Bluetooth: host: Add read antenna information HCI command

Add Bluetooth 5.1 Direction Finding HCI command:
HCI_LE_Read_Antenna_Information handling to Host.
Add wrapper function to handle send the command
and receive response from Controller.

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

include/bluetooth/hci.h

@@ -1351,6 +1351,28 @@ struct bt_hci_cp_le_set_privacy_mode {
 	uint8_t         mode;
 } __packed;
 
+#define BT_HCI_LE_1US_AOD_TX                    BIT(0)
+#define BT_HCI_LE_1US_AOD_RX                    BIT(1)
+#define BT_HCI_LE_1US_AOA_RX                    BIT(2)
+
+#define BT_HCI_LE_NUM_ANT_MIN                   0x1
+#define BT_HCI_LE_NUM_ANT_MAX                   0x4B
+
+#define BT_HCI_LE_MAX_SWITCH_PATTERN_LEN_MIN    0x2
+#define BT_HCI_LE_MAX_SWITCH_PATTERN_LEN_MAX    0x4B
+
+#define BT_HCI_LE_MAX_CTE_LEN_MIN               0x2
+#define BT_HCI_LE_MAX_CTE_LEN_MAX               0x14
+
+#define BT_HCI_OP_LE_READ_ANT_INFO              BT_OP(BT_OGF_LE, 0x0058)
+struct bt_hci_rp_le_read_ant_info {
+	uint8_t status;
+	uint8_t switch_sample_rates;
+	uint8_t num_ant;
+	uint8_t max_switch_pattern_len;
+	uint8_t max_cte_len;
+};
+
 #define BT_HCI_OP_LE_SET_PER_ADV_RECV_ENABLE     BT_OP(BT_OGF_LE, 0x0059)
 struct bt_hci_cp_le_set_per_adv_recv_enable {
 	uint16_t handle;

subsys/bluetooth/host/CMakeLists.txt

@@ -57,6 +57,12 @@ if(CONFIG_BT_HCI_HOST)
         )
     endif()
   endif()
+
+  if(CONFIG_BT_DF)
+    zephyr_library_sources(
+      direction.c
+      )
+  endif()
 endif()
 
 if(CONFIG_BT_DEBUG_SMP OR CONFIG_BT_DEBUG_KEYS)

subsys/bluetooth/host/Kconfig

@@ -601,6 +601,13 @@ config BT_ID_MAX
 	  Maximum number of supported local identity addresses. For most
 	  products this is safe to leave as the default value (1).
 
+config BT_DF
+	bool "Enable Direction Finding support [EXPERIMENTAL]"
+	help
+	  Enable support for Bluetooth 5.1 Direction Finding.
+	  It will allow to: get information about antennae, configure
+	  Constant Tone Extension, transmit CTE and sample incoming CTE.
+
 endif # BT_HCI_HOST
 
 config BT_ECC

subsys/bluetooth/host/direction.c

@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2020 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include <stdint.h>
+#include <assert.h>
+
+#include <bluetooth/hci.h>
+#include <sys/byteorder.h>
+
+#define BT_DBG_ENABLED IS_ENABLED(CONFIG_BT_DEBUG_HCI_CORE)
+#define LOG_MODULE_NAME bt_df
+#include "common/log.h"
+
+/* @brief Function provides information about DF antennae numer and
+ *	  controller capabilities related with Constant Tone Extension.
+ *
+ * @param[out] switch_sample_rates      Optional switching and sampling rates.
+ * @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.
+ *
+ * @return Zero in case of success, other value in case of failure.
+ */
+static int hci_df_read_ant_info(uint8_t *switch_sample_rates,
+				uint8_t *num_ant,
+				uint8_t *max_switch_pattern_len,
+				uint8_t *max_cte_len)
+{
+	__ASSERT_NO_MSG(switch_sample_rates);
+	__ASSERT_NO_MSG(num_ant);
+	__ASSERT_NO_MSG(max_switch_pattern_len);
+	__ASSERT_NO_MSG(max_cte_len);
+
+	struct bt_hci_rp_le_read_ant_info *rp;
+	struct net_buf *rsp;
+	int err;
+
+	err = bt_hci_cmd_send_sync(BT_HCI_OP_LE_READ_ANT_INFO, NULL, &rsp);
+	if (err) {
+		BT_ERR("Failed to read antenna information");
+		return err;
+	}
+
+	rp = (void *)rsp->data;
+
+	BT_DBG("DF: sw. sampl rates: %x ant num: %u , max sw. pattern len: %u,"
+	       "max CTE len %d", rp->switch_sample_rates, rp->num_ant,
+	       rp->max_switch_pattern_len, rp->max_cte_len);
+
+	*switch_sample_rates = rp->switch_sample_rates;
+	*num_ant = rp->num_ant;
+	*max_switch_pattern_len = rp->max_switch_pattern_len;
+	*max_cte_len = rp->max_cte_len;
+
+	net_buf_unref(rsp);
+
+	return 0;
+}