drivers/platform/chrome/cros_ec_spi.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 // SPI interface for ChromeOS Embedded Controller
   3 //
   4 // Copyright (C) 2012 Google, Inc
   5
   6 #include <linux/delay.h>
   7 #include <linux/kernel.h>
   8 #include <linux/module.h>
   9 #include <linux/of.h>
  10 #include <linux/platform_data/cros_ec_commands.h>
  11 #include <linux/platform_data/cros_ec_proto.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/slab.h>
  14 #include <linux/spi/spi.h>
  15 #include <uapi/linux/sched/types.h>
  16
  17 #include "cros_ec.h"
  18
  19 /* The header byte, which follows the preamble */
  20 #define EC_MSG_HEADER                   0xec
  21
  22 /*
  23  * Number of EC preamble bytes we read at a time. Since it takes
  24  * about 400-500us for the EC to respond there is not a lot of
  25  * point in tuning this. If the EC could respond faster then
  26  * we could increase this so that might expect the preamble and
  27  * message to occur in a single transaction. However, the maximum
  28  * SPI transfer size is 256 bytes, so at 5MHz we need a response
  29  * time of perhaps <320us (200 bytes / 1600 bits).
  30  */
  31 #define EC_MSG_PREAMBLE_COUNT           32
  32
  33 /*
  34  * Allow for a long time for the EC to respond.  We support i2c
  35  * tunneling and support fairly long messages for the tunnel (249
  36  * bytes long at the moment).  If we're talking to a 100 kHz device
  37  * on the other end and need to transfer ~256 bytes, then we need:
  38  *  10 us/bit * ~10 bits/byte * ~256 bytes = ~25ms
  39  *
  40  * We'll wait 8 times that to handle clock stretching and other
  41  * paranoia.  Note that some battery gas gauge ICs claim to have a
  42  * clock stretch of 144ms in rare situations.  That's incentive for
  43  * not directly passing i2c through, but it's too late for that for
  44  * existing hardware.
  45  *
  46  * It's pretty unlikely that we'll really see a 249 byte tunnel in
  47  * anything other than testing.  If this was more common we might
  48  * consider having slow commands like this require a GET_STATUS
  49  * wait loop.  The 'flash write' command would be another candidate
  50  * for this, clocking in at 2-3ms.
  51  */
  52 #define EC_MSG_DEADLINE_MS              200
  53
  54 /*
  55   * Time between raising the SPI chip select (for the end of a
  56   * transaction) and dropping it again (for the next transaction).
  57   * If we go too fast, the EC will miss the transaction. We know that we
  58   * need at least 70 us with the 16 MHz STM32 EC, so go with 200 us to be
  59   * safe.
  60   */
  61 #define EC_SPI_RECOVERY_TIME_NS (200 * 1000)
  62
  63 /**
  64  * struct cros_ec_spi - information about a SPI-connected EC
  65  *
  66  * @spi: SPI device we are connected to
  67  * @last_transfer_ns: time that we last finished a transfer.
  68  * @start_of_msg_delay: used to set the delay_usecs on the spi_transfer that
  69  *      is sent when we want to turn on CS at the start of a transaction.
  70  * @end_of_msg_delay: used to set the delay_usecs on the spi_transfer that
  71  *      is sent when we want to turn off CS at the end of a transaction.
  72  * @high_pri_worker: Used to schedule high priority work.
