Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2177 insertions, 0 deletions

diff --git a/drivers/acpi/ec.c b/drivers/acpi/ec.c
new file mode 100644
index 000000000..e3df3dda0
--- /dev/null
+++ b/drivers/acpi/ec.c
@@ -0,0 +1,2177 @@
+/*
+ *  ec.c - ACPI Embedded Controller Driver (v3)
+ *
+ *  Copyright (C) 2001-2015 Intel Corporation
+ *    Author: 2014, 2015 Lv Zheng <lv.zheng@intel.com>
+ *            2006, 2007 Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
+ *            2006       Denis Sadykov <denis.m.sadykov@intel.com>
+ *            2004       Luming Yu <luming.yu@intel.com>
+ *            2001, 2002 Andy Grover <andrew.grover@intel.com>
+ *            2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
+ *  Copyright (C) 2008      Alexey Starikovskiy <astarikovskiy@suse.de>
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or (at
+ *  your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful, but
+ *  WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  General Public License for more details.
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+
+/* Uncomment next line to get verbose printout */
+/* #define DEBUG */
+#define pr_fmt(fmt) "ACPI: EC: " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/acpi.h>
+#include <linux/dmi.h>
+#include <asm/io.h>
+
+#include "internal.h"
+
+#define ACPI_EC_CLASS			"embedded_controller"
+#define ACPI_EC_DEVICE_NAME		"Embedded Controller"
+#define ACPI_EC_FILE_INFO		"info"
+
+/* EC status register */
+#define ACPI_EC_FLAG_OBF	0x01	/* Output buffer full */
+#define ACPI_EC_FLAG_IBF	0x02	/* Input buffer full */
+#define ACPI_EC_FLAG_CMD	0x08	/* Input buffer contains a command */
+#define ACPI_EC_FLAG_BURST	0x10	/* burst mode */
+#define ACPI_EC_FLAG_SCI	0x20	/* EC-SCI occurred */
+
+/*
+ * The SCI_EVT clearing timing is not defined by the ACPI specification.
+ * This leads to lots of practical timing issues for the host EC driver.
+ * The following variations are defined (from the target EC firmware's
+ * perspective):
+ * STATUS: After indicating SCI_EVT edge triggered IRQ to the host, the
+ *         target can clear SCI_EVT at any time so long as the host can see
+ *         the indication by reading the status register (EC_SC). So the
+ *         host should re-check SCI_EVT after the first time the SCI_EVT
+ *         indication is seen, which is the same time the query request
+ *         (QR_EC) is written to the command register (EC_CMD). SCI_EVT set
+ *         at any later time could indicate another event. Normally such
+ *         kind of EC firmware has implemented an event queue and will
+ *         return 0x00 to indicate "no outstanding event".
+ * QUERY: After seeing the query request (QR_EC) written to the command
+ *        register (EC_CMD) by the host and having prepared the responding
+ *        event value in the data register (EC_DATA), the target can safely
+ *        clear SCI_EVT because the target can confirm that the current
+ *        event is being handled by the host. The host then should check
+ *        SCI_EVT right after reading the event response from the data
+ *        register (EC_DATA).
+ * EVENT: After seeing the event response read from the data register
+ *        (EC_DATA) by the host, the target can clear SCI_EVT. As the
+ *        target requires time to notice the change in the data register
+ *        (EC_DATA), the host may be required to wait additional guarding
+ *        time before checking the SCI_EVT again. Such guarding may not be
+ *        necessary if the host is notified via another IRQ.
+ */
+#define ACPI_EC_EVT_TIMING_STATUS	0x00
+#define ACPI_EC_EVT_TIMING_QUERY	0x01
+#define ACPI_EC_EVT_TIMING_EVENT	0x02
+
+/* EC commands */
+enum ec_command {
+	ACPI_EC_COMMAND_READ = 0x80,
+	ACPI_EC_COMMAND_WRITE = 0x81,
+	ACPI_EC_BURST_ENABLE = 0x82,
+	ACPI_EC_BURST_DISABLE = 0x83,
+	ACPI_EC_COMMAND_QUERY = 0x84,
+};
+
+#define ACPI_EC_DELAY		500	/* Wait 500ms max. during EC ops */
+#define ACPI_EC_UDELAY_GLK	1000	/* Wait 1ms max. to get global lock */
+#define ACPI_EC_UDELAY_POLL	550	/* Wait 1ms for EC transaction polling */
+#define ACPI_EC_CLEAR_MAX	100	/* Maximum number of events to query
+					 * when trying to clear the EC */
+#define ACPI_EC_MAX_QUERIES	16	/* Maximum number of parallel queries */
+
+enum {
+	EC_FLAGS_QUERY_ENABLED,		/* Query is enabled */
+	EC_FLAGS_QUERY_PENDING,		/* Query is pending */
+	EC_FLAGS_QUERY_GUARDING,	/* Guard for SCI_EVT check */
+	EC_FLAGS_GPE_HANDLER_INSTALLED,	/* GPE handler installed */
+	EC_FLAGS_EC_HANDLER_INSTALLED,	/* OpReg handler installed */
+	EC_FLAGS_EVT_HANDLER_INSTALLED, /* _Qxx handlers installed */
+	EC_FLAGS_STARTED,		/* Driver is started */
+	EC_FLAGS_STOPPED,		/* Driver is stopped */
+	EC_FLAGS_GPE_MASKED,		/* GPE masked */
+};
+
+#define ACPI_EC_COMMAND_POLL		0x01 /* Available for command byte */
+#define ACPI_EC_COMMAND_COMPLETE	0x02 /* Completed last byte */
+
+/* ec.c is compiled in acpi namespace so this shows up as acpi.ec_delay param */
+static unsigned int ec_delay __read_mostly = ACPI_EC_DELAY;
+module_param(ec_delay, uint, 0644);
+MODULE_PARM_DESC(ec_delay, "Timeout(ms) waited until an EC command completes");
+
+static unsigned int ec_max_queries __read_mostly = ACPI_EC_MAX_QUERIES;
+module_param(ec_max_queries, uint, 0644);
+MODULE_PARM_DESC(ec_max_queries, "Maximum parallel _Qxx evaluations");
+
+static bool ec_busy_polling __read_mostly;
+module_param(ec_busy_polling, bool, 0644);
+MODULE_PARM_DESC(ec_busy_polling, "Use busy polling to advance EC transaction");
+
+static unsigned int ec_polling_guard __read_mostly = ACPI_EC_UDELAY_POLL;
+module_param(ec_polling_guard, uint, 0644);
+MODULE_PARM_DESC(ec_polling_guard, "Guard time(us) between EC accesses in polling modes");
+
+static unsigned int ec_event_clearing __read_mostly = ACPI_EC_EVT_TIMING_QUERY;
+
+/*
+ * If the number of false interrupts per one transaction exceeds
+ * this threshold, will think there is a GPE storm happened and
+ * will disable the GPE for normal transaction.
+ */
+static unsigned int ec_storm_threshold  __read_mostly = 8;
+module_param(ec_storm_threshold, uint, 0644);
+MODULE_PARM_DESC(ec_storm_threshold, "Maxim false GPE numbers not considered as GPE storm");
+
+static bool ec_freeze_events __read_mostly = false;
+module_param(ec_freeze_events, bool, 0644);
+MODULE_PARM_DESC(ec_freeze_events, "Disabling event handling during suspend/resume");
+
+static bool ec_no_wakeup __read_mostly;
+module_param(ec_no_wakeup, bool, 0644);
+MODULE_PARM_DESC(ec_no_wakeup, "Do not wake up from suspend-to-idle");
+
+struct acpi_ec_query_handler {
+	struct list_head node;
+	acpi_ec_query_func func;
+	acpi_handle handle;
+	void *data;
+	u8 query_bit;
+	struct kref kref;
+};
+
+struct transaction {
+	const u8 *wdata;
+	u8 *rdata;
+	unsigned short irq_count;
+	u8 command;
+	u8 wi;
+	u8 ri;
+	u8 wlen;
+	u8 rlen;
+	u8 flags;
+};
+
+struct acpi_ec_query {
+	struct transaction transaction;
+	struct work_struct work;
+	struct acpi_ec_query_handler *handler;
+};
+
+static int acpi_ec_query(struct acpi_ec *ec, u8 *data);
+static void advance_transaction(struct acpi_ec *ec);
+static void acpi_ec_event_handler(struct work_struct *work);
+static void acpi_ec_event_processor(struct work_struct *work);
+
+struct acpi_ec *boot_ec, *first_ec;
+EXPORT_SYMBOL(first_ec);
+static bool boot_ec_is_ecdt = false;
+static struct workqueue_struct *ec_query_wq;
+
+static int EC_FLAGS_QUERY_HANDSHAKE; /* Needs QR_EC issued when SCI_EVT set */
+static int EC_FLAGS_CORRECT_ECDT; /* Needs ECDT port address correction */
+static int EC_FLAGS_IGNORE_DSDT_GPE; /* Needs ECDT GPE as correction setting */
+static int EC_FLAGS_CLEAR_ON_RESUME; /* Needs acpi_ec_clear() on boot/resume */
+
+/* --------------------------------------------------------------------------
+ *                           Logging/Debugging
+ * -------------------------------------------------------------------------- */
+
+/*
+ * Splitters used by the developers to track the boundary of the EC
+ * handling processes.
