NFC: Use communicate thru only for PaSoRi when trying to read Felica tags

[linux.git] / drivers / nfc / pn544_hci.c

/*
 * HCI based Driver for NXP PN544 NFC Chip
 *
 * Copyright (C) 2012  Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the
 * Free Software Foundation, Inc.,
 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include <linux/crc-ccitt.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/miscdevice.h>
#include <linux/interrupt.h>
#include <linux/gpio.h>
#include <linux/i2c.h>

#include <linux/nfc.h>
#include <net/nfc/hci.h>
#include <net/nfc/shdlc.h>

#include <linux/nfc/pn544.h>

#define DRIVER_DESC "HCI NFC driver for PN544"

#define PN544_HCI_DRIVER_NAME "pn544_hci"

/* Timing restrictions (ms) */
#define PN544_HCI_RESETVEN_TIME		30

static struct i2c_device_id pn544_hci_id_table[] = {
	{"pn544", 0},
	{}
};

MODULE_DEVICE_TABLE(i2c, pn544_hci_id_table);

#define HCI_MODE 0
#define FW_MODE 1

/* framing in HCI mode */
#define PN544_HCI_LLC_LEN		1
#define PN544_HCI_LLC_CRC		2
#define PN544_HCI_LLC_LEN_CRC		(PN544_HCI_LLC_LEN + PN544_HCI_LLC_CRC)
#define PN544_HCI_LLC_MIN_SIZE		(1 + PN544_HCI_LLC_LEN_CRC)
#define PN544_HCI_LLC_MAX_PAYLOAD	29
#define PN544_HCI_LLC_MAX_SIZE		(PN544_HCI_LLC_LEN_CRC + 1 + \
					 PN544_HCI_LLC_MAX_PAYLOAD)

enum pn544_state {
	PN544_ST_COLD,
	PN544_ST_FW_READY,
	PN544_ST_READY,
};

#define FULL_VERSION_LEN 11

/* Proprietary commands */
#define PN544_WRITE		0x3f

/* Proprietary gates, events, commands and registers */

/* NFC_HCI_RF_READER_A_GATE additional registers and commands */
#define PN544_RF_READER_A_AUTO_ACTIVATION			0x10
#define PN544_RF_READER_A_CMD_CONTINUE_ACTIVATION		0x12
#define PN544_MIFARE_CMD					0x21

/* Commands that apply to all RF readers */
#define PN544_RF_READER_CMD_PRESENCE_CHECK	0x30
#define PN544_RF_READER_CMD_ACTIVATE_NEXT	0x32

/* NFC_HCI_ID_MGMT_GATE additional registers */
#define PN544_ID_MGMT_FULL_VERSION_SW		0x10

#define PN544_RF_READER_ISO15693_GATE		0x12

#define PN544_RF_READER_F_GATE			0x14
#define PN544_FELICA_ID				0x04
#define PN544_FELICA_RAW			0x20

#define PN544_RF_READER_JEWEL_GATE		0x15
#define PN544_JEWEL_RAW_CMD			0x23

#define PN544_RF_READER_NFCIP1_INITIATOR_GATE	0x30
#define PN544_RF_READER_NFCIP1_TARGET_GATE	0x31

#define PN544_SYS_MGMT_GATE			0x90
#define PN544_SYS_MGMT_INFO_NOTIFICATION	0x02

#define PN544_POLLING_LOOP_MGMT_GATE		0x94
#define PN544_PL_RDPHASES			0x06
#define PN544_PL_EMULATION			0x07
#define PN544_PL_NFCT_DEACTIVATED		0x09

