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 bool boot_ec_is_ecdt = false;
 188 static struct workqueue_struct *ec_query_wq;
 189
 190 static int EC_FLAGS_CLEAR_ON_RESUME; /* Needs acpi_ec_clear() on boot/resume */
 191 static int EC_FLAGS_QUERY_HANDSHAKE; /* Needs QR_EC issued when SCI_EVT set */
 192 static int EC_FLAGS_CORRECT_ECDT; /* Needs ECDT port address correction */
 193
 194 /* --------------------------------------------------------------------------
 195  *                           Logging/Debugging
 196  * -------------------------------------------------------------------------- */
 197
 198 /*
 199  * Splitters used by the developers to track the boundary of the EC
 200  * handling processes.
 201  */
 202 #ifdef DEBUG
 203 #define EC_DBG_SEP      " "
 204 #define EC_DBG_DRV      "+++++"
 205 #define EC_DBG_STM      "====="
 206 #define EC_DBG_REQ      "*****"
 207 #define EC_DBG_EVT      "#####"
 208 #else
 209 #define EC_DBG_SEP      ""
 210 #define EC_DBG_DRV
 211 #define EC_DBG_STM
 212 #define EC_DBG_REQ
 213 #define EC_DBG_EVT
 214 #endif
 215
 216 #define ec_log_raw(fmt, ...) \
 217         pr_info(fmt "\n", ##__VA_ARGS__)
 218 #define ec_dbg_raw(fmt, ...) \
 219         pr_debug(fmt "\n", ##__VA_ARGS__)
 220 #define ec_log(filter, fmt, ...) \
 221         ec_log_raw(filter EC_DBG_SEP fmt EC_DBG_SEP filter, ##__VA_ARGS__)
 222 #define ec_dbg(filter, fmt, ...) \
 223         ec_dbg_raw(filter EC_DBG_SEP fmt EC_DBG_SEP filter, ##__VA_ARGS__)
 224
 225 #define ec_log_drv(fmt, ...) \
 226         ec_log(EC_DBG_DRV, fmt, ##__VA_ARGS__)
 227 #define ec_dbg_drv(fmt, ...) \
 228         ec_dbg(EC_DBG_DRV, fmt, ##__VA_ARGS__)
 229 #define ec_dbg_stm(fmt, ...) \
 230         ec_dbg(EC_DBG_STM, fmt, ##__VA_ARGS__)
 231 #define ec_dbg_req(fmt, ...) \
 232         ec_dbg(EC_DBG_REQ, fmt, ##__VA_ARGS__)
 233 #define ec_dbg_evt(fmt, ...) \
 234         ec_dbg(EC_DBG_EVT, fmt, ##__VA_ARGS__)
 235 #define ec_dbg_ref(ec, fmt, ...) \
 236         ec_dbg_raw("%lu: " fmt, ec->reference_count, ## __VA_ARGS__)
 237
 238 /* --------------------------------------------------------------------------
 239  *                           Device Flags
 240  * -------------------------------------------------------------------------- */
 241
 242 static bool acpi_ec_started(struct acpi_ec *ec)
 243 {
 244         return test_bit(EC_FLAGS_STARTED, &ec->flags) &&
 245                !test_bit(EC_FLAGS_STOPPED, &ec->flags);
 246 }
 247
 248 static bool acpi_ec_event_enabled(struct acpi_ec *ec)
 249 {
 250         /*
 251          * There is an OSPM early stage logic. During the early stages
 252          * (boot/resume), OSPMs shouldn't enable the event handling, only
 253          * the EC transactions are allowed to be performed.
 254          */
 255         if (!test_bit(EC_FLAGS_QUERY_ENABLED, &ec->flags))
 256                 return false;
 257         /*
 258          * However, disabling the event handling is experimental for late
 259          * stage (suspend), and is controlled by the boot parameter of
 260          * "ec_freeze_events":
 261          * 1. true:  The EC event handling is disabled before entering
 262          *           the noirq stage.
 263          * 2. false: The EC event handling is automatically disabled as
 264          *           soon as the EC driver is stopped.
 265          */
 266         if (ec_freeze_events)
 267                 return acpi_ec_started(ec);
 268         else
 269                 return test_bit(EC_FLAGS_STARTED, &ec->flags);
 270 }
 271
 272 static bool acpi_ec_flushed(struct acpi_ec *ec)
 273 {
 274         return ec->reference_count == 1;
 275 }
 276
 277 /* --------------------------------------------------------------------------
 278  *                           EC Registers
 279  * -------------------------------------------------------------------------- */
 280
 281 static inline u8 acpi_ec_read_status(struct acpi_ec *ec)
 282 {
 283         u8 x = inb(ec->command_addr);
 284
 285         ec_dbg_raw("EC_SC(R) = 0x%2.2x "
 286                    "SCI_EVT=%d BURST=%d CMD=%d IBF=%d OBF=%d",
 287                    x,
 288                    !!(x & ACPI_EC_FLAG_SCI),
 289                    !!(x & ACPI_EC_FLAG_BURST),
 290                    !!(x & ACPI_EC_FLAG_CMD),
 291                    !!(x & ACPI_EC_FLAG_IBF),
 292                    !!(x & ACPI_EC_FLAG_OBF));
 293         return x;
 294 }
 295
 296 static inline u8 acpi_ec_read_data(struct acpi_ec *ec)
 297 {
 298         u8 x = inb(ec->data_addr);
 299
 300         ec->timestamp = jiffies;
 301         ec_dbg_raw("EC_DATA(R) = 0x%2.2x", x);
 302         return x;
 303 }
 304
 305 static inline void acpi_ec_write_cmd(struct acpi_ec *ec, u8 command)
 306 {
 307         ec_dbg_raw("EC_SC(W) = 0x%2.2x", command);
 308         outb(command, ec->command_addr);
 309         ec->timestamp = jiffies;
 310 }
 311
 312 static inline void acpi_ec_write_data(struct acpi_ec *ec, u8 data)
 313 {
 314         ec_dbg_raw("EC_DATA(W) = 0x%2.2x", data);
 315         outb(data, ec->data_addr);
 316         ec->timestamp = jiffies;
 317 }
 318
 319 #ifdef DEBUG
 320 static const char *acpi_ec_cmd_string(u8 cmd)
 321 {
 322         switch (cmd) {
 323         case 0x80:
 324                 return "RD_EC";
 325         case 0x81:
 326                 return "WR_EC";
 327         case 0x82:
 328                 return "BE_EC";
 329         case 0x83:
 330                 return "BD_EC";
 331         case 0x84:
 332                 return "QR_EC";
 333         }
 334         return "UNKNOWN";
 335 }
 336 #else
 337 #define acpi_ec_cmd_string(cmd)         "UNDEF"
 338 #endif
 339
 340 /* --------------------------------------------------------------------------
 341  *                           GPE Registers
 342  * -------------------------------------------------------------------------- */
 343
 344 static inline bool acpi_ec_is_gpe_raised(struct acpi_ec *ec)
 345 {
 346         acpi_event_status gpe_status = 0;
 347
 348         (void)acpi_get_gpe_status(NULL, ec->gpe, &gpe_status);
 349         return (gpe_status & ACPI_EVENT_FLAG_STATUS_SET) ? true : false;
 350 }
 351
 352 static inline void acpi_ec_enable_gpe(struct acpi_ec *ec, bool open)
 353 {
 354         if (open)
 355                 acpi_enable_gpe(NULL, ec->gpe);
 356         else {
 357                 BUG_ON(ec->reference_count < 1);
 358                 acpi_set_gpe(NULL, ec->gpe, ACPI_GPE_ENABLE);
 359         }
 360         if (acpi_ec_is_gpe_raised(ec)) {
 361                 /*
 362                  * On some platforms, EN=1 writes cannot trigger GPE. So
 363                  * software need to manually trigger a pseudo GPE event on
 364                  * EN=1 writes.
 365                  */
 366                 ec_dbg_raw("Polling quirk");
 367                 advance_transaction(ec);
 368         }
 369 }
 370
 371 static inline void acpi_ec_disable_gpe(struct acpi_ec *ec, bool close)
 372 {
 373         if (close)
 374                 acpi_disable_gpe(NULL, ec->gpe);
 375         else {
 376                 BUG_ON(ec->reference_count < 1);
 377                 acpi_set_gpe(NULL, ec->gpe, ACPI_GPE_DISABLE);
 378         }
 379 }
 380
 381 static inline void acpi_ec_clear_gpe(struct acpi_ec *ec)
 382 {
 383         /*
 384          * GPE STS is a W1C register, which means:
 385          * 1. Software can clear it without worrying about clearing other
 386          *    GPEs' STS bits when the hardware sets them in parallel.
