1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * I2C Link Layer for ST21NFCA HCI based Driver 4 * Copyright (C) 2014 STMicroelectronics SAS. All rights reserved. 5 */ 6 7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 8 9 #include <linux/crc-ccitt.h> 10 #include <linux/module.h> 11 #include <linux/i2c.h> 12 #include <linux/gpio/consumer.h> 13 #include <linux/of_irq.h> 14 #include <linux/of_gpio.h> 15 #include <linux/acpi.h> 16 #include <linux/interrupt.h> 17 #include <linux/delay.h> 18 #include <linux/nfc.h> 19 #include <linux/firmware.h> 20 21 #include <net/nfc/hci.h> 22 #include <net/nfc/llc.h> 23 #include <net/nfc/nfc.h> 24 25 #include "st21nfca.h" 26 27 /* 28 * Every frame starts with ST21NFCA_SOF_EOF and ends with ST21NFCA_SOF_EOF. 29 * Because ST21NFCA_SOF_EOF is a possible data value, there is a mecanism 30 * called byte stuffing has been introduced. 31 * 32 * if byte == ST21NFCA_SOF_EOF or ST21NFCA_ESCAPE_BYTE_STUFFING 33 * - insert ST21NFCA_ESCAPE_BYTE_STUFFING (escape byte) 34 * - xor byte with ST21NFCA_BYTE_STUFFING_MASK 35 */ 36 #define ST21NFCA_SOF_EOF 0x7e 37 #define ST21NFCA_BYTE_STUFFING_MASK 0x20 38 #define ST21NFCA_ESCAPE_BYTE_STUFFING 0x7d 39 40 /* SOF + 00 */ 41 #define ST21NFCA_FRAME_HEADROOM 2 42 43 /* 2 bytes crc + EOF */ 44 #define ST21NFCA_FRAME_TAILROOM 3 45 #define IS_START_OF_FRAME(buf) (buf[0] == ST21NFCA_SOF_EOF && \ 46 buf[1] == 0) 47 48 #define ST21NFCA_HCI_DRIVER_NAME "st21nfca_hci" 49 #define ST21NFCA_HCI_I2C_DRIVER_NAME "st21nfca_hci_i2c" 50 51 struct st21nfca_i2c_phy { 52 struct i2c_client *i2c_dev; 53 struct nfc_hci_dev *hdev; 54 55 struct gpio_desc *gpiod_ena; 56 struct st21nfca_se_status se_status; 57 58 struct sk_buff *pending_skb; 59 int current_read_len; 60 /* 61 * crc might have fail because i2c macro 62 * is disable due to other interface activity 63 */ 64 int crc_trials; 65 66 int powered; 67 int run_mode; 68 69 /* 70 * < 0 if hardware error occured (e.g. i2c err) 71 * and prevents normal operation. 72 */ 73 int hard_fault; 74 struct mutex phy_lock; 75 }; 76 77 static const u8 len_seq[] = { 16, 24, 12, 29 }; 78 static const u16 wait_tab[] = { 2, 3, 5, 15, 20, 40}; 79 80 #define I2C_DUMP_SKB(info, skb) \ 81 do { \ 82 pr_debug("%s:\n", info); \ 83 print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET, \ 84 16, 1, (skb)->data, (skb)->len, 0); \ 85 } while (0) 86 87 /* 88 * In order to get the CLF in a known state we generate an internal reboot 89 * using a proprietary command. 90 * Once the reboot is completed, we expect to receive a ST21NFCA_SOF_EOF 91 * fill buffer. 