drivers/acpi/ec.c

   1 /*
   2  *  ec.c - ACPI Embedded Controller Driver (v3)
   3  *
   4  *  Copyright (C) 2001-2015 Intel Corporation
   5  *    Author: 2014, 2015 Lv Zheng <lv.zheng@intel.com>
   6  *            2006, 2007 Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
   7  *            2006       Denis Sadykov <denis.m.sadykov@intel.com>
   8  *            2004       Luming Yu <luming.yu@intel.com>
   9  *            2001, 2002 Andy Grover <andrew.grover@intel.com>
  10  *            2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
  11  *  Copyright (C) 2008      Alexey Starikovskiy <astarikovskiy@suse.de>
  12  *
  13  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  14  *
  15  *  This program is free software; you can redistribute it and/or modify
  16  *  it under the terms of the GNU General Public License as published by
  17  *  the Free Software Foundation; either version 2 of the License, or (at
  18  *  your option) any later version.
  19  *
  20  *  This program is distributed in the hope that it will be useful, but
  21  *  WITHOUT ANY WARRANTY; without even the implied warranty of
  22  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  23  *  General Public License for more details.
  24  *
  25  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  26  */
  27
  28 /* Uncomment next line to get verbose printout */
  29 /* #define DEBUG */
  30 #define pr_fmt(fmt) "ACPI : EC: " fmt
  31
  32 #include <linux/kernel.h>
  33 #include <linux/module.h>
  34 #include <linux/init.h>
  35 #include <linux/types.h>
  36 #include <linux/delay.h>
  37 #include <linux/interrupt.h>
  38 #include <linux/list.h>
  39 #include <linux/spinlock.h>
  40 #include <linux/slab.h>
  41 #include <linux/acpi.h>
  42 #include <linux/dmi.h>
  43 #include <asm/io.h>
  44
  45 #include "internal.h"
  46
  47 #define ACPI_EC_CLASS                   "embedded_controller"
  48 #define ACPI_EC_DEVICE_NAME             "Embedded Controller"
  49 #define ACPI_EC_FILE_INFO               "info"
  50
  51 /* EC status register */
  52 #define ACPI_EC_FLAG_OBF        0x01    /* Output buffer full */
  53 #define ACPI_EC_FLAG_IBF        0x02    /* Input buffer full */
  54 #define ACPI_EC_FLAG_CMD        0x08    /* Input buffer contains a command */
  55 #define ACPI_EC_FLAG_BURST      0x10    /* burst mode */
  56 #define ACPI_EC_FLAG_SCI        0x20    /* EC-SCI occurred */
  57
  58 /*
  59  * The SCI_EVT clearing timing is not defined by the ACPI specification.
  60  * This leads to lots of practical timing issues for the host EC driver.
  61  * The following variations are defined (from the target EC firmware's
  62  * perspective):
  63  * STATUS: After indicating SCI_EVT edge triggered IRQ to the host, the
  64  *         target can clear SCI_EVT at any time so long as the host can see
  65  *         the indication by reading the status register (EC_SC). So the
  66  *         host should re-check SCI_EVT after the first time the SCI_EVT
  67  *         indication is seen, which is the same time the query request
  68  *         (QR_EC) is written to the command register (EC_CMD). SCI_EVT set
  69  *         at any later time could indicate another event. Normally such
  70  *         kind of EC firmware has implemented an event queue and will
  71  *         return 0x00 to indicate "no outstanding event".
  72  * QUERY: After seeing the query request (QR_EC) written to the command
  73  *        register (EC_CMD) by the host and having prepared the responding
  74  *        event value in the data register (EC_DATA), the target can safely
  75  *        clear SCI_EVT because the target can confirm that the current
  76  *        event is being handled by the host. The host then should check
  77  *        SCI_EVT right after reading the event response from the data
  78  *        register (EC_DATA).
  79  * EVENT: After seeing the event response read from the data register
  80  *        (EC_DATA) by the host, the target can clear SCI_EVT. As the
  81  *        target requires time to notice the change in the data register
  82  *        (EC_DATA), the host may be required to wait additional guarding
  83  *        time before checking the SCI_EVT again. Such guarding may not be
  84  *        necessary if the host is notified via another IRQ.
  85  */
  86 #define ACPI_EC_EVT_TIMING_STATUS       0x00
  87 #define ACPI_EC_EVT_TIMING_QUERY        0x01
  88 #define ACPI_EC_EVT_TIMING_EVENT        0x02
  89
  90 /* EC commands */
  91 enum ec_command {
  92         ACPI_EC_COMMAND_READ = 0x80,
  93         ACPI_EC_COMMAND_WRITE = 0x81,
  94         ACPI_EC_BURST_ENABLE = 0x82,
  95         ACPI_EC_BURST_DISABLE = 0x83,
  96         ACPI_EC_COMMAND_QUERY = 0x84,
  97 };
  98
  99 #define ACPI_EC_DELAY           500     /* Wait 500ms max. during EC ops */
 100 #define ACPI_EC_UDELAY_GLK      1000    /* Wait 1ms max. to get global lock */
 101 #define ACPI_EC_UDELAY_POLL     550     /* Wait 1ms for EC transaction polling */
 102 #define ACPI_EC_CLEAR_MAX       100     /* Maximum number of events to query
 103                                          * when trying to clear the EC */
 104 #define ACPI_EC_MAX_QUERIES     16      /* Maximum number of parallel queries */
 105
 106 enum {
 107         EC_FLAGS_QUERY_ENABLED,         /* Query is enabled */
 108         EC_FLAGS_QUERY_PENDING,         /* Query is pending */
 109         EC_FLAGS_QUERY_GUARDING,        /* Guard for SCI_EVT check */
 110         EC_FLAGS_GPE_HANDLER_INSTALLED, /* GPE handler installed */
 111         EC_FLAGS_EC_HANDLER_INSTALLED,  /* OpReg handler installed */
 112         EC_FLAGS_STARTED,               /* Driver is started */
 113         EC_FLAGS_STOPPED,               /* Driver is stopped */
 114         EC_FLAGS_COMMAND_STORM,         /* GPE storms occurred to the
 115                                          * current command processing */
 116 };
 117
 118 #define ACPI_EC_COMMAND_POLL            0x01 /* Available for command byte */
 119 #define ACPI_EC_COMMAND_COMPLETE        0x02 /* Completed last byte */
 120
 121 /* ec.c is compiled in acpi namespace so this shows up as acpi.ec_delay param */
 122 static unsigned int ec_delay __read_mostly = ACPI_EC_DELAY;
 123 module_param(ec_delay, uint, 0644);
 124 MODULE_PARM_DESC(ec_delay, "Timeout(ms) waited until an EC command completes");
 125
 126 static unsigned int ec_max_queries __read_mostly = ACPI_EC_MAX_QUERIES;
 127 module_param(ec_max_queries, uint, 0644);
 128 MODULE_PARM_DESC(ec_max_queries, "Maximum parallel _Qxx evaluations");
 129
 130 static bool ec_busy_polling __read_mostly;
 131 module_param(ec_busy_polling, bool, 0644);
 132 MODULE_PARM_DESC(ec_busy_polling, "Use busy polling to advance EC transaction");
 133
 134 static unsigned int ec_polling_guard __read_mostly = ACPI_EC_UDELAY_POLL;
 135 module_param(ec_polling_guard, uint, 0644);
 136 MODULE_PARM_DESC(ec_polling_guard, "Guard time(us) between EC accesses in polling modes");
 137
 138 static unsigned int ec_event_clearing __read_mostly = ACPI_EC_EVT_TIMING_QUERY;
 139
 140 /*
 141  * If the number of false interrupts per one transaction exceeds
 142  * this threshold, will think there is a GPE storm happened and
 143  * will disable the GPE for normal transaction.
 144  */
 145 static unsigned int ec_storm_threshold  __read_mostly = 8;
 146 module_param(ec_storm_threshold, uint, 0644);
 147 MODULE_PARM_DESC(ec_storm_threshold, "Maxim false GPE numbers not considered as GPE storm");
 148
 149 static bool ec_freeze_events __read_mostly = true;
 150 module_param(ec_freeze_events, bool, 0644);
 151 MODULE_PARM_DESC(ec_freeze_events, "Disabling event handling during suspend/resume");
 152
 153 struct acpi_ec_query_handler {
 154         struct list_head node;
 155         acpi_ec_query_func func;
 156         acpi_handle handle;
 157         void *data;
 158         u8 query_bit;
 159         struct kref kref;
 160 };
 161
 162 struct transaction {
 163         const u8 *wdata;
 164         u8 *rdata;
 165         unsigned short irq_count;
 166         u8 command;
 167         u8 wi;
 168         u8 ri;
 169         u8 wlen;
 170         u8 rlen;
 171         u8 flags;
 172 };
 173
 174 struct acpi_ec_query {
 175         struct transaction transaction;
 176         struct work_struct work;
 177         struct acpi_ec_query_handler *handler;
 178 };
 179
 180 static int acpi_ec_query(struct acpi_ec *ec, u8 *data);
 181 static void advance_transaction(struct acpi_ec *ec);
 182 static void acpi_ec_event_handler(struct work_struct *work);
 183 static void acpi_ec_event_processor(struct work_struct *work);
 184
 185 struct acpi_ec *boot_ec, *first_ec;
 186 EXPORT_SYMBOL(first_ec);
 187 static struct workqueue_struct *ec_query_wq;
 188
 189 static int EC_FLAGS_CLEAR_ON_RESUME; /* Needs acpi_ec_clear() on boot/resume */
 190 static int EC_FLAGS_QUERY_HANDSHAKE; /* Needs QR_EC issued when SCI_EVT set */
 191 static int EC_FLAGS_CORRECT_ECDT; /* Needs ECDT port address correction */
 192
 193 /* --------------------------------------------------------------------------
 194  *                           Logging/Debugging
 195  * -------------------------------------------------------------------------- */
 196
 197 /*
 198  * Splitters used by the developers to track the boundary of the EC
 199  * handling processes.
