NFC: trf7970a: Add driver with ISO/IEC 14443 Type 2 Tag Support

Add a driver for the Texas Instruments TRF7970a RFID/NFC/15693
transceiver.  The driver currently supports ISO/IEC 14443 Type 2
tags only (MIFARE Ultralight and Ultralight C but not Classic).

CC: Erick Macias <emacias@ti.com>
CC: Felipe Balbi <balbi@ti.com>
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

3 files changed, 1237 insertions, 0 deletions

diff --git a/drivers/nfc/Kconfig b/drivers/nfc/Kconfig
index fe20e1cc054..65d4ca19d13 100644
--- a/drivers/nfc/Kconfig
+++ b/drivers/nfc/Kconfig
@@ -26,6 +26,18 @@ config NFC_WILINK
 	  Say Y here to compile support for Texas Instrument's NFC WiLink driver
 	  into the kernel or say M to compile it as module.
 
+config NFC_TRF7970A
+	tristate "Texas Instruments TRF7970a NFC driver"
+	depends on SPI && NFC_DIGITAL
+	help
+	  This option enables the NFC driver for Texas Instruments' TRF7970a
+	  device. Such device supports 5 different protocols: ISO14443A,
+	  ISO14443B, FeLiCa, ISO15693 and ISO18000-3.
+
+	  Say Y here to compile support for TRF7970a into the kernel or
+	  say M  to compile it as a module. The module will be called
+	  trf7970a.ko.
+
 config NFC_MEI_PHY
 	tristate "MEI bus NFC device support"
 	depends on INTEL_MEI && NFC_HCI
diff --git a/drivers/nfc/Makefile b/drivers/nfc/Makefile
index 56ab822ba03..ae42a3fa60c 100644
--- a/drivers/nfc/Makefile
+++ b/drivers/nfc/Makefile
@@ -10,5 +10,6 @@ obj-$(CONFIG_NFC_MEI_PHY)	+= mei_phy.o
 obj-$(CONFIG_NFC_SIM)		+= nfcsim.o
 obj-$(CONFIG_NFC_PORT100)	+= port100.o
 obj-$(CONFIG_NFC_MRVL)		+= nfcmrvl/
+obj-$(CONFIG_NFC_TRF7970A)	+= trf7970a.o
 
 ccflags-$(CONFIG_NFC_DEBUG) := -DDEBUG
diff --git a/drivers/nfc/trf7970a.c b/drivers/nfc/trf7970a.c
new file mode 100644
index 00000000000..0d62d45d688
--- /dev/null
+++ b/drivers/nfc/trf7970a.c
@@ -0,0 +1,1224 @@
+/*
+ * TI TRF7970a RFID/NFC Transceiver Driver
+ *
+ * Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com
+ *
+ * Author: Erick Macias <emacias@ti.com>
+ * Author: Felipe Balbi <balbi@ti.com>
+ * Author: Mark A. Greer <mgreer@animalcreek.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2  of
+ * the License as published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/netdevice.h>
+#include <linux/interrupt.h>
+#include <linux/nfc.h>
+#include <linux/skbuff.h>
+#include <linux/delay.h>
+#include <linux/gpio.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <linux/spi/spi.h>
+#include <linux/regulator/consumer.h>
+
+#include <net/nfc/nfc.h>
+#include <net/nfc/digital.h>
+
+/* There are 3 ways the host can communicate with the trf7970a:
+ * parallel mode, SPI with Slave Select (SS) mode, and SPI without
+ * SS mode.  The driver only supports the two SPI modes.
+ *
+ * The trf7970a is very timing sensitive and the VIN, EN2, and EN
+ * pins must asserted in that order and with specific delays in between.
+ * The delays used in the driver were provided by TI and have been
+ * confirmed to work with this driver.
+ *
+ * Timeouts are implemented using the delayed workqueue kernel facility.
+ * Timeouts are required so things don't hang when there is no response
+ * from the trf7970a (or tag).  Using this mechanism creates a race with
+ * interrupts, however.  That is, an interrupt and a timeout could occur
+ * closely enough together that one is blocked by the mutex while the other
+ * executes.  When the timeout handler executes first and blocks the
+ * interrupt handler, it will eventually set the state to IDLE so the
+ * interrupt handler will check the state and exit with no harm done.
+ * When the interrupt handler executes first and blocks the timeout handler,
+ * the cancel_delayed_work() call will know that it didn't cancel the
+ * work item (i.e., timeout) and will return zero.  That return code is
+ * used by the timer handler to indicate that it should ignore the timeout
+ * once its unblocked.
+ *
+ * Aborting an active command isn't as simple as it seems because the only
+ * way to abort a command that's already been sent to the tag is so turn
+ * off power to the tag.  If we do that, though, we'd have to go through
+ * the entire anticollision procedure again but the digital layer doesn't
+ * support that.  So, if an abort is received before trf7970a_in_send_cmd()
+ * has sent the command to the tag, it simply returns -ECANCELED.  If the
+ * command has already been sent to the tag, then the driver continues
+ * normally and recieves the response data (or error) but just before
+ * sending the data upstream, it frees the rx_skb and sends -ECANCELED
+ * upstream instead.  If the command failed, that error will be sent
+ * upstream.
+ *
+ * When recieving data from a tag and the interrupt status register has
+ * only the SRX bit set, it means that all of the data has been received
+ * (once what's in the fifo has been read).  However, depending on timing
+ * an interrupt status with only the SRX bit set may not be recived.  In
+ * those cases, the timeout mechanism is used to wait 5 ms in case more
+ * data arrives.  After 5 ms, it is assumed that all of the data has been
+ * received and the accumulated rx data is sent upstream.  The
+ * 'TRF7970A_ST_WAIT_FOR_RX_DATA_CONT' state is used for this purpose
+ * (i.e., it indicates that some data has been received but we're not sure
+ * if there is more coming so a timeout in this state means all data has
+ * been received and there isn't an error).  The delay is 5 ms since delays
+ * over 2 ms have been observed during testing (a little extra just in case).
+ *
+ * Type 2 write and sector select commands respond with a 4-bit ACK or NACK.
+ * Having only 4 bits in the FIFO won't normally generate an interrupt so
+ * driver enables the '4_bit_RX' bit of the Special Functions register 1
+ * to cause an interrupt in that case.  Leaving that bit for a read command
+ * messes up the data returned so it is only enabled when the framing is
+ * 'NFC_DIGITAL_FRAMING_NFCA_T2T' and the command is not a read command.
+ * Unfortunately, that means that the driver has to peek into tx frames
+ * when the framing is 'NFC_DIGITAL_FRAMING_NFCA_T2T'.  This is done by
+ * the trf7970a_per_cmd_config() routine.
