Bluetooth: controller: Add read antenna information HCI command

Add partial implementation for handling Bluetooth 5.1 Direction
Finding HCI command HCI_LE_Read_Antenna_Information to controller
Upper Link layer.

Signed-off-by: Piotr Pryga <piotr.pryga@nordicsemi.no>

subsys/bluetooth/controller/CMakeLists.txt

@@ -100,6 +100,11 @@ if(CONFIG_BT_LL_SW_SPLIT)
       ll_sw/lll_chan.c
       )
   endif()
+  if(CONFIG_BT_CTLR_DF)
+    zephyr_library_sources(
+      ll_sw/ull_df.c
+      )
+  endif()
   zephyr_library_sources_ifdef(
     CONFIG_BT_CTLR_FILTER
     ll_sw/ull_filter.c

subsys/bluetooth/controller/Kconfig

@@ -561,6 +561,11 @@ config BT_CTLR_ASSERT_HANDLER
 	  and will be invoked whenever the controller code encounters
 	  an unrecoverable error.
 
+config BT_CTLR_DF
+	bool "LE Direction Finding Support [EXPERIMENTAL]" if BT_LL_SW_SPLIT
+	help
+	  Enable support for Bluetooth 5.1 Direction Finding
+
 endif # BT_CTLR
 
 config BT_CTLR_DEBUG_PINS_CPUAPP

subsys/bluetooth/controller/hci/hci.c

@@ -2063,6 +2063,28 @@ static void le_read_tx_power(struct net_buf *buf, struct net_buf **evt)
 	ll_tx_pwr_get(&rp->min_tx_power, &rp->max_tx_power);
 }
 
+#if IS_ENABLED(CONFIG_BT_CTLR_DF)
+static void le_df_read_ant_inf(struct net_buf *buf, struct net_buf **evt)
+{
+	struct bt_hci_rp_le_read_ant_info *rp;
+	uint8_t max_switch_pattern_len;
+	uint8_t switch_sample_rates;
+	uint8_t max_cte_len;
+	uint8_t num_ant;
+
+	ll_df_read_ant_inf(&switch_sample_rates, &num_ant,
+			   &max_switch_pattern_len, &max_cte_len);
+
+	rp = hci_cmd_complete(evt, sizeof(*rp));
+
+	rp->max_switch_pattern_len = max_switch_pattern_len;
+	rp->switch_sample_rates = switch_sample_rates;
+	rp->max_cte_len = max_cte_len;
+	rp->num_ant = num_ant;
+	rp->status = 0x00;
+}
+#endif /* CONFIG_BT_CTLR_DF */
+
 #if defined(CONFIG_BT_CTLR_DTM_HCI)
 static void le_rx_test(struct net_buf *buf, struct net_buf **evt)
 {
@@ -3059,6 +3081,12 @@ static int controller_cmd_handle(uint16_t  ocf, struct net_buf *cmd,
 		le_read_tx_power(cmd, evt);
 		break;
 
+#if defined(CONFIG_BT_CTLR_DF)
+	case BT_OCF(BT_HCI_OP_LE_READ_ANT_INFO):
+		le_df_read_ant_inf(cmd, evt);
+		break;
+#endif /* CONFIG_BT_CTLR_DF */
+
 #if defined(CONFIG_BT_CTLR_DTM_HCI)
 	case BT_OCF(BT_HCI_OP_LE_RX_TEST):
 		le_rx_test(cmd, evt);

subsys/bluetooth/controller/include/ll.h

@@ -258,3 +258,11 @@ void ll_rx_mem_release(void **node_rx);
 void ll_timeslice_ticker_id_get(uint8_t * const instance_index, uint8_t * const user_id);
 void ll_radio_state_abort(void);
 uint32_t ll_radio_state_is_idle(void);
+
+/* Direction Finding */
+
+/* Provides information about antennae switching and sampling settings */
+void ll_df_read_ant_inf(uint8_t *switch_sample_rates,
+			uint8_t *num_ant,
+			uint8_t *max_switch_pattern_len,
+			uint8_t *max_cte_len);

subsys/bluetooth/controller/ll_sw/ull_df.c

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2018-2020 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <sys/util.h>
+#include "hal/debug.h"
+#include "ull_df.h"
+
+#define BT_DBG_ENABLED IS_ENABLED(CONFIG_BT_DEBUG_HCI_DRIVER)
+#define LOG_MODULE_NAME bt_ctlr_ull_df
+#include "common/log.h"
+
+/* @brief Function provides information about Direction Finding
+ * antennae switching and sampling related settings.
+ *
+ * @param[out]switch_sample_rates       Pointer to store available antennae
+ *                                      switch-sampling configurations.
+ * @param[out]num_ant                   Pointer to store number of available
+ *                                      antennae.
+ * @param[out]max_switch_pattern_len    Pointer to store maximum number of
+ *                                      antennae switch patterns.
+ * @param[out]max_cte_len               Pointer to store maximum length of CTE
+ *                                      in [8us] units.
+ */
+void ll_df_read_ant_inf(uint8_t *switch_sample_rates,
+			uint8_t *num_ant,
+			uint8_t *max_switch_pattern_len,
+			uint8_t *max_cte_len)
+{
+	/* Currently filled with data that inform about
+	 * lack of antenna support for Direction Finding
+	 */
+	*switch_sample_rates = 0;
+	*num_ant = 0;
+	*max_switch_pattern_len = 0;
+	*max_cte_len = 0;
+}

subsys/bluetooth/controller/ll_sw/ull_df.h

@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2018-2020 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/* @brief Direction Finding switching sampling rates
+ *
+ * The enum provides information about supported switching
+ * and sampling rates in different Direction Finding types:
+ * - Angle of departure: 1us switching for transmission
+ * - Angle of departure 1us sampling for reception
+ * - Angle of arrival 1us switching-sampling for reception.
+ *
+ * @note Pay attention that both types AoD and AoA
+ * support 2US swiching-sampling as mandatory.
+ */
+enum df_switch_sample_support {
+	DF_AOD_1US_TX   = BIT(0),
+	DF_AOD_1US_RX   = BIT(1),
+	DF_AOA_1US      = BIT(2)
+};

subsys/bluetooth/host/direction.c

@@ -20,7 +20,7 @@
  * @param[out] num_ant                  Antennae number.
  * @param[out] max_switch_pattern_len   Maximum supported antennae switching
  *                                      paterns length.
- * @param[out] max_CTE_len              Maximum length of CTE in 8[us] units.
+ * @param[out] max_cte_len              Maximum length of CTE in 8[us] units.
  *
  * @return Zero in case of success, other value in case of failure.
  */