drivers/usb/serial/bus.c

// 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,
				   const struct device_driver *drv)
{
	const struct usb_serial_port *port = to_usb_serial_port(dev);
	const struct usb_serial_driver *driver = to_usb_serial_driver(drv);

	/*
	 * drivers are already assigned to ports in serial_probe so it's
	 * a simple check here.
	 */
	if (driver == port->serial->type)
		return 1;

	return 0;
}

static int usb_serial_device_probe(struct device *dev)
{
	struct usb_serial_port *port = to_usb_serial_port(dev);
	struct usb_serial_driver *driver;
	struct device *tty_dev;
	int retval = 0;
	int minor;

	/* 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 void usb_serial_device_remove(struct device *dev)
{
	struct usb_serial_port *port = to_usb_serial_port(dev);
	struct usb_serial_driver *driver;
	int minor;
	int autopm_err;

	/*
	 * 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)
		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);
}

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->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;

	guard(mutex)(&usb_dynids_lock);
	list_for_each_entry_safe(dynid, n, &drv->dynids.list, node) {
		list_del(&dynid->node);
		kfree(dynid);
	}
}

const 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;
	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);
}