  73  */
  74 struct cros_ec_spi {
  75         struct spi_device *spi;
  76         s64 last_transfer_ns;
  77         unsigned int start_of_msg_delay;
  78         unsigned int end_of_msg_delay;
  79         struct kthread_worker *high_pri_worker;
  80 };
  81
  82 typedef int (*cros_ec_xfer_fn_t) (struct cros_ec_device *ec_dev,
  83                                   struct cros_ec_command *ec_msg);
  84
  85 /**
  86  * struct cros_ec_xfer_work_params - params for our high priority workers
  87  *
  88  * @work: The work_struct needed to queue work
  89  * @fn: The function to use to transfer
  90  * @ec_dev: ChromeOS EC device
  91  * @ec_msg: Message to transfer
  92  * @ret: The return value of the function
  93  */
  94
  95 struct cros_ec_xfer_work_params {
  96         struct kthread_work work;
  97         cros_ec_xfer_fn_t fn;
  98         struct cros_ec_device *ec_dev;
  99         struct cros_ec_command *ec_msg;
 100         int ret;
 101 };
 102
 103 static void debug_packet(struct device *dev, const char *name, u8 *ptr,
 104                          int len)
 105 {
 106 #ifdef DEBUG
 107         int i;
 108
 109         dev_dbg(dev, "%s: ", name);
 110         for (i = 0; i < len; i++)
 111                 pr_cont(" %02x", ptr[i]);
 112
 113         pr_cont("\n");
 114 #endif
 115 }
 116
 117 static int terminate_request(struct cros_ec_device *ec_dev)
 118 {
 119         struct cros_ec_spi *ec_spi = ec_dev->priv;
 120         struct spi_message msg;
 121         struct spi_transfer trans;
 122         int ret;
 123
 124         /*
 125          * Turn off CS, possibly adding a delay to ensure the rising edge
 126          * doesn't come too soon after the end of the data.
 127          */
 128         spi_message_init(&msg);
 129         memset(&trans, 0, sizeof(trans));
 130         trans.delay.value = ec_spi->end_of_msg_delay;
 131         trans.delay.unit = SPI_DELAY_UNIT_USECS;
 132         spi_message_add_tail(&trans, &msg);
 133
 134         ret = spi_sync_locked(ec_spi->spi, &msg);
 135
 136         /* Reset end-of-response timer */
 137         ec_spi->last_transfer_ns = ktime_get_ns();
 138         if (ret < 0) {
 139                 dev_err(ec_dev->dev,
 140                         "cs-deassert spi transfer failed: %d\n",
 141                         ret);
 142         }
 143
 144         return ret;
 145 }
 146
 147 /**
 148  * receive_n_bytes - receive n bytes from the EC.
 149  *
 150  * Assumes buf is a pointer into the ec_dev->din buffer
 151  *
 152  * @ec_dev: ChromeOS EC device.
 153  * @buf: Pointer to the buffer receiving the data.
 154  * @n: Number of bytes received.
 155  */
 156 static int receive_n_bytes(struct cros_ec_device *ec_dev, u8 *buf, int n)
 157 {
 158         struct cros_ec_spi *ec_spi = ec_dev->priv;
 159         struct spi_transfer trans;
 160         struct spi_message msg;
 161         int ret;
 162
 163         BUG_ON(buf - ec_dev->din + n > ec_dev->din_size);
 164
 165         memset(&trans, 0, sizeof(trans));
 166         trans.cs_change = 1;
 167         trans.rx_buf = buf;
 168         trans.len = n;
 169
 170         spi_message_init(&msg);
 171         spi_message_add_tail(&trans, &msg);
 172         ret = spi_sync_locked(ec_spi->spi, &msg);
 173         if (ret < 0)
 174                 dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
 175
 176         return ret;
 177 }
 178
 179 /**
 180  * cros_ec_spi_receive_packet - Receive a packet from the EC.
 181  *
 182  * This function has two phases: reading the preamble bytes (since if we read
 183  * data from the EC before it is ready to send, we just get preamble) and
 184  * reading the actual message.
 185  *
 186  * The received data is placed into ec_dev->din.
 187  *
 188  * @ec_dev: ChromeOS EC device
 189  * @need_len: Number of message bytes we need to read
 190  */
 191 static int cros_ec_spi_receive_packet(struct cros_ec_device *ec_dev,
 192                                       int need_len)
 193 {
 194         struct ec_host_response *response;
 195         u8 *ptr, *end;
 196         int ret;
 197         unsigned long deadline;
 198         int todo;
 199
 200         BUG_ON(ec_dev->din_size < EC_MSG_PREAMBLE_COUNT);
 201
 202         /* Receive data until we see the header byte */
 203         deadline = jiffies + msecs_to_jiffies(EC_MSG_DEADLINE_MS);
 204         while (true) {
 205                 unsigned long start_jiffies = jiffies;
 206
 207                 ret = receive_n_bytes(ec_dev,
 208                                       ec_dev->din,
 209                                       EC_MSG_PREAMBLE_COUNT);
 210                 if (ret < 0)
 211                         return ret;
 212
 213                 ptr = ec_dev->din;
 214                 for (end = ptr + EC_MSG_PREAMBLE_COUNT; ptr != end; ptr++) {
 215                         if (*ptr == EC_SPI_FRAME_START) {
 216                                 dev_dbg(ec_dev->dev, "msg found at %zd\n",
 217                                         ptr - ec_dev->din);
 218                                 break;
 219                         }
 220                 }
 221                 if (ptr != end)
 222                         break;
 223
 224                 /*
 225                  * Use the time at the start of the loop as a timeout.  This
 226                  * gives us one last shot at getting the transfer and is useful
 227                  * in case we got context switched out for a while.