+ */
+#ifdef DEBUG
+#define EC_DBG_SEP	" "
+#define EC_DBG_DRV	"+++++"
+#define EC_DBG_STM	"====="
+#define EC_DBG_REQ	"*****"
+#define EC_DBG_EVT	"#####"
+#else
+#define EC_DBG_SEP	""
+#define EC_DBG_DRV
+#define EC_DBG_STM
+#define EC_DBG_REQ
+#define EC_DBG_EVT
+#endif
+
+#define ec_log_raw(fmt, ...) \
+	pr_info(fmt "\n", ##__VA_ARGS__)
+#define ec_dbg_raw(fmt, ...) \
+	pr_debug(fmt "\n", ##__VA_ARGS__)
+#define ec_log(filter, fmt, ...) \
+	ec_log_raw(filter EC_DBG_SEP fmt EC_DBG_SEP filter, ##__VA_ARGS__)
+#define ec_dbg(filter, fmt, ...) \
+	ec_dbg_raw(filter EC_DBG_SEP fmt EC_DBG_SEP filter, ##__VA_ARGS__)
+
+#define ec_log_drv(fmt, ...) \
+	ec_log(EC_DBG_DRV, fmt, ##__VA_ARGS__)
+#define ec_dbg_drv(fmt, ...) \
+	ec_dbg(EC_DBG_DRV, fmt, ##__VA_ARGS__)
+#define ec_dbg_stm(fmt, ...) \
+	ec_dbg(EC_DBG_STM, fmt, ##__VA_ARGS__)
+#define ec_dbg_req(fmt, ...) \
+	ec_dbg(EC_DBG_REQ, fmt, ##__VA_ARGS__)
+#define ec_dbg_evt(fmt, ...) \
+	ec_dbg(EC_DBG_EVT, fmt, ##__VA_ARGS__)
+#define ec_dbg_ref(ec, fmt, ...) \
+	ec_dbg_raw("%lu: " fmt, ec->reference_count, ## __VA_ARGS__)
+
+/* --------------------------------------------------------------------------
+ *                           Device Flags
+ * -------------------------------------------------------------------------- */
+
+static bool acpi_ec_started(struct acpi_ec *ec)
+{
+	return test_bit(EC_FLAGS_STARTED, &ec->flags) &&
+	       !test_bit(EC_FLAGS_STOPPED, &ec->flags);
+}
+
+static bool acpi_ec_event_enabled(struct acpi_ec *ec)
+{
+	/*
+	 * There is an OSPM early stage logic. During the early stages
+	 * (boot/resume), OSPMs shouldn't enable the event handling, only
+	 * the EC transactions are allowed to be performed.
+	 */
+	if (!test_bit(EC_FLAGS_QUERY_ENABLED, &ec->flags))
+		return false;
+	/*
+	 * However, disabling the event handling is experimental for late
+	 * stage (suspend), and is controlled by the boot parameter of
+	 * "ec_freeze_events":
+	 * 1. true:  The EC event handling is disabled before entering
+	 *           the noirq stage.
+	 * 2. false: The EC event handling is automatically disabled as
+	 *           soon as the EC driver is stopped.
+	 */
+	if (ec_freeze_events)
+		return acpi_ec_started(ec);
+	else
+		return test_bit(EC_FLAGS_STARTED, &ec->flags);
+}
+
+static bool acpi_ec_flushed(struct acpi_ec *ec)
+{
+	return ec->reference_count == 1;
+}
+
+/* --------------------------------------------------------------------------
+ *                           EC Registers
+ * -------------------------------------------------------------------------- */
+
+static inline u8 acpi_ec_read_status(struct acpi_ec *ec)
+{
+	u8 x = inb(ec->command_addr);
+
+	ec_dbg_raw("EC_SC(R) = 0x%2.2x "
+		   "SCI_EVT=%d BURST=%d CMD=%d IBF=%d OBF=%d",
+		   x,
+		   !!(x & ACPI_EC_FLAG_SCI),
+		   !!(x & ACPI_EC_FLAG_BURST),
+		   !!(x & ACPI_EC_FLAG_CMD),
+		   !!(x & ACPI_EC_FLAG_IBF),
+		   !!(x & ACPI_EC_FLAG_OBF));
+	return x;
+}
+
+static inline u8 acpi_ec_read_data(struct acpi_ec *ec)
+{
+	u8 x = inb(ec->data_addr);
+
+	ec->timestamp = jiffies;
+	ec_dbg_raw("EC_DATA(R) = 0x%2.2x", x);
+	return x;
+}
+
+static inline void acpi_ec_write_cmd(struct acpi_ec *ec, u8 command)
+{
+	ec_dbg_raw("EC_SC(W) = 0x%2.2x", command);
+	outb(command, ec->command_addr);
+	ec->timestamp = jiffies;
+}
+
+static inline void acpi_ec_write_data(struct acpi_ec *ec, u8 data)
+{
+	ec_dbg_raw("EC_DATA(W) = 0x%2.2x", data);
+	outb(data, ec->data_addr);
+	ec->timestamp = jiffies;
+}
+
+#if defined(DEBUG) || defined(CONFIG_DYNAMIC_DEBUG)
+static const char *acpi_ec_cmd_string(u8 cmd)
+{
+	switch (cmd) {
+	case 0x80:
+		return "RD_EC";
+	case 0x81:
+		return "WR_EC";
+	case 0x82:
+		return "BE_EC";
+	case 0x83:
+		return "BD_EC";
+	case 0x84:
+		return "QR_EC";
+	}
+	return "UNKNOWN";
+}
+#else
+#define acpi_ec_cmd_string(cmd)		"UNDEF"
+#endif
+
+/* --------------------------------------------------------------------------
+ *                           GPE Registers
+ * -------------------------------------------------------------------------- */
+
+static inline bool acpi_ec_is_gpe_raised(struct acpi_ec *ec)
+{
+	acpi_event_status gpe_status = 0;
+
+	(void)acpi_get_gpe_status(NULL, ec->gpe, &gpe_status);
+	return (gpe_status & ACPI_EVENT_FLAG_STATUS_SET) ? true : false;
+}
+
+static inline void acpi_ec_enable_gpe(struct acpi_ec *ec, bool open)
+{
+	if (open)
+		acpi_enable_gpe(NULL, ec->gpe);
+	else {
+		BUG_ON(ec->reference_count < 1);
+		acpi_set_gpe(NULL, ec->gpe, ACPI_GPE_ENABLE);
+	}
+	if (acpi_ec_is_gpe_raised(ec)) {
+		/*
+		 * On some platforms, EN=1 writes cannot trigger GPE. So
+		 * software need to manually trigger a pseudo GPE event on
+		 * EN=1 writes.
+		 */
+		ec_dbg_raw("Polling quirk");
+		advance_transaction(ec);
+	}
+}
+
+static inline void acpi_ec_disable_gpe(struct acpi_ec *ec, bool close)
+{
+	if (close)
+		acpi_disable_gpe(NULL, ec->gpe);
+	else {
+		BUG_ON(ec->reference_count < 1);
+		acpi_set_gpe(NULL, ec->gpe, ACPI_GPE_DISABLE);
+	}
+}
+
+static inline void acpi_ec_clear_gpe(struct acpi_ec *ec)
+{
+	/*
+	 * GPE STS is a W1C register, which means:
+	 * 1. Software can clear it without worrying about clearing other
+	 *    GPEs' STS bits when the hardware sets them in parallel.
+	 * 2. As long as software can ensure only clearing it when it is
+	 *    set, hardware won't set it in parallel.
+	 * So software can clear GPE in any contexts.
+	 * Warning: do not move the check into advance_transaction() as the
+	 * EC commands will be sent without GPE raised.
+	 */
+	if (!acpi_ec_is_gpe_raised(ec))
+		return;
+	acpi_clear_gpe(NULL, ec->gpe);
+}
+
+/* --------------------------------------------------------------------------
+ *                           Transaction Management
+ * -------------------------------------------------------------------------- */
+
+static void acpi_ec_submit_request(struct acpi_ec *ec)
+{
+	ec->reference_count++;
+	if (test_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags) &&
+	    ec->reference_count == 1)
+		acpi_ec_enable_gpe(ec, true);
+}
+
+static void acpi_ec_complete_request(struct acpi_ec *ec)
+{
+	bool flushed = false;
+
+	ec->reference_count--;
+	if (test_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags) &&
+	    ec->reference_count == 0)
+		acpi_ec_disable_gpe(ec, true);
+	flushed = acpi_ec_flushed(ec);
+	if (flushed)
+		wake_up(&ec->wait);
+}
+
+static void acpi_ec_mask_gpe(struct acpi_ec *ec)
+{
+	if (!test_bit(EC_FLAGS_GPE_MASKED, &ec->flags)) {
+		acpi_ec_disable_gpe(ec, false);
+		ec_dbg_drv("Polling enabled");
+		set_bit(EC_FLAGS_GPE_MASKED, &ec->flags);
+	}
+}
+
+static void acpi_ec_unmask_gpe(struct acpi_ec *ec)
+{
+	if (test_bit(EC_FLAGS_GPE_MASKED, &ec->flags)) {
+		clear_bit(EC_FLAGS_GPE_MASKED, &ec->flags);
+		acpi_ec_enable_gpe(ec, false);
+		ec_dbg_drv("Polling disabled");
+	}
+}
+
+/*
+ * acpi_ec_submit_flushable_request() - Increase the reference count unless
+ *                                      the flush operation is not in
+ *                                      progress
+ * @ec: the EC device
+ *
+ * This function must be used before taking a new action that should hold
+ * the reference count.  If this function returns false, then the action
+ * must be discarded or it will prevent the flush operation from being
+ * completed.
