patch-2.4.6 linux/drivers/usb/serial/pl2303.c

• Lines: 845
• Date: Wed Jun 27 13:59:32 2001
• Orig file: v2.4.5/linux/drivers/usb/serial/pl2303.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.5/linux/drivers/usb/serial/pl2303.c linux/drivers/usb/serial/pl2303.c
@@ -0,0 +1,844 @@
+/*
+ * Prolific PL2303 USB to serial adaptor driver
+ *
+ * Copyright (C) 2001 Greg Kroah-Hartman (greg@kroah.com)
+ *
+ * Original driver for 2.2.x by anonymous
+ *
+ *	This program is free software; you can redistribute it and/or modify
+ *	it under the terms of the GNU General Public License as published by
+ *	the Free Software Foundation; either version 2 of the License, or
+ *	(at your option) any later version.
+ *
+ * See Documentation/usb/usb-serial.txt for more information on using this driver
+ *
+ * 2001_Jun_06 gkh
+ *	finished porting to 2.4 format.
+ * 
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/signal.h>
+#include <linux/errno.h>
+#include <linux/poll.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/fcntl.h>
+#include <linux/tty.h>
+#include <linux/tty_driver.h>
+#include <linux/tty_flip.h>
+#include <linux/serial.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/usb.h>
+
+#ifdef CONFIG_USB_SERIAL_DEBUG
+	static int debug = 1;
+#else
+	static int debug;
+#endif
+
+#include "usb-serial.h"
+#include "pl2303.h"
+
+/*
+ * Version Information
+ */
+#define DRIVER_VERSION "v0.5"
+#define DRIVER_DESC "Prolific PL2303 USB to serial adaptor driver"
+
+
+#ifndef MIN
+#define MIN(a,b)        ((a) < (b) ? (a) : (b))
+#endif
+
+
+#define	PL2303_LOCK(port,flags)					\
+		do {						\
+		spin_lock_irqsave(&((struct pl2303_private *)(port->private))->lock, flags);	\
+		} while (0)
+
+#define	PL2303_UNLOCK(port,flags)				\
+		do {						\
+		spin_unlock_irqrestore(&((struct pl2303_private *)(port->private))->lock, flags);	\
+		} while (0)
+
+
+
+static __devinitdata struct usb_device_id id_table [] = {
+	{ USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID) },
+	{ USB_DEVICE(ATEN_VENDOR_ID, ATEN_PRODUCT_ID) },
+	{ }					/* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE (usb, id_table);
+
+struct pl2303_private {
+	spinlock_t	lock;
+	unsigned char	*xmit_buf;
+	int		xmit_head;
+	int		xmit_tail;
+	int		xmit_cnt;
+};
+
+/* function prototypes for a PL2303 serial converter */
+static int pl2303_startup (struct usb_serial *serial);
+static int pl2303_open (struct usb_serial_port *port, struct file *filp);
+static void pl2303_close (struct usb_serial_port *port, struct file *filp);
+static void pl2303_set_termios (struct usb_serial_port *port,
+				struct termios *old);
+static int pl2303_ioctl (struct usb_serial_port *port, struct file *file,
+			 unsigned int cmd, unsigned long arg);
+static void pl2303_throttle (struct usb_serial_port *port);
+static void pl2303_unthrottle (struct usb_serial_port *port);
+static void pl2303_read_int_callback (struct urb *urb);
+static void pl2303_read_bulk_callback (struct urb *urb);
+static void pl2303_write_bulk_callback (struct urb *urb);
+static int pl2303_write (struct usb_serial_port *port, int from_user,
+			 const unsigned char *buf, int count);