 387          * 2. As long as software can ensure only clearing it when it is
 388          *    set, hardware won't set it in parallel.
 389          * So software can clear GPE in any contexts.
 390          * Warning: do not move the check into advance_transaction() as the
 391          * EC commands will be sent without GPE raised.
 392          */
 393         if (!acpi_ec_is_gpe_raised(ec))
 394                 return;
 395         acpi_clear_gpe(NULL, ec->gpe);
 396 }
 397
 398 /* --------------------------------------------------------------------------
 399  *                           Transaction Management
 400  * -------------------------------------------------------------------------- */
 401
 402 static void acpi_ec_submit_request(struct acpi_ec *ec)
 403 {
 404         ec->reference_count++;
 405         if (test_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags) &&
 406             ec->reference_count == 1)
 407                 acpi_ec_enable_gpe(ec, true);
 408 }
 409
 410 static void acpi_ec_complete_request(struct acpi_ec *ec)
 411 {
 412         bool flushed = false;
 413
 414         ec->reference_count--;
 415         if (test_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags) &&
 416             ec->reference_count == 0)
 417                 acpi_ec_disable_gpe(ec, true);
 418         flushed = acpi_ec_flushed(ec);
 419         if (flushed)
 420                 wake_up(&ec->wait);
 421 }
 422
 423 static void acpi_ec_set_storm(struct acpi_ec *ec, u8 flag)
 424 {
 425         if (!test_bit(flag, &ec->flags)) {
 426                 acpi_ec_disable_gpe(ec, false);
 427                 ec_dbg_drv("Polling enabled");
 428                 set_bit(flag, &ec->flags);
 429         }
 430 }
 431
 432 static void acpi_ec_clear_storm(struct acpi_ec *ec, u8 flag)
 433 {
 434         if (test_bit(flag, &ec->flags)) {
 435                 clear_bit(flag, &ec->flags);
 436                 acpi_ec_enable_gpe(ec, false);
 437                 ec_dbg_drv("Polling disabled");
 438         }
 439 }
 440
 441 /*
 442  * acpi_ec_submit_flushable_request() - Increase the reference count unless
 443  *                                      the flush operation is not in
 444  *                                      progress
 445  * @ec: the EC device
 446  *
 447  * This function must be used before taking a new action that should hold
 448  * the reference count.  If this function returns false, then the action
 449  * must be discarded or it will prevent the flush operation from being
 450  * completed.
 451  */
 452 static bool acpi_ec_submit_flushable_request(struct acpi_ec *ec)
 453 {
 454         if (!acpi_ec_started(ec))
 455                 return false;
 456         acpi_ec_submit_request(ec);
 457         return true;
 458 }
 459
 460 static void acpi_ec_submit_query(struct acpi_ec *ec)
 461 {
 462         if (acpi_ec_event_enabled(ec) &&
 463             !test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags)) {
 464                 ec_dbg_evt("Command(%s) submitted/blocked",
 465                            acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
 466                 ec->nr_pending_queries++;
 467                 schedule_work(&ec->work);
 468         }
 469 }
 470
 471 static void acpi_ec_complete_query(struct acpi_ec *ec)
 472 {
 473         if (test_bit(EC_FLAGS_QUERY_PENDING, &ec->flags)) {
 474                 clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
 475                 ec_dbg_evt("Command(%s) unblocked",
 476                            acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
 477         }
 478 }
 479
 480 static inline void __acpi_ec_enable_event(struct acpi_ec *ec)
 481 {
 482         if (!test_and_set_bit(EC_FLAGS_QUERY_ENABLED, &ec->flags))
 483                 ec_log_drv("event unblocked");
 484         if (!test_bit(EC_FLAGS_QUERY_PENDING, &ec->flags))
 485                 advance_transaction(ec);
 486 }
 487
 488 static inline void __acpi_ec_disable_event(struct acpi_ec *ec)
 489 {
 490         if (test_and_clear_bit(EC_FLAGS_QUERY_ENABLED, &ec->flags))
 491                 ec_log_drv("event blocked");
 492 }
 493
 494 /*
 495  * Process _Q events that might have accumulated in the EC.
 496  * Run with locked ec mutex.
 497  */
 498 static void acpi_ec_clear(struct acpi_ec *ec)
 499 {
 500         int i, status;
 501         u8 value = 0;
 502
 503         for (i = 0; i < ACPI_EC_CLEAR_MAX; i++) {
 504                 status = acpi_ec_query(ec, &value);
 505                 if (status || !value)
 506                         break;
 507         }
 508         if (unlikely(i == ACPI_EC_CLEAR_MAX))
 509                 pr_warn("Warning: Maximum of %d stale EC events cleared\n", i);
 510         else
 511                 pr_info("%d stale EC events cleared\n", i);
 512 }
 513
 514 static void acpi_ec_enable_event(struct acpi_ec *ec)
 515 {
 516         unsigned long flags;
 517
 518         spin_lock_irqsave(&ec->lock, flags);
 519         if (acpi_ec_started(ec))
 520                 __acpi_ec_enable_event(ec);
 521         spin_unlock_irqrestore(&ec->lock, flags);
 522
 523         /* Drain additional events if hardware requires that */
 524         if (EC_FLAGS_CLEAR_ON_RESUME)
 525                 acpi_ec_clear(ec);
 526 }
 527
 528 static bool acpi_ec_query_flushed(struct acpi_ec *ec)
 529 {
 530         bool flushed;
 531         unsigned long flags;
 532
 533         spin_lock_irqsave(&ec->lock, flags);
 534         flushed = !ec->nr_pending_queries;
 535         spin_unlock_irqrestore(&ec->lock, flags);
 536         return flushed;
 537 }
 538
 539 static void __acpi_ec_flush_event(struct acpi_ec *ec)
 540 {
 541         /*
 542          * When ec_freeze_events is true, we need to flush events in
 543          * the proper position before entering the noirq stage.
 544          */
 545         wait_event(ec->wait, acpi_ec_query_flushed(ec));
 546         if (ec_query_wq)
 547                 flush_workqueue(ec_query_wq);
 548 }
 549
 550 static void acpi_ec_disable_event(struct acpi_ec *ec)
 551 {
 552         unsigned long flags;
 553
 554         spin_lock_irqsave(&ec->lock, flags);
 555         __acpi_ec_disable_event(ec);
 556         spin_unlock_irqrestore(&ec->lock, flags);
 557         __acpi_ec_flush_event(ec);
 558 }
 559
 560 static bool acpi_ec_guard_event(struct acpi_ec *ec)
 561 {
 562         bool guarded = true;
 563         unsigned long flags;
 564
 565         spin_lock_irqsave(&ec->lock, flags);
 566         /*
 567          * If firmware SCI_EVT clearing timing is "event", we actually
 568          * don't know when the SCI_EVT will be cleared by firmware after
 569          * evaluating _Qxx, so we need to re-check SCI_EVT after waiting an
 570          * acceptable period.
 571          *
 572          * The guarding period begins when EC_FLAGS_QUERY_PENDING is
 573          * flagged, which means SCI_EVT check has just been performed.
 574          * But if the current transaction is ACPI_EC_COMMAND_QUERY, the
 575          * guarding should have already been performed (via
 576          * EC_FLAGS_QUERY_GUARDING) and should not be applied so that the
 577          * ACPI_EC_COMMAND_QUERY transaction can be transitioned into
 578          * ACPI_EC_COMMAND_POLL state immediately.
