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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * A FSI master controller, using a simple GPIO bit-banging interface4 */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 0x122 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_POINTS40#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 the202 * 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't212 * 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 else228 master->last_addr = ((id & 0x3) << 21) | (addr & ~0x3);229}230 231/*232 * Encode an Absolute/Relative/Same Address command233 */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 address274 * (as it must be naturally-aligned), and the following ds bit.275 *276 * size addr:1 addr:0 ds277 * 1 x x 0278 * 2 x 0 1279 * 4 0 1 1280 *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 for330 * a CRC error detected in the response. Use other error code331 * for other situations. It will be converted to something else332 * 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 retry442 * 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 issuing477 * d-poll, not indicated in the hardware protocol478 * 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 switching514 * 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 bool enable)683{684 struct fsi_master_gpio *master = to_fsi_master_gpio(_master);685 int rc = -EBUSY;686 687 if (link != 0)688 return -ENODEV;689 690 mutex_lock(&master->cmd_lock);691 if (!master->external_mode) {692 gpiod_set_value(master->gpio_enable, enable ? 1 : 0);693 rc = 0;694 }695 mutex_unlock(&master->cmd_lock);696 697 return rc;698}699 700static int fsi_master_gpio_link_config(struct fsi_master *_master, int link,701 u8 t_send_delay, u8 t_echo_delay)702{703 struct fsi_master_gpio *master = to_fsi_master_gpio(_master);704 705 if (link != 0)706 return -ENODEV;707 708 mutex_lock(&master->cmd_lock);709 master->t_send_delay = t_send_delay;710 master->t_echo_delay = t_echo_delay;711 mutex_unlock(&master->cmd_lock);712 713 return 0;714}715 716static ssize_t external_mode_show(struct device *dev,717 struct device_attribute *attr, char *buf)718{719 struct fsi_master_gpio *master = dev_get_drvdata(dev);720 721 return snprintf(buf, PAGE_SIZE - 1, "%u\n",722 master->external_mode ? 1 : 0);723}724 725static ssize_t external_mode_store(struct device *dev,726 struct device_attribute *attr, const char *buf, size_t count)727{728 struct fsi_master_gpio *master = dev_get_drvdata(dev);729 unsigned long val;730 bool external_mode;731 int err;732 733 err = kstrtoul(buf, 0, &val);734 if (err)735 return err;736 737 external_mode = !!val;738 739 mutex_lock(&master->cmd_lock);740 741 if (external_mode == master->external_mode) {742 mutex_unlock(&master->cmd_lock);743 return count;744 }745 746 master->external_mode = external_mode;747 if (master->external_mode)748 fsi_master_gpio_init_external(master);749 else750 fsi_master_gpio_init(master);751 752 mutex_unlock(&master->cmd_lock);753 754 fsi_master_rescan(&master->master);755 756 return count;757}758 759static DEVICE_ATTR(external_mode, 0664,760 external_mode_show, external_mode_store);761 762static void fsi_master_gpio_release(struct device *dev)763{764 struct fsi_master_gpio *master = to_fsi_master_gpio(to_fsi_master(dev));765 766 of_node_put(dev_of_node(master->dev));767 768 kfree(master);769}770 771static int fsi_master_gpio_probe(struct platform_device *pdev)772{773 struct fsi_master_gpio *master;774 struct gpio_desc *gpio;775 int rc;776 777 master = kzalloc(sizeof(*master), GFP_KERNEL);778 if (!master)779 return -ENOMEM;780 781 master->dev = &pdev->dev;782 master->master.dev.parent = master->dev;783 master->master.dev.of_node = of_node_get(dev_of_node(master->dev));784 master->master.dev.release = fsi_master_gpio_release;785 master->last_addr = LAST_ADDR_INVALID;786 787 gpio = devm_gpiod_get(&pdev->dev, "clock", 0);788 if (IS_ERR(gpio)) {789 dev_err(&pdev->dev, "failed to get clock gpio\n");790 rc = PTR_ERR(gpio);791 goto err_free;792 }793 master->gpio_clk = gpio;794 795 gpio = devm_gpiod_get(&pdev->dev, "data", 0);796 if (IS_ERR(gpio)) {797 dev_err(&pdev->dev, "failed to get data gpio\n");798 rc = PTR_ERR(gpio);799 goto err_free;800 }801 master->gpio_data = gpio;802 803 /* Optional GPIOs */804 gpio = devm_gpiod_get_optional(&pdev->dev, "trans", 0);805 if (IS_ERR(gpio)) {806 dev_err(&pdev->dev, "failed to get trans gpio\n");807 rc = PTR_ERR(gpio);808 goto err_free;809 }810 master->gpio_trans = gpio;811 812 gpio = devm_gpiod_get_optional(&pdev->dev, "enable", 0);813 if (IS_ERR(gpio)) {814 dev_err(&pdev->dev, "failed to get enable gpio\n");815 rc = PTR_ERR(gpio);816 goto err_free;817 }818 master->gpio_enable = gpio;819 820 gpio = devm_gpiod_get_optional(&pdev->dev, "mux", 0);821 if (IS_ERR(gpio)) {822 dev_err(&pdev->dev, "failed to get mux gpio\n");823 rc = PTR_ERR(gpio);824 goto err_free;825 }826 master->gpio_mux = gpio;827 828 /*829 * Check if GPIO block is slow enought that no extra delays830 * are necessary. This improves performance on ast2500 by831 * an order of magnitude.832 */833 master->no_delays = device_property_present(&pdev->dev, "no-gpio-delays");834 835 /* Default FSI command delays */836 master->t_send_delay = FSI_SEND_DELAY_CLOCKS;837 master->t_echo_delay = FSI_ECHO_DELAY_CLOCKS;838 839 master->master.n_links = 1;840 master->master.flags = FSI_MASTER_FLAG_SWCLOCK;841 master->master.read = fsi_master_gpio_read;842 master->master.write = fsi_master_gpio_write;843 master->master.term = fsi_master_gpio_term;844 master->master.send_break = fsi_master_gpio_break;845 master->master.link_enable = fsi_master_gpio_link_enable;846 master->master.link_config = fsi_master_gpio_link_config;847 platform_set_drvdata(pdev, master);848 mutex_init(&master->cmd_lock);849 850 fsi_master_gpio_init(master);851 852 rc = device_create_file(&pdev->dev, &dev_attr_external_mode);853 if (rc)854 goto err_free;855 856 rc = fsi_master_register(&master->master);857 if (rc) {858 device_remove_file(&pdev->dev, &dev_attr_external_mode);859 put_device(&master->master.dev);860 return rc;861 }862 return 0;863 err_free:864 kfree(master);865 return rc;866}867 868 869 870static void fsi_master_gpio_remove(struct platform_device *pdev)871{872 struct fsi_master_gpio *master = platform_get_drvdata(pdev);873 874 device_remove_file(&pdev->dev, &dev_attr_external_mode);875 876 fsi_master_unregister(&master->master);877}878 879static const struct of_device_id fsi_master_gpio_match[] = {880 { .compatible = "fsi-master-gpio" },881 { },882};883MODULE_DEVICE_TABLE(of, fsi_master_gpio_match);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_new = fsi_master_gpio_remove,892};893 894module_platform_driver(fsi_master_gpio_driver);895MODULE_DESCRIPTION("A FSI master controller, using a simple GPIO bit-banging interface");896MODULE_LICENSE("GPL");897