+static int pl2303_write_room(struct usb_serial_port *port);
+static int pl2303_chars_in_buffer(struct usb_serial_port *port);
+static void pl2303_break_ctl(struct usb_serial_port *port,int break_state);
+static void start_xmit (struct usb_serial_port *port);
+
+
+/* All of the device info needed for the PL2303 SIO serial converter */
+static struct usb_serial_device_type pl2303_device = {
+	name:			"PL-2303",
+	id_table:		id_table,
+	needs_interrupt_in:	DONT_CARE,		/* this device must have an interrupt in endpoint */
+	needs_bulk_in:		MUST_HAVE,		/* this device must have a bulk in endpoint */
+	needs_bulk_out:		MUST_HAVE,		/* this device must have a bulk out endpoint */
+	num_interrupt_in:	NUM_DONT_CARE,
+	num_bulk_in:		1,
+	num_bulk_out:		1,
+	num_ports:		1,
+	open:			pl2303_open,
+	close:			pl2303_close,
+	throttle:		pl2303_throttle,
+	unthrottle:		pl2303_unthrottle,
+	write:			pl2303_write,
+	ioctl:			pl2303_ioctl,
+	write_room:		pl2303_write_room,
+	chars_in_buffer:	pl2303_chars_in_buffer,
+	break_ctl:		pl2303_break_ctl,
+	set_termios:		pl2303_set_termios,
+	read_bulk_callback:	pl2303_read_bulk_callback,
+	read_int_callback:	pl2303_read_int_callback,
+	write_bulk_callback:	pl2303_write_bulk_callback,
+	startup:		pl2303_startup,
+};
+
+
+#define WDR_TIMEOUT (HZ * 5 )   /* default urb timeout */
+
+static unsigned char *tmp_buf;
+static DECLARE_MUTEX (tmp_buf_sem);
+
+
+
+static int
+pl2303_write (struct usb_serial_port *port, int from_user,
+	      const unsigned char *buf, int count)
+{				/* pl2303_write */
+	struct pl2303_private *info = (struct pl2303_private *)port->private;
+	unsigned long flags;
+	int c,ret=0;
+	struct tty_struct *tty=port->tty;
+
+	dbg ("pl2303_write port %d, %d bytes", port->number, count);
+
+	if (!info) {
+		return -ENODEV;
+	}
+
+	if (!tty || !info->xmit_buf || !tmp_buf) {
+		return 0;
+	}
+
+
+	PL2303_LOCK(port,flags);
+
+
+	if (from_user) {
+		down(&tmp_buf_sem);
+		while (1) {
+			c = MIN(count, MIN(SERIAL_XMIT_SIZE - info->xmit_cnt - 1,
+					   SERIAL_XMIT_SIZE - info->xmit_head));
+			if (c <= 0)
+				break;
+
+			c -= copy_from_user(tmp_buf, buf, c);
+			if (!c) {
+				if (!ret) {
+					ret = -EFAULT;
+				}
+				break;
+			}
+			c = MIN(c, MIN(SERIAL_XMIT_SIZE - info->xmit_cnt - 1,
+				       SERIAL_XMIT_SIZE - info->xmit_head));
+			memcpy(info->xmit_buf + info->xmit_head, tmp_buf, c);
+			info->xmit_head = ((info->xmit_head + c) & (SERIAL_XMIT_SIZE-1));
+			info->xmit_cnt += c;
+			buf += c;
+			count -= c;
+			ret += c;
+		}
+		up(&tmp_buf_sem);
+	} else {
+		while (1) {
+			c = MIN(count, MIN(SERIAL_XMIT_SIZE - info->xmit_cnt - 1, 
+					   SERIAL_XMIT_SIZE - info->xmit_head));
+			if (c <= 0) {
+				break;
+			}
+			memcpy(info->xmit_buf + info->xmit_head, buf, c);
+			info->xmit_head = (info->xmit_head + c) & (SERIAL_XMIT_SIZE-1);
+			info->xmit_cnt += c;
+			buf += c;
+			count -= c;
+			ret += c;
+		}
+	}
+	PL2303_UNLOCK(port, flags);
+
+	if (info->xmit_cnt && !tty->stopped && !tty->hw_stopped) {
+		start_xmit(port);
+	}
+	return ret;
+}
+
+static int pl2303_write_room(struct usb_serial_port *port)
+{
+	struct pl2303_private *info = (struct pl2303_private *)port->private;
