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 <asm/unaligned.h> 22 23 #include <net/nfc/hci.h> 24 #include <net/nfc/llc.h> 25 #include <net/nfc/nfc.h> 26 27 #include "st21nfca.h" 28 29 /* 30 * Every frame starts with ST21NFCA_SOF_EOF and ends with ST21NFCA_SOF_EOF. 31 * Because ST21NFCA_SOF_EOF is a possible data value, there is a mecanism 32 * called byte stuffing has been introduced. 33 * 34 * if byte == ST21NFCA_SOF_EOF or ST21NFCA_ESCAPE_BYTE_STUFFING 35 * - insert ST21NFCA_ESCAPE_BYTE_STUFFING (escape byte) 36 * - xor byte with ST21NFCA_BYTE_STUFFING_MASK 37 */ 38 #define ST21NFCA_SOF_EOF 0x7e 39 #define ST21NFCA_BYTE_STUFFING_MASK 0x20 40 #define ST21NFCA_ESCAPE_BYTE_STUFFING 0x7d 41 42 /* SOF + 00 */ 43 #define ST21NFCA_FRAME_HEADROOM 2 44 45 /* 2 bytes crc + EOF */ 46 #define ST21NFCA_FRAME_TAILROOM 3 47 #define IS_START_OF_FRAME(buf) (buf[0] == ST21NFCA_SOF_EOF && \ 48 buf[1] == 0) 49 50 #define ST21NFCA_HCI_DRIVER_NAME "st21nfca_hci" 51 #define ST21NFCA_HCI_I2C_DRIVER_NAME "st21nfca_hci_i2c" 52 53 struct st21nfca_i2c_phy { 54 struct i2c_client *i2c_dev; 55 struct nfc_hci_dev *hdev; 56 57 struct gpio_desc *gpiod_ena; 58 struct st21nfca_se_status se_status; 59 60 struct sk_buff *pending_skb; 61 int current_read_len; 62 /* 63 * crc might have fail because i2c macro 64 * is disable due to other interface activity 65 */ 66 int crc_trials; 67 68 int powered; 69 int run_mode; 70 71 /* 72 * < 0 if hardware error occured (e.g. i2c err) 73 * and prevents normal operation. 74 */ 75 int hard_fault; 76 struct mutex phy_lock; 77 }; 78 79 static u8 len_seq[] = { 16, 24, 12, 29 }; 80 static u16 wait_tab[] = { 2, 3, 5, 15, 20, 40}; 81 82 #define I2C_DUMP_SKB(info, skb) \ 83 do { \ 84 pr_debug("%s:\n", info); \ 85 print_hex_dump(KERN_DEBUG, "i2c: ", DUMP_PREFIX_OFFSET, \ 86 16, 1, (skb)->data, (skb)->len, 0); \ 87 } while (0) 88 89 /* 90 * In order to get the CLF in a known state we generate an internal reboot 91 * using a proprietary command. 92 * Once the reboot is completed, we expect to receive a ST21NFCA_SOF_EOF 93 * fill buffer. 94 */ 95 static int st21nfca_hci_platform_init(struct st21nfca_i2c_phy *phy) 96 { 97 u16 wait_reboot[] = { 50, 300, 1000 }; 98 char reboot_cmd[] = { 0x7E, 0x66, 0x48, 0xF6, 0x7E }; 99 u8 tmp[ST21NFCA_HCI_LLC_MAX_SIZE]; 100 int i, r = -1; 101 102 for (i = 0; i < ARRAY_SIZE(wait_reboot) && r < 0; i++) { 103 r = i2c_master_send(phy->i2c_dev, reboot_cmd, 104 sizeof(reboot_cmd)); 105 if (r < 0) 106 msleep(wait_reboot[i]); 107 } 108 if (r < 0) 109 return r; 110 111 /* CLF is spending about 20ms to do an internal reboot */ 112 msleep(20); 113 r = -1; 114 for (i = 0; i < ARRAY_SIZE(wait_reboot) && r < 0; i++) { 115 r = i2c_master_recv(phy->i2c_dev, tmp, 116 ST21NFCA_HCI_LLC_MAX_SIZE); 117 if (r < 0) 118 msleep(wait_reboot[i]); 119 } 120 if (r < 0) 121 return r; 122 123 for (i = 0; i < ST21NFCA_HCI_LLC_MAX_SIZE && 124 tmp[i] == ST21NFCA_SOF_EOF; i++) 125 ; 126 127 if (r != ST21NFCA_HCI_LLC_MAX_SIZE) 128 return -ENODEV; 129 130 usleep_range(1000, 1500); 131 return 0; 132 } 133 134 static int st21nfca_hci_i2c_enable(void *phy_id) 135 { 136 struct st21nfca_i2c_phy *phy = phy_id; 137 138 gpiod_set_value(phy->gpiod_ena, 1); 139 phy->powered = 1; 