1 /* 2 * A FSI master controller, using a simple GPIO bit-banging interface 3 */ 4 5 #include <linux/crc4.h> 6 #include <linux/delay.h> 7 #include <linux/device.h> 8 #include <linux/fsi.h> 9 #include <linux/gpio/consumer.h> 10 #include <linux/io.h> 11 #include <linux/irqflags.h> 12 #include <linux/module.h> 13 #include <linux/of.h> 14 #include <linux/platform_device.h> 15 #include <linux/slab.h> 16 17 #include "fsi-master.h" 18 19 #define FSI_GPIO_STD_DLY 1 /* Standard pin delay in nS */ 20 #define LAST_ADDR_INVALID 0x1 21 22 struct fsi_master_gpio { 23 struct fsi_master master; 24 struct device *dev; 25 struct mutex cmd_lock; /* mutex for command ordering */ 26 struct gpio_desc *gpio_clk; 27 struct gpio_desc *gpio_data; 28 struct gpio_desc *gpio_trans; /* Voltage translator */ 29 struct gpio_desc *gpio_enable; /* FSI enable */ 30 struct gpio_desc *gpio_mux; /* Mux control */ 31 bool external_mode; 32 bool no_delays; 33 uint32_t last_addr; 34 uint8_t t_send_delay; 35 uint8_t t_echo_delay; 36 }; 37 38 #define CREATE_TRACE_POINTS 39 #include <trace/events/fsi_master_gpio.h> 40 41 #define to_fsi_master_gpio(m) container_of(m, struct fsi_master_gpio, master) 42 43 struct fsi_gpio_msg { 44 uint64_t msg; 45 uint8_t bits; 46 }; 47 48 static void clock_toggle(struct fsi_master_gpio *master, int count) 49 { 50 int i; 51 52 for (i = 0; i < count; i++) { 53 if (!master->no_delays) 54 ndelay(FSI_GPIO_STD_DLY); 55 gpiod_set_value(master->gpio_clk, 0); 56 if (!master->no_delays) 57 ndelay(FSI_GPIO_STD_DLY); 58 gpiod_set_value(master->gpio_clk, 1); 59 } 60 } 61 62 static int sda_clock_in(struct fsi_master_gpio *master) 63 { 64 int in; 65 66 if (!master->no_delays) 67 ndelay(FSI_GPIO_STD_DLY); 68 gpiod_set_value(master->gpio_clk, 0); 69 70 /* Dummy read to feed the synchronizers */ 71 gpiod_get_value(master->gpio_data); 72 73 /* Actual data read */ 74 in = gpiod_get_value(master->gpio_data); 75 if (!master->no_delays) 76 ndelay(FSI_GPIO_STD_DLY); 77 gpiod_set_value(master->gpio_clk, 1); 78 return in ? 1 : 0; 79 } 80 81 static void sda_out(struct fsi_master_gpio *master, int value) 82 { 83 gpiod_set_value(master->gpio_data, value); 84 } 85 86 static void set_sda_input(struct fsi_master_gpio *master) 87 { 88 gpiod_direction_input(master->gpio_data); 89 gpiod_set_value(master->gpio_trans, 0); 90 } 91 92 static void set_sda_output(struct fsi_master_gpio *master, int value) 93 { 94 gpiod_set_value(master->gpio_trans, 1); 95 gpiod_direction_output(master->gpio_data, value); 96 } 97 98 static void clock_zeros(struct fsi_master_gpio *master, int count) 99 { 100 trace_fsi_master_gpio_clock_zeros(master, count); 101 set_sda_output(master, 1); 102 clock_toggle(master, count); 103 } 104 105 static void echo_delay(struct fsi_master_gpio *master) 106 { 107 clock_zeros(master, master->t_echo_delay); 108 } 109 110 111 static void serial_in(struct fsi_master_gpio *master, struct fsi_gpio_msg *msg, 112 uint8_t num_bits) 113 { 114 uint8_t bit, in_bit; 115 116 set_sda_input(master); 117 118 for (bit = 0; bit < num_bits; bit++) { 119 in_bit = sda_clock_in(master); 120 msg->msg <<= 1; 121 msg->msg |= ~in_bit & 0x1; /* Data is active low */ 122 } 123 msg->bits += num_bits; 124 125 trace_fsi_master_gpio_in(master, num_bits, msg->msg); 126 } 127 128 static void serial_out(struct fsi_master_gpio *master, 129 const struct fsi_gpio_msg *cmd) 130 { 131 uint8_t bit; 132 