 200  */
 201 #ifdef DEBUG
 202 #define EC_DBG_SEP      " "
 203 #define EC_DBG_DRV      "+++++"
 204 #define EC_DBG_STM      "====="
 205 #define EC_DBG_REQ      "*****"
 206 #define EC_DBG_EVT      "#####"
 207 #else
 208 #define EC_DBG_SEP      ""
 209 #define EC_DBG_DRV
 210 #define EC_DBG_STM
 211 #define EC_DBG_REQ
 212 #define EC_DBG_EVT
 213 #endif
 214
 215 #define ec_log_raw(fmt, ...) \
 216         pr_info(fmt "\n", ##__VA_ARGS__)
 217 #define ec_dbg_raw(fmt, ...) \
 218         pr_debug(fmt "\n", ##__VA_ARGS__)
 219 #define ec_log(filter, fmt, ...) \
 220         ec_log_raw(filter EC_DBG_SEP fmt EC_DBG_SEP filter, ##__VA_ARGS__)
 221 #define ec_dbg(filter, fmt, ...) \
 222         ec_dbg_raw(filter EC_DBG_SEP fmt EC_DBG_SEP filter, ##__VA_ARGS__)
 223
 224 #define ec_log_drv(fmt, ...) \
 225         ec_log(EC_DBG_DRV, fmt, ##__VA_ARGS__)
 226 #define ec_dbg_drv(fmt, ...) \
 227         ec_dbg(EC_DBG_DRV, fmt, ##__VA_ARGS__)
 228 #define ec_dbg_stm(fmt, ...) \
 229         ec_dbg(EC_DBG_STM, fmt, ##__VA_ARGS__)
 230 #define ec_dbg_req(fmt, ...) \
 231         ec_dbg(EC_DBG_REQ, fmt, ##__VA_ARGS__)
 232 #define ec_dbg_evt(fmt, ...) \
 233         ec_dbg(EC_DBG_EVT, fmt, ##__VA_ARGS__)
 234 #define ec_dbg_ref(ec, fmt, ...) \
 235         ec_dbg_raw("%lu: " fmt, ec->reference_count, ## __VA_ARGS__)
 236
 237 /* --------------------------------------------------------------------------
 238  *                           Device Flags
 239  * -------------------------------------------------------------------------- */
 240
 241 static bool acpi_ec_started(struct acpi_ec *ec)
 242 {
 243         return test_bit(EC_FLAGS_STARTED, &ec->flags) &&
 244                !test_bit(EC_FLAGS_STOPPED, &ec->flags);
 245 }
 246
 247 static bool acpi_ec_event_enabled(struct acpi_ec *ec)
 248 {
 249         /*
 250          * There is an OSPM early stage logic. During the early stages
 251          * (boot/resume), OSPMs shouldn't enable the event handling, only
 252          * the EC transactions are allowed to be performed.
 253          */
 254         if (!test_bit(EC_FLAGS_QUERY_ENABLED, &ec->flags))
 255                 return false;
 256         /*
 257          * However, disabling the event handling is experimental for late
 258          * stage (suspend), and is controlled by the boot parameter of
 259          * "ec_freeze_events":
 260          * 1. true:  The EC event handling is disabled before entering
 261          *           the noirq stage.
 262          * 2. false: The EC event handling is automatically disabled as
 263          *           soon as the EC driver is stopped.
 264          */
 265         if (ec_freeze_events)
 266                 return acpi_ec_started(ec);
 267         else
 268                 return test_bit(EC_FLAGS_STARTED, &ec->flags);
 269 }
 270
 271 static bool acpi_ec_flushed(struct acpi_ec *ec)
 272 {
 273         return ec->reference_count == 1;
 274 }
 275
 276 /* --------------------------------------------------------------------------
 277  *                           EC Registers
 278  * -------------------------------------------------------------------------- */
 279
 280 static inline u8 acpi_ec_read_status(struct acpi_ec *ec)
 281 {
 282         u8 x = inb(ec->command_addr);
 283
 284         ec_dbg_raw("EC_SC(R) = 0x%2.2x "
 285                    "SCI_EVT=%d BURST=%d CMD=%d IBF=%d OBF=%d",
 286                    x,
 287                    !!(x & ACPI_EC_FLAG_SCI),
 288                    !!(x & ACPI_EC_FLAG_BURST),
 289                    !!(x & ACPI_EC_FLAG_CMD),
 290                    !!(x & ACPI_EC_FLAG_IBF),
 291                    !!(x & ACPI_EC_FLAG_OBF));
 292         return x;
 293 }
 294
 295 static inline u8 acpi_ec_read_data(struct acpi_ec *ec)
 296 {
 297         u8 x = inb(ec->data_addr);
 298
 299         ec->timestamp = jiffies;
 300         ec_dbg_raw("EC_DATA(R) = 0x%2.2x", x);
 301         return x;
 302 }
 303
 304 static inline void acpi_ec_write_cmd(struct acpi_ec *ec, u8 command)
 305 {
 306         ec_dbg_raw("EC_SC(W) = 0x%2.2x", command);
 307         outb(command, ec->command_addr);
 308         ec->timestamp = jiffies;
 309 }
 310
 311 static inline void acpi_ec_write_data(struct acpi_ec *ec, u8 data)
 312 {
 313         ec_dbg_raw("EC_DATA(W) = 0x%2.2x", data);
 314         outb(data, ec->data_addr);
 315         ec->timestamp = jiffies;
 316 }
 317
 318 #ifdef DEBUG
 319 static const char *acpi_ec_cmd_string(u8 cmd)
 320 {
 321         switch (cmd) {
 322         case 0x80:
 323                 return "RD_EC";
 324         case 0x81:
 325                 return "WR_EC";
 326         case 0x82:
 327                 return "BE_EC";
 328         case 0x83:
 329                 return "BD_EC";
 330         case 0x84:
 331                 return "QR_EC";
 332         }
 333         return "UNKNOWN";
 334 }
 335 #else
 336 #define acpi_ec_cmd_string(cmd)         "UNDEF"
 337 #endif
 338
 339 /* --------------------------------------------------------------------------
 340  *                           GPE Registers
 341  * -------------------------------------------------------------------------- */
 342
 343 static inline bool acpi_ec_is_gpe_raised(struct acpi_ec *ec)
 344 {
 345         acpi_event_status gpe_status = 0;
 346
 347         (void)acpi_get_gpe_status(NULL, ec->gpe, &gpe_status);
 348         return (gpe_status & ACPI_EVENT_FLAG_STATUS_SET) ? true : false;
 349 }
 350
 351 static inline void acpi_ec_enable_gpe(struct acpi_ec *ec, bool open)
 352 {
 353         if (open)
 354                 acpi_enable_gpe(NULL, ec->gpe);
 355         else {
 356                 BUG_ON(ec->reference_count < 1);
 357                 acpi_set_gpe(NULL, ec->gpe, ACPI_GPE_ENABLE);
 358         }
 359         if (acpi_ec_is_gpe_raised(ec)) {
 360                 /*
 361                  * On some platforms, EN=1 writes cannot trigger GPE. So
 362                  * software need to manually trigger a pseudo GPE event on
 363                  * EN=1 writes.
 364                  */
 365                 ec_dbg_raw("Polling quirk");
 366                 advance_transaction(ec);
 367         }
 368 }
 369
 370 static inline void acpi_ec_disable_gpe(struct acpi_ec *ec, bool close)
 371 {
 372         if (close)
 373                 acpi_disable_gpe(NULL, ec->gpe);
 374         else {
 375                 BUG_ON(ec->reference_count < 1);
 376                 acpi_set_gpe(NULL, ec->gpe, ACPI_GPE_DISABLE);
 377         }
 378 }
 379
 380 static inline void acpi_ec_clear_gpe(struct acpi_ec *ec)
 381 {
 382         /*
 383          * GPE STS is a W1C register, which means:
 384          * 1. Software can clear it without worrying about clearing other
 385          *    GPEs' STS bits when the hardware sets them in parallel.
 386          * 2. As long as software can ensure only clearing it when it is
 387          *    set, hardware won't set it in parallel.
 388          * So software can clear GPE in any contexts.
 389          * Warning: do not move the check into advance_transaction() as the
 390          * EC commands will be sent without GPE raised.