140 phy->run_mode = ST21NFCA_HCI_MODE; 141 142 usleep_range(10000, 15000); 143 144 return 0; 145 } 146 147 static void st21nfca_hci_i2c_disable(void *phy_id) 148 { 149 struct st21nfca_i2c_phy *phy = phy_id; 150 151 gpiod_set_value(phy->gpiod_ena, 0); 152 153 phy->powered = 0; 154 } 155 156 static void st21nfca_hci_add_len_crc(struct sk_buff *skb) 157 { 158 u16 crc; 159 u8 tmp; 160 161 *(u8 *)skb_push(skb, 1) = 0; 162 163 crc = crc_ccitt(0xffff, skb->data, skb->len); 164 crc = ~crc; 165 166 tmp = crc & 0x00ff; 167 skb_put_u8(skb, tmp); 168 169 tmp = (crc >> 8) & 0x00ff; 170 skb_put_u8(skb, tmp); 171 } 172 173 static void st21nfca_hci_remove_len_crc(struct sk_buff *skb) 174 { 175 skb_pull(skb, ST21NFCA_FRAME_HEADROOM); 176 skb_trim(skb, skb->len - ST21NFCA_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 st21nfca_hci_i2c_write(void *phy_id, struct sk_buff *skb) 185 { 186 int r = -1, i, j; 187 struct st21nfca_i2c_phy *phy = phy_id; 188 struct i2c_client *client = phy->i2c_dev; 189 u8 tmp[ST21NFCA_HCI_LLC_MAX_SIZE * 2]; 190 191 I2C_DUMP_SKB("st21nfca_hci_i2c_write", skb); 192 193 if (phy->hard_fault != 0) 194 return phy->hard_fault; 195 196 /* 197 * Compute CRC before byte stuffing computation on frame 198 * Note st21nfca_hci_add_len_crc is doing a byte stuffing 199 * on its own value 200 */ 201 st21nfca_hci_add_len_crc(skb); 202 203 /* add ST21NFCA_SOF_EOF on tail */ 204 skb_put_u8(skb, ST21NFCA_SOF_EOF); 205 /* add ST21NFCA_SOF_EOF on head */ 206 *(u8 *)skb_push(skb, 1) = ST21NFCA_SOF_EOF; 207 208 /* 209 * Compute byte stuffing 210 * if byte == ST21NFCA_SOF_EOF or ST21NFCA_ESCAPE_BYTE_STUFFING 211 * insert ST21NFCA_ESCAPE_BYTE_STUFFING (escape byte) 212 * xor byte with ST21NFCA_BYTE_STUFFING_MASK 213 */ 214 tmp[0] = skb->data[0]; 215 for (i = 1, j = 1; i < skb->len - 1; i++, j++) { 216 if (skb->data[i] == ST21NFCA_SOF_EOF 217 || skb->data[i] == ST21NFCA_ESCAPE_BYTE_STUFFING) { 218 tmp[j] = ST21NFCA_ESCAPE_BYTE_STUFFING; 219 j++; 220 tmp[j] = skb->data[i] ^ ST21NFCA_BYTE_STUFFING_MASK; 221 } else { 222 tmp[j] = skb->data[i]; 223 } 224 } 225 tmp[j] = skb->data[i]; 226 j++; 227 228 /* 229 * Manage sleep mode 230 * Try 3 times to send data with delay between each 231 */ 232 mutex_lock(&phy->phy_lock); 233 for (i = 0; i < ARRAY_SIZE(wait_tab) && r < 0; i++) { 234 r = i2c_master_send(client, tmp, j); 235 if (r < 0) 236 msleep(wait_tab[i]); 237 } 238 mutex_unlock(&phy->phy_lock); 239 240 if (r >= 0) { 241 if (r != j) 242 r = -EREMOTEIO; 243 else 244 r = 0; 245 } 246 247 st21nfca_hci_remove_len_crc(skb); 248 249 return r; 250 } 251 252 static int get_frame_size(u8 *buf, int buflen) 253 { 254 int len = 0; 255 256 if (buf[len + 1] == ST21NFCA_SOF_EOF) 257 return 0; 258 259 for (len = 1; len < buflen && buf[len] != ST21NFCA_SOF_EOF; len++) 260 ; 261 262 return len; 263 } 264 265 static int check_crc(u8 *buf, int buflen) 266 { 267 u16 crc; 268 269 crc = crc_ccitt(0xffff, buf, buflen - 2); 270 crc = ~crc; 271 272 if (buf[buflen - 2] != (crc & 0xff) || buf[buflen - 1] != (crc >> 8)) { 273 pr_err(ST21NFCA_HCI_DRIVER_NAME 274 ": CRC error 0x%x != 0x%x 0x%x\n", crc, buf[buflen - 1], 275 buf[buflen - 2]); 276 277 pr_info(DRIVER_DESC ": %s : BAD CRC\n", __func__); 278 print_hex_dump(KERN_DEBUG, "crc: ", DUMP_PREFIX_NONE, 279 16, 2, buf, buflen, false); 280 return -EPERM; 281 } 282 return 0; 283 } 284 285 /* 286 * Prepare received data for upper layer. 