linux/drivers/usb/serial/console.c
Johan Hovold f51ccf4621 USB: serial: console: fix reported terminal settings
The USB-serial console implementation has never reported the actual
terminal settings used. Despite storing the corresponding cflags in its
struct console, these were never honoured on later tty open() where the
tty termios would be left initialised to the driver defaults.

Unlike the serial console implementation, the USB-serial code calls
subdriver open() already at console setup. While calling set_termios()
and write() before open() looks like it could work for some USB-serial
drivers, others definitely do not expect this, so modelling this after
serial core is going to be intrusive, if at all possible.

Instead, use a (renamed) tty helper to save the termios data used at
console setup so that the tty termios reflects the actual terminal
settings after a subsequent tty open().

Note that the calls to tty_init_termios() (tty_driver_install()) and
tty_save_termios() are serialised using the disconnect mutex.

This specifically fixes a regression that was triggered by a recent
change adding software flow control to the pl2303 driver: a getty trying
to disable flow control while leaving the baud rate unchanged would now
also set the baud rate to the driver default (prior to the flow-control
change this had been a noop).

Fixes: 7041d9c3f0 ("USB: serial: pl2303: add support for tx xon/xoff flow control")
Cc: stable <stable@vger.kernel.org>	# 4.18
Cc: Florian Zumbiehl <florz@florz.de>
Reported-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
2018-12-05 11:29:10 +01:00

302 lines
7.1 KiB
C

// 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;
}
/*
* 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;
}
}