speakup: Make dectlk flush timeout configurable

In case the serial port or cable got faulty, we may not be getting
acknowledgements any more. The driver then currently waits for 4s to
avoid jamming the device. This makes this delay configurable.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Link: https://lore.kernel.org/r/20210128180116.1848120-3-samuel.thibault@ens-lyon.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/ABI/stable/sysfs-driver-speakup

@@ -312,6 +312,13 @@ Contact:	speakup@linux-speakup.org
 Description:	Gets or sets the frequency of the speech synthesizer. Range is
 		0-9.
 
+What:		/sys/accessibility/speakup/<synth-name>/flush_time
+KernelVersion:	5.12
+Contact:	speakup@linux-speakup.org
+Description:	Gets or sets the timeout to wait for the synthesizer flush to
+		complete. This can be used when the cable gets faulty and flush
+		notifications are getting lost.
+
 What:		/sys/accessibility/speakup/<synth-name>/full_time
 KernelVersion:	2.6
 Contact:	speakup@linux-speakup.org

drivers/accessibility/speakup/speakup_dectlk.c

@@ -78,6 +78,8 @@ static struct kobj_attribute direct_attribute =
 	__ATTR(direct, 0644, spk_var_show, spk_var_store);
 static struct kobj_attribute full_time_attribute =
 	__ATTR(full_time, 0644, spk_var_show, spk_var_store);
+static struct kobj_attribute flush_time_attribute =
+	__ATTR(flush_time, 0644, spk_var_show, spk_var_store);
 static struct kobj_attribute jiffy_delta_attribute =
 	__ATTR(jiffy_delta, 0644, spk_var_show, spk_var_store);
 static struct kobj_attribute trigger_time_attribute =
@@ -99,6 +101,7 @@ static struct attribute *synth_attrs[] = {
 	&delay_time_attribute.attr,
 	&direct_attribute.attr,
 	&full_time_attribute.attr,
+	&flush_time_attribute.attr,
 	&jiffy_delta_attribute.attr,
 	&trigger_time_attribute.attr,
 	NULL,	/* need to NULL terminate the list of attributes */
@@ -118,6 +121,7 @@ static struct spk_synth synth_dectlk = {
 	.trigger = 50,
 	.jiffies = 50,
 	.full = 40000,
+	.flush_time = 4000,
 	.dev_name = SYNTH_DEFAULT_DEV,
 	.startup = SYNTH_START,
 	.checkval = SYNTH_CHECK,
@@ -200,18 +204,23 @@ static void do_catch_up(struct spk_synth *synth)
 	static u_char last = '\0';
 	unsigned long flags;
 	unsigned long jiff_max;
-	unsigned long timeout = msecs_to_jiffies(4000);
+	unsigned long timeout;
 	DEFINE_WAIT(wait);
 	struct var_t *jiffy_delta;
 	struct var_t *delay_time;
+	struct var_t *flush_time;
 	int jiffy_delta_val;
 	int delay_time_val;
+	int timeout_val;
 
 	jiffy_delta = spk_get_var(JIFFY);
 	delay_time = spk_get_var(DELAY);
+	flush_time = spk_get_var(FLUSH);
 	spin_lock_irqsave(&speakup_info.spinlock, flags);
 	jiffy_delta_val = jiffy_delta->u.n.value;
+	timeout_val = flush_time->u.n.value;
 	spin_unlock_irqrestore(&speakup_info.spinlock, flags);
+	timeout = msecs_to_jiffies(timeout_val);
 	jiff_max = jiffies + jiffy_delta_val;
 
 	while (!kthread_should_stop()) {

drivers/accessibility/speakup/spk_types.h

@@ -48,7 +48,7 @@ enum var_id_t {
 	ATTRIB_BLEEP, BLEEPS,
 	RATE, PITCH, VOL, TONE, PUNCT, VOICE, FREQUENCY, LANG,
 	DIRECT, PAUSE,
-	CAPS_START, CAPS_STOP, CHARTAB, INFLECTION,
+	CAPS_START, CAPS_STOP, CHARTAB, INFLECTION, FLUSH,
 	MAXVARS
 };
 
@@ -178,6 +178,7 @@ struct spk_synth {
 	int trigger;
 	int jiffies;
 	int full;
+	int flush_time;
 	int ser;
 	char *dev_name;
 	short flags;

drivers/accessibility/speakup/synth.c

@@ -348,6 +348,7 @@ struct var_t synth_time_vars[] = {
 	{ TRIGGER, .u.n = {NULL, 20, 10, 2000, 0, 0, NULL } },
 	{ JIFFY, .u.n = {NULL, 50, 20, 200, 0, 0, NULL } },
 	{ FULL, .u.n = {NULL, 400, 200, 60000, 0, 0, NULL } },
+	{ FLUSH, .u.n = {NULL, 4000, 100, 4000, 0, 0, NULL } },
 	V_LAST_VAR
 };
 
@@ -408,6 +409,8 @@ static int do_synth_init(struct spk_synth *in_synth)
 		synth_time_vars[2].u.n.default_val = synth->jiffies;
 	synth_time_vars[3].u.n.value =
 		synth_time_vars[3].u.n.default_val = synth->full;
+	synth_time_vars[4].u.n.value =
+		synth_time_vars[4].u.n.default_val = synth->flush_time;
 	synth_printf("%s", synth->init);
 	for (var = synth->vars;
 		(var->var_id >= 0) && (var->var_id < MAXVARS); var++)

drivers/accessibility/speakup/varhandlers.c

@@ -23,6 +23,7 @@ static struct st_var_header var_headers[] = {
 	{ "trigger_time", TRIGGER, VAR_TIME, NULL, NULL },
 	{ "jiffy_delta", JIFFY, VAR_TIME, NULL, NULL },
 	{ "full_time", FULL, VAR_TIME, NULL, NULL },
+	{ "flush_time", FLUSH, VAR_TIME, NULL, NULL },
 	{ "spell_delay", SPELL_DELAY, VAR_NUM, &spk_spell_delay, NULL },
 	{ "bleeps", BLEEPS, VAR_NUM, &spk_bleeps, NULL },
 	{ "attrib_bleep", ATTRIB_BLEEP, VAR_NUM, &spk_attrib_bleep, NULL },