drivers/fsi/fsi-master-gpio.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * A FSI master controller, using a simple GPIO bit-banging interface
   4  */
   5
   6 #include <linux/crc4.h>
   7 #include <linux/delay.h>
   8 #include <linux/device.h>
   9 #include <linux/fsi.h>
  10 #include <linux/gpio/consumer.h>
  11 #include <linux/io.h>
  12 #include <linux/irqflags.h>
  13 #include <linux/module.h>
  14 #include <linux/of.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/slab.h>
  17
  18 #include "fsi-master.h"
  19
  20 #define FSI_GPIO_STD_DLY        1       /* Standard pin delay in nS */
  21 #define LAST_ADDR_INVALID               0x1
  22
  23 struct fsi_master_gpio {
  24         struct fsi_master       master;
  25         struct device           *dev;
  26         struct mutex            cmd_lock;       /* mutex for command ordering */
  27         struct gpio_desc        *gpio_clk;
  28         struct gpio_desc        *gpio_data;
  29         struct gpio_desc        *gpio_trans;    /* Voltage translator */
  30         struct gpio_desc        *gpio_enable;   /* FSI enable */
  31         struct gpio_desc        *gpio_mux;      /* Mux control */
  32         bool                    external_mode;
  33         bool                    no_delays;
  34         uint32_t                last_addr;
  35         uint8_t                 t_send_delay;
  36         uint8_t                 t_echo_delay;
  37 };
  38
  39 #define CREATE_TRACE_POINTS
  40 #include <trace/events/fsi_master_gpio.h>
  41
  42 #define to_fsi_master_gpio(m) container_of(m, struct fsi_master_gpio, master)
  43
  44 struct fsi_gpio_msg {
  45         uint64_t        msg;
  46         uint8_t         bits;
  47 };
  48
  49 static void clock_toggle(struct fsi_master_gpio *master, int count)
  50 {
  51         int i;
  52
  53         for (i = 0; i < count; i++) {
  54                 if (!master->no_delays)
  55                         ndelay(FSI_GPIO_STD_DLY);
  56                 gpiod_set_value(master->gpio_clk, 0);
  57                 if (!master->no_delays)
  58                         ndelay(FSI_GPIO_STD_DLY);
  59                 gpiod_set_value(master->gpio_clk, 1);
  60         }
  61 }
  62
  63 static int sda_clock_in(struct fsi_master_gpio *master)
  64 {
  65         int in;
  66
  67         if (!master->no_delays)
  68                 ndelay(FSI_GPIO_STD_DLY);
  69         gpiod_set_value(master->gpio_clk, 0);
  70
  71         /* Dummy read to feed the synchronizers */
  72         gpiod_get_value(master->gpio_data);
  73
  74         /* Actual data read */
  75         in = gpiod_get_value(master->gpio_data);
  76         if (!master->no_delays)
  77                 ndelay(FSI_GPIO_STD_DLY);
  78         gpiod_set_value(master->gpio_clk, 1);
  79         return in ? 1 : 0;
  80 }
  81
  82 static void sda_out(struct fsi_master_gpio *master, int value)
  83 {
  84         gpiod_set_value(master->gpio_data, value);
  85 }
  86
  87 static void set_sda_input(struct fsi_master_gpio *master)
  88 {
  89         gpiod_direction_input(master->gpio_data);
  90         gpiod_set_value(master->gpio_trans, 0);
  91 }
  92
  93 static void set_sda_output(struct fsi_master_gpio *master, int value)
  94 {
  95         gpiod_set_value(master->gpio_trans, 1);
  96         gpiod_direction_output(master->gpio_data, value);
  97 }
  98
  99 static void clock_zeros(struct fsi_master_gpio *master, int count)
 100 {
