staging: speakup: make input functionality swappable

This moves functions which take input from external synth, into struct
spk_io_ops. The calling code then uses serial implementation of those methods
through spk_io_ops. That way we can add a parallel TTY-based implementation and
simply replace serial with TTY. That is what the next patch in this series does.

speakup_decext.c has get_last_char function which reads the most recent
available character from the synth. This patch changes that by defining
read_buff_add callback method of spk_syth and letting that update the last_char
global character read from the synth. read_buff_add is called from ISR, so
there is a possibility for last_char to be stale. Therefore it is marked as
volatile. It also pulls a repeated get_index implementation into synth.c, to
be used as a utility function.

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>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/staging/speakup/speakup_audptr.c b/drivers/staging/speakup/speakup_audptr.c
index 6880352a7b74..800677bc1dad 100644
--- a/drivers/staging/speakup/speakup_audptr.c
+++ b/drivers/staging/speakup/speakup_audptr.c
@@ -138,11 +138,11 @@ static void synth_version(struct spk_synth *synth)
 	char synth_id[40] = "";
 
 	synth->synth_immediate(synth, "\x05[Q]");
-	synth_id[test] = spk_serial_in();
+	synth_id[test] = synth->io_ops->synth_in();
 	if (synth_id[test] == 'A') {
 		do {
 			/* read version string from synth */
-			synth_id[++test] = spk_serial_in();
+			synth_id[++test] = synth->io_ops->synth_in();
 		} while (synth_id[test] != '\n' && test < 32);
 		synth_id[++test] = 0x00;
 	}