+ */
+
+#define TRF7970A_SUPPORTED_PROTOCOLS		NFC_PROTO_MIFARE_MASK
+
+/* TX data must be prefixed with a FIFO reset cmd, a cmd that depends
+ * on what the current framing is, the address of the TX length byte 1
+ * register (0x1d), and the 2 byte length of the data to be transmitted.
+ * That totals 5 bytes.
+ */
+#define TRF7970A_TX_SKB_HEADROOM		5
+
+#define TRF7970A_RX_SKB_ALLOC_SIZE		256
+
+#define TRF7970A_FIFO_SIZE			128
+
+/* TX length is 3 nibbles long ==> 4KB - 1 bytes max */
+#define TRF7970A_TX_MAX				(4096 - 1)
+
+#define TRF7970A_WAIT_FOR_RX_DATA_TIMEOUT	5
+#define TRF7970A_WAIT_FOR_FIFO_DRAIN_TIMEOUT	3
+
+/* Quirks */
+/* Erratum: When reading IRQ Status register on trf7970a, we must issue a
+ * read continuous command for IRQ Status and Collision Position registers.
+ */
+#define TRF7970A_QUIRK_IRQ_STATUS_READ_ERRATA	BIT(0)
+
+/* Direct commands */
+#define TRF7970A_CMD_IDLE			0x00
+#define TRF7970A_CMD_SOFT_INIT			0x03
+#define TRF7970A_CMD_RF_COLLISION		0x04
+#define TRF7970A_CMD_RF_COLLISION_RESPONSE_N	0x05
+#define TRF7970A_CMD_RF_COLLISION_RESPONSE_0	0x06
+#define TRF7970A_CMD_FIFO_RESET			0x0f
+#define TRF7970A_CMD_TRANSMIT_NO_CRC		0x10
+#define TRF7970A_CMD_TRANSMIT			0x11
+#define TRF7970A_CMD_DELAY_TRANSMIT_NO_CRC	0x12
+#define TRF7970A_CMD_DELAY_TRANSMIT		0x13
+#define TRF7970A_CMD_EOF			0x14
+#define TRF7970A_CMD_CLOSE_SLOT			0x15
+#define TRF7970A_CMD_BLOCK_RX			0x16
+#define TRF7970A_CMD_ENABLE_RX			0x17
+#define TRF7970A_CMD_TEST_EXT_RF		0x18
+#define TRF7970A_CMD_TEST_INT_RF		0x19
+#define TRF7970A_CMD_RX_GAIN_ADJUST		0x1a
+
+/* Bits determining whether its a direct command or register R/W,
+ * whether to use a continuous SPI transaction or not, and the actual
+ * direct cmd opcode or regster address.
+ */
+#define TRF7970A_CMD_BIT_CTRL			BIT(7)
+#define TRF7970A_CMD_BIT_RW			BIT(6)
+#define TRF7970A_CMD_BIT_CONTINUOUS		BIT(5)
+#define TRF7970A_CMD_BIT_OPCODE(opcode)		((opcode) & 0x1f)
+
+/* Registers addresses */
+#define TRF7970A_CHIP_STATUS_CTRL		0x00
+#define TRF7970A_ISO_CTRL			0x01
+#define TRF7970A_ISO14443B_TX_OPTIONS		0x02
+#define TRF7970A_ISO14443A_HIGH_BITRATE_OPTIONS	0x03
+#define TRF7970A_TX_TIMER_SETTING_H_BYTE	0x04
+#define TRF7970A_TX_TIMER_SETTING_L_BYTE	0x05
+#define TRF7970A_TX_PULSE_LENGTH_CTRL		0x06
+#define TRF7970A_RX_NO_RESPONSE_WAIT		0x07
+#define TRF7970A_RX_WAIT_TIME			0x08
+#define TRF7970A_MODULATOR_SYS_CLK_CTRL		0x09
+#define TRF7970A_RX_SPECIAL_SETTINGS		0x0a
+#define TRF7970A_REG_IO_CTRL			0x0b
+#define TRF7970A_IRQ_STATUS			0x0c
+#define TRF7970A_COLLISION_IRQ_MASK		0x0d
+#define TRF7970A_COLLISION_POSITION		0x0e
+#define TRF7970A_RSSI_OSC_STATUS		0x0f
+#define TRF7970A_SPECIAL_FCN_REG1		0x10
+#define TRF7970A_SPECIAL_FCN_REG2		0x11
+#define TRF7970A_RAM1				0x12
+#define TRF7970A_RAM2				0x13
+#define TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS	0x14
+#define TRF7970A_NFC_LOW_FIELD_LEVEL		0x16
+#define TRF7970A_NFCID1				0x17
+#define TRF7970A_NFC_TARGET_LEVEL		0x18
+#define TRF79070A_NFC_TARGET_PROTOCOL		0x19
+#define TRF7970A_TEST_REGISTER1			0x1a
+#define TRF7970A_TEST_REGISTER2			0x1b
+#define TRF7970A_FIFO_STATUS			0x1c
+#define TRF7970A_TX_LENGTH_BYTE1		0x1d
+#define TRF7970A_TX_LENGTH_BYTE2		0x1e
+#define TRF7970A_FIFO_IO_REGISTER		0x1f
+
+/* Chip Status Control Register Bits */
+#define TRF7970A_CHIP_STATUS_VRS5_3		BIT(0)
+#define TRF7970A_CHIP_STATUS_REC_ON		BIT(1)
+#define TRF7970A_CHIP_STATUS_AGC_ON		BIT(2)
+#define TRF7970A_CHIP_STATUS_PM_ON		BIT(3)
+#define TRF7970A_CHIP_STATUS_RF_PWR		BIT(4)
+#define TRF7970A_CHIP_STATUS_RF_ON		BIT(5)
+#define TRF7970A_CHIP_STATUS_DIRECT		BIT(6)
+#define TRF7970A_CHIP_STATUS_STBY		BIT(7)
+
+/* ISO Control Register Bits */
+#define TRF7970A_ISO_CTRL_15693_SGL_1OF4_662	0x00
+#define TRF7970A_ISO_CTRL_15693_SGL_1OF256_662	0x01
+#define TRF7970A_ISO_CTRL_15693_SGL_1OF4_2648	0x02
+#define TRF7970A_ISO_CTRL_15693_SGL_1OF256_2648	0x03
+#define TRF7970A_ISO_CTRL_15693_DBL_1OF4_667a	0x04
+#define TRF7970A_ISO_CTRL_15693_DBL_1OF256_667	0x05
+#define TRF7970A_ISO_CTRL_15693_DBL_1OF4_2669	0x06
+#define TRF7970A_ISO_CTRL_15693_DBL_1OF256_2669	0x07
+#define TRF7970A_ISO_CTRL_14443A_106		0x08
+#define TRF7970A_ISO_CTRL_14443A_212		0x09
+#define TRF7970A_ISO_CTRL_14443A_424		0x0a
+#define TRF7970A_ISO_CTRL_14443A_848		0x0b
+#define TRF7970A_ISO_CTRL_14443B_106		0x0c
+#define TRF7970A_ISO_CTRL_14443B_212		0x0d
+#define TRF7970A_ISO_CTRL_14443B_424		0x0e
+#define TRF7970A_ISO_CTRL_14443B_848		0x0f
