linux platform bus一个driver多个device的问题

sharemon 2018-07-18 02:33:56

刚接触platform bus，学习的时候遇到一个问题。我现在想用1个led的driver驱动4个led的device。我的想法是先注册driver，然后注册device，每匹配上一个device就新建一个/dev/ledx(x 从0到3)，然后在应用程序里打开不同的/dev/ledx来控制不同的led。

但是我在实验的时候发现，不管我用应用程序打开哪个/dev/ledx，控制的永远是我最后一个注册的led device。led driver的代码在下面（只保留了platform相关内容）。我觉得是不是因为我的led的设备描述符只有一个（led_dev），所以最后注册的led device会覆盖以前注册的设备的信息，导致这种现象？那不知道一般对于这种问题的做法是什么？谢谢

struct led_dev_t

{

    const char * dev_name;

    unsigned long major;

    struct class * cls;

    struct device * dev;

    void * reg_virt_base;

    int led_gpio_bit;

};



static struct led_dev_t * led_dev;





int led_dev_release(struct inode *inode, struct file *filp)

{

    return 0;

}





int pdrv_probe(struct platform_device * pdev)

{

    struct resource * rsc;



    int ret;

    unsigned int gpio_base_addr;

    unsigned int gpio_base_addr_size;

    unsigned int gpio_conf_val;

    

    // Apply resources

    printk("------------%s------------\n", __FUNCTION__);

    

    // malloc memory for led description

    led_dev = (struct led_dev_t *)kzalloc(sizeof(struct led_dev_t), GFP_KERNEL);

    

    // get resource from device

    rsc = platform_get_resource(pdev, IORESOURCE_MEM, 0);

    gpio_base_addr = (unsigned int)rsc->start;

    gpio_base_addr_size = (unsigned int)resource_size(rsc);

    led_dev->led_gpio_bit = *((int *)pdev->dev.platform_data); 

    led_dev->dev_name = pdev->dev.kobj.name;



    // register device number

    led_dev->major = register_chrdev(0,led_dev->dev_name, &dev_fops);



    led_dev->cls = led_cls;

    // create device node

    led_dev->dev = device_create(led_dev->cls, NULL, MKDEV(led_dev->major, 1), NULL, led_dev->dev_name);



    // io remap

    led_dev->reg_virt_base = ioremap(gpio_base_addr, gpio_base_addr_size)；



    // config gpio as output

    gpio_conf_val = readl(led_dev->reg_virt_base);

    gpio_conf_val &= ~(0xf<<(led_dev->led_gpio_bit*4));

    gpio_conf_val |= (0x1<<(led_dev->led_gpio_bit*4));

    writel(gpio_conf_val, led_dev->reg_virt_base);



    return 0;

}



int pdrv_remove(struct platform_device * pdev)

{

    printk("-----------------------%s---------------------\n", __FUNCTION__);

    device_destroy(led_dev->cls, MKDEV(led_dev->major, 1));

    printk("devie destroyed!\n");



    unregister_chrdev(led_dev->major, led_dev->dev_name);

    printk("char dev unregistered!\n");

    

    kfree(led_dev);

    return 0;

}



struct platform_device_id led_id_table[] = {

    {"4412-led", 1},

};



struct platform_driver pdrv = {

    .probe = pdrv_probe,

    .remove = pdrv_remove,

    .driver = {

        .name = "4412_led_driver",

    },

    .id_table = led_id_table,

};



static int __init led_drv_init(void)

{

    int ret;



    printk("-----------------------%s---------------------\n", __FUNCTION__);



    // construct /sys/bus/mybus/devices/...

    ret = platform_driver_register(&pdrv);

    if(ret != 0) {

        printk("device register error!\n");

        return ret;

    }



    // create device class

    led_cls = class_create(THIS_MODULE, "led");

    if (IS_ERR(led_dev->cls))

    {

        printk(KERN_ERR "create class error\n");

        kfree(led_dev);

        return PTR_ERR(led_dev->cls);

    }



    return 0;

}



static void __exit led_drv_exit(void)

{

    printk("-----------------------%s---------------------\n", __FUNCTION__);

    class_destroy(led_dev->cls);

    platform_driver_unregister(&pdrv);

}





module_init(led_drv_init);

module_exit(led_drv_exit);

MODULE_LICENSE("GPL");