+	int     ret;
+
+	if (!info)
+		return 0;
+
+	ret = SERIAL_XMIT_SIZE - info->xmit_cnt - 1;
+	if (ret < 0)
+		ret = 0;
+	return ret;
+}
+
+static int pl2303_chars_in_buffer(struct usb_serial_port *port)
+{
+	struct pl2303_private *info = (struct pl2303_private *)port->private;
+
+	if (!info)
+		return 0;
+
+	return info->xmit_cnt;
+}
+
+static void pl2303_throttle(struct usb_serial_port *port)
+{
+#if 0
+	//struct usb_serial *serial = port->serial;
+	struct tty_struct *tty=port->tty;
+	unsigned long flags;
+
+
+	char    buf[64];
+
+	dbg("throttle %s: %d....", tty_name(tty, buf),
+	    tty->ldisc.chars_in_buffer(tty));
+
+//FIXME FIXME FIXME	
+	if (I_IXOFF(tty))
+		rs_send_xchar(tty, STOP_CHAR(tty));
+
+	PL2303_LOCK(port,flags);
+	//Should remove read request if one is present
+	PL2303_UNLOCK(port,flags);
+#endif
+}
+
+static void pl2303_unthrottle(struct usb_serial_port *port)
+{
+#if 0
+	//struct usb_serial *serial = port->serial;
+	struct tty_struct *tty=port->tty;
+	unsigned long flags;
+
+
+	char    buf[64];
+
+	dbg("unthrottle %s: %d....", tty_name(tty, buf),
+	    tty->ldisc.chars_in_buffer(tty));
+
+	//FIXME FIXME FIXME FIXME FIXME
+	if (I_IXOFF(tty)) {
+		if (info->x_char)
+			info->x_char = 0;
+		else
+			rs_send_xchar(tty, START_CHAR(tty));
+	}
+
+	PL2303_LOCK(port,flags);
+	//Should add read request if one is not present
+	PL2303_UNLOCK(fport,flags);
+#endif
+}
+
+
+static void
+pl2303_set_termios (struct usb_serial_port *port, struct termios *old_termios)
+{				/* pl2303_set_termios */
+	struct usb_serial *serial = port->serial;
+	unsigned int cflag = port->tty->termios->c_cflag;
+	unsigned char buf[7] = { 0, 0, 0, 0, 0, 0, 0};
+	int baud;
+	int i;
+
+
+	dbg ("pl2303_set_termios port %d", port->number);
+
+
+	i = usb_control_msg (serial->dev, usb_rcvctrlpipe (serial->dev, 0),
+			     0x21, 0xa1, 0, 0, buf, 7, 100);
+
+	dbg ("0xa1:0x21:0:0  %d - %x %x %x %x %x %x %x", i,
+	     buf[0], buf[1], buf[2], buf[3], buf[4], buf[5], buf[6]);
+
+
+	i = usb_control_msg (serial->dev, usb_sndctrlpipe (serial->dev, 0),
+			     1, 0x40, 0, 1, NULL, 0, 100);
+
+	dbg ("0x40:1:0:1  %d", i);
+
+
+
+	if (cflag & CSIZE) {
+		switch (cflag & CSIZE) {
+			case CS6:
+				buf[6] = 6;
+				dbg ("Setting CS6");
+				break;
+			case CS7:
+				buf[6] = 7;
+				dbg ("Setting CS7");
+				break;
+			case CS8:
+				buf[6] = 8;
+				dbg ("Setting CS8");
+				break;
+			default:
+				err ("CSIZE was set but not CS6-CS8");
+		}
+	}
+
+	baud = 0;
+	switch (cflag & CBAUD) {
+		case B0:
+			err ("Can't do B0 yet");  //FIXME
+			break;
+		case B300:
+			baud = 300;
+			break;
+		case B600:
+			baud = 600;
+			break;
+		case B1200:
+			baud = 1200;
+			break;
+		case B2400:
+			baud = 2400;
+			break;
+		case B4800:
+			baud = 4800;
+			break;
+		case B9600:
+			baud = 9600;
+			break;
+		case B19200:
+			baud = 19200;
+			break;
+		case B38400:
+			baud = 38400;
+			break;
+		case B57600:
+			baud = 57600;
+			break;
+		case B115200:
+			baud = 115200;
+			break;
+		default:
+			dbg ("pl2303 driver does not support the baudrate requested (fix it)");
+			break;
+	}
+
+	if (baud) {
