drivers/nfc/microread/i2c.c - arm/linux - Git at Google

 /*
  * HCI based Driver for Inside Secure microread NFC Chip - i2c layer
  *
  * Copyright (C) 2013 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, see <http://www.gnu.org/licenses/>.
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/module.h>
 #include <linux/i2c.h>
 #include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/interrupt.h>
 #include <linux/gpio.h>

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

 #include "microread.h"

 #define MICROREAD_I2C_DRIVER_NAME "microread"

 #define MICROREAD_I2C_FRAME_HEADROOM 1
 #define MICROREAD_I2C_FRAME_TAILROOM 1

 /* framing in HCI mode */
 #define MICROREAD_I2C_LLC_LEN		1
 #define MICROREAD_I2C_LLC_CRC		1
 #define MICROREAD_I2C_LLC_LEN_CRC	(MICROREAD_I2C_LLC_LEN + \
 					MICROREAD_I2C_LLC_CRC)
 #define MICROREAD_I2C_LLC_MIN_SIZE	(1 + MICROREAD_I2C_LLC_LEN_CRC)
 #define MICROREAD_I2C_LLC_MAX_PAYLOAD	29
 #define MICROREAD_I2C_LLC_MAX_SIZE	(MICROREAD_I2C_LLC_LEN_CRC + 1 + \
 					MICROREAD_I2C_LLC_MAX_PAYLOAD)

 struct microread_i2c_phy {
 	struct i2c_client *i2c_dev;
 	struct nfc_hci_dev *hdev;

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

 #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 microread_i2c_add_len_crc(struct sk_buff *skb)
 {
 	int i;
 	u8 crc = 0;
 	int len;

 	len = skb->len;
 	*(u8 *)skb_push(skb, 1) = len;

 	for (i = 0; i < skb->len; i++)
 		crc = crc ^ skb->data[i];

 	skb_put_u8(skb, crc);
 }

 static void microread_i2c_remove_len_crc(struct sk_buff *skb)
 {
 	skb_pull(skb, MICROREAD_I2C_FRAME_HEADROOM);
 	skb_trim(skb, MICROREAD_I2C_FRAME_TAILROOM);
 }

 static int check_crc(struct sk_buff *skb)
 {
 	int i;
 	u8 crc = 0;

 	for (i = 0; i < skb->len - 1; i++)
 		crc = crc ^ skb->data[i];

 	if (crc != skb->data[skb->len-1]) {
 		pr_err("CRC error 0x%x != 0x%x\n", crc, skb->data[skb->len-1]);
 		pr_info("%s: BAD CRC\n", __func__);
 		return -EPERM;
 	}

 	return 0;
 }

 static int microread_i2c_enable(void *phy_id)
 {
 	return 0;
 }

 static void microread_i2c_disable(void *phy_id)
 {
 	return;
 }

 static int microread_i2c_write(void *phy_id, struct sk_buff *skb)
 {
 	int r;
 	struct microread_i2c_phy *phy = phy_id;
 	struct i2c_client *client = phy->i2c_dev;

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

 	usleep_range(3000, 6000);

 	microread_i2c_add_len_crc(skb);

 	I2C_DUMP_SKB("i2c frame written", skb);

 	r = i2c_master_send(client, skb->data, skb->len);

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

 	if (r >= 0) {
 		if (r != skb->len)
 			r = -EREMOTEIO;
 		else
 			r = 0;
 	}

 	microread_i2c_remove_len_crc(skb);

 	return r;
 }


 static int microread_i2c_read(struct microread_i2c_phy *phy,
 			      struct sk_buff **skb)
 {
 	int r;
 	u8 len;
 	u8 tmp[MICROREAD_I2C_LLC_MAX_SIZE - 1];
 	struct i2c_client *client = phy->i2c_dev;

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

 	if ((len < MICROREAD_I2C_LLC_MIN_SIZE) ||
 	    (len > MICROREAD_I2C_LLC_MAX_SIZE)) {
 		nfc_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_u8(*skb, len);

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

 	I2C_DUMP_SKB("cc frame read", *skb);

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

 	skb_pull(*skb, 1);
 	skb_trim(*skb, (*skb)->len - MICROREAD_I2C_FRAME_TAILROOM);

 	usleep_range(3000, 6000);

 	return 0;

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

 	usleep_range(3000, 6000);

 	return r;
 }

 static irqreturn_t microread_i2c_irq_thread_fn(int irq, void *phy_id)
 {
 	struct microread_i2c_phy *phy = phy_id;
 	struct sk_buff *skb = NULL;
 	int r;

 	if (!phy || irq != phy->i2c_dev->irq) {
 		WARN_ON_ONCE(1);
 		return IRQ_NONE;
 	}