+#define TRF7970A_ISO_CTRL_FELICA_212		0x1a
+#define TRF7970A_ISO_CTRL_FELICA_424		0x1b
+#define TRF7970A_ISO_CTRL_RFID			BIT(5)
+#define TRF7970A_ISO_CTRL_DIR_MODE		BIT(6)
+#define TRF7970A_ISO_CTRL_RX_CRC_N		BIT(7)	/* true == No CRC */
+
+#define TRF7970A_ISO_CTRL_RFID_SPEED_MASK	0x1f
+
+/* Modulator and SYS_CLK Control Register Bits */
+#define TRF7970A_MODULATOR_DEPTH(n)		((n) & 0x7)
+#define TRF7970A_MODULATOR_DEPTH_ASK10		(TRF7970A_MODULATOR_DEPTH(0))
+#define TRF7970A_MODULATOR_DEPTH_OOK		(TRF7970A_MODULATOR_DEPTH(1))
+#define TRF7970A_MODULATOR_DEPTH_ASK7		(TRF7970A_MODULATOR_DEPTH(2))
+#define TRF7970A_MODULATOR_DEPTH_ASK8_5		(TRF7970A_MODULATOR_DEPTH(3))
+#define TRF7970A_MODULATOR_DEPTH_ASK13		(TRF7970A_MODULATOR_DEPTH(4))
+#define TRF7970A_MODULATOR_DEPTH_ASK16		(TRF7970A_MODULATOR_DEPTH(5))
+#define TRF7970A_MODULATOR_DEPTH_ASK22		(TRF7970A_MODULATOR_DEPTH(6))
+#define TRF7970A_MODULATOR_DEPTH_ASK30		(TRF7970A_MODULATOR_DEPTH(7))
+#define TRF7970A_MODULATOR_EN_ANA		BIT(3)
+#define TRF7970A_MODULATOR_CLK(n)		(((n) & 0x3) << 4)
+#define TRF7970A_MODULATOR_CLK_DISABLED		(TRF7970A_MODULATOR_CLK(0))
+#define TRF7970A_MODULATOR_CLK_3_6		(TRF7970A_MODULATOR_CLK(1))
+#define TRF7970A_MODULATOR_CLK_6_13		(TRF7970A_MODULATOR_CLK(2))
+#define TRF7970A_MODULATOR_CLK_13_27		(TRF7970A_MODULATOR_CLK(3))
+#define TRF7970A_MODULATOR_EN_OOK		BIT(6)
+#define TRF7970A_MODULATOR_27MHZ		BIT(7)
+
+/* IRQ Status Register Bits */
+#define TRF7970A_IRQ_STATUS_NORESP		BIT(0) /* ISO15693 only */
+#define TRF7970A_IRQ_STATUS_COL			BIT(1)
+#define TRF7970A_IRQ_STATUS_FRAMING_EOF_ERROR	BIT(2)
+#define TRF7970A_IRQ_STATUS_PARITY_ERROR	BIT(3)
+#define TRF7970A_IRQ_STATUS_CRC_ERROR		BIT(4)
+#define TRF7970A_IRQ_STATUS_FIFO		BIT(5)
+#define TRF7970A_IRQ_STATUS_SRX			BIT(6)
+#define TRF7970A_IRQ_STATUS_TX			BIT(7)
+
+#define TRF7970A_IRQ_STATUS_ERROR				\
+		(TRF7970A_IRQ_STATUS_COL |			\
+		 TRF7970A_IRQ_STATUS_FRAMING_EOF_ERROR |	\
+		 TRF7970A_IRQ_STATUS_PARITY_ERROR |		\
+		 TRF7970A_IRQ_STATUS_CRC_ERROR)
+
+#define TRF7970A_SPECIAL_FCN_REG1_COL_7_6		BIT(0)
+#define TRF7970A_SPECIAL_FCN_REG1_14_ANTICOLL		BIT(1)
+#define TRF7970A_SPECIAL_FCN_REG1_4_BIT_RX		BIT(2)
+#define TRF7970A_SPECIAL_FCN_REG1_SP_DIR_MODE		BIT(3)
+#define TRF7970A_SPECIAL_FCN_REG1_NEXT_SLOT_37US	BIT(4)
+#define TRF7970A_SPECIAL_FCN_REG1_PAR43			BIT(5)
+
+#define TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLH_124	(0x0 << 2)
+#define TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLH_120	(0x1 << 2)
+#define TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLH_112	(0x2 << 2)
+#define TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLH_96	(0x3 << 2)
+#define TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLL_4	0x0
+#define TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLL_8	0x1
+#define TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLL_16	0x2
+#define TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLL_32	0x3
+
+#define TRF7970A_FIFO_STATUS_OVERFLOW		BIT(7)
+
+/* NFC (ISO/IEC 14443A) Type 2 Tag commands */
+#define NFC_T2T_CMD_READ			0x30
+
+enum trf7970a_state {
+	TRF7970A_ST_OFF,
+	TRF7970A_ST_IDLE,
+	TRF7970A_ST_IDLE_RX_BLOCKED,
+	TRF7970A_ST_WAIT_FOR_TX_FIFO,
+	TRF7970A_ST_WAIT_FOR_RX_DATA,
+	TRF7970A_ST_WAIT_FOR_RX_DATA_CONT,
+	TRF7970A_ST_MAX
+};
+
+struct trf7970a {
+	enum trf7970a_state		state;
+	struct device			*dev;
+	struct spi_device		*spi;
+	struct regulator		*regulator;
+	struct nfc_digital_dev		*ddev;
+	u32				quirks;
+	bool				powering_up;
+	bool				aborting;
+	struct sk_buff			*tx_skb;
+	struct sk_buff			*rx_skb;
+	nfc_digital_cmd_complete_t	cb;
+	void				*cb_arg;
+	u8				iso_ctrl;
+	u8				special_fcn_reg1;
+	int				technology;
+	int				framing;
+	u8				tx_cmd;
+	int				en2_gpio;
+	int				en_gpio;
+	struct mutex			lock;
+	unsigned int			timeout;
+	bool				ignore_timeout;
+	struct delayed_work		timeout_work;
+};
+
+
+static int trf7970a_cmd(struct trf7970a *trf, u8 opcode)
+{
+	u8 cmd = TRF7970A_CMD_BIT_CTRL | TRF7970A_CMD_BIT_OPCODE(opcode);
+	int ret;
+
+	dev_dbg(trf->dev, "cmd: 0x%x\n", cmd);
+
+	ret = spi_write(trf->spi, &cmd, 1);
+	if (ret)
+		dev_err(trf->dev, "%s - cmd: 0x%x, ret: %d\n", __func__, cmd,
+				ret);
+	return ret;
+}
+
+static int trf7970a_read(struct trf7970a *trf, u8 reg, u8 *val)
+{
+	u8 addr = TRF7970A_CMD_BIT_RW | reg;
+	int ret;
+
+	ret = spi_write_then_read(trf->spi, &addr, 1, val, 1);
+	if (ret)
+		dev_err(trf->dev, "%s - addr: 0x%x, ret: %d\n", __func__, addr,
+				ret);
+