#define PN544_SWP_MGMT_GATE			0xA0

#define PN544_NFC_WI_MGMT_GATE			0xA1

static struct nfc_hci_gate pn544_gates[] = {
	{NFC_HCI_ADMIN_GATE, NFC_HCI_INVALID_PIPE},
	{NFC_HCI_LOOPBACK_GATE, NFC_HCI_INVALID_PIPE},
	{NFC_HCI_ID_MGMT_GATE, NFC_HCI_INVALID_PIPE},
	{NFC_HCI_LINK_MGMT_GATE, NFC_HCI_INVALID_PIPE},
	{NFC_HCI_RF_READER_B_GATE, NFC_HCI_INVALID_PIPE},
	{NFC_HCI_RF_READER_A_GATE, NFC_HCI_INVALID_PIPE},
	{PN544_SYS_MGMT_GATE, NFC_HCI_INVALID_PIPE},
	{PN544_SWP_MGMT_GATE, NFC_HCI_INVALID_PIPE},
	{PN544_POLLING_LOOP_MGMT_GATE, NFC_HCI_INVALID_PIPE},
	{PN544_NFC_WI_MGMT_GATE, NFC_HCI_INVALID_PIPE},
	{PN544_RF_READER_F_GATE, NFC_HCI_INVALID_PIPE},
	{PN544_RF_READER_JEWEL_GATE, NFC_HCI_INVALID_PIPE},
	{PN544_RF_READER_ISO15693_GATE, NFC_HCI_INVALID_PIPE},
	{PN544_RF_READER_NFCIP1_INITIATOR_GATE, NFC_HCI_INVALID_PIPE},
	{PN544_RF_READER_NFCIP1_TARGET_GATE, NFC_HCI_INVALID_PIPE}
};

/* Largest headroom needed for outgoing custom commands */
#define PN544_CMDS_HEADROOM	2

struct pn544_hci_info {
	struct i2c_client *i2c_dev;
	struct nfc_shdlc *shdlc;

	enum pn544_state state;

	struct mutex info_lock;

	unsigned int gpio_en;
	unsigned int gpio_irq;
	unsigned int gpio_fw;
	unsigned int en_polarity;

	int hard_fault;		/*
				 * < 0 if hardware error occured (e.g. i2c err)
				 * and prevents normal operation.
				 */
};

static void pn544_hci_platform_init(struct pn544_hci_info *info)
{
	int polarity, retry, ret;
	char rset_cmd[] = { 0x05, 0xF9, 0x04, 0x00, 0xC3, 0xE5 };
	int count = sizeof(rset_cmd);

	pr_info(DRIVER_DESC ": %s\n", __func__);
	dev_info(&info->i2c_dev->dev, "Detecting nfc_en polarity\n");

	/* Disable fw download */
	gpio_set_value(info->gpio_fw, 0);

	for (polarity = 0; polarity < 2; polarity++) {
		info->en_polarity = polarity;
		retry = 3;
		while (retry--) {
			/* power off */
			gpio_set_value(info->gpio_en, !info->en_polarity);
			usleep_range(10000, 15000);

			/* power on */
			gpio_set_value(info->gpio_en, info->en_polarity);
			usleep_range(10000, 15000);

			/* send reset */
			dev_dbg(&info->i2c_dev->dev, "Sending reset cmd\n");
			ret = i2c_master_send(info->i2c_dev, rset_cmd, count);
			if (ret == count) {
				dev_info(&info->i2c_dev->dev,
					 "nfc_en polarity : active %s\n",
					 (polarity == 0 ? "low" : "high"));
				goto out;
			}
		}
	}

	dev_err(&info->i2c_dev->dev,
		"Could not detect nfc_en polarity, fallback to active high\n");

out:
	gpio_set_value(info->gpio_en, !info->en_polarity);
}

static int pn544_hci_enable(struct pn544_hci_info *info, int mode)
{
	pr_info(DRIVER_DESC ": %s\n", __func__);

	gpio_set_value(info->gpio_fw, 0);
	gpio_set_value(info->gpio_en, info->en_polarity);
	usleep_range(10000, 15000);

	return 0;
}

static void pn544_hci_disable(struct pn544_hci_info *info)
{
	pr_info(DRIVER_DESC ": %s\n", __func__);

	gpio_set_value(info->gpio_fw, 0);
	gpio_set_value(info->gpio_en, !info->en_polarity);
	usleep_range(10000, 15000);

	gpio_set_value(info->gpio_en, info->en_polarity);
	usleep_range(10000, 15000);

	gpio_set_value(info->gpio_en, !info->en_polarity);
	usleep_range(10000, 15000);
}

static int pn544_hci_i2c_write(struct i2c_client *client, u8 *buf, int len)
{
	int r;