 101         trace_fsi_master_gpio_clock_zeros(master, count);
 102         set_sda_output(master, 1);
 103         clock_toggle(master, count);
 104 }
 105
 106 static void echo_delay(struct fsi_master_gpio *master)
 107 {
 108         clock_zeros(master, master->t_echo_delay);
 109 }
 110
 111
 112 static void serial_in(struct fsi_master_gpio *master, struct fsi_gpio_msg *msg,
 113                         uint8_t num_bits)
 114 {
 115         uint8_t bit, in_bit;
 116
 117         set_sda_input(master);
 118
 119         for (bit = 0; bit < num_bits; bit++) {
 120                 in_bit = sda_clock_in(master);
 121                 msg->msg <<= 1;
 122                 msg->msg |= ~in_bit & 0x1;      /* Data is active low */
 123         }
 124         msg->bits += num_bits;
 125
 126         trace_fsi_master_gpio_in(master, num_bits, msg->msg);
 127 }
 128
 129 static void serial_out(struct fsi_master_gpio *master,
 130                         const struct fsi_gpio_msg *cmd)
 131 {
 132         uint8_t bit;
 133         uint64_t msg = ~cmd->msg;       /* Data is active low */
 134         uint64_t sda_mask = 0x1ULL << (cmd->bits - 1);
 135         uint64_t last_bit = ~0;
 136         int next_bit;
 137
 138         trace_fsi_master_gpio_out(master, cmd->bits, cmd->msg);
 139
 140         if (!cmd->bits) {
 141                 dev_warn(master->dev, "trying to output 0 bits\n");
 142                 return;
 143         }
 144         set_sda_output(master, 0);
 145
 146         /* Send the start bit */
 147         sda_out(master, 0);
 148         clock_toggle(master, 1);
 149
 150         /* Send the message */
 151         for (bit = 0; bit < cmd->bits; bit++) {
 152                 next_bit = (msg & sda_mask) >> (cmd->bits - 1);
 153                 if (last_bit ^ next_bit) {
 154                         sda_out(master, next_bit);
 155                         last_bit = next_bit;
 156                 }
 157                 clock_toggle(master, 1);
 158                 msg <<= 1;
 159         }
 160 }
 161
 162 static void msg_push_bits(struct fsi_gpio_msg *msg, uint64_t data, int bits)
 163 {
 164         msg->msg <<= bits;
 165         msg->msg |= data & ((1ull << bits) - 1);
 166         msg->bits += bits;
 167 }
 168
 169 static void msg_push_crc(struct fsi_gpio_msg *msg)
 170 {
 171         uint8_t crc;
 172         int top;
 173
 174         top = msg->bits & 0x3;
 175
 176         /* start bit, and any non-aligned top bits */
 177         crc = crc4(0, 1 << top | msg->msg >> (msg->bits - top), top + 1);
 178
 179         /* aligned bits */
 180         crc = crc4(crc, msg->msg, msg->bits - top);
 181
 182         msg_push_bits(msg, crc, 4);
 183 }
 184
 185 static bool check_same_address(struct fsi_master_gpio *master, int id,
 186                 uint32_t addr)
 187 {
 188         /* this will also handle LAST_ADDR_INVALID */
 189         return master->last_addr == (((id & 0x3) << 21) | (addr & ~0x3));
 190 }
 191
 192 static bool check_relative_address(struct fsi_master_gpio *master, int id,
 193                 uint32_t addr, uint32_t *rel_addrp)
 194 {
 195         uint32_t last_addr = master->last_addr;
 196         int32_t rel_addr;
 197
 198         if (last_addr == LAST_ADDR_INVALID)
 199                 return false;
 200
 201         /* We may be in 23-bit addressing mode, which uses the id as the
 202          * top two address bits. So, if we're referencing a different ID,
 203          * use absolute addresses.
