NFC: trf7970a: Add driver with ISO/IEC 14443 Type 2 Tag Support
authorMark A. Greer <mgreer@animalcreek.com>
Mon, 10 Mar 2014 18:56:22 +0000 (11:56 -0700)
committerSamuel Ortiz <sameo@linux.intel.com>
Mon, 10 Mar 2014 23:46:55 +0000 (00:46 +0100)
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>
drivers/nfc/Kconfig
drivers/nfc/Makefile
drivers/nfc/trf7970a.c [new file with mode: 0644]

index fe20e1cc0545bf4bb9700f054bddea12fb1ec643..65d4ca19d1328ec737c68684c30de01fc8347b8d 100644 (file)
@@ -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
index 56ab822ba03d9f1be61a544f975368de086b75ba..ae42a3fa60c981b965bbb0cdb004b7c3c591d01d 100644 (file)
@@ -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 (file)
index 0000000..0d62d45
--- /dev/null
@@ -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");