	usleep_range(3000, 6000);

	r = i2c_master_send(client, buf, len);

	if (r == -EREMOTEIO) {	/* Retry, chip was in standby */
		usleep_range(6000, 10000);
		r = i2c_master_send(client, buf, len);
	}

	if (r >= 0 && r != len)
		r = -EREMOTEIO;

	return r;
}

static int check_crc(u8 *buf, int buflen)
{
	int len;
	u16 crc;

	len = buf[0] + 1;
	crc = crc_ccitt(0xffff, buf, len - 2);
	crc = ~crc;

	if (buf[len - 2] != (crc & 0xff) || buf[len - 1] != (crc >> 8)) {
		pr_err(PN544_HCI_DRIVER_NAME ": CRC error 0x%x != 0x%x 0x%x\n",
		       crc, buf[len - 1], buf[len - 2]);

		pr_info(DRIVER_DESC ": %s : BAD CRC\n", __func__);
		print_hex_dump(KERN_DEBUG, "crc: ", DUMP_PREFIX_NONE,
			       16, 2, buf, buflen, false);
		return -EPERM;
	}
	return 0;
}

/*
 * Reads an shdlc frame and returns it in a newly allocated sk_buff. Guarantees
 * that i2c bus will be flushed and that next read will start on a new frame.
 * returned skb contains only LLC header and payload.
 * returns:
 * -EREMOTEIO : i2c read error (fatal)
 * -EBADMSG : frame was incorrect and discarded
 * -ENOMEM : cannot allocate skb, frame dropped
 */
static int pn544_hci_i2c_read(struct i2c_client *client, struct sk_buff **skb)
{
	int r;
	u8 len;
	u8 tmp[PN544_HCI_LLC_MAX_SIZE - 1];

	r = i2c_master_recv(client, &len, 1);
	if (r != 1) {
		dev_err(&client->dev, "cannot read len byte\n");
		return -EREMOTEIO;
	}

	if ((len < (PN544_HCI_LLC_MIN_SIZE - 1)) ||
	    (len > (PN544_HCI_LLC_MAX_SIZE - 1))) {
		dev_err(&client->dev, "invalid len byte\n");
		r = -EBADMSG;
		goto flush;
	}

	*skb = alloc_skb(1 + len, GFP_KERNEL);
	if (*skb == NULL) {
		r = -ENOMEM;
		goto flush;
	}

	*skb_put(*skb, 1) = len;

	r = i2c_master_recv(client, skb_put(*skb, len), len);
	if (r != len) {
		kfree_skb(*skb);
		return -EREMOTEIO;
	}

	r = check_crc((*skb)->data, (*skb)->len);
	if (r != 0) {
		kfree_skb(*skb);
		r = -EBADMSG;
		goto flush;
	}

	skb_pull(*skb, 1);
	skb_trim(*skb, (*skb)->len - 2);

	usleep_range(3000, 6000);

	return 0;

flush:
	if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0)
		r = -EREMOTEIO;

	usleep_range(3000, 6000);

	return r;
}

/*
 * Reads an shdlc frame from the chip. This is not as straightforward as it
 * seems. There are cases where we could loose the frame start synchronization.
 * The frame format is len-data-crc, and corruption can occur anywhere while
 * transiting on i2c bus, such that we could read an invalid len.
 * In order to recover synchronization with the next frame, we must be sure
 * to read the real amount of data without using the len byte. We do this by
 * assuming the following:
 * - the chip will always present only one single complete frame on the bus
 *   before triggering the interrupt
 * - the chip will not present a new frame until we have completely read
 *   the previous one (or until we have handled the interrupt).
 * The tricky case is when we read a corrupted len that is less than the real
 * len. We must detect this here in order to determine that we need to flush
 * the bus. This is the reason why we check the crc here.
 */
static irqreturn_t pn544_hci_irq_thread_fn(int irq, void *dev_id)
{
	struct pn544_hci_info *info = dev_id;
	struct i2c_client *client = info->i2c_dev;
	struct sk_buff *skb = NULL;
	int r;

