Linux 内核设备驱动之GPIO驱动之GPIO 框架初始化

static struct bus_type gpio_bus_type = {  .name = "gpio", };  

static int __init gpiolib_dev_init(void) {  int ret;

 /* Register GPIO sysfs bus */  ret  = bus_register(&gpio_bus_type);  if (ret < 0) {   pr_err("gpiolib: could not register GPIO bus type\n");   return ret;  }

 ret = alloc_chrdev_region(&gpio_devt, 0, GPIO_DEV_MAX, "gpiochip");  if (ret < 0) {   pr_err("gpiolib: failed to allocate char dev region\n");   bus_unregister(&gpio_bus_type);  } else {   gpiolib_initialized = true;   gpiochip_setup_devs();  }  return ret; } core_initcall(gpiolib_dev_init);