Bluetooth: HFP_HF: Transmit DTMF Code

Add a function `bt_hfp_hf_transmit_dtmf_code` to transmit DTMF Codes.

Signed-off-by: Lyle Zhu <[email protected]>

Author: lylezhu2012

include/zephyr/bluetooth/classic/hfp_hf.h

@@ -791,6 +791,20 @@ int bt_hfp_hf_ready_to_accept_audio(struct bt_hfp_hf *hf);
  */
 int bt_hfp_hf_request_phone_number(struct bt_hfp_hf *hf);
 
+/** @brief Handsfree HF Transmit A specific DTMF Code
+ *
+ *  During an ongoing call, the HF transmits the AT+VTS command to
+ *  instruct the AG to transmit a specific DTMF code to its network
+ *  connection.
+ *  The set of the code is "0-9,#,*,A-D".
+ *
+ *  @param call HFP HF call object.
+ *  @param code A specific DTMF code.
+ *
+ *  @return 0 in case of success or negative value in case of error.
+ */
+int bt_hfp_hf_transmit_dtmf_code(struct bt_hfp_hf_call *call, char code);
+
 #ifdef __cplusplus
 }
 #endif

subsys/bluetooth/host/classic/hfp_hf.c

@@ -2334,6 +2334,59 @@ int bt_hfp_hf_request_phone_number(struct bt_hfp_hf *hf)
 	return err;
 }
 
+static int vts_finish(struct at_client *hf_at, enum at_result result,
+		   enum at_cme cme_err)
+{
+	struct bt_hfp_hf *hf = CONTAINER_OF(hf_at, struct bt_hfp_hf, at);
+
+	LOG_DBG("AT+VTS (result %d) on %p", result, hf);
+
+	return 0;
+}
+
+int bt_hfp_hf_transmit_dtmf_code(struct bt_hfp_hf_call *call, char code)
+{
+	struct bt_hfp_hf *hf;
+	int err;
+
+	LOG_DBG("");
+
+	if (!call) {
+		LOG_ERR("Invalid call");
+		return -ENOTCONN;
+	}
+
+	hf = call->hf;
+	if (!hf) {
+		LOG_ERR("No HF connection found");
+		return -ENOTCONN;
+	}
+
+	if (!atomic_test_bit(hf->flags, BT_HFP_HF_FLAG_CONNECTED)) {
+		LOG_ERR("SLC is not established on %p", hf);
+		return -ENOTCONN;
+	}
+
+	if (!atomic_test_bit(call->flags, BT_HFP_HF_CALL_IN_USING) ||
+		(!(!atomic_test_bit(call->flags, BT_HFP_HF_CALL_INCOMING_HELD) &&
+		(atomic_get(call->state) == BT_HFP_HF_CALL_STATE_ACTIVE)))) {
+		LOG_ERR("Invalid call status");
+		return -EINVAL;
+	}
+
+	if (!IS_VALID_DTMF(code)) {
+		LOG_ERR("Invalid code");
+		return -EINVAL;
+	}
+
+	err = hfp_hf_send_cmd(hf, NULL, vts_finish, "AT+VTS=%c", code);
+	if (err < 0) {
+		LOG_ERR("Fail to tramsit DTMF Codes on %p", hf);
+	}
+
+	return err;
+}
+
 static int ata_finish(struct at_client *hf_at, enum at_result result,
 		   enum at_cme cme_err)
 {

subsys/bluetooth/host/classic/hfp_internal.h

@@ -357,3 +357,6 @@ enum hfp_hf_ag_indicators {
 #define BT_HFP_BVRA_STATE_SEND_AUDIO BIT(1)
 /* BVRA VRE state: the AG is processing the audio input */
 #define BT_HFP_BVRA_STATE_PROCESS_AUDIO BIT(2)
+
+#define IS_VALID_DTMF(c) ((((c) >= '0') && ((c) <= '9')) || \
+	(((c) >= 'A') && ((c) <= 'D')) || ((c) == '#') || ((c) == '*'))