spidev
spidev
1
https://blog.youkuaiyun.com/weixin_44498318/article/details/126563975
linux/spi/spidev.h
#include <linux/spi/spidev.h>
static const char *device = “/dev/spidev1.0”;
puts(" -D --device device to use (default /dev/spidev1.0)\n"
" -s --speed max speed (Hz)\n"
" -d --delay delay (usec)\n"
" -b --bpw bits per word \n"
" -l --loop loopback\n"
" -H --cpha clock phase\n"
" -O --cpol clock polarity\n"
" -L --lsb least significant bit first\n"
" -C --cs-high chip select active high\n"
" -3 --3wire SI/SO signals shared\n");
11
forlinx@ubuntu:~/work/OK8MP-linux-sdk$ find . -name "*spidev*"
./rootfs_ext/usr/include/linux/spi/spidev.h
./OK8MP-linux-fs/small_rootfs/usr/bin/fltest_spidev_test
./OK8MP-linux-fs/rootfs/usr/bin/fltest_spidev_test
./OK8MP-linux-kernel/include/uapi/linux/spi/spidev.h
./OK8MP-linux-kernel/include/config/spi/spidev.h
./OK8MP-linux-kernel/drivers/spi/.spidev.o.cmd
./OK8MP-linux-kernel/drivers/spi/spidev.c
./OK8MP-linux-kernel/drivers/spi/spidev.o
./OK8MP-linux-kernel/arch/x86/platform/intel-mid/device_libs/platform_mrfld_spidev.c
./OK8MP-linux-kernel/tools/spi/spidev_test.c
./OK8MP-linux-kernel/tools/spi/spidev_fdx.c
./OK8MP-linux-kernel/Documentation/spi/spidev.rst
./appsrc/forlinx-cmd/spitest/spidev_test.c
./appsrc/forlinx-cmd/spitest/spidev_test.o
./appsrc/forlinx-cmd/spitest/fltest_spidev_test
./appsrc/forlinx-cmd/spitestA/fltest_spidev_spiflash
./appsrc/forlinx-cmd/spitestA/spidev_test.c
./appsrc/forlinx-cmd/spitestA/spidev_test.o
mode
spi的四种工作模式
Mode 0 CPOL=0, CPHA=0 —>对应到这里 0b00
Mode 1 CPOL=0, CPHA=1 —>对应到这里 0b01
Mode 2 CPOL=1, CPHA=0 —>对应到这里 0b10
Mode 3 CPOL=1, CPHA=1 —>对应到这里 0b11
https://blog.youkuaiyun.com/weixin_34382392/article/details/106597462
2、spidev驱动已定义参数(arg)
SPI_MODE_0//SCLK空闲时为低电平,第一个时间沿采样
SPI_MODE_1//SCLK空闲时为高电平,第一个时间沿采样
SPI_MODE_2//SCLK空闲时为低电平,第二个时间沿采样
SPI_MODE_3//SCLK空闲时为高电平,第二个时间沿采样
SPI_CS_HIGH//片选为高
SPI_LSB_FIRST//低位数据先传输
SPI_3WIRE//三线式,输入输出数据线为一条线
SPI_LOOP//回环模式
SPI_NO_CS//没有片选信号
3、常用端口参数设置
A、设置或读取SPI工作模式:
cmd:SPI_IOC_RD_MODE / SPI_IOC_WR_MODE
arg: uint32_t *mode
eg:
mode = mode | SPI_MODE_0 | SPI_LSB_FIRST | SPI_LOOP;
ioctl(fd, SPI_IOC_RD_MODE, &mode);
ioctl(fd, SPI_IOC_WR_MODE, &mode);
B、设置或读取SPI字节读写方向:从低到高 or 从高到低
cmd:SPI_IOC_RD_LSB_FIRST / SPI_IOC_WR_LSB_FIRST
arg:uint32_t *mode = SPI_LSB_FIRST
eg:
ioctl(fd, SPI_IOC_RD_LSB_FIRST, &mode);
ioctl(fd, SPI_IOC_WR_LSB_FIRST, &mode);
C、设置或读写SPI每字节读写的位数
cmd:SPI_IOC_RD_BITS_PER_WORD / SPI_IOC_WR_BITS_PER_WORD
arg:uint8_t bits = 8;
eg:
ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits);
ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits);
D、设置或读取SPI速率
cmd:SPI_IOC_RD_MAX_SPEED_HZ / SPI_IOC_WR_MAX_SPEED_HZ
arg:uint32_t speed = 500000;//单位:Hz
eg:
ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed);
ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed);复杂的数据通信:
cmd:SPI_IOC_MESSAGE
1
#include <stdint.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/types.h>
#include <linux/spi/spidev.h>
#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
static void pabort(const char *s)
{
perror(s);
abort();
}
static const char *device = "/dev/spidev1.0";
static uint8_t mode;
static uint8_t transfer_mode;
static uint8_t bits = 8;
static uint32_t speed = 500000;
static uint16_t delay;
static void transfer(int fd)
{
int ret;
uint8_t tx[] = {
0x90, 0x00, 0x00, 0x00,0x00,0x00
};
uint8_t rx[ARRAY_SIZE(tx)] = {0, };
struct spi_ioc_transfer tr = {
.tx_buf = (unsigned long)tx,
.rx_buf = (unsigned long)rx,
.len = ARRAY_SIZE(tx),
.delay_usecs = delay,
.speed_hz = speed,
.bits_per_word = bits,
};
ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
if (ret < 1)
pabort("can't send spi message");
for (ret = 0; ret < ARRAY_SIZE(tx); ret++) {
if (!(ret % 6))
puts("");
