NFC: ST21NFCA: Add driver for STMicroelectronics ST21NFCA NFC Chip

source "drivers/nfc/pn544/Kconfig"

source "drivers/nfc/microread/Kconfig"

source "drivers/nfc/nfcmrvl/Kconfig"

source "drivers/nfc/st21nfca/Kconfig"

endmenu

obj-$(CONFIG_NFC_PORT100)	+= port100.o

obj-$(CONFIG_NFC_MRVL)		+= nfcmrvl/

obj-$(CONFIG_NFC_TRF7970A)	+= trf7970a.o

obj-$(CONFIG_NFC_ST21NFCA)  += st21nfca/

ccflags-$(CONFIG_NFC_DEBUG) := -DDEBUG

config NFC_ST21NFCA

	tristate "STMicroelectronics ST21NFCA NFC driver"

	depends on NFC_HCI

	select CRC_CCITT

	default n

	---help---

	  STMicroelectronics ST21NFCA core driver. It implements the chipset

	  HCI logic and hooks into the NFC kernel APIs. Physical layers will

	  register against it.

	  To compile this driver as a module, choose m here. The module will

	  be called st21nfca.

	  Say N if unsure.

config NFC_ST21NFCA_I2C

	tristate "NFC ST21NFCA i2c support"

	depends on NFC_ST21NFCA && I2C && NFC_SHDLC

	---help---

	  This module adds support for the STMicroelectronics st21nfca i2c interface.

	  Select this if your platform is using the i2c bus.

	  If you choose to build a module, it'll be called st21nfca_i2c.

	  Say N if unsure.

#

# Makefile for ST21NFCA HCI based NFC driver

#

st21nfca_i2c-objs  = i2c.o

obj-$(CONFIG_NFC_ST21NFCA)     += st21nfca.o

obj-$(CONFIG_NFC_ST21NFCA_I2C) += st21nfca_i2c.o

/*

 * I2C Link Layer for ST21NFCA HCI based Driver

 * Copyright (C) 2014  STMicroelectronics SAS. 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, see <http://www.gnu.org/licenses/>.

 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/crc-ccitt.h>

#include <linux/module.h>

#include <linux/i2c.h>

#include <linux/gpio.h>

#include <linux/miscdevice.h>

#include <linux/interrupt.h>

#include <linux/delay.h>

#include <linux/nfc.h>

#include <linux/firmware.h>

#include <linux/unaligned/access_ok.h>

#include <linux/platform_data/st21nfca.h>

#include <net/nfc/hci.h>

#include <net/nfc/llc.h>

#include <net/nfc/nfc.h>

#include "st21nfca.h"

/*

 * Every frame starts with ST21NFCA_SOF_EOF and ends with ST21NFCA_SOF_EOF.

 * Because ST21NFCA_SOF_EOF is a possible data value, there is a mecanism

 * called byte stuffing has been introduced.

 *

 * if byte == ST21NFCA_SOF_EOF or ST21NFCA_ESCAPE_BYTE_STUFFING

 * - insert ST21NFCA_ESCAPE_BYTE_STUFFING (escape byte)

 * - xor byte with ST21NFCA_BYTE_STUFFING_MASK

 */

#define ST21NFCA_SOF_EOF		0x7e

#define ST21NFCA_BYTE_STUFFING_MASK	0x20

#define ST21NFCA_ESCAPE_BYTE_STUFFING	0x7d

/* SOF + 00 fill size */

#define ST21NFCA_FRAME_HEADROOM			2

/* 4 bytes crc (worst case byte stuffing) + EOF */

#define ST21NFCA_FRAME_TAILROOM 5

#define ST21NFCA_HCI_I2C_DRIVER_NAME "st21nfca_hci_i2c"

static struct i2c_device_id st21nfca_hci_i2c_id_table[] = {

	{ST21NFCA_HCI_DRIVER_NAME, 0},

	{}

};

MODULE_DEVICE_TABLE(i2c, st21nfca_hci_i2c_id_table);

struct st21nfca_i2c_phy {

	struct i2c_client *i2c_dev;

	struct nfc_hci_dev *hdev;

	unsigned int gpio_ena;

	unsigned int gpio_irq;

	unsigned int irq_polarity;

	struct sk_buff *pending_skb;

	int current_read_len;

	/*

	 * crc might have fail because i2c macro

	 * is disable due to other interface activity

	 */

	int crc_trials;

	int powered;

	int run_mode;

	/*

	 * < 0 if hardware error occured (e.g. i2c err)

	 * and prevents normal operation.

