关于SPI驱动注册中，设备节点的问题，请高手解答

[gomogomono]

static int __init spidev_init(void)
{
	int status;

	/* Claim our 256 reserved device numbers.  Then register a class
	 * that will key udev/mdev to add/remove /dev nodes.  Last, register
	 * the driver which manages those device numbers.
	 */
	BUILD_BUG_ON(N_SPI_MINORS > 256);
	status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
	if (status < 0)
		return status;

	spidev_class = class_create(THIS_MODULE, "spidev");
	if (IS_ERR(spidev_class)) {
		unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name);
		return PTR_ERR(spidev_class);
	}

	status = spi_register_driver(&spidev_spi);
	if (status < 0) {
		class_destroy(spidev_class);
		unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name);
	}
	return status;
}

上面是spidev.c中的代码，我想问的是这段代码中，有两个注册函数 register_chrdev和spi_register_driver
，那是不是会创建两个设备节点啊

[gomogomono]

为什么没人呢

[gomogomono]

引用 2 楼 godwww 的回复:

给你参考下我的代码，我的会创建一个节点/dev/gpio47 static int cxdish_gpiocdev_init(struct cxdish_gpio_cdev *gpio_cdev) { int err; struct device *dev; err = alloc_chrdev_region(&gpio_cdev->dev, 0, 1, "cxdish_gpio_cdev"); if(err){ printk("cxdish_gpiocdev_init:unable get a dynamic major\n"); goto fail_add; } cdev_init(&gpio_cdev->cdev, &cxdish_gpio_fops); gpio_cdev->cdev.owner = THIS_MODULE; err = cdev_add(&gpio_cdev->cdev, gpio_cdev->dev, 1); if(err) { printk("gpiocdev_init:unable to register char device\n"); goto fail_add; } gpio_cdev->class = class_create(THIS_MODULE, "cxdish_gpio_cdev"); if(IS_ERR(gpio_cdev->class)){ printk("cxdish_gpiocdev_init class !\n"); err = PTR_ERR(gpio_cdev->class); goto err_class; } dev = device_create(gpio_cdev->class, NULL, gpio_cdev->dev, NULL, "gpio%d", 47); // last param is i2c_num ,choose 0 if(IS_ERR(dev)){ printk("Failed to create device !\n"); err = PTR_ERR(dev); goto err_device; }

就是说最终的设备节点是通过device_create这个函数来决定的，是吗？

[godwww]

给你参考下我的代码，我的会创建一个节点/dev/gpio47 static int cxdish_gpiocdev_init(struct cxdish_gpio_cdev *gpio_cdev) { int err; struct device *dev; err = alloc_chrdev_region(&gpio_cdev->dev, 0, 1, "cxdish_gpio_cdev"); if(err){ printk("cxdish_gpiocdev_init:unable get a dynamic major\n"); goto fail_add; } cdev_init(&gpio_cdev->cdev, &cxdish_gpio_fops); gpio_cdev->cdev.owner = THIS_MODULE; err = cdev_add(&gpio_cdev->cdev, gpio_cdev->dev, 1); if(err) { printk("gpiocdev_init:unable to register char device\n"); goto fail_add; } gpio_cdev->class = class_create(THIS_MODULE, "cxdish_gpio_cdev"); if(IS_ERR(gpio_cdev->class)){ printk("cxdish_gpiocdev_init class !\n"); err = PTR_ERR(gpio_cdev->class); goto err_class; } dev = device_create(gpio_cdev->class, NULL, gpio_cdev->dev, NULL, "gpio%d", 47); // last param is i2c_num ,choose 0 if(IS_ERR(dev)){ printk("Failed to create device !\n"); err = PTR_ERR(dev); goto err_device; }

[tgcoffee]

真心不错学习了！

[Eliot_shao]

register_chrdev和spi_register_driver分别在/dev和/sys下面创建文件节点。