+		buf[0] = baud & 0xff;
+		buf[1] = (baud >> 8) & 0xff;
+		buf[2] = (baud >> 16) & 0xff;
+		buf[3] = (baud >> 24) & 0xff;
+	}
+
+
+	/* For reference buf[4]=1 is 1.5 stop bits */
+
+	if (cflag & CSTOPB) {
+		buf[4] = 2;
+	}
+
+
+	if (cflag & PARENB) {
+		/* For reference buf[5]=3 is mark parity */
+		/* For reference buf[5]=4 is space parity */
+		if (cflag & PARODD) {
+			buf[5] = 1;
+		} else {
+			buf[5] = 2;
+		}
+	}
+
+	i = usb_control_msg (serial->dev, usb_sndctrlpipe (serial->dev, 0),
+			     0x20, 0x21, 0, 0, buf, 7, 100);
+
+	dbg ("0x21:0x20:0:0  %d", i);
+
+	i = usb_control_msg (serial->dev, usb_sndctrlpipe (serial->dev, 0),
+			     0x22, 0x21, 1, 0, NULL, 0, 100);
+
+	dbg ("0x21:0x22:1:0  %d", i);
+
+	i = usb_control_msg (serial->dev, usb_sndctrlpipe (serial->dev, 0),
+			     0x22, 0x21, 3, 0, NULL, 0, 100);
+
+	dbg ("0x21:0x22:3:0  %d", i);
+
+	buf[0] = buf[1] = buf[2] = buf[3] = buf[4] = buf[5] = buf[6] = 0;
+
+	i = usb_control_msg (serial->dev, usb_rcvctrlpipe (serial->dev, 0),
+			     0x21, 0xa1, 0, 0, buf, 7, 100);
+
+	dbg ("0xa1:0x21:0:0  %d - %x %x %x %x %x %x %x", i,
+	     buf[0], buf[1], buf[2], buf[3], buf[4], buf[5], buf[6]);
+
+	if (cflag & CRTSCTS) {
+
+		i = usb_control_msg (serial->dev, usb_sndctrlpipe (serial->dev, 0),
+				     0x01, 0x40, 0x0, 0x41, NULL, 0, 100);
+
+		dbg ("0x40:0x1:0x0:0x41  %d", i);
+
+	}
+
+
+	return;
+}       
+
+
+static int
+pl2303_open (struct usb_serial_port *port, struct file *filp)
+{				/* pl2303_open */
+	struct termios tmp_termios;
+	struct usb_serial *serial = port->serial;
+	unsigned char buf[10];
+	int i;
+
+	dbg ("pl2303_open port %d", port->number);
+
+	port->active++;
+
+#define FISH(a,b,c,d) \
+	i=usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev,0), \
+		    b, a,c  , d, buf, 1, 100); \
+	dbg("0x%x:0x%x:0x%x:0x%x  %d - %x",a,b,c,d,i,buf[0]);
+
+#define SOUP(a,b,c,d) \
+	i=usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev,0), \
+		    b, a,c  , d, NULL, 0, 100); \
+	dbg("0x%x:0x%x:0x%x:0x%x  %d",a,b,c,d,i);
+
+
+	FISH (0xc0, 1, 0x8484, 0);
+	SOUP (0x40, 1, 0x0404, 0);
+	FISH (0xc0, 1, 0x8484, 0);
+	FISH (0xc0, 1, 0x8383, 0);
+	FISH (0xc0, 1, 0x8484, 0);
+	SOUP (0x40, 1, 0x0404, 1);
+	FISH (0xc0, 1, 0x8484, 0);
+	FISH (0xc0, 1, 0x8383, 0);
+	SOUP (0x40, 1, 0, 1);
+	SOUP (0x40, 1, 1, 0xc0);
+	SOUP (0x40, 1, 2, 4);
+
+	/* Setup termios */
+
+	if (port->active == 1) {
+		*(port->tty->termios) = tty_std_termios;
+		port->tty->termios->c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
+	}
+
+
+	pl2303_set_termios (port, &tmp_termios);
+
+	//FIXME: need to assert RTS and DTR if CRTSCTS off
+
+
+	if (port->active == 1) {
+		struct pl2303_private *info;
+		unsigned long flags,page;
+		int i;
+
+		info = (struct pl2303_private *)kmalloc (sizeof(struct pl2303_private), GFP_KERNEL);
+		if (info == NULL) {
+			err(__FUNCTION__ " - out of memory");
+			pl2303_close (port, NULL);
+			return -ENOMEM;
+		}
+		spin_lock_init(&info->lock);
+		port->private = info;
+
+
+		page = get_free_page(GFP_KERNEL);
+		if (!page) {
+			pl2303_close (port, NULL);
+			return -ENOMEM;
+		}
+
+		PL2303_LOCK(port,flags);
+
