1 // SPDX-License-Identifier: GPL-2.0
3  * USB Serial Console driver
5  * Copyright (C) 2001 - 2002 Greg Kroah-Hartman (greg@kroah.com)
7  * Thanks to Randy Dunlap for the original version of this code.
18 #include <linux/serial.h>
19 #include <linux/usb.h>
20 #include <linux/usb/serial.h>
32  * ------------------------------------------------------------
33  * USB Serial console driver
35  * Much of the code here is copied from drivers/char/serial.c
36  * and implements a phony serial console in the same way that
37  * serial.c does so that in case some software queries it,
40  * Things that are different from the way the serial port code
41  * does things, is that we call the lower level usb-serial
42  * driver code to initialize the device, and we set the initial
44  * ------------------------------------------------------------
52  * serial.c code, except that the specifier is "ttyUSB" instead
64 	struct usb_serial *serial;  in usb_console_setup()  local
78 			bits   = *s++ - '0';  in usb_console_setup()
109 	 * no need to check the index here: if the index is wrong, console  in usb_console_setup()
112 	port = usb_serial_port_get_by_minor(co->index);  in usb_console_setup()
115 		pr_err("No USB device connected to ttyUSB%i\n", co->index);  in usb_console_setup()
116 		return -ENODEV;  in usb_console_setup()
118 	serial = port->serial;  in usb_console_setup()
120 	retval = usb_autopm_get_interface(serial->interface);  in usb_console_setup()
124 	tty_port_tty_set(&port->port, NULL);  in usb_console_setup()
126 	info->port = port;  in usb_console_setup()
128 	++port->port.count;  in usb_console_setup()
129 	if (!tty_port_initialized(&port->port)) {  in usb_console_setup()
130 		if (serial->type->set_termios) {  in usb_console_setup()
133 			 * the termios structure, then later call set_termios to  in usb_console_setup()
134 			 * configure according to command line arguments  in usb_console_setup()
138 				retval = -ENOMEM;  in usb_console_setup()
141 			kref_init(&tty->kref);  in usb_console_setup()
142 			tty->driver = usb_serial_tty_driver;  in usb_console_setup()
143 			tty->index = co->index;  in usb_console_setup()
144 			init_ldsem(&tty->ldisc_sem);  in usb_console_setup()
145 			spin_lock_init(&tty->files_lock);  in usb_console_setup()
146 			INIT_LIST_HEAD(&tty->tty_files);  in usb_console_setup()
147 			kref_get(&tty->driver->kref);  in usb_console_setup()
148 			__module_get(tty->driver->owner);  in usb_console_setup()
149 			tty->ops = &usb_console_fake_tty_ops;  in usb_console_setup()
151 			tty_port_tty_set(&port->port, tty);  in usb_console_setup()
156 		retval = serial->type->open(NULL, port);  in usb_console_setup()
158 			dev_err(&port->dev, "could not open USB console port\n");  in usb_console_setup()
162 		if (serial->type->set_termios) {  in usb_console_setup()
163 			tty->termios.c_cflag = cflag;  in usb_console_setup()
164 			tty_termios_encode_baud_rate(&tty->termios, baud, baud);  in usb_console_setup()
166 			serial->type->set_termios(tty, port, &dummy);  in usb_console_setup()
168 			tty_port_tty_set(&port->port, NULL);  in usb_console_setup()
172 		tty_port_set_initialized(&port->port, true);  in usb_console_setup()
176 	--port->port.count;  in usb_console_setup()
179 	port->port.console = 1;  in usb_console_setup()
181 	mutex_unlock(&serial->disc_mutex);  in usb_console_setup()
185 	tty_port_tty_set(&port->port, NULL);  in usb_console_setup()
188 	port->port.count = 0;  in usb_console_setup()
189 	info->port = NULL;  in usb_console_setup()
190 	usb_autopm_put_interface(serial->interface);  in usb_console_setup()
192 	mutex_unlock(&serial->disc_mutex);  in usb_console_setup()
193 	usb_serial_put(serial);  in usb_console_setup()
201 	struct usb_serial_port *port = info->port;  in usb_console_write()
202 	struct usb_serial *serial;  in usb_console_write()  local
203 	int retval = -ENODEV;  in usb_console_write()
205 	if (!port || port->serial->dev->state == USB_STATE_NOTATTACHED)  in usb_console_write()
207 	serial = port->serial;  in usb_console_write()
212 	dev_dbg(&port->dev, "%s - %d byte(s)\n", __func__, count);  in usb_console_write()
214 	if (!port->port.console) {  in usb_console_write()
215 		dev_dbg(&port->dev, "%s - port not opened\n", __func__);  in usb_console_write()
230 		/* pass on to the driver specific version of this function if  in usb_console_write()
232 		retval = serial->type->write(NULL, port, buf, i);  in usb_console_write()
233 		dev_dbg(&port->dev, "%s - write: %d\n", __func__, retval);  in usb_console_write()
237 			retval = serial->type->write(NULL, port, &cr, 1);  in usb_console_write()
238 			dev_dbg(&port->dev, "%s - write cr: %d\n",  in usb_console_write()
242 		count -= i;  in usb_console_write()
248 	struct tty_driver **p = (struct tty_driver **)co->data;  in usb_console_device()
253 	*index = co->index;  in usb_console_device()
263 	.index =	-1,
267 void usb_serial_console_disconnect(struct usb_serial *serial)  in usb_serial_console_disconnect()  argument
269 	if (serial->port[0] && serial->port[0] == usbcons_info.port) {  in usb_serial_console_disconnect()
271 		usb_serial_put(serial);  in usb_serial_console_disconnect()
280 		 * in.  If we call it earlier, then the callback to  in usb_serial_console_init()
282 		 * the USB subsystem yet.  in usb_serial_console_init()
291 		pr_debug("registering the USB serial console.\n");  in usb_serial_console_init()
300 		usbcons_info.port->port.console = 0;  in usb_serial_console_exit()