	BUG_ON(!info);
	BUG_ON(irq != info->i2c_dev->irq);

	dev_dbg(&client->dev, "IRQ\n");

	if (info->hard_fault != 0)
		return IRQ_HANDLED;

	r = pn544_hci_i2c_read(client, &skb);
	if (r == -EREMOTEIO) {
		info->hard_fault = r;

		nfc_shdlc_recv_frame(info->shdlc, NULL);

		return IRQ_HANDLED;
	} else if ((r == -ENOMEM) || (r == -EBADMSG)) {
		return IRQ_HANDLED;
	}

	nfc_shdlc_recv_frame(info->shdlc, skb);

	return IRQ_HANDLED;
}

static int pn544_hci_open(struct nfc_shdlc *shdlc)
{
	struct pn544_hci_info *info = nfc_shdlc_get_clientdata(shdlc);
	int r = 0;

	mutex_lock(&info->info_lock);

	if (info->state != PN544_ST_COLD) {
		r = -EBUSY;
		goto out;
	}

	r = pn544_hci_enable(info, HCI_MODE);

	if (r == 0)
		info->state = PN544_ST_READY;

out:
	mutex_unlock(&info->info_lock);
	return r;
}

static void pn544_hci_close(struct nfc_shdlc *shdlc)
{
	struct pn544_hci_info *info = nfc_shdlc_get_clientdata(shdlc);

	mutex_lock(&info->info_lock);

	if (info->state == PN544_ST_COLD)
		goto out;

	pn544_hci_disable(info);

	info->state = PN544_ST_COLD;

out:
	mutex_unlock(&info->info_lock);
}

static int pn544_hci_ready(struct nfc_shdlc *shdlc)
{
	struct nfc_hci_dev *hdev = nfc_shdlc_get_hci_dev(shdlc);
	struct sk_buff *skb;
	static struct hw_config {
		u8 adr[2];
		u8 value;
	} hw_config[] = {
		{{0x9f, 0x9a}, 0x00},

		{{0x98, 0x10}, 0xbc},

		{{0x9e, 0x71}, 0x00},

		{{0x98, 0x09}, 0x00},

		{{0x9e, 0xb4}, 0x00},

		{{0x9e, 0xd9}, 0xff},
		{{0x9e, 0xda}, 0xff},
		{{0x9e, 0xdb}, 0x23},
		{{0x9e, 0xdc}, 0x21},
		{{0x9e, 0xdd}, 0x22},
		{{0x9e, 0xde}, 0x24},

		{{0x9c, 0x01}, 0x08},

		{{0x9e, 0xaa}, 0x01},

		{{0x9b, 0xd1}, 0x0d},
		{{0x9b, 0xd2}, 0x24},
		{{0x9b, 0xd3}, 0x0a},
		{{0x9b, 0xd4}, 0x22},
		{{0x9b, 0xd5}, 0x08},
		{{0x9b, 0xd6}, 0x1e},
		{{0x9b, 0xdd}, 0x1c},

		{{0x9b, 0x84}, 0x13},
		{{0x99, 0x81}, 0x7f},
		{{0x99, 0x31}, 0x70},

		{{0x98, 0x00}, 0x3f},

		{{0x9f, 0x09}, 0x00},

		{{0x9f, 0x0a}, 0x05},

		{{0x9e, 0xd1}, 0xa1},
		{{0x99, 0x23}, 0x00},

		{{0x9e, 0x74}, 0x80},

		{{0x9f, 0x28}, 0x10},

		{{0x9f, 0x35}, 0x14},

		{{0x9f, 0x36}, 0x60},

		{{0x9c, 0x31}, 0x00},

		{{0x9c, 0x32}, 0xc8},

		{{0x9c, 0x19}, 0x40},

		{{0x9c, 0x1a}, 0x40},

		{{0x9c, 0x0c}, 0x00},

		{{0x9c, 0x0d}, 0x00},

		{{0x9c, 0x12}, 0x00},

		{{0x9c, 0x13}, 0x00},

		{{0x98, 0xa2}, 0x0e},

		{{0x98, 0x93}, 0x40},

		{{0x98, 0x7d}, 0x02},
		{{0x98, 0x7e}, 0x00},
		{{0x9f, 0xc8}, 0x01},
	};
	struct hw_config *p = hw_config;
	int count = ARRAY_SIZE(hw_config);
	struct sk_buff *res_skb;
	u8 param[4];
	int r;

