drivers/usb/serial/console.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * USB Serial Console driver
  *
  * Copyright (C) 2001 - 2002 Greg Kroah-Hartman (greg@kroah.com)
  *
  * Thanks to Randy Dunlap for the original version of this code.
  *
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/tty.h>
 #include <linux/console.h>
 #include <linux/serial.h>
 #include <linux/usb.h>
 #include <linux/usb/serial.h>

 struct usbcons_info {
 	int			magic;
 	int			break_flag;
 	struct usb_serial_port	*port;
 };

 static struct usbcons_info usbcons_info;
 static struct console usbcons;

 /*
  * ------------------------------------------------------------
  * USB Serial console driver
  *
  * Much of the code here is copied from drivers/char/serial.c
  * and implements a phony serial console in the same way that
  * serial.c does so that in case some software queries it,
  * it will get the same results.
  *
  * Things that are different from the way the serial port code
  * does things, is that we call the lower level usb-serial
  * driver code to initialize the device, and we set the initial
  * console speeds based on the command line arguments.
  * ------------------------------------------------------------
  */

 static const struct tty_operations usb_console_fake_tty_ops = {
 };

 /*
  * The parsing of the command line works exactly like the
  * serial.c code, except that the specifier is "ttyUSB" instead
  * of "ttyS".
  */
 static int usb_console_setup(struct console *co, char *options)
 {
 	struct usbcons_info *info = &usbcons_info;
 	int baud = 9600;
 	int bits = 8;
 	int parity = 'n';
 	int doflow = 0;
 	int cflag = CREAD | HUPCL | CLOCAL;
 	char *s;
 	struct usb_serial *serial;
 	struct usb_serial_port *port;
 	int retval;
 	struct tty_struct *tty = NULL;
 	struct ktermios dummy;

 	if (options) {
 		baud = simple_strtoul(options, NULL, 10);
 		s = options;
 		while (*s >= '0' && *s <= '9')
 			s++;
 		if (*s)
 			parity = *s++;
 		if (*s)
 			bits   = *s++ - '0';
 		if (*s)
 			doflow = (*s++ == 'r');
 	}

 	/* Sane default */
 	if (baud == 0)
 		baud = 9600;

 	switch (bits) {
 	case 7:
 		cflag |= CS7;
 		break;
 	default:
 	case 8:
 		cflag |= CS8;
 		break;
 	}
 	switch (parity) {
 	case 'o': case 'O':
 		cflag |= PARODD;
 		break;
 	case 'e': case 'E':
 		cflag |= PARENB;
 		break;
 	}

 	if (doflow)
 		cflag |= CRTSCTS;

 	/*
 	 * no need to check the index here: if the index is wrong, console
 	 * code won't call us
 	 */
 	port = usb_serial_port_get_by_minor(co->index);
 	if (port == NULL) {
 		/* no device is connected yet, sorry :( */
 		pr_err("No USB device connected to ttyUSB%i\n", co->index);
 		return -ENODEV;
 	}
 	serial = port->serial;

 	retval = usb_autopm_get_interface(serial->interface);
 	if (retval)
 		goto error_get_interface;

 	tty_port_tty_set(&port->port, NULL);

 	info->port = port;

 	++port->port.count;
 	if (!tty_port_initialized(&port->port)) {
 		if (serial->type->set_termios) {
 			/*
 			 * allocate a fake tty so the driver can initialize
 			 * the termios structure, then later call set_termios to
 			 * configure according to command line arguments
 			 */
 			tty = kzalloc(sizeof(*tty), GFP_KERNEL);
 			if (!tty) {
 				retval = -ENOMEM;
 				goto reset_open_count;
 			}
 			kref_init(&tty->kref);
 			tty->driver = usb_serial_tty_driver;
 			tty->index = co->index;
 			init_ldsem(&tty->ldisc_sem);
 			spin_lock_init(&tty->files_lock);
 			INIT_LIST_HEAD(&tty->tty_files);
 			kref_get(&tty->driver->kref);
 			__module_get(tty->driver->owner);
 			tty->ops = &usb_console_fake_tty_ops;
 			tty_init_termios(tty);
 			tty_port_tty_set(&port->port, tty);
 		}

