linux spi驱动编写

#include <linux/module.h>
#include <linux/spi/spidev.h>
#include <linux/fs.h>
#include <linux/cdev.h>

static struct spi_device *spi_dev;
static struct cdev cdev;
static dev_t dev_num;

static int spi_open(struct inode *inode, struct file *file) {
    return 0;
}

static int spi_release(struct inode *inode, struct file *file) {
    return 0;
}

static ssize_t spi_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) {
    u8 tx[] = {0x01, 0x80, 0x00};
    u8 rx[3];
    int ret;

    ret = spi_sync_transfer(spi_dev, tx, rx, sizeof(tx));
    if (ret < 0) {
        return ret;
    }

    if (copy_to_user(buf, rx, sizeof(rx))) {
        return -EFAULT;
    }

    return sizeof(rx);
}

static ssize_t spi_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) {
    u8 tx[3];
    int ret;

    if (copy_from_user(tx, buf, count)) {
        return -EFAULT;
    }

    ret = spi_sync_transfer(spi_dev, tx, NULL, count);
    if (ret < 0) {
        return ret;
    }

    return count;
}

static struct file_operations spi_fops = {
    .owner = THIS_MODULE,
    .open = spi_open,
    .release = spi_release,
    .read = spi_read,
    .write = spi_write,
};

static int __init spi_init(void) {
    int ret;

    ret = alloc_chrdev_region(&dev_num, 0, 1, "spi_device");
    if (ret < 0) {
        return ret;
    }

    cdev_init(&cdev, &spi_fops);
    cdev.owner = THIS_MODULE;
    ret = cdev_add(&cdev, dev_num, 1);
    if (ret < 0) {
        unregister_chrdev_region(dev_num, 1);
        return ret;
    }

    spi_dev = spi_alloc_device(&spi_master);
    if (!spi_dev) {
        cdev_del(&cdev);
        unregister_chrdev_region(dev_num, 1);
        return -ENOMEM;
    }

    spi_dev->mode = SPI_MODE_0;
    spi_dev->max_speed_hz = 500000;
    spi_dev->bits_per_word = 8;

    ret = spi_add_device(spi_master, spi_dev);
    if (ret < 0) {
        spi_dev_put(spi_dev);
        cdev_del(&cdev);
        unregister_chrdev_region(dev_num, 1);
        return ret;
    }

    return 0;
}

static void __exit spi_exit(void) {
    spi_remove_device(spi_dev);
    spi_dev_put(spi_dev);
    cdev_del(&cdev);
    unregister_chrdev_region(dev_num, 1);
}

module_init(spi_init);
module_exit(spi_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Your Name");
MODULE_DESCRIPTION("A simple SPI driver");