 391          */
 392         if (!acpi_ec_is_gpe_raised(ec))
 393                 return;
 394         acpi_clear_gpe(NULL, ec->gpe);
 395 }
 396
 397 /* --------------------------------------------------------------------------
 398  *                           Transaction Management
 399  * -------------------------------------------------------------------------- */
 400
 401 static void acpi_ec_submit_request(struct acpi_ec *ec)
 402 {
 403         ec->reference_count++;
 404         if (test_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags) &&
 405             ec->reference_count == 1)
 406                 acpi_ec_enable_gpe(ec, true);
 407 }
 408
 409 static void acpi_ec_complete_request(struct acpi_ec *ec)
 410 {
 411         bool flushed = false;
 412
 413         ec->reference_count--;
 414         if (test_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags) &&
 415             ec->reference_count == 0)
 416                 acpi_ec_disable_gpe(ec, true);
 417         flushed = acpi_ec_flushed(ec);
 418         if (flushed)
 419                 wake_up(&ec->wait);
 420 }
 421
 422 static void acpi_ec_set_storm(struct acpi_ec *ec, u8 flag)
 423 {
 424         if (!test_bit(flag, &ec->flags)) {
 425                 acpi_ec_disable_gpe(ec, false);
 426                 ec_dbg_drv("Polling enabled");
 427                 set_bit(flag, &ec->flags);
 428         }
 429 }
 430
 431 static void acpi_ec_clear_storm(struct acpi_ec *ec, u8 flag)
 432 {
 433         if (test_bit(flag, &ec->flags)) {
 434                 clear_bit(flag, &ec->flags);
 435                 acpi_ec_enable_gpe(ec, false);
 436                 ec_dbg_drv("Polling disabled");
 437         }
 438 }
 439
 440 /*
 441  * acpi_ec_submit_flushable_request() - Increase the reference count unless
 442  *                                      the flush operation is not in
 443  *                                      progress
 444  * @ec: the EC device
 445  *
 446  * This function must be used before taking a new action that should hold
 447  * the reference count.  If this function returns false, then the action
 448  * must be discarded or it will prevent the flush operation from being
 449  * completed.
 450  */
 451 static bool acpi_ec_submit_flushable_request(struct acpi_ec *ec)
 452 {
 453         if (!acpi_ec_started(ec))
 454                 return false;
 455         acpi_ec_submit_request(ec);
 456         return true;
 457 }
 458
 459 static void acpi_ec_submit_query(struct acpi_ec *ec)
 460 {
 461         if (acpi_ec_event_enabled(ec) &&
 462             !test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags)) {
 463                 ec_dbg_evt("Command(%s) submitted/blocked",
 464                            acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
 465                 ec->nr_pending_queries++;
 466                 schedule_work(&ec->work);
 467         }
 468 }
 469
 470 static void acpi_ec_complete_query(struct acpi_ec *ec)
 471 {
 472         if (test_bit(EC_FLAGS_QUERY_PENDING, &ec->flags)) {
 473                 clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
 474                 ec_dbg_evt("Command(%s) unblocked",
 475                            acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
 476         }
 477 }
 478
 479 static inline void __acpi_ec_enable_event(struct acpi_ec *ec)
 480 {
 481         if (!test_and_set_bit(EC_FLAGS_QUERY_ENABLED, &ec->flags))
 482                 ec_log_drv("event unblocked");
 483         if (!test_bit(EC_FLAGS_QUERY_PENDING, &ec->flags))
 484                 advance_transaction(ec);
 485 }
 486
 487 static inline void __acpi_ec_disable_event(struct acpi_ec *ec)
 488 {
 489         if (test_and_clear_bit(EC_FLAGS_QUERY_ENABLED, &ec->flags))
 490                 ec_log_drv("event blocked");
 491 }
 492
 493 /*
 494  * Process _Q events that might have accumulated in the EC.
 495  * Run with locked ec mutex.
 496  */
 497 static void acpi_ec_clear(struct acpi_ec *ec)
 498 {
 499         int i, status;
 500         u8 value = 0;
 501
 502         for (i = 0; i < ACPI_EC_CLEAR_MAX; i++) {
 503                 status = acpi_ec_query(ec, &value);
 504                 if (status || !value)
 505                         break;
 506         }
 507         if (unlikely(i == ACPI_EC_CLEAR_MAX))
 508                 pr_warn("Warning: Maximum of %d stale EC events cleared\n", i);
 509         else
 510                 pr_info("%d stale EC events cleared\n", i);
 511 }
 512
 513 static void acpi_ec_enable_event(struct acpi_ec *ec)
 514 {
 515         unsigned long flags;
 516
 517         spin_lock_irqsave(&ec->lock, flags);
 518         if (acpi_ec_started(ec))
 519                 __acpi_ec_enable_event(ec);
 520         spin_unlock_irqrestore(&ec->lock, flags);
 521
 522         /* Drain additional events if hardware requires that */
 523         if (EC_FLAGS_CLEAR_ON_RESUME)
 524                 acpi_ec_clear(ec);
 525 }
 526
 527 static bool acpi_ec_query_flushed(struct acpi_ec *ec)
 528 {
 529         bool flushed;
 530         unsigned long flags;
 531
 532         spin_lock_irqsave(&ec->lock, flags);
 533         flushed = !ec->nr_pending_queries;
 534         spin_unlock_irqrestore(&ec->lock, flags);
 535         return flushed;
 536 }
 537
 538 static void __acpi_ec_flush_event(struct acpi_ec *ec)
 539 {
 540         /*
 541          * When ec_freeze_events is true, we need to flush events in
 542          * the proper position before entering the noirq stage.
 543          */
 544         wait_event(ec->wait, acpi_ec_query_flushed(ec));
 545         if (ec_query_wq)
 546                 flush_workqueue(ec_query_wq);
 547 }
 548
 549 static void acpi_ec_disable_event(struct acpi_ec *ec)
 550 {
 551         unsigned long flags;
 552
 553         spin_lock_irqsave(&ec->lock, flags);
 554         __acpi_ec_disable_event(ec);
 555         spin_unlock_irqrestore(&ec->lock, flags);
 556         __acpi_ec_flush_event(ec);
 557 }
 558
 559 static bool acpi_ec_guard_event(struct acpi_ec *ec)
 560 {
 561         bool guarded = true;
 562         unsigned long flags;
 563
 564         spin_lock_irqsave(&ec->lock, flags);
 565         /*
 566          * If firmware SCI_EVT clearing timing is "event", we actually
 567          * don't know when the SCI_EVT will be cleared by firmware after
 568          * evaluating _Qxx, so we need to re-check SCI_EVT after waiting an
 569          * acceptable period.
 570          *
 571          * The guarding period begins when EC_FLAGS_QUERY_PENDING is
 572          * flagged, which means SCI_EVT check has just been performed.
 573          * But if the current transaction is ACPI_EC_COMMAND_QUERY, the
 574          * guarding should have already been performed (via
 575          * EC_FLAGS_QUERY_GUARDING) and should not be applied so that the
 576          * ACPI_EC_COMMAND_QUERY transaction can be transitioned into
 577          * ACPI_EC_COMMAND_POLL state immediately.
 578          */
 579         if (ec_event_clearing == ACPI_EC_EVT_TIMING_STATUS ||
 580             ec_event_clearing == ACPI_EC_EVT_TIMING_QUERY ||
 581             !test_bit(EC_FLAGS_QUERY_PENDING, &ec->flags) ||
 582             (ec->curr && ec->curr->command == ACPI_EC_COMMAND_QUERY))
 583                 guarded = false;
 584         spin_unlock_irqrestore(&ec->lock, flags);
 585         return guarded;
 586 }
 587
 588 static int ec_transaction_polled(struct acpi_ec *ec)
 589 {
 590         unsigned long flags;
 591         int ret = 0;
 592
 593         spin_lock_irqsave(&ec->lock, flags);
 594         if (ec->curr && (ec->curr->flags & ACPI_EC_COMMAND_POLL))
 595                 ret = 1;
 596         spin_unlock_irqrestore(&ec->lock, flags);
 597         return ret;
 598 }
 599
 600 static int ec_transaction_completed(struct acpi_ec *ec)
 601 {
 602         unsigned long flags;
 603         int ret = 0;
 604
 605         spin_lock_irqsave(&ec->lock, flags);
 606         if (ec->curr && (ec->curr->flags & ACPI_EC_COMMAND_COMPLETE))
 607                 ret = 1;
 608         spin_unlock_irqrestore(&ec->lock, flags);
 609         return ret;
 610 }
 611
 612 static inline void ec_transaction_transition(struct acpi_ec *ec, unsigned long flag)
 613 {
 614         ec->curr->flags |= flag;
 615         if (ec->curr->command == ACPI_EC_COMMAND_QUERY) {
 616                 if (ec_event_clearing == ACPI_EC_EVT_TIMING_STATUS &&
 617                     flag == ACPI_EC_COMMAND_POLL)
 618                         acpi_ec_complete_query(ec);
 619                 if (ec_event_clearing == ACPI_EC_EVT_TIMING_QUERY &&
 620                     flag == ACPI_EC_COMMAND_COMPLETE)
 621                         acpi_ec_complete_query(ec);
 622                 if (ec_event_clearing == ACPI_EC_EVT_TIMING_EVENT &&
 623                     flag == ACPI_EC_COMMAND_COMPLETE)
 624                         set_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags);
 625         }
 626 }
 627
 628 static void advance_transaction(struct acpi_ec *ec)
 629 {
 630         struct transaction *t;
 631         u8 status;
 632         bool wakeup = false;
 633
 634         ec_dbg_stm("%s (%d)", in_interrupt() ? "IRQ" : "TASK",
 635                    smp_processor_id());
 636         /*
 637          * By always clearing STS before handling all indications, we can
 638          * ensure a hardware STS 0->1 change after this clearing can always
 639          * trigger a GPE interrupt.