 		/* only call the device specific open if this
 		 * is the first time the port is opened */
 		retval = serial->type->open(NULL, port);
 		if (retval) {
 			dev_err(&port->dev, "could not open USB console port\n");
 			goto fail;
 		}

 		if (serial->type->set_termios) {
 			tty->termios.c_cflag = cflag;
 			tty_termios_encode_baud_rate(&tty->termios, baud, baud);
 			memset(&dummy, 0, sizeof(struct ktermios));
 			serial->type->set_termios(tty, port, &dummy);

 			tty_port_tty_set(&port->port, NULL);
 			tty_save_termios(tty);
 			tty_kref_put(tty);
 		}
 		tty_port_set_initialized(&port->port, 1);
 	}
 	/* Now that any required fake tty operations are completed restore
 	 * the tty port count */
 	--port->port.count;
 	/* The console is special in terms of closing the device so
 	 * indicate this port is now acting as a system console. */
 	port->port.console = 1;

 	mutex_unlock(&serial->disc_mutex);
 	return retval;

  fail:
 	tty_port_tty_set(&port->port, NULL);
 	tty_kref_put(tty);
  reset_open_count:
 	port->port.count = 0;
 	info->port = NULL;
 	usb_autopm_put_interface(serial->interface);
  error_get_interface:
 	usb_serial_put(serial);
 	mutex_unlock(&serial->disc_mutex);
 	return retval;
 }

 static void usb_console_write(struct console *co,
 					const char *buf, unsigned count)
 {
 	static struct usbcons_info *info = &usbcons_info;
 	struct usb_serial_port *port = info->port;
 	struct usb_serial *serial;
 	int retval = -ENODEV;

 	if (!port || port->serial->dev->state == USB_STATE_NOTATTACHED)
 		return;
 	serial = port->serial;

 	if (count == 0)
 		return;

 	dev_dbg(&port->dev, "%s - %d byte(s)\n", __func__, count);

 	if (!port->port.console) {
 		dev_dbg(&port->dev, "%s - port not opened\n", __func__);
 		return;
 	}

 	while (count) {
 		unsigned int i;
 		unsigned int lf;
 		/* search for LF so we can insert CR if necessary */
 		for (i = 0, lf = 0 ; i < count ; i++) {
 			if (*(buf + i) == 10) {
 				lf = 1;
 				i++;
 				break;
 			}
 		}
 		/* pass on to the driver specific version of this function if
 		   it is available */
 		retval = serial->type->write(NULL, port, buf, i);
 		dev_dbg(&port->dev, "%s - write: %d\n", __func__, retval);
 		if (lf) {
 			/* append CR after LF */
 			unsigned char cr = 13;
 			retval = serial->type->write(NULL, port, &cr, 1);
 			dev_dbg(&port->dev, "%s - write cr: %d\n",
 							__func__, retval);
 		}
 		buf += i;
 		count -= i;
 	}
 }

 static struct tty_driver *usb_console_device(struct console *co, int *index)
 {
 	struct tty_driver **p = (struct tty_driver **)co->data;

 	if (!*p)
 		return NULL;

 	*index = co->index;
 	return *p;
 }

 static struct console usbcons = {
 	.name =		"ttyUSB",
 	.write =	usb_console_write,
 	.device =	usb_console_device,
 	.setup =	usb_console_setup,
 	.flags =	CON_PRINTBUFFER,
 	.index =	-1,
 	.data = 	&usb_serial_tty_driver,
 };

 void usb_serial_console_disconnect(struct usb_serial *serial)
 {
 	if (serial->port[0] && serial->port[0] == usbcons_info.port) {
 		usb_serial_console_exit();
 		usb_serial_put(serial);
 	}
 }

 void usb_serial_console_init(int minor)
 {
 	if (minor == 0) {
 		/*
 		 * Call register_console() if this is the first device plugged
 		 * in.  If we call it earlier, then the callback to
 		 * console_setup() will fail, as there is not a device seen by
 		 * the USB subsystem yet.
 		 */
 		/*
 		 * Register console.
 		 * NOTES:
 		 * console_setup() is called (back) immediately (from
 		 * register_console). console_write() is called immediately
 		 * from register_console iff CON_PRINTBUFFER is set in flags.
 		 */
 		pr_debug("registering the USB serial console.\n");
 		register_console(&usbcons);
 	}
 }

