USB: RTS/CTS handshaking support, DTR fixes for MCT U232 serial adapter
Improvements and fixes to the MCT U232 USB/serial interface driver.
Implement RTS/CTS hardware flow control. Implement HUPCL. Bring
handling of DTR and RTS into conformance with other Linux serial
port drivers - assert both signals when opening device, even if
"crtscts" is not currently selected.
Signed-off-by: Dave Platt <dplatt@radagast.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/usb/serial/mct_u232.c b/drivers/usb/serial/mct_u232.c
index 3db1adc..204f0f9 100644
--- a/drivers/usb/serial/mct_u232.c
+++ b/drivers/usb/serial/mct_u232.c
@@ -81,7 +81,7 @@
/*
* Version Information
*/
-#define DRIVER_VERSION "z2.0" /* Linux in-kernel version */
+#define DRIVER_VERSION "z2.1" /* Linux in-kernel version */
#define DRIVER_AUTHOR "Wolfgang Grandegger <wolfgang@ces.ch>"
#define DRIVER_DESC "Magic Control Technology USB-RS232 converter driver"
@@ -110,6 +110,10 @@
static int mct_u232_tiocmset (struct usb_serial_port *port,
struct file *file, unsigned int set,
unsigned int clear);
+static void mct_u232_throttle (struct usb_serial_port *port);
+static void mct_u232_unthrottle (struct usb_serial_port *port);
+
+
/*
* All of the device info needed for the MCT USB-RS232 converter.
*/
@@ -145,6 +149,8 @@
.num_ports = 1,
.open = mct_u232_open,
.close = mct_u232_close,
+ .throttle = mct_u232_throttle,
+ .unthrottle = mct_u232_unthrottle,
.read_int_callback = mct_u232_read_int_callback,
.ioctl = mct_u232_ioctl,
.set_termios = mct_u232_set_termios,
@@ -162,8 +168,11 @@
unsigned char last_lcr; /* Line Control Register */
unsigned char last_lsr; /* Line Status Register */
unsigned char last_msr; /* Modem Status Register */
+ unsigned int rx_flags; /* Throttling flags */
};
+#define THROTTLED 0x01
+
/*
* Handle vendor specific USB requests
*/
@@ -216,11 +225,13 @@
}
}
-static int mct_u232_set_baud_rate(struct usb_serial *serial, int value)
+static int mct_u232_set_baud_rate(struct usb_serial *serial, struct usb_serial_port *port,
+ int value)
{
__le32 divisor;
int rc;
unsigned char zero_byte = 0;
+ unsigned char cts_enable_byte = 0;
divisor = cpu_to_le32(mct_u232_calculate_baud_rate(serial, value));
@@ -238,10 +249,17 @@
'baud rate change' message. The actual functionality of the
request codes in these messages is not fully understood but these
particular codes are never seen in any operation besides a baud
- rate change. Both of these messages send a single byte of data
- whose value is always zero. The second of these two extra messages
- is required in order for data to be properly written to an RS-232
- device which does not assert the 'CTS' signal. */
+ rate change. Both of these messages send a single byte of data.
+ In the first message, the value of this byte is always zero.
+
+ The second message has been determined experimentally to control
+ whether data will be transmitted to a device which is not asserting
+ the 'CTS' signal. If the second message's data byte is zero, data
+ will be transmitted even if 'CTS' is not asserted (i.e. no hardware
+ flow control). if the second message's data byte is nonzero (a value
+ of 1 is used by this driver), data will not be transmitted to a device
+ which is not asserting 'CTS'.
