synclink_gt: improve and simplify write method

Improve write method by allowing multiple HDLC frames to be loaded into tx
DMA buffer ring for continuous frame transmission.  This simplifies the
transmit code by using the common procedures for all serial protocols.
Signed-off-by: NPaul Fulghum <paulkf@microgate.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAlan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/char/synclink_gt.c

@@ -849,6 +849,7 @@ static int write(struct tty_struct *tty,
 	int ret = 0;
 	struct slgt_info *info = tty->driver_data;
 	unsigned long flags;
+	unsigned int bufs_needed;
 
 	if (sanity_check(info, tty->name, "write"))
 		goto cleanup;
@@ -865,25 +866,16 @@ static int write(struct tty_struct *tty,
 	if (!count)
 		goto cleanup;
 
-	if (info->params.mode == MGSL_MODE_RAW ||
-	    info->params.mode == MGSL_MODE_MONOSYNC ||
-	    info->params.mode == MGSL_MODE_BISYNC) {
-		unsigned int bufs_needed = (count/DMABUFSIZE);
-		unsigned int bufs_free = free_tbuf_count(info);
-		if (count % DMABUFSIZE)
-			++bufs_needed;
-		if (bufs_needed > bufs_free)
-			goto cleanup;
-	} else {
-		if (info->tx_active)
-			goto cleanup;
-		if (info->tx_count) {
-			/* send accumulated data from send_char() calls */
-			/* as frame and wait before accepting more data. */
-			tx_load(info, info->tx_buf, info->tx_count);
-			goto start;
-		}
+	if (!info->tx_active && info->tx_count) {
+		/* send accumulated data from send_char() */
+		tx_load(info, info->tx_buf, info->tx_count);
+		goto start;
 	}
+	bufs_needed = (count/DMABUFSIZE);
+	if (count % DMABUFSIZE)
+		++bufs_needed;
+	if (bufs_needed > free_tbuf_count(info))
+		goto cleanup;
 
 	ret = info->tx_count = count;
 	tx_load(info, buf, count);
@@ -3935,15 +3927,7 @@ static void tdma_start(struct slgt_info *info)
 
 	/* set 1st descriptor address */
 	wr_reg32(info, TDDAR, info->tbufs[info->tbuf_start].pdesc);
-	switch(info->params.mode) {
-	case MGSL_MODE_RAW:
-	case MGSL_MODE_MONOSYNC:
-	case MGSL_MODE_BISYNC:
-		wr_reg32(info, TDCSR, BIT2 + BIT0); /* IRQ + DMA enable */
-		break;
-	default:
-		wr_reg32(info, TDCSR, BIT0); /* DMA enable */
-	}
+	wr_reg32(info, TDCSR, BIT2 + BIT0); /* IRQ + DMA enable */
 }
 
 static void tx_stop(struct slgt_info *info)