 579          */
 580         if (ec_event_clearing == ACPI_EC_EVT_TIMING_STATUS ||
 581             ec_event_clearing == ACPI_EC_EVT_TIMING_QUERY ||
 582             !test_bit(EC_FLAGS_QUERY_PENDING, &ec->flags) ||
 583             (ec->curr && ec->curr->command == ACPI_EC_COMMAND_QUERY))
 584                 guarded = false;
 585         spin_unlock_irqrestore(&ec->lock, flags);
 586         return guarded;
 587 }
 588
 589 static int ec_transaction_polled(struct acpi_ec *ec)
 590 {
 591         unsigned long flags;
 592         int ret = 0;
 593
 594         spin_lock_irqsave(&ec->lock, flags);
 595         if (ec->curr && (ec->curr->flags & ACPI_EC_COMMAND_POLL))
 596                 ret = 1;
 597         spin_unlock_irqrestore(&ec->lock, flags);
 598         return ret;
 599 }
 600
 601 static int ec_transaction_completed(struct acpi_ec *ec)
 602 {
 603         unsigned long flags;
 604         int ret = 0;
 605
 606         spin_lock_irqsave(&ec->lock, flags);
 607         if (ec->curr && (ec->curr->flags & ACPI_EC_COMMAND_COMPLETE))
 608                 ret = 1;
 609         spin_unlock_irqrestore(&ec->lock, flags);
 610         return ret;
 611 }
 612
 613 static inline void ec_transaction_transition(struct acpi_ec *ec, unsigned long flag)
 614 {
 615         ec->curr->flags |= flag;
 616         if (ec->curr->command == ACPI_EC_COMMAND_QUERY) {
 617                 if (ec_event_clearing == ACPI_EC_EVT_TIMING_STATUS &&
 618                     flag == ACPI_EC_COMMAND_POLL)
 619                         acpi_ec_complete_query(ec);
 620                 if (ec_event_clearing == ACPI_EC_EVT_TIMING_QUERY &&
 621                     flag == ACPI_EC_COMMAND_COMPLETE)
 622                         acpi_ec_complete_query(ec);
 623                 if (ec_event_clearing == ACPI_EC_EVT_TIMING_EVENT &&
 624                     flag == ACPI_EC_COMMAND_COMPLETE)
 625                         set_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags);
 626         }
 627 }
 628
 629 static void advance_transaction(struct acpi_ec *ec)
 630 {
 631         struct transaction *t;
 632         u8 status;
 633         bool wakeup = false;
 634
 635         ec_dbg_stm("%s (%d)", in_interrupt() ? "IRQ" : "TASK",
 636                    smp_processor_id());
 637         /*
 638          * By always clearing STS before handling all indications, we can
 639          * ensure a hardware STS 0->1 change after this clearing can always
 640          * trigger a GPE interrupt.
 641          */
 642         acpi_ec_clear_gpe(ec);
 643         status = acpi_ec_read_status(ec);
 644         t = ec->curr;
 645         /*
 646          * Another IRQ or a guarded polling mode advancement is detected,
 647          * the next QR_EC submission is then allowed.
 648          */
 649         if (!t || !(t->flags & ACPI_EC_COMMAND_POLL)) {
 650                 if (ec_event_clearing == ACPI_EC_EVT_TIMING_EVENT &&
 651                     (!ec->nr_pending_queries ||
 652                      test_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags))) {
 653                         clear_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags);
 654                         acpi_ec_complete_query(ec);
 655                 }
 656         }
 657         if (!t)
 658                 goto err;
 659         if (t->flags & ACPI_EC_COMMAND_POLL) {
 660                 if (t->wlen > t->wi) {
 661                         if ((status & ACPI_EC_FLAG_IBF) == 0)
 662                                 acpi_ec_write_data(ec, t->wdata[t->wi++]);
 663                         else
 664                                 goto err;
 665                 } else if (t->rlen > t->ri) {
 666                         if ((status & ACPI_EC_FLAG_OBF) == 1) {
 667                                 t->rdata[t->ri++] = acpi_ec_read_data(ec);
 668                                 if (t->rlen == t->ri) {
 669                                         ec_transaction_transition(ec, ACPI_EC_COMMAND_COMPLETE);
 670                                         if (t->command == ACPI_EC_COMMAND_QUERY)
 671                                                 ec_dbg_evt("Command(%s) completed by hardware",
 672                                                            acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
 673                                         wakeup = true;
 674                                 }
 675                         } else
 676                                 goto err;
 677                 } else if (t->wlen == t->wi &&
 678                            (status & ACPI_EC_FLAG_IBF) == 0) {
 679                         ec_transaction_transition(ec, ACPI_EC_COMMAND_COMPLETE);
 680                         wakeup = true;
 681                 }
 682                 goto out;
 683         } else {
 684                 if (EC_FLAGS_QUERY_HANDSHAKE &&
 685                     !(status & ACPI_EC_FLAG_SCI) &&
 686                     (t->command == ACPI_EC_COMMAND_QUERY)) {
 687                         ec_transaction_transition(ec, ACPI_EC_COMMAND_POLL);
 688                         t->rdata[t->ri++] = 0x00;
 689                         ec_transaction_transition(ec, ACPI_EC_COMMAND_COMPLETE);
 690                         ec_dbg_evt("Command(%s) completed by software",
 691                                    acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
 692                         wakeup = true;
 693                 } else if ((status & ACPI_EC_FLAG_IBF) == 0) {
 694                         acpi_ec_write_cmd(ec, t->command);
 695                         ec_transaction_transition(ec, ACPI_EC_COMMAND_POLL);
 696                 } else
 697                         goto err;
 698                 goto out;
 699         }
 700 err:
 701         /*
 702          * If SCI bit is set, then don't think it's a false IRQ
 703          * otherwise will take a not handled IRQ as a false one.
 704          */
 705         if (!(status & ACPI_EC_FLAG_SCI)) {
 706                 if (in_interrupt() && t) {
 707                         if (t->irq_count < ec_storm_threshold)
 708                                 ++t->irq_count;
 709                         /* Allow triggering on 0 threshold */
 710                         if (t->irq_count == ec_storm_threshold)
 711                                 acpi_ec_set_storm(ec, EC_FLAGS_COMMAND_STORM);
 712                 }
 713         }
 714 out:
 715         if (status & ACPI_EC_FLAG_SCI)
 716                 acpi_ec_submit_query(ec);
 717         if (wakeup && in_interrupt())
 718                 wake_up(&ec->wait);
 719 }
 720
 721 static void start_transaction(struct acpi_ec *ec)
 722 {
 723         ec->curr->irq_count = ec->curr->wi = ec->curr->ri = 0;
 724         ec->curr->flags = 0;
 725 }
 726
 727 static int ec_guard(struct acpi_ec *ec)
 728 {
 729         unsigned long guard = usecs_to_jiffies(ec_polling_guard);
 730         unsigned long timeout = ec->timestamp + guard;
 731
 732         /* Ensure guarding period before polling EC status */
 733         do {
 734                 if (ec_busy_polling) {
 735                         /* Perform busy polling */
 736                         if (ec_transaction_completed(ec))
 737                                 return 0;
 738                         udelay(jiffies_to_usecs(guard));
 739                 } else {
 740                         /*
 741                          * Perform wait polling
 742                          * 1. Wait the transaction to be completed by the
 743                          *    GPE handler after the transaction enters
 744                          *    ACPI_EC_COMMAND_POLL state.
 745                          * 2. A special guarding logic is also required
 746                          *    for event clearing mode "event" before the
 747                          *    transaction enters ACPI_EC_COMMAND_POLL
 748                          *    state.