+		info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
+
+		if (tmp_buf)
+			free_page(page);
+		else
+			tmp_buf	= (unsigned char *) page;
+
+		PL2303_UNLOCK(port,flags);
+
+		page = get_free_page(GFP_KERNEL);
+		if (!page) {
+			pl2303_close (port, NULL);
+			return -ENOMEM;
+		}
+
+		PL2303_LOCK(port,flags);
+
+		if (info->xmit_buf)
+			free_page(page);
+		else
+			info->xmit_buf=(unsigned char *) page;
+
+		PL2303_UNLOCK(port,flags);
+
+
+		if ((i = usb_submit_urb (port->read_urb))) {
+			err ("usb_submit_urb(read bulk 1) failed");
+			dbg ("i=%d", i);
+			pl2303_close (port, NULL);
+			return -EPROTO;
+
+		}
+
+		if ((i = usb_submit_urb (port->interrupt_in_urb))) {
+			err ("usb_submit_urb(interrupt ink) failed");
+			dbg ("i=%d", i);
+			pl2303_close (port, NULL);
+
+			return -EPROTO;
+		}
+	}
+
+	return(0);
+}				/* pl2303_open */
+
+
+static void
+pl2303_close (struct usb_serial_port *port, struct file *filp)
+{				/* pl2303_close */
+	struct pl2303_private *info;
+	unsigned int c_cflag = port->tty->termios->c_cflag;
+	unsigned long flags;
+
+	dbg ("pl2303_close port %d", port->number);
+
+	/* shutdown our bulk reads and writes */
+	if (port->active == 1) {
+
+		if (c_cflag & HUPCL) {
+			//FIXME: Do drop DTR
+			//FIXME: Do drop RTS
+		}
+
+		usb_unlink_urb (port->write_urb);
+		usb_unlink_urb (port->read_urb);
+		usb_unlink_urb (port->interrupt_in_urb);
+
+		info = (struct pl2303_private *)port->private;
+		if (info) {
+			PL2303_LOCK(port,flags);
+			if (info->xmit_buf) {
+				unsigned char * temp;
+				temp = info->xmit_buf;
+				info->xmit_buf = 0;
+				free_page((unsigned long) temp);
+			}
+			PL2303_UNLOCK(port,flags);
+		}
+
+		//FIXME: tmp_buf memory leak
+
+
+	}
+	port->active--;
+}				/* pl2303_close */
+
+
+/* do some startup allocations not currently performed by usb_serial_probe() */
+static int
+pl2303_startup (struct usb_serial *serial)
+{
+	return(0);
+}
+
+
+static int
+pl2303_ioctl (struct usb_serial_port *port, struct file *file,
+	      unsigned int cmd, unsigned long arg)
+{
+// struct usb_serial *serial = port->serial;
+// __u16 urb_value=0; /* Will hold the new flags */
+// char buf[1];
+// int  ret, mask;
+
+
+	dbg ("pl2303_sio ioctl 0x%04x", cmd);
+
+	/* Based on code from acm.c and others */
+	switch (cmd) {
+		
+		case TIOCMGET:
+			dbg ("TIOCMGET");
+
+
+			return put_user (0, (unsigned long *) arg);
+			break;
+		case TIOCMBIS:
+		case TIOCMBIC:
+		case TIOCMSET:
+			return 0;
+
+		default:
+			/* This is not an error - turns out the higher layers will do 
+			 *  some ioctls itself (see comment above)
+			 */
+			dbg ("pl2303_sio ioctl arg not supported - it was 0x%04x", cmd);
+			return(-ENOIOCTLCMD);
+			break;
+	}
+	dbg ("pl2303_ioctl returning 0");
+
+	return 0;
+}				/* pl2303_ioctl */
+
+
+static void pl2303_break_ctl(struct usb_serial_port *port,int break_state)
+{
+//FIXME
+}
+
+
+static void
+pl2303_read_int_callback (struct urb *urb)
+{
+	struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
+	struct usb_serial *serial = get_usb_serial (port, "pl2303_read_int_callback");
+	//unsigned char *data = urb->transfer_buffer;
+	//int i;
+
+//ints auto restart...
