NFC: trf7970a: Add Target Mode Detection Support

Add the ability to detect the mode (i.e., RF technology)
used by the initiator.  The RF technology that was
detected can be retrieved by calling the 'tg_get_rf_tech'
driver hook.
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/nfc/trf7970a.c

@@ -340,6 +340,39 @@
 #define TRF7970A_NFC_TARGET_LEVEL_LD_S_7BYTES	(0x1 << 6)
 #define TRF7970A_NFC_TARGET_LEVEL_LD_S_10BYTES	(0x2 << 6)
 
+#define TRF79070A_NFC_TARGET_PROTOCOL_NFCBR_106		BIT(0)
+#define TRF79070A_NFC_TARGET_PROTOCOL_NFCBR_212		BIT(1)
+#define TRF79070A_NFC_TARGET_PROTOCOL_NFCBR_424		(BIT(0) | BIT(1))
+#define TRF79070A_NFC_TARGET_PROTOCOL_PAS_14443B	BIT(2)
+#define TRF79070A_NFC_TARGET_PROTOCOL_PAS_106		BIT(3)
+#define TRF79070A_NFC_TARGET_PROTOCOL_FELICA		BIT(4)
+#define TRF79070A_NFC_TARGET_PROTOCOL_RF_L		BIT(6)
+#define TRF79070A_NFC_TARGET_PROTOCOL_RF_H		BIT(7)
+
+#define TRF79070A_NFC_TARGET_PROTOCOL_106A		\
+	 (TRF79070A_NFC_TARGET_PROTOCOL_RF_H |		\
+	  TRF79070A_NFC_TARGET_PROTOCOL_RF_L |		\
+	  TRF79070A_NFC_TARGET_PROTOCOL_PAS_106 |	\
+	  TRF79070A_NFC_TARGET_PROTOCOL_NFCBR_106)
+
+#define TRF79070A_NFC_TARGET_PROTOCOL_106B		\
+	 (TRF79070A_NFC_TARGET_PROTOCOL_RF_H |		\
+	  TRF79070A_NFC_TARGET_PROTOCOL_RF_L |		\
+	  TRF79070A_NFC_TARGET_PROTOCOL_PAS_14443B |	\
+	  TRF79070A_NFC_TARGET_PROTOCOL_NFCBR_106)
+
+#define TRF79070A_NFC_TARGET_PROTOCOL_212F		\
+	 (TRF79070A_NFC_TARGET_PROTOCOL_RF_H |		\
+	  TRF79070A_NFC_TARGET_PROTOCOL_RF_L |		\
+	  TRF79070A_NFC_TARGET_PROTOCOL_FELICA |	\
+	  TRF79070A_NFC_TARGET_PROTOCOL_NFCBR_212)
+
+#define TRF79070A_NFC_TARGET_PROTOCOL_424F		\
+	 (TRF79070A_NFC_TARGET_PROTOCOL_RF_H |		\
+	  TRF79070A_NFC_TARGET_PROTOCOL_RF_L |		\
+	  TRF79070A_NFC_TARGET_PROTOCOL_FELICA |	\
+	  TRF79070A_NFC_TARGET_PROTOCOL_NFCBR_424)
+
 #define TRF7970A_FIFO_STATUS_OVERFLOW		BIT(7)
 
 /* NFC (ISO/IEC 14443A) Type 2 Tag commands */
@@ -385,6 +418,7 @@ enum trf7970a_state {
 	TRF7970A_ST_WAIT_FOR_RX_DATA_CONT,
 	TRF7970A_ST_WAIT_TO_ISSUE_EOF,
 	TRF7970A_ST_LISTENING,
+	TRF7970A_ST_LISTENING_MD,
 	TRF7970A_ST_MAX
 };
 
@@ -409,6 +443,7 @@ struct trf7970a {
 	unsigned int			guard_time;
 	int				technology;
 	int				framing;
+	u8				md_rf_tech;
 	u8				tx_cmd;
 	bool				issue_eof;
 	int				en2_gpio;
@@ -516,6 +551,58 @@ static int trf7970a_read_irqstatus(struct trf7970a *trf, u8 *status)
 	return ret;
 }
 
