recv_buf, message_length);
 LOG_D("soft_spi_read_bytes");
 }
 if (state != message_length){
 LOG_I("spi transfer error : %d", state);
 message->length = 0;
 }
 else{
 LOG_D("%s transfer done", spi_drv->config->bus_name);
 }
 }
 if (message->cs_release){
 rt_pin_write(cs->GPIO_Pin,PIN_HIGH);
 }
 return message->length;
}
static rt_err_t spi_configure(struct rt_spi_device *device,
 struct rt_spi_configuration *configuration){
 RT_ASSERT(device != RT_NULL);
 RT_ASSERT(configuration != RT_NULL);
 struct ab32_soft_spi *spi_drv = rt_container_of(device->bus, struct ab32_soft_spi, spi_bus);
 spi_drv->cfg = configuration;
 return ab32_spi_init(spi_drv, configuration);
}
static const struct rt_spi_ops ab32_spi_ops ={
 .configure = spi_configure,
 .xfer = spixfer,
};
static int rt_soft_spi_bus_init(void){
 rt_err_t result;
 for (int i = 0; i < sizeof(soft_spi_config) / sizeof(soft_spi_config[0]); i++){
 soft_spi_bus_obj[i].config = &soft_spi_config[i];
 soft_spi_bus_obj[i].spi_bus.parent.user_data = &soft_spi_config[i];
 result = rt_spi_bus_register(&soft_spi_bus_obj[i].spi_bus, soft_spi_config[i].bus_name, 
&ab32_spi_ops);
 RT_ASSERT(result == RT_EOK);
 LOG_D("%s bus init done", soft_spi_config[i].bus_name);
 }
 return result;
}
/**
 * Attach the spi device to SPI bus, this function must be used after initialization.
 */
rt_err_t rt_soft_spi_device_attach(const char *bus_name, const char *device_name, hal_sfr_t cs_gpiox, 
rt_uint8_t cs_gpio_pin){
 RT_ASSERT(bus_name != RT_NULL);
 RT_ASSERT(device_name != RT_NULL);
 rt_err_t result;
 struct rt_spi_device *spi_device;
 struct ab32_soft_spi_pin *cs_pin;
 /* attach the device to spi bus*/
 spi_device = (struct rt_spi_device *)rt_malloc(sizeof(struct rt_spi_device));
 RT_ASSERT(spi_device != RT_NULL);
 cs_pin = (struct ab32_soft_spi_pin *)rt_malloc(sizeof(struct ab32_soft_spi_pin));
 RT_ASSERT(cs_pin != RT_NULL);
 cs_pin->GPIOx = cs_gpiox;
 cs_pin->GPIO_Pin = cs_gpio_pin;
 rt_pin_mode(cs_pin->GPIO_Pin, PIN_MODE_OUTPUT);
 result = rt_spi_bus_attach_device(spi_device, device_name, bus_name, (void *)cs_pin);
 if (result != RT_EOK){
 LOG_E("%s attach to %s faild, %d\n", device_name, bus_name, result);
 }
 RT_ASSERT(result == RT_EOK);
 LOG_D("%s attach to %s done", device_name, bus_name);
 return result;
}
int rt_soft_spi_init(void){
 return rt_soft_spi_bus_init();
}
INIT_BOARD_EXPORT(rt_soft_spi_init);
#endif
#endif /* RT_USING_SPI */;>;>;>

審核編輯 黃昊宇