drivers/nfc/microread/i2c.c

   1 /*
   2  * HCI based Driver for Inside Secure microread NFC Chip - i2c layer
   3  *
   4  * Copyright (C) 2013 Intel Corporation. All rights reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms and conditions of the GNU General Public License,
   8  * version 2, as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the
  17  * Free Software Foundation, Inc.,
  18  * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  19  */
  20
  21 #include <linux/module.h>
  22 #include <linux/i2c.h>
  23 #include <linux/delay.h>
  24 #include <linux/slab.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/gpio.h>
  27
  28 #include <linux/nfc.h>
  29 #include <net/nfc/hci.h>
  30 #include <net/nfc/llc.h>
  31
  32 #include "microread.h"
  33
  34 #define MICROREAD_I2C_DRIVER_NAME "microread"
  35
  36 #define MICROREAD_I2C_FRAME_HEADROOM 1
  37 #define MICROREAD_I2C_FRAME_TAILROOM 1
  38
  39 /* framing in HCI mode */
  40 #define MICROREAD_I2C_LLC_LEN           1
  41 #define MICROREAD_I2C_LLC_CRC           1
  42 #define MICROREAD_I2C_LLC_LEN_CRC       (MICROREAD_I2C_LLC_LEN + \
  43                                         MICROREAD_I2C_LLC_CRC)
  44 #define MICROREAD_I2C_LLC_MIN_SIZE      (1 + MICROREAD_I2C_LLC_LEN_CRC)
  45 #define MICROREAD_I2C_LLC_MAX_PAYLOAD   29
  46 #define MICROREAD_I2C_LLC_MAX_SIZE      (MICROREAD_I2C_LLC_LEN_CRC + 1 + \
  47                                         MICROREAD_I2C_LLC_MAX_PAYLOAD)
  48
  49 struct microread_i2c_phy {
  50         struct i2c_client *i2c_dev;
  51         struct nfc_hci_dev *hdev;
  52
  53         int irq;
  54
  55         int hard_fault;         /*
  56                                  * < 0 if hardware error occured (e.g. i2c err)
  57                                  * and prevents normal operation.
  58                                  */
  59 };
  60
  61 #define I2C_DUMP_SKB(info, skb)                                 \
  62 do {                                                            \
  63         pr_debug("%s:\n", info);                                \
  64         print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET, \
  65                        16, 1, (skb)->data, (skb)->len, 0);      \
  66 } while (0)
  67
  68 static void microread_i2c_add_len_crc(struct sk_buff *skb)
  69 {
  70         int i;
  71         u8 crc = 0;
  72         int len;
  73
  74         len = skb->len;
  75         *skb_push(skb, 1) = len;
  76
  77         for (i = 0; i < skb->len; i++)
  78                 crc = crc ^ skb->data[i];
  79
  80         *skb_put(skb, 1) = crc;
  81 }
  82
  83 static void microread_i2c_remove_len_crc(struct sk_buff *skb)
  84 {
  85         skb_pull(skb, MICROREAD_I2C_FRAME_HEADROOM);
  86         skb_trim(skb, MICROREAD_I2C_FRAME_TAILROOM);
  87 }
  88
  89 static int check_crc(struct sk_buff *skb)
  90 {
  91         int i;
  92         u8 crc = 0;
  93
  94         for (i = 0; i < skb->len - 1; i++)
  95                 crc = crc ^ skb->data[i];
  96
  97         if (crc != skb->data[skb->len-1]) {
  98                 pr_err(MICROREAD_I2C_DRIVER_NAME
  99                        ": CRC error 0x%x != 0x%x\n",
 100                        crc, skb->data[skb->len-1]);
 101
 102                 pr_info(DRIVER_DESC ": %s : BAD CRC\n", __func__);
 103
 104                 return -EPERM;
 105         }
 106
 107         return 0;
 108 }
 109
 110 static int microread_i2c_enable(void *phy_id)
 111 {
 112         return 0;
 113 }
 114