+ */
rc = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
MCT_U232_SET_UNKNOWN1_REQUEST,
@@ -252,14 +270,19 @@
err("Sending USB device request code %d failed (error = %d)",
MCT_U232_SET_UNKNOWN1_REQUEST, rc);
+ if (port && C_CRTSCTS(port->tty)) {
+ cts_enable_byte = 1;
+ }
+
+ dbg("set_baud_rate: send second control message, data = %02X", cts_enable_byte);
rc = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
- MCT_U232_SET_UNKNOWN2_REQUEST,
+ MCT_U232_SET_CTS_REQUEST,
MCT_U232_SET_REQUEST_TYPE,
- 0, 0, &zero_byte, MCT_U232_SET_UNKNOWN2_SIZE,
+ 0, 0, &cts_enable_byte, MCT_U232_SET_CTS_SIZE,
WDR_TIMEOUT);
if (rc < 0)
- err("Sending USB device request code %d failed (error = %d)",
- MCT_U232_SET_UNKNOWN2_REQUEST, rc);
+ err("Sending USB device request code %d failed (error = %d)",
+ MCT_U232_SET_CTS_REQUEST, rc);
return rc;
} /* mct_u232_set_baud_rate */
@@ -458,8 +481,25 @@
static void mct_u232_close (struct usb_serial_port *port, struct file *filp)
{
+ unsigned int c_cflag;
+ unsigned long flags;
+ unsigned int control_state;
+ struct mct_u232_private *priv = usb_get_serial_port_data(port);
dbg("%s port %d", __FUNCTION__, port->number);
+ if (port->tty) {
+ c_cflag = port->tty->termios->c_cflag;
+ if (c_cflag & HUPCL) {
+ /* drop DTR and RTS */
+ spin_lock_irqsave(&priv->lock, flags);
+ priv->control_state &= ~(TIOCM_DTR | TIOCM_RTS);
+ control_state = priv->control_state;
+ spin_unlock_irqrestore(&priv->lock, flags);
+ mct_u232_set_modem_ctrl(port->serial, control_state);
+ }
+ }
+
+
if (port->serial->dev) {
/* shutdown our urbs */
usb_kill_urb(port->write_urb);
@@ -565,11 +605,10 @@
{
struct usb_serial *serial = port->serial;
struct mct_u232_private *priv = usb_get_serial_port_data(port);
- unsigned int iflag = port->tty->termios->c_iflag;
unsigned int cflag = port->tty->termios->c_cflag;
unsigned int old_cflag = old_termios->c_cflag;
unsigned long flags;
- unsigned int control_state, new_state;
+ unsigned int control_state;
unsigned char last_lcr;
/* get a local copy of the current port settings */
@@ -585,18 +624,14 @@
* Premature optimization is the root of all evil.
*/
- /* reassert DTR and (maybe) RTS on transition from B0 */
+ /* reassert DTR and RTS on transition from B0 */
if ((old_cflag & CBAUD) == B0) {
dbg("%s: baud was B0", __FUNCTION__);
- control_state |= TIOCM_DTR;
- /* don't set RTS if using hardware flow control */
- if (!(old_cflag & CRTSCTS)) {
- control_state |= TIOCM_RTS;
- }
+ control_state |= TIOCM_DTR | TIOCM_RTS;
mct_u232_set_modem_ctrl(serial, control_state);
}
- mct_u232_set_baud_rate(serial, cflag & CBAUD);
+ mct_u232_set_baud_rate(serial, port, cflag & CBAUD);
if ((cflag & CBAUD) == B0 ) {
dbg("%s: baud is B0", __FUNCTION__);
@@ -638,21 +673,6 @@
mct_u232_set_line_ctrl(serial, last_lcr);
- /*
- * Set flow control: well, I do not really now how to handle DTR/RTS.
- * Just do what we have seen with SniffUSB on Win98.