 640          */
 641         acpi_ec_clear_gpe(ec);
 642         status = acpi_ec_read_status(ec);
 643         t = ec->curr;
 644         /*
 645          * Another IRQ or a guarded polling mode advancement is detected,
 646          * the next QR_EC submission is then allowed.
 647          */
 648         if (!t || !(t->flags & ACPI_EC_COMMAND_POLL)) {
 649                 if (ec_event_clearing == ACPI_EC_EVT_TIMING_EVENT &&
 650                     (!ec->nr_pending_queries ||
 651                      test_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags))) {
 652                         clear_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags);
 653                         acpi_ec_complete_query(ec);
 654                 }
 655         }
 656         if (!t)
 657                 goto err;
 658         if (t->flags & ACPI_EC_COMMAND_POLL) {
 659                 if (t->wlen > t->wi) {
 660                         if ((status & ACPI_EC_FLAG_IBF) == 0)
 661                                 acpi_ec_write_data(ec, t->wdata[t->wi++]);
 662                         else
 663                                 goto err;
 664                 } else if (t->rlen > t->ri) {
 665                         if ((status & ACPI_EC_FLAG_OBF) == 1) {
 666                                 t->rdata[t->ri++] = acpi_ec_read_data(ec);
 667                                 if (t->rlen == t->ri) {
 668                                         ec_transaction_transition(ec, ACPI_EC_COMMAND_COMPLETE);
 669                                         if (t->command == ACPI_EC_COMMAND_QUERY)
 670                                                 ec_dbg_evt("Command(%s) completed by hardware",
 671                                                            acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
 672                                         wakeup = true;
 673                                 }
 674                         } else
 675                                 goto err;
 676                 } else if (t->wlen == t->wi &&
 677                            (status & ACPI_EC_FLAG_IBF) == 0) {
 678                         ec_transaction_transition(ec, ACPI_EC_COMMAND_COMPLETE);
 679                         wakeup = true;
 680                 }
 681                 goto out;
 682         } else {
 683                 if (EC_FLAGS_QUERY_HANDSHAKE &&
 684                     !(status & ACPI_EC_FLAG_SCI) &&
 685                     (t->command == ACPI_EC_COMMAND_QUERY)) {
 686                         ec_transaction_transition(ec, ACPI_EC_COMMAND_POLL);
 687                         t->rdata[t->ri++] = 0x00;
 688                         ec_transaction_transition(ec, ACPI_EC_COMMAND_COMPLETE);
 689                         ec_dbg_evt("Command(%s) completed by software",
 690                                    acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
 691                         wakeup = true;
 692                 } else if ((status & ACPI_EC_FLAG_IBF) == 0) {
 693                         acpi_ec_write_cmd(ec, t->command);
 694                         ec_transaction_transition(ec, ACPI_EC_COMMAND_POLL);
 695                 } else
 696                         goto err;
 697                 goto out;
 698         }
 699 err:
 700         /*
 701          * If SCI bit is set, then don't think it's a false IRQ
 702          * otherwise will take a not handled IRQ as a false one.
 703          */
 704         if (!(status & ACPI_EC_FLAG_SCI)) {
 705                 if (in_interrupt() && t) {
 706                         if (t->irq_count < ec_storm_threshold)
 707                                 ++t->irq_count;
 708                         /* Allow triggering on 0 threshold */
 709                         if (t->irq_count == ec_storm_threshold)
 710                                 acpi_ec_set_storm(ec, EC_FLAGS_COMMAND_STORM);
 711                 }
 712         }
 713 out:
 714         if (status & ACPI_EC_FLAG_SCI)
 715                 acpi_ec_submit_query(ec);
 716         if (wakeup && in_interrupt())
 717                 wake_up(&ec->wait);
 718 }
 719
 720 static void start_transaction(struct acpi_ec *ec)
 721 {
 722         ec->curr->irq_count = ec->curr->wi = ec->curr->ri = 0;
 723         ec->curr->flags = 0;
 724 }
 725
 726 static int ec_guard(struct acpi_ec *ec)
 727 {
 728         unsigned long guard = usecs_to_jiffies(ec_polling_guard);
 729         unsigned long timeout = ec->timestamp + guard;
 730
 731         /* Ensure guarding period before polling EC status */
 732         do {
 733                 if (ec_busy_polling) {
 734                         /* Perform busy polling */
 735                         if (ec_transaction_completed(ec))
 736                                 return 0;
 737                         udelay(jiffies_to_usecs(guard));
 738                 } else {
 739                         /*
 740                          * Perform wait polling
 741                          * 1. Wait the transaction to be completed by the
 742                          *    GPE handler after the transaction enters
 743                          *    ACPI_EC_COMMAND_POLL state.
 744                          * 2. A special guarding logic is also required
 745                          *    for event clearing mode "event" before the
 746                          *    transaction enters ACPI_EC_COMMAND_POLL
 747                          *    state.
 748                          */
 749                         if (!ec_transaction_polled(ec) &&
 750                             !acpi_ec_guard_event(ec))
 751                                 break;
 752                         if (wait_event_timeout(ec->wait,
 753                                                ec_transaction_completed(ec),
 754                                                guard))
 755                                 return 0;
 756                 }
 757         } while (time_before(jiffies, timeout));
 758         return -ETIME;
 759 }
 760
 761 static int ec_poll(struct acpi_ec *ec)
 762 {
 763         unsigned long flags;
 764         int repeat = 5; /* number of command restarts */
 765
 766         while (repeat--) {
 767                 unsigned long delay = jiffies +
 768                         msecs_to_jiffies(ec_delay);
 769                 do {
 770                         if (!ec_guard(ec))
 771                                 return 0;
 772                         spin_lock_irqsave(&ec->lock, flags);
 773                         advance_transaction(ec);
 774                         spin_unlock_irqrestore(&ec->lock, flags);
 775                 } while (time_before(jiffies, delay));
 776                 pr_debug("controller reset, restart transaction\n");
 777                 spin_lock_irqsave(&ec->lock, flags);
 778                 start_transaction(ec);
 779                 spin_unlock_irqrestore(&ec->lock, flags);
 780         }
 781         return -ETIME;
 782 }
 783
 784 static int acpi_ec_transaction_unlocked(struct acpi_ec *ec,
 785                                         struct transaction *t)
 786 {
 787         unsigned long tmp;
 788         int ret = 0;
 789
 790         /* start transaction */
 791         spin_lock_irqsave(&ec->lock, tmp);
 792         /* Enable GPE for command processing (IBF=0/OBF=1) */
 793         if (!acpi_ec_submit_flushable_request(ec)) {
 794                 ret = -EINVAL;
 795                 goto unlock;
 796         }
 797         ec_dbg_ref(ec, "Increase command");
 798         /* following two actions should be kept atomic */
 799         ec->curr = t;
 800         ec_dbg_req("Command(%s) started", acpi_ec_cmd_string(t->command));
 801         start_transaction(ec);
 802         spin_unlock_irqrestore(&ec->lock, tmp);
 803
 804         ret = ec_poll(ec);
 805
 806         spin_lock_irqsave(&ec->lock, tmp);
 807         if (t->irq_count == ec_storm_threshold)
 808                 acpi_ec_clear_storm(ec, EC_FLAGS_COMMAND_STORM);
 809         ec_dbg_req("Command(%s) stopped", acpi_ec_cmd_string(t->command));
 810         ec->curr = NULL;
 811         /* Disable GPE for command processing (IBF=0/OBF=1) */
 812         acpi_ec_complete_request(ec);
 813         ec_dbg_ref(ec, "Decrease command");
 814 unlock:
 815         spin_unlock_irqrestore(&ec->lock, tmp);
 816         return ret;
 817 }
 818
 819 static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t)
 820 {
 821         int status;
 822         u32 glk;
 823
 824         if (!ec || (!t) || (t->wlen && !t->wdata) || (t->rlen && !t->rdata))
 825                 return -EINVAL;
 826         if (t->rdata)
 827                 memset(t->rdata, 0, t->rlen);
 828
 829         mutex_lock(&ec->mutex);
 830         if (ec->global_lock) {
 831                 status = acpi_acquire_global_lock(ACPI_EC_UDELAY_GLK, &glk);
 832                 if (ACPI_FAILURE(status)) {
 833                         status = -ENODEV;
 834                         goto unlock;
 835                 }
 836         }
 837
 838         status = acpi_ec_transaction_unlocked(ec, t);
 839
 840         if (ec->global_lock)
 841                 acpi_release_global_lock(glk);
 842 unlock:
 843         mutex_unlock(&ec->mutex);
 844         return status;
 845 }
 846
 847 static int acpi_ec_burst_enable(struct acpi_ec *ec)
 848 {
 849         u8 d;
 850         struct transaction t = {.command = ACPI_EC_BURST_ENABLE,
 851                                 .wdata = NULL, .rdata = &d,
 852                                 .wlen = 0, .rlen = 1};
 853
 854         return acpi_ec_transaction(ec, &t);
 855 }
 856
 857 static int acpi_ec_burst_disable(struct acpi_ec *ec)
 858 {
 859         struct transaction t = {.command = ACPI_EC_BURST_DISABLE,
 860                                 .wdata = NULL, .rdata = NULL,
 861                                 .wlen = 0, .rlen = 0};
 862
 863         return (acpi_ec_read_status(ec) & ACPI_EC_FLAG_BURST) ?
