Fedora kernel-2.6.17-1.2142_FC4 patched with stable patch-2.6.17.4-vs2.0.2-rc26.diff
[linux-2.6.git] / drivers / usb / serial / pl2303.c
index c61e568..c96714b 100644 (file)
@@ -8,31 +8,10 @@
  *
  *     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.
+ *     the Free Software Foundation; either version 2 of the License.
  *
  * See Documentation/usb/usb-serial.txt for more information on using this driver
  *
- * 2002_Mar_26 gkh
- *     allowed driver to work properly if there is no tty assigned to a port
- *     (this happens for serial console devices.)
- *
- * 2001_Oct_06 gkh
- *     Added RTS and DTR line control.  Thanks to joe@bndlg.de for parts of it.
- *
- * 2001_Sep_19 gkh
- *     Added break support.
- *
- * 2001_Aug_30 gkh
- *     fixed oops in write_bulk_callback.
- *
- * 2001_Aug_28 gkh
- *     reworked buffer logic to be like other usb-serial drivers.  Hopefully
- *     removing some reported problems.
- *
- * 2001_Jun_06 gkh
- *     finished porting to 2.4 format.
- * 
  */
 
 #include <linux/config.h>
 /*
  * Version Information
  */
-#define DRIVER_VERSION "v0.11"
 #define DRIVER_DESC "Prolific PL2303 USB to serial adaptor driver"
 
 static int debug;
 
+#define PL2303_CLOSING_WAIT    (30*HZ)
+
+#define PL2303_BUF_SIZE                1024
+#define PL2303_TMP_BUF_SIZE    1024
+
+struct pl2303_buf {
+       unsigned int    buf_size;
+       char            *buf_buf;
+       char            *buf_get;
+       char            *buf_put;
+};
+
 static struct usb_device_id id_table [] = {
        { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID) },
        { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_RSAQ2) },
+       { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_RSAQ3) },
+       { USB_DEVICE(PL2303_VENDOR_ID, PL2303_PRODUCT_ID_PHAROS) },
        { USB_DEVICE(IODATA_VENDOR_ID, IODATA_PRODUCT_ID) },
        { USB_DEVICE(ATEN_VENDOR_ID, ATEN_PRODUCT_ID) },
        { USB_DEVICE(ATEN_VENDOR_ID2, ATEN_PRODUCT_ID) },
        { USB_DEVICE(ELCOM_VENDOR_ID, ELCOM_PRODUCT_ID) },
+       { USB_DEVICE(ELCOM_VENDOR_ID, ELCOM_PRODUCT_ID_UCSGT) },
        { USB_DEVICE(ITEGNO_VENDOR_ID, ITEGNO_PRODUCT_ID) },
+       { USB_DEVICE(ITEGNO_VENDOR_ID, ITEGNO_PRODUCT_ID_2080) },
        { USB_DEVICE(MA620_VENDOR_ID, MA620_PRODUCT_ID) },
        { USB_DEVICE(RATOC_VENDOR_ID, RATOC_PRODUCT_ID) },
        { USB_DEVICE(TRIPP_VENDOR_ID, TRIPP_PRODUCT_ID) },
@@ -76,17 +70,27 @@ static struct usb_device_id id_table [] = {
        { USB_DEVICE(SITECOM_VENDOR_ID, SITECOM_PRODUCT_ID) },
        { USB_DEVICE(ALCATEL_VENDOR_ID, ALCATEL_PRODUCT_ID) },
        { USB_DEVICE(SAMSUNG_VENDOR_ID, SAMSUNG_PRODUCT_ID) },
+       { USB_DEVICE(SIEMENS_VENDOR_ID, SIEMENS_PRODUCT_ID_SX1) },
+       { USB_DEVICE(SIEMENS_VENDOR_ID, SIEMENS_PRODUCT_ID_X65) },
+       { USB_DEVICE(SIEMENS_VENDOR_ID, SIEMENS_PRODUCT_ID_X75) },
+       { USB_DEVICE(SYNTECH_VENDOR_ID, SYNTECH_PRODUCT_ID) },
+       { USB_DEVICE(NOKIA_CA42_VENDOR_ID, NOKIA_CA42_PRODUCT_ID) },
+       { USB_DEVICE(CA_42_CA42_VENDOR_ID, CA_42_CA42_PRODUCT_ID) },
+       { USB_DEVICE(SAGEM_VENDOR_ID, SAGEM_PRODUCT_ID) },
+       { USB_DEVICE(LEADTEK_VENDOR_ID, LEADTEK_9531_PRODUCT_ID) },
+       { USB_DEVICE(SPEEDDRAGON_VENDOR_ID, SPEEDDRAGON_PRODUCT_ID) },
+       { USB_DEVICE(OTI_VENDOR_ID, OTI_PRODUCT_ID) },
        { }                                     /* Terminating entry */
 };
 