	param[0] = 0;
	while (count--) {
		param[1] = p->adr[0];
		param[2] = p->adr[1];
		param[3] = p->value;

		r = nfc_hci_send_cmd(hdev, PN544_SYS_MGMT_GATE, PN544_WRITE,
				     param, 4, &res_skb);
		if (r < 0)
			return r;

		if (res_skb->len != 1) {
			kfree_skb(res_skb);
			return -EPROTO;
		}

		if (res_skb->data[0] != p->value) {
			kfree_skb(res_skb);
			return -EIO;
		}

		kfree_skb(res_skb);

		p++;
	}

	param[0] = NFC_HCI_UICC_HOST_ID;
	r = nfc_hci_set_param(hdev, NFC_HCI_ADMIN_GATE,
			      NFC_HCI_ADMIN_WHITELIST, param, 1);
	if (r < 0)
		return r;

	param[0] = 0x3d;
	r = nfc_hci_set_param(hdev, PN544_SYS_MGMT_GATE,
			      PN544_SYS_MGMT_INFO_NOTIFICATION, param, 1);
	if (r < 0)
		return r;

	param[0] = 0x0;
	r = nfc_hci_set_param(hdev, NFC_HCI_RF_READER_A_GATE,
			      PN544_RF_READER_A_AUTO_ACTIVATION, param, 1);
	if (r < 0)
		return r;

	r = nfc_hci_send_event(hdev, NFC_HCI_RF_READER_A_GATE,
			       NFC_HCI_EVT_END_OPERATION, NULL, 0);
	if (r < 0)
		return r;

	param[0] = 0x1;
	r = nfc_hci_set_param(hdev, PN544_POLLING_LOOP_MGMT_GATE,
			      PN544_PL_NFCT_DEACTIVATED, param, 1);
	if (r < 0)
		return r;

	param[0] = 0x0;
	r = nfc_hci_set_param(hdev, PN544_POLLING_LOOP_MGMT_GATE,
			      PN544_PL_RDPHASES, param, 1);
	if (r < 0)
		return r;

	r = nfc_hci_get_param(hdev, NFC_HCI_ID_MGMT_GATE,
			      PN544_ID_MGMT_FULL_VERSION_SW, &skb);
	if (r < 0)
		return r;

	if (skb->len != FULL_VERSION_LEN) {
		kfree_skb(skb);
		return -EINVAL;
	}

	print_hex_dump(KERN_DEBUG, "FULL VERSION SOFTWARE INFO: ",
		       DUMP_PREFIX_NONE, 16, 1,
		       skb->data, FULL_VERSION_LEN, false);

	kfree_skb(skb);

	return 0;
}

static int pn544_hci_xmit(struct nfc_shdlc *shdlc, struct sk_buff *skb)
{
	struct pn544_hci_info *info = nfc_shdlc_get_clientdata(shdlc);
	struct i2c_client *client = info->i2c_dev;

	if (info->hard_fault != 0)
		return info->hard_fault;

	return pn544_hci_i2c_write(client, skb->data, skb->len);
}

static int pn544_hci_start_poll(struct nfc_shdlc *shdlc,
				u32 im_protocols, u32 tm_protocols)
{
	struct nfc_hci_dev *hdev = nfc_shdlc_get_hci_dev(shdlc);
	u8 phases = 0;
	int r;
	u8 duration[2];
	u8 activated;

	pr_info(DRIVER_DESC ": %s protocols 0x%x 0x%x\n",
		__func__, im_protocols, tm_protocols);

	r = nfc_hci_send_event(hdev, NFC_HCI_RF_READER_A_GATE,
			       NFC_HCI_EVT_END_OPERATION, NULL, 0);
	if (r < 0)
		return r;

	duration[0] = 0x18;
	duration[1] = 0x6a;
	r = nfc_hci_set_param(hdev, PN544_POLLING_LOOP_MGMT_GATE,
			      PN544_PL_EMULATION, duration, 2);
	if (r < 0)
		return r;