 864                                 acpi_ec_transaction(ec, &t) : 0;
 865 }
 866
 867 static int acpi_ec_read(struct acpi_ec *ec, u8 address, u8 *data)
 868 {
 869         int result;
 870         u8 d;
 871         struct transaction t = {.command = ACPI_EC_COMMAND_READ,
 872                                 .wdata = &address, .rdata = &d,
 873                                 .wlen = 1, .rlen = 1};
 874
 875         result = acpi_ec_transaction(ec, &t);
 876         *data = d;
 877         return result;
 878 }
 879
 880 static int acpi_ec_write(struct acpi_ec *ec, u8 address, u8 data)
 881 {
 882         u8 wdata[2] = { address, data };
 883         struct transaction t = {.command = ACPI_EC_COMMAND_WRITE,
 884                                 .wdata = wdata, .rdata = NULL,
 885                                 .wlen = 2, .rlen = 0};
 886
 887         return acpi_ec_transaction(ec, &t);
 888 }
 889
 890 int ec_read(u8 addr, u8 *val)
 891 {
 892         int err;
 893         u8 temp_data;
 894
 895         if (!first_ec)
 896                 return -ENODEV;
 897
 898         err = acpi_ec_read(first_ec, addr, &temp_data);
 899
 900         if (!err) {
 901                 *val = temp_data;
 902                 return 0;
 903         }
 904         return err;
 905 }
 906 EXPORT_SYMBOL(ec_read);
 907
 908 int ec_write(u8 addr, u8 val)
 909 {
 910         int err;
 911
 912         if (!first_ec)
 913                 return -ENODEV;
 914
 915         err = acpi_ec_write(first_ec, addr, val);
 916
 917         return err;
 918 }
 919 EXPORT_SYMBOL(ec_write);
 920
 921 int ec_transaction(u8 command,
 922                    const u8 *wdata, unsigned wdata_len,
 923                    u8 *rdata, unsigned rdata_len)
 924 {
 925         struct transaction t = {.command = command,
 926                                 .wdata = wdata, .rdata = rdata,
 927                                 .wlen = wdata_len, .rlen = rdata_len};
 928
 929         if (!first_ec)
 930                 return -ENODEV;
 931
 932         return acpi_ec_transaction(first_ec, &t);
 933 }
 934 EXPORT_SYMBOL(ec_transaction);
 935
 936 /* Get the handle to the EC device */
 937 acpi_handle ec_get_handle(void)
 938 {
 939         if (!first_ec)
 940                 return NULL;
 941         return first_ec->handle;
 942 }
 943 EXPORT_SYMBOL(ec_get_handle);
 944
 945 static void acpi_ec_start(struct acpi_ec *ec, bool resuming)
 946 {
 947         unsigned long flags;
 948
 949         spin_lock_irqsave(&ec->lock, flags);
 950         if (!test_and_set_bit(EC_FLAGS_STARTED, &ec->flags)) {
 951                 ec_dbg_drv("Starting EC");
 952                 /* Enable GPE for event processing (SCI_EVT=1) */
 953                 if (!resuming) {
 954                         acpi_ec_submit_request(ec);
 955                         ec_dbg_ref(ec, "Increase driver");
 956                 }
 957                 ec_log_drv("EC started");
 958         }
 959         spin_unlock_irqrestore(&ec->lock, flags);
 960 }
 961
 962 static bool acpi_ec_stopped(struct acpi_ec *ec)
 963 {
 964         unsigned long flags;
 965         bool flushed;
 966
 967         spin_lock_irqsave(&ec->lock, flags);
 968         flushed = acpi_ec_flushed(ec);
 969         spin_unlock_irqrestore(&ec->lock, flags);
 970         return flushed;
 971 }
 972
 973 static void acpi_ec_stop(struct acpi_ec *ec, bool suspending)
 974 {
 975         unsigned long flags;
 976
 977         spin_lock_irqsave(&ec->lock, flags);
 978         if (acpi_ec_started(ec)) {
 979                 ec_dbg_drv("Stopping EC");
 980                 set_bit(EC_FLAGS_STOPPED, &ec->flags);
 981                 spin_unlock_irqrestore(&ec->lock, flags);
 982                 wait_event(ec->wait, acpi_ec_stopped(ec));
 983                 spin_lock_irqsave(&ec->lock, flags);
 984                 /* Disable GPE for event processing (SCI_EVT=1) */
 985                 if (!suspending) {
 986                         acpi_ec_complete_request(ec);
 987                         ec_dbg_ref(ec, "Decrease driver");
 988                 } else if (!ec_freeze_events)
 989                         __acpi_ec_disable_event(ec);
 990                 clear_bit(EC_FLAGS_STARTED, &ec->flags);
 991                 clear_bit(EC_FLAGS_STOPPED, &ec->flags);
 992                 ec_log_drv("EC stopped");
 993         }
 994         spin_unlock_irqrestore(&ec->lock, flags);
 995 }
 996
 997 void acpi_ec_block_transactions(void)
 998 {
 999         struct acpi_ec *ec = first_ec;
1000
1001         if (!ec)
1002                 return;
1003
1004         mutex_lock(&ec->mutex);
1005         /* Prevent transactions from being carried out */
1006         acpi_ec_stop(ec, true);
1007         mutex_unlock(&ec->mutex);
1008 }
1009
1010 void acpi_ec_unblock_transactions(void)
1011 {
1012         /*
1013          * Allow transactions to happen again (this function is called from
1014          * atomic context during wakeup, so we don't need to acquire the mutex).
1015          */
1016         if (first_ec)
1017                 acpi_ec_start(first_ec, true);
1018 }
1019
1020 /* --------------------------------------------------------------------------
1021                                 Event Management
1022    -------------------------------------------------------------------------- */
1023 static struct acpi_ec_query_handler *
1024 acpi_ec_get_query_handler(struct acpi_ec_query_handler *handler)
1025 {
1026         if (handler)
1027                 kref_get(&handler->kref);
1028         return handler;
1029 }
1030
1031 static struct acpi_ec_query_handler *
1032 acpi_ec_get_query_handler_by_value(struct acpi_ec *ec, u8 value)
1033 {
1034         struct acpi_ec_query_handler *handler;
1035         bool found = false;
1036
1037         mutex_lock(&ec->mutex);
1038         list_for_each_entry(handler, &ec->list, node) {
1039                 if (value == handler->query_bit) {
1040                         found = true;
1041                         break;
1042                 }
1043         }
1044         mutex_unlock(&ec->mutex);
1045         return found ? acpi_ec_get_query_handler(handler) : NULL;
1046 }
1047
1048 static void acpi_ec_query_handler_release(struct kref *kref)
1049 {
1050         struct acpi_ec_query_handler *handler =
1051                 container_of(kref, struct acpi_ec_query_handler, kref);
1052
1053         kfree(handler);
1054 }
1055
1056 static void acpi_ec_put_query_handler(struct acpi_ec_query_handler *handler)
1057 {
1058         kref_put(&handler->kref, acpi_ec_query_handler_release);
1059 }
1060
1061 int acpi_ec_add_query_handler(struct acpi_ec *ec, u8 query_bit,
1062                               acpi_handle handle, acpi_ec_query_func func,
1063                               void *data)
1064 {
1065         struct acpi_ec_query_handler *handler =
1066             kzalloc(sizeof(struct acpi_ec_query_handler), GFP_KERNEL);
1067
1068         if (!handler)
1069                 return -ENOMEM;
1070
1071         handler->query_bit = query_bit;
1072         handler->handle = handle;
1073         handler->func = func;
1074         handler->data = data;
1075         mutex_lock(&ec->mutex);
1076         kref_init(&handler->kref);
1077         list_add(&handler->node, &ec->list);
1078         mutex_unlock(&ec->mutex);
1079         return 0;
1080 }
1081 EXPORT_SYMBOL_GPL(acpi_ec_add_query_handler);
1082
1083 static void acpi_ec_remove_query_handlers(struct acpi_ec *ec,
1084                                           bool remove_all, u8 query_bit)
1085 {
1086         struct acpi_ec_query_handler *handler, *tmp;
1087         LIST_HEAD(free_list);
1088
1089         mutex_lock(&ec->mutex);
1090         list_for_each_entry_safe(handler, tmp, &ec->list, node) {
1091                 if (remove_all || query_bit == handler->query_bit) {
1092                         list_del_init(&handler->node);
1093                         list_add(&handler->node, &free_list);
1094                 }
1095         }
1096         mutex_unlock(&ec->mutex);
1097         list_for_each_entry_safe(handler, tmp, &free_list, node)
1098                 acpi_ec_put_query_handler(handler);
1099 }
1100
1101 void acpi_ec_remove_query_handler(struct acpi_ec *ec, u8 query_bit)
1102 {
1103         acpi_ec_remove_query_handlers(ec, false, query_bit);
1104 }
1105 EXPORT_SYMBOL_GPL(acpi_ec_remove_query_handler);
1106
1107 static struct acpi_ec_query *acpi_ec_create_query(u8 *pval)
1108 {
1109         struct acpi_ec_query *q;
1110         struct transaction *t;
1111
1112         q = kzalloc(sizeof (struct acpi_ec_query), GFP_KERNEL);
1113         if (!q)
1114                 return NULL;
1115         INIT_WORK(&q->work, acpi_ec_event_processor);
1116         t = &q->transaction;
1117         t->command = ACPI_EC_COMMAND_QUERY;
1118         t->rdata = pval;
1119         t->rlen = 1;
1120         return q;
1121 }
1122
1123 static void acpi_ec_delete_query(struct acpi_ec_query *q)
1124 {
1125         if (q) {
1126                 if (q->handler)
1127                         acpi_ec_put_query_handler(q->handler);
1128                 kfree(q);
1129         }
1130 }
1131
1132 static void acpi_ec_event_processor(struct work_struct *work)
1133 {
1134         struct acpi_ec_query *q = container_of(work, struct acpi_ec_query, work);
1135         struct acpi_ec_query_handler *handler = q->handler;
1136
1137         ec_dbg_evt("Query(0x%02x) started", handler->query_bit);
1138         if (handler->func)
1139                 handler->func(handler->data);
1140         else if (handler->handle)
1141                 acpi_evaluate_object(handler->handle, NULL, NULL, NULL);
1142         ec_dbg_evt("Query(0x%02x) stopped", handler->query_bit);
1143         acpi_ec_delete_query(q);
1144 }
1145
1146 static int acpi_ec_query(struct acpi_ec *ec, u8 *data)
1147 {
1148         u8 value = 0;
1149         int result;
1150         struct acpi_ec_query *q;
1151
1152         q = acpi_ec_create_query(&value);
1153         if (!q)
1154                 return -ENOMEM;
1155
1156         /*
1157          * Query the EC to find out which _Qxx method we need to evaluate.