 MODULE_DEVICE_TABLE (usb, id_table);
 
 static struct usb_driver pl2303_driver = {
-       .owner =        THIS_MODULE,
        .name =         "pl2303",
        .probe =        usb_serial_probe,
        .disconnect =   usb_serial_disconnect,
        .id_table =     id_table,
+       .no_dynamic_id =        1,
 };
 
 #define SET_LINE_REQUEST_TYPE          0x21
@@ -132,20 +136,34 @@ static int pl2303_ioctl (struct usb_serial_port *port, struct file *file,
 static void pl2303_read_int_callback (struct urb *urb, struct pt_regs *regs);
 static void pl2303_read_bulk_callback (struct urb *urb, struct pt_regs *regs);
 static void pl2303_write_bulk_callback (struct urb *urb, struct pt_regs *regs);
-static int pl2303_write (struct usb_serial_port *port, int from_user,
+static int pl2303_write (struct usb_serial_port *port,
                         const unsigned char *buf, int count);
+static void pl2303_send (struct usb_serial_port *port);
+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 int pl2303_tiocmget (struct usb_serial_port *port, struct file *file);
 static int pl2303_tiocmset (struct usb_serial_port *port, struct file *file,
                            unsigned int set, unsigned int clear);
 static int pl2303_startup (struct usb_serial *serial);
 static void pl2303_shutdown (struct usb_serial *serial);
+static struct pl2303_buf *pl2303_buf_alloc(unsigned int size);
+static void pl2303_buf_free(struct pl2303_buf *pb);
+static void pl2303_buf_clear(struct pl2303_buf *pb);
+static unsigned int pl2303_buf_data_avail(struct pl2303_buf *pb);
+static unsigned int pl2303_buf_space_avail(struct pl2303_buf *pb);
+static unsigned int pl2303_buf_put(struct pl2303_buf *pb, const char *buf,
+       unsigned int count);
+static unsigned int pl2303_buf_get(struct pl2303_buf *pb, char *buf,
+       unsigned int count);
 
 
 /* All of the device info needed for the PL2303 SIO serial converter */
-static struct usb_serial_device_type pl2303_device = {
-       .owner =                THIS_MODULE,
-       .name =                 "PL-2303",
+static struct usb_serial_driver pl2303_device = {
+       .driver = {
+               .owner =        THIS_MODULE,
+               .name =         "pl2303",
+       },
        .id_table =             id_table,
        .num_interrupt_in =     NUM_DONT_CARE,
        .num_bulk_in =          1,
@@ -162,6 +180,8 @@ static struct usb_serial_device_type pl2303_device = {
        .read_bulk_callback =   pl2303_read_bulk_callback,
        .read_int_callback =    pl2303_read_int_callback,
        .write_bulk_callback =  pl2303_write_bulk_callback,
+       .write_room =           pl2303_write_room,
+       .chars_in_buffer =      pl2303_chars_in_buffer,
        .attach =               pl2303_startup,
        .shutdown =             pl2303_shutdown,
 };
@@ -174,6 +194,8 @@ enum pl2303_type {
 
