staging: speakup: flush tty buffers and ensure hardware flow control

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.

It also tries to ensure that hardware flow control is enabled, by
setting CRTSCTS using tty's termios.

Reported-by: John Covici <covici@ccs.covici.com>
Signed-off-by: Okash Khawaja <okash.khawaja@gmail.com>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/speakup/serialio.c b/drivers/staging/speakup/serialio.c
index 5f96b5b..9693732 100644 (file)
--- a/drivers/staging/speakup/serialio.c
+++ b/drivers/staging/speakup/serialio.c
@@ -30,6 +30,7 @@ static void spk_serial_send_xchar(char ch);
 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 @@ struct spk_io_ops spk_serial_io_ops = {
        .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 @@ static unsigned char spk_serial_in_nowait(void)
        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)) {

diff --git a/drivers/staging/speakup/speakup_audptr.c b/drivers/staging/speakup/speakup_audptr.c
index aa6c592..1ca4760 100644 (file)
--- a/drivers/staging/speakup/speakup_audptr.c
+++ b/drivers/staging/speakup/speakup_audptr.c
@@ -127,6 +127,7 @@ static struct spk_synth synth_audptr = {
 
 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);
 }

diff --git a/drivers/staging/speakup/speakup_decext.c b/drivers/staging/speakup/speakup_decext.c
index b70bba8..bf44ac9 100644 (file)
--- a/drivers/staging/speakup/speakup_decext.c
+++ b/drivers/staging/speakup/speakup_decext.c
@@ -221,6 +221,7 @@ static void do_catch_up(struct spk_synth *synth)
 static void synth_flush(struct spk_synth *synth)
 {
        in_escape = 0;
+       synth->io_ops->flush_buffer();
        synth->synth_immediate(synth, "\033P;10z\033\\");
 }
 

diff --git a/drivers/staging/speakup/speakup_dectlk.c b/drivers/staging/speakup/speakup_dectlk.c
index ec968dd..ccb3bdf 100644 (file)
--- a/drivers/staging/speakup/speakup_dectlk.c
+++ b/drivers/staging/speakup/speakup_dectlk.c
@@ -293,6 +293,7 @@ static void synth_flush(struct spk_synth *synth)
                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);
 }
 

diff --git a/drivers/staging/speakup/speakup_spkout.c b/drivers/staging/speakup/speakup_spkout.c
index fa1a40b..086d534 100644 (file)
--- a/drivers/staging/speakup/speakup_spkout.c
+++ b/drivers/staging/speakup/speakup_spkout.c
@@ -125,6 +125,7 @@ static struct spk_synth synth_spkout = {
 
 static void synth_flush(struct spk_synth *synth)
 {
+       synth->io_ops->flush_buffer();
        synth->io_ops->send_xchar(SYNTH_CLEAR);
 }
 

diff --git a/drivers/staging/speakup/spk_ttyio.c b/drivers/staging/speakup/spk_ttyio.c
index 61c01bf..6e0f042 100644 (file)
--- a/drivers/staging/speakup/spk_ttyio.c
+++ b/drivers/staging/speakup/spk_ttyio.c
@@ -85,6 +85,7 @@ static void spk_ttyio_send_xchar(char ch);
 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,
@@ -92,13 +93,22 @@ struct spk_io_ops spk_ttyio_ops = {
        .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);
 
+static inline void get_termios(struct tty_struct *tty, struct ktermios *out_termios)
+{
+       down_read(&tty->termios_rwsem);
+       *out_termios = tty->termios;
+       up_read(&tty->termios_rwsem);
+}
+
 static int spk_ttyio_initialise_ldisc(int ser)
 {
        int ret = 0;
        struct tty_struct *tty;
+       struct ktermios tmp_termios;
 
        ret = tty_register_ldisc(N_SPEAKUP, &spk_ttyio_ldisc_ops);
        if (ret) {
@@ -127,6 +137,20 @@ static int spk_ttyio_initialise_ldisc(int ser)
        }
 
        clear_bit(TTY_HUPPED, &tty->flags);
+       /* ensure hardware flow control is enabled */
+       get_termios(tty, &tmp_termios);
+       if (!(tmp_termios.c_cflag & CRTSCTS)) {
+               tmp_termios.c_cflag |= CRTSCTS;
+               tty_set_termios(tty, &tmp_termios);
+               /*
+                * check c_cflag to see if it's updated as tty_set_termios may not return
+                * error even when no tty bits are changed by the request.
+                */
+               get_termios(tty, &tmp_termios);
+               if (!(tmp_termios.c_cflag & CRTSCTS))
+                       pr_warn("speakup: Failed to set hardware flow control\n");
+       }
+
        tty_unlock(tty);
 
        ret = tty_set_ldisc(tty, N_SPEAKUP);
@@ -201,6 +225,11 @@ static unsigned char spk_ttyio_in_nowait(void)
        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);

diff --git a/drivers/staging/speakup/spk_types.h b/drivers/staging/speakup/spk_types.h
index ad7b948..9e38897 100644 (file)
--- a/drivers/staging/speakup/spk_types.h
+++ b/drivers/staging/speakup/spk_types.h
@@ -154,6 +154,7 @@ struct spk_io_ops {
        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 {

diff --git a/drivers/staging/speakup/synth.c b/drivers/staging/speakup/synth.c
index 9c2aa1b..7035539 100644 (file)
--- a/drivers/staging/speakup/synth.c
+++ b/drivers/staging/speakup/synth.c
@@ -120,6 +120,7 @@ EXPORT_SYMBOL_GPL(spk_do_catch_up);
 
 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);