 204          */
 205         if (((last_addr >> 21) & 0x3) != id)
 206                 return false;
 207
 208         /* remove the top two bits from any 23-bit addressing */
 209         last_addr &= (1 << 21) - 1;
 210
 211         /* We know that the addresses are limited to 21 bits, so this won't
 212          * overflow the signed rel_addr */
 213         rel_addr = addr - last_addr;
 214         if (rel_addr > 255 || rel_addr < -256)
 215                 return false;
 216
 217         *rel_addrp = (uint32_t)rel_addr;
 218
 219         return true;
 220 }
 221
 222 static void last_address_update(struct fsi_master_gpio *master,
 223                 int id, bool valid, uint32_t addr)
 224 {
 225         if (!valid)
 226                 master->last_addr = LAST_ADDR_INVALID;
 227         else
 228                 master->last_addr = ((id & 0x3) << 21) | (addr & ~0x3);
 229 }
 230
 231 /*
 232  * Encode an Absolute/Relative/Same Address command
 233  */
 234 static void build_ar_command(struct fsi_master_gpio *master,
 235                 struct fsi_gpio_msg *cmd, uint8_t id,
 236                 uint32_t addr, size_t size, const void *data)
 237 {
 238         int i, addr_bits, opcode_bits;
 239         bool write = !!data;
 240         uint8_t ds, opcode;
 241         uint32_t rel_addr;
 242
 243         cmd->bits = 0;
 244         cmd->msg = 0;
 245
 246         /* we have 21 bits of address max */
 247         addr &= ((1 << 21) - 1);
 248
 249         /* cmd opcodes are variable length - SAME_AR is only two bits */
 250         opcode_bits = 3;
 251
 252         if (check_same_address(master, id, addr)) {
 253                 /* we still address the byte offset within the word */
 254                 addr_bits = 2;
 255                 opcode_bits = 2;
 256                 opcode = FSI_CMD_SAME_AR;
 257                 trace_fsi_master_gpio_cmd_same_addr(master);
 258
 259         } else if (check_relative_address(master, id, addr, &rel_addr)) {
 260                 /* 8 bits plus sign */
 261                 addr_bits = 9;
 262                 addr = rel_addr;
 263                 opcode = FSI_CMD_REL_AR;
 264                 trace_fsi_master_gpio_cmd_rel_addr(master, rel_addr);
 265
 266         } else {
 267                 addr_bits = 21;
 268                 opcode = FSI_CMD_ABS_AR;
 269                 trace_fsi_master_gpio_cmd_abs_addr(master, addr);
 270         }
 271
 272         /*
 273          * The read/write size is encoded in the lower bits of the address
 274          * (as it must be naturally-aligned), and the following ds bit.
 275          *
 276          *      size    addr:1  addr:0  ds
 277          *      1       x       x       0
 278          *      2       x       0       1
 279          *      4       0       1       1
 280          *
 281          */
 282         ds = size > 1 ? 1 : 0;
 283         addr &= ~(size - 1);
 284         if (size == 4)
 285                 addr |= 1;
 286
 287         msg_push_bits(cmd, id, 2);
 288         msg_push_bits(cmd, opcode, opcode_bits);
 289         msg_push_bits(cmd, write ? 0 : 1, 1);
 290         msg_push_bits(cmd, addr, addr_bits);
 291         msg_push_bits(cmd, ds, 1);
 292         for (i = 0; write && i < size; i++)
 293                 msg_push_bits(cmd, ((uint8_t *)data)[i], 8);
 294
 295         msg_push_crc(cmd);
 296 }
 297
 298 static void build_dpoll_command(struct fsi_gpio_msg *cmd, uint8_t slave_id)
 299 {
 300         cmd->bits = 0;
 301         cmd->msg = 0;
 302
 303         msg_push_bits(cmd, slave_id, 2);
 304         msg_push_bits(cmd, FSI_CMD_DPOLL, 3);
 305         msg_push_crc(cmd);
 306 }
 307
 308 static void build_epoll_command(struct fsi_gpio_msg *cmd, uint8_t slave_id)
 309 {
 310         cmd->bits = 0;
 311         cmd->msg = 0;
 312
 313         msg_push_bits(cmd, slave_id, 2);
 314         msg_push_bits(cmd, FSI_CMD_EPOLL, 3);
 315         msg_push_crc(cmd);
 316 }
 317
 318 static void build_term_command(struct fsi_gpio_msg *cmd, uint8_t slave_id)
 319 {
 320         cmd->bits = 0;
 321         cmd->msg = 0;
 322
 323         msg_push_bits(cmd, slave_id, 2);
 324         msg_push_bits(cmd, FSI_CMD_TERM, 6);
 325         msg_push_crc(cmd);
 326 }
 327
 328 /*
 329  * Note: callers rely specifically on this returning -EAGAIN for
 330  * a CRC error detected in the response. Use other error code
 331  * for other situations. It will be converted to something else
 332  * higher up the stack before it reaches userspace.