printf("%.2X ", rx[ret]);
}
puts("");
}
static void print_usage(const char *prog)
{
printf("Usage: %s [-DsbdlHOLC3]\n", prog);
puts(" -D --device device to use (default /dev/spidev1.0)\n"
" -s --speed max speed (Hz)\n"
" -d --delay delay (usec)\n"
" -b --bpw bits per word \n"
" -l --loop loopback\n"
" -H --cpha clock phase\n"
" -O --cpol clock polarity\n"
" -L --lsb least significant bit first\n"
" -C --cs-high chip select active high\n"
" -3 --3wire SI/SO signals shared\n");
exit(1);
}
static void parse_opts(int argc, char *argv[])
{
while (1) {
static const struct option lopts[] = {
{ "device", 1, 0, 'D' },
{ "speed", 1, 0, 's' },
{ "delay", 1, 0, 'd' },
{ "bpw", 1, 0, 'b' },
{ "loop", 0, 0, 'l' },
{ "cpha", 0, 0, 'H' },
{ "cpol", 0, 0, 'O' },
{ "lsb", 0, 0, 'L' },
{ "cs-high", 0, 0, 'C' },
{ "3wire", 0, 0, '3' },
{ "no-cs", 0, 0, 'N' },
{ "ready", 0, 0, 'R' },
{ NULL, 0, 0, 0 },
};
int c;
c = getopt_long(argc, argv, "D:s:d:b:lHOLC3NR", lopts, NULL);
if (c == -1)
break;
switch (c) {
case 'D':
device = optarg;
break;
case 's':
speed = atoi(optarg);
break;
case 'd':
delay = atoi(optarg);
break;
case 'b':
bits = atoi(optarg);
break;
case 'l':
mode |= SPI_LOOP;
break;
case 'H':
mode |= SPI_CPHA;
break;
case 'O':
mode |= SPI_CPOL;
break;
case 'L':
mode |= SPI_LSB_FIRST;
break;
case 'C':
mode |= SPI_CS_HIGH;
break;
case '3':
mode |= SPI_3WIRE;
break;
case 'N':
mode |= SPI_NO_CS;
break;
case 'R':
mode |= SPI_READY;
break;
default:
print_usage(argv[0]);
break;
}
}
}
int main(int argc, char *argv[])
{
int ret = 0;
int fd;
printf("begin to test the dock of the spi flash\n");
if ((argc == 2) && ((strstr(argv[1], "help") != NULL) || argv[1] == '?')) {
print_usage(argv[0]);
}
parse_opts(argc, argv);
fd = open(device, O_RDWR);
if (fd < 0)
pabort("can't open device");
printf("spi flash SPI_IOC_WR_MODE mode=%d\n",mode);
/*
* spi mode
*/
ret = ioctl(fd, SPI_IOC_WR_MODE, &mode);
if (ret == -1)
pabort("can't set spi mode");
ret = ioctl(fd, SPI_IOC_RD_MODE, &mode);
if (ret == -1)
pabort("can't get spi mode");
printf("spi flash SPI_IOC_RD_MODE mode=%d\n",mode);
/*
* bits per word
*/
printf("spi flash SPI_IOC_WR_BITS_PER_WORD bits=%d\n",bits);
ret = ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits);
if (ret == -1)
pabort("can't set bits per word");
ret = ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits);
if (ret == -1)
pabort("can't get bits per word");
printf("spi flash SPI_IOC_RD_BITS_PER_WORD bits=%d\n",bits);
/*
* max speed hz
*/
printf("spi flash SPI_IOC_WR_MAX_SPEED_HZ speed=%d\n",speed);
ret = ioctl(fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed);
if (ret == -1)
pabort("can't set max speed hz");
ret = ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed);
if (ret == -1)
pabort("can't get max speed hz");
printf("spi flash SPI_IOC_RD_MAX_SPEED_HZ speed=%d\n",speed);
ret = ioctl(fd, SPI_IOC_RD_LSB_FIRST, &transfer_mode);
if (ret == -1)
pabort("can't get transfer mode lsb or msb ");
printf("spi transfer_mode lsb or msb: %d\n", transfer_mode);
printf("spi mode: %d\n", mode);
printf("bits per word: %d\n", bits);
printf("max speed: %d Hz (%d KHz)\n", speed, speed/1000);
transfer(fd);
close(fd);
return ret;
}
运行代码:
root@OK8MP:~# ./fltest_spidev_spiflash
begin to test the dock of the spi flash
spi flash SPI_IOC_WR_MODE mode=0
spi flash SPI_IOC_RD_MODE mode=0
spi flash SPI_IOC_WR_BITS_PER_WORD bits=8
spi flash SPI_IOC_RD_BITS_PER_WORD bits=8
spi flash SPI_IOC_WR_MAX_SPEED_HZ speed=500000
spi flash SPI_IOC_RD_MAX_SPEED_HZ speed=500000
spi transfer_mode lsb or msb: 0
spi mode: 0
bits per word: 8
max speed: 500000 Hz (500 KHz)
00 00 00 00 51 14
参考链接:
https://blog.youkuaiyun.com/wowocpp/article/details/79786309
代码位置:
/home/forlinx/work/OK8MP-linux-sdk/appsrc/forlinx-cmd/spitestA