AM5728 arm端 spi调试设备树方式

一、spi管脚定义的查找

1、硬件的连接

2、根据硬件的连接从芯片手册中查找管脚的定义

根据控制寄存器跳转到相应的管脚定义，查看管脚的复用功能

二、设备树修改

在dra7.dtsi中添加spi的设备地址

mcspi2: spi@4809a000 {
           compatible = "ti,omap4-mcspi";
           reg = <0x4809a000 0x200>;
           interrupts = <GIC_SPI 61 IRQ_TYPE_LEVEL_HIGH>;
           #address-cells = <1>;
           #size-cells = <0>;
           ti,hwmods = "mcspi2";
           ti,spi-num-cs = <2>;
           dmas = <&sdma_xbar 43>,
           <&sdma_xbar 44>,
           <&sdma_xbar 45>,
           <&sdma_xbar 46>;
           dma-names = "tx0", "rx0", "tx1", "rx1";
           status = "disabled";
       };

在am57xx-beagle-x15-common.dtsi 和am57xx-evm-common.dtsi中对spi端口进行描述，理论是在某一个文件描述即可，这里没太多验证，两个都添加了

&mcspi2 {
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&spi2_pins>;
   spidev0:spi@0 {
       compatible = "spidev";
       reg = <0>;           // CS0
       spi-max-frequency = <4000000>;
   };
};

spi2_pins: spi2_pins {
       pinctrl-single,pins = <
           DRA7XX_CORE_IOPAD(0x37c0, (INPUT_EN | MUX_MODE0)) /* spi2_sclk.spi2_sclk (A26) */
           DRA7XX_CORE_IOPAD(0x37c4, (INPUT_EN | MUX_MODE0)) /* spi2_d1.spi2_d1 (B22) */
           DRA7XX_CORE_IOPAD(0x37c8, (INPUT_EN | MUX_MODE0)) /* spi2_d0.spi2_d0 (G17) */
           DRA7XX_CORE_IOPAD(0x37cc, (PIN_OUTPUT_PULLUP | MUX_MODE0)) /* spi2_cs0.spi2_cs0 (B24) */
       >;
   };

然后编译设备树dtb文件和内核zImage

内核中选中spidev

Device Drivers --->
[*] SPI support --->
<*> User Mode SPI device driver support

三、测试应用程序使用内存代码中的测试程序即可路径Documentation/spi下的spidev_test.c

/*
* SPI testing utility (using spidev driver)
*
* Copyright (c) 2007 MontaVista Software, Inc.
* Copyright (c) 2007 Anton Vorontsov <avorontsov@ru.mvista.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License.
*
* Cross-compile with cross-gcc -I/path/to/cross-kernel/include
*/

#include <stdint.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.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/spidev1.1";
static uint32_t mode;
static uint8_t bits = 8;
static uint32_t speed = 500000;
static uint16_t delay;
static int verbose;

uint8_t default_tx[] = {
   0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
   0x40, 0x00, 0x00, 0x00, 0x00, 0x95,
   0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
   0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
   0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
   0xF0, 0x0D,
};

uint8_t default_rx[ARRAY_SIZE(default_tx)] = {0, };
char *input_tx;

static void hex_dump(const void *src, size_t length, size_t line_size, char *prefix)
{
   int i = 0;
   const unsigned char *address = src;
   const unsigned char *line = address;
   unsigned char c;

printf("%s | ", prefix);
   while (length-- > 0) {
       printf("%02X ", *address++);
       if (!(++i % line_size) || (length == 0 && i % line_size)) {
           if (length == 0) {
               while (i++ % line_size)
                   printf("__ ");
           }
           printf(" | "); /* right close */
           while (line < address) {
               c = *line++;
               printf("%c", (c < 33 || c == 255) ? 0x2E : c);
           }
           printf("\n");
           if (length > 0)
               printf("%s | ", prefix);
       }
   }
}