 228                  */
 229                 if (time_after(start_jiffies, deadline)) {
 230                         dev_warn(ec_dev->dev, "EC failed to respond in time\n");
 231                         return -ETIMEDOUT;
 232                 }
 233         }
 234
 235         /*
 236          * ptr now points to the header byte. Copy any valid data to the
 237          * start of our buffer
 238          */
 239         todo = end - ++ptr;
 240         BUG_ON(todo < 0 || todo > ec_dev->din_size);
 241         todo = min(todo, need_len);
 242         memmove(ec_dev->din, ptr, todo);
 243         ptr = ec_dev->din + todo;
 244         dev_dbg(ec_dev->dev, "need %d, got %d bytes from preamble\n",
 245                 need_len, todo);
 246         need_len -= todo;
 247
 248         /* If the entire response struct wasn't read, get the rest of it. */
 249         if (todo < sizeof(*response)) {
 250                 ret = receive_n_bytes(ec_dev, ptr, sizeof(*response) - todo);
 251                 if (ret < 0)
 252                         return -EBADMSG;
 253                 ptr += (sizeof(*response) - todo);
 254                 todo = sizeof(*response);
 255         }
 256
 257         response = (struct ec_host_response *)ec_dev->din;
 258
 259         /* Abort if data_len is too large. */
 260         if (response->data_len > ec_dev->din_size)
 261                 return -EMSGSIZE;
 262
 263         /* Receive data until we have it all */
 264         while (need_len > 0) {
 265                 /*
 266                  * We can't support transfers larger than the SPI FIFO size
 267                  * unless we have DMA. We don't have DMA on the ISP SPI ports
 268                  * for Exynos. We need a way of asking SPI driver for
 269                  * maximum-supported transfer size.
 270                  */
 271                 todo = min(need_len, 256);
 272                 dev_dbg(ec_dev->dev, "loop, todo=%d, need_len=%d, ptr=%zd\n",
 273                         todo, need_len, ptr - ec_dev->din);
 274
 275                 ret = receive_n_bytes(ec_dev, ptr, todo);
 276                 if (ret < 0)
 277                         return ret;
 278
 279                 ptr += todo;
 280                 need_len -= todo;
 281         }
 282
 283         dev_dbg(ec_dev->dev, "loop done, ptr=%zd\n", ptr - ec_dev->din);
 284
 285         return 0;
 286 }
 287
 288 /**
 289  * cros_ec_spi_receive_response - Receive a response from the EC.
 290  *
 291  * This function has two phases: reading the preamble bytes (since if we read
 292  * data from the EC before it is ready to send, we just get preamble) and
 293  * reading the actual message.
 294  *
 295  * The received data is placed into ec_dev->din.