287 * Received data include byte stuffing, crc and sof/eof 288 * which is not usable by hci part. 289 * returns: 290 * frame size without sof/eof, header and byte stuffing 291 * -EBADMSG : frame was incorrect and discarded 292 */ 293 static int st21nfca_hci_i2c_repack(struct sk_buff *skb) 294 { 295 int i, j, r, size; 296 297 if (skb->len < 1 || (skb->len > 1 && skb->data[1] != 0)) 298 return -EBADMSG; 299 300 size = get_frame_size(skb->data, skb->len); 301 if (size > 0) { 302 skb_trim(skb, size); 303 /* remove ST21NFCA byte stuffing for upper layer */ 304 for (i = 1, j = 0; i < skb->len; i++) { 305 if (skb->data[i + j] == 306 (u8) ST21NFCA_ESCAPE_BYTE_STUFFING) { 307 skb->data[i] = skb->data[i + j + 1] 308 | ST21NFCA_BYTE_STUFFING_MASK; 309 i++; 310 j++; 311 } 312 skb->data[i] = skb->data[i + j]; 313 } 314 /* remove byte stuffing useless byte */ 315 skb_trim(skb, i - j); 316 /* remove ST21NFCA_SOF_EOF from head */ 317 skb_pull(skb, 1); 318 319 r = check_crc(skb->data, skb->len); 320 if (r != 0) { 321 i = 0; 322 return -EBADMSG; 323 } 324 325 /* remove headbyte */ 326 skb_pull(skb, 1); 327 /* remove crc. Byte Stuffing is already removed here */ 328 skb_trim(skb, skb->len - 2); 329 return skb->len; 330 } 331 return 0; 332 } 333 334 /* 335 * Reads an shdlc frame and returns it in a newly allocated sk_buff. Guarantees 336 * that i2c bus will be flushed and that next read will start on a new frame. 337 * returned skb contains only LLC header and payload. 338 * returns: 339 * frame size : if received frame is complete (find ST21NFCA_SOF_EOF at 340 * end of read) 341 * -EAGAIN : if received frame is incomplete (not find ST21NFCA_SOF_EOF 342 * at end of read) 343 * -EREMOTEIO : i2c read error (fatal) 344 * -EBADMSG : frame was incorrect and discarded 345 * (value returned from st21nfca_hci_i2c_repack) 346 * -EIO : if no ST21NFCA_SOF_EOF is found after reaching 347 * the read length end sequence 348 */ 349 static int st21nfca_hci_i2c_read(struct st21nfca_i2c_phy *phy, 350 struct sk_buff *skb) 351 { 352 int r, i; 353 u8 len; 354 u8 buf[ST21NFCA_HCI_LLC_MAX_PAYLOAD]; 355 struct i2c_client *client = phy->i2c_dev; 356 357 if (phy->current_read_len < ARRAY_SIZE(len_seq)) { 358 len = len_seq[phy->current_read_len]; 359 360 /* 361 * Add retry mecanism 362 * Operation on I2C interface may fail in case of operation on 363 * RF or SWP interface 364 */ 365 r = 0; 366 mutex_lock(&phy->phy_lock); 367 for (i = 0; i < ARRAY_SIZE(wait_tab) && r <= 0; i++) { 368 r = i2c_master_recv(client, buf, len); 369 if (r < 0) 370 msleep(wait_tab[i]); 371 } 372 mutex_unlock(&phy->phy_lock); 373 374 if (r != len) { 375 phy->current_read_len = 0; 376 return -EREMOTEIO; 377 } 378 379 /* 380 * The first read sequence does not start with SOF. 381 * Data is corrupeted so we drop it. 382 */ 383 if (!phy->current_read_len && !IS_START_OF_FRAME(buf)) { 384 skb_trim(skb, 0); 385 phy->current_read_len = 0; 386 return -EIO; 387 } else if (phy->current_read_len && IS_START_OF_FRAME(buf)) { 388 /* 389 * Previous frame transmission was interrupted and 390 * the frame got repeated. 