1158          * Note that successful completion of the query causes the ACPI_EC_SCI
1159          * bit to be cleared (and thus clearing the interrupt source).
1160          */
1161         result = acpi_ec_transaction(ec, &q->transaction);
1162         if (!value)
1163                 result = -ENODATA;
1164         if (result)
1165                 goto err_exit;
1166
1167         q->handler = acpi_ec_get_query_handler_by_value(ec, value);
1168         if (!q->handler) {
1169                 result = -ENODATA;
1170                 goto err_exit;
1171         }
1172
1173         /*
1174          * It is reported that _Qxx are evaluated in a parallel way on
1175          * Windows:
1176          * https://bugzilla.kernel.org/show_bug.cgi?id=94411
1177          *
1178          * Put this log entry before schedule_work() in order to make
1179          * it appearing before any other log entries occurred during the
1180          * work queue execution.
1181          */
1182         ec_dbg_evt("Query(0x%02x) scheduled", value);
1183         if (!queue_work(ec_query_wq, &q->work)) {
1184                 ec_dbg_evt("Query(0x%02x) overlapped", value);
1185                 result = -EBUSY;
1186         }
1187
1188 err_exit:
1189         if (result)
1190                 acpi_ec_delete_query(q);
1191         if (data)
1192                 *data = value;
1193         return result;
1194 }
1195
1196 static void acpi_ec_check_event(struct acpi_ec *ec)
1197 {
1198         unsigned long flags;
1199
1200         if (ec_event_clearing == ACPI_EC_EVT_TIMING_EVENT) {
1201                 if (ec_guard(ec)) {
1202                         spin_lock_irqsave(&ec->lock, flags);
1203                         /*
1204                          * Take care of the SCI_EVT unless no one else is
1205                          * taking care of it.
1206                          */
1207                         if (!ec->curr)
1208                                 advance_transaction(ec);
1209                         spin_unlock_irqrestore(&ec->lock, flags);
1210                 }
1211         }
1212 }
1213
1214 static void acpi_ec_event_handler(struct work_struct *work)
1215 {
1216         unsigned long flags;
1217         struct acpi_ec *ec = container_of(work, struct acpi_ec, work);
1218
1219         ec_dbg_evt("Event started");
1220
1221         spin_lock_irqsave(&ec->lock, flags);
1222         while (ec->nr_pending_queries) {
1223                 spin_unlock_irqrestore(&ec->lock, flags);
1224                 (void)acpi_ec_query(ec, NULL);
1225                 spin_lock_irqsave(&ec->lock, flags);
1226                 ec->nr_pending_queries--;
1227                 /*
1228                  * Before exit, make sure that this work item can be
1229                  * scheduled again. There might be QR_EC failures, leaving
1230                  * EC_FLAGS_QUERY_PENDING uncleared and preventing this work
1231                  * item from being scheduled again.
1232                  */
1233                 if (!ec->nr_pending_queries) {
1234                         if (ec_event_clearing == ACPI_EC_EVT_TIMING_STATUS ||
1235                             ec_event_clearing == ACPI_EC_EVT_TIMING_QUERY)
1236                                 acpi_ec_complete_query(ec);
1237                 }
1238         }
1239         spin_unlock_irqrestore(&ec->lock, flags);
1240
1241         ec_dbg_evt("Event stopped");
1242
1243         acpi_ec_check_event(ec);
1244 }
1245
1246 static u32 acpi_ec_gpe_handler(acpi_handle gpe_device,
1247         u32 gpe_number, void *data)
1248 {
1249         unsigned long flags;
1250         struct acpi_ec *ec = data;
1251
1252         spin_lock_irqsave(&ec->lock, flags);
1253         advance_transaction(ec);
1254         spin_unlock_irqrestore(&ec->lock, flags);
1255         return ACPI_INTERRUPT_HANDLED;
1256 }
1257
1258 /* --------------------------------------------------------------------------
1259  *                           Address Space Management
1260  * -------------------------------------------------------------------------- */
1261
1262 static acpi_status
1263 acpi_ec_space_handler(u32 function, acpi_physical_address address,
1264                       u32 bits, u64 *value64,
1265                       void *handler_context, void *region_context)
1266 {
1267         struct acpi_ec *ec = handler_context;
1268         int result = 0, i, bytes = bits / 8;
1269         u8 *value = (u8 *)value64;
1270
1271         if ((address > 0xFF) || !value || !handler_context)
1272                 return AE_BAD_PARAMETER;
1273
1274         if (function != ACPI_READ && function != ACPI_WRITE)
1275                 return AE_BAD_PARAMETER;
1276
1277         if (ec_busy_polling || bits > 8)
1278                 acpi_ec_burst_enable(ec);
1279
1280         for (i = 0; i < bytes; ++i, ++address, ++value)
1281                 result = (function == ACPI_READ) ?
1282                         acpi_ec_read(ec, address, value) :
1283                         acpi_ec_write(ec, address, *value);
1284
1285         if (ec_busy_polling || bits > 8)
1286                 acpi_ec_burst_disable(ec);
1287
1288         switch (result) {
1289         case -EINVAL:
1290                 return AE_BAD_PARAMETER;
1291         case -ENODEV:
1292                 return AE_NOT_FOUND;
1293         case -ETIME:
1294                 return AE_TIME;
1295         default:
1296                 return AE_OK;
1297         }
1298 }
1299
1300 /* --------------------------------------------------------------------------
1301  *                             Driver Interface
1302  * -------------------------------------------------------------------------- */
1303
1304 static acpi_status
1305 ec_parse_io_ports(struct acpi_resource *resource, void *context);
1306
1307 static struct acpi_ec *make_acpi_ec(void)
1308 {
1309         struct acpi_ec *ec = kzalloc(sizeof(struct acpi_ec), GFP_KERNEL);
1310
1311         if (!ec)
1312                 return NULL;
1313         mutex_init(&ec->mutex);
1314         init_waitqueue_head(&ec->wait);
1315         INIT_LIST_HEAD(&ec->list);
1316         spin_lock_init(&ec->lock);
1317         INIT_WORK(&ec->work, acpi_ec_event_handler);
1318         ec->timestamp = jiffies;
1319         return ec;
1320 }
1321
1322 static acpi_status
1323 acpi_ec_register_query_methods(acpi_handle handle, u32 level,
1324                                void *context, void **return_value)
1325 {
1326         char node_name[5];
1327         struct acpi_buffer buffer = { sizeof(node_name), node_name };
1328         struct acpi_ec *ec = context;
1329         int value = 0;
1330         acpi_status status;
1331
1332         status = acpi_get_name(handle, ACPI_SINGLE_NAME, &buffer);
1333
1334         if (ACPI_SUCCESS(status) && sscanf(node_name, "_Q%x", &value) == 1)
1335                 acpi_ec_add_query_handler(ec, value, handle, NULL, NULL);
1336         return AE_OK;
1337 }
1338
1339 static acpi_status
1340 ec_parse_device(acpi_handle handle, u32 Level, void *context, void **retval)
1341 {
1342         acpi_status status;
1343         unsigned long long tmp = 0;
1344         struct acpi_ec *ec = context;
1345
1346         /* clear addr values, ec_parse_io_ports depend on it */
1347         ec->command_addr = ec->data_addr = 0;
1348
1349         status = acpi_walk_resources(handle, METHOD_NAME__CRS,
1350                                      ec_parse_io_ports, ec);
1351         if (ACPI_FAILURE(status))
1352                 return status;
1353
1354         /* Get GPE bit assignment (EC events). */
1355         /* TODO: Add support for _GPE returning a package */
1356         status = acpi_evaluate_integer(handle, "_GPE", NULL, &tmp);
1357         if (ACPI_FAILURE(status))
1358                 return status;
1359         ec->gpe = tmp;
1360         /* Use the global lock for all EC transactions? */
1361         tmp = 0;
1362         acpi_evaluate_integer(handle, "_GLK", NULL, &tmp);
1363         ec->global_lock = tmp;
1364         ec->handle = handle;
1365         return AE_CTRL_TERMINATE;
1366 }
1367
1368 static int ec_install_handlers(struct acpi_ec *ec)
1369 {
1370         acpi_status status;
1371
1372         acpi_ec_start(ec, false);
1373
1374         if (!test_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags)) {
1375                 status = acpi_install_address_space_handler(ec->handle,
1376                                                             ACPI_ADR_SPACE_EC,
1377                                                             &acpi_ec_space_handler,
1378                                                             NULL, ec);
1379                 if (ACPI_FAILURE(status)) {
1380                         if (status == AE_NOT_FOUND) {
1381                                 /*
1382                                  * Maybe OS fails in evaluating the _REG
1383                                  * object. The AE_NOT_FOUND error will be
1384                                  * ignored and OS * continue to initialize
1385                                  * EC.
