adxl345spi驱动

ADXL345是一款数字三轴加速度计，SPI是其一种通信协议。下面是ADXL345 SPI驱动的基本流程：

1. 配置SPI接口，设置通信速率、数据位数等参数。

2. 初始化ADXL345，设置相应的寄存器，如数据输出速率、测量范围等。

3. 通过SPI接口读取ADXL345的数据，可以读取加速度数据、温度数据等。

4. 对读取的数据进行处理，得到实际的加速度值。

下面是一个ADXL345 SPI驱动的示例代码，仅供参考：

#include <linux/spi/spi.h>
#include <linux/delay.h>

#define ADXL345_REG_ID 0x00
#define ADXL345_REG_DATAX0 0x32
#define ADXL345_REG_POWER_CTL 0x2D
#define ADXL345_POWER_ON 0x08
#define ADXL345_MEASURE_MODE 0x08
#define ADXL345_RANGE_2G 0x00
#define ADXL345_RATE_100 0x0A

static struct spi_device *spi_dev;
static struct spi_transfer xfer[2];
static struct spi_message msg;

static u8 adxl345_read_reg(u8 reg)
{
    u8 buf[2] = {reg, 0};
    spi_message_init(&msg);
    xfer[0].tx_buf = buf;
    xfer[0].len = 1;
    xfer[1].rx_buf = buf+1;
    xfer[1].len = 1;
    spi_message_add_tail(&xfer[0], &msg);
    spi_message_add_tail(&xfer[1], &msg);
    spi_sync(spi_dev, &msg);
    return buf[1];
}

static void adxl345_write_reg(u8 reg, u8 value)
{
    u8 buf[2] = {reg | 0x40, value};
    spi_message_init(&msg);
    xfer[0].tx_buf = buf;
    xfer[0].len = 2;
    spi_message_add_tail(&xfer[0], &msg);
    spi_sync(spi_dev, &msg);
}

static int adxl345_init(void)
{
    u8 id;
    id = adxl345_read_reg(ADXL345_REG_ID);
    if (id != 0xE5)
        return -ENODEV;
    adxl345_write_reg(ADXL345_REG_POWER_CTL, ADXL345_POWER_ON);
    adxl345_write_reg(ADXL345_REG_POWER_CTL, ADXL345_MEASURE_MODE);
    adxl345_write_reg(0x31, 0x00);
    adxl345_write_reg(0x2C, ADXL345_RANGE_2G);
    adxl345_write_reg(0x2C, ADXL345_RATE_100);
    return 0;
}

static int adxl345_read_xyz(int *x, int *y, int *z)
{
    u8 buf[7];
    spi_message_init(&msg);
    xfer[0].tx_buf = &buf[0];
    xfer[0].len = 1;
    xfer[1].rx_buf = &buf[1];
    xfer[1].len = 6;
    spi_message_add_tail(&xfer[0], &msg);
    spi_message_add_tail(&xfer[1], &msg);
    spi_sync(spi_dev, &msg);
    *x = (int)(buf[2] << 8 | buf[1]);
    *y = (int)(buf[4] << 8 | buf[3]);
    *z = (int)(buf[6] << 8 | buf[5]);
    return 0;
}

static int __init adxl345_spi_init(void)
{
    struct spi_master *master;
    int ret;
    master = spi_busnum_to_master(1);
    if (!master) {
        printk(KERN_ERR "spi_busnum_to_master failed\n");
        return -EINVAL;
    }
    spi_dev = spi_new_device(master, NULL);
    if (!spi_dev) {
        printk(KERN_ERR "spi_new_device failed\n");
        return -EINVAL;
    }
    spi_dev->bits_per_word = 8;
    spi_dev->mode = SPI_MODE_0;
    spi_dev->max_speed_hz = 10000000; // 10MHz
    ret = spi_setup(spi_dev);
    if (ret < 0) {
        printk(KERN_ERR "spi_setup failed\n");
        return ret;
    }
    ret = adxl345_init();
    if (ret < 0) {
        printk(KERN_ERR "adxl345_init failed\n");
        return ret;
    }
    printk(KERN_INFO "ADXL345 SPI driver initialized\n");
    return 0;
}

static void __exit adxl345_spi_exit(void)
{
    spi_unregister_device(spi_dev);
    printk(KERN_INFO "ADXL345 SPI driver exited\n");
}

module_init(adxl345_spi_init);
module_exit(adxl345_spi_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your name");
MODULE_DESCRIPTION("ADXL345 SPI driver");

注意：以上代码仅供参考，具体实现可能需要根据实际情况进行修改。