 struct pl2303_private {
        spinlock_t lock;
+       struct pl2303_buf *buf;
+       int write_urb_in_use;
        wait_queue_head_t delta_msr_wait;
        u8 line_control;
        u8 line_status;
@@ -199,16 +221,29 @@ static int pl2303_startup (struct usb_serial *serial)
        dbg("device type: %d", type);
 
        for (i = 0; i < serial->num_ports; ++i) {
-               priv = kmalloc (sizeof (struct pl2303_private), GFP_KERNEL);
+               priv = kzalloc(sizeof(struct pl2303_private), GFP_KERNEL);
                if (!priv)
-                       return -ENOMEM;
-               memset (priv, 0x00, sizeof (struct pl2303_private));
+                       goto cleanup;
                spin_lock_init(&priv->lock);
+               priv->buf = pl2303_buf_alloc(PL2303_BUF_SIZE);
+               if (priv->buf == NULL) {
+                       kfree(priv);
+                       goto cleanup;
+               }
                init_waitqueue_head(&priv->delta_msr_wait);
                priv->type = type;
                usb_set_serial_port_data(serial->port[i], priv);
        }
        return 0;
+
+cleanup:
+       for (--i; i>=0; --i) {
+               priv = usb_get_serial_port_data(serial->port[i]);
+               pl2303_buf_free(priv->buf);
+               kfree(priv);
+               usb_set_serial_port_data(serial->port[i], NULL);
+       }
+       return -ENOMEM;
 }
 
 static int set_control_lines (struct usb_device *dev, u8 value)
@@ -222,42 +257,97 @@ static int set_control_lines (struct usb_device *dev, u8 value)
        return retval;
 }
 
-static int pl2303_write (struct usb_serial_port *port, int from_user,  const unsigned char *buf, int count)
+static int pl2303_write (struct usb_serial_port *port,  const unsigned char *buf, int count)
 {
-       int result;
+       struct pl2303_private *priv = usb_get_serial_port_data(port);
+       unsigned long flags;
 
        dbg("%s - port %d, %d bytes", __FUNCTION__, port->number, count);
 
        if (!count)
                return count;
 
-       if (port->write_urb->status == -EINPROGRESS) {
-               dbg("%s - already writing", __FUNCTION__);
-               return 0;
+       spin_lock_irqsave(&priv->lock, flags);
+       count = pl2303_buf_put(priv->buf, buf, count);
+       spin_unlock_irqrestore(&priv->lock, flags);
+
+       pl2303_send(port);
+
+       return count;
+}
+
+static void pl2303_send(struct usb_serial_port *port)
+{
+       int count, result;
+       struct pl2303_private *priv = usb_get_serial_port_data(port);
+       unsigned long flags;
+
+       dbg("%s - port %d", __FUNCTION__, port->number);
+
+       spin_lock_irqsave(&priv->lock, flags);
+
+       if (priv->write_urb_in_use) {
+               spin_unlock_irqrestore(&priv->lock, flags);
+               return;
        }
 
-       count = (count > port->bulk_out_size) ? port->bulk_out_size : count;
-       if (from_user) {
-               if (copy_from_user (port->write_urb->transfer_buffer, buf, count))
-                       return -EFAULT;
-       } else {
-               memcpy (port->write_urb->transfer_buffer, buf, count);
+       count = pl2303_buf_get(priv->buf, port->write_urb->transfer_buffer,
+               port->bulk_out_size);
+
+       if (count == 0) {
+               spin_unlock_irqrestore(&priv->lock, flags);
+               return;
        }
-       
+
+       priv->write_urb_in_use = 1;
+
+       spin_unlock_irqrestore(&priv->lock, flags);
+
        usb_serial_debug_data(debug, &port->dev, __FUNCTION__, count, port->write_urb->transfer_buffer);
 
        port->write_urb->transfer_buffer_length = count;
        port->write_urb->dev = port->serial->dev;
        result = usb_submit_urb (port->write_urb, GFP_ATOMIC);
-       if (result)
+       if (result) {
                dev_err(&port->dev, "%s - failed submitting write urb, error %d\n", __FUNCTION__, result);
-       else
-               result = count;
+               priv->write_urb_in_use = 0;
+               // TODO: reschedule pl2303_send
+       }
 
