1 files changed, 304 insertions, 0 deletions
diff --git a/drivers/usb/serial/console.c b/drivers/usb/serial/console.c
new file mode 100644
index 0000000000..c3ea3a46ed
--- /dev/null
+++ b/drivers/usb/serial/console.c
@@ -0,0 +1,304 @@
+// 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, true);
+	}
+	/* 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:
+	mutex_unlock(&serial->disc_mutex);
+	usb_serial_put(serial);
+	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;
+	}
+}
+