391 * Received frame start with ST21NFCA_SOF_EOF + 00. 392 */ 393 skb_trim(skb, 0); 394 phy->current_read_len = 0; 395 } 396 397 skb_put_data(skb, buf, len); 398 399 if (skb->data[skb->len - 1] == ST21NFCA_SOF_EOF) { 400 phy->current_read_len = 0; 401 return st21nfca_hci_i2c_repack(skb); 402 } 403 phy->current_read_len++; 404 return -EAGAIN; 405 } 406 return -EIO; 407 } 408 409 /* 410 * Reads an shdlc frame from the chip. This is not as straightforward as it 411 * seems. The frame format is data-crc, and corruption can occur anywhere 412 * while transiting on i2c bus, such that we could read an invalid data. 413 * The tricky case is when we read a corrupted data or crc. We must detect 414 * this here in order to determine that data can be transmitted to the hci 415 * core. This is the reason why we check the crc here. 416 * The CLF will repeat a frame until we send a RR on that frame. 417 * 418 * On ST21NFCA, IRQ goes in idle when read starts. As no size information are 419 * available in the incoming data, other IRQ might come. Every IRQ will trigger 420 * a read sequence with different length and will fill the current frame. 421 * The reception is complete once we reach a ST21NFCA_SOF_EOF. 422 */ 423 static irqreturn_t st21nfca_hci_irq_thread_fn(int irq, void *phy_id) 424 { 425 struct st21nfca_i2c_phy *phy = phy_id; 426 struct i2c_client *client; 427 428 int r; 429 430 if (!phy || irq != phy->i2c_dev->irq) { 431 WARN_ON_ONCE(1); 432 return IRQ_NONE; 433 } 434 435 client = phy->i2c_dev; 436 dev_dbg(&client->dev, "IRQ\n"); 437 438 if (phy->hard_fault != 0) 439 return IRQ_HANDLED; 440 441 r = st21nfca_hci_i2c_read(phy, phy->pending_skb); 442 if (r == -EREMOTEIO) { 443 phy->hard_fault = r; 444 445 nfc_hci_recv_frame(phy->hdev, NULL); 446 447 return IRQ_HANDLED; 448 } else if (r == -EAGAIN || r == -EIO) { 449 return IRQ_HANDLED; 450 } else if (r == -EBADMSG && phy->crc_trials < ARRAY_SIZE(wait_tab)) { 451 /* 452 * With ST21NFCA, only one interface (I2C, RF or SWP) 453 * may be active at a time. 454 * Having incorrect crc is usually due to i2c macrocell 455 * deactivation in the middle of a transmission. 456 * It may generate corrupted data on i2c. 457 * We give sometime to get i2c back. 458 * The complete frame will be repeated. 459 */ 460 msleep(wait_tab[phy->crc_trials]); 461 phy->crc_trials++; 462 phy->current_read_len = 0; 463 kfree_skb(phy->pending_skb); 464 } else if (r > 0) { 465 /* 466 * We succeeded to read data from the CLF and 467 * data is valid. 468 * Reset counter. 469 */ 470 nfc_hci_recv_frame(phy->hdev, phy->pending_skb); 471 phy->crc_trials = 0; 472 } else { 473 kfree_skb(phy->pending_skb); 474 } 475 476 phy->pending_skb = alloc_skb(ST21NFCA_HCI_LLC_MAX_SIZE * 2, GFP_KERNEL); 477 if (phy->pending_skb == NULL) { 478 phy->hard_fault = -ENOMEM; 479 nfc_hci_recv_frame(phy->hdev, NULL); 480 } 481 482 return IRQ_HANDLED; 483 } 484 485 static struct nfc_phy_ops i2c_phy_ops = { 486 .write = st21nfca_hci_i2c_write, 487 .enable = st21nfca_hci_i2c_enable, 488 .disable = st21nfca_hci_i2c_disable, 489 }; 490 491 static const struct acpi_gpio_params enable_gpios = { 1, 0, false }; 492 493 static const struct acpi_gpio_mapping