 333  */
 334 static int read_one_response(struct fsi_master_gpio *master,
 335                 uint8_t data_size, struct fsi_gpio_msg *msgp, uint8_t *tagp)
 336 {
 337         struct fsi_gpio_msg msg;
 338         unsigned long flags;
 339         uint32_t crc;
 340         uint8_t tag;
 341         int i;
 342
 343         local_irq_save(flags);
 344
 345         /* wait for the start bit */
 346         for (i = 0; i < FSI_MASTER_MTOE_COUNT; i++) {
 347                 msg.bits = 0;
 348                 msg.msg = 0;
 349                 serial_in(master, &msg, 1);
 350                 if (msg.msg)
 351                         break;
 352         }
 353         if (i == FSI_MASTER_MTOE_COUNT) {
 354                 dev_dbg(master->dev,
 355                         "Master time out waiting for response\n");
 356                 local_irq_restore(flags);
 357                 return -ETIMEDOUT;
 358         }
 359
 360         msg.bits = 0;
 361         msg.msg = 0;
 362
 363         /* Read slave ID & response tag */
 364         serial_in(master, &msg, 4);
 365
 366         tag = msg.msg & 0x3;
 367
 368         /* If we have an ACK and we're expecting data, clock the data in too */
 369         if (tag == FSI_RESP_ACK && data_size)
 370                 serial_in(master, &msg, data_size * 8);
 371
 372         /* read CRC */
 373         serial_in(master, &msg, FSI_CRC_SIZE);
 374
 375         local_irq_restore(flags);
 376
 377         /* we have a whole message now; check CRC */
 378         crc = crc4(0, 1, 1);
 379         crc = crc4(crc, msg.msg, msg.bits);
 380         if (crc) {
 381                 /* Check if it's all 1's, that probably means the host is off */
 382                 if (((~msg.msg) & ((1ull << msg.bits) - 1)) == 0)
 383                         return -ENODEV;
 384                 dev_dbg(master->dev, "ERR response CRC msg: 0x%016llx (%d bits)\n",
 385                         msg.msg, msg.bits);
 386                 return -EAGAIN;
 387         }
 388
 389         if (msgp)
 390                 *msgp = msg;
 391         if (tagp)
 392                 *tagp = tag;
 393
 394         return 0;
 395 }
 396
 397 static int issue_term(struct fsi_master_gpio *master, uint8_t slave)
 398 {
 399         struct fsi_gpio_msg cmd;
 400         unsigned long flags;
 401         uint8_t tag;
 402         int rc;
 403
 404         build_term_command(&cmd, slave);
 405
 406         local_irq_save(flags);
 407         serial_out(master, &cmd);
 408         echo_delay(master);
 409         local_irq_restore(flags);
 410
 411         rc = read_one_response(master, 0, NULL, &tag);
 412         if (rc < 0) {
 413                 dev_err(master->dev,
 414                                 "TERM failed; lost communication with slave\n");
 415                 return -EIO;
 416         } else if (tag != FSI_RESP_ACK) {
 417                 dev_err(master->dev, "TERM failed; response %d\n", tag);
 418                 return -EIO;
 419         }
 420
 421         return 0;
 422 }
 423
 424 static int poll_for_response(struct fsi_master_gpio *master,
 425                 uint8_t slave, uint8_t size, void *data)
 426 {
 427         struct fsi_gpio_msg response, cmd;
 428         int busy_count = 0, rc, i;
 429         unsigned long flags;
 430         uint8_t tag;
 431         uint8_t *data_byte = data;
 432         int crc_err_retries = 0;
 433 retry:
 434         rc = read_one_response(master, size, &response, &tag);
 435
 436         /* Handle retries on CRC errors */
 437         if (rc == -EAGAIN) {
 438                 /* Too many retries ? */
 439                 if (crc_err_retries++ > FSI_CRC_ERR_RETRIES) {
 440                         /*
 441                          * Pass it up as a -EIO otherwise upper level will retry
 442                          * the whole command which isn't what we want here.