92 */ 93 static int st21nfca_hci_platform_init(struct st21nfca_i2c_phy *phy) 94 { 95 u16 wait_reboot[] = { 50, 300, 1000 }; 96 char reboot_cmd[] = { 0x7E, 0x66, 0x48, 0xF6, 0x7E }; 97 u8 tmp[ST21NFCA_HCI_LLC_MAX_SIZE]; 98 int i, r = -1; 99 100 for (i = 0; i < ARRAY_SIZE(wait_reboot) && r < 0; i++) { 101 r = i2c_master_send(phy->i2c_dev, reboot_cmd, 102 sizeof(reboot_cmd)); 103 if (r < 0) 104 msleep(wait_reboot[i]); 105 } 106 if (r < 0) 107 return r; 108 109 /* CLF is spending about 20ms to do an internal reboot */ 110 msleep(20); 111 r = -1; 112 for (i = 0; i < ARRAY_SIZE(wait_reboot) && r < 0; i++) { 113 r = i2c_master_recv(phy->i2c_dev, tmp, 114 ST21NFCA_HCI_LLC_MAX_SIZE); 115 if (r < 0) 116 msleep(wait_reboot[i]); 117 } 118 if (r < 0) 119 return r; 120 121 for (i = 0; i < ST21NFCA_HCI_LLC_MAX_SIZE && 122 tmp[i] == ST21NFCA_SOF_EOF; i++) 123 ; 124 125 if (r != ST21NFCA_HCI_LLC_MAX_SIZE) 126 return -ENODEV; 127 128 usleep_range(1000, 1500); 129 return 0; 130 } 131 132 static int st21nfca_hci_i2c_enable(void *phy_id) 133 { 134 struct st21nfca_i2c_phy *phy = phy_id; 135 136 gpiod_set_value(phy->gpiod_ena, 1); 137 phy->powered = 1; 138 phy->run_mode = ST21NFCA_HCI_MODE; 139 140 usleep_range(10000, 15000); 141 142 return 0; 143 } 144 145 static void st21nfca_hci_i2c_disable(void *phy_id) 146 { 147 struct st21nfca_i2c_phy *phy = phy_id; 148 149 gpiod_set_value(phy->gpiod_ena, 0); 150 151 phy->powered = 0; 152 } 153 154 static void st21nfca_hci_add_len_crc(struct sk_buff *skb) 155 { 156 u16 crc; 157 u8 tmp; 158 159 *(u8 *)skb_push(skb, 1) = 0; 160 161 crc = crc_ccitt(0xffff, skb->data, skb->len); 162 crc = ~crc; 163 164 tmp = crc & 0x00ff; 165 skb_put_u8(skb, tmp); 166 167 tmp = (crc >> 8) & 0x00ff; 168 skb_put_u8(skb, tmp); 169 } 170 171 static void st21nfca_hci_remove_len_crc(struct sk_buff *skb) 172 { 173 skb_pull(skb, ST21NFCA_FRAME_HEADROOM); 174 skb_trim(skb, skb->len - ST21NFCA_FRAME_TAILROOM); 175 } 176 177 /* 178 * Writing a frame must not return the number of written bytes. 179 * It must return either zero for success, or <0 for error. 180 * In addition, it must not alter the skb 181 */ 182 static int st21nfca_hci_i2c_write(void *phy_id, struct sk_buff *skb) 183 { 184 int r = -1, i, j; 185 struct st21nfca_i2c_phy *phy = phy_id; 186 struct i2c_client *client = phy->i2c_dev; 187 u8 tmp[ST21NFCA_HCI_LLC_MAX_SIZE * 2]; 188 189 I2C_DUMP_SKB("st21nfca_hci_i2c_write", skb); 190 191 if (phy->hard_fault != 0) 192 return phy->hard_fault; 193 194 /* 195 * Compute CRC before byte stuffing computation on frame 196 * Note st21nfca_hci_add_len_crc is doing a byte stuffing 197 * on its own value 198 */ 199 st21nfca_hci_add_len_crc(skb); 200 201 /* add ST21NFCA_SOF_EOF on tail */ 202 skb_put_u8(skb, ST21NFCA_SOF_EOF); 203 /* add ST21NFCA_SOF_EOF on head */ 204 *(u8 *)skb_push(skb, 1) = ST21NFCA_SOF_EOF; 205 206 /* 207 * Compute byte stuffing 208 * if byte == ST21NFCA_SOF_EOF or ST21NFCA_ESCAPE_BYTE_STUFFING 209 * insert ST21NFCA_ESCAPE_BYTE_STUFFING (escape byte) 210 * xor byte with ST21NFCA_BYTE_STUFFING_MASK 211 */ 212 tmp[0] = skb->data[0]; 