	 */

	int hard_fault;

};

static u8 len_seq[] = { 13, 24, 15, 29 };

static u16 wait_tab[] = { 2, 3, 5, 15, 20, 40};

#define I2C_DUMP_SKB(info, skb)					\

do {								\

	pr_debug("%s:\n", info);				\

	print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET,	\

		       16, 1, (skb)->data, (skb)->len, 0);	\

} while (0)

static void st21nfca_hci_platform_init(struct st21nfca_i2c_phy *phy)

{

	u16 wait_tab[] = { 50, 300, 1000 };

	char reboot_cmd[] = { 0x7E, 0x66, 0x48, 0xF6, 0x7E };

	u8 tmp[ST21NFCA_HCI_LLC_MAX_SIZE];

	int i, r = -1;

	for (i = 0; i < ARRAY_SIZE(wait_tab) && r < 0; i++)

		r = i2c_master_recv(phy->i2c_dev, tmp,

				    ST21NFCA_HCI_LLC_MAX_SIZE);

	r = -1;

	for (i = 0; i < ARRAY_SIZE(wait_tab) && r < 0; i++)

		r = i2c_master_send(phy->i2c_dev, reboot_cmd,

				    sizeof(reboot_cmd));

	usleep_range(1000, 1500);

}

static int st21nfca_hci_i2c_enable(void *phy_id)

{

	struct st21nfca_i2c_phy *phy = phy_id;

	gpio_set_value(phy->gpio_ena, 1);

	phy->powered = 1;

	phy->run_mode = ST21NFCA_HCI_MODE;

	usleep_range(10000, 15000);

	return 0;

}

static void st21nfca_hci_i2c_disable(void *phy_id)

{

	struct st21nfca_i2c_phy *phy = phy_id;

	pr_info("\n");

	gpio_set_value(phy->gpio_ena, 0);

	phy->powered = 0;

}

static int st21nfca_hci_add_len_crc(struct sk_buff *skb)

{

	int ret = 2;

	u16 crc;

	u8 tmp;

	*skb_push(skb, 1) = 0;

	crc = crc_ccitt(0xffff, skb->data, skb->len);

	crc = ~crc;

	tmp = crc & 0x00ff;

	*skb_put(skb, 1) = tmp;

	tmp = (crc >> 8) & 0x00ff;

	*skb_put(skb, 1) = tmp;

	return ret;

}

static void st21nfca_hci_remove_len_crc(struct sk_buff *skb, int crc_len)

{

	skb_pull(skb, ST21NFCA_FRAME_HEADROOM);

	skb_trim(skb, crc_len);

}

/*

 * Writing a frame must not return the number of written bytes.

 * It must return either zero for success, or <0 for error.

 * In addition, it must not alter the skb

 */

static int st21nfca_hci_i2c_write(void *phy_id, struct sk_buff *skb)

{

	int r = -1, i, j, len;

	struct st21nfca_i2c_phy *phy = phy_id;

	struct i2c_client *client = phy->i2c_dev;

	u16 wait_tab[] = { 2, 3, 5, 15, 20, 40};

	u8 tmp[ST21NFCA_HCI_LLC_MAX_SIZE * 2];

	I2C_DUMP_SKB("st21nfca_hci_i2c_write", skb);

	if (phy->hard_fault != 0)

		return phy->hard_fault;

	/*

	 * Compute CRC before byte stuffing computation on frame

	 * Note st21nfca_hci_add_len_crc is doing a byte stuffing

	 * on its own value

	 */

	len = st21nfca_hci_add_len_crc(skb);

	/* add ST21NFCA_SOF_EOF on tail */

	*skb_put(skb, 1) = ST21NFCA_SOF_EOF;

	/* add ST21NFCA_SOF_EOF on head */

	*skb_push(skb, 1) = ST21NFCA_SOF_EOF;

