linux/drivers/fsi/fsi-master-gpio.c
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   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
  23struct 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
  44struct fsi_gpio_msg {
  45        uint64_t        msg;
  46        uint8_t         bits;
  47};
  48
  49static 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
  63static 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
  82static void sda_out(struct fsi_master_gpio *master, int value)
  83{
  84        gpiod_set_value(master->gpio_data, value);
  85}
  86
  87static 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
  93static 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
  99static 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
 106static void echo_delay(struct fsi_master_gpio *master)
 107{
 108        clock_zeros(master, master->t_echo_delay);
 109}
 110
 111
 112static 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
 129static 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
 162static 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
 169static 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
 185static 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
 192static 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
 222static 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 */
 234static 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
 298static 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
 308static 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
 318static 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 */
 334static 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
 397static 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
 424static 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;
 433retry:
 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
 523static 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
 539static 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
 561static 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
 580static 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
 599static 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
 618static 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
 656static 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
 672static 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
 681static 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
 699static 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
 715static 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
 724static 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
 758static DEVICE_ATTR(external_mode, 0664,
 759                external_mode_show, external_mode_store);
 760
 761static 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
 770static 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
 869static 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
 880static const struct of_device_id fsi_master_gpio_match[] = {
 881        { .compatible = "fsi-master-gpio" },
 882        { },
 883};
 884
 885static 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
 894module_platform_driver(fsi_master_gpio_driver);
 895MODULE_LICENSE("GPL");
 896