 749                          */
 750                         if (!ec_transaction_polled(ec) &&
 751                             !acpi_ec_guard_event(ec))
 752                                 break;
 753                         if (wait_event_timeout(ec->wait,
 754                                                ec_transaction_completed(ec),
 755                                                guard))
 756                                 return 0;
 757                 }
 758         } while (time_before(jiffies, timeout));
 759         return -ETIME;
 760 }
 761
 762 static int ec_poll(struct acpi_ec *ec)
 763 {
 764         unsigned long flags;
 765         int repeat = 5; /* number of command restarts */
 766
 767         while (repeat--) {
 768                 unsigned long delay = jiffies +
 769                         msecs_to_jiffies(ec_delay);
 770                 do {
 771                         if (!ec_guard(ec))
 772                                 return 0;
 773                         spin_lock_irqsave(&ec->lock, flags);
 774                         advance_transaction(ec);
 775                         spin_unlock_irqrestore(&ec->lock, flags);
 776                 } while (time_before(jiffies, delay));
 777                 pr_debug("controller reset, restart transaction\n");
 778                 spin_lock_irqsave(&ec->lock, flags);
 779                 start_transaction(ec);
 780                 spin_unlock_irqrestore(&ec->lock, flags);
 781         }
 782         return -ETIME;
 783 }
 784
 785 static int acpi_ec_transaction_unlocked(struct acpi_ec *ec,
 786                                         struct transaction *t)
 787 {
 788         unsigned long tmp;
 789         int ret = 0;
 790
 791         /* start transaction */
 792         spin_lock_irqsave(&ec->lock, tmp);
 793         /* Enable GPE for command processing (IBF=0/OBF=1) */
 794         if (!acpi_ec_submit_flushable_request(ec)) {
 795                 ret = -EINVAL;
 796                 goto unlock;
 797         }
 798         ec_dbg_ref(ec, "Increase command");
 799         /* following two actions should be kept atomic */
 800         ec->curr = t;
 801         ec_dbg_req("Command(%s) started", acpi_ec_cmd_string(t->command));
 802         start_transaction(ec);
 803         spin_unlock_irqrestore(&ec->lock, tmp);
 804
 805         ret = ec_poll(ec);
 806
 807         spin_lock_irqsave(&ec->lock, tmp);
 808         if (t->irq_count == ec_storm_threshold)
 809                 acpi_ec_clear_storm(ec, EC_FLAGS_COMMAND_STORM);
 810         ec_dbg_req("Command(%s) stopped", acpi_ec_cmd_string(t->command));
 811         ec->curr = NULL;
 812         /* Disable GPE for command processing (IBF=0/OBF=1) */
 813         acpi_ec_complete_request(ec);
 814         ec_dbg_ref(ec, "Decrease command");
 815 unlock:
 816         spin_unlock_irqrestore(&ec->lock, tmp);
 817         return ret;
 818 }
 819
 820 static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t)
 821 {
 822         int status;
 823         u32 glk;
 824
 825         if (!ec || (!t) || (t->wlen && !t->wdata) || (t->rlen && !t->rdata))
 826                 return -EINVAL;
 827         if (t->rdata)
 828                 memset(t->rdata, 0, t->rlen);
 829
 830         mutex_lock(&ec->mutex);
 831         if (ec->global_lock) {
 832                 status = acpi_acquire_global_lock(ACPI_EC_UDELAY_GLK, &glk);
 833                 if (ACPI_FAILURE(status)) {
 834                         status = -ENODEV;
 835                         goto unlock;
 836                 }
 837         }
 838
 839         status = acpi_ec_transaction_unlocked(ec, t);
 840
 841         if (ec->global_lock)
 842                 acpi_release_global_lock(glk);
 843 unlock:
 844         mutex_unlock(&ec->mutex);
 845         return status;
 846 }
 847
 848 static int acpi_ec_burst_enable(struct acpi_ec *ec)
 849 {
 850         u8 d;
 851         struct transaction t = {.command = ACPI_EC_BURST_ENABLE,
 852                                 .wdata = NULL, .rdata = &d,
 853                                 .wlen = 0, .rlen = 1};
 854
 855         return acpi_ec_transaction(ec, &t);
 856 }
 857
 858 static int acpi_ec_burst_disable(struct acpi_ec *ec)
 859 {
 860         struct transaction t = {.command = ACPI_EC_BURST_DISABLE,
 861                                 .wdata = NULL, .rdata = NULL,
 862                                 .wlen = 0, .rlen = 0};
 863
 864         return (acpi_ec_read_status(ec) & ACPI_EC_FLAG_BURST) ?
 865                                 acpi_ec_transaction(ec, &t) : 0;
 866 }
 867
 868 static int acpi_ec_read(struct acpi_ec *ec, u8 address, u8 *data)
 869 {
 870         int result;
 871         u8 d;
 872         struct transaction t = {.command = ACPI_EC_COMMAND_READ,
 873                                 .wdata = &address, .rdata = &d,
 874                                 .wlen = 1, .rlen = 1};
 875
 876         result = acpi_ec_transaction(ec, &t);
 877         *data = d;
 878         return result;
 879 }
 880
 881 static int acpi_ec_write(struct acpi_ec *ec, u8 address, u8 data)
 882 {
 883         u8 wdata[2] = { address, data };
 884         struct transaction t = {.command = ACPI_EC_COMMAND_WRITE,
 885                                 .wdata = wdata, .rdata = NULL,
 886                                 .wlen = 2, .rlen = 0};
 887
 888         return acpi_ec_transaction(ec, &t);
 889 }
 890
 891 int ec_read(u8 addr, u8 *val)
 892 {
 893         int err;
 894         u8 temp_data;
 895
 896         if (!first_ec)
 897                 return -ENODEV;
 898
 899         err = acpi_ec_read(first_ec, addr, &temp_data);
 900
 901         if (!err) {
 902                 *val = temp_data;
 903                 return 0;
 904         }
 905         return err;
 906 }
 907 EXPORT_SYMBOL(ec_read);
 908
 909 int ec_write(u8 addr, u8 val)
 910 {
 911         int err;
 912
 913         if (!first_ec)
 914                 return -ENODEV;
 915
 916         err = acpi_ec_write(first_ec, addr, val);
 917
 918         return err;
 919 }
 920 EXPORT_SYMBOL(ec_write);
 921
 922 int ec_transaction(u8 command,
 923                    const u8 *wdata, unsigned wdata_len,
 924                    u8 *rdata, unsigned rdata_len)
 925 {
 926         struct transaction t = {.command = command,
 927                                 .wdata = wdata, .rdata = rdata,
 928                                 .wlen = wdata_len, .rlen = rdata_len};
 929
 930         if (!first_ec)
 931                 return -ENODEV;
 932
 933         return acpi_ec_transaction(first_ec, &t);
 934 }
 935 EXPORT_SYMBOL(ec_transaction);
 936
 937 /* Get the handle to the EC device */
 938 acpi_handle ec_get_handle(void)
 939 {
 940         if (!first_ec)
 941                 return NULL;
 942         return first_ec->handle;
 943 }
 944 EXPORT_SYMBOL(ec_get_handle);
 945
 946 static void acpi_ec_start(struct acpi_ec *ec, bool resuming)
 947 {
 948         unsigned long flags;
 949
 950         spin_lock_irqsave(&ec->lock, flags);
 951         if (!test_and_set_bit(EC_FLAGS_STARTED, &ec->flags)) {
 952                 ec_dbg_drv("Starting EC");
 953                 /* Enable GPE for event processing (SCI_EVT=1) */
 954                 if (!resuming) {
 955                         acpi_ec_submit_request(ec);
 956                         ec_dbg_ref(ec, "Increase driver");
 957                 }
 958                 ec_log_drv("EC started");
 959         }
 960         spin_unlock_irqrestore(&ec->lock, flags);
 961 }
 962
 963 static bool acpi_ec_stopped(struct acpi_ec *ec)
 964 {
 965         unsigned long flags;
 966         bool flushed;
 967
 968         spin_lock_irqsave(&ec->lock, flags);
 969         flushed = acpi_ec_flushed(ec);
 970         spin_unlock_irqrestore(&ec->lock, flags);
 971         return flushed;
 972 }
 973
 974 static void acpi_ec_stop(struct acpi_ec *ec, bool suspending)
 975 {
 976         unsigned long flags;
 977
 978         spin_lock_irqsave(&ec->lock, flags);
 979         if (acpi_ec_started(ec)) {
 980                 ec_dbg_drv("Stopping EC");
 981                 set_bit(EC_FLAGS_STOPPED, &ec->flags);
 982                 spin_unlock_irqrestore(&ec->lock, flags);
 983                 wait_event(ec->wait, acpi_ec_stopped(ec));
 984                 spin_lock_irqsave(&ec->lock, flags);
 985                 /* Disable GPE for event processing (SCI_EVT=1) */
 986                 if (!suspending) {
 987                         acpi_ec_complete_request(ec);
 988                         ec_dbg_ref(ec, "Decrease driver");
 989                 } else if (!ec_freeze_events)
 990                         __acpi_ec_disable_event(ec);
 991                 clear_bit(EC_FLAGS_STARTED, &ec->flags);
 992                 clear_bit(EC_FLAGS_STOPPED, &ec->flags);
 993                 ec_log_drv("EC stopped");
 994         }
 995         spin_unlock_irqrestore(&ec->lock, flags);
 996 }
 997
 998 void acpi_ec_block_transactions(void)
 999 {
1000         struct acpi_ec *ec = first_ec;
1001
1002         if (!ec)
1003                 return;
1004
1005         mutex_lock(&ec->mutex);
1006         /* Prevent transactions from being carried out */
1007         acpi_ec_stop(ec, true);
1008         mutex_unlock(&ec->mutex);
1009 }
1010
1011 void acpi_ec_unblock_transactions(void)
1012 {
1013         /*
1014          * Allow transactions to happen again (this function is called from
1015          * atomic context during wakeup, so we don't need to acquire the mutex).