+ */
+static bool acpi_ec_submit_flushable_request(struct acpi_ec *ec)
+{
+	if (!acpi_ec_started(ec))
+		return false;
+	acpi_ec_submit_request(ec);
+	return true;
+}
+
+static void acpi_ec_submit_query(struct acpi_ec *ec)
+{
+	acpi_ec_mask_gpe(ec);
+	if (!acpi_ec_event_enabled(ec))
+		return;
+	if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags)) {
+		ec_dbg_evt("Command(%s) submitted/blocked",
+			   acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
+		ec->nr_pending_queries++;
+		schedule_work(&ec->work);
+	}
+}
+
+static void acpi_ec_complete_query(struct acpi_ec *ec)
+{
+	if (test_and_clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags))
+		ec_dbg_evt("Command(%s) unblocked",
+			   acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
+	acpi_ec_unmask_gpe(ec);
+}
+
+static inline void __acpi_ec_enable_event(struct acpi_ec *ec)
+{
+	if (!test_and_set_bit(EC_FLAGS_QUERY_ENABLED, &ec->flags))
+		ec_log_drv("event unblocked");
+	/*
+	 * Unconditionally invoke this once after enabling the event
+	 * handling mechanism to detect the pending events.
+	 */
+	advance_transaction(ec);
+}
+
+static inline void __acpi_ec_disable_event(struct acpi_ec *ec)
+{
+	if (test_and_clear_bit(EC_FLAGS_QUERY_ENABLED, &ec->flags))
+		ec_log_drv("event blocked");
+}
+
+/*
+ * Process _Q events that might have accumulated in the EC.
+ * Run with locked ec mutex.
+ */
+static void acpi_ec_clear(struct acpi_ec *ec)
+{
+	int i, status;
+	u8 value = 0;
+
+	for (i = 0; i < ACPI_EC_CLEAR_MAX; i++) {
+		status = acpi_ec_query(ec, &value);
+		if (status || !value)
+			break;
+	}
+	if (unlikely(i == ACPI_EC_CLEAR_MAX))
+		pr_warn("Warning: Maximum of %d stale EC events cleared\n", i);
+	else
+		pr_info("%d stale EC events cleared\n", i);
+}
+
+static void acpi_ec_enable_event(struct acpi_ec *ec)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ec->lock, flags);
+	if (acpi_ec_started(ec))
+		__acpi_ec_enable_event(ec);
+	spin_unlock_irqrestore(&ec->lock, flags);
+
+	/* Drain additional events if hardware requires that */
+	if (EC_FLAGS_CLEAR_ON_RESUME)
+		acpi_ec_clear(ec);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static bool acpi_ec_query_flushed(struct acpi_ec *ec)
+{
+	bool flushed;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ec->lock, flags);
+	flushed = !ec->nr_pending_queries;
+	spin_unlock_irqrestore(&ec->lock, flags);
+	return flushed;
+}
+
+static void __acpi_ec_flush_event(struct acpi_ec *ec)
+{
+	/*
+	 * When ec_freeze_events is true, we need to flush events in
+	 * the proper position before entering the noirq stage.
+	 */
+	wait_event(ec->wait, acpi_ec_query_flushed(ec));
+	if (ec_query_wq)
+		flush_workqueue(ec_query_wq);
+}
+
+static void acpi_ec_disable_event(struct acpi_ec *ec)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ec->lock, flags);
+	__acpi_ec_disable_event(ec);
+	spin_unlock_irqrestore(&ec->lock, flags);
+	__acpi_ec_flush_event(ec);
+}
+
+void acpi_ec_flush_work(void)
+{
+	if (first_ec)
+		__acpi_ec_flush_event(first_ec);
+
+	flush_scheduled_work();
+}
+#endif /* CONFIG_PM_SLEEP */
+
+static bool acpi_ec_guard_event(struct acpi_ec *ec)
+{
+	bool guarded = true;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ec->lock, flags);
+	/*
+	 * If firmware SCI_EVT clearing timing is "event", we actually
+	 * don't know when the SCI_EVT will be cleared by firmware after
+	 * evaluating _Qxx, so we need to re-check SCI_EVT after waiting an
+	 * acceptable period.
+	 *
+	 * The guarding period begins when EC_FLAGS_QUERY_PENDING is
+	 * flagged, which means SCI_EVT check has just been performed.
+	 * But if the current transaction is ACPI_EC_COMMAND_QUERY, the
+	 * guarding should have already been performed (via
+	 * EC_FLAGS_QUERY_GUARDING) and should not be applied so that the
+	 * ACPI_EC_COMMAND_QUERY transaction can be transitioned into
+	 * ACPI_EC_COMMAND_POLL state immediately.
+	 */
+	if (ec_event_clearing == ACPI_EC_EVT_TIMING_STATUS ||
+	    ec_event_clearing == ACPI_EC_EVT_TIMING_QUERY ||
+	    !test_bit(EC_FLAGS_QUERY_PENDING, &ec->flags) ||
+	    (ec->curr && ec->curr->command == ACPI_EC_COMMAND_QUERY))
+		guarded = false;
+	spin_unlock_irqrestore(&ec->lock, flags);
+	return guarded;
+}
+
+static int ec_transaction_polled(struct acpi_ec *ec)
+{
+	unsigned long flags;
+	int ret = 0;
+
+	spin_lock_irqsave(&ec->lock, flags);
+	if (ec->curr && (ec->curr->flags & ACPI_EC_COMMAND_POLL))
+		ret = 1;
+	spin_unlock_irqrestore(&ec->lock, flags);
+	return ret;
+}
+
+static int ec_transaction_completed(struct acpi_ec *ec)
+{
+	unsigned long flags;
+	int ret = 0;
+
+	spin_lock_irqsave(&ec->lock, flags);
+	if (ec->curr && (ec->curr->flags & ACPI_EC_COMMAND_COMPLETE))
+		ret = 1;
+	spin_unlock_irqrestore(&ec->lock, flags);
+	return ret;
+}
+
+static inline void ec_transaction_transition(struct acpi_ec *ec, unsigned long flag)
+{
+	ec->curr->flags |= flag;
+	if (ec->curr->command == ACPI_EC_COMMAND_QUERY) {
+		if (ec_event_clearing == ACPI_EC_EVT_TIMING_STATUS &&
+		    flag == ACPI_EC_COMMAND_POLL)
+			acpi_ec_complete_query(ec);
+		if (ec_event_clearing == ACPI_EC_EVT_TIMING_QUERY &&
+		    flag == ACPI_EC_COMMAND_COMPLETE)
+			acpi_ec_complete_query(ec);
+		if (ec_event_clearing == ACPI_EC_EVT_TIMING_EVENT &&
+		    flag == ACPI_EC_COMMAND_COMPLETE)
+			set_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags);
+	}
+}
+
+static void advance_transaction(struct acpi_ec *ec)
+{
+	struct transaction *t;
+	u8 status;
+	bool wakeup = false;
+
+	ec_dbg_stm("%s (%d)", in_interrupt() ? "IRQ" : "TASK",
+		   smp_processor_id());
+	/*
+	 * By always clearing STS before handling all indications, we can
+	 * ensure a hardware STS 0->1 change after this clearing can always
+	 * trigger a GPE interrupt.
+	 */
+	acpi_ec_clear_gpe(ec);
+	status = acpi_ec_read_status(ec);
+	t = ec->curr;
+	/*
+	 * Another IRQ or a guarded polling mode advancement is detected,
+	 * the next QR_EC submission is then allowed.
+	 */
+	if (!t || !(t->flags & ACPI_EC_COMMAND_POLL)) {
+		if (ec_event_clearing == ACPI_EC_EVT_TIMING_EVENT &&
+		    (!ec->nr_pending_queries ||
+		     test_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags))) {
+			clear_bit(EC_FLAGS_QUERY_GUARDING, &ec->flags);
+			acpi_ec_complete_query(ec);
+		}
+	}
+	if (!t)
+		goto err;
+	if (t->flags & ACPI_EC_COMMAND_POLL) {
+		if (t->wlen > t->wi) {
+			if ((status & ACPI_EC_FLAG_IBF) == 0)
+				acpi_ec_write_data(ec, t->wdata[t->wi++]);
+			else
+				goto err;
+		} else if (t->rlen > t->ri) {
+			if ((status & ACPI_EC_FLAG_OBF) == 1) {
+				t->rdata[t->ri++] = acpi_ec_read_data(ec);
+				if (t->rlen == t->ri) {
+					ec_transaction_transition(ec, ACPI_EC_COMMAND_COMPLETE);
+					if (t->command == ACPI_EC_COMMAND_QUERY)
+						ec_dbg_evt("Command(%s) completed by hardware",
+							   acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
+					wakeup = true;
+				}
+			} else
+				goto err;
+		} else if (t->wlen == t->wi &&
+			   (status & ACPI_EC_FLAG_IBF) == 0) {
+			ec_transaction_transition(ec, ACPI_EC_COMMAND_COMPLETE);
+			wakeup = true;
+		}
+		goto out;
+	} else {
+		if (EC_FLAGS_QUERY_HANDSHAKE &&
+		    !(status & ACPI_EC_FLAG_SCI) &&
+		    (t->command == ACPI_EC_COMMAND_QUERY)) {
+			ec_transaction_transition(ec, ACPI_EC_COMMAND_POLL);
+			t->rdata[t->ri++] = 0x00;
+			ec_transaction_transition(ec, ACPI_EC_COMMAND_COMPLETE);
+			ec_dbg_evt("Command(%s) completed by software",
+				   acpi_ec_cmd_string(ACPI_EC_COMMAND_QUERY));
+			wakeup = true;
+		} else if ((status & ACPI_EC_FLAG_IBF) == 0) {
+			acpi_ec_write_cmd(ec, t->command);
+			ec_transaction_transition(ec, ACPI_EC_COMMAND_POLL);
+		} else
+			goto err;
+		goto out;
+	}
+err:
+	/*
+	 * If SCI bit is set, then don't think it's a false IRQ
+	 * otherwise will take a not handled IRQ as a false one.