-       return result;
+       schedule_work(&port->work);
+}
+
+static int pl2303_write_room(struct usb_serial_port *port)
+{
+       struct pl2303_private *priv = usb_get_serial_port_data(port);
+       int room = 0;
+       unsigned long flags;
+
+       dbg("%s - port %d", __FUNCTION__, port->number);
+
+       spin_lock_irqsave(&priv->lock, flags);
+       room = pl2303_buf_space_avail(priv->buf);
+       spin_unlock_irqrestore(&priv->lock, flags);
+
+       dbg("%s - returns %d", __FUNCTION__, room);
+       return room;
 }
 
+static int pl2303_chars_in_buffer(struct usb_serial_port *port)
+{
+       struct pl2303_private *priv = usb_get_serial_port_data(port);
+       int chars = 0;
+       unsigned long flags;
+
+       dbg("%s - port %d", __FUNCTION__, port->number);
 
+       spin_lock_irqsave(&priv->lock, flags);
+       chars = pl2303_buf_data_avail(priv->buf);
+       spin_unlock_irqrestore(&priv->lock, flags);
+
+       dbg("%s - returns %d", __FUNCTION__, chars);
+       return chars;
+}
 
 static void pl2303_set_termios (struct usb_serial_port *port, struct termios *old_termios)
 {
@@ -295,12 +385,11 @@ static void pl2303_set_termios (struct usb_serial_port *port, struct termios *ol
                }
        }
 
-       buf = kmalloc (7, GFP_KERNEL);
+       buf = kzalloc (7, GFP_KERNEL);
        if (!buf) {
                dev_err(&port->dev, "%s - out of memory.\n", __FUNCTION__);
                return;
        }
-       memset (buf, 0x00, 0x07);
        
        i = usb_control_msg (serial->dev, usb_rcvctrlpipe (serial->dev, 0),
                             GET_LINE_REQUEST, GET_LINE_REQUEST_TYPE,
@@ -422,7 +511,7 @@ static void pl2303_set_termios (struct usb_serial_port *port, struct termios *ol
        }
 
        kfree (buf);
-} 
+}
 
 static int pl2303_open (struct usb_serial_port *port, struct file *filp)
 {
@@ -434,8 +523,10 @@ static int pl2303_open (struct usb_serial_port *port, struct file *filp)
 
        dbg("%s -  port %d", __FUNCTION__, port->number);
 
-       usb_clear_halt(serial->dev, port->write_urb->pipe);
-       usb_clear_halt(serial->dev, port->read_urb->pipe);
+       if (priv->type != HX) {
+               usb_clear_halt(serial->dev, port->write_urb->pipe);
+               usb_clear_halt(serial->dev, port->read_urb->pipe);
+       }
 
        buf = kmalloc(10, GFP_KERNEL);
        if (buf==NULL)
@@ -461,7 +552,7 @@ static int pl2303_open (struct usb_serial_port *port, struct file *filp)
        FISH (VENDOR_READ_REQUEST_TYPE, VENDOR_READ_REQUEST, 0x8383, 0);
        SOUP (VENDOR_WRITE_REQUEST_TYPE, VENDOR_WRITE_REQUEST, 0, 1);
        SOUP (VENDOR_WRITE_REQUEST_TYPE, VENDOR_WRITE_REQUEST, 1, 0);
+
        if (priv->type == HX) {
                /* HX chip */
                SOUP (VENDOR_WRITE_REQUEST_TYPE, VENDOR_WRITE_REQUEST, 2, 0x44);
@@ -504,45 +595,66 @@ static int pl2303_open (struct usb_serial_port *port, struct file *filp)
 