 296  *
 297  * @ec_dev: ChromeOS EC device
 298  * @need_len: Number of message bytes we need to read
 299  */
 300 static int cros_ec_spi_receive_response(struct cros_ec_device *ec_dev,
 301                                         int need_len)
 302 {
 303         u8 *ptr, *end;
 304         int ret;
 305         unsigned long deadline;
 306         int todo;
 307
 308         BUG_ON(ec_dev->din_size < EC_MSG_PREAMBLE_COUNT);
 309
 310         /* Receive data until we see the header byte */
 311         deadline = jiffies + msecs_to_jiffies(EC_MSG_DEADLINE_MS);
 312         while (true) {
 313                 unsigned long start_jiffies = jiffies;
 314
 315                 ret = receive_n_bytes(ec_dev,
 316                                       ec_dev->din,
 317                                       EC_MSG_PREAMBLE_COUNT);
 318                 if (ret < 0)
 319                         return ret;
 320
 321                 ptr = ec_dev->din;
 322                 for (end = ptr + EC_MSG_PREAMBLE_COUNT; ptr != end; ptr++) {
 323                         if (*ptr == EC_SPI_FRAME_START) {
 324                                 dev_dbg(ec_dev->dev, "msg found at %zd\n",
 325                                         ptr - ec_dev->din);
 326                                 break;
 327                         }
 328                 }
 329                 if (ptr != end)
 330                         break;
 331
 332                 /*
 333                  * Use the time at the start of the loop as a timeout.  This
 334                  * gives us one last shot at getting the transfer and is useful
 335                  * in case we got context switched out for a while.
 336                  */
 337                 if (time_after(start_jiffies, deadline)) {
 338                         dev_warn(ec_dev->dev, "EC failed to respond in time\n");
 339                         return -ETIMEDOUT;
 340                 }
 341         }
 342
 343         /*
 344          * ptr now points to the header byte. Copy any valid data to the
 345          * start of our buffer
 346          */
 347         todo = end - ++ptr;
 348         BUG_ON(todo < 0 || todo > ec_dev->din_size);
 349         todo = min(todo, need_len);
 350         memmove(ec_dev->din, ptr, todo);
 351         ptr = ec_dev->din + todo;
 352         dev_dbg(ec_dev->dev, "need %d, got %d bytes from preamble\n",
 353                  need_len, todo);
 354         need_len -= todo;
 355
 356         /* Receive data until we have it all */
 357         while (need_len > 0) {
 358                 /*
 359                  * We can't support transfers larger than the SPI FIFO size
 360                  * unless we have DMA. We don't have DMA on the ISP SPI ports
 361                  * for Exynos. We need a way of asking SPI driver for
 362                  * maximum-supported transfer size.
 363                  */
 364                 todo = min(need_len, 256);
 365                 dev_dbg(ec_dev->dev, "loop, todo=%d, need_len=%d, ptr=%zd\n",
 366                         todo, need_len, ptr - ec_dev->din);
 367
 368                 ret = receive_n_bytes(ec_dev, ptr, todo);
 369                 if (ret < 0)
 370                         return ret;
 371
 372                 debug_packet(ec_dev->dev, "interim", ptr, todo);
 373                 ptr += todo;
 374                 need_len -= todo;
 375         }
 376
 377         dev_dbg(ec_dev->dev, "loop done, ptr=%zd\n", ptr - ec_dev->din);
 378
 379         return 0;
 380 }
 381
 382 /**
 383  * do_cros_ec_pkt_xfer_spi - Transfer a packet over SPI and receive the reply
 384  *
 385  * @ec_dev: ChromeOS EC device
 386  * @ec_msg: Message to transfer
 387  */
 388 static int do_cros_ec_pkt_xfer_spi(struct cros_ec_device *ec_dev,
 389                                    struct cros_ec_command *ec_msg)
 390 {
 391         struct ec_host_response *response;
 392         struct cros_ec_spi *ec_spi = ec_dev->priv;
 393         struct spi_transfer trans, trans_delay;
 394         struct spi_message msg;
 395         int i, len;
 396         u8 *ptr;
 397         u8 *rx_buf;
 398         u8 sum;
 399         u8 rx_byte;
 400         int ret = 0, final_ret;
 401         unsigned long delay;
 402
 403         len = cros_ec_prepare_tx(ec_dev, ec_msg);
 404         dev_dbg(ec_dev->dev, "prepared, len=%d\n", len);
 405
 406         /* If it's too soon to do another transaction, wait */
 407         delay = ktime_get_ns() - ec_spi->last_transfer_ns;
 408         if (delay < EC_SPI_RECOVERY_TIME_NS)
 409                 ndelay(EC_SPI_RECOVERY_TIME_NS - delay);
 410
 411         rx_buf = kzalloc(len, GFP_KERNEL);
 412         if (!rx_buf)
 413                 return -ENOMEM;
 414
 415         spi_bus_lock(ec_spi->spi->master);
 416
 417         /*
 418          * Leave a gap between CS assertion and clocking of data to allow the
 419          * EC time to wakeup.
