linux spi 设备驱动

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

#define DEVICE_NAME "my_spi_device"
#define CLASS_NAME "my_spi_class"

static int major_number;
static struct class* my_spi_class = NULL;
static struct device* my_spi_device = NULL;

static ssize_t spi_read(struct file *filp, char __user *buffer, size_t length, loff_t *offset) {
    struct spi_device *spi;
    struct spi_transfer t;
    struct spi_message m;
    unsigned char tx_buf[1] = {0x01};
    unsigned char rx_buf[1];
    int ret;

    spi = container_of(filp->private_data, struct spi_device, dev);
    memset(&t, 0, sizeof(t));
    t.tx_buf = &tx_buf[0];
    t.rx_buf = &rx_buf[0];
    t.len = 1;

    spi_message_init(&m);
    spi_message_add_tail(&t, &m);

    ret = spi_sync(spi, &m);
    if (ret < 0) {
        printk(KERN_ALERT "SPI read failed
");
        return ret;
    }

    if (copy_to_user(buffer, &rx_buf[0], length)) {
        return -EFAULT;
    }
    return length;
}

static ssize_t spi_write(struct file *filp, const char __user *buffer, size_t length, loff_t *offset) {
    // 类似读操作的实现，这里省略
    return 0;
}

static struct file_operations fops = {
   .read = spi_read,
   .write = spi_write,
};

static int __init spi_init(void) {
    major_number = register_chrdev(0, DEVICE_NAME, &fops);
    if (major_number < 0) {
        printk(KERN_ALERT "Failed to register device
");
        return major_number;
    }
    my_spi_class = class_create(THIS_MODULE, CLASS_NAME);
    if (IS_ERR(my_spi_class)) {
        unregister_chrdev(major_number, DEVICE_NAME);
        printk(KERN_ALERT "Failed to create class
");
        return PTR_ERR(my_spi_class);
    }
    my_spi_device = device_create(my_spi_class, NULL, MKDEV(major_number, 0), NULL, DEVICE_NAME);
    if (IS_ERR(my_spi_device)) {
        class_destroy(my_spi_class);
        unregister_chrdev(major_number, DEVICE_NAME);
        printk(KERN_ALERT "Failed to create device
");
        return PTR_ERR(my_spi_device);
    }
    return 0;
}

static void __exit spi_exit(void) {
    device_destroy(my_spi_class, MKDEV(major_number, 0));
    class_destroy(my_spi_class);
    unregister_chrdev(major_number, DEVICE_NAME);
}

module_init(spi_init);
module_exit(spi_exit);

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