 115 static void microread_i2c_disable(void *phy_id)
 116 {
 117         return;
 118 }
 119
 120 static int microread_i2c_write(void *phy_id, struct sk_buff *skb)
 121 {
 122         int r;
 123         struct microread_i2c_phy *phy = phy_id;
 124         struct i2c_client *client = phy->i2c_dev;
 125
 126         if (phy->hard_fault != 0)
 127                 return phy->hard_fault;
 128
 129         usleep_range(3000, 6000);
 130
 131         microread_i2c_add_len_crc(skb);
 132
 133         I2C_DUMP_SKB("i2c frame written", skb);
 134
 135         r = i2c_master_send(client, skb->data, skb->len);
 136
 137         if (r == -EREMOTEIO) {  /* Retry, chip was in standby */
 138                 usleep_range(6000, 10000);
 139                 r = i2c_master_send(client, skb->data, skb->len);
 140         }
 141
 142         if (r >= 0) {
 143                 if (r != skb->len)
 144                         r = -EREMOTEIO;
 145                 else
 146                         r = 0;
 147         }
 148
 149         microread_i2c_remove_len_crc(skb);
 150
 151         return r;
 152 }
 153
 154
 155 static int microread_i2c_read(struct microread_i2c_phy *phy,
 156                               struct sk_buff **skb)
 157 {
 158         int r;
 159         u8 len;
 160         u8 tmp[MICROREAD_I2C_LLC_MAX_SIZE - 1];
 161         struct i2c_client *client = phy->i2c_dev;
 162
 163         pr_debug("%s\n", __func__);
 164
 165         r = i2c_master_recv(client, &len, 1);
 166         if (r != 1) {
 167                 dev_err(&client->dev, "cannot read len byte\n");
 168                 return -EREMOTEIO;
 169         }
 170
 171         if ((len < MICROREAD_I2C_LLC_MIN_SIZE) ||
 172             (len > MICROREAD_I2C_LLC_MAX_SIZE)) {
 173                 dev_err(&client->dev, "invalid len byte\n");
 174                 pr_err("invalid len byte\n");
 175                 r = -EBADMSG;
 176                 goto flush;
 177         }
 178
 179         *skb = alloc_skb(1 + len, GFP_KERNEL);
 180         if (*skb == NULL) {
 181                 r = -ENOMEM;
 182                 goto flush;
 183         }
 184
 185         *skb_put(*skb, 1) = len;
 186
 187         r = i2c_master_recv(client, skb_put(*skb, len), len);
 188         if (r != len) {
 189                 kfree_skb(*skb);
 190                 return -EREMOTEIO;
 191         }
 192
 193         I2C_DUMP_SKB("cc frame read", *skb);
 194
 195         r = check_crc(*skb);
 196         if (r != 0) {
 197                 kfree_skb(*skb);
 198                 r = -EBADMSG;
 199                 goto flush;
 200         }
 201
 202         skb_pull(*skb, 1);
 203         skb_trim(*skb, (*skb)->len - MICROREAD_I2C_FRAME_TAILROOM);
 204
 205         usleep_range(3000, 6000);
 206
 207         return 0;
 208
 209 flush:
 210         if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0)
 211                 r = -EREMOTEIO;
 212
 213         usleep_range(3000, 6000);
 214
 215         return r;
 216 }
 217
 218 static irqreturn_t microread_i2c_irq_thread_fn(int irq, void *phy_id)
 219 {
 220         struct microread_i2c_phy *phy = phy_id;
 221         struct i2c_client *client;
 222         struct sk_buff *skb = NULL;
 223         int r;
 224
 225         if (!phy || irq != phy->i2c_dev->irq) {
 226                 WARN_ON_ONCE(1);
 227                 return IRQ_NONE;
 228         }
 229
 230         client = phy->i2c_dev;
 231         dev_dbg(&client->dev, "IRQ\n");
 232
 233         if (phy->hard_fault != 0)
