drivers/nfc/microread/i2c.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * HCI based Driver for Inside Secure microread NFC Chip - i2c layer
   4  *
   5  * Copyright (C) 2013 Intel Corporation. All rights reserved.
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/module.h>
  11 #include <linux/i2c.h>
  12 #include <linux/delay.h>
  13 #include <linux/slab.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/gpio.h>
  16
  17 #include <linux/nfc.h>
  18 #include <net/nfc/hci.h>
  19 #include <net/nfc/llc.h>
  20
  21 #include "microread.h"
  22
  23 #define MICROREAD_I2C_DRIVER_NAME "microread"
  24
  25 #define MICROREAD_I2C_FRAME_HEADROOM 1
  26 #define MICROREAD_I2C_FRAME_TAILROOM 1
  27
  28 /* framing in HCI mode */
  29 #define MICROREAD_I2C_LLC_LEN           1
  30 #define MICROREAD_I2C_LLC_CRC           1
  31 #define MICROREAD_I2C_LLC_LEN_CRC       (MICROREAD_I2C_LLC_LEN + \
  32                                         MICROREAD_I2C_LLC_CRC)
  33 #define MICROREAD_I2C_LLC_MIN_SIZE      (1 + MICROREAD_I2C_LLC_LEN_CRC)
  34 #define MICROREAD_I2C_LLC_MAX_PAYLOAD   29
  35 #define MICROREAD_I2C_LLC_MAX_SIZE      (MICROREAD_I2C_LLC_LEN_CRC + 1 + \
  36                                         MICROREAD_I2C_LLC_MAX_PAYLOAD)
  37
  38 struct microread_i2c_phy {
  39         struct i2c_client *i2c_dev;
  40         struct nfc_hci_dev *hdev;
  41
  42         int hard_fault;         /*
  43                                  * < 0 if hardware error occured (e.g. i2c err)
  44                                  * and prevents normal operation.
  45                                  */
  46 };
  47
  48 #define I2C_DUMP_SKB(info, skb)                                 \
  49 do {                                                            \
  50         pr_debug("%s:\n", info);                                \
  51         print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET, \
  52                        16, 1, (skb)->data, (skb)->len, 0);      \
  53 } while (0)
  54
  55 static void microread_i2c_add_len_crc(struct sk_buff *skb)
  56 {
  57         int i;
  58         u8 crc = 0;
  59         int len;
  60
  61         len = skb->len;
  62         *(u8 *)skb_push(skb, 1) = len;
  63
  64         for (i = 0; i < skb->len; i++)
  65                 crc = crc ^ skb->data[i];
  66
  67         skb_put_u8(skb, crc);
  68 }
  69
  70 static void microread_i2c_remove_len_crc(struct sk_buff *skb)
  71 {
  72         skb_pull(skb, MICROREAD_I2C_FRAME_HEADROOM);
  73         skb_trim(skb, MICROREAD_I2C_FRAME_TAILROOM);
  74 }
  75
  76 static int check_crc(const struct sk_buff *skb)
  77 {
  78         int i;
  79         u8 crc = 0;
  80
  81         for (i = 0; i < skb->len - 1; i++)
  82                 crc = crc ^ skb->data[i];
  83
  84         if (crc != skb->data[skb->len-1]) {
  85                 pr_err("CRC error 0x%x != 0x%x\n", crc, skb->data[skb->len-1]);
  86                 pr_info("%s: BAD CRC\n", __func__);
  87                 return -EPERM;
  88         }
  89
  90         return 0;
  91 }
  92
  93 static int microread_i2c_enable(void *phy_id)
  94 {
  95         return 0;
  96 }
  97
  98 static void microread_i2c_disable(void *phy_id)
  99 {
 100         return;
 101 }
 102
 103 static int microread_i2c_write(void *phy_id, struct sk_buff *skb)
 104 {
 105         int r;
 106         struct microread_i2c_phy *phy = phy_id;
 107         struct i2c_client *client = phy->i2c_dev;
 108
 109         if (phy->hard_fault != 0)
 110                 return phy->hard_fault;
 111
 112         usleep_range(3000, 6000);
 113
 114         microread_i2c_add_len_crc(skb);
 115
 116         I2C_DUMP_SKB("i2c frame written", skb);
 117
 118         r = i2c_master_send(client, skb->data, skb->len);
 119
 120         if (r == -EREMOTEIO) {  /* Retry, chip was in standby */
 121                 usleep_range(6000, 10000);
 122                 r = i2c_master_send(client, skb->data, skb->len);
 123         }
 124
 125         if (r >= 0) {
 126                 if (r != skb->len)
 127                         r = -EREMOTEIO;
 128                 else
 129                         r = 0;
 130         }
 131
 132         microread_i2c_remove_len_crc(skb);
 133
 134         return r;
 135 }
 136
 137
 138 static int microread_i2c_read(struct microread_i2c_phy *phy,
 139                               struct sk_buff **skb)
 140 {
 141         int r;
 142         u8 len;
 143         u8 tmp[MICROREAD_I2C_LLC_MAX_SIZE - 1];
 144         struct i2c_client *client = phy->i2c_dev;
 145
 146         r = i2c_master_recv(client, &len, 1);
 147         if (r != 1) {
 148                 nfc_err(&client->dev, "cannot read len byte\n");
 149                 return -EREMOTEIO;
 150         }