1386                                  */
1387                                 pr_err("Fail in evaluating the _REG object"
1388                                         " of EC device. Broken bios is suspected.\n");
1389                         } else {
1390                                 acpi_ec_stop(ec, false);
1391                                 return -ENODEV;
1392                         }
1393                 }
1394                 set_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags);
1395         }
1396
1397         if (!test_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags)) {
1398                 status = acpi_install_gpe_raw_handler(NULL, ec->gpe,
1399                                           ACPI_GPE_EDGE_TRIGGERED,
1400                                           &acpi_ec_gpe_handler, ec);
1401                 /* This is not fatal as we can poll EC events */
1402                 if (ACPI_SUCCESS(status)) {
1403                         set_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags);
1404                         if (test_bit(EC_FLAGS_STARTED, &ec->flags) &&
1405                             ec->reference_count >= 1)
1406                                 acpi_ec_enable_gpe(ec, true);
1407                 }
1408         }
1409
1410         return 0;
1411 }
1412
1413 static void ec_remove_handlers(struct acpi_ec *ec)
1414 {
1415         if (test_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags)) {
1416                 if (ACPI_FAILURE(acpi_remove_address_space_handler(ec->handle,
1417                                         ACPI_ADR_SPACE_EC, &acpi_ec_space_handler)))
1418                         pr_err("failed to remove space handler\n");
1419                 clear_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags);
1420         }
1421
1422         /*
1423          * Stops handling the EC transactions after removing the operation
1424          * region handler. This is required because _REG(DISCONNECT)
1425          * invoked during the removal can result in new EC transactions.
1426          *
1427          * Flushes the EC requests and thus disables the GPE before
1428          * removing the GPE handler. This is required by the current ACPICA
1429          * GPE core. ACPICA GPE core will automatically disable a GPE when
1430          * it is indicated but there is no way to handle it. So the drivers
1431          * must disable the GPEs prior to removing the GPE handlers.
1432          */
1433         acpi_ec_stop(ec, false);
1434
1435         if (test_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags)) {
1436                 if (ACPI_FAILURE(acpi_remove_gpe_handler(NULL, ec->gpe,
1437                                         &acpi_ec_gpe_handler)))
1438                         pr_err("failed to remove gpe handler\n");
1439                 clear_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags);
1440         }
1441 }
1442
1443 static struct acpi_ec *acpi_ec_alloc(void)
1444 {
1445         struct acpi_ec *ec;
1446
1447         /* Check for boot EC */
1448         if (boot_ec) {
1449                 ec = boot_ec;
1450                 boot_ec = NULL;
1451                 ec_remove_handlers(ec);
1452                 if (first_ec == ec)
1453                         first_ec = NULL;
1454         } else {
1455                 ec = make_acpi_ec();
1456         }
1457         return ec;
1458 }
1459
1460 static int acpi_ec_add(struct acpi_device *device)
1461 {
1462         struct acpi_ec *ec = NULL;
1463         int ret;
1464
1465         strcpy(acpi_device_name(device), ACPI_EC_DEVICE_NAME);
1466         strcpy(acpi_device_class(device), ACPI_EC_CLASS);
1467
1468         ec = acpi_ec_alloc();
1469         if (!ec)
1470                 return -ENOMEM;
1471         if (ec_parse_device(device->handle, 0, ec, NULL) !=
1472                 AE_CTRL_TERMINATE) {
1473                         kfree(ec);
1474                         return -EINVAL;
1475         }
1476
1477         /* Find and register all query methods */
1478         acpi_walk_namespace(ACPI_TYPE_METHOD, ec->handle, 1,
1479                             acpi_ec_register_query_methods, NULL, ec, NULL);
1480
1481         if (!first_ec)
1482                 first_ec = ec;
1483         device->driver_data = ec;
1484
1485         ret = !!request_region(ec->data_addr, 1, "EC data");
1486         WARN(!ret, "Could not request EC data io port 0x%lx", ec->data_addr);
1487         ret = !!request_region(ec->command_addr, 1, "EC cmd");
1488         WARN(!ret, "Could not request EC cmd io port 0x%lx", ec->command_addr);
1489
1490         pr_info("GPE = 0x%lx, I/O: command/status = 0x%lx, data = 0x%lx\n",
1491                           ec->gpe, ec->command_addr, ec->data_addr);
1492
1493         ret = ec_install_handlers(ec);
1494
1495         /* Reprobe devices depending on the EC */
1496         acpi_walk_dep_device_list(ec->handle);
1497
1498         /* EC is fully operational, allow queries */
1499         acpi_ec_enable_event(ec);
1500         return ret;
1501 }
1502
1503 static int acpi_ec_remove(struct acpi_device *device)
1504 {
1505         struct acpi_ec *ec;
1506
1507         if (!device)
1508                 return -EINVAL;
1509
1510         ec = acpi_driver_data(device);
1511         ec_remove_handlers(ec);
1512         acpi_ec_remove_query_handlers(ec, true, 0);
1513         release_region(ec->data_addr, 1);
1514         release_region(ec->command_addr, 1);
1515         device->driver_data = NULL;
1516         if (ec == first_ec)
1517                 first_ec = NULL;
1518         kfree(ec);
1519         return 0;
1520 }
1521
1522 static acpi_status
1523 ec_parse_io_ports(struct acpi_resource *resource, void *context)
1524 {
1525         struct acpi_ec *ec = context;
1526
1527         if (resource->type != ACPI_RESOURCE_TYPE_IO)
1528                 return AE_OK;
1529
1530         /*
1531          * The first address region returned is the data port, and
1532          * the second address region returned is the status/command
1533          * port.
1534          */
1535         if (ec->data_addr == 0)
1536                 ec->data_addr = resource->data.io.minimum;
1537         else if (ec->command_addr == 0)
1538                 ec->command_addr = resource->data.io.minimum;
1539         else
1540                 return AE_CTRL_TERMINATE;
1541
1542         return AE_OK;
1543 }
1544
1545 static const struct acpi_device_id ec_device_ids[] = {
1546         {"PNP0C09", 0},
1547         {"", 0},
1548 };
1549
1550 int __init acpi_ec_dsdt_probe(void)
1551 {
1552         acpi_status status;
1553         struct acpi_ec *ec;
1554         int ret;
1555
1556         ec = acpi_ec_alloc();
1557         if (!ec)
1558                 return -ENOMEM;
1559         /*
1560          * Finding EC from DSDT if there is no ECDT EC available. When this
1561          * function is invoked, ACPI tables have been fully loaded, we can
1562          * walk namespace now.
1563          */
1564         status = acpi_get_devices(ec_device_ids[0].id,
1565                                   ec_parse_device, ec, NULL);
1566         if (ACPI_FAILURE(status) || !ec->handle) {
1567                 ret = -ENODEV;
1568                 goto error;
1569         }
1570         ret = ec_install_handlers(ec);
1571
1572 error:
1573         if (ret)
1574                 kfree(ec);
1575         else
1576                 first_ec = boot_ec = ec;
1577         return ret;
1578 }
1579
1580 #if 0
1581 /*
1582  * Some EC firmware variations refuses to respond QR_EC when SCI_EVT is not
1583  * set, for which case, we complete the QR_EC without issuing it to the
1584  * firmware.
1585  * https://bugzilla.kernel.org/show_bug.cgi?id=82611
1586  * https://bugzilla.kernel.org/show_bug.cgi?id=97381
1587  */
1588 static int ec_flag_query_handshake(const struct dmi_system_id *id)
1589 {
1590         pr_debug("Detected the EC firmware requiring QR_EC issued when SCI_EVT set\n");
1591         EC_FLAGS_QUERY_HANDSHAKE = 1;
1592         return 0;
1593 }
1594 #endif
1595
1596 /*
1597  * On some hardware it is necessary to clear events accumulated by the EC during
1598  * sleep. These ECs stop reporting GPEs until they are manually polled, if too
1599  * many events are accumulated. (e.g. Samsung Series 5/9 notebooks)
1600  *
1601  * https://bugzilla.kernel.org/show_bug.cgi?id=44161
1602  *
1603  * Ideally, the EC should also be instructed NOT to accumulate events during
1604  * sleep (which Windows seems to do somehow), but the interface to control this
1605  * behaviour is not known at this time.
1606  *
1607  * Models known to be affected are Samsung 530Uxx/535Uxx/540Uxx/550Pxx/900Xxx,
1608  * however it is very likely that other Samsung models are affected.