	/*

	 * Compute byte stuffing

	 * if byte == ST21NFCA_SOF_EOF or ST21NFCA_ESCAPE_BYTE_STUFFING

	 * insert ST21NFCA_ESCAPE_BYTE_STUFFING (escape byte)

	 * xor byte with ST21NFCA_BYTE_STUFFING_MASK

	 */

	tmp[0] = skb->data[0];

	for (i = 1, j = 1; i < skb->len - 1; i++, j++) {

		if (skb->data[i] == ST21NFCA_SOF_EOF

		    || skb->data[i] == ST21NFCA_ESCAPE_BYTE_STUFFING) {

			tmp[j] = ST21NFCA_ESCAPE_BYTE_STUFFING;

			j++;

			tmp[j] = skb->data[i] ^ ST21NFCA_BYTE_STUFFING_MASK;

		} else {

			tmp[j] = skb->data[i];

		}

	}

	tmp[j] = skb->data[i];

	j++;

	/*

	 * Manage sleep mode

	 * Try 3 times to send data with delay between each

	 */

	for (i = 0; i < ARRAY_SIZE(wait_tab) && r < 0; i++) {

		r = i2c_master_send(client, tmp, j);

		if (r < 0)

			msleep(wait_tab[i]);

	}

	if (r >= 0) {

		if (r != j)

			r = -EREMOTEIO;

		else

			r = 0;

	}

	st21nfca_hci_remove_len_crc(skb, len);

	return r;

}

static int get_frame_size(u8 *buf, int buflen)

{

	int len = 0;

	if (buf[len + 1] == ST21NFCA_SOF_EOF)

		return 0;

	for (len = 1; len < buflen && buf[len] != ST21NFCA_SOF_EOF; len++)

		;

	return len;

}

static int check_crc(u8 *buf, int buflen)

{

	u16 crc;

	crc = crc_ccitt(0xffff, buf, buflen - 2);

	crc = ~crc;

	if (buf[buflen - 2] != (crc & 0xff) || buf[buflen - 1] != (crc >> 8)) {

		pr_err(ST21NFCA_HCI_DRIVER_NAME

		       ": CRC error 0x%x != 0x%x 0x%x\n", crc, buf[buflen - 1],

		       buf[buflen - 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;

}

/*

 * Prepare received data for upper layer.

 * Received data include byte stuffing, crc and sof/eof

 * which is not usable by hci part.

 * returns:

 * frame size without sof/eof, header and byte stuffing

 * -EBADMSG : frame was incorrect and discarded

 */

static int st21nfca_hci_i2c_repack(struct sk_buff *skb)

{

	int i, j, r, size;

	if (skb->len < 1 || (skb->len > 1 && skb->data[1] != 0))

		return -EBADMSG;

	size = get_frame_size(skb->data, skb->len);

	if (size > 0) {

		skb_trim(skb, size);

		/* remove ST21NFCA byte stuffing for upper layer */

		for (i = 1, j = 0; i < skb->len; i++) {

			if (skb->data[i] ==

					(u8) ST21NFCA_ESCAPE_BYTE_STUFFING) {

				skb->data[i] =

				    skb->data[i +

					      1] | ST21NFCA_BYTE_STUFFING_MASK;

				i++;

				j++;

			}

			skb->data[i] = skb->data[i + j];

		}

		/* remove byte stuffing useless byte */

		skb_trim(skb, i - j);

		/* remove ST21NFCA_SOF_EOF from head */

		skb_pull(skb, 1);

		r = check_crc(skb->data, skb->len);

		if (r != 0) {

			i = 0;

			return -EBADMSG;

		}

		/* remove headbyte */

		skb_pull(skb, 1);

		/* remove crc. Byte Stuffing is already removed here */

		skb_trim(skb, skb->len - 2);

		return skb->len;

	}

	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:

 * frame size : if received frame is complete (find ST21NFCA_SOF_EOF at

 * end of read)

 * -EAGAIN : if received frame is incomplete (not find ST21NFCA_SOF_EOF

 * at end of read)

 * -EREMOTEIO : i2c read error (fatal)

 * -EBADMSG : frame was incorrect and discarded

 * (value returned from st21nfca_hci_i2c_repack)

 * -EIO : if no ST21NFCA_SOF_EOF is found after reaching

 * the read length end sequence

 */

static int st21nfca_hci_i2c_read(struct st21nfca_i2c_phy *phy,

				 struct sk_buff *skb)