 static void pl2303_close (struct usb_serial_port *port, struct file *filp)
 {
-       struct pl2303_private *priv;
+       struct pl2303_private *priv = usb_get_serial_port_data(port);
        unsigned long flags;
        unsigned int c_cflag;
-       int result;
+       int bps;
+       long timeout;
+       wait_queue_t wait;                                              \
 
        dbg("%s - port %d", __FUNCTION__, port->number);
 
-       /* shutdown our urbs */
-       dbg("%s - shutting down urbs", __FUNCTION__);
-       result = usb_unlink_urb (port->write_urb);
-       if (result)
-               dbg("%s - usb_unlink_urb (write_urb)"
-                   " failed with reason: %d", __FUNCTION__,
-                    result);
+       /* wait for data to drain from the buffer */
+       spin_lock_irqsave(&priv->lock, flags);
+       timeout = PL2303_CLOSING_WAIT;
+       init_waitqueue_entry(&wait, current);
+       add_wait_queue(&port->tty->write_wait, &wait);
+       for (;;) {
+               set_current_state(TASK_INTERRUPTIBLE);
+               if (pl2303_buf_data_avail(priv->buf) == 0
+               || timeout == 0 || signal_pending(current)
+               || !usb_get_intfdata(port->serial->interface))  /* disconnect */
+                       break;
+               spin_unlock_irqrestore(&priv->lock, flags);
+               timeout = schedule_timeout(timeout);
+               spin_lock_irqsave(&priv->lock, flags);
+       }
+       set_current_state(TASK_RUNNING);
+       remove_wait_queue(&port->tty->write_wait, &wait);
+       /* clear out any remaining data in the buffer */
+       pl2303_buf_clear(priv->buf);
+       spin_unlock_irqrestore(&priv->lock, flags);
 
-       result = usb_unlink_urb (port->read_urb);
-       if (result)
-               dbg("%s - usb_unlink_urb (read_urb) "
-                   "failed with reason: %d", __FUNCTION__,
-                    result);
+       /* wait for characters to drain from the device */
+       /* (this is long enough for the entire 256 byte */
+       /* pl2303 hardware buffer to drain with no flow */
+       /* control for data rates of 1200 bps or more, */
+       /* for lower rates we should really know how much */
+       /* data is in the buffer to compute a delay */
+       /* that is not unnecessarily long) */
+       bps = tty_get_baud_rate(port->tty);
+       if (bps > 1200)
+               timeout = max((HZ*2560)/bps,HZ/10);
+       else
+               timeout = 2*HZ;
+       schedule_timeout_interruptible(timeout);
 
-       result = usb_unlink_urb (port->interrupt_in_urb);
-       if (result)
-               dbg("%s - usb_unlink_urb (interrupt_in_urb)"
-                   " failed with reason: %d", __FUNCTION__,
-                    result);
+       /* shutdown our urbs */
+       dbg("%s - shutting down urbs", __FUNCTION__);
+       usb_kill_urb(port->write_urb);
+       usb_kill_urb(port->read_urb);
+       usb_kill_urb(port->interrupt_in_urb);
 
        if (port->tty) {
                c_cflag = port->tty->termios->c_cflag;
                if (c_cflag & HUPCL) {
                        /* drop DTR and RTS */
-                       priv = usb_get_serial_port_data(port);
                        spin_lock_irqsave(&priv->lock, flags);
                        priv->line_control = 0;
                        spin_unlock_irqrestore (&priv->lock, flags);
                        set_control_lines (port->serial->dev, 0);
                }
        }
-
 }
 
 static int pl2303_tiocmset (struct usb_serial_port *port, struct file *file,
@@ -552,6 +664,9 @@ static int pl2303_tiocmset (struct usb_serial_port *port, struct file *file,
        unsigned long flags;
        u8 control;
 