uint64_t msg = ~cmd->msg; /* Data is active low */ 133 uint64_t sda_mask = 0x1ULL << (cmd->bits - 1); 134 uint64_t last_bit = ~0; 135 int next_bit; 136 137 trace_fsi_master_gpio_out(master, cmd->bits, cmd->msg); 138 139 if (!cmd->bits) { 140 dev_warn(master->dev, "trying to output 0 bits\n"); 141 return; 142 } 143 set_sda_output(master, 0); 144 145 /* Send the start bit */ 146 sda_out(master, 0); 147 clock_toggle(master, 1); 148 149 /* Send the message */ 150 for (bit = 0; bit < cmd->bits; bit++) { 151 next_bit = (msg & sda_mask) >> (cmd->bits - 1); 152 if (last_bit ^ next_bit) { 153 sda_out(master, next_bit); 154 last_bit = next_bit; 155 } 156 clock_toggle(master, 1); 157 msg <<= 1; 158 } 159 } 160 161 static void msg_push_bits(struct fsi_gpio_msg *msg, uint64_t data, int bits) 162 { 163 msg->msg <<= bits; 164 msg->msg |= data & ((1ull << bits) - 1); 165 msg->bits += bits; 166 } 167 168 static void msg_push_crc(struct fsi_gpio_msg *msg) 169 { 170 uint8_t crc; 171 int top; 172 173 top = msg->bits & 0x3; 174 175 /* start bit, and any non-aligned top bits */ 176 crc = crc4(0, 1 << top | msg->msg >> (msg->bits - top), top + 1); 177 178 /* aligned bits */ 179 crc = crc4(crc, msg->msg, msg->bits - top); 180 181 msg_push_bits(msg, crc, 4); 182 } 183 184 static bool check_same_address(struct fsi_master_gpio *master, int id, 185 uint32_t addr) 186 { 187 /* this will also handle LAST_ADDR_INVALID */ 188 return master->last_addr == (((id & 0x3) << 21) | (addr & ~0x3)); 189 } 190 191 static bool check_relative_address(struct fsi_master_gpio *master, int id, 192 uint32_t addr, uint32_t *rel_addrp) 193 { 194 uint32_t last_addr = master->last_addr; 195 int32_t rel_addr; 196 197 if (last_addr == LAST_ADDR_INVALID) 198 return false; 199 200 /* We may be in 23-bit addressing mode, which uses the id as the 201 * top two address bits. So, if we're referencing a different ID, 202 * use absolute addresses. 203 */ 204 if (((last_addr >> 21) & 0x3) != id) 205 return false; 206 207 /* remove the top two bits from any 23-bit addressing */ 208 last_addr &= (1 << 21) - 1; 209 210 /* We know that the addresses are limited to 21 bits, so this won't 211 * overflow the signed rel_addr */ 212 rel_addr = addr - last_addr; 213 if (rel_addr > 255 || rel_addr < -256) 214 return false; 215 216 *rel_addrp = (uint32_t)rel_addr; 217 218 return true; 219 } 220 221 static void last_address_update(struct fsi_master_gpio *master, 222 int id, bool valid, uint32_t addr) 223 { 224 if (!valid) 225 master->last_addr = LAST_ADDR_INVALID; 226 else 227 master->last_addr = ((id & 0x3) << 21) | (addr & ~0x3); 228 } 229 230 /* 231 * Encode an Absolute/Relative/Same Address command 232 */ 233 static void build_ar_command(struct fsi_master_gpio *master, 234 struct fsi_gpio_msg *cmd, uint8_t id, 235 uint32_t addr, size_t size, const void *data) 236 { 237 int i, addr_bits, opcode_bits; 238 bool write = !!data; 239 uint8_t ds, opcode; 240 uint32_t rel_addr; 241 242 cmd->bits = 0; 243 cmd->msg = 0; 244 245 /* we have 21 bits of address max */ 246 addr &= ((1 << 21) - 1); 247 248 /* cmd opcodes are variable length - SAME_AR is only two bits */ 249 opcode_bits = 3; 250 251 if (check_same_address(master, id, addr)) { 252 /* we still address the byte offset within the word */ 253 addr_bits = 2; 254 opcode_bits = 2; 255 opcode = FSI_CMD_SAME_AR; 256 trace_fsi_master_gpio_cmd_same_addr(master); 