sysclk-lwla: Add support for external trigger input.

Implement the configuration setting TRIGGER_SOURCE with the
choices CH (logic channels) and TRG (external trigger input).
Also implement the TRIGGER_SLOPE setting for selecting the
edge to trigger on (rising or falling).

hardware/sysclk-lwla/api.c

@@ -34,6 +34,8 @@ static const int32_t hwcaps[] = {
 	SR_CONF_SAMPLERATE,
 	SR_CONF_EXTERNAL_CLOCK,
 	SR_CONF_TRIGGER_TYPE,
+	SR_CONF_TRIGGER_SOURCE,
+	SR_CONF_TRIGGER_SLOPE,
 	SR_CONF_LIMIT_MSEC,
 	SR_CONF_LIMIT_SAMPLES,
 };
@@ -51,6 +53,16 @@ static const uint64_t samplerates[] = {
 	SR_HZ(500),  SR_HZ(200),  SR_HZ(100),
 };
 
+/* Names assigned to available trigger sources.  Indices must match
+ * trigger_source enum values.
+ */
+static const char *const trigger_source_names[] = { "CH", "TRG" };
+
+/* Names assigned to available trigger slope choices.  Indices must
+ * match trigger_slope enum values.
+ */
+static const char *const trigger_slope_names[] = { "r", "f" };
+
 SR_PRIV struct sr_dev_driver sysclk_lwla_driver_info;
 static struct sr_dev_driver *const di = &sysclk_lwla_driver_info;
 
@@ -259,6 +271,7 @@ static int config_get(int key, GVariant **data, const struct sr_dev_inst *sdi,
 		      const struct sr_probe_group *probe_group)
 {
 	struct dev_context *devc;
+	size_t idx;
 
 	(void)probe_group;
 
@@ -281,6 +294,18 @@ static int config_get(int key, GVariant **data, const struct sr_dev_inst *sdi,
 		*data = g_variant_new_boolean(devc->selected_clock_source
 						>= CLOCK_SOURCE_EXT_RISE);
 		break;
+	case SR_CONF_TRIGGER_SOURCE:
+		idx = devc->cfg_trigger_source;
+		if (idx >= G_N_ELEMENTS(trigger_source_names))
+			return SR_ERR_BUG;
+		*data = g_variant_new_string(trigger_source_names[idx]);
+		break;
+	case SR_CONF_TRIGGER_SLOPE:
+		idx = devc->cfg_trigger_slope;
+		if (idx >= G_N_ELEMENTS(trigger_slope_names))
+			return SR_ERR_BUG;
+		*data = g_variant_new_string(trigger_slope_names[idx]);
+		break;
 	default:
 		return SR_ERR_NA;
 	}
@@ -288,11 +313,32 @@ static int config_get(int key, GVariant **data, const struct sr_dev_inst *sdi,
 	return SR_OK;
 }
 
+/* Helper for mapping a string-typed configuration value to an index
+ * within a table of possible values.
+ */
+static int lookup_index(GVariant *value, const char *const *table, int len)
+{
+	const char *entry;
+	int i;
+
+	entry = g_variant_get_string(value, NULL);
+	if (!entry)
+		return -1;
+
+	/* Linear search is fine for very small tables. */
+	for (i = 0; i < len; ++i) {
+		if (strcmp(entry, table[i]) == 0)
+			return i;
+	}
+	return -1;
+}
+
 static int config_set(int key, GVariant *data, const struct sr_dev_inst *sdi,
 		      const struct sr_probe_group *probe_group)
 {
 	uint64_t value;
 	struct dev_context *devc;
+	int idx;
 
 	(void)probe_group;
 