213 for (i = 1, j = 1; i < skb->len - 1; i++, j++) { 214 if (skb->data[i] == ST21NFCA_SOF_EOF 215 || skb->data[i] == ST21NFCA_ESCAPE_BYTE_STUFFING) { 216 tmp[j] = ST21NFCA_ESCAPE_BYTE_STUFFING; 217 j++; 218 tmp[j] = skb->data[i] ^ ST21NFCA_BYTE_STUFFING_MASK; 219 } else { 220 tmp[j] = skb->data[i]; 221 } 222 } 223 tmp[j] = skb->data[i]; 224 j++; 225 226 /* 227 * Manage sleep mode 228 * Try 3 times to send data with delay between each 229 */ 230 mutex_lock(&phy->phy_lock); 231 for (i = 0; i < ARRAY_SIZE(wait_tab) && r < 0; i++) { 232 r = i2c_master_send(client, tmp, j); 233 if (r < 0) 234 msleep(wait_tab[i]); 235 } 236 mutex_unlock(&phy->phy_lock); 237 238 if (r >= 0) { 239 if (r != j) 240 r = -EREMOTEIO; 241 else 242 r = 0; 243 } 244 245 st21nfca_hci_remove_len_crc(skb); 246 247 return r; 248 } 249 250 static int get_frame_size(u8 *buf, int buflen) 251 { 252 int len = 0; 253 254 if (buf[len + 1] == ST21NFCA_SOF_EOF) 255 return 0; 256 257 for (len = 1; len < buflen && buf[len] != ST21NFCA_SOF_EOF; len++) 258 ; 259 260 return len; 261 } 262 263 static int check_crc(u8 *buf, int buflen) 264 { 265 u16 crc; 266 267 crc = crc_ccitt(0xffff, buf, buflen - 2); 268 crc = ~crc; 269 270 if (buf[buflen - 2] != (crc & 0xff) || buf[buflen - 1] != (crc >> 8)) { 271 pr_err(ST21NFCA_HCI_DRIVER_NAME 272 ": CRC error 0x%x != 0x%x 0x%x\n", crc, buf[buflen - 1], 273 buf[buflen - 2]); 274 275 pr_info(DRIVER_DESC ": %s : BAD CRC\n", __func__); 276 print_hex_dump(KERN_DEBUG, "crc: ", DUMP_PREFIX_NONE, 277 16, 2, buf, buflen, false); 278 return -EPERM; 279 } 280 return 0; 281 } 282 283 /* 284 * Prepare received data for upper layer. 285 * Received data include byte stuffing, crc and sof/eof 286 * which is not usable by hci part. 287 * returns: 288 * frame size without sof/eof, header and byte stuffing 289 * -EBADMSG : frame was incorrect and discarded 290 */ 291 static int st21nfca_hci_i2c_repack(struct sk_buff *skb) 292 { 293 int i, j, r, size; 294 295 if (skb->len < 1 || (skb->len > 1 && skb->data[1] != 0)) 296 return -EBADMSG; 297 298 size = get_frame_size(skb->data, skb->len); 299 if (size > 0) { 300 skb_trim(skb, size); 301 /* remove ST21NFCA byte stuffing for upper layer */ 302 for (i = 1, j = 0; i < skb->len; i++) { 303 if (skb->data[i + j] == 304 (u8) ST21NFCA_ESCAPE_BYTE_STUFFING) { 305 skb->data[i] = skb->data[i + j + 1] 306 | ST21NFCA_BYTE_STUFFING_MASK; 307 i++; 308 j++; 309 } 310 skb->data[i] = skb->data[i + j]; 311 } 312 /* remove byte stuffing useless byte */ 313 skb_trim(skb, i - j); 314 /* remove ST21NFCA_SOF_EOF from head */ 315 skb_pull(skb, 1); 316 317 r = check_crc(skb->data, skb->len); 318 if (r != 0) 319 return -EBADMSG; 320 321 /* remove headbyte */ 322 skb_pull(skb, 1); 323 /* remove crc. Byte Stuffing is already removed here */ 324 skb_trim(skb, skb->len - 2); 325 return skb->len; 326 } 327 return 0; 328 } 329 330 /* 331 * Reads an shdlc frame and returns it in a newly allocated sk_buff. Guarantees 332 * that i2c bus will be flushed and that next read will start on a new frame. 