+	dev_dbg(trf->dev, "read(0x%x): 0x%x\n", addr, *val);
+
+	return ret;
+}
+
+static int trf7970a_read_cont(struct trf7970a *trf, u8 reg,
+		u8 *buf, size_t len)
+{
+	u8 addr = reg | TRF7970A_CMD_BIT_RW | TRF7970A_CMD_BIT_CONTINUOUS;
+	int ret;
+
+	dev_dbg(trf->dev, "read_cont(0x%x, %zd)\n", addr, len);
+
+	ret = spi_write_then_read(trf->spi, &addr, 1, buf, len);
+	if (ret)
+		dev_err(trf->dev, "%s - addr: 0x%x, ret: %d\n", __func__, addr,
+				ret);
+	return ret;
+}
+
+static int trf7970a_write(struct trf7970a *trf, u8 reg, u8 val)
+{
+	u8 buf[2] = { reg, val };
+	int ret;
+
+	dev_dbg(trf->dev, "write(0x%x): 0x%x\n", reg, val);
+
+	ret = spi_write(trf->spi, buf, 2);
+	if (ret)
+		dev_err(trf->dev, "%s - write: 0x%x 0x%x, ret: %d\n", __func__,
+				buf[0], buf[1], ret);
+
+	return ret;
+}
+
+static int trf7970a_read_irqstatus(struct trf7970a *trf, u8 *status)
+{
+	int ret;
+	u8 buf[2];
+	u8 addr;
+
+	addr = TRF7970A_IRQ_STATUS | TRF7970A_CMD_BIT_RW;
+
+	if (trf->quirks & TRF7970A_QUIRK_IRQ_STATUS_READ_ERRATA) {
+		addr |= TRF7970A_CMD_BIT_CONTINUOUS;
+		ret = spi_write_then_read(trf->spi, &addr, 1, buf, 2);
+	} else {
+		ret = spi_write_then_read(trf->spi, &addr, 1, buf, 1);
+	}
+
+	if (ret)
+		dev_err(trf->dev, "%s - irqstatus: Status read failed: %d\n",
+				__func__, ret);
+	else
+		*status = buf[0];
+
+	return ret;
+}
+
+static void trf7970a_send_upstream(struct trf7970a *trf)
+{
+	u8 rssi;
+
+	dev_kfree_skb_any(trf->tx_skb);
+	trf->tx_skb = NULL;
+
+	if (trf->rx_skb && !IS_ERR(trf->rx_skb) && !trf->aborting)
+		print_hex_dump_debug("trf7970a rx data: ", DUMP_PREFIX_NONE,
+				16, 1, trf->rx_skb->data, trf->rx_skb->len,
+				false);
+
+	/* According to the manual it is "good form" to reset the fifo and
+	 * read the RSSI levels & oscillator status register here.  It doesn't
+	 * explain why.
+	 */
+	trf7970a_cmd(trf, TRF7970A_CMD_FIFO_RESET);
+	trf7970a_read(trf, TRF7970A_RSSI_OSC_STATUS, &rssi);
+
+	trf->state = TRF7970A_ST_IDLE;
+
+	if (trf->aborting) {
+		dev_dbg(trf->dev, "Abort process complete\n");
+
+		if (!IS_ERR(trf->rx_skb)) {
+			kfree_skb(trf->rx_skb);
+			trf->rx_skb = ERR_PTR(-ECANCELED);
+		}
+
+		trf->aborting = false;
+	}
+
+	trf->cb(trf->ddev, trf->cb_arg, trf->rx_skb);
+
+	trf->rx_skb = NULL;
+}
+
+static void trf7970a_send_err_upstream(struct trf7970a *trf, int errno)
+{
+	dev_dbg(trf->dev, "Error - state: %d, errno: %d\n", trf->state, errno);
+
+	kfree_skb(trf->rx_skb);
+	trf->rx_skb = ERR_PTR(errno);
+
+	trf7970a_send_upstream(trf);
+}
+
+static int trf7970a_transmit(struct trf7970a *trf, struct sk_buff *skb,
+		unsigned int len)
+{
+	unsigned int timeout;
+	int ret;
+
+	print_hex_dump_debug("trf7970a tx data: ", DUMP_PREFIX_NONE,
+			16, 1, skb->data, len, false);
+
+	ret = spi_write(trf->spi, skb->data, len);
+	if (ret) {
+		dev_err(trf->dev, "%s - Can't send tx data: %d\n", __func__,
+				ret);
+		return ret;
+	}
+
+	skb_pull(skb, len);
+
+	if (skb->len > 0) {
+		trf->state = TRF7970A_ST_WAIT_FOR_TX_FIFO;
+		timeout = TRF7970A_WAIT_FOR_FIFO_DRAIN_TIMEOUT;
+	} else {
+		trf->state = TRF7970A_ST_WAIT_FOR_RX_DATA;
+		timeout = trf->timeout;
+	}
+
+	dev_dbg(trf->dev, "Setting timeout for %d ms, state: %d\n", timeout,
+			trf->state);
+
+	schedule_delayed_work(&trf->timeout_work, msecs_to_jiffies(timeout));
+
+	return 0;
+}
+
+static void trf7970a_fill_fifo(struct trf7970a *trf)
+{
+	struct sk_buff *skb = trf->tx_skb;
+	unsigned int len;
+	int ret;
+	u8 fifo_bytes;
+
+	ret = trf7970a_read(trf, TRF7970A_FIFO_STATUS, &fifo_bytes);
+	if (ret) {
+		trf7970a_send_err_upstream(trf, ret);
+		return;
+	}
+
+	dev_dbg(trf->dev, "Filling FIFO - fifo_bytes: 0x%x\n", fifo_bytes);
+
+	if (fifo_bytes & TRF7970A_FIFO_STATUS_OVERFLOW) {
+		dev_err(trf->dev, "%s - fifo overflow: 0x%x\n", __func__,
+				fifo_bytes);
+		trf7970a_send_err_upstream(trf, -EIO);
+		return;
+	}
+
+	/* Calculate how much more data can be written to the fifo */
+	len = TRF7970A_FIFO_SIZE - fifo_bytes;
+	len = min(skb->len, len);
+
+	ret = trf7970a_transmit(trf, skb, len);
+	if (ret)
+		trf7970a_send_err_upstream(trf, ret);
+}
+
+static void trf7970a_drain_fifo(struct trf7970a *trf, u8 status)
+{
+	struct sk_buff *skb = trf->rx_skb;
+	int ret;
+	u8 fifo_bytes;
+
+	if (status & TRF7970A_IRQ_STATUS_ERROR) {
+		trf7970a_send_err_upstream(trf, -EIO);
+		return;
+	}
+
+	ret = trf7970a_read(trf, TRF7970A_FIFO_STATUS, &fifo_bytes);
+	if (ret) {
+		trf7970a_send_err_upstream(trf, ret);
+		return;
+	}
+
+	dev_dbg(trf->dev, "Draining FIFO - fifo_bytes: 0x%x\n", fifo_bytes);