+static int trf7970a_read_target_proto(struct trf7970a *trf, u8 *target_proto)
+{
+	int ret;
+	u8 buf[2];
+	u8 addr;
+
+	addr = TRF79070A_NFC_TARGET_PROTOCOL | TRF7970A_CMD_BIT_RW |
+		TRF7970A_CMD_BIT_CONTINUOUS;
+
+	ret = spi_write_then_read(trf->spi, &addr, 1, buf, 2);
+	if (ret)
+		dev_err(trf->dev, "%s - target_proto: Read failed: %d\n",
+				__func__, ret);
+	else
+		*target_proto = buf[0];
+
+	return ret;
+}
+
+static int trf7970a_mode_detect(struct trf7970a *trf, u8 *rf_tech)
+{
+	int ret;
+	u8 target_proto, tech;
+
+	ret = trf7970a_read_target_proto(trf, &target_proto);
+	if (ret)
+		return ret;
+
+	switch (target_proto) {
+	case TRF79070A_NFC_TARGET_PROTOCOL_106A:
+		tech = NFC_DIGITAL_RF_TECH_106A;
+		break;
+	case TRF79070A_NFC_TARGET_PROTOCOL_106B:
+		tech = NFC_DIGITAL_RF_TECH_106B;
+		break;
+	case TRF79070A_NFC_TARGET_PROTOCOL_212F:
+		tech = NFC_DIGITAL_RF_TECH_212F;
+		break;
+	case TRF79070A_NFC_TARGET_PROTOCOL_424F:
+		tech = NFC_DIGITAL_RF_TECH_424F;
+		break;
+	default:
+		dev_dbg(trf->dev, "%s - mode_detect: target_proto: 0x%x\n",
+				__func__, target_proto);
+		return -EIO;
+	}
+
+	*rf_tech = tech;
+
+	return ret;
+}
+
 static void trf7970a_send_upstream(struct trf7970a *trf)
 {
 	dev_kfree_skb_any(trf->tx_skb);
@@ -867,6 +954,22 @@ static irqreturn_t trf7970a_irq(int irq, void *dev_id)
 			trf7970a_send_err_upstream(trf, -EIO);
 		}
 		break;
+	case TRF7970A_ST_LISTENING_MD:
+		if (status & TRF7970A_IRQ_STATUS_SRX) {
+			trf->ignore_timeout =
+				!cancel_delayed_work(&trf->timeout_work);
+
+			ret = trf7970a_mode_detect(trf, &trf->md_rf_tech);
+			if (ret) {
+				trf7970a_send_err_upstream(trf, ret);
+			} else {
+				trf->state = TRF7970A_ST_LISTENING;
+				trf7970a_drain_fifo(trf, status);
+			}
+		} else if (!(status & TRF7970A_IRQ_STATUS_NFC_RF)) {
+			trf7970a_send_err_upstream(trf, -EIO);
+		}
+		break;
 	default:
 		dev_err(trf->dev, "%s - Driver in invalid state: %d\n",
 				__func__, trf->state);
@@ -1587,15 +1690,12 @@ static int trf7970a_tg_configure_hw(struct nfc_digital_dev *ddev, int type,
 	return ret;
 }
 
-static int trf7970a_tg_listen(struct nfc_digital_dev *ddev, u16 timeout,
-		nfc_digital_cmd_complete_t cb, void *arg)
+static int _trf7970a_tg_listen(struct nfc_digital_dev *ddev, u16 timeout,
+		nfc_digital_cmd_complete_t cb, void *arg, bool mode_detect)
 {
 	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);
 	int ret;
 
-	dev_dbg(trf->dev, "Listen - state: %d, timeout: %d ms\n",
-			trf->state, timeout);
-
 	mutex_lock(&trf->lock);
 
 	if ((trf->state != TRF7970A_ST_IDLE) &&
@@ -1654,7 +1754,8 @@ static int trf7970a_tg_listen(struct nfc_digital_dev *ddev, u16 timeout,
 	if (ret)
 		goto out_err;
 
-	trf->state = TRF7970A_ST_LISTENING;
+	trf->state = mode_detect ? TRF7970A_ST_LISTENING_MD :
+				   TRF7970A_ST_LISTENING;
 
 	schedule_delayed_work(&trf->timeout_work, msecs_to_jiffies(timeout));
 
@@ -1663,6 +1764,51 @@ static int trf7970a_tg_listen(struct nfc_digital_dev *ddev, u16 timeout,
 	return ret;
 }
 
+static int trf7970a_tg_listen(struct nfc_digital_dev *ddev, u16 timeout,
+		nfc_digital_cmd_complete_t cb, void *arg)
+{
+	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);
+
+	dev_dbg(trf->dev, "Listen - state: %d, timeout: %d ms\n",
+			trf->state, timeout);
+
+	return _trf7970a_tg_listen(ddev, timeout, cb, arg, false);
+}
+
+static int trf7970a_tg_listen_md(struct nfc_digital_dev *ddev,
+		u16 timeout, nfc_digital_cmd_complete_t cb, void *arg)
+{
+	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);
+	int ret;
+
+	dev_dbg(trf->dev, "Listen MD - state: %d, timeout: %d ms\n",
+			trf->state, timeout);
+
+	ret = trf7970a_tg_configure_hw(ddev, NFC_DIGITAL_CONFIG_RF_TECH,
+			NFC_DIGITAL_RF_TECH_106A);
+	if (ret)
+		return ret;
+
+	ret = trf7970a_tg_configure_hw(ddev, NFC_DIGITAL_CONFIG_FRAMING,
+			NFC_DIGITAL_FRAMING_NFCA_NFC_DEP);
+	if (ret)
+		return ret;
+
+	return _trf7970a_tg_listen(ddev, timeout, cb, arg, true);
+}
+
+static int trf7970a_tg_get_rf_tech(struct nfc_digital_dev *ddev, u8 *rf_tech)
+{
+	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);
+
+	dev_dbg(trf->dev, "Get RF Tech - state: %d, rf_tech: %d\n",
+			trf->state, trf->md_rf_tech);
+
+	*rf_tech = trf->md_rf_tech;
+
+	return 0;
+}
+
 static void trf7970a_abort_cmd(struct nfc_digital_dev *ddev)
 {
 	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);
@@ -1696,6 +1842,8 @@ static struct nfc_digital_ops trf7970a_nfc_ops = {
 	.tg_configure_hw	= trf7970a_tg_configure_hw,
 	.tg_send_cmd		= trf7970a_send_cmd,
 	.tg_listen		= trf7970a_tg_listen,
+	.tg_listen_md		= trf7970a_tg_listen_md,
+	.tg_get_rf_tech		= trf7970a_tg_get_rf_tech,
 	.switch_rf		= trf7970a_switch_rf,
 	.abort_cmd		= trf7970a_abort_cmd,
 };