 420          */
 421         spi_message_init(&msg);
 422         if (ec_spi->start_of_msg_delay) {
 423                 memset(&trans_delay, 0, sizeof(trans_delay));
 424                 trans_delay.delay.value = ec_spi->start_of_msg_delay;
 425                 trans_delay.delay.unit = SPI_DELAY_UNIT_USECS;
 426                 spi_message_add_tail(&trans_delay, &msg);
 427         }
 428
 429         /* Transmit phase - send our message */
 430         memset(&trans, 0, sizeof(trans));
 431         trans.tx_buf = ec_dev->dout;
 432         trans.rx_buf = rx_buf;
 433         trans.len = len;
 434         trans.cs_change = 1;
 435         spi_message_add_tail(&trans, &msg);
 436         ret = spi_sync_locked(ec_spi->spi, &msg);
 437
 438         /* Get the response */
 439         if (!ret) {
 440                 /* Verify that EC can process command */
 441                 for (i = 0; i < len; i++) {
 442                         rx_byte = rx_buf[i];
 443                         /*
 444                          * Seeing the PAST_END, RX_BAD_DATA, or NOT_READY
 445                          * markers are all signs that the EC didn't fully
 446                          * receive our command. e.g., if the EC is flashing
 447                          * itself, it can't respond to any commands and instead
 448                          * clocks out EC_SPI_PAST_END from its SPI hardware
 449                          * buffer. Similar occurrences can happen if the AP is
 450                          * too slow to clock out data after asserting CS -- the
 451                          * EC will abort and fill its buffer with
 452                          * EC_SPI_RX_BAD_DATA.
 453                          *
 454                          * In all cases, these errors should be safe to retry.
 455                          * Report -EAGAIN and let the caller decide what to do
 456                          * about that.
 457                          */
 458                         if (rx_byte == EC_SPI_PAST_END  ||
 459                             rx_byte == EC_SPI_RX_BAD_DATA ||
 460                             rx_byte == EC_SPI_NOT_READY) {
 461                                 ret = -EAGAIN;
 462                                 break;
 463                         }
 464                 }
 465         }
 466
 467         if (!ret)
 468                 ret = cros_ec_spi_receive_packet(ec_dev,
 469                                 ec_msg->insize + sizeof(*response));
 470         else if (ret != -EAGAIN)
 471                 dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
 472
 473         final_ret = terminate_request(ec_dev);
 474
 475         spi_bus_unlock(ec_spi->spi->master);
 476
 477         if (!ret)
 478                 ret = final_ret;
 479         if (ret < 0)
 480                 goto exit;
 481
 482         ptr = ec_dev->din;
 483
 484         /* check response error code */
 485         response = (struct ec_host_response *)ptr;
 486         ec_msg->result = response->result;
 487
 488         ret = cros_ec_check_result(ec_dev, ec_msg);
 489         if (ret)
 490                 goto exit;
 491
 492         len = response->data_len;
 493         sum = 0;
 494         if (len > ec_msg->insize) {
 495                 dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
 496                         len, ec_msg->insize);
 497                 ret = -EMSGSIZE;
 498                 goto exit;
 499         }
 500
 501         for (i = 0; i < sizeof(*response); i++)
 502                 sum += ptr[i];
 503
 504         /* copy response packet payload and compute checksum */
 505         memcpy(ec_msg->data, ptr + sizeof(*response), len);
 506         for (i = 0; i < len; i++)
 507                 sum += ec_msg->data[i];
 508
 509         if (sum) {
 510                 dev_err(ec_dev->dev,
 511                         "bad packet checksum, calculated %x\n",
