// SPDX-License-Identifier: GPL-2.0-only/* * HCI based Driver for Inside Secure microread NFC Chip - i2c layer * * Copyright (C) 2013 Intel Corporation. All rights reserved. */ #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/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(const 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 const 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){	struct microread_i2c_phy *phy;	int r; 	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; 	return 0; err_irq:	free_irq(client->irq, phy); 	return r;} static void 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);} static const struct i2c_device_id microread_i2c_id[] = {	{ .name = MICROREAD_I2C_DRIVER_NAME },	{ }};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);