1016          */
1017         if (first_ec)
1018                 acpi_ec_start(first_ec, true);
1019 }
1020
1021 /* --------------------------------------------------------------------------
1022                                 Event Management
1023    -------------------------------------------------------------------------- */
1024 static struct acpi_ec_query_handler *
1025 acpi_ec_get_query_handler(struct acpi_ec_query_handler *handler)
1026 {
1027         if (handler)
1028                 kref_get(&handler->kref);
1029         return handler;
1030 }
1031
1032 static struct acpi_ec_query_handler *
1033 acpi_ec_get_query_handler_by_value(struct acpi_ec *ec, u8 value)
1034 {
1035         struct acpi_ec_query_handler *handler;
1036         bool found = false;
1037
1038         mutex_lock(&ec->mutex);
1039         list_for_each_entry(handler, &ec->list, node) {
1040                 if (value == handler->query_bit) {
1041                         found = true;
1042                         break;
1043                 }
1044         }
1045         mutex_unlock(&ec->mutex);
1046         return found ? acpi_ec_get_query_handler(handler) : NULL;
1047 }
1048
1049 static void acpi_ec_query_handler_release(struct kref *kref)
1050 {
1051         struct acpi_ec_query_handler *handler =
1052                 container_of(kref, struct acpi_ec_query_handler, kref);
1053
1054         kfree(handler);
1055 }
1056
1057 static void acpi_ec_put_query_handler(struct acpi_ec_query_handler *handler)
1058 {
1059         kref_put(&handler->kref, acpi_ec_query_handler_release);
1060 }
1061
1062 int acpi_ec_add_query_handler(struct acpi_ec *ec, u8 query_bit,
1063                               acpi_handle handle, acpi_ec_query_func func,
1064                               void *data)
1065 {
1066         struct acpi_ec_query_handler *handler =
1067             kzalloc(sizeof(struct acpi_ec_query_handler), GFP_KERNEL);
1068
1069         if (!handler)
1070                 return -ENOMEM;
1071
1072         handler->query_bit = query_bit;
1073         handler->handle = handle;
1074         handler->func = func;
1075         handler->data = data;
1076         mutex_lock(&ec->mutex);
1077         kref_init(&handler->kref);
1078         list_add(&handler->node, &ec->list);
1079         mutex_unlock(&ec->mutex);
1080         return 0;
1081 }
1082 EXPORT_SYMBOL_GPL(acpi_ec_add_query_handler);
1083
1084 static void acpi_ec_remove_query_handlers(struct acpi_ec *ec,
1085                                           bool remove_all, u8 query_bit)
1086 {
1087         struct acpi_ec_query_handler *handler, *tmp;
1088         LIST_HEAD(free_list);
1089
1090         mutex_lock(&ec->mutex);
1091         list_for_each_entry_safe(handler, tmp, &ec->list, node) {
1092                 if (remove_all || query_bit == handler->query_bit) {
1093                         list_del_init(&handler->node);
1094                         list_add(&handler->node, &free_list);
1095                 }
1096         }
1097         mutex_unlock(&ec->mutex);
1098         list_for_each_entry_safe(handler, tmp, &free_list, node)
1099                 acpi_ec_put_query_handler(handler);
1100 }
1101
1102 void acpi_ec_remove_query_handler(struct acpi_ec *ec, u8 query_bit)
1103 {
1104         acpi_ec_remove_query_handlers(ec, false, query_bit);
1105 }
1106 EXPORT_SYMBOL_GPL(acpi_ec_remove_query_handler);
1107
1108 static struct acpi_ec_query *acpi_ec_create_query(u8 *pval)
1109 {
1110         struct acpi_ec_query *q;
1111         struct transaction *t;
1112
1113         q = kzalloc(sizeof (struct acpi_ec_query), GFP_KERNEL);
1114         if (!q)
1115                 return NULL;
1116         INIT_WORK(&q->work, acpi_ec_event_processor);
1117         t = &q->transaction;
1118         t->command = ACPI_EC_COMMAND_QUERY;
1119         t->rdata = pval;
1120         t->rlen = 1;
1121         return q;
1122 }
1123
1124 static void acpi_ec_delete_query(struct acpi_ec_query *q)
1125 {
1126         if (q) {
1127                 if (q->handler)
1128                         acpi_ec_put_query_handler(q->handler);
1129                 kfree(q);
1130         }
1131 }
1132
1133 static void acpi_ec_event_processor(struct work_struct *work)
1134 {
1135         struct acpi_ec_query *q = container_of(work, struct acpi_ec_query, work);
1136         struct acpi_ec_query_handler *handler = q->handler;
1137
1138         ec_dbg_evt("Query(0x%02x) started", handler->query_bit);
1139         if (handler->func)
1140                 handler->func(handler->data);
1141         else if (handler->handle)
1142                 acpi_evaluate_object(handler->handle, NULL, NULL, NULL);
1143         ec_dbg_evt("Query(0x%02x) stopped", handler->query_bit);
1144         acpi_ec_delete_query(q);
1145 }
1146
1147 static int acpi_ec_query(struct acpi_ec *ec, u8 *data)
1148 {
1149         u8 value = 0;
1150         int result;
1151         struct acpi_ec_query *q;
1152
1153         q = acpi_ec_create_query(&value);
1154         if (!q)
1155                 return -ENOMEM;
1156
1157         /*
1158          * Query the EC to find out which _Qxx method we need to evaluate.
1159          * Note that successful completion of the query causes the ACPI_EC_SCI
1160          * bit to be cleared (and thus clearing the interrupt source).
1161          */
1162         result = acpi_ec_transaction(ec, &q->transaction);
1163         if (!value)
1164                 result = -ENODATA;
1165         if (result)
1166                 goto err_exit;
1167
1168         q->handler = acpi_ec_get_query_handler_by_value(ec, value);
1169         if (!q->handler) {
1170                 result = -ENODATA;
1171                 goto err_exit;
1172         }
1173
1174         /*
1175          * It is reported that _Qxx are evaluated in a parallel way on
1176          * Windows:
1177          * https://bugzilla.kernel.org/show_bug.cgi?id=94411
1178          *
1179          * Put this log entry before schedule_work() in order to make
1180          * it appearing before any other log entries occurred during the
1181          * work queue execution.
1182          */
1183         ec_dbg_evt("Query(0x%02x) scheduled", value);
1184         if (!queue_work(ec_query_wq, &q->work)) {
1185                 ec_dbg_evt("Query(0x%02x) overlapped", value);
1186                 result = -EBUSY;
1187         }
1188
1189 err_exit:
1190         if (result)
1191                 acpi_ec_delete_query(q);
1192         if (data)
1193                 *data = value;
1194         return result;
1195 }
1196
1197 static void acpi_ec_check_event(struct acpi_ec *ec)
1198 {
1199         unsigned long flags;
1200
1201         if (ec_event_clearing == ACPI_EC_EVT_TIMING_EVENT) {
1202                 if (ec_guard(ec)) {
1203                         spin_lock_irqsave(&ec->lock, flags);
1204                         /*
1205                          * Take care of the SCI_EVT unless no one else is
1206                          * taking care of it.
1207                          */
1208                         if (!ec->curr)
1209                                 advance_transaction(ec);
1210                         spin_unlock_irqrestore(&ec->lock, flags);
1211                 }
1212         }
1213 }
1214
1215 static void acpi_ec_event_handler(struct work_struct *work)
1216 {
1217         unsigned long flags;
1218         struct acpi_ec *ec = container_of(work, struct acpi_ec, work);
1219
1220         ec_dbg_evt("Event started");
1221
1222         spin_lock_irqsave(&ec->lock, flags);
1223         while (ec->nr_pending_queries) {
1224                 spin_unlock_irqrestore(&ec->lock, flags);
1225                 (void)acpi_ec_query(ec, NULL);
1226                 spin_lock_irqsave(&ec->lock, flags);
1227                 ec->nr_pending_queries--;
1228                 /*
1229                  * Before exit, make sure that this work item can be
1230                  * scheduled again. There might be QR_EC failures, leaving
1231                  * EC_FLAGS_QUERY_PENDING uncleared and preventing this work
1232                  * item from being scheduled again.