@@ -330,6 +376,20 @@ static int config_set(int key, GVariant *data, const struct sr_dev_inst *sdi,
 			devc->selected_clock_source = CLOCK_SOURCE_INT;
 		}
 		break;
+	case SR_CONF_TRIGGER_SOURCE:
+		idx = lookup_index(data, trigger_source_names,
+				   G_N_ELEMENTS(trigger_source_names));
+		if (idx < 0)
+			return SR_ERR_ARG;
+		devc->cfg_trigger_source = idx;
+		break;
+	case SR_CONF_TRIGGER_SLOPE:
+		idx = lookup_index(data, trigger_slope_names,
+				   G_N_ELEMENTS(trigger_slope_names));
+		if (idx < 0)
+			return SR_ERR_ARG;
+		devc->cfg_trigger_slope = idx;
+		break;
 	default:
 		return SR_ERR_NA;
 	}
@@ -441,6 +501,14 @@ static int config_list(int key, GVariant **data, const struct sr_dev_inst *sdi,
 	case SR_CONF_TRIGGER_TYPE:
 		*data = g_variant_new_string(TRIGGER_TYPES);
 		break;
+	case SR_CONF_TRIGGER_SOURCE:
+		*data = g_variant_new_strv(trigger_source_names,
+					   G_N_ELEMENTS(trigger_source_names));
+		break;
+	case SR_CONF_TRIGGER_SLOPE:
+		*data = g_variant_new_strv(trigger_slope_names,
+					   G_N_ELEMENTS(trigger_slope_names));
+		break;
 	default:
 		return SR_ERR_NA;
 	}

hardware/sysclk-lwla/protocol.c

@@ -63,6 +63,7 @@ static int capture_setup(const struct sr_dev_inst *sdi)
 	struct dev_context *devc;
 	struct acquisition_state *acq;
 	uint64_t divider_count;
+	uint64_t trigger_mask;
 	uint64_t memory_limit;
 	uint16_t command[3 + 10*4];
 
@@ -102,10 +103,18 @@ static int capture_setup(const struct sr_dev_inst *sdi)
 	command[17] = LWLA_WORD_2(devc->trigger_edge_mask);
 	command[18] = LWLA_WORD_3(devc->trigger_edge_mask);
 
-	command[19] = LWLA_WORD_0(devc->trigger_mask);
-	command[20] = LWLA_WORD_1(devc->trigger_mask);
-	command[21] = LWLA_WORD_2(devc->trigger_mask);
-	command[22] = LWLA_WORD_3(devc->trigger_mask);
+	trigger_mask = devc->trigger_mask;
+	/* Set bits to select external TRG input edge. */
+	if (devc->cfg_trigger_source == TRIGGER_EXT_TRG)
+		switch (devc->cfg_trigger_slope) {
+		case SLOPE_POSITIVE: trigger_mask |= (uint64_t)1 << 35; break; 
+		case SLOPE_NEGATIVE: trigger_mask |= (uint64_t)1 << 34; break; 
+		}
+
+	command[19] = LWLA_WORD_0(trigger_mask);
+	command[20] = LWLA_WORD_1(trigger_mask);
+	command[21] = LWLA_WORD_2(trigger_mask);
+	command[22] = LWLA_WORD_3(trigger_mask);
 
 	/* Set the capture memory full threshold. This is slightly less
 	 * than the actual maximum, most likely in order to compensate for

hardware/sysclk-lwla/protocol.h

@@ -110,6 +110,20 @@ enum clock_source {
 	CLOCK_SOURCE_EXT_FALL,
 };
 
+/** Available trigger sources.
+ */
+enum trigger_source {
+	TRIGGER_CHANNELS = 0,
+	TRIGGER_EXT_TRG,
+};
+
+/** Available edge choices for the external trigger.
+ */
+enum trigger_slope {
+	SLOPE_POSITIVE = 0,
+	SLOPE_NEGATIVE,
+};
+
 /** LWLA device states.
  */
 enum device_state {
@@ -214,6 +228,11 @@ struct dev_context {
 	/** The clock source selected by the user. */
 	enum clock_source selected_clock_source;
 
+	/** Trigger source configuration setting. */
+	enum trigger_source cfg_trigger_source;
+	/** Trigger slope configuration setting. */
+	enum trigger_slope cfg_trigger_slope;
+
 	/* Indicates that stopping the acquisition is currently in progress. */
 	gboolean stopping_in_progress;