text: // SPDX-License-Identifier: GPL-2.0
  /*
   * USB Serial Converter Bus specific functions
   *
   * Copyright (C) 2002 Greg Kroah-Hartman (greg@kroah.com)
   */
  
  #include <linux/kernel.h>
  #include <linux/errno.h>
  #include <linux/tty.h>
  #include <linux/slab.h>
  #include <linux/module.h>
  #include <linux/usb.h>
  #include <linux/usb/serial.h>
  
  static int usb_serial_device_match(struct device *dev,
  						struct device_driver *drv)
  {
  	struct usb_serial_driver *driver;
  	const struct usb_serial_port *port;
  
  	/*
  	 * drivers are already assigned to ports in serial_probe so it's
  	 * a simple check here.
  	 */
  	port = to_usb_serial_port(dev);
  	if (!port)
  		return 0;
  
  	driver = to_usb_serial_driver(drv);
  
  	if (driver == port->serial->type)
  		return 1;
  
  	return 0;
  }
  
  static int usb_serial_device_probe(struct device *dev)
  {
  	struct usb_serial_driver *driver;
  	struct usb_serial_port *port;
  	struct device *tty_dev;
  	int retval = 0;
  	int minor;
  
  	port = to_usb_serial_port(dev);
  	if (!port)
  		return -ENODEV;
  
  	/* make sure suspend/resume doesn't race against port_probe */
  	retval = usb_autopm_get_interface(port->serial->interface);
  	if (retval)
  		return retval;
  
  	driver = port->serial->type;
  	if (driver->port_probe) {
  		retval = driver->port_probe(port);
  		if (retval)
  			goto err_autopm_put;
  	}
  
  	minor = port->minor;
  	tty_dev = tty_port_register_device(&port->port, usb_serial_tty_driver,
  					   minor, dev);
  	if (IS_ERR(tty_dev)) {
  		retval = PTR_ERR(tty_dev);
  		goto err_port_remove;
  	}
  
  	usb_autopm_put_interface(port->serial->interface);
  
  	dev_info(&port->serial->dev->dev,
  		 "%s converter now attached to ttyUSB%d\n",
  		 driver->description, minor);
  
  	return 0;
  
  err_port_remove:
  	if (driver->port_remove)
  		driver->port_remove(port);
  err_autopm_put:
  	usb_autopm_put_interface(port->serial->interface);
  
  	return retval;
  }
  
  static int usb_serial_device_remove(struct device *dev)
  {
  	struct usb_serial_driver *driver;
  	struct usb_serial_port *port;
  	int retval = 0;
  	int minor;
  	int autopm_err;
  
  	port = to_usb_serial_port(dev);
  	if (!port)
  		return -ENODEV;
  
  	/*
  	 * Make sure suspend/resume doesn't race against port_remove.
  	 *
  	 * Note that no further runtime PM callbacks will be made if
  	 * autopm_get fails.
  	 */
  	autopm_err = usb_autopm_get_interface(port->serial->interface);
  
  	minor = port->minor;
  	tty_unregister_device(usb_serial_tty_driver, minor);
  
  	driver = port->serial->type;
  	if (driver->port_remove)
  		retval = driver->port_remove(port);
  
  	dev_info(dev, "%s converter now disconnected from ttyUSB%d\n",
  		 driver->description, minor);
  
  	if (!autopm_err)
  		usb_autopm_put_interface(port->serial->interface);
  
  	return retval;
  }
  
  static ssize_t new_id_store(struct device_driver *driver,
  			    const char *buf, size_t count)
  {
  	struct usb_serial_driver *usb_drv = to_usb_serial_driver(driver);
  	ssize_t retval = usb_store_new_id(&usb_drv->dynids, usb_drv->id_table,
  					 driver, buf, count);
  
  	if (retval >= 0 && usb_drv->usb_driver != NULL)
  		retval = usb_store_new_id(&usb_drv->usb_driver->dynids,
  					  usb_drv->usb_driver->id_table,
  					  &usb_drv->usb_driver->drvwrap.driver,
  					  buf, count);
  	return retval;
  }
  
  static ssize_t new_id_show(struct device_driver *driver, char *buf)
  {
  	struct usb_serial_driver *usb_drv = to_usb_serial_driver(driver);
  
  	return usb_show_dynids(&usb_drv->dynids, buf);
  }
  static DRIVER_ATTR_RW(new_id);
  
  static struct attribute *usb_serial_drv_attrs[] = {
  	&driver_attr_new_id.attr,
  	NULL,
  };
  ATTRIBUTE_GROUPS(usb_serial_drv);
  
  static void free_dynids(struct usb_serial_driver *drv)
  {
  	struct usb_dynid *dynid, *n;
  
  	spin_lock(&drv->dynids.lock);
  	list_for_each_entry_safe(dynid, n, &drv->dynids.list, node) {
  		list_del(&dynid->node);
  		kfree(dynid);
  	}
  	spin_unlock(&drv->dynids.lock);
  }
  
  struct bus_type usb_serial_bus_type = {
  	.name =		"usb-serial",
  	.match =	usb_serial_device_match,
  	.probe =	usb_serial_device_probe,
  	.remove =	usb_serial_device_remove,
  	.drv_groups = 	usb_serial_drv_groups,
  };
  
  int usb_serial_bus_register(struct usb_serial_driver *driver)
  {
  	int retval;
  
  	driver->driver.bus = &usb_serial_bus_type;
  	spin_lock_init(&driver->dynids.lock);
  	INIT_LIST_HEAD(&driver->dynids.list);
  
  	retval = driver_register(&driver->driver);
  
  	return retval;
  }
  
  void usb_serial_bus_deregister(struct usb_serial_driver *driver)
  {
  	free_dynids(driver);
  	driver_unregister(&driver->driver);
  }
  
  