326 lines
6.8 KiB
C
326 lines
6.8 KiB
C
/*
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* HCI based Driver for Inside Secure microread NFC Chip - i2c layer
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*
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* Copyright (C) 2013 Intel Corporation. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/i2c.h>
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#include <linux/delay.h>
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#include <linux/slab.h>
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#include <linux/interrupt.h>
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#include <linux/gpio.h>
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#include <linux/nfc.h>
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#include <net/nfc/hci.h>
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#include <net/nfc/llc.h>
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#include "microread.h"
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#define MICROREAD_I2C_DRIVER_NAME "microread"
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#define MICROREAD_I2C_FRAME_HEADROOM 1
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#define MICROREAD_I2C_FRAME_TAILROOM 1
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/* framing in HCI mode */
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#define MICROREAD_I2C_LLC_LEN 1
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#define MICROREAD_I2C_LLC_CRC 1
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#define MICROREAD_I2C_LLC_LEN_CRC (MICROREAD_I2C_LLC_LEN + \
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MICROREAD_I2C_LLC_CRC)
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#define MICROREAD_I2C_LLC_MIN_SIZE (1 + MICROREAD_I2C_LLC_LEN_CRC)
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#define MICROREAD_I2C_LLC_MAX_PAYLOAD 29
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#define MICROREAD_I2C_LLC_MAX_SIZE (MICROREAD_I2C_LLC_LEN_CRC + 1 + \
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MICROREAD_I2C_LLC_MAX_PAYLOAD)
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struct microread_i2c_phy {
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struct i2c_client *i2c_dev;
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struct nfc_hci_dev *hdev;
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int irq;
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int hard_fault; /*
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* < 0 if hardware error occured (e.g. i2c err)
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* and prevents normal operation.
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*/
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};
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#define I2C_DUMP_SKB(info, skb) \
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do { \
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pr_debug("%s:\n", info); \
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print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET, \
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16, 1, (skb)->data, (skb)->len, 0); \
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} while (0)
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static void microread_i2c_add_len_crc(struct sk_buff *skb)
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{
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int i;
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u8 crc = 0;
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int len;
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len = skb->len;
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*skb_push(skb, 1) = len;
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for (i = 0; i < skb->len; i++)
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crc = crc ^ skb->data[i];
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*skb_put(skb, 1) = crc;
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}
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static void microread_i2c_remove_len_crc(struct sk_buff *skb)
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{
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skb_pull(skb, MICROREAD_I2C_FRAME_HEADROOM);
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skb_trim(skb, MICROREAD_I2C_FRAME_TAILROOM);
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}
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static int check_crc(struct sk_buff *skb)
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{
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int i;
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u8 crc = 0;
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for (i = 0; i < skb->len - 1; i++)
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crc = crc ^ skb->data[i];
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if (crc != skb->data[skb->len-1]) {
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pr_err("CRC error 0x%x != 0x%x\n", crc, skb->data[skb->len-1]);
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pr_info("%s: BAD CRC\n", __func__);
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return -EPERM;
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}
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return 0;
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}
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static int microread_i2c_enable(void *phy_id)
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{
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return 0;
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}
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static void microread_i2c_disable(void *phy_id)
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{
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return;
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}
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static int microread_i2c_write(void *phy_id, struct sk_buff *skb)
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{
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int r;
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struct microread_i2c_phy *phy = phy_id;
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struct i2c_client *client = phy->i2c_dev;
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if (phy->hard_fault != 0)
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return phy->hard_fault;
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usleep_range(3000, 6000);
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microread_i2c_add_len_crc(skb);
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I2C_DUMP_SKB("i2c frame written", skb);
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r = i2c_master_send(client, skb->data, skb->len);
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if (r == -EREMOTEIO) { /* Retry, chip was in standby */
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usleep_range(6000, 10000);
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r = i2c_master_send(client, skb->data, skb->len);
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}
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if (r >= 0) {
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if (r != skb->len)
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r = -EREMOTEIO;
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else
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r = 0;
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}
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microread_i2c_remove_len_crc(skb);
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return r;
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}
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static int microread_i2c_read(struct microread_i2c_phy *phy,
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struct sk_buff **skb)
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{
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int r;
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u8 len;
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u8 tmp[MICROREAD_I2C_LLC_MAX_SIZE - 1];
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struct i2c_client *client = phy->i2c_dev;
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r = i2c_master_recv(client, &len, 1);
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if (r != 1) {
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nfc_err(&client->dev, "cannot read len byte\n");
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return -EREMOTEIO;
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}
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if ((len < MICROREAD_I2C_LLC_MIN_SIZE) ||
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(len > MICROREAD_I2C_LLC_MAX_SIZE)) {