+
+	if (!fifo_bytes)
+		goto no_rx_data;
+
+	if (fifo_bytes & TRF7970A_FIFO_STATUS_OVERFLOW) {
+		dev_err(trf->dev, "%s - fifo overflow: 0x%x\n", __func__,
+				fifo_bytes);
+		trf7970a_send_err_upstream(trf, -EIO);
+		return;
+	}
+
+	if (fifo_bytes > skb_tailroom(skb)) {
+		skb = skb_copy_expand(skb, skb_headroom(skb),
+				max_t(int, fifo_bytes,
+					TRF7970A_RX_SKB_ALLOC_SIZE),
+				GFP_KERNEL);
+		if (!skb) {
+			trf7970a_send_err_upstream(trf, -ENOMEM);
+			return;
+		}
+
+		kfree_skb(trf->rx_skb);
+		trf->rx_skb = skb;
+	}
+
+	ret = trf7970a_read_cont(trf, TRF7970A_FIFO_IO_REGISTER,
+			skb_put(skb, fifo_bytes), fifo_bytes);
+	if (ret) {
+		trf7970a_send_err_upstream(trf, ret);
+		return;
+	}
+
+	/* If received Type 2 ACK/NACK, shift right 4 bits and pass up */
+	if ((trf->framing == NFC_DIGITAL_FRAMING_NFCA_T2T) && (skb->len == 1) &&
+			(trf->special_fcn_reg1 ==
+				 TRF7970A_SPECIAL_FCN_REG1_4_BIT_RX)) {
+		skb->data[0] >>= 4;
+		status = TRF7970A_IRQ_STATUS_SRX;
+	} else {
+		trf->state = TRF7970A_ST_WAIT_FOR_RX_DATA_CONT;
+	}
+
+no_rx_data:
+	if (status == TRF7970A_IRQ_STATUS_SRX) { /* Receive complete */
+		trf7970a_send_upstream(trf);
+		return;
+	}
+
+	dev_dbg(trf->dev, "Setting timeout for %d ms\n",
+			TRF7970A_WAIT_FOR_RX_DATA_TIMEOUT);
+
+	schedule_delayed_work(&trf->timeout_work,
+			msecs_to_jiffies(TRF7970A_WAIT_FOR_RX_DATA_TIMEOUT));
+}
+
+static irqreturn_t trf7970a_irq(int irq, void *dev_id)
+{
+	struct trf7970a *trf = dev_id;
+	int ret;
+	u8 status;
+
+	mutex_lock(&trf->lock);
+
+	if (trf->state == TRF7970A_ST_OFF) {
+		mutex_unlock(&trf->lock);
+		return IRQ_NONE;
+	}
+
+	ret = trf7970a_read_irqstatus(trf, &status);
+	if (ret) {
+		mutex_unlock(&trf->lock);
+		return IRQ_NONE;
+	}
+
+	dev_dbg(trf->dev, "IRQ - state: %d, status: 0x%x\n", trf->state,
+			status);
+
+	if (!status) {
+		mutex_unlock(&trf->lock);
+		return IRQ_NONE;
+	}
+
+	switch (trf->state) {
+	case TRF7970A_ST_IDLE:
+	case TRF7970A_ST_IDLE_RX_BLOCKED:
+		/* If getting interrupts caused by RF noise, turn off the
+		 * receiver to avoid unnecessary interrupts.  It will be
+		 * turned back on in trf7970a_in_send_cmd() when the next
+		 * command is issued.
+		 */
+		if (status & TRF7970A_IRQ_STATUS_ERROR) {
+			trf7970a_cmd(trf, TRF7970A_CMD_BLOCK_RX);
+			trf->state = TRF7970A_ST_IDLE_RX_BLOCKED;
+		}
+
+		trf7970a_cmd(trf, TRF7970A_CMD_FIFO_RESET);
+		break;
+	case TRF7970A_ST_WAIT_FOR_TX_FIFO:
+		if (status & TRF7970A_IRQ_STATUS_TX) {
+			trf->ignore_timeout =
+				!cancel_delayed_work(&trf->timeout_work);
+			trf7970a_fill_fifo(trf);
+		} else {
+			trf7970a_send_err_upstream(trf, -EIO);
+		}
+		break;
+	case TRF7970A_ST_WAIT_FOR_RX_DATA:
+	case TRF7970A_ST_WAIT_FOR_RX_DATA_CONT:
+		if (status & TRF7970A_IRQ_STATUS_SRX) {
+			trf->ignore_timeout =
+				!cancel_delayed_work(&trf->timeout_work);
+			trf7970a_drain_fifo(trf, status);
+		} else if (!(status & TRF7970A_IRQ_STATUS_TX)) {
+			trf7970a_send_err_upstream(trf, -EIO);
+		}
+		break;
+	default:
+		dev_err(trf->dev, "%s - Driver in invalid state: %d\n",
+				__func__, trf->state);
+	}
+
+	mutex_unlock(&trf->lock);
+	return IRQ_HANDLED;
+}
+
+static void trf7970a_timeout_work_handler(struct work_struct *work)
+{
+	struct trf7970a *trf = container_of(work, struct trf7970a,
+			timeout_work.work);
+
+	dev_dbg(trf->dev, "Timeout - state: %d, ignore_timeout: %d\n",
+			trf->state, trf->ignore_timeout);
+
+	mutex_lock(&trf->lock);
+
+	if (trf->ignore_timeout)
+		trf->ignore_timeout = false;
+	else if (trf->state == TRF7970A_ST_WAIT_FOR_RX_DATA_CONT)
+		trf7970a_send_upstream(trf); /* No more rx data so send up */
+	else
+		trf7970a_send_err_upstream(trf, -ETIMEDOUT);
+
+	mutex_unlock(&trf->lock);
+}
+
+static int trf7970a_init(struct trf7970a *trf)
+{
+	int ret;
+
+	dev_dbg(trf->dev, "Initializing device - state: %d\n", trf->state);
+
+	ret = trf7970a_cmd(trf, TRF7970A_CMD_SOFT_INIT);
+	if (ret)
+		goto err_out;
+
+	ret = trf7970a_cmd(trf, TRF7970A_CMD_IDLE);
+	if (ret)
+		goto err_out;
+
+	ret = trf7970a_write(trf, TRF7970A_MODULATOR_SYS_CLK_CTRL,
+			TRF7970A_MODULATOR_DEPTH_OOK);
+	if (ret)
+		goto err_out;
+
+	ret = trf7970a_write(trf, TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS,
+			TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLH_96 |
+			TRF7970A_ADJUTABLE_FIFO_IRQ_LEVELS_WLL_32);
+	if (ret)
+		goto err_out;
+
+	ret = trf7970a_write(trf, TRF7970A_SPECIAL_FCN_REG1, 0);
+	if (ret)
+		goto err_out;
+