 443                          */
 444                         rc = -EIO;
 445                         goto fail;
 446                 }
 447                 dev_dbg(master->dev,
 448                          "CRC error retry %d\n", crc_err_retries);
 449                 trace_fsi_master_gpio_crc_rsp_error(master);
 450                 build_epoll_command(&cmd, slave);
 451                 local_irq_save(flags);
 452                 clock_zeros(master, FSI_MASTER_EPOLL_CLOCKS);
 453                 serial_out(master, &cmd);
 454                 echo_delay(master);
 455                 local_irq_restore(flags);
 456                 goto retry;
 457         } else if (rc)
 458                 goto fail;
 459
 460         switch (tag) {
 461         case FSI_RESP_ACK:
 462                 if (size && data) {
 463                         uint64_t val = response.msg;
 464                         /* clear crc & mask */
 465                         val >>= 4;
 466                         val &= (1ull << (size * 8)) - 1;
 467
 468                         for (i = 0; i < size; i++) {
 469                                 data_byte[size-i-1] = val;
 470                                 val >>= 8;
 471                         }
 472                 }
 473                 break;
 474         case FSI_RESP_BUSY:
 475                 /*
 476                  * Its necessary to clock slave before issuing
 477                  * d-poll, not indicated in the hardware protocol
 478                  * spec. < 20 clocks causes slave to hang, 21 ok.
 479                  */
 480                 if (busy_count++ < FSI_MASTER_MAX_BUSY) {
 481                         build_dpoll_command(&cmd, slave);
 482                         local_irq_save(flags);
 483                         clock_zeros(master, FSI_MASTER_DPOLL_CLOCKS);
 484                         serial_out(master, &cmd);
 485                         echo_delay(master);
 486                         local_irq_restore(flags);
 487                         goto retry;
 488                 }
 489                 dev_warn(master->dev,
 490                         "ERR slave is stuck in busy state, issuing TERM\n");
 491                 local_irq_save(flags);
 492                 clock_zeros(master, FSI_MASTER_DPOLL_CLOCKS);
 493                 local_irq_restore(flags);
 494                 issue_term(master, slave);
 495                 rc = -EIO;
 496                 break;
 497
 498         case FSI_RESP_ERRA:
 499                 dev_dbg(master->dev, "ERRA received: 0x%x\n", (int)response.msg);
 500                 rc = -EIO;
 501                 break;
 502         case FSI_RESP_ERRC:
 503                 dev_dbg(master->dev, "ERRC received: 0x%x\n", (int)response.msg);
 504                 trace_fsi_master_gpio_crc_cmd_error(master);
 505                 rc = -EAGAIN;
 506                 break;
 507         }
 508
 509         if (busy_count > 0)
 510                 trace_fsi_master_gpio_poll_response_busy(master, busy_count);
 511  fail:
 512         /*
 513          * tSendDelay clocks, avoids signal reflections when switching
 514          * from receive of response back to send of data.
 515          */
 516         local_irq_save(flags);
 517         clock_zeros(master, master->t_send_delay);
 518         local_irq_restore(flags);
 519
 520         return rc;
 521 }
 522
 523 static int send_request(struct fsi_master_gpio *master,
 524                 struct fsi_gpio_msg *cmd)
 525 {
 526         unsigned long flags;
 527
 528         if (master->external_mode)
 529                 return -EBUSY;
 530
 531         local_irq_save(flags);
 532         serial_out(master, cmd);
 533         echo_delay(master);
 534         local_irq_restore(flags);
 535
 536         return 0;
 537 }
 538
 539 static int fsi_master_gpio_xfer(struct fsi_master_gpio *master, uint8_t slave,
 540                 struct fsi_gpio_msg *cmd, size_t resp_len, void *resp)
 541 {
 542         int rc = -EAGAIN, retries = 0;
 543
 544         while ((retries++) < FSI_CRC_ERR_RETRIES) {