+       if (!usb_get_intfdata(port->serial->interface))
+               return -ENODEV;
+
        spin_lock_irqsave (&priv->lock, flags);
        if (set & TIOCM_RTS)
                priv->line_control |= CONTROL_RTS;
@@ -577,6 +692,9 @@ static int pl2303_tiocmget (struct usb_serial_port *port, struct file *file)
 
        dbg("%s (%d)", __FUNCTION__, port->number);
 
+       if (!usb_get_intfdata(port->serial->interface))
+               return -ENODEV;
+
        spin_lock_irqsave (&priv->lock, flags);
        mcr = priv->line_control;
        status = priv->line_status;
@@ -672,24 +790,57 @@ static void pl2303_break_ctl (struct usb_serial_port *port, int break_state)
 static void pl2303_shutdown (struct usb_serial *serial)
 {
        int i;
+       struct pl2303_private *priv;
 
        dbg("%s", __FUNCTION__);
 
        for (i = 0; i < serial->num_ports; ++i) {
-               kfree (usb_get_serial_port_data(serial->port[i]));
-               usb_set_serial_port_data(serial->port[i], NULL);
+               priv = usb_get_serial_port_data(serial->port[i]);
+               if (priv) {
+                       pl2303_buf_free(priv->buf);
+                       kfree(priv);
+                       usb_set_serial_port_data(serial->port[i], NULL);
+               }
        }               
 }
 
+static void pl2303_update_line_status(struct usb_serial_port *port,
+                                     unsigned char *data,
+                                     unsigned int actual_length)
+{
+
+       struct pl2303_private *priv = usb_get_serial_port_data(port);
+       unsigned long flags;
+       u8 status_idx = UART_STATE;
+       u8 length = UART_STATE + 1;
+
+       if ((le16_to_cpu(port->serial->dev->descriptor.idVendor) == SIEMENS_VENDOR_ID) &&
+           (le16_to_cpu(port->serial->dev->descriptor.idProduct) == SIEMENS_PRODUCT_ID_X65 ||
+            le16_to_cpu(port->serial->dev->descriptor.idProduct) == SIEMENS_PRODUCT_ID_SX1 ||
+            le16_to_cpu(port->serial->dev->descriptor.idProduct) == SIEMENS_PRODUCT_ID_X75)) {
+               length = 1;
+               status_idx = 0;
+       }
+
+       if (actual_length < length)
+               goto exit;
+
+        /* Save off the uart status for others to look at */
+       spin_lock_irqsave(&priv->lock, flags);
+       priv->line_status = data[status_idx];
+       spin_unlock_irqrestore(&priv->lock, flags);
+       wake_up_interruptible (&priv->delta_msr_wait);
+
+exit:
+       return;
+}
 
 static void pl2303_read_int_callback (struct urb *urb, struct pt_regs *regs)
 {
        struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
-       struct pl2303_private *priv = usb_get_serial_port_data(port);
        unsigned char *data = urb->transfer_buffer;
-       unsigned long flags;
+       unsigned int actual_length = urb->actual_length;
        int status;
-       u8 uart_state;
 
        dbg("%s (%d)", __FUNCTION__, port->number);
 
@@ -708,19 +859,9 @@ static void pl2303_read_int_callback (struct urb *urb, struct pt_regs *regs)
                goto exit;
        }
 
-
        usb_serial_debug_data(debug, &port->dev, __FUNCTION__, urb->actual_length, urb->transfer_buffer);
+       pl2303_update_line_status(port, data, actual_length);
 