 void usb_serial_console_exit(void)
 {
 	if (usbcons_info.port) {
 		unregister_console(&usbcons);
 		usbcons_info.port->port.console = 0;
 		usbcons_info.port = NULL;
 	}
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* USB Serial Console driver
	*
	* Copyright (C) 2001 - 2002 Greg Kroah-Hartman (greg@kroah.com)
	*
	* Thanks to Randy Dunlap for the original version of this code.
	*
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/tty.h>
	#include <linux/console.h>
	#include <linux/serial.h>
	#include <linux/usb.h>
	#include <linux/usb/serial.h>

	struct usbcons_info {
	int magic;
	int break_flag;
	struct usb_serial_port *port;
	};

	static struct usbcons_info usbcons_info;
	static struct console usbcons;

	/*
	* ------------------------------------------------------------
	* USB Serial console driver
	*
	* Much of the code here is copied from drivers/char/serial.c
	* and implements a phony serial console in the same way that
	* serial.c does so that in case some software queries it,
	* it will get the same results.
	*
	* Things that are different from the way the serial port code
	* does things, is that we call the lower level usb-serial
	* driver code to initialize the device, and we set the initial
	* console speeds based on the command line arguments.
	* ------------------------------------------------------------
	*/

	static const struct tty_operations usb_console_fake_tty_ops = {
	};

	/*
	* The parsing of the command line works exactly like the
	* serial.c code, except that the specifier is "ttyUSB" instead
	* of "ttyS".
	*/
	static int usb_console_setup(struct console co, char options)
	{
	struct usbcons_info *info = &usbcons_info;
	int baud = 9600;
	int bits = 8;
	int parity = 'n';
	int doflow = 0;
	int cflag = CREAD \| HUPCL \| CLOCAL;
	char *s;
	struct usb_serial *serial;
	struct usb_serial_port *port;
	int retval;
	struct tty_struct *tty = NULL;
	struct ktermios dummy;

	if (options) {
	baud = simple_strtoul(options, NULL, 10);
	s = options;
	while (s >= '0' && s <= '9')
	s++;
	if (*s)
	parity = *s++;
	if (*s)
	bits = *s++ - '0';
	if (*s)
	doflow = (*s++ == 'r');
	}

	/* Sane default */
	if (baud == 0)
	baud = 9600;

	switch (bits) {
	case 7:
	cflag \|= CS7;
	break;
	default:
	case 8:
	cflag \|= CS8;
	break;
	}
	switch (parity) {
	case 'o': case 'O':
	cflag \|= PARODD;
	break;
	case 'e': case 'E':
	cflag \|= PARENB;
	break;
	}

	if (doflow)
	cflag \|= CRTSCTS;

	/*
	* no need to check the index here: if the index is wrong, console
	* code won't call us
	*/
	port = usb_serial_port_get_by_minor(co->index);
	if (port == NULL) {
	/* no device is connected yet, sorry :( */
	pr_err("No USB device connected to ttyUSB%i\n", co->index);
	return -ENODEV;
	}
	serial = port->serial;

	retval = usb_autopm_get_interface(serial->interface);
	if (retval)
	goto error_get_interface;

	tty_port_tty_set(&port->port, NULL);

	info->port = port;

	++port->port.count;
	if (!tty_port_initialized(&port->port)) {
	if (serial->type->set_termios) {
	/*
	* allocate a fake tty so the driver can initialize
	* the termios structure, then later call set_termios to
	* configure according to command line arguments
	*/
	tty = kzalloc(sizeof(*tty), GFP_KERNEL);
	if (!tty) {
	retval = -ENOMEM;
	goto reset_open_count;
	}
	kref_init(&tty->kref);
	tty->driver = usb_serial_tty_driver;
	tty->index = co->index;
	init_ldsem(&tty->ldisc_sem);
	spin_lock_init(&tty->files_lock);
	INIT_LIST_HEAD(&tty->tty_files);
	kref_get(&tty->driver->kref);
	__module_get(tty->driver->owner);
	tty->ops = &usb_console_fake_tty_ops;
	tty_init_termios(tty);
	tty_port_tty_set(&port->port, tty);
	}

