pcDuino day4

hello_module2.c

static int __init hello_init(void)
{
    printk(DEVICE_NAME" Hello world in kernel module\n");

    major = register_chrdev(0, DEVICE_NAME, &hello_fops);   //12位主設備號 20位次設備號
    if(major < 0){
        printk(DEVICE_NAME" register %s fial\n", DEVICE_NAME);
        return major;
    }
    dev_class = class_create(THIS_MODULE, DEVICE_NAME);
    if(dev_class == NULL)
        printk("device node create fail\n");
    else
    {
        dev_t dev = MKDEV(major, 0);
        device_create(dev_class, NULL, MKDEV(major, 0), NULL, "hello"); //自動創建設備結點 /proc/device/
    }
    printk(DEVICE_NAME" got major number: %d\n", major);
    return 0;
}

hello_module_cdev.c

static int __init hello_init(void)
{
    int result;
    printk(DEVICE_NAME" Hello world in kernel module\n");

    result = alloc_chrdev_region(&g_devno, 0, DEVICE_COUNT, DEVICE_NAME); //次設備 從0開始 數量DEVICE_COUNT個
    if(result < 0)
    {
        printk("alloc_chrdev_region fail\n");
        return result;
    }
    major = MAJOR(g_devno);
    minor = MINOR(g_devno);

    cdev_init(&g_cdev, &hello_fops);
    g_cdev.ops = &hello_fops;
    g_cdev.owner = THIS_MODULE;

    result = cdev_add(&g_cdev, g_devno, DEVICE_COUNT);  //把設備號與字符設備關聯
    if(result)
    {
        printk("add cdev error\n");
        unregister_chrdev_region(g_devno, DEVICE_COUNT); //添加失敗 回收設備號
        return result;
    }

    dev_class = class_create(THIS_MODULE, DEVICE_NAME);
    if(dev_class == NULL)
    {
        printk("device node create fail\n");
    }
    else
    {
    //  dev_t dev = MKDEV(major, 0);
        int i;
        for(i = 0; i < DEVICE_COUNT; i++)
            device_create(dev_class, NULL, g_devno + i, NULL, "%s%d", DEVICE_NAME, i); //自動創建設備結點 /proc/device/
    }
    printk(DEVICE_NAME" got major number: %d\n", major);
    return 0;
}