drivers/nfc/pn544/i2c.c

   1 /*
   2  * I2C Link Layer for PN544 HCI based Driver
   3  *
   4  * Copyright (C) 2012  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/crc-ccitt.h>
  22 #include <linux/module.h>
  23 #include <linux/i2c.h>
  24 #include <linux/gpio.h>
  25 #include <linux/miscdevice.h>
  26 #include <linux/interrupt.h>
  27 #include <linux/delay.h>
  28
  29 #include <linux/platform_data/pn544.h>
  30
  31 #include <net/nfc/hci.h>
  32 #include <net/nfc/llc.h>
  33
  34 #include "pn544.h"
  35
  36 #define PN544_I2C_FRAME_HEADROOM 1
  37 #define PN544_I2C_FRAME_TAILROOM 2
  38
  39 /* framing in HCI mode */
  40 #define PN544_HCI_I2C_LLC_LEN           1
  41 #define PN544_HCI_I2C_LLC_CRC           2
  42 #define PN544_HCI_I2C_LLC_LEN_CRC       (PN544_HCI_I2C_LLC_LEN + \
  43                                          PN544_HCI_I2C_LLC_CRC)
  44 #define PN544_HCI_I2C_LLC_MIN_SIZE      (1 + PN544_HCI_I2C_LLC_LEN_CRC)
  45 #define PN544_HCI_I2C_LLC_MAX_PAYLOAD   29
  46 #define PN544_HCI_I2C_LLC_MAX_SIZE      (PN544_HCI_I2C_LLC_LEN_CRC + 1 + \
  47                                          PN544_HCI_I2C_LLC_MAX_PAYLOAD)
  48
  49 static struct i2c_device_id pn544_hci_i2c_id_table[] = {
  50         {"pn544", 0},
  51         {}
  52 };
  53
  54 MODULE_DEVICE_TABLE(i2c, pn544_hci_i2c_id_table);
  55
  56 #define PN544_HCI_I2C_DRIVER_NAME "pn544_hci_i2c"
  57
  58 struct pn544_i2c_phy {
  59         struct i2c_client *i2c_dev;
  60         struct nfc_hci_dev *hdev;
  61
  62         unsigned int gpio_en;
  63         unsigned int gpio_irq;
  64         unsigned int gpio_fw;
  65         unsigned int en_polarity;
  66
  67         int powered;
  68
  69         int hard_fault;         /*
  70                                  * < 0 if hardware error occured (e.g. i2c err)
  71                                  * and prevents normal operation.
  72                                  */
  73 };
  74
  75 #define I2C_DUMP_SKB(info, skb)                                 \
  76 do {                                                            \
  77         pr_debug("%s:\n", info);                                \
  78         print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET, \
  79                        16, 1, (skb)->data, (skb)->len, 0);      \
  80 } while (0)
  81
  82 static void pn544_hci_i2c_platform_init(struct pn544_i2c_phy *phy)
  83 {
  84         int polarity, retry, ret;
  85         char rset_cmd[] = { 0x05, 0xF9, 0x04, 0x00, 0xC3, 0xE5 };
  86         int count = sizeof(rset_cmd);
  87
  88         pr_info(DRIVER_DESC ": %s\n", __func__);
  89         dev_info(&phy->i2c_dev->dev, "Detecting nfc_en polarity\n");
  90
  91         /* Disable fw download */
  92         gpio_set_value(phy->gpio_fw, 0);
  93
  94         for (polarity = 0; polarity < 2; polarity++) {
  95                 phy->en_polarity = polarity;
  96                 retry = 3;
  97                 while (retry--) {
  98                         /* power off */
  99                         gpio_set_value(phy->gpio_en, !phy->en_polarity);
 100                         usleep_range(10000, 15000);
 101
 102                         /* power on */
 103                         gpio_set_value(phy->gpio_en, phy->en_polarity);
 104                         usleep_range(10000, 15000);
 105
 106                         /* send reset */
 107                         dev_dbg(&phy->i2c_dev->dev, "Sending reset cmd\n");
 108                         ret = i2c_master_send(phy->i2c_dev, rset_cmd, count);
 109                         if (ret == count) {
 110                                 dev_info(&phy->i2c_dev->dev,
 111                                          "nfc_en polarity : active %s\n",
 112                                          (polarity == 0 ? "low" : "high"));
 113                                 goto out;
 114                         }
 115                 }
 116         }
 117
 118         dev_err(&phy->i2c_dev->dev,