 545                 rc = send_request(master, cmd);
 546                 if (rc)
 547                         break;
 548                 rc = poll_for_response(master, slave, resp_len, resp);
 549                 if (rc != -EAGAIN)
 550                         break;
 551                 rc = -EIO;
 552                 dev_warn(master->dev, "ECRC retry %d\n", retries);
 553
 554                 /* Pace it a bit before retry */
 555                 msleep(1);
 556         }
 557
 558         return rc;
 559 }
 560
 561 static int fsi_master_gpio_read(struct fsi_master *_master, int link,
 562                 uint8_t id, uint32_t addr, void *val, size_t size)
 563 {
 564         struct fsi_master_gpio *master = to_fsi_master_gpio(_master);
 565         struct fsi_gpio_msg cmd;
 566         int rc;
 567
 568         if (link != 0)
 569                 return -ENODEV;
 570
 571         mutex_lock(&master->cmd_lock);
 572         build_ar_command(master, &cmd, id, addr, size, NULL);
 573         rc = fsi_master_gpio_xfer(master, id, &cmd, size, val);
 574         last_address_update(master, id, rc == 0, addr);
 575         mutex_unlock(&master->cmd_lock);
 576
 577         return rc;
 578 }
 579
 580 static int fsi_master_gpio_write(struct fsi_master *_master, int link,
 581                 uint8_t id, uint32_t addr, const void *val, size_t size)
 582 {
 583         struct fsi_master_gpio *master = to_fsi_master_gpio(_master);
 584         struct fsi_gpio_msg cmd;
 585         int rc;
 586
 587         if (link != 0)
 588                 return -ENODEV;
 589
 590         mutex_lock(&master->cmd_lock);
 591         build_ar_command(master, &cmd, id, addr, size, val);
 592         rc = fsi_master_gpio_xfer(master, id, &cmd, 0, NULL);
 593         last_address_update(master, id, rc == 0, addr);
 594         mutex_unlock(&master->cmd_lock);
 595
 596         return rc;
 597 }
 598
 599 static int fsi_master_gpio_term(struct fsi_master *_master,
 600                 int link, uint8_t id)
 601 {
 602         struct fsi_master_gpio *master = to_fsi_master_gpio(_master);
 603         struct fsi_gpio_msg cmd;
 604         int rc;
 605
 606         if (link != 0)
 607                 return -ENODEV;
 608
 609         mutex_lock(&master->cmd_lock);
 610         build_term_command(&cmd, id);
 611         rc = fsi_master_gpio_xfer(master, id, &cmd, 0, NULL);
 612         last_address_update(master, id, false, 0);
 613         mutex_unlock(&master->cmd_lock);
 614
 615         return rc;
 616 }
 617
 618 static int fsi_master_gpio_break(struct fsi_master *_master, int link)
 619 {
 620         struct fsi_master_gpio *master = to_fsi_master_gpio(_master);
 621         unsigned long flags;
 622
 623         if (link != 0)
 624                 return -ENODEV;
 625
 626         trace_fsi_master_gpio_break(master);
 627
 628         mutex_lock(&master->cmd_lock);
 629         if (master->external_mode) {
 630                 mutex_unlock(&master->cmd_lock);
 631                 return -EBUSY;
 632         }
 633
 634         local_irq_save(flags);
 635
 636         set_sda_output(master, 1);
 637         sda_out(master, 1);
 638         clock_toggle(master, FSI_PRE_BREAK_CLOCKS);
 639         sda_out(master, 0);
 640         clock_toggle(master, FSI_BREAK_CLOCKS);
 641         echo_delay(master);
 642         sda_out(master, 1);
 643         clock_toggle(master, FSI_POST_BREAK_CLOCKS);
 644
 645         local_irq_restore(flags);
 646
 647         last_address_update(master, 0, false, 0);
 648         mutex_unlock(&master->cmd_lock);
 649
 650         /* Wait for logic reset to take effect */
 651         udelay(200);
 652
 653         return 0;
 654 }
 655
 656 static void fsi_master_gpio_init(struct fsi_master_gpio *master)
 657 {
 658         unsigned long flags;
 659
 660         gpiod_direction_output(master->gpio_mux, 1);
 661         gpiod_direction_output(master->gpio_trans, 1);
 662         gpiod_direction_output(master->gpio_enable, 1);
 663         gpiod_direction_output(master->gpio_clk, 1);