 234                 return IRQ_HANDLED;
 235
 236         r = microread_i2c_read(phy, &skb);
 237         if (r == -EREMOTEIO) {
 238                 phy->hard_fault = r;
 239
 240                 nfc_hci_recv_frame(phy->hdev, NULL);
 241
 242                 return IRQ_HANDLED;
 243         } else if ((r == -ENOMEM) || (r == -EBADMSG)) {
 244                 return IRQ_HANDLED;
 245         }
 246
 247         nfc_hci_recv_frame(phy->hdev, skb);
 248
 249         return IRQ_HANDLED;
 250 }
 251
 252 static struct nfc_phy_ops i2c_phy_ops = {
 253         .write = microread_i2c_write,
 254         .enable = microread_i2c_enable,
 255         .disable = microread_i2c_disable,
 256 };
 257
 258 static int microread_i2c_probe(struct i2c_client *client,
 259                                const struct i2c_device_id *id)
 260 {
 261         struct microread_i2c_phy *phy;
 262         struct microread_nfc_platform_data *pdata =
 263                 dev_get_platdata(&client->dev);
 264         int r;
 265
 266         dev_dbg(&client->dev, "client %p", client);
 267
 268         if (!pdata) {
 269                 dev_err(&client->dev, "client %p: missing platform data",
 270                         client);
 271                 return -EINVAL;
 272         }
 273
 274         phy = devm_kzalloc(&client->dev, sizeof(struct microread_i2c_phy),
 275                            GFP_KERNEL);
 276         if (!phy) {
 277                 dev_err(&client->dev, "Can't allocate microread phy");
 278                 return -ENOMEM;
 279         }
 280
 281         i2c_set_clientdata(client, phy);
 282         phy->i2c_dev = client;
 283
 284         r = request_threaded_irq(client->irq, NULL, microread_i2c_irq_thread_fn,
 285                                  IRQF_TRIGGER_RISING | IRQF_ONESHOT,
 286                                  MICROREAD_I2C_DRIVER_NAME, phy);
 287         if (r) {
 288                 dev_err(&client->dev, "Unable to register IRQ handler");
 289                 return r;
 290         }
 291
 292         r = microread_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
 293                             MICROREAD_I2C_FRAME_HEADROOM,
 294                             MICROREAD_I2C_FRAME_TAILROOM,
 295                             MICROREAD_I2C_LLC_MAX_PAYLOAD, &phy->hdev);
 296         if (r < 0)
 297                 goto err_irq;
 298
 299         dev_info(&client->dev, "Probed");
 300
 301         return 0;
 302
 303 err_irq:
 304         free_irq(client->irq, phy);
 305
 306         return r;
 307 }
 308
 309 static int microread_i2c_remove(struct i2c_client *client)
 310 {
 311         struct microread_i2c_phy *phy = i2c_get_clientdata(client);
 312
 313         dev_dbg(&client->dev, "%s\n", __func__);
 314
 315         microread_remove(phy->hdev);
 316
 317         free_irq(client->irq, phy);
 318
 319         return 0;
 320 }
 321
 322 static struct i2c_device_id microread_i2c_id[] = {
 323         { MICROREAD_I2C_DRIVER_NAME, 0},
 324         { }
 325 };
 326 MODULE_DEVICE_TABLE(i2c, microread_i2c_id);
 327
 328 static struct i2c_driver microread_i2c_driver = {
 329         .driver = {
 330                 .name = MICROREAD_I2C_DRIVER_NAME,
 331         },
 332         .probe          = microread_i2c_probe,
 333         .remove         = microread_i2c_remove,
 334         .id_table       = microread_i2c_id,
 335 };
 336
 337 module_i2c_driver(microread_i2c_driver);
 338
 339 MODULE_LICENSE("GPL");
 340 MODULE_DESCRIPTION(DRIVER_DESC);