1609  *
1610  * On systems which don't accumulate _Q events during sleep, this extra check
1611  * should be harmless.
1612  */
1613 static int ec_clear_on_resume(const struct dmi_system_id *id)
1614 {
1615         pr_debug("Detected system needing EC poll on resume.\n");
1616         EC_FLAGS_CLEAR_ON_RESUME = 1;
1617         ec_event_clearing = ACPI_EC_EVT_TIMING_STATUS;
1618         return 0;
1619 }
1620
1621 /*
1622  * Some ECDTs contain wrong register addresses.
1623  * MSI MS-171F
1624  * https://bugzilla.kernel.org/show_bug.cgi?id=12461
1625  */
1626 static int ec_correct_ecdt(const struct dmi_system_id *id)
1627 {
1628         pr_debug("Detected system needing ECDT address correction.\n");
1629         EC_FLAGS_CORRECT_ECDT = 1;
1630         return 0;
1631 }
1632
1633 static struct dmi_system_id ec_dmi_table[] __initdata = {
1634         {
1635         ec_correct_ecdt, "MSI MS-171F", {
1636         DMI_MATCH(DMI_SYS_VENDOR, "Micro-Star"),
1637         DMI_MATCH(DMI_PRODUCT_NAME, "MS-171F"),}, NULL},
1638         {
1639         ec_clear_on_resume, "Samsung hardware", {
1640         DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD.")}, NULL},
1641         {},
1642 };
1643
1644 int __init acpi_ec_ecdt_probe(void)
1645 {
1646         int ret;
1647         acpi_status status;
1648         struct acpi_table_ecdt *ecdt_ptr;
1649         struct acpi_ec *ec;
1650
1651         ec = acpi_ec_alloc();
1652         if (!ec)
1653                 return -ENOMEM;
1654         /*
1655          * Generate a boot ec context
1656          */
1657         dmi_check_system(ec_dmi_table);
1658         status = acpi_get_table(ACPI_SIG_ECDT, 1,
1659                                 (struct acpi_table_header **)&ecdt_ptr);
1660         if (ACPI_FAILURE(status)) {
1661                 ret = -ENODEV;
1662                 goto error;
1663         }
1664
1665         if (!ecdt_ptr->control.address || !ecdt_ptr->data.address) {
1666                 /*
1667                  * Asus X50GL:
1668                  * https://bugzilla.kernel.org/show_bug.cgi?id=11880
1669                  */
1670                 ret = -ENODEV;
1671                 goto error;
1672         }
1673
1674         pr_info("EC description table is found, configuring boot EC\n");
1675         if (EC_FLAGS_CORRECT_ECDT) {
1676                 ec->command_addr = ecdt_ptr->data.address;
1677                 ec->data_addr = ecdt_ptr->control.address;
1678         } else {
1679                 ec->command_addr = ecdt_ptr->control.address;
1680                 ec->data_addr = ecdt_ptr->data.address;
1681         }
1682         ec->gpe = ecdt_ptr->gpe;
1683         ec->handle = ACPI_ROOT_OBJECT;
1684         ret = ec_install_handlers(ec);
1685 error:
1686         if (ret)
1687                 kfree(ec);
1688         else
1689                 first_ec = boot_ec = ec;
1690         return ret;
1691 }
1692
1693 #ifdef CONFIG_PM_SLEEP
1694 static void acpi_ec_enter_noirq(struct acpi_ec *ec)
1695 {
1696         unsigned long flags;
1697
1698         if (ec == first_ec) {
1699                 spin_lock_irqsave(&ec->lock, flags);
1700                 ec->saved_busy_polling = ec_busy_polling;
1701                 ec->saved_polling_guard = ec_polling_guard;
1702                 ec_busy_polling = true;
1703                 ec_polling_guard = 0;
1704                 ec_log_drv("interrupt blocked");
1705                 spin_unlock_irqrestore(&ec->lock, flags);
1706         }
1707 }
1708
1709 static void acpi_ec_leave_noirq(struct acpi_ec *ec)
1710 {
1711         unsigned long flags;
1712
1713         if (ec == first_ec) {
1714                 spin_lock_irqsave(&ec->lock, flags);
1715                 ec_busy_polling = ec->saved_busy_polling;
1716                 ec_polling_guard = ec->saved_polling_guard;
1717                 ec_log_drv("interrupt unblocked");
1718                 spin_unlock_irqrestore(&ec->lock, flags);
1719         }
1720 }
1721
1722 static int acpi_ec_suspend_noirq(struct device *dev)
1723 {
1724         struct acpi_ec *ec =
1725                 acpi_driver_data(to_acpi_device(dev));
1726
1727         acpi_ec_enter_noirq(ec);
1728         return 0;
1729 }
1730
1731 static int acpi_ec_resume_noirq(struct device *dev)
1732 {
1733         struct acpi_ec *ec =
1734                 acpi_driver_data(to_acpi_device(dev));
1735
1736         acpi_ec_leave_noirq(ec);
1737         return 0;
1738 }
1739
1740 static int acpi_ec_suspend(struct device *dev)
1741 {
1742         struct acpi_ec *ec =
1743                 acpi_driver_data(to_acpi_device(dev));
1744
1745         if (ec_freeze_events)
1746                 acpi_ec_disable_event(ec);
1747         return 0;
1748 }
1749
1750 static int acpi_ec_resume(struct device *dev)
1751 {
1752         struct acpi_ec *ec =
1753                 acpi_driver_data(to_acpi_device(dev));
1754
1755         acpi_ec_enable_event(ec);
1756         return 0;
1757 }
1758 #endif
1759
1760 static const struct dev_pm_ops acpi_ec_pm = {
1761         SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(acpi_ec_suspend_noirq, acpi_ec_resume_noirq)
1762         SET_SYSTEM_SLEEP_PM_OPS(acpi_ec_suspend, acpi_ec_resume)
1763 };
1764
1765 static int param_set_event_clearing(const char *val, struct kernel_param *kp)
1766 {
1767         int result = 0;
1768
1769         if (!strncmp(val, "status", sizeof("status") - 1)) {
1770                 ec_event_clearing = ACPI_EC_EVT_TIMING_STATUS;
1771                 pr_info("Assuming SCI_EVT clearing on EC_SC accesses\n");
1772         } else if (!strncmp(val, "query", sizeof("query") - 1)) {
1773                 ec_event_clearing = ACPI_EC_EVT_TIMING_QUERY;
1774                 pr_info("Assuming SCI_EVT clearing on QR_EC writes\n");
1775         } else if (!strncmp(val, "event", sizeof("event") - 1)) {
1776                 ec_event_clearing = ACPI_EC_EVT_TIMING_EVENT;
1777                 pr_info("Assuming SCI_EVT clearing on event reads\n");
1778         } else
1779                 result = -EINVAL;
1780         return result;
1781 }
1782
1783 static int param_get_event_clearing(char *buffer, struct kernel_param *kp)
1784 {
1785         switch (ec_event_clearing) {
1786         case ACPI_EC_EVT_TIMING_STATUS:
1787                 return sprintf(buffer, "status");
1788         case ACPI_EC_EVT_TIMING_QUERY:
1789                 return sprintf(buffer, "query");
1790         case ACPI_EC_EVT_TIMING_EVENT:
1791                 return sprintf(buffer, "event");
1792         default:
1793                 return sprintf(buffer, "invalid");
1794         }
1795         return 0;
1796 }
1797
1798 module_param_call(ec_event_clearing, param_set_event_clearing, param_get_event_clearing,
1799                   NULL, 0644);
1800 MODULE_PARM_DESC(ec_event_clearing, "Assumed SCI_EVT clearing timing");
1801
1802 static struct acpi_driver acpi_ec_driver = {
1803         .name = "ec",
1804         .class = ACPI_EC_CLASS,
1805         .ids = ec_device_ids,
1806         .ops = {
1807                 .add = acpi_ec_add,
1808                 .remove = acpi_ec_remove,
1809                 },
1810         .drv.pm = &acpi_ec_pm,
1811 };
1812
1813 static inline int acpi_ec_query_init(void)
1814 {
1815         if (!ec_query_wq) {
1816                 ec_query_wq = alloc_workqueue("kec_query", 0,
1817                                               ec_max_queries);
1818                 if (!ec_query_wq)
1819                         return -ENODEV;
1820         }
1821         return 0;
1822 }
1823
1824 static inline void acpi_ec_query_exit(void)
1825 {
1826         if (ec_query_wq) {
1827                 destroy_workqueue(ec_query_wq);
1828                 ec_query_wq = NULL;
1829         }
1830 }
1831
1832 int __init acpi_ec_init(void)
1833 {
1834         int result;
1835
1836         /* register workqueue for _Qxx evaluations */
1837         result = acpi_ec_query_init();
1838         if (result)
1839                 goto err_exit;
1840         /* Now register the driver for the EC */
1841         result = acpi_bus_register_driver(&acpi_ec_driver);
1842         if (result)
1843                 goto err_exit;
1844
1845 err_exit:
1846         if (result)
1847                 acpi_ec_query_exit();
1848         return result;
1849 }
1850
1851 /* EC driver currently not unloadable */
1852 #if 0
1853 static void __exit acpi_ec_exit(void)
1854 {
1855
1856         acpi_bus_unregister_driver(&acpi_ec_driver);
1857         acpi_ec_query_exit();
1858 }
1859 #endif  /* 0 */