333 * returned skb contains only LLC header and payload. 334 * returns: 335 * frame size : if received frame is complete (find ST21NFCA_SOF_EOF at 336 * end of read) 337 * -EAGAIN : if received frame is incomplete (not find ST21NFCA_SOF_EOF 338 * at end of read) 339 * -EREMOTEIO : i2c read error (fatal) 340 * -EBADMSG : frame was incorrect and discarded 341 * (value returned from st21nfca_hci_i2c_repack) 342 * -EIO : if no ST21NFCA_SOF_EOF is found after reaching 343 * the read length end sequence 344 */ 345 static int st21nfca_hci_i2c_read(struct st21nfca_i2c_phy *phy, 346 struct sk_buff *skb) 347 { 348 int r, i; 349 u8 len; 350 u8 buf[ST21NFCA_HCI_LLC_MAX_PAYLOAD]; 351 struct i2c_client *client = phy->i2c_dev; 352 353 if (phy->current_read_len < ARRAY_SIZE(len_seq)) { 354 len = len_seq[phy->current_read_len]; 355 356 /* 357 * Add retry mecanism 358 * Operation on I2C interface may fail in case of operation on 359 * RF or SWP interface 360 */ 361 r = 0; 362 mutex_lock(&phy->phy_lock); 363 for (i = 0; i < ARRAY_SIZE(wait_tab) && r <= 0; i++) { 364 r = i2c_master_recv(client, buf, len); 365 if (r < 0) 366 msleep(wait_tab[i]); 367 } 368 mutex_unlock(&phy->phy_lock); 369 370 if (r != len) { 371 phy->current_read_len = 0; 372 return -EREMOTEIO; 373 } 374 375 /* 376 * The first read sequence does not start with SOF. 377 * Data is corrupeted so we drop it. 378 */ 379 if (!phy->current_read_len && !IS_START_OF_FRAME(buf)) { 380 skb_trim(skb, 0); 381 phy->current_read_len = 0; 382 return -EIO; 383 } else if (phy->current_read_len && IS_START_OF_FRAME(buf)) { 384 /* 385 * Previous frame transmission was interrupted and 386 * the frame got repeated. 387 * Received frame start with ST21NFCA_SOF_EOF + 00. 388 */ 389 skb_trim(skb, 0); 390 phy->current_read_len = 0; 391 } 392 393 skb_put_data(skb, buf, len); 394 395 if (skb->data[skb->len - 1] == ST21NFCA_SOF_EOF) { 396 phy->current_read_len = 0; 397 return st21nfca_hci_i2c_repack(skb); 398 } 399 phy->current_read_len++; 400 return -EAGAIN; 401 } 402 return -EIO; 403 } 404 405 /* 406 * Reads an shdlc frame from the chip. This is not as straightforward as it 407 * seems. The frame format is data-crc, and corruption can occur anywhere 408 * while transiting on i2c bus, such that we could read an invalid data. 409 * The tricky case is when we read a corrupted data or crc. We must detect 410 * this here in order to determine that data can be transmitted to the hci 411 * core. This is the reason why we check the crc here. 412 * The CLF will repeat a frame until we send a RR on that frame. 