acpi_st21nfca_gpios[] = { 494 { "enable-gpios", &enable_gpios, 1 }, 495 {}, 496 }; 497 498 static int st21nfca_hci_i2c_probe(struct i2c_client *client, 499 const struct i2c_device_id *id) 500 { 501 struct device *dev = &client->dev; 502 struct st21nfca_i2c_phy *phy; 503 int r; 504 505 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) { 506 nfc_err(&client->dev, "Need I2C_FUNC_I2C\n"); 507 return -ENODEV; 508 } 509 510 phy = devm_kzalloc(&client->dev, sizeof(struct st21nfca_i2c_phy), 511 GFP_KERNEL); 512 if (!phy) 513 return -ENOMEM; 514 515 phy->i2c_dev = client; 516 phy->pending_skb = alloc_skb(ST21NFCA_HCI_LLC_MAX_SIZE * 2, GFP_KERNEL); 517 if (phy->pending_skb == NULL) 518 return -ENOMEM; 519 520 phy->current_read_len = 0; 521 phy->crc_trials = 0; 522 mutex_init(&phy->phy_lock); 523 i2c_set_clientdata(client, phy); 524 525 r = devm_acpi_dev_add_driver_gpios(dev, acpi_st21nfca_gpios); 526 if (r) 527 dev_dbg(dev, "Unable to add GPIO mapping table\n"); 528 529 /* Get EN GPIO from resource provider */ 530 phy->gpiod_ena = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW); 531 if (IS_ERR(phy->gpiod_ena)) { 532 nfc_err(dev, "Unable to get ENABLE GPIO\n"); 533 return PTR_ERR(phy->gpiod_ena); 534 } 535 536 phy->se_status.is_ese_present = 537 device_property_read_bool(&client->dev, "ese-present"); 538 phy->se_status.is_uicc_present = 539 device_property_read_bool(&client->dev, "uicc-present"); 540 541 r = st21nfca_hci_platform_init(phy); 542 if (r < 0) { 543 nfc_err(&client->dev, "Unable to reboot st21nfca\n"); 544 return r; 545 } 546 547 r = devm_request_threaded_irq(&client->dev, client->irq, NULL, 548 st21nfca_hci_irq_thread_fn, 549 IRQF_ONESHOT, 550 ST21NFCA_HCI_DRIVER_NAME, phy); 551 if (r < 0) { 552 nfc_err(&client->dev, "Unable to register IRQ handler\n"); 553 return r; 554 } 555 556 return st21nfca_hci_probe(phy, &i2c_phy_ops, LLC_SHDLC_NAME, 557 ST21NFCA_FRAME_HEADROOM, 558 ST21NFCA_FRAME_TAILROOM, 559 ST21NFCA_HCI_LLC_MAX_PAYLOAD, 560 &phy->hdev, 561 &phy->se_status); 562 } 563 564 static int 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); 572 573 return 0; 574 } 575 576 static const struct i2c_device_id st21nfca_hci_i2c_id_table[] = { 577 {ST21NFCA_HCI_DRIVER_NAME, 0}, 578 {} 579 }; 580 MODULE_DEVICE_TABLE(i2c, st21nfca_hci_i2c_id_table); 581 582 static const struct acpi_device_id st21nfca_hci_i2c_acpi_match[] __maybe_unused = { 583 {"SMO2100", 0}, 584 {} 585 }; 586 MODULE_DEVICE_TABLE(acpi, st21nfca_hci_i2c_acpi_match); 587 588 static const struct of_device_id of_st21nfca_i2c_match[] __maybe_unused = { 589 { .compatible = "st,st21nfca-i2c", }, 590 { .compatible = "st,st21nfca_i2c", }, 591 {} 592 }; 593 MODULE_DEVICE_TABLE(of, of_st21nfca_i2c_match); 594 595 static struct i2c_driver st21nfca_hci_i2c_driver = { 596 .driver = { 597 .name = ST21NFCA_HCI_I2C_DRIVER_NAME, 598 .of_match_table = of_match_ptr(of_st21nfca_i2c_match), 599 .acpi_match_table = ACPI_PTR(st21nfca_hci_i2c_acpi_match), 600 }, 601 .probe = st21nfca_hci_i2c_probe, 602 .id_table = st21nfca_hci_i2c_id_table, 603 .remove = st21nfca_hci_i2c_remove, 604 }; 605 module_i2c_driver(st21nfca_hci_i2c_driver); 606 607 MODULE_LICENSE("GPL"); 608 MODULE_DESCRIPTION(DRIVER_DESC); 609