-       if (urb->actual_length < UART_STATE)
-               goto exit;
-
-       /* Save off the uart status for others to look at */
-       uart_state = data[UART_STATE];
-       spin_lock_irqsave(&priv->lock, flags);
-       uart_state |= (priv->line_status & UART_STATE_TRANSIENT_MASK);
-       priv->line_status = uart_state;
-       spin_unlock_irqrestore(&priv->lock, flags);
-               
 exit:
        status = usb_submit_urb (urb, GFP_ATOMIC);
        if (status)
@@ -786,16 +927,12 @@ static void pl2303_read_bulk_callback (struct urb *urb, struct pt_regs *regs)
 
        tty = port->tty;
        if (tty && urb->actual_length) {
+               tty_buffer_request_room(tty, urb->actual_length + 1);
                /* overrun is special, not associated with a char */
                if (status & UART_OVERRUN_ERROR)
                        tty_insert_flip_char(tty, 0, TTY_OVERRUN);
-
-               for (i = 0; i < urb->actual_length; ++i) {
-                       if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
-                               tty_flip_buffer_push(tty);
-                       }
+               for (i = 0; i < urb->actual_length; ++i)
                        tty_insert_flip_char (tty, data[i], tty_flag);
-               }
                tty_flip_buffer_push (tty);
        }
 
@@ -815,11 +952,23 @@ static void pl2303_read_bulk_callback (struct urb *urb, struct pt_regs *regs)
 static void pl2303_write_bulk_callback (struct urb *urb, struct pt_regs *regs)
 {
        struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
+       struct pl2303_private *priv = usb_get_serial_port_data(port);
        int result;
 
        dbg("%s - port %d", __FUNCTION__, port->number);
-       
-       if (urb->status) {
+
+       switch (urb->status) {
+       case 0:
+               /* success */
+               break;
+       case -ECONNRESET:
+       case -ENOENT:
+       case -ESHUTDOWN:
+               /* this urb is terminated, clean up */
+               dbg("%s - urb shutting down with status: %d", __FUNCTION__, urb->status);
+               priv->write_urb_in_use = 0;
+               return;
+       default:
                /* error in the urb, so we have to resubmit it */
                dbg("%s - Overflow in write", __FUNCTION__);
                dbg("%s - nonzero write bulk status received: %d", __FUNCTION__, urb->status);
@@ -828,14 +977,198 @@ static void pl2303_write_bulk_callback (struct urb *urb, struct pt_regs *regs)
                result = usb_submit_urb (port->write_urb, GFP_ATOMIC);
                if (result)
                        dev_err(&urb->dev->dev, "%s - failed resubmitting write urb, error %d\n", __FUNCTION__, result);
+               else
+                       return;
+       }
 
-               return;
+       priv->write_urb_in_use = 0;
+
+       /* send any buffered data */
+       pl2303_send(port);
+}
+
+
+/*
+ * pl2303_buf_alloc
+ *
+ * Allocate a circular buffer and all associated memory.
+ */
+
+static struct pl2303_buf *pl2303_buf_alloc(unsigned int size)
+{
+
+       struct pl2303_buf *pb;
+
+
+       if (size == 0)
+               return NULL;
+
+       pb = (struct pl2303_buf *)kmalloc(sizeof(struct pl2303_buf), GFP_KERNEL);
+       if (pb == NULL)
+               return NULL;
+
+       pb->buf_buf = kmalloc(size, GFP_KERNEL);
+       if (pb->buf_buf == NULL) {
+               kfree(pb);
+               return NULL;
        }
 