 119                 "Could not detect nfc_en polarity, fallback to active high\n");
 120
 121 out:
 122         gpio_set_value(phy->gpio_en, !phy->en_polarity);
 123 }
 124
 125 static int pn544_hci_i2c_enable(void *phy_id)
 126 {
 127         struct pn544_i2c_phy *phy = phy_id;
 128
 129         pr_info(DRIVER_DESC ": %s\n", __func__);
 130
 131         gpio_set_value(phy->gpio_fw, 0);
 132         gpio_set_value(phy->gpio_en, phy->en_polarity);
 133         usleep_range(10000, 15000);
 134
 135         phy->powered = 1;
 136
 137         return 0;
 138 }
 139
 140 static void pn544_hci_i2c_disable(void *phy_id)
 141 {
 142         struct pn544_i2c_phy *phy = phy_id;
 143
 144         pr_info(DRIVER_DESC ": %s\n", __func__);
 145
 146         gpio_set_value(phy->gpio_fw, 0);
 147         gpio_set_value(phy->gpio_en, !phy->en_polarity);
 148         usleep_range(10000, 15000);
 149
 150         gpio_set_value(phy->gpio_en, phy->en_polarity);
 151         usleep_range(10000, 15000);
 152
 153         gpio_set_value(phy->gpio_en, !phy->en_polarity);
 154         usleep_range(10000, 15000);
 155
 156         phy->powered = 0;
 157 }
 158
 159 static void pn544_hci_i2c_add_len_crc(struct sk_buff *skb)
 160 {
 161         u16 crc;
 162         int len;
 163
 164         len = skb->len + 2;
 165         *skb_push(skb, 1) = len;
 166
 167         crc = crc_ccitt(0xffff, skb->data, skb->len);
 168         crc = ~crc;
 169         *skb_put(skb, 1) = crc & 0xff;
 170         *skb_put(skb, 1) = crc >> 8;
 171 }
 172
 173 static void pn544_hci_i2c_remove_len_crc(struct sk_buff *skb)
 174 {
 175         skb_pull(skb, PN544_I2C_FRAME_HEADROOM);
 176         skb_trim(skb, PN544_I2C_FRAME_TAILROOM);
 177 }
 178
 179 /*
 180  * Writing a frame must not return the number of written bytes.
 181  * It must return either zero for success, or <0 for error.
 182  * In addition, it must not alter the skb
 183  */
 184 static int pn544_hci_i2c_write(void *phy_id, struct sk_buff *skb)
 185 {
 186         int r;
 187         struct pn544_i2c_phy *phy = phy_id;
 188         struct i2c_client *client = phy->i2c_dev;
 189
 190         if (phy->hard_fault != 0)
 191                 return phy->hard_fault;
 192
 193         usleep_range(3000, 6000);
 194
 195         pn544_hci_i2c_add_len_crc(skb);
 196
 197         I2C_DUMP_SKB("i2c frame written", skb);
 198
 199         r = i2c_master_send(client, skb->data, skb->len);
 200
 201         if (r == -EREMOTEIO) {  /* Retry, chip was in standby */
 202                 usleep_range(6000, 10000);
 203                 r = i2c_master_send(client, skb->data, skb->len);
 204         }
 205
 206         if (r >= 0) {
 207                 if (r != skb->len)
 208                         r = -EREMOTEIO;
 209                 else
 210                         r = 0;
 211         }
 212
 213         pn544_hci_i2c_remove_len_crc(skb);
 214
 215         return r;
 216 }
 217
 218 static int check_crc(u8 *buf, int buflen)
 219 {
 220         int len;
 221         u16 crc;
 222
 223         len = buf[0] + 1;
 224         crc = crc_ccitt(0xffff, buf, len - 2);
 225         crc = ~crc;
 226
 227         if (buf[len - 2] != (crc & 0xff) || buf[len - 1] != (crc >> 8)) {
 228                 pr_err(PN544_HCI_I2C_DRIVER_NAME
 229                        ": CRC error 0x%x != 0x%x 0x%x\n",
 230                        crc, buf[len - 1], buf[len - 2]);
 231
 232                 pr_info(DRIVER_DESC ": %s : BAD CRC\n", __func__);
 233                 print_hex_dump(KERN_DEBUG, "crc: ", DUMP_PREFIX_NONE,
 234                                16, 2, buf, buflen, false);
 235                 return -EPERM;
 236         }
 237         return 0;
 238 }
 239
 240 /*
 241  * Reads an shdlc frame and returns it in a newly allocated sk_buff. Guarantees
 242  * that i2c bus will be flushed and that next read will start on a new frame.
 243  * returned skb contains only LLC header and payload.
