USB: serial: cp210x.c: add mark/space parity

[Roland Koebler <r.koebler@xxxxxxxx>]

Hi,

nearly all usb-serial-converters support mark/space parity, but
unfortunately, most drivers in the Linux kernel ignore this.

So, this patch adds mark and space parity support to cp210x.c
It should work with both 2.6.x and 3.x kernels.

regards
Roland

--- cp210x.orig.c	2011-11-09 14:07:29.000000000 +0100
+++ cp210x.c	2011-11-09 14:17:40.000000000 +0100
@@ -9,7 +9,8 @@
  *
  * Support to set flow control line levels using TIOCMGET and TIOCMSET
  * thanks to Karl Hiramoto karl@xxxxxxxxxxxx. RTSCTS hardware flow
- * control thanks to Munir Nassar nassarmu@xxxxxxxxxxxxx
+ * control thanks to Munir Nassar nassarmu@xxxxxxxxxxxxx. Mark/space
+ * parity thanks to Roland Koebler rk@xxxxxxxxxxx.
  *
  */
 
@@ -520,18 +521,13 @@
 		cflag |= PARENB;
 		break;
 	case BITS_PARITY_MARK:
-		dbg("%s - parity = MARK (not supported, disabling parity)",
-				__func__);
-		cflag &= ~PARENB;
-		bits &= ~BITS_PARITY_MASK;
-		cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2);
+		dbg("%s - parity = MARK", __func__);
+		cflag |= (PARENB|PARODD|CMSPAR);
 		break;
 	case BITS_PARITY_SPACE:
-		dbg("%s - parity = SPACE (not supported, disabling parity)",
-				__func__);
-		cflag &= ~PARENB;
-		bits &= ~BITS_PARITY_MASK;
-		cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2);
+		dbg("%s - parity = SPACE", __func__);
+		cflag &= ~PARODD;
+		cflag |= (PARENB|CMSPAR);
 		break;
 	default:
 		dbg("%s - Unknown parity mode, disabling parity", __func__);
@@ -588,7 +584,6 @@
 	if (!tty)
 		return;
 
-	tty->termios->c_cflag &= ~CMSPAR;
 	cflag = tty->termios->c_cflag;
 	old_cflag = old_termios->c_cflag;
 	baud = cp210x_quantise_baudrate(tty_get_baud_rate(tty));
@@ -643,16 +638,27 @@
 					"not supported by device\n");
 	}
 
-	if ((cflag & (PARENB|PARODD)) != (old_cflag & (PARENB|PARODD))) {
+        if ((cflag     & (PARENB|PARODD|CMSPAR)) !=
+            (old_cflag & (PARENB|PARODD|CMSPAR))) {
 		cp210x_get_config(port, CP210X_GET_LINE_CTL, &bits, 2);
 		bits &= ~BITS_PARITY_MASK;
 		if (cflag & PARENB) {
-			if (cflag & PARODD) {
-				bits |= BITS_PARITY_ODD;
-				dbg("%s - parity = ODD", __func__);
+			if (cflag & CMSPAR) {
+			    if (cflag & PARODD) {
+				    bits |= BITS_PARITY_MARK;
+				    dbg("%s - parity = MARK", __func__);
+			    } else {
+				    bits |= BITS_PARITY_SPACE;
+				    dbg("%s - parity = SPACE", __func__);
+			    }
 			} else {
-				bits |= BITS_PARITY_EVEN;
-				dbg("%s - parity = EVEN", __func__);
+			    if (cflag & PARODD) {
+				    bits |= BITS_PARITY_ODD;
+				    dbg("%s - parity = ODD", __func__);
+			    } else {
+				    bits |= BITS_PARITY_EVEN;
+				    dbg("%s - parity = EVEN", __func__);
+			    }
 			}
 		}
 		if (cp210x_set_config(port, CP210X_SET_LINE_CTL, &bits, 2))