	activated = 0;
	r = nfc_hci_set_param(hdev, PN544_POLLING_LOOP_MGMT_GATE,
			      PN544_PL_NFCT_DEACTIVATED, &activated, 1);
	if (r < 0)
		return r;

	if (im_protocols & (NFC_PROTO_ISO14443_MASK | NFC_PROTO_MIFARE_MASK |
			 NFC_PROTO_JEWEL_MASK))
		phases |= 1;		/* Type A */
	if (im_protocols & NFC_PROTO_FELICA_MASK) {
		phases |= (1 << 2);	/* Type F 212 */
		phases |= (1 << 3);	/* Type F 424 */
	}

	phases |= (1 << 5);		/* NFC active */

	r = nfc_hci_set_param(hdev, PN544_POLLING_LOOP_MGMT_GATE,
			      PN544_PL_RDPHASES, &phases, 1);
	if (r < 0)
		return r;

	r = nfc_hci_send_event(hdev, NFC_HCI_RF_READER_A_GATE,
			       NFC_HCI_EVT_READER_REQUESTED, NULL, 0);
	if (r < 0)
		nfc_hci_send_event(hdev, NFC_HCI_RF_READER_A_GATE,
				   NFC_HCI_EVT_END_OPERATION, NULL, 0);

	return r;
}

static int pn544_hci_target_from_gate(struct nfc_shdlc *shdlc, u8 gate,
				      struct nfc_target *target)
{
	switch (gate) {
	case PN544_RF_READER_F_GATE:
		target->supported_protocols = NFC_PROTO_FELICA_MASK;
		break;
	case PN544_RF_READER_JEWEL_GATE:
		target->supported_protocols = NFC_PROTO_JEWEL_MASK;
		target->sens_res = 0x0c00;
		break;
	default:
		return -EPROTO;
	}

	return 0;
}

static int pn544_hci_complete_target_discovered(struct nfc_shdlc *shdlc,
						u8 gate,
						struct nfc_target *target)
{
	struct nfc_hci_dev *hdev = nfc_shdlc_get_hci_dev(shdlc);
	struct sk_buff *uid_skb;
	int r = 0;

	if (target->supported_protocols & NFC_PROTO_MIFARE_MASK) {
		if (target->nfcid1_len != 4 && target->nfcid1_len != 7 &&
		    target->nfcid1_len != 10)
			return -EPROTO;

		r = nfc_hci_send_cmd(hdev, NFC_HCI_RF_READER_A_GATE,
				     PN544_RF_READER_CMD_ACTIVATE_NEXT,
				     target->nfcid1, target->nfcid1_len, NULL);
	} else if (target->supported_protocols & NFC_PROTO_FELICA_MASK) {
		r = nfc_hci_get_param(hdev, PN544_RF_READER_F_GATE,
				      PN544_FELICA_ID, &uid_skb);
		if (r < 0)
			return r;

		if (uid_skb->len != 8) {
			kfree_skb(uid_skb);
			return -EPROTO;
		}

		r = nfc_hci_send_cmd(hdev, PN544_RF_READER_F_GATE,
				     PN544_RF_READER_CMD_ACTIVATE_NEXT,
				     uid_skb->data, uid_skb->len, NULL);
		kfree_skb(uid_skb);
	} else if (target->supported_protocols & NFC_PROTO_ISO14443_MASK) {
		/*
		 * TODO: maybe other ISO 14443 require some kind of continue
		 * activation, but for now we've seen only this one below.
		 */
		if (target->sens_res == 0x4403)	/* Type 4 Mifare DESFire */
			r = nfc_hci_send_cmd(hdev, NFC_HCI_RF_READER_A_GATE,
			      PN544_RF_READER_A_CMD_CONTINUE_ACTIVATION,
			      NULL, 0, NULL);
	}