 512                         sum);
 513                 ret = -EBADMSG;
 514                 goto exit;
 515         }
 516
 517         ret = len;
 518 exit:
 519         kfree(rx_buf);
 520         if (ec_msg->command == EC_CMD_REBOOT_EC)
 521                 msleep(EC_REBOOT_DELAY_MS);
 522
 523         return ret;
 524 }
 525
 526 /**
 527  * do_cros_ec_cmd_xfer_spi - Transfer a message over SPI and receive the reply
 528  *
 529  * @ec_dev: ChromeOS EC device
 530  * @ec_msg: Message to transfer
 531  */
 532 static int do_cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev,
 533                                    struct cros_ec_command *ec_msg)
 534 {
 535         struct cros_ec_spi *ec_spi = ec_dev->priv;
 536         struct spi_transfer trans;
 537         struct spi_message msg;
 538         int i, len;
 539         u8 *ptr;
 540         u8 *rx_buf;
 541         u8 rx_byte;
 542         int sum;
 543         int ret = 0, final_ret;
 544         unsigned long delay;
 545
 546         len = cros_ec_prepare_tx(ec_dev, ec_msg);
 547         dev_dbg(ec_dev->dev, "prepared, len=%d\n", len);
 548
 549         /* If it's too soon to do another transaction, wait */
 550         delay = ktime_get_ns() - ec_spi->last_transfer_ns;
 551         if (delay < EC_SPI_RECOVERY_TIME_NS)
 552                 ndelay(EC_SPI_RECOVERY_TIME_NS - delay);
 553
 554         rx_buf = kzalloc(len, GFP_KERNEL);
 555         if (!rx_buf)
 556                 return -ENOMEM;
 557
 558         spi_bus_lock(ec_spi->spi->master);
 559
 560         /* Transmit phase - send our message */
 561         debug_packet(ec_dev->dev, "out", ec_dev->dout, len);
 562         memset(&trans, 0, sizeof(trans));
 563         trans.tx_buf = ec_dev->dout;
 564         trans.rx_buf = rx_buf;
 565         trans.len = len;
 566         trans.cs_change = 1;
 567         spi_message_init(&msg);
 568         spi_message_add_tail(&trans, &msg);
 569         ret = spi_sync_locked(ec_spi->spi, &msg);
 570
 571         /* Get the response */
 572         if (!ret) {
 573                 /* Verify that EC can process command */
 574                 for (i = 0; i < len; i++) {
 575                         rx_byte = rx_buf[i];
 576                         /* See comments in cros_ec_pkt_xfer_spi() */
 577                         if (rx_byte == EC_SPI_PAST_END  ||
 578                             rx_byte == EC_SPI_RX_BAD_DATA ||
 579                             rx_byte == EC_SPI_NOT_READY) {
 580                                 ret = -EAGAIN;
 581                                 break;
 582                         }
 583                 }
 584         }
 585
 586         if (!ret)
 587                 ret = cros_ec_spi_receive_response(ec_dev,
 588                                 ec_msg->insize + EC_MSG_TX_PROTO_BYTES);
 589         else if (ret != -EAGAIN)
 590                 dev_err(ec_dev->dev, "spi transfer failed: %d\n", ret);
 591
 592         final_ret = terminate_request(ec_dev);
 593
 594         spi_bus_unlock(ec_spi->spi->master);
 595
 596         if (!ret)
 597                 ret = final_ret;
 598         if (ret < 0)
 599                 goto exit;
 600
 601         ptr = ec_dev->din;
 602
 603         /* check response error code */
 604         ec_msg->result = ptr[0];
 605         ret = cros_ec_check_result(ec_dev, ec_msg);
 606         if (ret)
 607                 goto exit;
 608
 609         len = ptr[1];
 610         sum = ptr[0] + ptr[1];
 611         if (len > ec_msg->insize) {
 612                 dev_err(ec_dev->dev, "packet too long (%d bytes, expected %d)",
 613                         len, ec_msg->insize);
 614                 ret = -ENOSPC;
 615                 goto exit;
 616         }
 617
 618         /* copy response packet payload and compute checksum */
 619         for (i = 0; i < len; i++) {