 244  * returns:
 245  * -EREMOTEIO : i2c read error (fatal)
 246  * -EBADMSG : frame was incorrect and discarded
 247  * -ENOMEM : cannot allocate skb, frame dropped
 248  */
 249 static int pn544_hci_i2c_read(struct pn544_i2c_phy *phy, struct sk_buff **skb)
 250 {
 251         int r;
 252         u8 len;
 253         u8 tmp[PN544_HCI_I2C_LLC_MAX_SIZE - 1];
 254         struct i2c_client *client = phy->i2c_dev;
 255
 256         r = i2c_master_recv(client, &len, 1);
 257         if (r != 1) {
 258                 dev_err(&client->dev, "cannot read len byte\n");
 259                 return -EREMOTEIO;
 260         }
 261
 262         if ((len < (PN544_HCI_I2C_LLC_MIN_SIZE - 1)) ||
 263             (len > (PN544_HCI_I2C_LLC_MAX_SIZE - 1))) {
 264                 dev_err(&client->dev, "invalid len byte\n");
 265                 r = -EBADMSG;
 266                 goto flush;
 267         }
 268
 269         *skb = alloc_skb(1 + len, GFP_KERNEL);
 270         if (*skb == NULL) {
 271                 r = -ENOMEM;
 272                 goto flush;
 273         }
 274
 275         *skb_put(*skb, 1) = len;
 276
 277         r = i2c_master_recv(client, skb_put(*skb, len), len);
 278         if (r != len) {
 279                 kfree_skb(*skb);
 280                 return -EREMOTEIO;
 281         }
 282
 283         I2C_DUMP_SKB("i2c frame read", *skb);
 284
 285         r = check_crc((*skb)->data, (*skb)->len);
 286         if (r != 0) {
 287                 kfree_skb(*skb);
 288                 r = -EBADMSG;
 289                 goto flush;
 290         }
 291
 292         skb_pull(*skb, 1);
 293         skb_trim(*skb, (*skb)->len - 2);
 294
 295         usleep_range(3000, 6000);
 296
 297         return 0;
 298
 299 flush:
 300         if (i2c_master_recv(client, tmp, sizeof(tmp)) < 0)
 301                 r = -EREMOTEIO;
 302
 303         usleep_range(3000, 6000);
 304
 305         return r;
 306 }
 307
 308 /*
 309  * Reads an shdlc frame from the chip. This is not as straightforward as it
 310  * seems. There are cases where we could loose the frame start synchronization.
 311  * The frame format is len-data-crc, and corruption can occur anywhere while
 312  * transiting on i2c bus, such that we could read an invalid len.
 313  * In order to recover synchronization with the next frame, we must be sure
 314  * to read the real amount of data without using the len byte. We do this by
 315  * assuming the following:
 316  * - the chip will always present only one single complete frame on the bus
 317  *   before triggering the interrupt
 318  * - the chip will not present a new frame until we have completely read
 319  *   the previous one (or until we have handled the interrupt).
 320  * The tricky case is when we read a corrupted len that is less than the real
 321  * len. We must detect this here in order to determine that we need to flush
 322  * the bus. This is the reason why we check the crc here.
 323  */
 324 static irqreturn_t pn544_hci_i2c_irq_thread_fn(int irq, void *phy_id)
 325 {
 326         struct pn544_i2c_phy *phy = phy_id;
 327         struct i2c_client *client;
 328         struct sk_buff *skb = NULL;
 329         int r;
 330
 331         if (!phy || irq != phy->i2c_dev->irq) {
 332                 WARN_ON_ONCE(1);
 333                 return IRQ_NONE;
 334         }
 335
 336         client = phy->i2c_dev;
 337         dev_dbg(&client->dev, "IRQ\n");
 338
 339         if (phy->hard_fault != 0)
 340                 return IRQ_HANDLED;
 341
 342         r = pn544_hci_i2c_read(phy, &skb);
 343         if (r == -EREMOTEIO) {
 344                 phy->hard_fault = r;
 345
 346                 nfc_hci_recv_frame(phy->hdev, NULL);
 347
 348                 return IRQ_HANDLED;
 349         } else if ((r == -ENOMEM) || (r == -EBADMSG)) {
 350                 return IRQ_HANDLED;
 351         }
 352
 353         nfc_hci_recv_frame(phy->hdev, skb);
 354
 355         return IRQ_HANDLED;
 356 }
 357
 358 static struct nfc_phy_ops i2c_phy_ops = {
 359         .write = pn544_hci_i2c_write,
 360         .enable = pn544_hci_i2c_enable,
 361         .disable = pn544_hci_i2c_disable,
 362 };
 363
 364 static int __devinit pn544_hci_i2c_probe(struct i2c_client *client,
 365                                      const struct i2c_device_id *id)
 366 {
 367         struct pn544_i2c_phy *phy;
