302 lines
7.1 KiB
C
302 lines
7.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* USB Serial Console driver
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*
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* Copyright (C) 2001 - 2002 Greg Kroah-Hartman (greg@kroah.com)
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*
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* Thanks to Randy Dunlap for the original version of this code.
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*
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/tty.h>
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#include <linux/console.h>
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#include <linux/serial.h>
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#include <linux/usb.h>
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#include <linux/usb/serial.h>
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struct usbcons_info {
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int magic;
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int break_flag;
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struct usb_serial_port *port;
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};
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static struct usbcons_info usbcons_info;
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static struct console usbcons;
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/*
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* ------------------------------------------------------------
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* USB Serial console driver
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*
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* Much of the code here is copied from drivers/char/serial.c
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* and implements a phony serial console in the same way that
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* serial.c does so that in case some software queries it,
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* it will get the same results.
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*
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* Things that are different from the way the serial port code
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* does things, is that we call the lower level usb-serial
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* driver code to initialize the device, and we set the initial
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* console speeds based on the command line arguments.
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* ------------------------------------------------------------
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*/
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static const struct tty_operations usb_console_fake_tty_ops = {
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};
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/*
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* The parsing of the command line works exactly like the
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* serial.c code, except that the specifier is "ttyUSB" instead
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* of "ttyS".
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*/
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static int usb_console_setup(struct console *co, char *options)
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{
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struct usbcons_info *info = &usbcons_info;
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int baud = 9600;
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int bits = 8;
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int parity = 'n';
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int doflow = 0;
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int cflag = CREAD | HUPCL | CLOCAL;
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char *s;
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struct usb_serial *serial;
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struct usb_serial_port *port;
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int retval;
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struct tty_struct *tty = NULL;
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struct ktermios dummy;
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if (options) {
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baud = simple_strtoul(options, NULL, 10);
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s = options;
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while (*s >= '0' && *s <= '9')
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s++;
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if (*s)
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parity = *s++;
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if (*s)
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bits = *s++ - '0';
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if (*s)
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doflow = (*s++ == 'r');
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}
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/* Sane default */
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if (baud == 0)
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baud = 9600;
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switch (bits) {
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case 7:
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cflag |= CS7;
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break;
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default:
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case 8:
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cflag |= CS8;
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break;
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}
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switch (parity) {
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case 'o': case 'O':
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cflag |= PARODD;
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break;
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case 'e': case 'E':
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cflag |= PARENB;
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break;
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}
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/*
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* no need to check the index here: if the index is wrong, console
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* code won't call us
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*/
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port = usb_serial_port_get_by_minor(co->index);
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if (port == NULL) {
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/* no device is connected yet, sorry :( */
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pr_err("No USB device connected to ttyUSB%i\n", co->index);
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return -ENODEV;
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}
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serial = port->serial;
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retval = usb_autopm_get_interface(serial->interface);
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if (retval)
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goto error_get_interface;
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tty_port_tty_set(&port->port, NULL);
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info->port = port;
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++port->port.count;
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if (!tty_port_initialized(&port->port)) {
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if (serial->type->set_termios) {
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/*
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* allocate a fake tty so the driver can initialize
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* the termios structure, then later call set_termios to
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* configure according to command line arguments
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*/
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tty = kzalloc(sizeof(*tty), GFP_KERNEL);
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if (!tty) {
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retval = -ENOMEM;
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goto reset_open_count;
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}
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kref_init(&tty->kref);
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tty->driver = usb_serial_tty_driver;
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tty->index = co->index;
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init_ldsem(&tty->ldisc_sem);
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spin_lock_init(&tty->files_lock);
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INIT_LIST_HEAD(&tty->tty_files);
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kref_get(&tty->driver->kref);
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__module_get(tty->driver->owner);
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tty->ops = &usb_console_fake_tty_ops;
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tty_init_termios(tty);
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tty_port_tty_set(&port->port, tty);
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}
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/* only call the device specific open if this
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* is the first time the port is opened */
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retval = serial->type->open(NULL, port);
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if (retval) {