413 * 414 * On ST21NFCA, IRQ goes in idle when read starts. As no size information are 415 * available in the incoming data, other IRQ might come. Every IRQ will trigger 416 * a read sequence with different length and will fill the current frame. 417 * The reception is complete once we reach a ST21NFCA_SOF_EOF. 418 */ 419 static irqreturn_t st21nfca_hci_irq_thread_fn(int irq, void *phy_id) 420 { 421 struct st21nfca_i2c_phy *phy = phy_id; 422 423 int r; 424 425 if (!phy || irq != phy->i2c_dev->irq) { 426 WARN_ON_ONCE(1); 427 return IRQ_NONE; 428 } 429 430 if (phy->hard_fault != 0) 431 return IRQ_HANDLED; 432 433 r = st21nfca_hci_i2c_read(phy, phy->pending_skb); 434 if (r == -EREMOTEIO) { 435 phy->hard_fault = r; 436 437 nfc_hci_recv_frame(phy->hdev, NULL); 438 439 return IRQ_HANDLED; 440 } else if (r == -EAGAIN || r == -EIO) { 441 return IRQ_HANDLED; 442 } else if (r == -EBADMSG && phy->crc_trials < ARRAY_SIZE(wait_tab)) { 443 /* 444 * With ST21NFCA, only one interface (I2C, RF or SWP) 445 * may be active at a time. 446 * Having incorrect crc is usually due to i2c macrocell 447 * deactivation in the middle of a transmission. 448 * It may generate corrupted data on i2c. 449 * We give sometime to get i2c back. 450 * The complete frame will be repeated. 451 */ 452 msleep(wait_tab[phy->crc_trials]); 453 phy->crc_trials++; 454 phy->current_read_len = 0; 455 kfree_skb(phy->pending_skb); 456 } else if (r > 0) { 457 /* 458 * We succeeded to read data from the CLF and 459 * data is valid. 460 * Reset counter. 461 */ 462 nfc_hci_recv_frame(phy->hdev, phy->pending_skb); 463 phy->crc_trials = 0; 464 } else { 465 kfree_skb(phy->pending_skb); 466 } 467 468 phy->pending_skb = alloc_skb(ST21NFCA_HCI_LLC_MAX_SIZE * 2, GFP_KERNEL); 469 if (phy->pending_skb == NULL) { 470 phy->hard_fault = -ENOMEM; 471 nfc_hci_recv_frame(phy->hdev, NULL); 472 } 473 474 return IRQ_HANDLED; 475 } 476 477 static const struct nfc_phy_ops i2c_phy_ops = { 478 .write = st21nfca_hci_i2c_write, 479 .enable = st21nfca_hci_i2c_enable, 480 .disable = st21nfca_hci_i2c_disable, 481 }; 482 483 static const struct acpi_gpio_params enable_gpios = { 1, 0, false }; 484 485 static const struct acpi_gpio_mapping acpi_st21nfca_gpios[] = { 486 { "enable-gpios", &enable_gpios, 1 }, 487 {}, 488 }; 489 490 static int st21nfca_hci_i2c_probe(struct i2c_client *client) 491 { 492 struct device *dev = &client->dev; 493 struct st21nfca_i2c_phy *phy; 494 int r; 495 496 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) { 497 nfc_err(&client->dev, "Need I2C_FUNC_I2C\n"); 498 return -ENODEV; 499 } 500 501 phy = devm_kzalloc(&client->dev, sizeof(struct st21nfca_i2c_phy), 502 GFP_KERNEL); 503 if (!phy) 504 return -ENOMEM; 505 506 phy->i2c_dev = client; 507 phy->pending_skb = alloc_skb(ST21NFCA_HCI_LLC_MAX_SIZE * 2, GFP_KERNEL); 508 if (phy->pending_skb == NULL) 509 return -ENOMEM; 510 511 