+	trf->special_fcn_reg1 = 0;
+
+	ret = trf7970a_write(trf, TRF7970A_CHIP_STATUS_CTRL,
+			TRF7970A_CHIP_STATUS_RF_ON |
+				TRF7970A_CHIP_STATUS_VRS5_3);
+	if (ret)
+		goto err_out;
+
+	return 0;
+
+err_out:
+	dev_dbg(trf->dev, "Couldn't init device: %d\n", ret);
+	return ret;
+}
+
+static void trf7970a_switch_rf_off(struct trf7970a *trf)
+{
+	dev_dbg(trf->dev, "Switching rf off\n");
+
+	gpio_set_value(trf->en_gpio, 0);
+	gpio_set_value(trf->en2_gpio, 0);
+
+	trf->aborting = false;
+	trf->state = TRF7970A_ST_OFF;
+}
+
+static int trf7970a_switch_rf_on(struct trf7970a *trf)
+{
+	unsigned long delay;
+	int ret;
+
+	dev_dbg(trf->dev, "Switching rf on\n");
+
+	if (trf->powering_up)
+		usleep_range(5000, 6000);
+
+	gpio_set_value(trf->en2_gpio, 1);
+	usleep_range(1000, 2000);
+	gpio_set_value(trf->en_gpio, 1);
+
+	/* The delay between enabling the trf7970a and issuing the first
+	 * command is significantly longer the very first time after powering
+	 * up.  Make sure the longer delay is only done the first time.
+	 */
+	if (trf->powering_up) {
+		delay = 20000;
+		trf->powering_up = false;
+	} else {
+		delay = 5000;
+	}
+
+	usleep_range(delay, delay + 1000);
+
+	ret = trf7970a_init(trf);
+	if (ret)
+		trf7970a_switch_rf_off(trf);
+	else
+		trf->state = TRF7970A_ST_IDLE;
+
+	return ret;
+}
+
+static int trf7970a_switch_rf(struct nfc_digital_dev *ddev, bool on)
+{
+	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);
+	int ret = 0;
+
+	dev_dbg(trf->dev, "Switching RF - state: %d, on: %d\n", trf->state, on);
+
+	mutex_lock(&trf->lock);
+
+	if (on) {
+		switch (trf->state) {
+		case TRF7970A_ST_OFF:
+			ret = trf7970a_switch_rf_on(trf);
+			break;
+		case TRF7970A_ST_IDLE:
+		case TRF7970A_ST_IDLE_RX_BLOCKED:
+			break;
+		default:
+			dev_err(trf->dev, "%s - Invalid request: %d %d\n",
+					__func__, trf->state, on);
+			trf7970a_switch_rf_off(trf);
+		}
+	} else {
+		switch (trf->state) {
+		case TRF7970A_ST_OFF:
+			break;
+		default:
+			dev_err(trf->dev, "%s - Invalid request: %d %d\n",
+					__func__, trf->state, on);
+			/* FALLTHROUGH */
+		case TRF7970A_ST_IDLE:
+		case TRF7970A_ST_IDLE_RX_BLOCKED:
+			trf7970a_switch_rf_off(trf);
+		}
+	}
+
+	mutex_unlock(&trf->lock);
+	return ret;
+}
+
+static int trf7970a_config_rf_tech(struct trf7970a *trf, int tech)
+{
+	int ret = 0;
+
+	dev_dbg(trf->dev, "rf technology: %d\n", tech);
+
+	switch (tech) {
+	case NFC_DIGITAL_RF_TECH_106A:
+		trf->iso_ctrl = TRF7970A_ISO_CTRL_14443A_106;
+		break;
+	default:
+		dev_dbg(trf->dev, "Unsupported rf technology: %d\n", tech);
+		return -EINVAL;
+	}
+
+	trf->technology = tech;
+
+	return ret;
+}
+
+static int trf7970a_config_framing(struct trf7970a *trf, int framing)
+{
+	dev_dbg(trf->dev, "framing: %d\n", framing);
+
+	switch (framing) {
+	case NFC_DIGITAL_FRAMING_NFCA_SHORT:
+	case NFC_DIGITAL_FRAMING_NFCA_STANDARD:
+		trf->tx_cmd = TRF7970A_CMD_TRANSMIT_NO_CRC;
+		trf->iso_ctrl |= TRF7970A_ISO_CTRL_RX_CRC_N;
+		break;
+	case NFC_DIGITAL_FRAMING_NFCA_STANDARD_WITH_CRC_A:
+		trf->tx_cmd = TRF7970A_CMD_TRANSMIT;
+		trf->iso_ctrl &= ~TRF7970A_ISO_CTRL_RX_CRC_N;
+		break;
+	case NFC_DIGITAL_FRAMING_NFCA_T2T:
+		trf->tx_cmd = TRF7970A_CMD_TRANSMIT;
+		trf->iso_ctrl |= TRF7970A_ISO_CTRL_RX_CRC_N;
+		break;
+	default:
+		dev_dbg(trf->dev, "Unsupported Framing: %d\n", framing);
+		return -EINVAL;
+	}
+
+	trf->framing = framing;
+
+	return trf7970a_write(trf, TRF7970A_ISO_CTRL, trf->iso_ctrl);
+}
+
+static int trf7970a_in_configure_hw(struct nfc_digital_dev *ddev, int type,
+		int param)
+{
+	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);
+	int ret = 0;
+
+	dev_dbg(trf->dev, "Configure hw - type: %d, param: %d\n", type, param);
+
+	mutex_lock(&trf->lock);
+
+	if (trf->state == TRF7970A_ST_OFF) {
+		ret = trf7970a_switch_rf_on(trf);
+		if (ret)
+			goto err_out;
+	}
+
+	switch (type) {
+	case NFC_DIGITAL_CONFIG_RF_TECH:
+		ret = trf7970a_config_rf_tech(trf, param);
+		break;
+	case NFC_DIGITAL_CONFIG_FRAMING:
+		ret = trf7970a_config_framing(trf, param);
+		break;
+	default:
+		dev_dbg(trf->dev, "Unknown type: %d\n", type);
+		ret = -EINVAL;
+	}
+
+err_out:
+	mutex_unlock(&trf->lock);
+	return ret;
+}
+
+static int trf7970a_per_cmd_config(struct trf7970a *trf, struct sk_buff *skb)
+{
+	u8 *req = skb->data;
+	u8 special_fcn_reg1;
+	int ret;
+
+	/* When issuing Type 2 read command, make sure the '4_bit_RX' bit in
+	 * special functions register 1 is cleared; otherwise, its a write or
+	 * sector select command and '4_bit_RX' must be set.