-       schedule_work(&port->work);
+       pb->buf_size = size;
+       pb->buf_get = pb->buf_put = pb->buf_buf;
+
+       return pb;
+
+}
+
+
+/*
+ * pl2303_buf_free
+ *
+ * Free the buffer and all associated memory.
+ */
+
+static void pl2303_buf_free(struct pl2303_buf *pb)
+{
+       if (pb) {
+               kfree(pb->buf_buf);
+               kfree(pb);
+       }
+}
+
+
+/*
+ * pl2303_buf_clear
+ *
+ * Clear out all data in the circular buffer.
+ */
+
+static void pl2303_buf_clear(struct pl2303_buf *pb)
+{
+       if (pb != NULL)
+               pb->buf_get = pb->buf_put;
+               /* equivalent to a get of all data available */
+}
+
+
+/*
+ * pl2303_buf_data_avail
+ *
+ * Return the number of bytes of data available in the circular
+ * buffer.
+ */
+
+static unsigned int pl2303_buf_data_avail(struct pl2303_buf *pb)
+{
+       if (pb != NULL)
+               return ((pb->buf_size + pb->buf_put - pb->buf_get) % pb->buf_size);
+       else
+               return 0;
+}
+
+
+/*
+ * pl2303_buf_space_avail
+ *
+ * Return the number of bytes of space available in the circular
+ * buffer.
+ */
+
+static unsigned int pl2303_buf_space_avail(struct pl2303_buf *pb)
+{
+       if (pb != NULL)
+               return ((pb->buf_size + pb->buf_get - pb->buf_put - 1) % pb->buf_size);
+       else
+               return 0;
+}
+
+
+/*
+ * pl2303_buf_put
+ *
+ * Copy data data from a user buffer and put it into the circular buffer.
+ * Restrict to the amount of space available.
+ *
+ * Return the number of bytes copied.
+ */
+
+static unsigned int pl2303_buf_put(struct pl2303_buf *pb, const char *buf,
+       unsigned int count)
+{
+
+       unsigned int len;
+
+
+       if (pb == NULL)
+               return 0;
+
+       len  = pl2303_buf_space_avail(pb);
+       if (count > len)
+               count = len;
+
+       if (count == 0)
+               return 0;
+
+       len = pb->buf_buf + pb->buf_size - pb->buf_put;
+       if (count > len) {
+               memcpy(pb->buf_put, buf, len);
+               memcpy(pb->buf_buf, buf+len, count - len);
+               pb->buf_put = pb->buf_buf + count - len;
+       } else {
+               memcpy(pb->buf_put, buf, count);
+               if (count < len)
+                       pb->buf_put += count;
+               else /* count == len */
+                       pb->buf_put = pb->buf_buf;
+       }
+
+       return count;
+
 }
 
 
+/*
+ * pl2303_buf_get
+ *
+ * Get data from the circular buffer and copy to the given buffer.
+ * Restrict to the amount of data available.
+ *
+ * Return the number of bytes copied.
+ */
+
+static unsigned int pl2303_buf_get(struct pl2303_buf *pb, char *buf,
+       unsigned int count)
+{
+
+       unsigned int len;
+
+
+       if (pb == NULL)
+               return 0;
+
+       len = pl2303_buf_data_avail(pb);
+       if (count > len)
+               count = len;
+
+       if (count == 0)
+               return 0;
+
+       len = pb->buf_buf + pb->buf_size - pb->buf_get;
+       if (count > len) {
+               memcpy(buf, pb->buf_get, len);
+               memcpy(buf+len, pb->buf_buf, count - len);
+               pb->buf_get = pb->buf_buf + count - len;
+       } else {
+               memcpy(buf, pb->buf_get, count);
+               if (count < len)
+                       pb->buf_get += count;
+               else /* count == len */
+                       pb->buf_get = pb->buf_buf;
+       }
+
+       return count;
+
+}
+
 static int __init pl2303_init (void)
 {
        int retval;
@@ -845,7 +1178,7 @@ static int __init pl2303_init (void)
        retval = usb_register(&pl2303_driver);
        if (retval)
                goto failed_usb_register;
-       info(DRIVER_DESC " " DRIVER_VERSION);
+       info(DRIVER_DESC);
        return 0;
 failed_usb_register:
        usb_serial_deregister(&pl2303_device);