	return r;
}

#define MIFARE_CMD_AUTH_KEY_A	0x60
#define MIFARE_CMD_AUTH_KEY_B	0x61
#define MIFARE_CMD_HEADER	2
#define MIFARE_UID_LEN		4
#define MIFARE_KEY_LEN		6
#define MIFARE_CMD_LEN		12
/*
 * Returns:
 * <= 0: driver handled the data exchange
 *    1: driver doesn't especially handle, please do standard processing
 */
static int pn544_hci_data_exchange(struct nfc_shdlc *shdlc,
				   struct nfc_target *target,
				   struct sk_buff *skb,
				   struct sk_buff **res_skb)
{
	struct nfc_hci_dev *hdev = nfc_shdlc_get_hci_dev(shdlc);
	int r;

	pr_info(DRIVER_DESC ": %s for gate=%d\n", __func__,
		target->hci_reader_gate);

	switch (target->hci_reader_gate) {
	case NFC_HCI_RF_READER_A_GATE:
		if (target->supported_protocols & NFC_PROTO_MIFARE_MASK) {
			/*
			 * It seems that pn544 is inverting key and UID for
			 * MIFARE authentication commands.
			 */
			if (skb->len == MIFARE_CMD_LEN &&
			    (skb->data[0] == MIFARE_CMD_AUTH_KEY_A ||
			     skb->data[0] == MIFARE_CMD_AUTH_KEY_B)) {
				u8 uid[MIFARE_UID_LEN];
				u8 *data = skb->data + MIFARE_CMD_HEADER;

				memcpy(uid, data + MIFARE_KEY_LEN,
				       MIFARE_UID_LEN);
				memmove(data + MIFARE_UID_LEN, data,
					MIFARE_KEY_LEN);
				memcpy(data, uid, MIFARE_UID_LEN);
			}

			return nfc_hci_send_cmd(hdev, target->hci_reader_gate,
						PN544_MIFARE_CMD,
						skb->data, skb->len, res_skb);
		} else
			return 1;
	case PN544_RF_READER_F_GATE:
		*skb_push(skb, 1) = 0;
		*skb_push(skb, 1) = 0;

		r = nfc_hci_send_cmd(hdev, target->hci_reader_gate,
				     PN544_FELICA_RAW,
				     skb->data, skb->len, res_skb);
		if (r == 0)
			skb_pull(*res_skb, 1);
		return r;
	case PN544_RF_READER_JEWEL_GATE:
		return nfc_hci_send_cmd(hdev, target->hci_reader_gate,
					PN544_JEWEL_RAW_CMD,
					skb->data, skb->len, res_skb);
	default:
		return 1;
	}
}

static int pn544_hci_check_presence(struct nfc_shdlc *shdlc,
				   struct nfc_target *target)
{
	struct nfc_hci_dev *hdev = nfc_shdlc_get_hci_dev(shdlc);

	return nfc_hci_send_cmd(hdev, target->hci_reader_gate,
				PN544_RF_READER_CMD_PRESENCE_CHECK,
				NULL, 0, NULL);
}

static struct nfc_shdlc_ops pn544_shdlc_ops = {
	.open = pn544_hci_open,
	.close = pn544_hci_close,
	.hci_ready = pn544_hci_ready,
	.xmit = pn544_hci_xmit,
	.start_poll = pn544_hci_start_poll,
	.target_from_gate = pn544_hci_target_from_gate,
	.complete_target_discovered = pn544_hci_complete_target_discovered,
	.data_exchange = pn544_hci_data_exchange,
	.check_presence = pn544_hci_check_presence,
};

static int __devinit pn544_hci_probe(struct i2c_client *client,
				     const struct i2c_device_id *id)
{
	struct pn544_hci_info *info;
	struct pn544_nfc_platform_data *pdata;
	int r = 0;
	u32 protocols;
	struct nfc_hci_init_data init_data;

	dev_dbg(&client->dev, "%s\n", __func__);
	dev_dbg(&client->dev, "IRQ: %d\n", client->irq);

