drivers/fsi/fsi-master-gpio.c

   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");