Linux 内核设备驱动之GPIO驱动之GPIO GPIO字符设备初始化

static void gpiochip_setup_devs(void) {  struct gpio_device *gdev;  int err;

 list_for_each_entry(gdev, &gpio_devices, list) {   err = gpiochip_setup_dev(gdev);   if (err)    pr_err("%s: Failed to initialize gpio device (%d)\n",           dev_name(&gdev->dev), err);  } }

  static const struct file_operations gpio_fileops = {  .release = gpio_chrdev_release,  .open = gpio_chrdev_open,  .owner = THIS_MODULE,  .llseek = noop_llseek,  .unlocked_ioctl = gpio_ioctl, #ifdef CONFIG_COMPAT  .compat_ioctl = gpio_ioctl_compat, #endif };  

static int gpiochip_setup_dev(struct gpio_device *gdev) {  int status;

 cdev_init(&gdev->chrdev, &gpio_fileops);  gdev->chrdev.owner = THIS_MODULE;  gdev->chrdev.kobj.parent = &gdev->dev.kobj;  gdev->dev.devt = MKDEV(MAJOR(gpio_devt), gdev->id);  status = cdev_add(&gdev->chrdev, gdev->dev.devt, 1);  if (status < 0)   chip_warn(gdev->chip, "failed to add char device %d:%d\n",      MAJOR(gpio_devt), gdev->id);  else   chip_dbg(gdev->chip, "added GPIO chardev (%d:%d)\n",     MAJOR(gpio_devt), gdev->id);  status = device_add(&gdev->dev);  if (status)   goto err_remove_chardev;

 status = gpiochip_sysfs_register(gdev);  if (status)   goto err_remove_device;

 /* From this point, the .release() function cleans up gpio_device */  gdev->dev.release = gpiodevice_release;  pr_debug("%s: registered GPIOs %d to %d on device: %s (%s)\n",    __func__, gdev->base, gdev->base + gdev->ngpio - 1,    dev_name(&gdev->dev), gdev->chip->label ? : "generic");

 return 0;

err_remove_device:  device_del(&gdev->dev); err_remove_chardev:  cdev_del(&gdev->chrdev);  return status; }