驱动开发-day10

驱动代码：

#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/gpio.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/of_irq.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
struct cdev* cdev;
unsigned int major = 500;
unsigned int minor = 0;
dev_t devno;
struct class* cls;
struct device* dev;

struct resource* res;
unsigned int irqno;
struct gpio_desc* gpiono;

unsigned int number;
// 定义等待队列头
wait_queue_head_t wq_head;
unsigned int condition = 0;

ssize_t mycdev_read(struct file* file, char* ubuf, size_t size, loff_t* lof)
{
    int ret;
    // 将进程切换到休眠状态
    wait_event_interruptible(wq_head, condition);

    if (size > sizeof(number)) {
        size = sizeof(number);
    }

    ret = copy_to_user(ubuf, &number, size);
    if (ret) {
        printk("copy_to_user filed\n");
        return -EIO;
    }
    condition = 0; // 下次硬件的数据没有准备好
    return size;
}
irqreturn_t myirq_led_handler(int irqno, void* dev_id)
{

    gpiod_set_value(gpiono, !gpiod_get_value(gpiono));
    number = gpiod_get_value(gpiono);
    condition = 1; // 数据准备就绪
    // 唤醒休眠的进程
    wake_up_interruptible(&wq_head);

    return IRQ_HANDLED;
}

struct file_operations fops = {

    .read = mycdev_read,

};
int pdrv_probe(struct platform_device* pdev)
{

    int ret, i;
    // 初始化等待队列头
    init_waitqueue_head(&wq_head);
    // 分配字符设备驱动对象空间
    cdev = cdev_alloc();
    if (cdev == NULL) {
        printk("申请字符设备驱动空间失败\n");
        ret = -EFAULT;
        goto out1;
    }
    // 字符设备驱动对象部分初始化
    cdev_init(cdev, &fops);
    // 静态申请设备号
    if (major > 0) {

        ret = register_chrdev_region(MKDEV(major, minor), 3, "mykey");
        if (ret) {
            printk("静态指定设备号失败\n");
            goto out2;
        }
    } else { // 动态申请设备号
        ret = alloc_chrdev_region(&devno, minor, 3, "mykey");
        if (ret) {
            printk("动态指定设备号失败\n");
            goto out2;
        }
        major = MAJOR(devno);
        minor = MINOR(devno);
    }
    // 注册字符设备驱动对象
    ret = cdev_add(cdev, MKDEV(major, minor), 3);
    if (ret) {
        printk("注册字符设备驱动对象失败\n");
        goto out3;
    }
    printk("注册字符设备驱动对象成功\n");
    // 向上提交目录
    cls = class_create(THIS_MODULE, "mykey");
    if (IS_ERR(cls)) {
        printk("向上提交目录失败\n");
        ret = -PTR_ERR(cls);
        goto out4;
    }
    printk("向上提交目录成功\n");
    // 向上提交设备节点

    for (i = 0; i < 3; i++) {
        dev = device_create(cls, NULL, MKDEV(major, i), NULL, "mykey%d", i);
        if (IS_ERR(dev)) {
            printk("向上提交节点信息失败\n");
            ret = -PTR_ERR(dev);
            goto out5;
        }
    }
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    // printk("向上提交设备节点信息成功\n");

    // 获取设备信息
    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if (res == NULL) {
        printk("获取资源失败\n");
        return -ENXIO;
    }
    printk("获取资源信息成功 %x\n", res->start);
    irqno = platform_get_irq(pdev, 0);
    if (irqno < 0) {
        printk("获取中断资源失败\n");
        return irqno;
    }
    printk("中断类型资源为%d\n", irqno);
    // 获取gpio信息
    gpiono = gpiod_get_from_of_node(pdev->dev.of_node, "led1", 0, GPIOD_OUT_LOW, NULL);
    if (IS_ERR(gpiono)) {
        printk("解析GPIO信息失败\n");
        return -PTR_ERR(gpiono);
    }

    // 注册中断
    ret = request_irq(irqno, myirq_led_handler, IRQF_TRIGGER_FALLING, "key1", NULL);
    if (ret) {
        printk("注册失败\n");
        return ret;
    }
    return 0;
out5:

    // 销毁提交的设备信息
    device_destroy(cls, MKDEV(major, minor));

    class_destroy(cls);
out4:
    cdev_del(cdev);
out3:
    unregister_chrdev_region(MKDEV(major, minor), 3);
out2:
    kfree(cdev);
out1:
    return ret;
}
// remove 设备和驱动分离时执行
int pdrv_remove(struct platform_device* pdev)
{
    printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);
    // 灭灯
    gpiod_set_value(gpiono, 0);
    // 释放gpio信息
    free_irq(irqno, NULL);
    gpiod_put(gpiono);
    // 销毁设备信息
    int i;
    for (i = 0; i < 3; i++) {
        device_destroy(cls, MKDEV(major, i));
    }
    // 销毁目录
    class_destroy(cls);
    // 注销对象
    cdev_del(cdev);
    // 释放设备号
    unregister_chrdev_region(MKDEV(major, minor), 3);
    // 释放对象空间
    kfree(cdev);
    return 0;
}
// 构建设备树匹配表
struct of_device_id oftable[] = {
    {
        .compatible = "hqyj,myplatform",
    },
    {
        .compatible = "hqyj,myplatform1",
    },
    {},
};
struct platform_driver pdrv = {
    .probe = pdrv_probe,
    .remove = pdrv_remove,
    .driver = {
        .name = "aaaaa",
        .of_match_table = oftable,
    },

};
// 一键注册宏
module_platform_driver(pdrv);
MODULE_LICENSE("GPL");

测试代码：

#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
int main(int argc, char const* argv[])
{
    int fd;

    unsigned int number;
    // 打开LED
    fd = open("/dev/mykey0", O_RDWR);
    if (fd < 0) {
        printf("打开设备文件失败\n");
        exit(-1);
    }

    while (1) {

        read(fd, &number, sizeof(number));
        printf("number=:%d\n", number);
    }
    close(fd);
    return 0;
}