1233                  */
1234                 if (!ec->nr_pending_queries) {
1235                         if (ec_event_clearing == ACPI_EC_EVT_TIMING_STATUS ||
1236                             ec_event_clearing == ACPI_EC_EVT_TIMING_QUERY)
1237                                 acpi_ec_complete_query(ec);
1238                 }
1239         }
1240         spin_unlock_irqrestore(&ec->lock, flags);
1241
1242         ec_dbg_evt("Event stopped");
1243
1244         acpi_ec_check_event(ec);
1245 }
1246
1247 static u32 acpi_ec_gpe_handler(acpi_handle gpe_device,
1248         u32 gpe_number, void *data)
1249 {
1250         unsigned long flags;
1251         struct acpi_ec *ec = data;
1252
1253         spin_lock_irqsave(&ec->lock, flags);
1254         advance_transaction(ec);
1255         spin_unlock_irqrestore(&ec->lock, flags);
1256         return ACPI_INTERRUPT_HANDLED;
1257 }
1258
1259 /* --------------------------------------------------------------------------
1260  *                           Address Space Management
1261  * -------------------------------------------------------------------------- */
1262
1263 static acpi_status
1264 acpi_ec_space_handler(u32 function, acpi_physical_address address,
1265                       u32 bits, u64 *value64,
1266                       void *handler_context, void *region_context)
1267 {
1268         struct acpi_ec *ec = handler_context;
1269         int result = 0, i, bytes = bits / 8;
1270         u8 *value = (u8 *)value64;
1271
1272         if ((address > 0xFF) || !value || !handler_context)
1273                 return AE_BAD_PARAMETER;
1274
1275         if (function != ACPI_READ && function != ACPI_WRITE)
1276                 return AE_BAD_PARAMETER;
1277
1278         if (ec_busy_polling || bits > 8)
1279                 acpi_ec_burst_enable(ec);
1280
1281         for (i = 0; i < bytes; ++i, ++address, ++value)
1282                 result = (function == ACPI_READ) ?
1283                         acpi_ec_read(ec, address, value) :
1284                         acpi_ec_write(ec, address, *value);
1285
1286         if (ec_busy_polling || bits > 8)
1287                 acpi_ec_burst_disable(ec);
1288
1289         switch (result) {
1290         case -EINVAL:
1291                 return AE_BAD_PARAMETER;
1292         case -ENODEV:
1293                 return AE_NOT_FOUND;
1294         case -ETIME:
1295                 return AE_TIME;
1296         default:
1297                 return AE_OK;
1298         }
1299 }
1300
1301 /* --------------------------------------------------------------------------
1302  *                             Driver Interface
1303  * -------------------------------------------------------------------------- */
1304
1305 static acpi_status
1306 ec_parse_io_ports(struct acpi_resource *resource, void *context);
1307
1308 static void acpi_ec_free(struct acpi_ec *ec)
1309 {
1310         if (first_ec == ec)
1311                 first_ec = NULL;
1312         if (boot_ec == ec)
1313                 boot_ec = NULL;
1314         kfree(ec);
1315 }
1316
1317 static struct acpi_ec *acpi_ec_alloc(void)
1318 {
1319         struct acpi_ec *ec = kzalloc(sizeof(struct acpi_ec), GFP_KERNEL);
1320
1321         if (!ec)
1322                 return NULL;
1323         mutex_init(&ec->mutex);
1324         init_waitqueue_head(&ec->wait);
1325         INIT_LIST_HEAD(&ec->list);
1326         spin_lock_init(&ec->lock);
1327         INIT_WORK(&ec->work, acpi_ec_event_handler);
1328         ec->timestamp = jiffies;
1329         return ec;
1330 }
1331
1332 static acpi_status
1333 acpi_ec_register_query_methods(acpi_handle handle, u32 level,
1334                                void *context, void **return_value)
1335 {
1336         char node_name[5];
1337         struct acpi_buffer buffer = { sizeof(node_name), node_name };
1338         struct acpi_ec *ec = context;
1339         int value = 0;
1340         acpi_status status;
1341
1342         status = acpi_get_name(handle, ACPI_SINGLE_NAME, &buffer);
1343
1344         if (ACPI_SUCCESS(status) && sscanf(node_name, "_Q%x", &value) == 1)
1345                 acpi_ec_add_query_handler(ec, value, handle, NULL, NULL);
1346         return AE_OK;
1347 }
1348
1349 static acpi_status
1350 ec_parse_device(acpi_handle handle, u32 Level, void *context, void **retval)
1351 {
1352         acpi_status status;
1353         unsigned long long tmp = 0;
1354         struct acpi_ec *ec = context;
1355
1356         /* clear addr values, ec_parse_io_ports depend on it */
1357         ec->command_addr = ec->data_addr = 0;
1358
1359         status = acpi_walk_resources(handle, METHOD_NAME__CRS,
1360                                      ec_parse_io_ports, ec);
1361         if (ACPI_FAILURE(status))
1362                 return status;
1363
1364         /* Get GPE bit assignment (EC events). */
1365         /* TODO: Add support for _GPE returning a package */
1366         status = acpi_evaluate_integer(handle, "_GPE", NULL, &tmp);
1367         if (ACPI_FAILURE(status))
1368                 return status;
1369         ec->gpe = tmp;
1370         /* Use the global lock for all EC transactions? */
1371         tmp = 0;
1372         acpi_evaluate_integer(handle, "_GLK", NULL, &tmp);
1373         ec->global_lock = tmp;
1374         ec->handle = handle;
1375         return AE_CTRL_TERMINATE;
1376 }
1377
1378 /*
1379  * Note: This function returns an error code only when the address space
1380  *       handler is not installed, which means "not able to handle
1381  *       transactions".
1382  */
1383 static int ec_install_handlers(struct acpi_ec *ec)
1384 {
1385         acpi_status status;
1386
1387         acpi_ec_start(ec, false);
1388
1389         if (!test_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags)) {
1390                 status = acpi_install_address_space_handler(ec->handle,
1391                                                             ACPI_ADR_SPACE_EC,
1392                                                             &acpi_ec_space_handler,
1393                                                             NULL, ec);
1394                 if (ACPI_FAILURE(status)) {
1395                         if (status == AE_NOT_FOUND) {
1396                                 /*
1397                                  * Maybe OS fails in evaluating the _REG
1398                                  * object. The AE_NOT_FOUND error will be
1399                                  * ignored and OS * continue to initialize
1400                                  * EC.
1401                                  */
1402                                 pr_err("Fail in evaluating the _REG object"
1403                                         " of EC device. Broken bios is suspected.\n");
1404                         } else {
1405                                 acpi_ec_stop(ec, false);
1406                                 return -ENODEV;
1407                         }
1408                 }
1409                 set_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags);
1410         }
1411
1412         if (!test_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags)) {
1413                 status = acpi_install_gpe_raw_handler(NULL, ec->gpe,
1414                                           ACPI_GPE_EDGE_TRIGGERED,
1415                                           &acpi_ec_gpe_handler, ec);
1416                 /* This is not fatal as we can poll EC events */
1417                 if (ACPI_SUCCESS(status)) {
1418                         set_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags);
1419                         if (test_bit(EC_FLAGS_STARTED, &ec->flags) &&
1420                             ec->reference_count >= 1)
1421                                 acpi_ec_enable_gpe(ec, true);
1422                 }
1423         }
1424
1425         return 0;
1426 }
1427
1428 static void ec_remove_handlers(struct acpi_ec *ec)
1429 {
1430         if (test_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags)) {
1431                 if (ACPI_FAILURE(acpi_remove_address_space_handler(ec->handle,
1432                                         ACPI_ADR_SPACE_EC, &acpi_ec_space_handler)))
1433                         pr_err("failed to remove space handler\n");
1434                 clear_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags);
1435         }
1436
1437         /*
1438          * Stops handling the EC transactions after removing the operation
1439          * region handler. This is required because _REG(DISCONNECT)
1440          * invoked during the removal can result in new EC transactions.
1441          *
1442          * Flushes the EC requests and thus disables the GPE before
1443          * removing the GPE handler. This is required by the current ACPICA
1444          * GPE core. ACPICA GPE core will automatically disable a GPE when
1445          * it is indicated but there is no way to handle it. So the drivers
1446          * must disable the GPEs prior to removing the GPE handlers.