- */
- /* Drop DTR/RTS if no flow control otherwise assert */
- new_state = control_state;
- if ((iflag & IXOFF) || (iflag & IXON) || (cflag & CRTSCTS))
- new_state |= TIOCM_DTR | TIOCM_RTS;
- else
- new_state &= ~(TIOCM_DTR | TIOCM_RTS);
- if (new_state != control_state) {
- mct_u232_set_modem_ctrl(serial, new_state);
- control_state = new_state;
- }
-
/* save off the modified port settings */
spin_lock_irqsave(&priv->lock, flags);
priv->control_state = control_state;
@@ -747,6 +767,50 @@
return 0;
} /* mct_u232_ioctl */
+static void mct_u232_throttle (struct usb_serial_port *port)
+{
+ struct mct_u232_private *priv = usb_get_serial_port_data(port);
+ unsigned long flags;
+ unsigned int control_state;
+ struct tty_struct *tty;
+
+ tty = port->tty;
+ dbg("%s - port %d", __FUNCTION__, port->number);
+
+ spin_lock_irqsave(&priv->lock, flags);
+ priv->rx_flags |= THROTTLED;
+ if (C_CRTSCTS(tty)) {
+ priv->control_state &= ~TIOCM_RTS;
+ control_state = priv->control_state;
+ spin_unlock_irqrestore(&priv->lock, flags);
+ (void) mct_u232_set_modem_ctrl(port->serial, control_state);
+ } else {
+ spin_unlock_irqrestore(&priv->lock, flags);
+ }
+}
+
+
+static void mct_u232_unthrottle (struct usb_serial_port *port)
+{
+ struct mct_u232_private *priv = usb_get_serial_port_data(port);
+ unsigned long flags;
+ unsigned int control_state;
+ struct tty_struct *tty;
+
+ dbg("%s - port %d", __FUNCTION__, port->number);
+
+ tty = port->tty;
+ spin_lock_irqsave(&priv->lock, flags);
+ if ((priv->rx_flags & THROTTLED) && C_CRTSCTS(tty)) {
+ priv->rx_flags &= ~THROTTLED;
+ priv->control_state |= TIOCM_RTS;
+ control_state = priv->control_state;
+ spin_unlock_irqrestore(&priv->lock, flags);
+ (void) mct_u232_set_modem_ctrl(port->serial, control_state);
+ } else {
+ spin_unlock_irqrestore(&priv->lock, flags);
+ }
+}
static int __init mct_u232_init (void)
{
diff --git a/drivers/usb/serial/mct_u232.h b/drivers/usb/serial/mct_u232.h
index 73dd0d9..a61bac8 100644
--- a/drivers/usb/serial/mct_u232.h
+++ b/drivers/usb/serial/mct_u232.h
@@ -63,14 +63,15 @@
#define MCT_U232_SET_UNKNOWN1_REQUEST 11 /* Unknown functionality */
#define MCT_U232_SET_UNKNOWN1_SIZE 1
-/* This USB device request code is not well understood. It is transmitted by
- the MCT-supplied Windows driver whenever the baud rate changes.
+/* This USB device request code appears to control whether CTS is required
+ during transmission.
- Without this USB device request, the USB/RS-232 adapter will not write to
- RS-232 devices which do not assert the 'CTS' signal.
+ Sending a zero byte allows data transmission to a device which is not
+ asserting CTS. Sending a '1' byte will cause transmission to be deferred
+ until the device asserts CTS.
*/
-#define MCT_U232_SET_UNKNOWN2_REQUEST 12 /* Unknown functionality */
-#define MCT_U232_SET_UNKNOWN2_SIZE 1
+#define MCT_U232_SET_CTS_REQUEST 12
+#define MCT_U232_SET_CTS_SIZE 1
/*
* Baud rate (divisor)
@@ -439,7 +440,7 @@
* which says "U232-P9" ;-)
*
* The circuit board inside the adaptor contains a Philips PDIUSBD12
- * USB endpoint chip and a Phillips P87C52UBAA microcontroller with
+ * USB endpoint chip and a Philips P87C52UBAA microcontroller with
* embedded UART. Exhaustive documentation for these is available at:
*
* http://www.semiconductors.philips.com/pip/p87c52ubaa