+
+	if (!serial) {
+		return;
+	}
+
+	if (urb->status) {
+		urb->status = 0;
+		return;
+	}
+
+
+#if 0
+//FIXME need to update state of terminal lines variable
+	if (urb->actual_length) {
+		printk (KERN_DEBUG __FILE__ ": INT data read - length = %d, data = ",
+			urb->actual_length);
+		for (i = 0; i < urb->actual_length; ++i) {
+			printk ("%.2x ", data[i]);
+		}
+		printk ("\n");
+	}
+#endif
+
+	return;
+}
+
+static void
+pl2303_read_bulk_callback (struct urb *urb)
+{
+	struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
+	struct usb_serial *serial = get_usb_serial (port, "pl2303_read_bulk_callback");
+	struct tty_struct *tty;
+	unsigned char *data = urb->transfer_buffer;
+	int i;
+
+	if (!serial) {
+		return;
+	}
+
+// PL2303 mysteriously fails with -EPROTO reschedule the read
+	if (urb->status) {
+		urb->status = 0;
+		if (usb_submit_urb (urb))
+			dbg ("failed resubmitting read bulk urb");
+		return;
+	}
+
+	if (debug) {
+		if (urb->actual_length) {
+			printk (KERN_DEBUG __FILE__ ": BULK data read - length = %d, data = ",
+				urb->actual_length);
+			for (i = 0; i < urb->actual_length; ++i) {
+				printk ("%.2x ", data[i]);
+			}
+			printk ("\n");
+		}
+	}
+
+	tty = port->tty;
+	if (urb->actual_length) {
+		for (i = 0; i < urb->actual_length; ++i) {
+			if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
+				dbg ("ARGH ------------ Flip buffer overrun...");
+
+				break;
+			}
+			tty_insert_flip_char (tty, data[i], 0);
+		}
+		tty_flip_buffer_push (tty);
+	}
+
+
+	/* Schedule the next read*/
+	if (usb_submit_urb (urb))
+		dbg ("failed submitting read bulk urb");
+
+	return;
+}
+
+
+
+static void
+pl2303_write_bulk_callback (struct urb *urb)
+{
+	struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
+	struct usb_serial *serial;
+	struct tty_struct *tty = port->tty;
+
+	dbg ("pl2303_write_bulk_callback");
+
+
+	if (port_paranoia_check (port, "pl2303_write_bulk_callback")) {
+		return;
+	}
+
+	serial = port->serial;
+	if (serial_paranoia_check (serial, "pl2303_write_bulk_callback")) {
+		return;
+	}
+
+
+	if (urb->status) {
+		dbg ("Overflow in write");
+		dbg ("nonzero write bulk status received: %d", urb->status);
+		//need to resubmit frame;
+
+		port->write_urb->transfer_buffer_length = 1;
+
+		//Resubmit ourselves
+
+		if (usb_submit_urb (port->write_urb))
+			err ("usb_submit_urb(write bulk) failed");
+
+		return;
+	}
+
+	wake_up_interruptible (&port->write_wait);
+
+	if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) && tty->ldisc.write_wakeup)
+		(tty->ldisc.write_wakeup) (tty);
+
+	wake_up_interruptible (&tty->write_wait);
+
+	start_xmit(port);
+
+	return;
+}
+
+
+
+static void
+start_xmit (struct usb_serial_port *port)
+{
+	struct usb_serial *serial;
+	struct pl2303_private *info;
+	unsigned long flags;
+
+	serial = port->serial;
+	info = (struct pl2303_private *)port->private;
+
+	if (info) {
+		PL2303_LOCK(port,flags);
+
+		if (port->write_urb->status != -EINPROGRESS) {
+			if (info->xmit_tail != info->xmit_head) {
+
+				memcpy (port->write_urb->transfer_buffer, &info->xmit_buf[info->xmit_tail],1);
+				info->xmit_cnt--;
+				info->xmit_tail = (info->xmit_tail + 1) & (SERIAL_XMIT_SIZE - 1);
+
+
+				port->write_urb->transfer_buffer_length = 1;
+
+
+				if (usb_submit_urb (port->write_urb))
+					err ("usb_submit_urb(write bulk) failed");
+
+
+			}
+		}
+
+		PL2303_UNLOCK(port,flags);
+	}
+}
+
+
+static int __init pl2303_init (void)
+{
+	usb_serial_register (&pl2303_device);
+	info(DRIVER_VERSION " : " DRIVER_DESC);
+	return 0;
+}
+
+
+static void __exit pl2303_exit (void)
+{
+	usb_serial_deregister (&pl2303_device);
+}
+
+
+module_init(pl2303_init);
+module_exit(pl2303_exit);
+
+MODULE_DESCRIPTION(DRIVER_DESC);
+
+MODULE_PARM(debug, "i");
+MODULE_PARM_DESC(debug, "Debug enabled or not");
+