 620                 sum += ptr[i + 2];
 621                 if (ec_msg->insize)
 622                         ec_msg->data[i] = ptr[i + 2];
 623         }
 624         sum &= 0xff;
 625
 626         debug_packet(ec_dev->dev, "in", ptr, len + 3);
 627
 628         if (sum != ptr[len + 2]) {
 629                 dev_err(ec_dev->dev,
 630                         "bad packet checksum, expected %02x, got %02x\n",
 631                         sum, ptr[len + 2]);
 632                 ret = -EBADMSG;
 633                 goto exit;
 634         }
 635
 636         ret = len;
 637 exit:
 638         kfree(rx_buf);
 639         if (ec_msg->command == EC_CMD_REBOOT_EC)
 640                 msleep(EC_REBOOT_DELAY_MS);
 641
 642         return ret;
 643 }
 644
 645 static void cros_ec_xfer_high_pri_work(struct kthread_work *work)
 646 {
 647         struct cros_ec_xfer_work_params *params;
 648
 649         params = container_of(work, struct cros_ec_xfer_work_params, work);
 650         params->ret = params->fn(params->ec_dev, params->ec_msg);
 651 }
 652
 653 static int cros_ec_xfer_high_pri(struct cros_ec_device *ec_dev,
 654                                  struct cros_ec_command *ec_msg,
 655                                  cros_ec_xfer_fn_t fn)
 656 {
 657         struct cros_ec_spi *ec_spi = ec_dev->priv;
 658         struct cros_ec_xfer_work_params params = {
 659                 .work = KTHREAD_WORK_INIT(params.work,
 660                                           cros_ec_xfer_high_pri_work),
 661                 .ec_dev = ec_dev,
 662                 .ec_msg = ec_msg,
 663                 .fn = fn,
 664         };
 665
 666         /*
 667          * This looks a bit ridiculous.  Why do the work on a
 668          * different thread if we're just going to block waiting for
 669          * the thread to finish?  The key here is that the thread is
 670          * running at high priority but the calling context might not
 671          * be.  We need to be at high priority to avoid getting
 672          * context switched out for too long and the EC giving up on
 673          * the transfer.
 674          */
 675         kthread_queue_work(ec_spi->high_pri_worker, &params.work);
 676         kthread_flush_work(&params.work);
 677
 678         return params.ret;
 679 }
 680
 681 static int cros_ec_pkt_xfer_spi(struct cros_ec_device *ec_dev,
 682                                 struct cros_ec_command *ec_msg)
 683 {
 684         return cros_ec_xfer_high_pri(ec_dev, ec_msg, do_cros_ec_pkt_xfer_spi);
 685 }
 686
 687 static int cros_ec_cmd_xfer_spi(struct cros_ec_device *ec_dev,
 688                                 struct cros_ec_command *ec_msg)
 689 {
 690         return cros_ec_xfer_high_pri(ec_dev, ec_msg, do_cros_ec_cmd_xfer_spi);
 691 }
 692
 693 static void cros_ec_spi_dt_probe(struct cros_ec_spi *ec_spi, struct device *dev)
 694 {
 695         struct device_node *np = dev->of_node;
 696         u32 val;
 697         int ret;
 698
 699         ret = of_property_read_u32(np, "google,cros-ec-spi-pre-delay", &val);
 700         if (!ret)
 701                 ec_spi->start_of_msg_delay = val;
 702
 703         ret = of_property_read_u32(np, "google,cros-ec-spi-msg-delay", &val);
 704         if (!ret)
 705                 ec_spi->end_of_msg_delay = val;
 706 }
 707
 708 static void cros_ec_spi_high_pri_release(void *worker)
 709 {
 710         kthread_destroy_worker(worker);
 711 }
 712
 713 static int cros_ec_spi_devm_high_pri_alloc(struct device *dev,
 714                                            struct cros_ec_spi *ec_spi)
 715 {
 716         int err;
 717
 718         ec_spi->high_pri_worker =
 719                 kthread_create_worker(0, "cros_ec_spi_high_pri");
 720
 721         if (IS_ERR(ec_spi->high_pri_worker)) {
 722                 err = PTR_ERR(ec_spi->high_pri_worker);
 723                 dev_err(dev, "Can't create cros_ec high pri worker: %d\n", err);