257 258 } else if (check_relative_address(master, id, addr, &rel_addr)) { 259 /* 8 bits plus sign */ 260 addr_bits = 9; 261 addr = rel_addr; 262 opcode = FSI_CMD_REL_AR; 263 trace_fsi_master_gpio_cmd_rel_addr(master, rel_addr); 264 265 } else { 266 addr_bits = 21; 267 opcode = FSI_CMD_ABS_AR; 268 trace_fsi_master_gpio_cmd_abs_addr(master, addr); 269 } 270 271 /* 272 * The read/write size is encoded in the lower bits of the address 273 * (as it must be naturally-aligned), and the following ds bit. 274 * 275 * size addr:1 addr:0 ds 276 * 1 x x 0 277 * 2 x 0 1 278 * 4 0 1 1 279 * 280 */ 281 ds = size > 1 ? 1 : 0; 282 addr &= ~(size - 1); 283 if (size == 4) 284 addr |= 1; 285 286 msg_push_bits(cmd, id, 2); 287 msg_push_bits(cmd, opcode, opcode_bits); 288 msg_push_bits(cmd, write ? 0 : 1, 1); 289 msg_push_bits(cmd, addr, addr_bits); 290 msg_push_bits(cmd, ds, 1); 291 for (i = 0; write && i < size; i++) 292 msg_push_bits(cmd, ((uint8_t *)data)[i], 8); 293 294 msg_push_crc(cmd); 295 } 296 297 static void build_dpoll_command(struct fsi_gpio_msg *cmd, uint8_t slave_id) 298 { 299 cmd->bits = 0; 300 cmd->msg = 0; 301 302 msg_push_bits(cmd, slave_id, 2); 303 msg_push_bits(cmd, FSI_CMD_DPOLL, 3); 304 msg_push_crc(cmd); 305 } 306 307 static void build_epoll_command(struct fsi_gpio_msg *cmd, uint8_t slave_id) 308 { 309 cmd->bits = 0; 310 cmd->msg = 0; 311 312 msg_push_bits(cmd, slave_id, 2); 313 msg_push_bits(cmd, FSI_CMD_EPOLL, 3); 314 msg_push_crc(cmd); 315 } 316 317 static void build_term_command(struct fsi_gpio_msg *cmd, uint8_t slave_id) 318 { 319 cmd->bits = 0; 320 cmd->msg = 0; 321 322 msg_push_bits(cmd, slave_id, 2); 323 msg_push_bits(cmd, FSI_CMD_TERM, 6); 324 msg_push_crc(cmd); 325 } 326 327 /* 328 * Note: callers rely specifically on this returning -EAGAIN for 329 * a CRC error detected in the response. Use other error code 330 * for other situations. It will be converted to something else 331 * higher up the stack before it reaches userspace. 332 */ 333 static int read_one_response(struct fsi_master_gpio *master, 334 uint8_t data_size, struct fsi_gpio_msg *msgp, uint8_t *tagp) 335 { 336 struct fsi_gpio_msg msg; 337 unsigned long flags; 338 uint32_t crc; 339 uint8_t tag; 340 int i; 341 342 local_irq_save(flags); 343 344 /* wait for the start bit */ 345 for (i = 0; i < FSI_MASTER_MTOE_COUNT; i++) { 346 msg.bits = 0; 347 msg.msg = 0; 348 serial_in(master, &msg, 1); 349 if (msg.msg) 350 break; 351 } 352 if (i == FSI_MASTER_MTOE_COUNT) { 353 dev_dbg(master->dev, 354 "Master time out waiting for response\n"); 355 local_irq_restore(flags); 356 return -ETIMEDOUT; 357 } 358 359 msg.bits = 0; 360 msg.msg = 0; 361 362 /* Read slave ID & response tag */ 363 serial_in(master, &msg, 4); 364 365 tag = msg.msg & 0x3; 366 367 /* If we have an ACK and we're expecting data, clock the data in too */ 368 if (tag == FSI_RESP_ACK && data_size) 369 serial_in(master, &msg, data_size * 8); 370 371 /* read CRC */ 372 serial_in(master, &msg, FSI_CRC_SIZE); 373 374 local_irq_restore(flags); 375 376 /* we have a whole message now; check CRC */ 377 crc = crc4(0, 1, 1); 378 crc = crc4(crc, msg.msg, msg.bits); 379 if (crc) { 380 /* Check if it's all 1's, that probably means the host is off */ 381 if (((~msg.msg) & ((1ull << msg.bits) - 1)) == 0) 382 return -ENODEV; 383 dev_dbg(master->dev, "ERR response CRC msg: 0x%016llx (%d bits)\n", 384 msg.msg, msg.bits); 