	/* only call the device specific open if this
	* is the first time the port is opened */
	retval = serial->type->open(NULL, port);
	if (retval) {
	dev_err(&port->dev, "could not open USB console port\n");
	goto fail;
	}

	if (serial->type->set_termios) {
	tty->termios.c_cflag = cflag;
	tty_termios_encode_baud_rate(&tty->termios, baud, baud);
	memset(&dummy, 0, sizeof(struct ktermios));
	serial->type->set_termios(tty, port, &dummy);

	tty_port_tty_set(&port->port, NULL);
	tty_save_termios(tty);
	tty_kref_put(tty);
	}
	tty_port_set_initialized(&port->port, 1);
	}
	/* Now that any required fake tty operations are completed restore
	* the tty port count */
	--port->port.count;
	/* The console is special in terms of closing the device so
	* indicate this port is now acting as a system console. */
	port->port.console = 1;

	mutex_unlock(&serial->disc_mutex);
	return retval;

	fail:
	tty_port_tty_set(&port->port, NULL);
	tty_kref_put(tty);
	reset_open_count:
	port->port.count = 0;
	info->port = NULL;
	usb_autopm_put_interface(serial->interface);
	error_get_interface:
	usb_serial_put(serial);
	mutex_unlock(&serial->disc_mutex);
	return retval;
	}

	static void usb_console_write(struct console *co,
	const char *buf, unsigned count)
	{
	static struct usbcons_info *info = &usbcons_info;
	struct usb_serial_port *port = info->port;
	struct usb_serial *serial;
	int retval = -ENODEV;

	if (!port \|\| port->serial->dev->state == USB_STATE_NOTATTACHED)
	return;
	serial = port->serial;

	if (count == 0)
	return;

	dev_dbg(&port->dev, "%s - %d byte(s)\n", __func__, count);

	if (!port->port.console) {
	dev_dbg(&port->dev, "%s - port not opened\n", __func__);
	return;
	}

	while (count) {
	unsigned int i;
	unsigned int lf;
	/* search for LF so we can insert CR if necessary */
	for (i = 0, lf = 0 ; i < count ; i++) {
	if (*(buf + i) == 10) {
	lf = 1;
	i++;
	break;
	}
	}
	/* pass on to the driver specific version of this function if
	it is available */
	retval = serial->type->write(NULL, port, buf, i);
	dev_dbg(&port->dev, "%s - write: %d\n", __func__, retval);
	if (lf) {
	/* append CR after LF */
	unsigned char cr = 13;
	retval = serial->type->write(NULL, port, &cr, 1);
	dev_dbg(&port->dev, "%s - write cr: %d\n",
	__func__, retval);
	}
	buf += i;
	count -= i;
	}
	}

	static struct tty_driver usb_console_device(struct console co, int *index)
	{
	struct tty_driver p = (struct tty_driver )co->data;

	if (!*p)
	return NULL;

	*index = co->index;
	return *p;
	}

	static struct console usbcons = {
	.name = "ttyUSB",
	.write = usb_console_write,
	.device = usb_console_device,
	.setup = usb_console_setup,
	.flags = CON_PRINTBUFFER,
	.index = -1,
	.data = &usb_serial_tty_driver,
	};

	void usb_serial_console_disconnect(struct usb_serial *serial)
	{
	if (serial->port[0] && serial->port[0] == usbcons_info.port) {
	usb_serial_console_exit();
	usb_serial_put(serial);
	}
	}

	void usb_serial_console_init(int minor)
	{
	if (minor == 0) {
	/*
	* Call register_console() if this is the first device plugged
	* in. If we call it earlier, then the callback to
	* console_setup() will fail, as there is not a device seen by
	* the USB subsystem yet.
	*/
	/*
	* Register console.
	* NOTES:
	* console_setup() is called (back) immediately (from
	* register_console). console_write() is called immediately
	* from register_console iff CON_PRINTBUFFER is set in flags.
	*/
	pr_debug("registering the USB serial console.\n");
	register_console(&usbcons);
	}
	}

	void usb_serial_console_exit(void)
	{
	if (usbcons_info.port) {
	unregister_console(&usbcons);
	usbcons_info.port->port.console = 0;
	usbcons_info.port = NULL;
	}
	}