{

	int r, i;

	u8 len;

	struct i2c_client *client = phy->i2c_dev;

	if (phy->current_read_len < ARRAY_SIZE(len_seq)) {

		len = len_seq[phy->current_read_len];

		/*

		 * Add retry mecanism

		 * Operation on I2C interface may fail in case of operation on

		 * RF or SWP interface

		 */

		r = 0;

		for (i = 0; i < ARRAY_SIZE(wait_tab) && r <= 0; i++) {

			r = i2c_master_recv(client, skb_put(skb, len), len);

			if (r < 0)

				msleep(wait_tab[i]);

		}

		if (r != len) {

			phy->current_read_len = 0;

			return -EREMOTEIO;

		}

		if (memchr(skb->data + 2, ST21NFCA_SOF_EOF,

				skb->len - 2) != NULL) {

			phy->current_read_len = 0;

			return st21nfca_hci_i2c_repack(skb);

		}

		phy->current_read_len++;

		return -EAGAIN;

	}

	return -EIO;

}

/*

 * Reads an shdlc frame from the chip. This is not as straightforward as it

 * seems. The frame format is data-crc, and corruption can occur anywhere

 * while transiting on i2c bus, such that we could read an invalid data.

 * The tricky case is when we read a corrupted data or crc. We must detect

 * this here in order to determine that data can be transmitted to the hci

 * core. This is the reason why we check the crc here.

 * The CLF will repeat a frame until we send a RR on that frame.

 *

 * On ST21NFCA, IRQ goes in idle when read starts. As no size information are

 * available in the incoming data, other IRQ might come. Every IRQ will trigger

 * a read sequence with different length and will fill the current frame.

 * The reception is complete once we reach a ST21NFCA_SOF_EOF.

 */

static irqreturn_t st21nfca_hci_irq_thread_fn(int irq, void *phy_id)

{

	struct st21nfca_i2c_phy *phy = phy_id;

	struct i2c_client *client;

	int r;

	if (!phy || irq != phy->i2c_dev->irq) {

		WARN_ON_ONCE(1);

		return IRQ_NONE;

	}

	client = phy->i2c_dev;

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

	if (phy->hard_fault != 0)

		return IRQ_HANDLED;

	r = st21nfca_hci_i2c_read(phy, phy->pending_skb);

	if (r == -EREMOTEIO) {

		phy->hard_fault = r;

		nfc_hci_recv_frame(phy->hdev, NULL);

		return IRQ_HANDLED;

	} else if (r == -EAGAIN || r == -EIO) {

		return IRQ_HANDLED;

	} else if (r == -EBADMSG && phy->crc_trials < ARRAY_SIZE(wait_tab)) {

		/*

		 * With ST21NFCA, only one interface (I2C, RF or SWP)

		 * may be active at a time.

		 * Having incorrect crc is usually due to i2c macrocell

		 * deactivation in the middle of a transmission.

		 * It may generate corrupted data on i2c.

		 * We give sometime to get i2c back.

		 * The complete frame will be repeated.

		 */

		msleep(wait_tab[phy->crc_trials]);

		phy->crc_trials++;

		phy->current_read_len = 0;

	} else if (r > 0) {

		/*

		 * We succeeded to read data from the CLF and

		 * data is valid.

		 * Reset counter.

		 */

		nfc_hci_recv_frame(phy->hdev, phy->pending_skb);

		phy->crc_trials = 0;

	}

	phy->pending_skb = alloc_skb(ST21NFCA_HCI_LLC_MAX_SIZE * 2, GFP_KERNEL);

	if (phy->pending_skb == NULL) {

		phy->hard_fault = -ENOMEM;

		nfc_hci_recv_frame(phy->hdev, NULL);

	}

	return IRQ_HANDLED;

}

static struct nfc_phy_ops i2c_phy_ops = {

	.write = st21nfca_hci_i2c_write,

	.enable = st21nfca_hci_i2c_enable,

	.disable = st21nfca_hci_i2c_disable,

};

static int st21nfca_request_resources(struct st21nfca_i2c_phy *phy,

				      struct i2c_client *client)