1447          */
1448         acpi_ec_stop(ec, false);
1449
1450         if (test_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags)) {
1451                 if (ACPI_FAILURE(acpi_remove_gpe_handler(NULL, ec->gpe,
1452                                         &acpi_ec_gpe_handler)))
1453                         pr_err("failed to remove gpe handler\n");
1454                 clear_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags);
1455         }
1456 }
1457
1458 static int acpi_ec_setup(struct acpi_ec *ec)
1459 {
1460         int ret;
1461
1462         ret = ec_install_handlers(ec);
1463         if (ret)
1464                 return ret;
1465
1466         /* First EC capable of handling transactions */
1467         if (!first_ec) {
1468                 first_ec = ec;
1469                 acpi_handle_info(first_ec->handle, "Used as first EC\n");
1470         }
1471
1472         acpi_handle_info(ec->handle,
1473                          "GPE=0x%lx, EC_CMD/EC_SC=0x%lx, EC_DATA=0x%lx\n",
1474                          ec->gpe, ec->command_addr, ec->data_addr);
1475         return ret;
1476 }
1477
1478 static int acpi_config_boot_ec(struct acpi_ec *ec, bool is_ecdt)
1479 {
1480         int ret;
1481
1482         if (boot_ec)
1483                 ec_remove_handlers(boot_ec);
1484
1485         /* Unset old boot EC */
1486         if (boot_ec != ec)
1487                 acpi_ec_free(boot_ec);
1488
1489         ret = acpi_ec_setup(ec);
1490         if (ret)
1491                 return ret;
1492
1493         /* Set new boot EC */
1494         if (!boot_ec) {
1495                 boot_ec = ec;
1496                 boot_ec_is_ecdt = is_ecdt;
1497                 acpi_handle_info(boot_ec->handle, "Used as boot %s EC\n",
1498                                  is_ecdt ? "ECDT" : "DSDT");
1499         }
1500         return ret;
1501 }
1502
1503 static int acpi_ec_add(struct acpi_device *device)
1504 {
1505         struct acpi_ec *ec = NULL;
1506         int ret;
1507
1508         strcpy(acpi_device_name(device), ACPI_EC_DEVICE_NAME);
1509         strcpy(acpi_device_class(device), ACPI_EC_CLASS);
1510
1511         ec = acpi_ec_alloc();
1512         if (!ec)
1513                 return -ENOMEM;
1514         if (ec_parse_device(device->handle, 0, ec, NULL) !=
1515                 AE_CTRL_TERMINATE) {
1516                         acpi_ec_free(ec);
1517                         return -EINVAL;
1518         }
1519
1520         /* Find and register all query methods */
1521         acpi_walk_namespace(ACPI_TYPE_METHOD, ec->handle, 1,
1522                             acpi_ec_register_query_methods, NULL, ec, NULL);
1523
1524         device->driver_data = ec;
1525
1526         ret = !!request_region(ec->data_addr, 1, "EC data");
1527         WARN(!ret, "Could not request EC data io port 0x%lx", ec->data_addr);
1528         ret = !!request_region(ec->command_addr, 1, "EC cmd");
1529         WARN(!ret, "Could not request EC cmd io port 0x%lx", ec->command_addr);
1530
1531         ret = acpi_config_boot_ec(ec, false);
1532
1533         /* Reprobe devices depending on the EC */
1534         acpi_walk_dep_device_list(ec->handle);
1535
1536         /* EC is fully operational, allow queries */
1537         acpi_ec_enable_event(ec);
1538         return ret;
1539 }
1540
1541 static int acpi_ec_remove(struct acpi_device *device)
1542 {
1543         struct acpi_ec *ec;
1544
1545         if (!device)
1546                 return -EINVAL;
1547
1548         ec = acpi_driver_data(device);
1549         ec_remove_handlers(ec);
1550         acpi_ec_remove_query_handlers(ec, true, 0);
1551         release_region(ec->data_addr, 1);
1552         release_region(ec->command_addr, 1);
1553         device->driver_data = NULL;
1554         acpi_ec_free(ec);
1555         return 0;
1556 }
1557
1558 static acpi_status
1559 ec_parse_io_ports(struct acpi_resource *resource, void *context)
1560 {
1561         struct acpi_ec *ec = context;
1562
1563         if (resource->type != ACPI_RESOURCE_TYPE_IO)
1564                 return AE_OK;
1565
1566         /*
1567          * The first address region returned is the data port, and
1568          * the second address region returned is the status/command
1569          * port.
1570          */
1571         if (ec->data_addr == 0)
1572                 ec->data_addr = resource->data.io.minimum;
1573         else if (ec->command_addr == 0)
1574                 ec->command_addr = resource->data.io.minimum;
1575         else
1576                 return AE_CTRL_TERMINATE;
1577
1578         return AE_OK;
1579 }
1580
1581 static const struct acpi_device_id ec_device_ids[] = {
1582         {"PNP0C09", 0},
1583         {"", 0},
1584 };
1585
1586 int __init acpi_ec_dsdt_probe(void)
1587 {
1588         acpi_status status;
1589         struct acpi_ec *ec;
1590         int ret;
1591
1592         ec = acpi_ec_alloc();
1593         if (!ec)
1594                 return -ENOMEM;
1595         /*
1596          * Finding EC from DSDT if there is no ECDT EC available. When this
1597          * function is invoked, ACPI tables have been fully loaded, we can
1598          * walk namespace now.
1599          */
1600         status = acpi_get_devices(ec_device_ids[0].id,
1601                                   ec_parse_device, ec, NULL);
1602         if (ACPI_FAILURE(status) || !ec->handle) {
1603                 ret = -ENODEV;
1604                 goto error;
1605         }
1606         ret = acpi_config_boot_ec(ec, false);
1607 error:
1608         if (ret)
1609                 acpi_ec_free(ec);
1610         return ret;
1611 }
1612
1613 #if 0
1614 /*
1615  * Some EC firmware variations refuses to respond QR_EC when SCI_EVT is not
1616  * set, for which case, we complete the QR_EC without issuing it to the
1617  * firmware.
1618  * https://bugzilla.kernel.org/show_bug.cgi?id=82611
1619  * https://bugzilla.kernel.org/show_bug.cgi?id=97381
1620  */
1621 static int ec_flag_query_handshake(const struct dmi_system_id *id)
1622 {
1623         pr_debug("Detected the EC firmware requiring QR_EC issued when SCI_EVT set\n");
1624         EC_FLAGS_QUERY_HANDSHAKE = 1;
1625         return 0;
1626 }
1627 #endif
1628
1629 /*
1630  * On some hardware it is necessary to clear events accumulated by the EC during
1631  * sleep. These ECs stop reporting GPEs until they are manually polled, if too
1632  * many events are accumulated. (e.g. Samsung Series 5/9 notebooks)
1633  *
1634  * https://bugzilla.kernel.org/show_bug.cgi?id=44161
1635  *
1636  * Ideally, the EC should also be instructed NOT to accumulate events during
1637  * sleep (which Windows seems to do somehow), but the interface to control this
1638  * behaviour is not known at this time.
1639  *
1640  * Models known to be affected are Samsung 530Uxx/535Uxx/540Uxx/550Pxx/900Xxx,
1641  * however it is very likely that other Samsung models are affected.
1642  *
1643  * On systems which don't accumulate _Q events during sleep, this extra check
1644  * should be harmless.
1645  */
1646 static int ec_clear_on_resume(const struct dmi_system_id *id)
1647 {
1648         pr_debug("Detected system needing EC poll on resume.\n");
1649         EC_FLAGS_CLEAR_ON_RESUME = 1;
1650         ec_event_clearing = ACPI_EC_EVT_TIMING_STATUS;
1651         return 0;
1652 }
1653
1654 /*
1655  * Some ECDTs contain wrong register addresses.