 151
 152         if ((len < MICROREAD_I2C_LLC_MIN_SIZE) ||
 153             (len > MICROREAD_I2C_LLC_MAX_SIZE)) {
 154                 nfc_err(&client->dev, "invalid len byte\n");
 155                 r = -EBADMSG;
 156                 goto flush;
 157         }
 158
 159         *skb = alloc_skb(1 + len, GFP_KERNEL);
 160         if (*skb == NULL) {
 161                 r = -ENOMEM;
 162                 goto flush;
 163         }
 164
 165         skb_put_u8(*skb, len);
 166
 167         r = i2c_master_recv(client, skb_put(*skb, len), len);
 168         if (r != len) {
 169                 kfree_skb(*skb);
 170                 return -EREMOTEIO;
 171         }
 172
 173         I2C_DUMP_SKB("cc frame read", *skb);
 174
 175         r = check_crc(*skb);
 176         if (r != 0) {
 177                 kfree_skb(*skb);
 178                 r = -EBADMSG;
 179                 goto flush;
 180         }
 181
 182         skb_pull(*skb, 1);
 183         skb_trim(*skb, (*skb)->len - MICROREAD_I2C_FRAME_TAILROOM);
 184
 185         usleep_range(3000, 6000);
 186
 187         return 0;
 188
 189 flush:
 190         if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0)
 191                 r = -EREMOTEIO;
 192
 193         usleep_range(3000, 6000);
 194
 195         return r;
 196 }
 197
 198 static irqreturn_t microread_i2c_irq_thread_fn(int irq, void *phy_id)
 199 {
 200         struct microread_i2c_phy *phy = phy_id;
 201         struct sk_buff *skb = NULL;
 202         int r;
 203
 204         if (!phy || irq != phy->i2c_dev->irq) {
 205                 WARN_ON_ONCE(1);
 206                 return IRQ_NONE;
 207         }
 208
 209         if (phy->hard_fault != 0)
 210                 return IRQ_HANDLED;
 211
 212         r = microread_i2c_read(phy, &skb);
 213         if (r == -EREMOTEIO) {
 214                 phy->hard_fault = r;
 215
 216                 nfc_hci_recv_frame(phy->hdev, NULL);
 217
 218                 return IRQ_HANDLED;
 219         } else if ((r == -ENOMEM) || (r == -EBADMSG)) {
 220                 return IRQ_HANDLED;
 221         }
 222
 223         nfc_hci_recv_frame(phy->hdev, skb);
 224
 225         return IRQ_HANDLED;
 226 }
 227
 228 static const struct nfc_phy_ops i2c_phy_ops = {
 229         .write = microread_i2c_write,
 230         .enable = microread_i2c_enable,
 231         .disable = microread_i2c_disable,
 232 };
 233
 234 static int microread_i2c_probe(struct i2c_client *client,
 235                                const struct i2c_device_id *id)
 236 {
 237         struct microread_i2c_phy *phy;
 238         int r;
 239
 240         dev_dbg(&client->dev, "client %p\n", client);
 241
 242         phy = devm_kzalloc(&client->dev, sizeof(struct microread_i2c_phy),
 243                            GFP_KERNEL);
 244         if (!phy)
 245                 return -ENOMEM;
 246
 247         i2c_set_clientdata(client, phy);
 248         phy->i2c_dev = client;
 249
 250         r = request_threaded_irq(client->irq, NULL, microread_i2c_irq_thread_fn,
 251                                  IRQF_TRIGGER_RISING | IRQF_ONESHOT,
 252                                  MICROREAD_I2C_DRIVER_NAME, phy);
 253         if (r) {
 254                 nfc_err(&client->dev, "Unable to register IRQ handler\n");
 255                 return r;
 256         }
 257
 258         r = microread_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
 259                             MICROREAD_I2C_FRAME_HEADROOM,
 260                             MICROREAD_I2C_FRAME_TAILROOM,
 261                             MICROREAD_I2C_LLC_MAX_PAYLOAD, &phy->hdev);
 262         if (r < 0)
 263                 goto err_irq;
 264
 265         nfc_info(&client->dev, "Probed\n");
 266
 267         return 0;
 268
 269 err_irq:
 270         free_irq(client->irq, phy);
 271
 272         return r;
 273 }
 274
 275 static int microread_i2c_remove(struct i2c_client *client)
 276 {
 277         struct microread_i2c_phy *phy = i2c_get_clientdata(client);
 278
 279         microread_remove(phy->hdev);
 280
 281         free_irq(client->irq, phy);
 282
 283         return 0;
 284 }
 285
 286 static const struct i2c_device_id microread_i2c_id[] = {
 287         { MICROREAD_I2C_DRIVER_NAME, 0},
 288         { }
 289 };
 290 MODULE_DEVICE_TABLE(i2c, microread_i2c_id);
 291
 292 static struct i2c_driver microread_i2c_driver = {
 293         .driver = {
 294                 .name = MICROREAD_I2C_DRIVER_NAME,
 295         },
 296         .probe          = microread_i2c_probe,
 297         .remove         = microread_i2c_remove,
 298         .id_table       = microread_i2c_id,
 299 };
 300
 301 module_i2c_driver(microread_i2c_driver);
 302
 303 MODULE_LICENSE("GPL");
 304 MODULE_DESCRIPTION(DRIVER_DESC);