385 return -EAGAIN; 386 } 387 388 if (msgp) 389 *msgp = msg; 390 if (tagp) 391 *tagp = tag; 392 393 return 0; 394 } 395 396 static int issue_term(struct fsi_master_gpio *master, uint8_t slave) 397 { 398 struct fsi_gpio_msg cmd; 399 unsigned long flags; 400 uint8_t tag; 401 int rc; 402 403 build_term_command(&cmd, slave); 404 405 local_irq_save(flags); 406 serial_out(master, &cmd); 407 echo_delay(master); 408 local_irq_restore(flags); 409 410 rc = read_one_response(master, 0, NULL, &tag); 411 if (rc < 0) { 412 dev_err(master->dev, 413 "TERM failed; lost communication with slave\n"); 414 return -EIO; 415 } else if (tag != FSI_RESP_ACK) { 416 dev_err(master->dev, "TERM failed; response %d\n", tag); 417 return -EIO; 418 } 419 420 return 0; 421 } 422 423 static int poll_for_response(struct fsi_master_gpio *master, 424 uint8_t slave, uint8_t size, void *data) 425 { 426 struct fsi_gpio_msg response, cmd; 427 int busy_count = 0, rc, i; 428 unsigned long flags; 429 uint8_t tag; 430 uint8_t *data_byte = data; 431 int crc_err_retries = 0; 432 retry: 433 rc = read_one_response(master, size, &response, &tag); 434 435 /* Handle retries on CRC errors */ 436 if (rc == -EAGAIN) { 437 /* Too many retries ? */ 438 if (crc_err_retries++ > FSI_CRC_ERR_RETRIES) { 439 /* 440 * Pass it up as a -EIO otherwise upper level will retry 441 * the whole command which isn't what we want here. 442 */ 443 rc = -EIO; 444 goto fail; 445 } 446 dev_dbg(master->dev, 447 "CRC error retry %d\n", crc_err_retries); 448 trace_fsi_master_gpio_crc_rsp_error(master); 449 build_epoll_command(&cmd, slave); 450 local_irq_save(flags); 451 clock_zeros(master, FSI_MASTER_EPOLL_CLOCKS); 452 serial_out(master, &cmd); 453 echo_delay(master); 454 local_irq_restore(flags); 455 goto retry; 456 } else if (rc) 457 goto fail; 458 459 switch (tag) { 460 case FSI_RESP_ACK: 461 if (size && data) { 462 uint64_t val = response.msg; 463 /* clear crc & mask */ 464 val >>= 4; 465 val &= (1ull << (size * 8)) - 1; 466 467 for (i = 0; i < size; i++) { 468 data_byte[size-i-1] = val; 469 val >>= 8; 470 } 471 } 472 break; 473 case FSI_RESP_BUSY: 474 /* 475 * Its necessary to clock slave before issuing 476 * d-poll, not indicated in the hardware protocol 477 * spec. < 20 clocks causes slave to hang, 21 ok. 478 */ 479 if (busy_count++ < FSI_MASTER_MAX_BUSY) { 480 build_dpoll_command(&cmd, slave); 481 local_irq_save(flags); 482 clock_zeros(master, FSI_MASTER_DPOLL_CLOCKS); 483 serial_out(master, &cmd); 484 echo_delay(master); 485 local_irq_restore(flags); 486 goto retry; 487 } 488 dev_warn(master->dev, 489 "ERR slave is stuck in busy state, issuing TERM\n"); 490 local_irq_save(flags); 491 clock_zeros(master, FSI_MASTER_DPOLL_CLOCKS); 492 local_irq_restore(flags); 493 issue_term(master, slave); 494 rc = -EIO; 495 break; 496 497 case FSI_RESP_ERRA: 498 dev_dbg(master->dev, "ERRA received: 0x%x\n", (int)response.msg); 499 rc = -EIO; 500 break; 501 case FSI_RESP_ERRC: 502 dev_dbg(master->dev, "ERRC received: 0x%x\n", (int)response.msg); 503 trace_fsi_master_gpio_crc_cmd_error(master); 504 rc = -EAGAIN; 505 break; 506 } 507 508 if (busy_count > 0) 509 trace_fsi_master_gpio_poll_response_busy(master, busy_count); 510 fail: 511 /* 512 * tSendDelay clocks, avoids signal reflections when switching 513 * from receive of response back to send of data. 514 */ 515 local_irq_save(flags); 516 