 664         gpiod_direction_output(master->gpio_data, 1);
 665
 666         /* todo: evaluate if clocks can be reduced */
 667         local_irq_save(flags);
 668         clock_zeros(master, FSI_INIT_CLOCKS);
 669         local_irq_restore(flags);
 670 }
 671
 672 static void fsi_master_gpio_init_external(struct fsi_master_gpio *master)
 673 {
 674         gpiod_direction_output(master->gpio_mux, 0);
 675         gpiod_direction_output(master->gpio_trans, 0);
 676         gpiod_direction_output(master->gpio_enable, 1);
 677         gpiod_direction_input(master->gpio_clk);
 678         gpiod_direction_input(master->gpio_data);
 679 }
 680
 681 static int fsi_master_gpio_link_enable(struct fsi_master *_master, int link)
 682 {
 683         struct fsi_master_gpio *master = to_fsi_master_gpio(_master);
 684         int rc = -EBUSY;
 685
 686         if (link != 0)
 687                 return -ENODEV;
 688
 689         mutex_lock(&master->cmd_lock);
 690         if (!master->external_mode) {
 691                 gpiod_set_value(master->gpio_enable, 1);
 692                 rc = 0;
 693         }
 694         mutex_unlock(&master->cmd_lock);
 695
 696         return rc;
 697 }
 698
 699 static int fsi_master_gpio_link_config(struct fsi_master *_master, int link,
 700                                        u8 t_send_delay, u8 t_echo_delay)
 701 {
 702         struct fsi_master_gpio *master = to_fsi_master_gpio(_master);
 703
 704         if (link != 0)
 705                 return -ENODEV;
 706
 707         mutex_lock(&master->cmd_lock);
 708         master->t_send_delay = t_send_delay;
 709         master->t_echo_delay = t_echo_delay;
 710         mutex_unlock(&master->cmd_lock);
 711
 712         return 0;
 713 }
 714
 715 static ssize_t external_mode_show(struct device *dev,
 716                 struct device_attribute *attr, char *buf)
 717 {
 718         struct fsi_master_gpio *master = dev_get_drvdata(dev);
 719
 720         return snprintf(buf, PAGE_SIZE - 1, "%u\n",
 721                         master->external_mode ? 1 : 0);
 722 }
 723
 724 static ssize_t external_mode_store(struct device *dev,
 725                 struct device_attribute *attr, const char *buf, size_t count)
 726 {
 727         struct fsi_master_gpio *master = dev_get_drvdata(dev);
 728         unsigned long val;
 729         bool external_mode;
 730         int err;
 731
 732         err = kstrtoul(buf, 0, &val);
 733         if (err)
 734                 return err;
 735
 736         external_mode = !!val;
 737
 738         mutex_lock(&master->cmd_lock);
 739
 740         if (external_mode == master->external_mode) {
 741                 mutex_unlock(&master->cmd_lock);
 742                 return count;
 743         }
 744
 745         master->external_mode = external_mode;
 746         if (master->external_mode)
 747                 fsi_master_gpio_init_external(master);
 748         else
 749                 fsi_master_gpio_init(master);
 750
 751         mutex_unlock(&master->cmd_lock);
 752
 753         fsi_master_rescan(&master->master);
 754
 755         return count;
 756 }
 757
 758 static DEVICE_ATTR(external_mode, 0664,
 759                 external_mode_show, external_mode_store);
 760
 761 static void fsi_master_gpio_release(struct device *dev)
 762 {
 763         struct fsi_master_gpio *master = to_fsi_master_gpio(dev_to_fsi_master(dev));
 764
 765         of_node_put(dev_of_node(master->dev));
 766
 767         kfree(master);
 768 }
 769
 770 static int fsi_master_gpio_probe(struct platform_device *pdev)
 771 {
 772         struct fsi_master_gpio *master;
 773         struct gpio_desc *gpio;
 774         int rc;
 775
 776         master = kzalloc(sizeof(*master), GFP_KERNEL);
 777         if (!master)
 778                 return -ENOMEM;
 779
 780         master->dev = &pdev->dev;
 781         master->master.dev.parent = master->dev;
 782         master->master.dev.of_node = of_node_get(dev_of_node(master->dev));
 783         master->master.dev.release = fsi_master_gpio_release;
 784         master->last_addr = LAST_ADDR_INVALID;