+	 */
+	if ((trf->technology == NFC_DIGITAL_RF_TECH_106A) &&
+			(trf->framing == NFC_DIGITAL_FRAMING_NFCA_T2T)) {
+		if (req[0] == NFC_T2T_CMD_READ)
+			special_fcn_reg1 = 0;
+		else
+			special_fcn_reg1 = TRF7970A_SPECIAL_FCN_REG1_4_BIT_RX;
+
+		if (special_fcn_reg1 != trf->special_fcn_reg1) {
+			ret = trf7970a_write(trf, TRF7970A_SPECIAL_FCN_REG1,
+					special_fcn_reg1);
+			if (ret)
+				return ret;
+
+			trf->special_fcn_reg1 = special_fcn_reg1;
+		}
+	}
+
+	return 0;
+}
+
+static int trf7970a_in_send_cmd(struct nfc_digital_dev *ddev,
+		struct sk_buff *skb, u16 timeout,
+		nfc_digital_cmd_complete_t cb, void *arg)
+{
+	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);
+	char *prefix;
+	unsigned int len;
+	int ret;
+
+	dev_dbg(trf->dev, "New request - state: %d, timeout: %d ms, len: %d\n",
+			trf->state, timeout, skb->len);
+
+	if (skb->len > TRF7970A_TX_MAX)
+		return -EINVAL;
+
+	mutex_lock(&trf->lock);
+
+	if ((trf->state != TRF7970A_ST_IDLE) &&
+			(trf->state != TRF7970A_ST_IDLE_RX_BLOCKED)) {
+		dev_err(trf->dev, "%s - Bogus state: %d\n", __func__,
+				trf->state);
+		ret = -EIO;
+		goto out_err;
+	}
+
+	if (trf->aborting) {
+		dev_dbg(trf->dev, "Abort process complete\n");
+		trf->aborting = false;
+		ret = -ECANCELED;
+		goto out_err;
+	}
+
+	trf->rx_skb = nfc_alloc_recv_skb(TRF7970A_RX_SKB_ALLOC_SIZE,
+			GFP_KERNEL);
+	if (!trf->rx_skb) {
+		dev_dbg(trf->dev, "Can't alloc rx_skb\n");
+		ret = -ENOMEM;
+		goto out_err;
+	}
+
+	if (trf->state == TRF7970A_ST_IDLE_RX_BLOCKED) {
+		ret = trf7970a_cmd(trf, TRF7970A_CMD_ENABLE_RX);
+		if (ret)
+			goto out_err;
+
+		trf->state = TRF7970A_ST_IDLE;
+	}
+
+	ret = trf7970a_per_cmd_config(trf, skb);
+	if (ret)
+		goto out_err;
+
+	trf->ddev = ddev;
+	trf->tx_skb = skb;
+	trf->cb = cb;
+	trf->cb_arg = arg;
+	trf->timeout = timeout;
+	trf->ignore_timeout = false;
+
+	len = skb->len;
+	prefix = skb_push(skb, TRF7970A_TX_SKB_HEADROOM);
+
+	/* TX data must be prefixed with a FIFO reset cmd, a cmd that depends
+	 * on what the current framing is, the address of the TX length byte 1
+	 * register (0x1d), and the 2 byte length of the data to be transmitted.
+	 */
+	prefix[0] = TRF7970A_CMD_BIT_CTRL |
+			TRF7970A_CMD_BIT_OPCODE(TRF7970A_CMD_FIFO_RESET);
+	prefix[1] = TRF7970A_CMD_BIT_CTRL |
+			TRF7970A_CMD_BIT_OPCODE(trf->tx_cmd);
+	prefix[2] = TRF7970A_CMD_BIT_CONTINUOUS | TRF7970A_TX_LENGTH_BYTE1;
+
+	if (trf->framing == NFC_DIGITAL_FRAMING_NFCA_SHORT) {
+		prefix[3] = 0x00;
+		prefix[4] = 0x0f; /* 7 bits */
+	} else {
+		prefix[3] = (len & 0xf00) >> 4;
+		prefix[3] |= ((len & 0xf0) >> 4);
+		prefix[4] = ((len & 0x0f) << 4);
+	}
+
+	len = min_t(int, skb->len, TRF7970A_FIFO_SIZE);
+
+	usleep_range(1000, 2000);
+
+	ret = trf7970a_transmit(trf, skb, len);
+	if (ret) {
+		kfree_skb(trf->rx_skb);
+		trf->rx_skb = NULL;
+	}
+
+out_err:
+	mutex_unlock(&trf->lock);
+	return ret;
+}
+
+static int trf7970a_tg_configure_hw(struct nfc_digital_dev *ddev,
+		int type, int param)
+{
+	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);
+
+	dev_dbg(trf->dev, "Unsupported interface\n");
+
+	return -EINVAL;
+}
+
+static int trf7970a_tg_send_cmd(struct nfc_digital_dev *ddev,
+		struct sk_buff *skb, u16 timeout,
+		nfc_digital_cmd_complete_t cb, void *arg)
+{
+	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);
+
+	dev_dbg(trf->dev, "Unsupported interface\n");
+
+	return -EINVAL;
+}
+
+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, "Unsupported interface\n");
+
+	return -EINVAL;
+}
+
+static int trf7970a_tg_listen_mdaa(struct nfc_digital_dev *ddev,
+		struct digital_tg_mdaa_params *mdaa_params,
+		u16 timeout, nfc_digital_cmd_complete_t cb, void *arg)
+{
+	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);
+
+	dev_dbg(trf->dev, "Unsupported interface\n");
+
+	return -EINVAL;
+}
+
+static void trf7970a_abort_cmd(struct nfc_digital_dev *ddev)
+{
+	struct trf7970a *trf = nfc_digital_get_drvdata(ddev);
+
+	dev_dbg(trf->dev, "Abort process initiated\n");
+
+	mutex_lock(&trf->lock);
+	trf->aborting = true;
+	mutex_unlock(&trf->lock);
+}
+
+static struct nfc_digital_ops trf7970a_nfc_ops = {
+	.in_configure_hw	= trf7970a_in_configure_hw,
+	.in_send_cmd		= trf7970a_in_send_cmd,
+	.tg_configure_hw	= trf7970a_tg_configure_hw,
