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, 6 insertions, 4 deletions

diff --git a/drivers/staging/speakup/serialio.c b/drivers/staging/speakup/serialio.c
index ba060d0ceca2..5f96b5ba7acb 100644
--- a/drivers/staging/speakup/serialio.c
+++ b/drivers/staging/speakup/serialio.c
@@ -28,11 +28,15 @@ static int timeouts;
 static int spk_serial_out(struct spk_synth *in_synth, const char ch);
 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);
 
 struct spk_io_ops spk_serial_io_ops = {
 	.synth_out = spk_serial_out,
 	.send_xchar = spk_serial_send_xchar,
 	.tiocmset = spk_serial_tiocmset,
+	.synth_in = spk_serial_in,
+	.synth_in_nowait = spk_serial_in_nowait,
 };
 EXPORT_SYMBOL_GPL(spk_serial_io_ops);
 
@@ -240,7 +244,7 @@ int spk_wait_for_xmitr(struct spk_synth *in_synth)
 	return 1;
 }
 
-unsigned char spk_serial_in(void)
+static unsigned char spk_serial_in(void)
 {
 	int tmout = SPK_SERIAL_TIMEOUT;
 
@@ -253,9 +257,8 @@ unsigned char spk_serial_in(void)
 	}
 	return inb_p(speakup_info.port_tts + UART_RX);
 }
-EXPORT_SYMBOL_GPL(spk_serial_in);
 
-unsigned char spk_serial_in_nowait(void)
+static unsigned char spk_serial_in_nowait(void)
 {
 	unsigned char lsr;
 
@@ -264,7 +267,6 @@ unsigned char spk_serial_in_nowait(void)
 		return 0;
 	return inb_p(speakup_info.port_tts + UART_RX);
 }
-EXPORT_SYMBOL_GPL(spk_serial_in_nowait);
 
 static int spk_serial_out(struct spk_synth *in_synth, const char ch)
 {