/*
* Unescape - process hexadecimal escape character
* converts shell input "\x23" -> 0x23
*/
static int unescape(char *_dst, char *_src, size_t len)
{
   int ret = 0;
   char *src = _src;
   char *dst = _dst;
   unsigned int ch;

while (*src) {
       if (*src == '\\' && *(src+1) == 'x') {
           sscanf(src + 2, "%2x", &ch);
           src += 4;
           *dst++ = (unsigned char)ch;
       } else {
           *dst++ = *src++;
       }
       ret++;
   }
   return ret;
}

static void transfer(int fd, uint8_t const *tx, uint8_t const *rx, size_t len)
{
int ret;

struct spi_ioc_transfer tr = {
       .tx_buf = (unsigned long)tx,
       .rx_buf = (unsigned long)rx,
       .len = len,
       .delay_usecs = delay,
       .speed_hz = speed,
       .bits_per_word = bits,
   };

if (mode & SPI_TX_QUAD)
       tr.tx_nbits = 4;
   else if (mode & SPI_TX_DUAL)
       tr.tx_nbits = 2;
   if (mode & SPI_RX_QUAD)
       tr.rx_nbits = 4;
   else if (mode & SPI_RX_DUAL)
       tr.rx_nbits = 2;
   if (!(mode & SPI_LOOP)) {
       if (mode & (SPI_TX_QUAD | SPI_TX_DUAL))
           tr.rx_buf = 0;
       else if (mode & (SPI_RX_QUAD | SPI_RX_DUAL))
           tr.tx_buf = 0;
   }

ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);
if (ret < 1)
pabort("can't send spi message");

if (verbose)
hex_dump(tx, len, 32, "TX");
hex_dump(rx, len, 32, "RX");
}

static void print_usage(const char *prog)
{
   printf("Usage: %s [-DsbdlHOLC3]\n", prog);
   puts(" -D --device device to use (default /dev/spidev1.1)\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"
   " -v --verbose Verbose (show tx buffer)\n"
   " -p Send data (e.g. \"1234\\xde\\xad\")\n"
   " -N --no-cs no chip select\n"
   " -R --ready slave pulls low to pause\n"
   " -2 --dual dual transfer\n"
   " -4 --quad quad transfer\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' },
           { "dual", 0, 0, '2' },
           { "verbose", 0, 0, 'v' },
           { "quad", 0, 0, '4' },
           { NULL, 0, 0, 0 },
       };
       int c;

c = getopt_long(argc, argv, "D:s:d:b:lHOLC3NR24p:v", 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 'v':
           verbose = 1;
           break;
       case 'R':
           mode |= SPI_READY;
           break;
       case 'p':
           input_tx = optarg;
           break;
       case '2':
           mode |= SPI_TX_DUAL;
           break;
       case '4':
           mode |= SPI_TX_QUAD;
           break;
       default:
           print_usage(argv[0]);
           break;
       }
   }
   if (mode & SPI_LOOP) {
       if (mode & SPI_TX_DUAL)
           mode |= SPI_RX_DUAL;
       if (mode & SPI_TX_QUAD)
           mode |= SPI_RX_QUAD;
   }
}

int main(int argc, char *argv[])
{
   int ret = 0;
   int fd;
   uint8_t *tx;
   uint8_t *rx;
   int size;

parse_opts(argc, argv);

fd = open(device, O_RDWR);
if (fd < 0)
pabort("can't open device");

/*
   * spi mode
   */
   ret = ioctl(fd, SPI_IOC_WR_MODE32, &mode);
   if (ret == -1)
       pabort("can't set spi mode");

ret = ioctl(fd, SPI_IOC_RD_MODE32, &mode);
if (ret == -1)
pabort("can't get spi mode");

/*
   * bits per word
   */
   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");

/*
   * max speed hz
   */
   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 mode: 0x%x\n", mode);
printf("bits per word: %d\n", bits);
printf("max speed: %d Hz (%d KHz)\n", speed, speed/1000);

if (input_tx) {
       size = strlen(input_tx+1);
       tx = malloc(size);
       rx = malloc(size);
       size = unescape((char *)tx, input_tx, size);
       transfer(fd, tx, rx, size);
       free(rx);
       free(tx);
   } else {
       transfer(fd, default_tx, default_rx, sizeof(default_tx));
   }

close(fd);

return ret;
}

四、测试方法

将D0与D1短接

在 /dev下查看到spidev1.0设备

然后在系统终端输入spidev_test -D /dev/spidev1.0

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