speakup_dummy: log about characters received by the dummy driver

The dummy speakup driver is used to check that speakup is working
properly, without the need for actually owning the hardware. Some
drivers require receiving characters, so we need a way to check that
this is working properly.
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Link: https://lore.kernel.org/r/20201101183913.yg35cbqpn2ba6cew@functionSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/accessibility/speakup/speakup_dummy.c

@@ -80,6 +80,11 @@ static struct attribute *synth_attrs[] = {
 	NULL,	/* need to NULL terminate the list of attributes */
 };
 
+static void read_buff_add(u_char c)
+{
+	pr_info("speakup_dummy: got character %02x\n", c);
+}
+
 static struct spk_synth synth_dummy = {
 	.name = "dummy",
 	.version = DRV_VERSION,
@@ -103,7 +108,7 @@ static struct spk_synth synth_dummy = {
 	.flush = spk_synth_flush,
 	.is_alive = spk_synth_is_alive_restart,
 	.synth_adjust = NULL,
-	.read_buff_add = NULL,
+	.read_buff_add = read_buff_add,
 	.get_index = NULL,
 	.indexing = {
 		.command = NULL,