+	 */
+	if (!(status & ACPI_EC_FLAG_SCI)) {
+		if (in_interrupt() && t) {
+			if (t->irq_count < ec_storm_threshold)
+				++t->irq_count;
+			/* Allow triggering on 0 threshold */
+			if (t->irq_count == ec_storm_threshold)
+				acpi_ec_mask_gpe(ec);
+		}
+	}
+out:
+	if (status & ACPI_EC_FLAG_SCI)
+		acpi_ec_submit_query(ec);
+	if (wakeup && in_interrupt())
+		wake_up(&ec->wait);
+}
+
+static void start_transaction(struct acpi_ec *ec)
+{
+	ec->curr->irq_count = ec->curr->wi = ec->curr->ri = 0;
+	ec->curr->flags = 0;
+}
+
+static int ec_guard(struct acpi_ec *ec)
+{
+	unsigned long guard = usecs_to_jiffies(ec->polling_guard);
+	unsigned long timeout = ec->timestamp + guard;
+
+	/* Ensure guarding period before polling EC status */
+	do {
+		if (ec->busy_polling) {
+			/* Perform busy polling */
+			if (ec_transaction_completed(ec))
+				return 0;
+			udelay(jiffies_to_usecs(guard));
+		} else {
+			/*
+			 * Perform wait polling
+			 * 1. Wait the transaction to be completed by the
+			 *    GPE handler after the transaction enters
+			 *    ACPI_EC_COMMAND_POLL state.
+			 * 2. A special guarding logic is also required
+			 *    for event clearing mode "event" before the
+			 *    transaction enters ACPI_EC_COMMAND_POLL
+			 *    state.
+			 */
+			if (!ec_transaction_polled(ec) &&
+			    !acpi_ec_guard_event(ec))
+				break;
+			if (wait_event_timeout(ec->wait,
+					       ec_transaction_completed(ec),
+					       guard))
+				return 0;
+		}
+	} while (time_before(jiffies, timeout));
+	return -ETIME;
+}
+
+static int ec_poll(struct acpi_ec *ec)
+{
+	unsigned long flags;
+	int repeat = 5; /* number of command restarts */
+
+	while (repeat--) {
+		unsigned long delay = jiffies +
+			msecs_to_jiffies(ec_delay);
+		do {
+			if (!ec_guard(ec))
+				return 0;
+			spin_lock_irqsave(&ec->lock, flags);
+			advance_transaction(ec);
+			spin_unlock_irqrestore(&ec->lock, flags);
+		} while (time_before(jiffies, delay));
+		pr_debug("controller reset, restart transaction\n");
+		spin_lock_irqsave(&ec->lock, flags);
+		start_transaction(ec);
+		spin_unlock_irqrestore(&ec->lock, flags);
+	}
+	return -ETIME;
+}
+
+static int acpi_ec_transaction_unlocked(struct acpi_ec *ec,
+					struct transaction *t)
+{
+	unsigned long tmp;
+	int ret = 0;
+
+	/* start transaction */
+	spin_lock_irqsave(&ec->lock, tmp);
+	/* Enable GPE for command processing (IBF=0/OBF=1) */
+	if (!acpi_ec_submit_flushable_request(ec)) {
+		ret = -EINVAL;
+		goto unlock;
+	}
+	ec_dbg_ref(ec, "Increase command");
+	/* following two actions should be kept atomic */
+	ec->curr = t;
+	ec_dbg_req("Command(%s) started", acpi_ec_cmd_string(t->command));
+	start_transaction(ec);
+	spin_unlock_irqrestore(&ec->lock, tmp);
+
+	ret = ec_poll(ec);
+
+	spin_lock_irqsave(&ec->lock, tmp);
+	if (t->irq_count == ec_storm_threshold)
+		acpi_ec_unmask_gpe(ec);
+	ec_dbg_req("Command(%s) stopped", acpi_ec_cmd_string(t->command));
+	ec->curr = NULL;
+	/* Disable GPE for command processing (IBF=0/OBF=1) */
+	acpi_ec_complete_request(ec);
+	ec_dbg_ref(ec, "Decrease command");
+unlock:
+	spin_unlock_irqrestore(&ec->lock, tmp);
+	return ret;
+}
+
+static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t)
+{
+	int status;
+	u32 glk;
+
+	if (!ec || (!t) || (t->wlen && !t->wdata) || (t->rlen && !t->rdata))
+		return -EINVAL;
+	if (t->rdata)
+		memset(t->rdata, 0, t->rlen);
+
+	mutex_lock(&ec->mutex);
+	if (ec->global_lock) {
+		status = acpi_acquire_global_lock(ACPI_EC_UDELAY_GLK, &glk);
+		if (ACPI_FAILURE(status)) {
+			status = -ENODEV;
+			goto unlock;
+		}
+	}
+
+	status = acpi_ec_transaction_unlocked(ec, t);
+
+	if (ec->global_lock)
+		acpi_release_global_lock(glk);
+unlock:
+	mutex_unlock(&ec->mutex);
+	return status;
+}
+
+static int acpi_ec_burst_enable(struct acpi_ec *ec)
+{
+	u8 d;
+	struct transaction t = {.command = ACPI_EC_BURST_ENABLE,
+				.wdata = NULL, .rdata = &d,
+				.wlen = 0, .rlen = 1};
+
+	return acpi_ec_transaction(ec, &t);
+}
+
+static int acpi_ec_burst_disable(struct acpi_ec *ec)
+{
+	struct transaction t = {.command = ACPI_EC_BURST_DISABLE,
+				.wdata = NULL, .rdata = NULL,
+				.wlen = 0, .rlen = 0};
+
+	return (acpi_ec_read_status(ec) & ACPI_EC_FLAG_BURST) ?
+				acpi_ec_transaction(ec, &t) : 0;
+}
+
+static int acpi_ec_read(struct acpi_ec *ec, u8 address, u8 *data)
+{
+	int result;
+	u8 d;
+	struct transaction t = {.command = ACPI_EC_COMMAND_READ,
+				.wdata = &address, .rdata = &d,
+				.wlen = 1, .rlen = 1};
+
+	result = acpi_ec_transaction(ec, &t);
+	*data = d;
+	return result;
+}
+
+static int acpi_ec_write(struct acpi_ec *ec, u8 address, u8 data)
+{
+	u8 wdata[2] = { address, data };
+	struct transaction t = {.command = ACPI_EC_COMMAND_WRITE,
+				.wdata = wdata, .rdata = NULL,
+				.wlen = 2, .rlen = 0};
+
+	return acpi_ec_transaction(ec, &t);
+}
+
+int ec_read(u8 addr, u8 *val)
+{
+	int err;
+	u8 temp_data;
+
+	if (!first_ec)
+		return -ENODEV;
+
+	err = acpi_ec_read(first_ec, addr, &temp_data);
+
+	if (!err) {
+		*val = temp_data;
+		return 0;
+	}
+	return err;
+}
+EXPORT_SYMBOL(ec_read);
+
+int ec_write(u8 addr, u8 val)
+{
+	int err;
+
+	if (!first_ec)
+		return -ENODEV;
+
+	err = acpi_ec_write(first_ec, addr, val);
+
+	return err;
+}
+EXPORT_SYMBOL(ec_write);
+
+int ec_transaction(u8 command,
+		   const u8 *wdata, unsigned wdata_len,
+		   u8 *rdata, unsigned rdata_len)
+{
+	struct transaction t = {.command = command,
+				.wdata = wdata, .rdata = rdata,
+				.wlen = wdata_len, .rlen = rdata_len};
+
+	if (!first_ec)
+		return -ENODEV;
+
+	return acpi_ec_transaction(first_ec, &t);
+}
+EXPORT_SYMBOL(ec_transaction);
+
+/* Get the handle to the EC device */
+acpi_handle ec_get_handle(void)
+{
+	if (!first_ec)
+		return NULL;
+	return first_ec->handle;
+}
+EXPORT_SYMBOL(ec_get_handle);
+
+static void acpi_ec_start(struct acpi_ec *ec, bool resuming)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ec->lock, flags);
+	if (!test_and_set_bit(EC_FLAGS_STARTED, &ec->flags)) {
+		ec_dbg_drv("Starting EC");
+		/* Enable GPE for event processing (SCI_EVT=1) */
+		if (!resuming) {
+			acpi_ec_submit_request(ec);
+			ec_dbg_ref(ec, "Increase driver");
+		}
+		ec_log_drv("EC started");
+	}
+	spin_unlock_irqrestore(&ec->lock, flags);
+}
+
+static bool acpi_ec_stopped(struct acpi_ec *ec)
+{
+	unsigned long flags;
+	bool flushed;
+
+	spin_lock_irqsave(&ec->lock, flags);
+	flushed = acpi_ec_flushed(ec);
+	spin_unlock_irqrestore(&ec->lock, flags);
+	return flushed;
+}
+
+static void acpi_ec_stop(struct acpi_ec *ec, bool suspending)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ec->lock, flags);
+	if (acpi_ec_started(ec)) {
+		ec_dbg_drv("Stopping EC");
+		set_bit(EC_FLAGS_STOPPED, &ec->flags);
+		spin_unlock_irqrestore(&ec->lock, flags);
+		wait_event(ec->wait, acpi_ec_stopped(ec));
+		spin_lock_irqsave(&ec->lock, flags);
+		/* Disable GPE for event processing (SCI_EVT=1) */
+		if (!suspending) {
+			acpi_ec_complete_request(ec);
+			ec_dbg_ref(ec, "Decrease driver");
+		} else if (!ec_freeze_events)
+			__acpi_ec_disable_event(ec);
+		clear_bit(EC_FLAGS_STARTED, &ec->flags);
+		clear_bit(EC_FLAGS_STOPPED, &ec->flags);
+		ec_log_drv("EC stopped");
+	}
+	spin_unlock_irqrestore(&ec->lock, flags);
+}
+
+static void acpi_ec_enter_noirq(struct acpi_ec *ec)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ec->lock, flags);
+	ec->busy_polling = true;
+	ec->polling_guard = 0;
+	ec_log_drv("interrupt blocked");
+	spin_unlock_irqrestore(&ec->lock, flags);
+}
+
+static void acpi_ec_leave_noirq(struct acpi_ec *ec)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ec->lock, flags);
+	ec->busy_polling = ec_busy_polling;
+	ec->polling_guard = ec_polling_guard;
+	ec_log_drv("interrupt unblocked");
+	spin_unlock_irqrestore(&ec->lock, flags);
+}
+
+void acpi_ec_block_transactions(void)
+{
+	struct acpi_ec *ec = first_ec;
+
+	if (!ec)
+		return;
+
+	mutex_lock(&ec->mutex);
+	/* Prevent transactions from being carried out */
+	acpi_ec_stop(ec, true);
+	mutex_unlock(&ec->mutex);
+}
+
+void acpi_ec_unblock_transactions(void)
+{
+	/*
+	 * Allow transactions to happen again (this function is called from
+	 * atomic context during wakeup, so we don't need to acquire the mutex).