phy->current_read_len = 0; 512 phy->crc_trials = 0; 513 mutex_init(&phy->phy_lock); 514 i2c_set_clientdata(client, phy); 515 516 r = devm_acpi_dev_add_driver_gpios(dev, acpi_st21nfca_gpios); 517 if (r) 518 dev_dbg(dev, "Unable to add GPIO mapping table\n"); 519 520 /* Get EN GPIO from resource provider */ 521 phy->gpiod_ena = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW); 522 if (IS_ERR(phy->gpiod_ena)) { 523 nfc_err(dev, "Unable to get ENABLE GPIO\n"); 524 r = PTR_ERR(phy->gpiod_ena); 525 goto out_free; 526 } 527 528 phy->se_status.is_ese_present = 529 device_property_read_bool(&client->dev, "ese-present"); 530 phy->se_status.is_uicc_present = 531 device_property_read_bool(&client->dev, "uicc-present"); 532 533 r = st21nfca_hci_platform_init(phy); 534 if (r < 0) { 535 nfc_err(&client->dev, "Unable to reboot st21nfca\n"); 536 goto out_free; 537 } 538 539 r = devm_request_threaded_irq(&client->dev, client->irq, NULL, 540 st21nfca_hci_irq_thread_fn, 541 IRQF_ONESHOT, 542 ST21NFCA_HCI_DRIVER_NAME, phy); 543 if (r < 0) { 544 nfc_err(&client->dev, "Unable to register IRQ handler\n"); 545 goto out_free; 546 } 547 548 r = st21nfca_hci_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME, 549 ST21NFCA_FRAME_HEADROOM, 550 ST21NFCA_FRAME_TAILROOM, 551 ST21NFCA_HCI_LLC_MAX_PAYLOAD, 552 &phy->hdev, 553 &phy->se_status); 554 if (r) 555 goto out_free; 556 557 return 0; 558 559 out_free: 560 kfree_skb(phy->pending_skb); 561 return r; 562 } 563 564 static void st21nfca_hci_i2c_remove(struct i2c_client *client) 565 { 566 struct st21nfca_i2c_phy *phy = i2c_get_clientdata(client); 567 568 st21nfca_hci_remove(phy->hdev); 569 570 if (phy->powered) 571 st21nfca_hci_i2c_disable(phy); 572 kfree_skb(phy->pending_skb); 573 } 574 575 static const struct i2c_device_id st21nfca_hci_i2c_id_table[] = { 576 {ST21NFCA_HCI_DRIVER_NAME, 0}, 577 {} 578 }; 579 MODULE_DEVICE_TABLE(i2c, st21nfca_hci_i2c_id_table); 580 581 static const struct acpi_device_id st21nfca_hci_i2c_acpi_match[] __maybe_unused = { 582 {"SMO2100", 0}, 583 {} 584 }; 585 MODULE_DEVICE_TABLE(acpi, st21nfca_hci_i2c_acpi_match); 586 587 static const struct of_device_id of_st21nfca_i2c_match[] __maybe_unused = { 588 { .compatible = "st,st21nfca-i2c", }, 589 { .compatible = "st,st21nfca_i2c", }, 590 {} 591 }; 592 MODULE_DEVICE_TABLE(of, of_st21nfca_i2c_match); 593 594 static struct i2c_driver st21nfca_hci_i2c_driver = { 595 .driver = { 596 .name = ST21NFCA_HCI_I2C_DRIVER_NAME, 597 .of_match_table = of_match_ptr(of_st21nfca_i2c_match), 598 .acpi_match_table = ACPI_PTR(st21nfca_hci_i2c_acpi_match), 599 }, 600 .probe_new = st21nfca_hci_i2c_probe, 601 .id_table = st21nfca_hci_i2c_id_table, 602 .remove = st21nfca_hci_i2c_remove, 603 }; 604 module_i2c_driver(st21nfca_hci_i2c_driver); 605 606 MODULE_LICENSE("GPL"); 607 MODULE_DESCRIPTION(DRIVER_DESC); 608