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nfc_err(&client->dev, "invalid len byte\n");
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r = -EBADMSG;
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goto flush;
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}
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*skb = alloc_skb(1 + len, GFP_KERNEL);
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if (*skb == NULL) {
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r = -ENOMEM;
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goto flush;
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}
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*skb_put(*skb, 1) = len;
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r = i2c_master_recv(client, skb_put(*skb, len), len);
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if (r != len) {
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kfree_skb(*skb);
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return -EREMOTEIO;
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}
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I2C_DUMP_SKB("cc frame read", *skb);
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r = check_crc(*skb);
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if (r != 0) {
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kfree_skb(*skb);
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r = -EBADMSG;
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goto flush;
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}
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skb_pull(*skb, 1);
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skb_trim(*skb, (*skb)->len - MICROREAD_I2C_FRAME_TAILROOM);
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usleep_range(3000, 6000);
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return 0;
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flush:
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if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0)
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r = -EREMOTEIO;
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usleep_range(3000, 6000);
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return r;
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}
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static irqreturn_t microread_i2c_irq_thread_fn(int irq, void *phy_id)
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{
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struct microread_i2c_phy *phy = phy_id;
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struct sk_buff *skb = NULL;
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int r;
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if (!phy || irq != phy->i2c_dev->irq) {
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WARN_ON_ONCE(1);
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return IRQ_NONE;
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}
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if (phy->hard_fault != 0)
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return IRQ_HANDLED;
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r = microread_i2c_read(phy, &skb);
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if (r == -EREMOTEIO) {
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phy->hard_fault = r;
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nfc_hci_recv_frame(phy->hdev, NULL);
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return IRQ_HANDLED;
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} else if ((r == -ENOMEM) || (r == -EBADMSG)) {
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return IRQ_HANDLED;
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}
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nfc_hci_recv_frame(phy->hdev, skb);
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return IRQ_HANDLED;
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}
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static struct nfc_phy_ops i2c_phy_ops = {
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.write = microread_i2c_write,
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.enable = microread_i2c_enable,
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.disable = microread_i2c_disable,
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};
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static int microread_i2c_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct microread_i2c_phy *phy;
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struct microread_nfc_platform_data *pdata =
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dev_get_platdata(&client->dev);
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int r;
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dev_dbg(&client->dev, "client %p\n", client);
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if (!pdata) {
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nfc_err(&client->dev, "client %p: missing platform data\n",
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client);
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return -EINVAL;
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}
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phy = devm_kzalloc(&client->dev, sizeof(struct microread_i2c_phy),
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GFP_KERNEL);
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if (!phy)
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return -ENOMEM;
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i2c_set_clientdata(client, phy);
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phy->i2c_dev = client;
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r = request_threaded_irq(client->irq, NULL, microread_i2c_irq_thread_fn,
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IRQF_TRIGGER_RISING | IRQF_ONESHOT,
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MICROREAD_I2C_DRIVER_NAME, phy);
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if (r) {
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nfc_err(&client->dev, "Unable to register IRQ handler\n");
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return r;
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}
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r = microread_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
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MICROREAD_I2C_FRAME_HEADROOM,
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MICROREAD_I2C_FRAME_TAILROOM,
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MICROREAD_I2C_LLC_MAX_PAYLOAD, &phy->hdev);
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if (r < 0)
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goto err_irq;
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nfc_info(&client->dev, "Probed\n");
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return 0;
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err_irq:
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free_irq(client->irq, phy);
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return r;
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}
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static int microread_i2c_remove(struct i2c_client *client)
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{
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struct microread_i2c_phy *phy = i2c_get_clientdata(client);
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microread_remove(phy->hdev);
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free_irq(client->irq, phy);
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return 0;
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}
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static struct i2c_device_id microread_i2c_id[] = {
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{ MICROREAD_I2C_DRIVER_NAME, 0},
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, microread_i2c_id);
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static struct i2c_driver microread_i2c_driver = {
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.driver = {
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.name = MICROREAD_I2C_DRIVER_NAME,
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},
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.probe = microread_i2c_probe,
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.remove = microread_i2c_remove,
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.id_table = microread_i2c_id,
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};
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module_i2c_driver(microread_i2c_driver);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION(DRIVER_DESC);
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