+	 */
+	if (first_ec)
+		acpi_ec_start(first_ec, true);
+}
+
+void acpi_ec_mark_gpe_for_wake(void)
+{
+	if (first_ec && !ec_no_wakeup)
+		acpi_mark_gpe_for_wake(NULL, first_ec->gpe);
+}
+
+void acpi_ec_set_gpe_wake_mask(u8 action)
+{
+	if (first_ec && !ec_no_wakeup)
+		acpi_set_gpe_wake_mask(NULL, first_ec->gpe, action);
+}
+
+void acpi_ec_dispatch_gpe(void)
+{
+	if (first_ec)
+		acpi_dispatch_gpe(NULL, first_ec->gpe);
+}
+
+/* --------------------------------------------------------------------------
+                                Event Management
+   -------------------------------------------------------------------------- */
+static struct acpi_ec_query_handler *
+acpi_ec_get_query_handler_by_value(struct acpi_ec *ec, u8 value)
+{
+	struct acpi_ec_query_handler *handler;
+
+	mutex_lock(&ec->mutex);
+	list_for_each_entry(handler, &ec->list, node) {
+		if (value == handler->query_bit) {
+			kref_get(&handler->kref);
+			mutex_unlock(&ec->mutex);
+			return handler;
+		}
+	}
+	mutex_unlock(&ec->mutex);
+	return NULL;
+}
+
+static void acpi_ec_query_handler_release(struct kref *kref)
+{
+	struct acpi_ec_query_handler *handler =
+		container_of(kref, struct acpi_ec_query_handler, kref);
+
+	kfree(handler);
+}
+
+static void acpi_ec_put_query_handler(struct acpi_ec_query_handler *handler)
+{
+	kref_put(&handler->kref, acpi_ec_query_handler_release);
+}
+
+int acpi_ec_add_query_handler(struct acpi_ec *ec, u8 query_bit,
+			      acpi_handle handle, acpi_ec_query_func func,
+			      void *data)
+{
+	struct acpi_ec_query_handler *handler =
+	    kzalloc(sizeof(struct acpi_ec_query_handler), GFP_KERNEL);
+
+	if (!handler)
+		return -ENOMEM;
+
+	handler->query_bit = query_bit;
+	handler->handle = handle;
+	handler->func = func;
+	handler->data = data;
+	mutex_lock(&ec->mutex);
+	kref_init(&handler->kref);
+	list_add(&handler->node, &ec->list);
+	mutex_unlock(&ec->mutex);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(acpi_ec_add_query_handler);
+
+static void acpi_ec_remove_query_handlers(struct acpi_ec *ec,
+					  bool remove_all, u8 query_bit)
+{
+	struct acpi_ec_query_handler *handler, *tmp;
+	LIST_HEAD(free_list);
+
+	mutex_lock(&ec->mutex);
+	list_for_each_entry_safe(handler, tmp, &ec->list, node) {
+		if (remove_all || query_bit == handler->query_bit) {
+			list_del_init(&handler->node);
+			list_add(&handler->node, &free_list);
+		}
+	}
+	mutex_unlock(&ec->mutex);
+	list_for_each_entry_safe(handler, tmp, &free_list, node)
+		acpi_ec_put_query_handler(handler);
+}
+
+void acpi_ec_remove_query_handler(struct acpi_ec *ec, u8 query_bit)
+{
+	acpi_ec_remove_query_handlers(ec, false, query_bit);
+}
+EXPORT_SYMBOL_GPL(acpi_ec_remove_query_handler);
+
+static struct acpi_ec_query *acpi_ec_create_query(u8 *pval)
+{
+	struct acpi_ec_query *q;
+	struct transaction *t;
+
+	q = kzalloc(sizeof (struct acpi_ec_query), GFP_KERNEL);
+	if (!q)
+		return NULL;
+	INIT_WORK(&q->work, acpi_ec_event_processor);
+	t = &q->transaction;
+	t->command = ACPI_EC_COMMAND_QUERY;
+	t->rdata = pval;
+	t->rlen = 1;
+	return q;
+}
+
+static void acpi_ec_delete_query(struct acpi_ec_query *q)
+{
+	if (q) {
+		if (q->handler)
+			acpi_ec_put_query_handler(q->handler);
+		kfree(q);
+	}
+}
+
+static void acpi_ec_event_processor(struct work_struct *work)
+{
+	struct acpi_ec_query *q = container_of(work, struct acpi_ec_query, work);
+	struct acpi_ec_query_handler *handler = q->handler;
+
+	ec_dbg_evt("Query(0x%02x) started", handler->query_bit);
+	if (handler->func)
+		handler->func(handler->data);
+	else if (handler->handle)
+		acpi_evaluate_object(handler->handle, NULL, NULL, NULL);
+	ec_dbg_evt("Query(0x%02x) stopped", handler->query_bit);
+	acpi_ec_delete_query(q);
+}
+
+static int acpi_ec_query(struct acpi_ec *ec, u8 *data)
+{
+	u8 value = 0;
+	int result;
+	struct acpi_ec_query *q;
+
+	q = acpi_ec_create_query(&value);
+	if (!q)
+		return -ENOMEM;
+
+	/*
+	 * Query the EC to find out which _Qxx method we need to evaluate.
+	 * Note that successful completion of the query causes the ACPI_EC_SCI
+	 * bit to be cleared (and thus clearing the interrupt source).
+	 */
+	result = acpi_ec_transaction(ec, &q->transaction);
+	if (!value)
+		result = -ENODATA;
+	if (result)
+		goto err_exit;
+
+	q->handler = acpi_ec_get_query_handler_by_value(ec, value);
+	if (!q->handler) {
+		result = -ENODATA;
+		goto err_exit;
+	}
+
+	/*
+	 * It is reported that _Qxx are evaluated in a parallel way on
+	 * Windows:
+	 * https://bugzilla.kernel.org/show_bug.cgi?id=94411
+	 *
+	 * Put this log entry before schedule_work() in order to make
+	 * it appearing before any other log entries occurred during the
+	 * work queue execution.
+	 */
+	ec_dbg_evt("Query(0x%02x) scheduled", value);
+	if (!queue_work(ec_query_wq, &q->work)) {
+		ec_dbg_evt("Query(0x%02x) overlapped", value);
+		result = -EBUSY;
+	}
+
+err_exit:
+	if (result)
+		acpi_ec_delete_query(q);
+	if (data)
+		*data = value;
+	return result;
+}
+
+static void acpi_ec_check_event(struct acpi_ec *ec)
+{
+	unsigned long flags;
+
+	if (ec_event_clearing == ACPI_EC_EVT_TIMING_EVENT) {
+		if (ec_guard(ec)) {
+			spin_lock_irqsave(&ec->lock, flags);
+			/*
+			 * Take care of the SCI_EVT unless no one else is
+			 * taking care of it.
+			 */
+			if (!ec->curr)
+				advance_transaction(ec);
+			spin_unlock_irqrestore(&ec->lock, flags);
+		}
+	}
+}
+
+static void acpi_ec_event_handler(struct work_struct *work)
+{
+	unsigned long flags;
+	struct acpi_ec *ec = container_of(work, struct acpi_ec, work);
+
+	ec_dbg_evt("Event started");
+
+	spin_lock_irqsave(&ec->lock, flags);
+	while (ec->nr_pending_queries) {
+		spin_unlock_irqrestore(&ec->lock, flags);
+		(void)acpi_ec_query(ec, NULL);
+		spin_lock_irqsave(&ec->lock, flags);
+		ec->nr_pending_queries--;
+		/*
+		 * Before exit, make sure that this work item can be
+		 * scheduled again. There might be QR_EC failures, leaving
+		 * EC_FLAGS_QUERY_PENDING uncleared and preventing this work
+		 * item from being scheduled again.