 368         struct pn544_nfc_platform_data *pdata;
 369         int r = 0;
 370
 371         dev_dbg(&client->dev, "%s\n", __func__);
 372         dev_dbg(&client->dev, "IRQ: %d\n", client->irq);
 373
 374         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
 375                 dev_err(&client->dev, "Need I2C_FUNC_I2C\n");
 376                 return -ENODEV;
 377         }
 378
 379         phy = kzalloc(sizeof(struct pn544_i2c_phy), GFP_KERNEL);
 380         if (!phy) {
 381                 dev_err(&client->dev,
 382                         "Cannot allocate memory for pn544 i2c phy.\n");
 383                 r = -ENOMEM;
 384                 goto err_phy_alloc;
 385         }
 386
 387         phy->i2c_dev = client;
 388         i2c_set_clientdata(client, phy);
 389
 390         pdata = client->dev.platform_data;
 391         if (pdata == NULL) {
 392                 dev_err(&client->dev, "No platform data\n");
 393                 r = -EINVAL;
 394                 goto err_pdata;
 395         }
 396
 397         if (pdata->request_resources == NULL) {
 398                 dev_err(&client->dev, "request_resources() missing\n");
 399                 r = -EINVAL;
 400                 goto err_pdata;
 401         }
 402
 403         r = pdata->request_resources(client);
 404         if (r) {
 405                 dev_err(&client->dev, "Cannot get platform resources\n");
 406                 goto err_pdata;
 407         }
 408
 409         phy->gpio_en = pdata->get_gpio(NFC_GPIO_ENABLE);
 410         phy->gpio_fw = pdata->get_gpio(NFC_GPIO_FW_RESET);
 411         phy->gpio_irq = pdata->get_gpio(NFC_GPIO_IRQ);
 412
 413         pn544_hci_i2c_platform_init(phy);
 414
 415         r = request_threaded_irq(client->irq, NULL, pn544_hci_i2c_irq_thread_fn,
 416                                  IRQF_TRIGGER_RISING | IRQF_ONESHOT,
 417                                  PN544_HCI_I2C_DRIVER_NAME, phy);
 418         if (r < 0) {
 419                 dev_err(&client->dev, "Unable to register IRQ handler\n");
 420                 goto err_rti;
 421         }
 422
 423         r = pn544_hci_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME,
 424                             PN544_I2C_FRAME_HEADROOM, PN544_I2C_FRAME_TAILROOM,
 425                             PN544_HCI_I2C_LLC_MAX_PAYLOAD, &phy->hdev);
 426         if (r < 0)
 427                 goto err_hci;
 428
 429         return 0;
 430
 431 err_hci:
 432         free_irq(client->irq, phy);
 433
 434 err_rti:
 435         if (pdata->free_resources != NULL)
 436                 pdata->free_resources();
 437
 438 err_pdata:
 439         kfree(phy);
 440
 441 err_phy_alloc:
 442         return r;
 443 }
 444
 445 static __devexit int pn544_hci_i2c_remove(struct i2c_client *client)
 446 {
 447         struct pn544_i2c_phy *phy = i2c_get_clientdata(client);
 448         struct pn544_nfc_platform_data *pdata = client->dev.platform_data;
 449
 450         dev_dbg(&client->dev, "%s\n", __func__);
 451
 452         pn544_hci_remove(phy->hdev);
 453
 454         if (phy->powered)
 455                 pn544_hci_i2c_disable(phy);
 456
 457         free_irq(client->irq, phy);
 458         if (pdata->free_resources)
 459                 pdata->free_resources();
 460
 461         kfree(phy);
 462
 463         return 0;
 464 }
 465
 466 static struct i2c_driver pn544_hci_i2c_driver = {
 467         .driver = {
 468                    .name = PN544_HCI_I2C_DRIVER_NAME,
 469                   },
 470         .probe = pn544_hci_i2c_probe,
 471         .id_table = pn544_hci_i2c_id_table,
 472         .remove = __devexit_p(pn544_hci_i2c_remove),
 473 };
 474
 475 static int __init pn544_hci_i2c_init(void)
 476 {
 477         int r;
 478
 479         pr_debug(DRIVER_DESC ": %s\n", __func__);
 480
 481         r = i2c_add_driver(&pn544_hci_i2c_driver);
 482         if (r) {
 483                 pr_err(PN544_HCI_I2C_DRIVER_NAME
 484                        ": driver registration failed\n");
 485                 return r;
 486         }
 487
 488         return 0;
 489 }
 490
 491 static void __exit pn544_hci_i2c_exit(void)
 492 {
 493         i2c_del_driver(&pn544_hci_i2c_driver);
 494 }
 495
 496 module_init(pn544_hci_i2c_init);
 497 module_exit(pn544_hci_i2c_exit);
 498
 499 MODULE_LICENSE("GPL");
 500 MODULE_DESCRIPTION(DRIVER_DESC);