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

 	r = microread_i2c_read(phy, &skb);
 	if (r == -EREMOTEIO) {
 		phy->hard_fault = r;

 		nfc_hci_recv_frame(phy->hdev, NULL);

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

 	nfc_hci_recv_frame(phy->hdev, skb);

 	return IRQ_HANDLED;
 }

 static struct nfc_phy_ops i2c_phy_ops = {
 	.write = microread_i2c_write,
 	.enable = microread_i2c_enable,
 	.disable = microread_i2c_disable,
 };

 static int microread_i2c_probe(struct i2c_client *client,
 			       const struct i2c_device_id *id)
 {
 	struct microread_i2c_phy *phy;
 	int r;

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

 	phy = devm_kzalloc(&client->dev, sizeof(struct microread_i2c_phy),
 			   GFP_KERNEL);
 	if (!phy)
 		return -ENOMEM;

 	i2c_set_clientdata(client, phy);
 	phy->i2c_dev = client;

 	r = request_threaded_irq(client->irq, NULL, microread_i2c_irq_thread_fn,
 				 IRQF_TRIGGER_RISING | IRQF_ONESHOT,
 				 MICROREAD_I2C_DRIVER_NAME, phy);
 	if (r) {
 		nfc_err(&client->dev, "Unable to register IRQ handler\n");
 		return r;
 	}

 	r = microread_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
 			    MICROREAD_I2C_FRAME_HEADROOM,
 			    MICROREAD_I2C_FRAME_TAILROOM,
 			    MICROREAD_I2C_LLC_MAX_PAYLOAD, &phy->hdev);
 	if (r < 0)
 		goto err_irq;

 	nfc_info(&client->dev, "Probed\n");

 	return 0;

 err_irq:
 	free_irq(client->irq, phy);

 	return r;
 }

 static int microread_i2c_remove(struct i2c_client *client)
 {
 	struct microread_i2c_phy *phy = i2c_get_clientdata(client);

 	microread_remove(phy->hdev);

 	free_irq(client->irq, phy);

 	return 0;
 }

 static struct i2c_device_id microread_i2c_id[] = {
 	{ MICROREAD_I2C_DRIVER_NAME, 0},
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, microread_i2c_id);

 static struct i2c_driver microread_i2c_driver = {
 	.driver = {
 		.name = MICROREAD_I2C_DRIVER_NAME,
 	},
 	.probe		= microread_i2c_probe,
 	.remove		= microread_i2c_remove,
 	.id_table	= microread_i2c_id,
 };

 module_i2c_driver(microread_i2c_driver);

 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION(DRIVER_DESC);
	/*
	* HCI based Driver for Inside Secure microread NFC Chip - i2c layer
	*
	* Copyright (C) 2013 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, see <http://www.gnu.org/licenses/>.
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/module.h>
	#include <linux/i2c.h>
	#include <linux/delay.h>
	#include <linux/slab.h>
	#include <linux/interrupt.h>
	#include <linux/gpio.h>

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

	#include "microread.h"

	#define MICROREAD_I2C_DRIVER_NAME "microread"

	#define MICROREAD_I2C_FRAME_HEADROOM 1
	#define MICROREAD_I2C_FRAME_TAILROOM 1

	/* framing in HCI mode */
	#define MICROREAD_I2C_LLC_LEN 1
	#define MICROREAD_I2C_LLC_CRC 1
	#define MICROREAD_I2C_LLC_LEN_CRC (MICROREAD_I2C_LLC_LEN + \
	MICROREAD_I2C_LLC_CRC)
	#define MICROREAD_I2C_LLC_MIN_SIZE (1 + MICROREAD_I2C_LLC_LEN_CRC)
	#define MICROREAD_I2C_LLC_MAX_PAYLOAD 29
	#define MICROREAD_I2C_LLC_MAX_SIZE (MICROREAD_I2C_LLC_LEN_CRC + 1 + \
	MICROREAD_I2C_LLC_MAX_PAYLOAD)

	struct microread_i2c_phy {
	struct i2c_client *i2c_dev;
	struct nfc_hci_dev *hdev;