+		 */
+		if (!ec->nr_pending_queries) {
+			if (ec_event_clearing == ACPI_EC_EVT_TIMING_STATUS ||
+			    ec_event_clearing == ACPI_EC_EVT_TIMING_QUERY)
+				acpi_ec_complete_query(ec);
+		}
+	}
+	spin_unlock_irqrestore(&ec->lock, flags);
+
+	ec_dbg_evt("Event stopped");
+
+	acpi_ec_check_event(ec);
+}
+
+static u32 acpi_ec_gpe_handler(acpi_handle gpe_device,
+	u32 gpe_number, void *data)
+{
+	unsigned long flags;
+	struct acpi_ec *ec = data;
+
+	spin_lock_irqsave(&ec->lock, flags);
+	advance_transaction(ec);
+	spin_unlock_irqrestore(&ec->lock, flags);
+	return ACPI_INTERRUPT_HANDLED;
+}
+
+/* --------------------------------------------------------------------------
+ *                           Address Space Management
+ * -------------------------------------------------------------------------- */
+
+static acpi_status
+acpi_ec_space_handler(u32 function, acpi_physical_address address,
+		      u32 bits, u64 *value64,
+		      void *handler_context, void *region_context)
+{
+	struct acpi_ec *ec = handler_context;
+	int result = 0, i, bytes = bits / 8;
+	u8 *value = (u8 *)value64;
+
+	if ((address > 0xFF) || !value || !handler_context)
+		return AE_BAD_PARAMETER;
+
+	if (function != ACPI_READ && function != ACPI_WRITE)
+		return AE_BAD_PARAMETER;
+
+	if (ec->busy_polling || bits > 8)
+		acpi_ec_burst_enable(ec);
+
+	for (i = 0; i < bytes; ++i, ++address, ++value)
+		result = (function == ACPI_READ) ?
+			acpi_ec_read(ec, address, value) :
+			acpi_ec_write(ec, address, *value);
+
+	if (ec->busy_polling || bits > 8)
+		acpi_ec_burst_disable(ec);
+
+	switch (result) {
+	case -EINVAL:
+		return AE_BAD_PARAMETER;
+	case -ENODEV:
+		return AE_NOT_FOUND;
+	case -ETIME:
+		return AE_TIME;
+	default:
+		return AE_OK;
+	}
+}
+
+/* --------------------------------------------------------------------------
+ *                             Driver Interface
+ * -------------------------------------------------------------------------- */
+
+static acpi_status
+ec_parse_io_ports(struct acpi_resource *resource, void *context);
+
+static void acpi_ec_free(struct acpi_ec *ec)
+{
+	if (first_ec == ec)
+		first_ec = NULL;
+	if (boot_ec == ec)
+		boot_ec = NULL;
+	kfree(ec);
+}
+
+static struct acpi_ec *acpi_ec_alloc(void)
+{
+	struct acpi_ec *ec = kzalloc(sizeof(struct acpi_ec), GFP_KERNEL);
+
+	if (!ec)
+		return NULL;
+	mutex_init(&ec->mutex);
+	init_waitqueue_head(&ec->wait);
+	INIT_LIST_HEAD(&ec->list);
+	spin_lock_init(&ec->lock);
+	INIT_WORK(&ec->work, acpi_ec_event_handler);
+	ec->timestamp = jiffies;
+	ec->busy_polling = true;
+	ec->polling_guard = 0;
+	return ec;
+}
+
+static acpi_status
+acpi_ec_register_query_methods(acpi_handle handle, u32 level,
+			       void *context, void **return_value)
+{
+	char node_name[5];
+	struct acpi_buffer buffer = { sizeof(node_name), node_name };
+	struct acpi_ec *ec = context;
+	int value = 0;
+	acpi_status status;
+
+	status = acpi_get_name(handle, ACPI_SINGLE_NAME, &buffer);
+
+	if (ACPI_SUCCESS(status) && sscanf(node_name, "_Q%x", &value) == 1)
+		acpi_ec_add_query_handler(ec, value, handle, NULL, NULL);
+	return AE_OK;
+}
+
+static acpi_status
+ec_parse_device(acpi_handle handle, u32 Level, void *context, void **retval)
+{
+	acpi_status status;
+	unsigned long long tmp = 0;
+	struct acpi_ec *ec = context;
+
+	/* clear addr values, ec_parse_io_ports depend on it */
+	ec->command_addr = ec->data_addr = 0;
+
+	status = acpi_walk_resources(handle, METHOD_NAME__CRS,
+				     ec_parse_io_ports, ec);
+	if (ACPI_FAILURE(status))
+		return status;
+	if (ec->data_addr == 0 || ec->command_addr == 0)
+		return AE_OK;
+
+	if (boot_ec && boot_ec_is_ecdt && EC_FLAGS_IGNORE_DSDT_GPE) {
+		/*
+		 * Always inherit the GPE number setting from the ECDT
+		 * EC.
+		 */
+		ec->gpe = boot_ec->gpe;
+	} else {
+		/* Get GPE bit assignment (EC events). */
+		/* TODO: Add support for _GPE returning a package */
+		status = acpi_evaluate_integer(handle, "_GPE", NULL, &tmp);
+		if (ACPI_FAILURE(status))
+			return status;
+		ec->gpe = tmp;
+	}
+	/* Use the global lock for all EC transactions? */
+	tmp = 0;
+	acpi_evaluate_integer(handle, "_GLK", NULL, &tmp);
+	ec->global_lock = tmp;
+	ec->handle = handle;
+	return AE_CTRL_TERMINATE;
+}
+
+/*
+ * Note: This function returns an error code only when the address space
+ *       handler is not installed, which means "not able to handle
+ *       transactions".
+ */
+static int ec_install_handlers(struct acpi_ec *ec, bool handle_events)
+{
+	acpi_status status;
+
+	acpi_ec_start(ec, false);
+
+	if (!test_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags)) {
+		acpi_ec_enter_noirq(ec);
+		status = acpi_install_address_space_handler(ec->handle,
+							    ACPI_ADR_SPACE_EC,
+							    &acpi_ec_space_handler,
+							    NULL, ec);
+		if (ACPI_FAILURE(status)) {
+			if (status == AE_NOT_FOUND) {
+				/*
+				 * Maybe OS fails in evaluating the _REG
+				 * object. The AE_NOT_FOUND error will be
+				 * ignored and OS * continue to initialize
+				 * EC.
+				 */
+				pr_err("Fail in evaluating the _REG object"
+					" of EC device. Broken bios is suspected.\n");
+			} else {
+				acpi_ec_stop(ec, false);
+				return -ENODEV;
+			}
+		}
+		set_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags);
+	}
+
+	if (!handle_events)
+		return 0;
+
+	if (!test_bit(EC_FLAGS_EVT_HANDLER_INSTALLED, &ec->flags)) {
+		/* Find and register all query methods */
+		acpi_walk_namespace(ACPI_TYPE_METHOD, ec->handle, 1,
+				    acpi_ec_register_query_methods,
+				    NULL, ec, NULL);
+		set_bit(EC_FLAGS_EVT_HANDLER_INSTALLED, &ec->flags);
+	}
+	if (!test_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags)) {
+		status = acpi_install_gpe_raw_handler(NULL, ec->gpe,
+					  ACPI_GPE_EDGE_TRIGGERED,
+					  &acpi_ec_gpe_handler, ec);
+		/* This is not fatal as we can poll EC events */
+		if (ACPI_SUCCESS(status)) {
+			set_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags);
+			acpi_ec_leave_noirq(ec);
+			if (test_bit(EC_FLAGS_STARTED, &ec->flags) &&
+			    ec->reference_count >= 1)
+				acpi_ec_enable_gpe(ec, true);
+		}
+	}
+	/* EC is fully operational, allow queries */
+	acpi_ec_enable_event(ec);
+
+	return 0;
+}
+
+static void ec_remove_handlers(struct acpi_ec *ec)
+{
+	if (test_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags)) {
+		if (ACPI_FAILURE(acpi_remove_address_space_handler(ec->handle,
+					ACPI_ADR_SPACE_EC, &acpi_ec_space_handler)))
+			pr_err("failed to remove space handler\n");
+		clear_bit(EC_FLAGS_EC_HANDLER_INSTALLED, &ec->flags);
+	}
+
+	/*
+	 * Stops handling the EC transactions after removing the operation
+	 * region handler. This is required because _REG(DISCONNECT)
+	 * invoked during the removal can result in new EC transactions.
+	 *
+	 * Flushes the EC requests and thus disables the GPE before
+	 * removing the GPE handler. This is required by the current ACPICA
+	 * GPE core. ACPICA GPE core will automatically disable a GPE when
+	 * it is indicated but there is no way to handle it. So the drivers
+	 * must disable the GPEs prior to removing the GPE handlers.
+	 */
+	acpi_ec_stop(ec, false);
+
+	if (test_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags)) {
+		if (ACPI_FAILURE(acpi_remove_gpe_handler(NULL, ec->gpe,
+					&acpi_ec_gpe_handler)))
+			pr_err("failed to remove gpe handler\n");
+		clear_bit(EC_FLAGS_GPE_HANDLER_INSTALLED, &ec->flags);
+	}
+	if (test_bit(EC_FLAGS_EVT_HANDLER_INSTALLED, &ec->flags)) {
+		acpi_ec_remove_query_handlers(ec, true, 0);
+		clear_bit(EC_FLAGS_EVT_HANDLER_INSTALLED, &ec->flags);
+	}
+}
+
+static int acpi_ec_setup(struct acpi_ec *ec, bool handle_events)
+{
+	int ret;
+
+	ret = ec_install_handlers(ec, handle_events);
+	if (ret)
+		return ret;
+
+	/* First EC capable of handling transactions */
+	if (!first_ec) {
+		first_ec = ec;
+		acpi_handle_info(first_ec->handle, "Used as first EC\n");
+	}
+
+	acpi_handle_info(ec->handle,
+			 "GPE=0x%x, EC_CMD/EC_SC=0x%lx, EC_DATA=0x%lx\n",
+			 ec->gpe, ec->command_addr, ec->data_addr);
+	return ret;
+}
+
+static int acpi_config_boot_ec(struct acpi_ec *ec, acpi_handle handle,
+			       bool handle_events, bool is_ecdt)
+{
+	int ret;
+
+	/*
+	 * Changing the ACPI handle results in a re-configuration of the
+	 * boot EC. And if it happens after the namespace initialization,
+	 * it causes _REG evaluations.