1656  * MSI MS-171F
1657  * https://bugzilla.kernel.org/show_bug.cgi?id=12461
1658  */
1659 static int ec_correct_ecdt(const struct dmi_system_id *id)
1660 {
1661         pr_debug("Detected system needing ECDT address correction.\n");
1662         EC_FLAGS_CORRECT_ECDT = 1;
1663         return 0;
1664 }
1665
1666 static struct dmi_system_id ec_dmi_table[] __initdata = {
1667         {
1668         ec_correct_ecdt, "MSI MS-171F", {
1669         DMI_MATCH(DMI_SYS_VENDOR, "Micro-Star"),
1670         DMI_MATCH(DMI_PRODUCT_NAME, "MS-171F"),}, NULL},
1671         {
1672         ec_clear_on_resume, "Samsung hardware", {
1673         DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD.")}, NULL},
1674         {},
1675 };
1676
1677 int __init acpi_ec_ecdt_probe(void)
1678 {
1679         int ret;
1680         acpi_status status;
1681         struct acpi_table_ecdt *ecdt_ptr;
1682         struct acpi_ec *ec;
1683
1684         ec = acpi_ec_alloc();
1685         if (!ec)
1686                 return -ENOMEM;
1687         /*
1688          * Generate a boot ec context
1689          */
1690         dmi_check_system(ec_dmi_table);
1691         status = acpi_get_table(ACPI_SIG_ECDT, 1,
1692                                 (struct acpi_table_header **)&ecdt_ptr);
1693         if (ACPI_FAILURE(status)) {
1694                 ret = -ENODEV;
1695                 goto error;
1696         }
1697
1698         if (!ecdt_ptr->control.address || !ecdt_ptr->data.address) {
1699                 /*
1700                  * Asus X50GL:
1701                  * https://bugzilla.kernel.org/show_bug.cgi?id=11880
1702                  */
1703                 ret = -ENODEV;
1704                 goto error;
1705         }
1706
1707         if (EC_FLAGS_CORRECT_ECDT) {
1708                 ec->command_addr = ecdt_ptr->data.address;
1709                 ec->data_addr = ecdt_ptr->control.address;
1710         } else {
1711                 ec->command_addr = ecdt_ptr->control.address;
1712                 ec->data_addr = ecdt_ptr->data.address;
1713         }
1714         ec->gpe = ecdt_ptr->gpe;
1715         ec->handle = ACPI_ROOT_OBJECT;
1716         ret = acpi_config_boot_ec(ec, true);
1717 error:
1718         if (ret)
1719                 acpi_ec_free(ec);
1720         return ret;
1721 }
1722
1723 #ifdef CONFIG_PM_SLEEP
1724 static void acpi_ec_enter_noirq(struct acpi_ec *ec)
1725 {
1726         unsigned long flags;
1727
1728         if (ec == first_ec) {
1729                 spin_lock_irqsave(&ec->lock, flags);
1730                 ec->saved_busy_polling = ec_busy_polling;
1731                 ec->saved_polling_guard = ec_polling_guard;
1732                 ec_busy_polling = true;
1733                 ec_polling_guard = 0;
1734                 ec_log_drv("interrupt blocked");
1735                 spin_unlock_irqrestore(&ec->lock, flags);
1736         }
1737 }
1738
1739 static void acpi_ec_leave_noirq(struct acpi_ec *ec)
1740 {
1741         unsigned long flags;
1742
1743         if (ec == first_ec) {
1744                 spin_lock_irqsave(&ec->lock, flags);
1745                 ec_busy_polling = ec->saved_busy_polling;
1746                 ec_polling_guard = ec->saved_polling_guard;
1747                 ec_log_drv("interrupt unblocked");
1748                 spin_unlock_irqrestore(&ec->lock, flags);
1749         }
1750 }
1751
1752 static int acpi_ec_suspend_noirq(struct device *dev)
1753 {
1754         struct acpi_ec *ec =
1755                 acpi_driver_data(to_acpi_device(dev));
1756
1757         acpi_ec_enter_noirq(ec);
1758         return 0;
1759 }
1760
1761 static int acpi_ec_resume_noirq(struct device *dev)
1762 {
1763         struct acpi_ec *ec =
1764                 acpi_driver_data(to_acpi_device(dev));
1765
1766         acpi_ec_leave_noirq(ec);
1767         return 0;
1768 }
1769
1770 static int acpi_ec_suspend(struct device *dev)
1771 {
1772         struct acpi_ec *ec =
1773                 acpi_driver_data(to_acpi_device(dev));
1774
1775         if (ec_freeze_events)
1776                 acpi_ec_disable_event(ec);
1777         return 0;
1778 }
1779
1780 static int acpi_ec_resume(struct device *dev)
1781 {
1782         struct acpi_ec *ec =
1783                 acpi_driver_data(to_acpi_device(dev));
1784
1785         acpi_ec_enable_event(ec);
1786         return 0;
1787 }
1788 #endif
1789
1790 static const struct dev_pm_ops acpi_ec_pm = {
1791         SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(acpi_ec_suspend_noirq, acpi_ec_resume_noirq)
1792         SET_SYSTEM_SLEEP_PM_OPS(acpi_ec_suspend, acpi_ec_resume)
1793 };
1794
1795 static int param_set_event_clearing(const char *val, struct kernel_param *kp)
1796 {
1797         int result = 0;
1798
1799         if (!strncmp(val, "status", sizeof("status") - 1)) {
1800                 ec_event_clearing = ACPI_EC_EVT_TIMING_STATUS;
1801                 pr_info("Assuming SCI_EVT clearing on EC_SC accesses\n");
1802         } else if (!strncmp(val, "query", sizeof("query") - 1)) {
1803                 ec_event_clearing = ACPI_EC_EVT_TIMING_QUERY;
1804                 pr_info("Assuming SCI_EVT clearing on QR_EC writes\n");
1805         } else if (!strncmp(val, "event", sizeof("event") - 1)) {
1806                 ec_event_clearing = ACPI_EC_EVT_TIMING_EVENT;
1807                 pr_info("Assuming SCI_EVT clearing on event reads\n");
1808         } else
1809                 result = -EINVAL;
1810         return result;
1811 }
1812
1813 static int param_get_event_clearing(char *buffer, struct kernel_param *kp)
1814 {
1815         switch (ec_event_clearing) {
1816         case ACPI_EC_EVT_TIMING_STATUS:
1817                 return sprintf(buffer, "status");
1818         case ACPI_EC_EVT_TIMING_QUERY:
1819                 return sprintf(buffer, "query");
1820         case ACPI_EC_EVT_TIMING_EVENT:
1821                 return sprintf(buffer, "event");
1822         default:
1823                 return sprintf(buffer, "invalid");
1824         }
1825         return 0;
1826 }
1827
1828 module_param_call(ec_event_clearing, param_set_event_clearing, param_get_event_clearing,
1829                   NULL, 0644);
1830 MODULE_PARM_DESC(ec_event_clearing, "Assumed SCI_EVT clearing timing");
1831
1832 static struct acpi_driver acpi_ec_driver = {
1833         .name = "ec",
1834         .class = ACPI_EC_CLASS,
1835         .ids = ec_device_ids,
1836         .ops = {
1837                 .add = acpi_ec_add,
1838                 .remove = acpi_ec_remove,
1839                 },
1840         .drv.pm = &acpi_ec_pm,
1841 };
1842
1843 static inline int acpi_ec_query_init(void)
1844 {
1845         if (!ec_query_wq) {
1846                 ec_query_wq = alloc_workqueue("kec_query", 0,
1847                                               ec_max_queries);
1848                 if (!ec_query_wq)
1849                         return -ENODEV;
1850         }
1851         return 0;
1852 }
1853
1854 static inline void acpi_ec_query_exit(void)
1855 {
1856         if (ec_query_wq) {
1857                 destroy_workqueue(ec_query_wq);
1858                 ec_query_wq = NULL;
1859         }
1860 }
1861
1862 int __init acpi_ec_init(void)
1863 {
1864         int result;
1865
1866         /* register workqueue for _Qxx evaluations */
1867         result = acpi_ec_query_init();
1868         if (result)
1869                 goto err_exit;
1870         /* Now register the driver for the EC */
1871         result = acpi_bus_register_driver(&acpi_ec_driver);
1872         if (result)
1873                 goto err_exit;
1874
1875 err_exit:
1876         if (result)
1877                 acpi_ec_query_exit();
1878         return result;
1879 }
1880
1881 /* EC driver currently not unloadable */
1882 #if 0
1883 static void __exit acpi_ec_exit(void)
1884 {
1885
1886         acpi_bus_unregister_driver(&acpi_ec_driver);
1887         acpi_ec_query_exit();
1888 }
1889 #endif  /* 0 */