advertising: Expose SupportedCapabilities for advertising

To help our advertising clients understand the device capabilities, this
patch adds a SupportedCapabilities dbus endpoint for the advertising
manager. The primary reason behind this is to provide the valid LE tx
power range the controller supports (populated if controller supports
BT5), so a client can know the valid power range before requesting a tx
power for their advertisement.

I also thought it would be useful to indicate the max advertising data
length and scan response length in this endpoint, since some clients
will find it useful to set their advertising data (currently
experimental feature) or scan response data (possible future feature)
directly.

This patch has been tested on Hatch (BT5 support) and Kukui (No BT5
support) chromebooks to verify that the dbus endpoint contains the
correct data.

1 files changed, 35 insertions, 0 deletions

diff --git a/src/advertising.c b/src/advertising.c
index f12534776..4f5123fa1 100644
--- a/src/advertising.c
+++ b/src/advertising.c
@@ -1640,12 +1640,47 @@ static gboolean get_supported_secondary(const GDBusPropertyTable *property,
 	return TRUE;
 }
 
+static gboolean get_supported_cap(const GDBusPropertyTable *property,
+					DBusMessageIter *iter, void *data)
+{
+	struct btd_adv_manager *manager = data;
+	DBusMessageIter dict;
+	int16_t min_tx_power = manager->min_tx_power;
+	int16_t max_tx_power = manager->max_tx_power;
+
+	dbus_message_iter_open_container(iter, DBUS_TYPE_ARRAY,
+					DBUS_DICT_ENTRY_BEGIN_CHAR_AS_STRING
+					DBUS_TYPE_STRING_AS_STRING
+					DBUS_TYPE_VARIANT_AS_STRING
+					DBUS_DICT_ENTRY_END_CHAR_AS_STRING,
+					&dict);
+
+	if (min_tx_power != ADV_TX_POWER_NO_PREFERENCE)
+		dict_append_entry(&dict, "MinTxPower", DBUS_TYPE_INT16,
+				&min_tx_power);
+
+	if (max_tx_power != ADV_TX_POWER_NO_PREFERENCE)
+		dict_append_entry(&dict, "MaxTxPower", DBUS_TYPE_INT16,
+				&max_tx_power);
+
+	dict_append_entry(&dict, "MaxAdvLen", DBUS_TYPE_BYTE,
+			&manager->max_adv_len);
+	dict_append_entry(&dict, "MaxScnRspLen", DBUS_TYPE_BYTE,
+			&manager->max_scan_rsp_len);
+
+	dbus_message_iter_close_container(iter, &dict);
+
+	return TRUE;
+}
+
 static const GDBusPropertyTable properties[] = {
 	{ "ActiveInstances", "y", get_active_instances, NULL, NULL },
 	{ "SupportedInstances", "y", get_instances, NULL, NULL },
 	{ "SupportedIncludes", "as", get_supported_includes, NULL, NULL },
 	{ "SupportedSecondaryChannels", "as", get_supported_secondary, NULL,
 							secondary_exits },
+	{ "SupportedCapabilities", "a{sv}", get_supported_cap, NULL, NULL,
+					G_DBUS_PROPERTY_FLAG_EXPERIMENTAL},
 	{ }
 };