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dev_err(&port->dev, "could not open USB console port\n");
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goto fail;
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}
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if (serial->type->set_termios) {
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tty->termios.c_cflag = cflag;
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tty_termios_encode_baud_rate(&tty->termios, baud, baud);
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memset(&dummy, 0, sizeof(struct ktermios));
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serial->type->set_termios(tty, port, &dummy);
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tty_port_tty_set(&port->port, NULL);
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tty_save_termios(tty);
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tty_kref_put(tty);
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}
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tty_port_set_initialized(&port->port, 1);
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}
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/* Now that any required fake tty operations are completed restore
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* the tty port count */
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--port->port.count;
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/* The console is special in terms of closing the device so
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* indicate this port is now acting as a system console. */
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port->port.console = 1;
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mutex_unlock(&serial->disc_mutex);
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return retval;
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fail:
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tty_port_tty_set(&port->port, NULL);
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tty_kref_put(tty);
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reset_open_count:
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port->port.count = 0;
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info->port = NULL;
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usb_autopm_put_interface(serial->interface);
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error_get_interface:
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usb_serial_put(serial);
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mutex_unlock(&serial->disc_mutex);
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return retval;
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}
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static void usb_console_write(struct console *co,
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const char *buf, unsigned count)
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{
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static struct usbcons_info *info = &usbcons_info;
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struct usb_serial_port *port = info->port;
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struct usb_serial *serial;
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int retval = -ENODEV;
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if (!port || port->serial->dev->state == USB_STATE_NOTATTACHED)
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return;
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serial = port->serial;
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if (count == 0)
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return;
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dev_dbg(&port->dev, "%s - %d byte(s)\n", __func__, count);
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if (!port->port.console) {
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dev_dbg(&port->dev, "%s - port not opened\n", __func__);
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return;
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}
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while (count) {
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unsigned int i;
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unsigned int lf;
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/* search for LF so we can insert CR if necessary */
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for (i = 0, lf = 0 ; i < count ; i++) {
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if (*(buf + i) == 10) {
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lf = 1;
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i++;
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break;
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}
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}
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/* pass on to the driver specific version of this function if
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it is available */
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retval = serial->type->write(NULL, port, buf, i);
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dev_dbg(&port->dev, "%s - write: %d\n", __func__, retval);
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if (lf) {
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/* append CR after LF */
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unsigned char cr = 13;
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retval = serial->type->write(NULL, port, &cr, 1);
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dev_dbg(&port->dev, "%s - write cr: %d\n",
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__func__, retval);
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}
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buf += i;
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count -= i;
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}
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}
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static struct tty_driver *usb_console_device(struct console *co, int *index)
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{
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struct tty_driver **p = (struct tty_driver **)co->data;
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if (!*p)
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return NULL;
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*index = co->index;
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return *p;
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}
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static struct console usbcons = {
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.name = "ttyUSB",
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.write = usb_console_write,
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.device = usb_console_device,
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.setup = usb_console_setup,
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.flags = CON_PRINTBUFFER,
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.index = -1,
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.data = &usb_serial_tty_driver,
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};
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void usb_serial_console_disconnect(struct usb_serial *serial)
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{
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if (serial->port[0] && serial->port[0] == usbcons_info.port) {
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usb_serial_console_exit();
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usb_serial_put(serial);
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}
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}
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void usb_serial_console_init(int minor)
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{
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if (minor == 0) {
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/*
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* Call register_console() if this is the first device plugged
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* in. If we call it earlier, then the callback to
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* console_setup() will fail, as there is not a device seen by
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* the USB subsystem yet.
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*/
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/*
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* Register console.
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* NOTES:
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* console_setup() is called (back) immediately (from
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* register_console). console_write() is called immediately
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* from register_console iff CON_PRINTBUFFER is set in flags.
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*/
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pr_debug("registering the USB serial console.\n");
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register_console(&usbcons);
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}
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}
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void usb_serial_console_exit(void)
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{
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if (usbcons_info.port) {
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unregister_console(&usbcons);
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usbcons_info.port->port.console = 0;
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usbcons_info.port = NULL;
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}
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}
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