+	 */
+	if (boot_ec && boot_ec->handle != handle)
+		ec_remove_handlers(boot_ec);
+
+	/* Unset old boot EC */
+	if (boot_ec != ec)
+		acpi_ec_free(boot_ec);
+
+	/*
+	 * ECDT device creation is split into acpi_ec_ecdt_probe() and
+	 * acpi_ec_ecdt_start(). This function takes care of completing the
+	 * ECDT parsing logic as the handle update should be performed
+	 * between the installation/uninstallation of the handlers.
+	 */
+	if (ec->handle != handle)
+		ec->handle = handle;
+
+	ret = acpi_ec_setup(ec, handle_events);
+	if (ret)
+		return ret;
+
+	/* Set new boot EC */
+	if (!boot_ec) {
+		boot_ec = ec;
+		boot_ec_is_ecdt = is_ecdt;
+	}
+
+	acpi_handle_info(boot_ec->handle,
+			 "Used as boot %s EC to handle transactions%s\n",
+			 is_ecdt ? "ECDT" : "DSDT",
+			 handle_events ? " and events" : "");
+	return ret;
+}
+
+static bool acpi_ec_ecdt_get_handle(acpi_handle *phandle)
+{
+	struct acpi_table_ecdt *ecdt_ptr;
+	acpi_status status;
+	acpi_handle handle;
+
+	status = acpi_get_table(ACPI_SIG_ECDT, 1,
+				(struct acpi_table_header **)&ecdt_ptr);
+	if (ACPI_FAILURE(status))
+		return false;
+
+	status = acpi_get_handle(NULL, ecdt_ptr->id, &handle);
+	if (ACPI_FAILURE(status))
+		return false;
+
+	*phandle = handle;
+	return true;
+}
+
+static bool acpi_is_boot_ec(struct acpi_ec *ec)
+{
+	if (!boot_ec)
+		return false;
+	if (ec->command_addr == boot_ec->command_addr &&
+	    ec->data_addr == boot_ec->data_addr)
+		return true;
+	return false;
+}
+
+static int acpi_ec_add(struct acpi_device *device)
+{
+	struct acpi_ec *ec = NULL;
+	int ret;
+	bool is_ecdt = false;
+	acpi_status status;
+
+	strcpy(acpi_device_name(device), ACPI_EC_DEVICE_NAME);
+	strcpy(acpi_device_class(device), ACPI_EC_CLASS);
+
+	if (!strcmp(acpi_device_hid(device), ACPI_ECDT_HID)) {
+		is_ecdt = true;
+		ec = boot_ec;
+	} else {
+		ec = acpi_ec_alloc();
+		if (!ec)
+			return -ENOMEM;
+		status = ec_parse_device(device->handle, 0, ec, NULL);
+		if (status != AE_CTRL_TERMINATE) {
+			ret = -EINVAL;
+			goto err_alloc;
+		}
+	}
+
+	if (acpi_is_boot_ec(ec)) {
+		boot_ec_is_ecdt = is_ecdt;
+		if (!is_ecdt) {
+			/*
+			 * Trust PNP0C09 namespace location rather than
+			 * ECDT ID. But trust ECDT GPE rather than _GPE
+			 * because of ASUS quirks, so do not change
+			 * boot_ec->gpe to ec->gpe.
+			 */
+			boot_ec->handle = ec->handle;
+			acpi_handle_debug(ec->handle, "duplicated.\n");
+			acpi_ec_free(ec);
+			ec = boot_ec;
+		}
+		ret = acpi_config_boot_ec(ec, ec->handle, true, is_ecdt);
+	} else
+		ret = acpi_ec_setup(ec, true);
+	if (ret)
+		goto err_query;
+
+	device->driver_data = ec;
+
+	ret = !!request_region(ec->data_addr, 1, "EC data");
+	WARN(!ret, "Could not request EC data io port 0x%lx", ec->data_addr);
+	ret = !!request_region(ec->command_addr, 1, "EC cmd");
+	WARN(!ret, "Could not request EC cmd io port 0x%lx", ec->command_addr);
+
+	if (!is_ecdt) {
+		/* Reprobe devices depending on the EC */
+		acpi_walk_dep_device_list(ec->handle);
+	}
+	acpi_handle_debug(ec->handle, "enumerated.\n");
+	return 0;
+
+err_query:
+	if (ec != boot_ec)
+		acpi_ec_remove_query_handlers(ec, true, 0);
+err_alloc:
+	if (ec != boot_ec)
+		acpi_ec_free(ec);
+	return ret;
+}
+
+static int acpi_ec_remove(struct acpi_device *device)
+{
+	struct acpi_ec *ec;
+
+	if (!device)
+		return -EINVAL;
+
+	ec = acpi_driver_data(device);
+	release_region(ec->data_addr, 1);
+	release_region(ec->command_addr, 1);
+	device->driver_data = NULL;
+	if (ec != boot_ec) {
+		ec_remove_handlers(ec);
+		acpi_ec_free(ec);
+	}
+	return 0;
+}
+
+static acpi_status
+ec_parse_io_ports(struct acpi_resource *resource, void *context)
+{
+	struct acpi_ec *ec = context;
+
+	if (resource->type != ACPI_RESOURCE_TYPE_IO)
+		return AE_OK;
+
+	/*
+	 * The first address region returned is the data port, and
+	 * the second address region returned is the status/command
+	 * port.
+	 */
+	if (ec->data_addr == 0)
+		ec->data_addr = resource->data.io.minimum;
+	else if (ec->command_addr == 0)
+		ec->command_addr = resource->data.io.minimum;
+	else
+		return AE_CTRL_TERMINATE;
+
+	return AE_OK;
+}
+
+static const struct acpi_device_id ec_device_ids[] = {
+	{"PNP0C09", 0},
+	{ACPI_ECDT_HID, 0},
+	{"", 0},
+};
+
+/*
+ * This function is not Windows-compatible as Windows never enumerates the
+ * namespace EC before the main ACPI device enumeration process. It is
+ * retained for historical reason and will be deprecated in the future.
+ */
+int __init acpi_ec_dsdt_probe(void)
+{
+	acpi_status status;
+	struct acpi_ec *ec;
+	int ret;
+
+	/*
+	 * If a platform has ECDT, there is no need to proceed as the
+	 * following probe is not a part of the ACPI device enumeration,
+	 * executing _STA is not safe, and thus this probe may risk of
+	 * picking up an invalid EC device.
+	 */
+	if (boot_ec)
+		return -ENODEV;
+
+	ec = acpi_ec_alloc();
+	if (!ec)
+		return -ENOMEM;
+	/*
+	 * At this point, the namespace is initialized, so start to find
+	 * the namespace objects.
+	 */
+	status = acpi_get_devices(ec_device_ids[0].id,
+				  ec_parse_device, ec, NULL);
+	if (ACPI_FAILURE(status) || !ec->handle) {
+		ret = -ENODEV;
+		goto error;
+	}
+	/*
+	 * When the DSDT EC is available, always re-configure boot EC to
+	 * have _REG evaluated. _REG can only be evaluated after the
+	 * namespace initialization.
+	 * At this point, the GPE is not fully initialized, so do not to
+	 * handle the events.
+	 */
+	ret = acpi_config_boot_ec(ec, ec->handle, false, false);
+error:
+	if (ret)
+		acpi_ec_free(ec);
+	return ret;
+}
+
+/*
+ * If the DSDT EC is not functioning, we still need to prepare a fully
+ * functioning ECDT EC first in order to handle the events.
+ * https://bugzilla.kernel.org/show_bug.cgi?id=115021
+ */
+static int __init acpi_ec_ecdt_start(void)
+{
+	acpi_handle handle;
+
+	if (!boot_ec)
+		return -ENODEV;
+	/* In case acpi_ec_ecdt_start() is called after acpi_ec_add() */
+	if (!boot_ec_is_ecdt)
+		return -ENODEV;
+
+	/*
+	 * At this point, the namespace and the GPE is initialized, so
+	 * start to find the namespace objects and handle the events.
+	 *
+	 * Note: ec->handle can be valid if this function is called after
+	 * acpi_ec_add(), hence the fast path.
+	 */
+	if (boot_ec->handle == ACPI_ROOT_OBJECT) {
+		if (!acpi_ec_ecdt_get_handle(&handle))
+			return -ENODEV;
+		boot_ec->handle = handle;
+	}
+
+	/* Register to ACPI bus with PM ops attached */
+	return acpi_bus_register_early_device(ACPI_BUS_TYPE_ECDT_EC);
+}
+
+#if 0
+/*
+ * Some EC firmware variations refuses to respond QR_EC when SCI_EVT is not
+ * set, for which case, we complete the QR_EC without issuing it to the
+ * firmware.
+ * https://bugzilla.kernel.org/show_bug.cgi?id=82611
+ * https://bugzilla.kernel.org/show_bug.cgi?id=97381
+ */
+static int ec_flag_query_handshake(const struct dmi_system_id *id)
+{
+	pr_debug("Detected the EC firmware requiring QR_EC issued when SCI_EVT set\n");
+	EC_FLAGS_QUERY_HANDSHAKE = 1;
+	return 0;
+}
+#endif
+
+/*
+ * On some hardware it is necessary to clear events accumulated by the EC during
+ * sleep. These ECs stop reporting GPEs until they are manually polled, if too
+ * many events are accumulated. (e.g. Samsung Series 5/9 notebooks)
+ *
+ * https://bugzilla.kernel.org/show_bug.cgi?id=44161
+ *
+ * Ideally, the EC should also be instructed NOT to accumulate events during
+ * sleep (which Windows seems to do somehow), but the interface to control this
+ * behaviour is not known at this time.