{

	struct st21nfca_nfc_platform_data *pdata;

	int r;

	pdata = client->dev.platform_data;

	if (pdata == NULL) {

		nfc_err(&client->dev, "No platform data\n");

		return -EINVAL;

	}

	/* store for later use */

	phy->gpio_irq = pdata->gpio_irq;

	phy->gpio_ena = pdata->gpio_ena;

	phy->irq_polarity = pdata->irq_polarity;

	phy->i2c_dev = client;

	r = devm_gpio_request(&client->dev, phy->gpio_irq, "wake_up");

	if (r) {

		pr_err("%s : gpio_request failed\n", __FILE__);

		return -ENODEV;

	}

	r = gpio_direction_input(phy->gpio_irq);

	if (r) {

		pr_err("%s : gpio_direction_input failed\n", __FILE__);

		return -ENODEV;

	}

	if (phy->gpio_ena != 0) {

		r = devm_gpio_request(&client->dev,

					phy->gpio_ena, "clf_enable");

		if (r) {

			pr_err("%s : ena gpio_request failed\n", __FILE__);

			return -ENODEV;

		}

		r = gpio_direction_output(phy->gpio_ena, 1);

		if (r) {

			pr_err("%s : ena gpio_direction_output failed\n",

			       __FILE__);

			return -ENODEV;

		}

	}

	phy->pending_skb = alloc_skb(ST21NFCA_HCI_LLC_MAX_SIZE * 2, GFP_KERNEL);

	if (phy->pending_skb == NULL)

		return -ENOMEM;

	phy->current_read_len = 0;

	phy->crc_trials = 0;

	return r;

}

static int st21nfca_hci_i2c_probe(struct i2c_client *client,

				  const struct i2c_device_id *id)

{

	struct st21nfca_i2c_phy *phy;

	struct st21nfca_nfc_platform_data *pdata;

	int r = 0;

	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)) {

		nfc_err(&client->dev, "Need I2C_FUNC_I2C\n");

		return -ENODEV;

	}

	phy = devm_kzalloc(&client->dev, sizeof(struct st21nfca_i2c_phy),

			   GFP_KERNEL);

	if (!phy) {

		nfc_err(&client->dev,

			"Cannot allocate memory for st21nfca i2c phy.\n");

		return -ENOMEM;

	}

	phy->i2c_dev = client;

	i2c_set_clientdata(client, phy);

	pdata = client->dev.platform_data;

	if (pdata == NULL) {

		nfc_err(&client->dev, "No platform data\n");

		return -EINVAL;

	}

	r = st21nfca_request_resources(phy, client);

	if (r) {

		nfc_err(&client->dev, "Cannot get platform resources\n");

		return r;

	}

	st21nfca_hci_platform_init(phy);

	r = devm_request_threaded_irq(&client->dev, client->irq, NULL,

				st21nfca_hci_irq_thread_fn,

				phy->irq_polarity | IRQF_ONESHOT,

				ST21NFCA_HCI_DRIVER_NAME, phy);

	if (r < 0) {

		nfc_err(&client->dev, "Unable to register IRQ handler\n");

		return r;

	}

	r = st21nfca_hci_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,

			       ST21NFCA_FRAME_HEADROOM, ST21NFCA_FRAME_TAILROOM,

			       ST21NFCA_HCI_LLC_MAX_PAYLOAD, &phy->hdev);

	if (r < 0)

		return r;

	return 0;

}

static int st21nfca_hci_i2c_remove(struct i2c_client *client)

{

	struct st21nfca_i2c_phy *phy = i2c_get_clientdata(client);

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

	st21nfca_hci_remove(phy->hdev);

	if (phy->powered)

		st21nfca_hci_i2c_disable(phy);

	return 0;

}

static struct i2c_driver st21nfca_hci_i2c_driver = {

	.driver = {

		   .name = ST21NFCA_HCI_I2C_DRIVER_NAME,

		   },

	.probe = st21nfca_hci_i2c_probe,

	.id_table = st21nfca_hci_i2c_id_table,

	.remove = st21nfca_hci_i2c_remove,

};

module_i2c_driver(st21nfca_hci_i2c_driver);

MODULE_LICENSE("GPL");

MODULE_DESCRIPTION(DRIVER_DESC);