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

	#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 microread_i2c_add_len_crc(struct sk_buff *skb)
	{
	int i;
	u8 crc = 0;
	int len;

	len = skb->len;
	(u8 )skb_push(skb, 1) = len;

	for (i = 0; i < skb->len; i++)
	crc = crc ^ skb->data[i];

	skb_put_u8(skb, crc);
	}

	static void microread_i2c_remove_len_crc(struct sk_buff *skb)
	{
	skb_pull(skb, MICROREAD_I2C_FRAME_HEADROOM);
	skb_trim(skb, MICROREAD_I2C_FRAME_TAILROOM);
	}

	static int check_crc(struct sk_buff *skb)
	{
	int i;
	u8 crc = 0;

	for (i = 0; i < skb->len - 1; i++)
	crc = crc ^ skb->data[i];

	if (crc != skb->data[skb->len-1]) {
	pr_err("CRC error 0x%x != 0x%x\n", crc, skb->data[skb->len-1]);
	pr_info("%s: BAD CRC\n", __func__);
	return -EPERM;
	}

	return 0;
	}

	static int microread_i2c_enable(void *phy_id)
	{
	return 0;
	}

	static void microread_i2c_disable(void *phy_id)
	{
	return;
	}

	static int microread_i2c_write(void phy_id, struct sk_buff skb)
	{
	int r;
	struct microread_i2c_phy *phy = phy_id;
	struct i2c_client *client = phy->i2c_dev;

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

	usleep_range(3000, 6000);

	microread_i2c_add_len_crc(skb);

	I2C_DUMP_SKB("i2c frame written", skb);

	r = i2c_master_send(client, skb->data, skb->len);

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

	if (r >= 0) {
	if (r != skb->len)
	r = -EREMOTEIO;
	else
	r = 0;
	}

	microread_i2c_remove_len_crc(skb);

	return r;
	}


	static int microread_i2c_read(struct microread_i2c_phy *phy,
	struct sk_buff **skb)
	{
	int r;
	u8 len;
	u8 tmp[MICROREAD_I2C_LLC_MAX_SIZE - 1];
	struct i2c_client *client = phy->i2c_dev;

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

	if ((len < MICROREAD_I2C_LLC_MIN_SIZE) \|\|
	(len > MICROREAD_I2C_LLC_MAX_SIZE)) {
	nfc_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_u8(*skb, len);

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

	I2C_DUMP_SKB("cc frame read", *skb);

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

	skb_pull(*skb, 1);
	skb_trim(skb, (skb)->len - MICROREAD_I2C_FRAME_TAILROOM);

	usleep_range(3000, 6000);

	return 0;

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

	usleep_range(3000, 6000);

	return r;
	}

	static irqreturn_t microread_i2c_irq_thread_fn(int irq, void *phy_id)
	{
	struct microread_i2c_phy *phy = phy_id;
	struct sk_buff *skb = NULL;
	int r;

	if (!phy \|\| irq != phy->i2c_dev->irq) {
	WARN_ON_ONCE(1);
	return IRQ_NONE;
	}

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

	r = microread_i2c_read(phy, &skb);
	if (r == -EREMOTEIO) {
	phy->hard_fault = r;

	nfc_hci_recv_frame(phy->hdev, NULL);

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

	nfc_hci_recv_frame(phy->hdev, skb);

	return IRQ_HANDLED;
	}

	static struct nfc_phy_ops i2c_phy_ops = {
	.write = microread_i2c_write,
	.enable = microread_i2c_enable,
	.disable = microread_i2c_disable,
	};

	static int microread_i2c_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct microread_i2c_phy *phy;
	int r;

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

	phy = devm_kzalloc(&client->dev, sizeof(struct microread_i2c_phy),
	GFP_KERNEL);
	if (!phy)
	return -ENOMEM;

	i2c_set_clientdata(client, phy);
	phy->i2c_dev = client;

	r = request_threaded_irq(client->irq, NULL, microread_i2c_irq_thread_fn,
	IRQF_TRIGGER_RISING \| IRQF_ONESHOT,
	MICROREAD_I2C_DRIVER_NAME, phy);
	if (r) {
	nfc_err(&client->dev, "Unable to register IRQ handler\n");
	return r;
	}

	r = microread_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
	MICROREAD_I2C_FRAME_HEADROOM,
	MICROREAD_I2C_FRAME_TAILROOM,
	MICROREAD_I2C_LLC_MAX_PAYLOAD, &phy->hdev);
	if (r < 0)
	goto err_irq;

	nfc_info(&client->dev, "Probed\n");

	return 0;

	err_irq:
	free_irq(client->irq, phy);

	return r;
	}

	static int microread_i2c_remove(struct i2c_client *client)
	{
	struct microread_i2c_phy *phy = i2c_get_clientdata(client);

	microread_remove(phy->hdev);

	free_irq(client->irq, phy);

	return 0;
	}

	static struct i2c_device_id microread_i2c_id[] = {
	{ MICROREAD_I2C_DRIVER_NAME, 0},
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, microread_i2c_id);

	static struct i2c_driver microread_i2c_driver = {
	.driver = {
	.name = MICROREAD_I2C_DRIVER_NAME,
	},
	.probe = microread_i2c_probe,
	.remove = microread_i2c_remove,
	.id_table = microread_i2c_id,
	};

	module_i2c_driver(microread_i2c_driver);

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