clock_zeros(master, master->t_send_delay); 517 local_irq_restore(flags); 518 519 return rc; 520 } 521 522 static int send_request(struct fsi_master_gpio *master, 523 struct fsi_gpio_msg *cmd) 524 { 525 unsigned long flags; 526 527 if (master->external_mode) 528 return -EBUSY; 529 530 local_irq_save(flags); 531 serial_out(master, cmd); 532 echo_delay(master); 533 local_irq_restore(flags); 534 535 return 0; 536 } 537 538 static int fsi_master_gpio_xfer(struct fsi_master_gpio *master, uint8_t slave, 539 struct fsi_gpio_msg *cmd, size_t resp_len, void *resp) 540 { 541 int rc = -EAGAIN, retries = 0; 542 543 while ((retries++) < FSI_CRC_ERR_RETRIES) { 544 rc = send_request(master, cmd); 545 if (rc) 546 break; 547 rc = poll_for_response(master, slave, resp_len, resp); 548 if (rc != -EAGAIN) 549 break; 550 rc = -EIO; 551 dev_warn(master->dev, "ECRC retry %d\n", retries); 552 553 /* Pace it a bit before retry */ 554 msleep(1); 555 } 556 557 return rc; 558 } 559 560 static int fsi_master_gpio_read(struct fsi_master *_master, int link, 561 uint8_t id, uint32_t addr, void *val, size_t size) 562 { 563 struct fsi_master_gpio *master = to_fsi_master_gpio(_master); 564 struct fsi_gpio_msg cmd; 565 int rc; 566 567 if (link != 0) 568 return -ENODEV; 569 570 mutex_lock(&master->cmd_lock); 571 build_ar_command(master, &cmd, id, addr, size, NULL); 572 rc = fsi_master_gpio_xfer(master, id, &cmd, size, val); 573 last_address_update(master, id, rc == 0, addr); 574 mutex_unlock(&master->cmd_lock); 575 576 return rc; 577 } 578 579 static int fsi_master_gpio_write(struct fsi_master *_master, int link, 580 uint8_t id, uint32_t addr, const void *val, size_t size) 581 { 582 struct fsi_master_gpio *master = to_fsi_master_gpio(_master); 583 struct fsi_gpio_msg cmd; 584 int rc; 585 586 if (link != 0) 587 return -ENODEV; 588 589 mutex_lock(&master->cmd_lock); 590 build_ar_command(master, &cmd, id, addr, size, val); 591 rc = fsi_master_gpio_xfer(master, id, &cmd, 0, NULL); 592 last_address_update(master, id, rc == 0, addr); 593 mutex_unlock(&master->cmd_lock); 594 595 return rc; 596 } 597 598 static int fsi_master_gpio_term(struct fsi_master *_master, 599 int link, uint8_t id) 600 { 601 struct fsi_master_gpio *master = to_fsi_master_gpio(_master); 602 struct fsi_gpio_msg cmd; 603 int rc; 604 605 if (link != 0) 606 return -ENODEV; 607 608 mutex_lock(&master->cmd_lock); 609 build_term_command(&cmd, id); 610 rc = fsi_master_gpio_xfer(master, id, &cmd, 0, NULL); 611 last_address_update(master, id, false, 0); 612 mutex_unlock(&master->cmd_lock); 613 614 return rc; 615 } 616 617 static int fsi_master_gpio_break(struct fsi_master *_master, int link) 618 { 619 struct fsi_master_gpio *master = to_fsi_master_gpio(_master); 620 unsigned long flags; 621 622 if (link != 0) 623 return -ENODEV; 624 625 trace_fsi_master_gpio_break(master); 626 627 mutex_lock(&master->cmd_lock); 628 if (master->external_mode) { 629 mutex_unlock(&master->cmd_lock); 630 return -EBUSY; 631 } 632 633 local_irq_save(flags); 634 635 set_sda_output(master, 1); 636 sda_out(master, 1); 637 clock_toggle(master, FSI_PRE_BREAK_CLOCKS); 638 sda_out(master, 0); 639 clock_toggle(master, FSI_BREAK_CLOCKS); 640 echo_delay(master); 641 sda_out(master, 1); 642 clock_toggle(master, FSI_POST_BREAK_CLOCKS); 643 644 local_irq_restore(flags); 645 646 last_address_update(master, 0, false, 0); 647 mutex_unlock(&master->cmd_lock); 648 649 /* Wait for logic reset to take effect */ 650 udelay(200); 651 652 return 0; 653 } 654 655 static void fsi_master_gpio_init(struct fsi_master_gpio *master) 656 { 657 unsigned long flags; 658 659 gpiod_direction_output(master->gpio_mux, 1); 660 gpiod_direction_output(master->gpio_trans, 1); 661 gpiod_direction_output(master->gpio_enable, 1); 662 gpiod_direction_output(master->gpio_clk, 1); 663 gpiod_direction_output(master->gpio_data, 1); 664 665 /* todo: evaluate if clocks can be reduced */ 666 local_irq_save(flags); 667 clock_zeros(master, FSI_INIT_CLOCKS); 668 local_irq_restore(flags); 669 } 670 671 static void fsi_master_gpio_init_external(struct fsi_master_gpio *master) 672 { 673 gpiod_direction_output(master->gpio_mux, 0); 674 gpiod_direction_output(master->gpio_trans, 0); 675 gpiod_direction_output(master->gpio_enable, 1); 676 gpiod_direction_input(master->gpio_clk); 677 gpiod_direction_input(master->gpio_data); 678 } 679 680 static int fsi_master_gpio_link_enable(struct fsi_master *_master, int link) 681 { 682 struct fsi_master_gpio *master = to_fsi_master_gpio(_master); 683 int rc = -EBUSY; 684 685 if (link != 0) 686 return -ENODEV; 687 688 mutex_lock(&master->cmd_lock); 689 if (!master->external_mode) { 690 gpiod_set_value(master->gpio_enable, 1); 691 rc = 0; 692 } 693 mutex_unlock(&master->cmd_lock); 694 695 return rc; 696 } 697 698 static int fsi_master_gpio_link_config(struct fsi_master *_master, int link, 699 u8 t_send_delay, u8 t_echo_delay) 700 { 701 struct fsi_master_gpio *master = to_fsi_master_gpio(_master); 702 703 if (link != 0) 704 return -ENODEV; 705 706 mutex_lock(&master->cmd_lock); 707 master->t_send_delay = t_send_delay; 708 master->t_echo_delay = t_echo_delay; 709 mutex_unlock(&master->cmd_lock); 710 711 return 0; 712 } 713 714 static ssize_t external_mode_show(struct device *dev, 715 struct device_attribute *attr, char *buf) 716 { 717 struct fsi_master_gpio *master = dev_get_drvdata(dev); 718 719 return snprintf(buf, PAGE_SIZE - 1, "%u\n", 720 master->external_mode ? 1 : 0); 721 } 722 723 static ssize_t external_mode_store(struct device *dev, 724 struct device_attribute *attr, const char *buf, size_t count) 725 { 726 struct fsi_master_gpio *master = dev_get_drvdata(dev); 727 unsigned long val; 728 bool external_mode; 729 int err; 730 731 err = kstrtoul(buf, 0, &val); 732 if (err) 733 return err; 734 735 external_mode = !!val; 736 737 mutex_lock(&master->cmd_lock); 738 739 if (external_mode == master->external_mode) { 740 mutex_unlock(&master->cmd_lock); 741 return count; 742 } 743 744 master->external_mode = external_mode; 745 if (master->external_mode) 746 fsi_master_gpio_init_external(master); 747 else 748 fsi_master_gpio_init(master); 749 750 mutex_unlock(&master->cmd_lock); 751 752 fsi_master_rescan(&master->master); 753 754 return count; 755 } 756 757 static DEVICE_ATTR(external_mode, 0664, 758 external_mode_show, external_mode_store); 759 760 static void fsi_master_gpio_release(struct device *dev) 761 { 762 struct fsi_master_gpio *master = to_fsi_master_gpio(dev_to_fsi_master(dev)); 763 764 of_node_put(dev_of_node(master->dev)); 765 766 kfree(master); 767 } 768 769 static int fsi_master_gpio_probe(struct platform_device *pdev) 770 { 771 struct fsi_master_gpio *master; 772 struct gpio_desc *gpio; 773 int rc; 774 775 master = kzalloc(sizeof(*master), GFP_KERNEL); 776 if (!master) 777 return -ENOMEM; 778 779 master->dev = &pdev->dev; 780 master->master.dev.parent = master->dev; 781 master->master.dev.of_node = of_node_get(dev_of_node(master->dev)); 782 master->master.dev.release = fsi_master_gpio_release; 783 master->last_addr = LAST_ADDR_INVALID; 784 785 gpio = devm_gpiod_get(&pdev->dev, "clock", 0); 786 if (IS_ERR(gpio)) { 787 dev_err(&pdev->dev, "failed to get clock gpio\n"); 788 rc = PTR_ERR(gpio); 789 goto err_free; 790 } 791 master->gpio_clk = gpio; 792 793 gpio = devm_gpiod_get(&pdev->dev, "data", 0); 794 if (IS_ERR(gpio)) { 795 dev_err(&pdev->dev, "failed to get data gpio\n"); 796 rc = PTR_ERR(gpio); 797 goto err_free; 798 } 799 master->gpio_data = gpio; 800 801 /* Optional GPIOs */ 802 gpio = devm_gpiod_get_optional(&pdev->dev, "trans", 0); 803 if (IS_ERR(gpio)) { 804 dev_err(&pdev->dev, "failed to get trans gpio\n"); 805 rc = PTR_ERR(gpio); 806 goto err_free; 807 } 808 master->gpio_trans = gpio; 809 810 gpio = devm_gpiod_get_optional(&pdev->dev, "enable", 0); 811 if (IS_ERR(gpio)) { 812 dev_err(&pdev->dev, "failed to get enable gpio\n"); 813 rc = PTR_ERR(gpio); 814 goto err_free; 815 } 816 master->gpio_enable = gpio; 817 818 gpio = devm_gpiod_get_optional(&pdev->dev, "mux", 0); 819 if (IS_ERR(gpio)) { 820 dev_err(&pdev->dev, "failed to get mux gpio\n"); 821 rc = PTR_ERR(gpio); 822 goto err_free; 823 } 824 master->gpio_mux = gpio; 825 826 /* 827 * Check if GPIO block is slow enought that no extra delays 828 * are necessary. This improves performance on ast2500 by 829 * an order of magnitude. 830 */ 831 master->no_delays = device_property_present(&pdev->dev, "no-gpio-delays"); 832 833 /* Default FSI command delays */ 834 master->t_send_delay = FSI_SEND_DELAY_CLOCKS; 835 master->t_echo_delay = FSI_ECHO_DELAY_CLOCKS; 836 837 master->master.n_links = 1; 838 master->master.flags = FSI_MASTER_FLAG_SWCLOCK; 839 master->master.read = fsi_master_gpio_read; 840 master->master.write = fsi_master_gpio_write; 841 master->master.term = fsi_master_gpio_term; 842 master->master.send_break = fsi_master_gpio_break; 843 master->master.link_enable = fsi_master_gpio_link_enable; 844 master->master.link_config = fsi_master_gpio_link_config; 845 platform_set_drvdata(pdev, master); 846 mutex_init(&master->cmd_lock); 847 848 fsi_master_gpio_init(master); 849 850 rc = device_create_file(&pdev->dev, &dev_attr_external_mode); 851 if (rc) 852 goto err_free; 853 854 rc = fsi_master_register(&master->master); 855 if (rc) { 856 device_remove_file(&pdev->dev, &dev_attr_external_mode); 857 put_device(&master->master.dev); 858 return rc; 859 } 860 return 0; 861 err_free: 862 kfree(master); 863 return rc; 864 } 865 866 867 868 static int fsi_master_gpio_remove(struct platform_device *pdev) 869 { 870 struct fsi_master_gpio *master = platform_get_drvdata(pdev); 871 872 device_remove_file(&pdev->dev, &dev_attr_external_mode); 873 874 fsi_master_unregister(&master->master); 875 876 return 0; 877 } 878 879 static const struct of_device_id fsi_master_gpio_match[] = { 880 { .compatible = "fsi-master-gpio" }, 881 { }, 882 }; 883 884 static struct platform_driver fsi_master_gpio_driver = { 885 .driver = { 886 .name = "fsi-master-gpio", 887 .of_match_table = fsi_master_gpio_match, 888 }, 889 .probe = fsi_master_gpio_probe, 890 .remove = fsi_master_gpio_remove, 891 }; 892 893 module_platform_driver(fsi_master_gpio_driver); 894 MODULE_LICENSE("GPL"); 895