 724                 return err;
 725         }
 726
 727         err = devm_add_action_or_reset(dev, cros_ec_spi_high_pri_release,
 728                                        ec_spi->high_pri_worker);
 729         if (err)
 730                 return err;
 731
 732         sched_set_fifo(ec_spi->high_pri_worker->task);
 733
 734         return 0;
 735 }
 736
 737 static int cros_ec_spi_probe(struct spi_device *spi)
 738 {
 739         struct device *dev = &spi->dev;
 740         struct cros_ec_device *ec_dev;
 741         struct cros_ec_spi *ec_spi;
 742         int err;
 743
 744         spi->rt = true;
 745         err = spi_setup(spi);
 746         if (err < 0)
 747                 return err;
 748
 749         ec_spi = devm_kzalloc(dev, sizeof(*ec_spi), GFP_KERNEL);
 750         if (ec_spi == NULL)
 751                 return -ENOMEM;
 752         ec_spi->spi = spi;
 753         ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
 754         if (!ec_dev)
 755                 return -ENOMEM;
 756
 757         /* Check for any DT properties */
 758         cros_ec_spi_dt_probe(ec_spi, dev);
 759
 760         spi_set_drvdata(spi, ec_dev);
 761         ec_dev->dev = dev;
 762         ec_dev->priv = ec_spi;
 763         ec_dev->irq = spi->irq;
 764         ec_dev->cmd_xfer = cros_ec_cmd_xfer_spi;
 765         ec_dev->pkt_xfer = cros_ec_pkt_xfer_spi;
 766         ec_dev->phys_name = dev_name(&ec_spi->spi->dev);
 767         ec_dev->din_size = EC_MSG_PREAMBLE_COUNT +
 768                            sizeof(struct ec_host_response) +
 769                            sizeof(struct ec_response_get_protocol_info);
 770         ec_dev->dout_size = sizeof(struct ec_host_request);
 771
 772         ec_spi->last_transfer_ns = ktime_get_ns();
 773
 774         err = cros_ec_spi_devm_high_pri_alloc(dev, ec_spi);
 775         if (err)
 776                 return err;
 777
 778         err = cros_ec_register(ec_dev);
 779         if (err) {
 780                 dev_err(dev, "cannot register EC\n");
 781                 return err;
 782         }
 783
 784         device_init_wakeup(&spi->dev, true);
 785
 786         return 0;
 787 }
 788
 789 static int cros_ec_spi_remove(struct spi_device *spi)
 790 {
 791         struct cros_ec_device *ec_dev = spi_get_drvdata(spi);
 792
 793         return cros_ec_unregister(ec_dev);
 794 }
 795
 796 #ifdef CONFIG_PM_SLEEP
 797 static int cros_ec_spi_suspend(struct device *dev)
 798 {
 799         struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
 800
 801         return cros_ec_suspend(ec_dev);
 802 }
 803
 804 static int cros_ec_spi_resume(struct device *dev)
 805 {
 806         struct cros_ec_device *ec_dev = dev_get_drvdata(dev);
 807
 808         return cros_ec_resume(ec_dev);
 809 }
 810 #endif
 811
 812 static SIMPLE_DEV_PM_OPS(cros_ec_spi_pm_ops, cros_ec_spi_suspend,
 813                          cros_ec_spi_resume);
 814
 815 static const struct of_device_id cros_ec_spi_of_match[] = {
 816         { .compatible = "google,cros-ec-spi", },
 817         { /* sentinel */ },
 818 };
 819 MODULE_DEVICE_TABLE(of, cros_ec_spi_of_match);
 820
 821 static const struct spi_device_id cros_ec_spi_id[] = {
 822         { "cros-ec-spi", 0 },
 823         { }
 824 };
 825 MODULE_DEVICE_TABLE(spi, cros_ec_spi_id);
 826
 827 static struct spi_driver cros_ec_driver_spi = {
 828         .driver = {
 829                 .name   = "cros-ec-spi",
 830                 .of_match_table = cros_ec_spi_of_match,
 831                 .pm     = &cros_ec_spi_pm_ops,
 832         },
 833         .probe          = cros_ec_spi_probe,
 834         .remove         = cros_ec_spi_remove,
 835         .id_table       = cros_ec_spi_id,
 836 };
 837
 838 module_spi_driver(cros_ec_driver_spi);
 839
 840 MODULE_LICENSE("GPL v2");
 841 MODULE_DESCRIPTION("SPI interface for ChromeOS Embedded Controller");