+	.tg_send_cmd		= trf7970a_tg_send_cmd,
+	.tg_listen		= trf7970a_tg_listen,
+	.tg_listen_mdaa		= trf7970a_tg_listen_mdaa,
+	.switch_rf		= trf7970a_switch_rf,
+	.abort_cmd		= trf7970a_abort_cmd,
+};
+
+static int trf7970a_probe(struct spi_device *spi)
+{
+	struct device_node *np = spi->dev.of_node;
+	const struct spi_device_id *id = spi_get_device_id(spi);
+	struct trf7970a *trf;
+	int ret;
+
+	if (!np) {
+		dev_err(&spi->dev, "No Device Tree entry\n");
+		return -EINVAL;
+	}
+
+	trf = devm_kzalloc(&spi->dev, sizeof(*trf), GFP_KERNEL);
+	if (!trf)
+		return -ENOMEM;
+
+	trf->state = TRF7970A_ST_OFF;
+	trf->dev = &spi->dev;
+	trf->spi = spi;
+	trf->quirks = id->driver_data;
+
+	spi->mode = SPI_MODE_1;
+	spi->bits_per_word = 8;
+
+	/* There are two enable pins - both must be present */
+	trf->en_gpio = of_get_named_gpio(np, "ti,enable-gpios", 0);
+	if (!gpio_is_valid(trf->en_gpio)) {
+		dev_err(trf->dev, "No EN GPIO property\n");
+		return trf->en_gpio;
+	}
+
+	ret = devm_gpio_request_one(trf->dev, trf->en_gpio,
+			GPIOF_DIR_OUT | GPIOF_INIT_LOW, "EN");
+	if (ret) {
+		dev_err(trf->dev, "Can't request EN GPIO: %d\n", ret);
+		return ret;
+	}
+
+	trf->en2_gpio = of_get_named_gpio(np, "ti,enable-gpios", 1);
+	if (!gpio_is_valid(trf->en2_gpio)) {
+		dev_err(trf->dev, "No EN2 GPIO property\n");
+		return trf->en2_gpio;
+	}
+
+	ret = devm_gpio_request_one(trf->dev, trf->en2_gpio,
+			GPIOF_DIR_OUT | GPIOF_INIT_LOW, "EN2");
+	if (ret) {
+		dev_err(trf->dev, "Can't request EN2 GPIO: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_request_threaded_irq(trf->dev, spi->irq, NULL,
+			trf7970a_irq, IRQF_TRIGGER_RISING | IRQF_ONESHOT,
+			"trf7970a", trf);
+	if (ret) {
+		dev_err(trf->dev, "Can't request IRQ#%d: %d\n", spi->irq, ret);
+		return ret;
+	}
+
+	mutex_init(&trf->lock);
+	INIT_DELAYED_WORK(&trf->timeout_work, trf7970a_timeout_work_handler);
+
+	trf->regulator = devm_regulator_get(&spi->dev, "vin");
+	if (IS_ERR(trf->regulator)) {
+		ret = PTR_ERR(trf->regulator);
+		dev_err(trf->dev, "Can't get VIN regulator: %d\n", ret);
+		goto err_destroy_lock;
+	}
+
+	ret = regulator_enable(trf->regulator);
+	if (ret) {
+		dev_err(trf->dev, "Can't enable VIN: %d\n", ret);
+		goto err_destroy_lock;
+	}
+
+	trf->powering_up = true;
+
+	trf->ddev = nfc_digital_allocate_device(&trf7970a_nfc_ops,
+			TRF7970A_SUPPORTED_PROTOCOLS,
+			NFC_DIGITAL_DRV_CAPS_IN_CRC, TRF7970A_TX_SKB_HEADROOM,
+			0);
+	if (!trf->ddev) {
+		dev_err(trf->dev, "Can't allocate NFC digital device\n");
+		ret = -ENOMEM;
+		goto err_disable_regulator;
+	}
+
+	nfc_digital_set_parent_dev(trf->ddev, trf->dev);
+	nfc_digital_set_drvdata(trf->ddev, trf);
+	spi_set_drvdata(spi, trf);
+
+	ret = nfc_digital_register_device(trf->ddev);
+	if (ret) {
+		dev_err(trf->dev, "Can't register NFC digital device: %d\n",
+				ret);
+		goto err_free_ddev;
+	}
+
+	return 0;
+
+err_free_ddev:
+	nfc_digital_free_device(trf->ddev);
+err_disable_regulator:
+	regulator_disable(trf->regulator);
+err_destroy_lock:
+	mutex_destroy(&trf->lock);
+	return ret;
+}
+
+static int trf7970a_remove(struct spi_device *spi)
+{
+	struct trf7970a *trf = spi_get_drvdata(spi);
+
+	mutex_lock(&trf->lock);
+
+	trf7970a_switch_rf_off(trf);
+	trf7970a_init(trf);
+
+	switch (trf->state) {
+	case TRF7970A_ST_WAIT_FOR_TX_FIFO:
+	case TRF7970A_ST_WAIT_FOR_RX_DATA:
+	case TRF7970A_ST_WAIT_FOR_RX_DATA_CONT:
+		trf7970a_send_err_upstream(trf, -ECANCELED);
+		break;
+	default:
+		break;
+	}
+
+	mutex_unlock(&trf->lock);
+
+	nfc_digital_unregister_device(trf->ddev);
+	nfc_digital_free_device(trf->ddev);
+
+	regulator_disable(trf->regulator);
+
+	mutex_destroy(&trf->lock);
+
+	return 0;
+}
+
+static const struct spi_device_id trf7970a_id_table[] = {
+	{ "trf7970a", TRF7970A_QUIRK_IRQ_STATUS_READ_ERRATA },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, trf7970a_id_table);
+
+static struct spi_driver trf7970a_spi_driver = {
+	.probe		= trf7970a_probe,
+	.remove		= trf7970a_remove,
+	.id_table	= trf7970a_id_table,
+	.driver		= {
+		.name	= "trf7970a",
+		.owner	= THIS_MODULE,
+	},
+};
+
+module_spi_driver(trf7970a_spi_driver);
+
+MODULE_AUTHOR("Mark A. Greer <mgreer@animalcreek.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("TI trf7970a RFID/NFC Transceiver Driver");