	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
		dev_err(&client->dev, "Need I2C_FUNC_I2C\n");
		return -ENODEV;
	}

	info = kzalloc(sizeof(struct pn544_hci_info), GFP_KERNEL);
	if (!info) {
		dev_err(&client->dev,
			"Cannot allocate memory for pn544_hci_info.\n");
		r = -ENOMEM;
		goto err_info_alloc;
	}

	info->i2c_dev = client;
	info->state = PN544_ST_COLD;
	mutex_init(&info->info_lock);
	i2c_set_clientdata(client, info);

	pdata = client->dev.platform_data;
	if (pdata == NULL) {
		dev_err(&client->dev, "No platform data\n");
		r = -EINVAL;
		goto err_pdata;
	}

	if (pdata->request_resources == NULL) {
		dev_err(&client->dev, "request_resources() missing\n");
		r = -EINVAL;
		goto err_pdata;
	}

	r = pdata->request_resources(client);
	if (r) {
		dev_err(&client->dev, "Cannot get platform resources\n");
		goto err_pdata;
	}

	info->gpio_en = pdata->get_gpio(NFC_GPIO_ENABLE);
	info->gpio_fw = pdata->get_gpio(NFC_GPIO_FW_RESET);
	info->gpio_irq = pdata->get_gpio(NFC_GPIO_IRQ);

	pn544_hci_platform_init(info);

	r = request_threaded_irq(client->irq, NULL, pn544_hci_irq_thread_fn,
				 IRQF_TRIGGER_RISING, PN544_HCI_DRIVER_NAME,
				 info);
	if (r < 0) {
		dev_err(&client->dev, "Unable to register IRQ handler\n");
		goto err_rti;
	}

	init_data.gate_count = ARRAY_SIZE(pn544_gates);

	memcpy(init_data.gates, pn544_gates, sizeof(pn544_gates));

	/*
	 * TODO: Session id must include the driver name + some bus addr
	 * persistent info to discriminate 2 identical chips
	 */
	strcpy(init_data.session_id, "ID544HCI");

	protocols = NFC_PROTO_JEWEL_MASK |
		    NFC_PROTO_MIFARE_MASK |
		    NFC_PROTO_FELICA_MASK |
		    NFC_PROTO_ISO14443_MASK |
		    NFC_PROTO_NFC_DEP_MASK;

	info->shdlc = nfc_shdlc_allocate(&pn544_shdlc_ops,
					 &init_data, protocols,
					 PN544_CMDS_HEADROOM, 0,
					 PN544_HCI_LLC_MAX_PAYLOAD,
					 dev_name(&client->dev));
	if (!info->shdlc) {
		dev_err(&client->dev, "Cannot allocate nfc shdlc.\n");
		r = -ENOMEM;
		goto err_allocshdlc;
	}

	nfc_shdlc_set_clientdata(info->shdlc, info);

	return 0;

err_allocshdlc:
	free_irq(client->irq, info);

err_rti:
	if (pdata->free_resources != NULL)
		pdata->free_resources();

err_pdata:
	kfree(info);

err_info_alloc:
	return r;
}

static __devexit int pn544_hci_remove(struct i2c_client *client)
{
	struct pn544_hci_info *info = i2c_get_clientdata(client);
	struct pn544_nfc_platform_data *pdata = client->dev.platform_data;

	dev_dbg(&client->dev, "%s\n", __func__);

	nfc_shdlc_free(info->shdlc);

	if (info->state != PN544_ST_COLD) {
		if (pdata->disable)
			pdata->disable();
	}

	free_irq(client->irq, info);
	if (pdata->free_resources)
		pdata->free_resources();

	kfree(info);

	return 0;
}

static struct i2c_driver pn544_hci_driver = {
	.driver = {
		   .name = PN544_HCI_DRIVER_NAME,
		  },
	.probe = pn544_hci_probe,
	.id_table = pn544_hci_id_table,
	.remove = __devexit_p(pn544_hci_remove),
};

static int __init pn544_hci_init(void)
{
	int r;

	pr_debug(DRIVER_DESC ": %s\n", __func__);

	r = i2c_add_driver(&pn544_hci_driver);
	if (r) {
		pr_err(PN544_HCI_DRIVER_NAME ": driver registration failed\n");
		return r;
	}

	return 0;
}

static void __exit pn544_hci_exit(void)
{
	i2c_del_driver(&pn544_hci_driver);
}

module_init(pn544_hci_init);
module_exit(pn544_hci_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION(DRIVER_DESC);