 785
 786         gpio = devm_gpiod_get(&pdev->dev, "clock", 0);
 787         if (IS_ERR(gpio)) {
 788                 dev_err(&pdev->dev, "failed to get clock gpio\n");
 789                 rc = PTR_ERR(gpio);
 790                 goto err_free;
 791         }
 792         master->gpio_clk = gpio;
 793
 794         gpio = devm_gpiod_get(&pdev->dev, "data", 0);
 795         if (IS_ERR(gpio)) {
 796                 dev_err(&pdev->dev, "failed to get data gpio\n");
 797                 rc = PTR_ERR(gpio);
 798                 goto err_free;
 799         }
 800         master->gpio_data = gpio;
 801
 802         /* Optional GPIOs */
 803         gpio = devm_gpiod_get_optional(&pdev->dev, "trans", 0);
 804         if (IS_ERR(gpio)) {
 805                 dev_err(&pdev->dev, "failed to get trans gpio\n");
 806                 rc = PTR_ERR(gpio);
 807                 goto err_free;
 808         }
 809         master->gpio_trans = gpio;
 810
 811         gpio = devm_gpiod_get_optional(&pdev->dev, "enable", 0);
 812         if (IS_ERR(gpio)) {
 813                 dev_err(&pdev->dev, "failed to get enable gpio\n");
 814                 rc = PTR_ERR(gpio);
 815                 goto err_free;
 816         }
 817         master->gpio_enable = gpio;
 818
 819         gpio = devm_gpiod_get_optional(&pdev->dev, "mux", 0);
 820         if (IS_ERR(gpio)) {
 821                 dev_err(&pdev->dev, "failed to get mux gpio\n");
 822                 rc = PTR_ERR(gpio);
 823                 goto err_free;
 824         }
 825         master->gpio_mux = gpio;
 826
 827         /*
 828          * Check if GPIO block is slow enought that no extra delays
 829          * are necessary. This improves performance on ast2500 by
 830          * an order of magnitude.
 831          */
 832         master->no_delays = device_property_present(&pdev->dev, "no-gpio-delays");
 833
 834         /* Default FSI command delays */
 835         master->t_send_delay = FSI_SEND_DELAY_CLOCKS;
 836         master->t_echo_delay = FSI_ECHO_DELAY_CLOCKS;
 837
 838         master->master.n_links = 1;
 839         master->master.flags = FSI_MASTER_FLAG_SWCLOCK;
 840         master->master.read = fsi_master_gpio_read;
 841         master->master.write = fsi_master_gpio_write;
 842         master->master.term = fsi_master_gpio_term;
 843         master->master.send_break = fsi_master_gpio_break;
 844         master->master.link_enable = fsi_master_gpio_link_enable;
 845         master->master.link_config = fsi_master_gpio_link_config;
 846         platform_set_drvdata(pdev, master);
 847         mutex_init(&master->cmd_lock);
 848
 849         fsi_master_gpio_init(master);
 850
 851         rc = device_create_file(&pdev->dev, &dev_attr_external_mode);
 852         if (rc)
 853                 goto err_free;
 854
 855         rc = fsi_master_register(&master->master);
 856         if (rc) {
 857                 device_remove_file(&pdev->dev, &dev_attr_external_mode);
 858                 put_device(&master->master.dev);
 859                 return rc;
 860         }
 861         return 0;
 862  err_free:
 863         kfree(master);
 864         return rc;
 865 }
 866
 867
 868
 869 static int fsi_master_gpio_remove(struct platform_device *pdev)
 870 {
 871         struct fsi_master_gpio *master = platform_get_drvdata(pdev);
 872
 873         device_remove_file(&pdev->dev, &dev_attr_external_mode);
 874
 875         fsi_master_unregister(&master->master);
 876
 877         return 0;
 878 }
 879
 880 static const struct of_device_id fsi_master_gpio_match[] = {
 881         { .compatible = "fsi-master-gpio" },
 882         { },
 883 };
 884
 885 static struct platform_driver fsi_master_gpio_driver = {
 886         .driver = {
 887                 .name           = "fsi-master-gpio",
 888                 .of_match_table = fsi_master_gpio_match,
 889         },
 890         .probe  = fsi_master_gpio_probe,
 891         .remove = fsi_master_gpio_remove,
 892 };
 893
 894 module_platform_driver(fsi_master_gpio_driver);
 895 MODULE_LICENSE("GPL");