staging: speakup: flush tty buffers

[Okash Khawaja]

This patch fixes the issue where TTY-migrated synths would take a while
to shut up after hitting numpad enter key. When calling synth_flush, even
though XOFF character is sent as high priority, data buffered in TTY layer
is still sent to the synth. This patch flushes that buffered data when
synth_flush is called.

Reported-by: John Covici <covici at ccs.covici.com>
Signed-off-by: Okash Khawaja <okash.khawaja at gmail.com>

Index: linux-staging/drivers/staging/speakup/serialio.c
===================================================================
--- linux-staging.orig/drivers/staging/speakup/serialio.c
+++ linux-staging/drivers/staging/speakup/serialio.c
@@ -30,6 +30,7 @@
 static void spk_serial_tiocmset(unsigned int set, unsigned int clear);
 static unsigned char spk_serial_in(void);
 static unsigned char spk_serial_in_nowait(void);
+static void spk_serial_flush_buffer(void);
 
 struct spk_io_ops spk_serial_io_ops = {
 	.synth_out = spk_serial_out,
@@ -37,6 +38,7 @@
 	.tiocmset = spk_serial_tiocmset,
 	.synth_in = spk_serial_in,
 	.synth_in_nowait = spk_serial_in_nowait,
+	.flush_buffer = spk_serial_flush_buffer,
 };
 EXPORT_SYMBOL_GPL(spk_serial_io_ops);
 
@@ -268,6 +270,11 @@
 	return inb_p(speakup_info.port_tts + UART_RX);
 }
 
+static void spk_serial_flush_buffer(void)
+{
+	/* TODO: flush the UART 16550 buffer */
+}
+
 static int spk_serial_out(struct spk_synth *in_synth, const char ch)
 {
 	if (in_synth->alive && spk_wait_for_xmitr(in_synth)) {
Index: linux-staging/drivers/staging/speakup/spk_ttyio.c
===================================================================
--- linux-staging.orig/drivers/staging/speakup/spk_ttyio.c
+++ linux-staging/drivers/staging/speakup/spk_ttyio.c
@@ -85,6 +85,7 @@
 static void spk_ttyio_tiocmset(unsigned int set, unsigned int clear);
 static unsigned char spk_ttyio_in(void);
 static unsigned char spk_ttyio_in_nowait(void);
+static void spk_ttyio_flush_buffer(void);
 
 struct spk_io_ops spk_ttyio_ops = {
 	.synth_out = spk_ttyio_out,
@@ -92,6 +93,7 @@
 	.tiocmset = spk_ttyio_tiocmset,
 	.synth_in = spk_ttyio_in,
 	.synth_in_nowait = spk_ttyio_in_nowait,
+	.flush_buffer = spk_ttyio_flush_buffer,
 };
 EXPORT_SYMBOL_GPL(spk_ttyio_ops);
 
@@ -201,6 +203,11 @@
 	return (rv == 0xff) ? 0 : rv;
 }
 
+static void spk_ttyio_flush_buffer(void)
+{
+	speakup_tty->ops->flush_buffer(speakup_tty);
+}
+
 int spk_ttyio_synth_probe(struct spk_synth *synth)
 {
 	int rv = spk_ttyio_initialise_ldisc(synth->ser);
Index: linux-staging/drivers/staging/speakup/spk_types.h
===================================================================
--- linux-staging.orig/drivers/staging/speakup/spk_types.h
+++ linux-staging/drivers/staging/speakup/spk_types.h
@@ -154,6 +154,7 @@
 	void (*tiocmset)(unsigned int set, unsigned int clear);
 	unsigned char (*synth_in)(void);
 	unsigned char (*synth_in_nowait)(void);
+	void (*flush_buffer)(void);
 };
 
 struct spk_synth {
Index: linux-staging/drivers/staging/speakup/speakup_audptr.c
===================================================================
--- linux-staging.orig/drivers/staging/speakup/speakup_audptr.c
+++ linux-staging/drivers/staging/speakup/speakup_audptr.c
@@ -127,6 +127,7 @@
 
 static void synth_flush(struct spk_synth *synth)
 {
+	synth->io_ops->flush_buffer();
 	synth->io_ops->send_xchar(SYNTH_CLEAR);
 	synth->io_ops->synth_out(synth, PROCSPEECH);
 }
Index: linux-staging/drivers/staging/speakup/speakup_decext.c
===================================================================
--- linux-staging.orig/drivers/staging/speakup/speakup_decext.c
+++ linux-staging/drivers/staging/speakup/speakup_decext.c
@@ -221,6 +221,7 @@
 static void synth_flush(struct spk_synth *synth)
 {
 	in_escape = 0;
+	synth->io_ops->flush_buffer();
 	synth->synth_immediate(synth, "\033P;10z\033\\");
 }
 
Index: linux-staging/drivers/staging/speakup/speakup_dectlk.c
===================================================================
--- linux-staging.orig/drivers/staging/speakup/speakup_dectlk.c
+++ linux-staging/drivers/staging/speakup/speakup_dectlk.c
@@ -293,6 +293,7 @@
 		synth->io_ops->synth_out(synth, ']');
 	in_escape = 0;
 	is_flushing = 1;
+	synth->io_ops->flush_buffer();
 	synth->io_ops->synth_out(synth, SYNTH_CLEAR);
 }
 
Index: linux-staging/drivers/staging/speakup/speakup_spkout.c
===================================================================
--- linux-staging.orig/drivers/staging/speakup/speakup_spkout.c
+++ linux-staging/drivers/staging/speakup/speakup_spkout.c
@@ -125,6 +125,7 @@
 
 static void synth_flush(struct spk_synth *synth)
 {
+	synth->io_ops->flush_buffer();
 	synth->io_ops->send_xchar(SYNTH_CLEAR);
 }
 
Index: linux-staging/drivers/staging/speakup/synth.c
===================================================================
--- linux-staging.orig/drivers/staging/speakup/synth.c
+++ linux-staging/drivers/staging/speakup/synth.c
@@ -120,6 +120,7 @@
 
 void spk_synth_flush(struct spk_synth *synth)
 {
+	synth->io_ops->flush_buffer();
 	synth->io_ops->synth_out(synth, synth->clear);
 }
 EXPORT_SYMBOL_GPL(spk_synth_flush);