+ *
+ * Models known to be affected are Samsung 530Uxx/535Uxx/540Uxx/550Pxx/900Xxx,
+ * however it is very likely that other Samsung models are affected.
+ *
+ * On systems which don't accumulate _Q events during sleep, this extra check
+ * should be harmless.
+ */
+static int ec_clear_on_resume(const struct dmi_system_id *id)
+{
+	pr_debug("Detected system needing EC poll on resume.\n");
+	EC_FLAGS_CLEAR_ON_RESUME = 1;
+	ec_event_clearing = ACPI_EC_EVT_TIMING_STATUS;
+	return 0;
+}
+
+/*
+ * Some ECDTs contain wrong register addresses.
+ * MSI MS-171F
+ * https://bugzilla.kernel.org/show_bug.cgi?id=12461
+ */
+static int ec_correct_ecdt(const struct dmi_system_id *id)
+{
+	pr_debug("Detected system needing ECDT address correction.\n");
+	EC_FLAGS_CORRECT_ECDT = 1;
+	return 0;
+}
+
+/*
+ * Some DSDTs contain wrong GPE setting.
+ * Asus FX502VD/VE, GL702VMK, X550VXK, X580VD
+ * https://bugzilla.kernel.org/show_bug.cgi?id=195651
+ */
+static int ec_honor_ecdt_gpe(const struct dmi_system_id *id)
+{
+	pr_debug("Detected system needing ignore DSDT GPE setting.\n");
+	EC_FLAGS_IGNORE_DSDT_GPE = 1;
+	return 0;
+}
+
+static const struct dmi_system_id ec_dmi_table[] __initconst = {
+	{
+	ec_correct_ecdt, "MSI MS-171F", {
+	DMI_MATCH(DMI_SYS_VENDOR, "Micro-Star"),
+	DMI_MATCH(DMI_PRODUCT_NAME, "MS-171F"),}, NULL},
+	{
+	ec_honor_ecdt_gpe, "ASUS FX502VD", {
+	DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
+	DMI_MATCH(DMI_PRODUCT_NAME, "FX502VD"),}, NULL},
+	{
+	ec_honor_ecdt_gpe, "ASUS FX502VE", {
+	DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
+	DMI_MATCH(DMI_PRODUCT_NAME, "FX502VE"),}, NULL},
+	{
+	ec_honor_ecdt_gpe, "ASUS GL702VMK", {
+	DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
+	DMI_MATCH(DMI_PRODUCT_NAME, "GL702VMK"),}, NULL},
+	{
+	ec_honor_ecdt_gpe, "ASUSTeK COMPUTER INC. X505BA", {
+	DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
+	DMI_MATCH(DMI_PRODUCT_NAME, "X505BA"),}, NULL},
+	{
+	ec_honor_ecdt_gpe, "ASUSTeK COMPUTER INC. X505BP", {
+	DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
+	DMI_MATCH(DMI_PRODUCT_NAME, "X505BP"),}, NULL},
+	{
+	ec_honor_ecdt_gpe, "ASUSTeK COMPUTER INC. X542BA", {
+	DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
+	DMI_MATCH(DMI_PRODUCT_NAME, "X542BA"),}, NULL},
+	{
+	ec_honor_ecdt_gpe, "ASUSTeK COMPUTER INC. X542BP", {
+	DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
+	DMI_MATCH(DMI_PRODUCT_NAME, "X542BP"),}, NULL},
+	{
+	ec_honor_ecdt_gpe, "ASUS X550VXK", {
+	DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
+	DMI_MATCH(DMI_PRODUCT_NAME, "X550VXK"),}, NULL},
+	{
+	ec_honor_ecdt_gpe, "ASUS X580VD", {
+	DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
+	DMI_MATCH(DMI_PRODUCT_NAME, "X580VD"),}, NULL},
+	{
+	ec_clear_on_resume, "Samsung hardware", {
+	DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD.")}, NULL},
+	{},
+};
+
+int __init acpi_ec_ecdt_probe(void)
+{
+	int ret;
+	acpi_status status;
+	struct acpi_table_ecdt *ecdt_ptr;
+	struct acpi_ec *ec;
+
+	ec = acpi_ec_alloc();
+	if (!ec)
+		return -ENOMEM;
+	/*
+	 * Generate a boot ec context
+	 */
+	dmi_check_system(ec_dmi_table);
+	status = acpi_get_table(ACPI_SIG_ECDT, 1,
+				(struct acpi_table_header **)&ecdt_ptr);
+	if (ACPI_FAILURE(status)) {
+		ret = -ENODEV;
+		goto error;
+	}
+
+	if (!ecdt_ptr->control.address || !ecdt_ptr->data.address) {
+		/*
+		 * Asus X50GL:
+		 * https://bugzilla.kernel.org/show_bug.cgi?id=11880
+		 */
+		ret = -ENODEV;
+		goto error;
+	}
+
+	if (EC_FLAGS_CORRECT_ECDT) {
+		ec->command_addr = ecdt_ptr->data.address;
+		ec->data_addr = ecdt_ptr->control.address;
+	} else {
+		ec->command_addr = ecdt_ptr->control.address;
+		ec->data_addr = ecdt_ptr->data.address;
+	}
+	ec->gpe = ecdt_ptr->gpe;
+
+	/*
+	 * At this point, the namespace is not initialized, so do not find
+	 * the namespace objects, or handle the events.
+	 */
+	ret = acpi_config_boot_ec(ec, ACPI_ROOT_OBJECT, false, true);
+error:
+	if (ret)
+		acpi_ec_free(ec);
+	return ret;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int acpi_ec_suspend(struct device *dev)
+{
+	struct acpi_ec *ec =
+		acpi_driver_data(to_acpi_device(dev));
+
+	if (acpi_sleep_no_ec_events() && ec_freeze_events)
+		acpi_ec_disable_event(ec);
+	return 0;
+}
+
+static int acpi_ec_suspend_noirq(struct device *dev)
+{
+	struct acpi_ec *ec = acpi_driver_data(to_acpi_device(dev));
+
+	/*
+	 * The SCI handler doesn't run at this point, so the GPE can be
+	 * masked at the low level without side effects.
+	 */
+	if (ec_no_wakeup && test_bit(EC_FLAGS_STARTED, &ec->flags) &&
+	    ec->reference_count >= 1)
+		acpi_set_gpe(NULL, ec->gpe, ACPI_GPE_DISABLE);
+
+	if (acpi_sleep_no_ec_events())
+		acpi_ec_enter_noirq(ec);
+
+	return 0;
+}
+
+static int acpi_ec_resume_noirq(struct device *dev)
+{
+	struct acpi_ec *ec = acpi_driver_data(to_acpi_device(dev));
+
+	if (acpi_sleep_no_ec_events())
+		acpi_ec_leave_noirq(ec);
+
+	if (ec_no_wakeup && test_bit(EC_FLAGS_STARTED, &ec->flags) &&
+	    ec->reference_count >= 1)
+		acpi_set_gpe(NULL, ec->gpe, ACPI_GPE_ENABLE);
+
+	return 0;
+}
+
+static int acpi_ec_resume(struct device *dev)
+{
+	struct acpi_ec *ec =
+		acpi_driver_data(to_acpi_device(dev));
+
+	acpi_ec_enable_event(ec);
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops acpi_ec_pm = {
+	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(acpi_ec_suspend_noirq, acpi_ec_resume_noirq)
+	SET_SYSTEM_SLEEP_PM_OPS(acpi_ec_suspend, acpi_ec_resume)
+};
+
+static int param_set_event_clearing(const char *val,
+				    const struct kernel_param *kp)
+{
+	int result = 0;
+
+	if (!strncmp(val, "status", sizeof("status") - 1)) {
+		ec_event_clearing = ACPI_EC_EVT_TIMING_STATUS;
+		pr_info("Assuming SCI_EVT clearing on EC_SC accesses\n");
+	} else if (!strncmp(val, "query", sizeof("query") - 1)) {
+		ec_event_clearing = ACPI_EC_EVT_TIMING_QUERY;
+		pr_info("Assuming SCI_EVT clearing on QR_EC writes\n");
+	} else if (!strncmp(val, "event", sizeof("event") - 1)) {
+		ec_event_clearing = ACPI_EC_EVT_TIMING_EVENT;
+		pr_info("Assuming SCI_EVT clearing on event reads\n");
+	} else
+		result = -EINVAL;
+	return result;
+}
+
+static int param_get_event_clearing(char *buffer,
+				    const struct kernel_param *kp)
+{
+	switch (ec_event_clearing) {
+	case ACPI_EC_EVT_TIMING_STATUS:
+		return sprintf(buffer, "status");
+	case ACPI_EC_EVT_TIMING_QUERY:
+		return sprintf(buffer, "query");
+	case ACPI_EC_EVT_TIMING_EVENT:
+		return sprintf(buffer, "event");
+	default:
+		return sprintf(buffer, "invalid");
+	}
+	return 0;
+}
+
+module_param_call(ec_event_clearing, param_set_event_clearing, param_get_event_clearing,
+		  NULL, 0644);
+MODULE_PARM_DESC(ec_event_clearing, "Assumed SCI_EVT clearing timing");
+
+static struct acpi_driver acpi_ec_driver = {
+	.name = "ec",
+	.class = ACPI_EC_CLASS,
+	.ids = ec_device_ids,
+	.ops = {
+		.add = acpi_ec_add,
+		.remove = acpi_ec_remove,
+		},
+	.drv.pm = &acpi_ec_pm,
+};
+
+static inline int acpi_ec_query_init(void)
+{
+	if (!ec_query_wq) {
+		ec_query_wq = alloc_workqueue("kec_query", 0,
+					      ec_max_queries);
+		if (!ec_query_wq)
+			return -ENODEV;
+	}
+	return 0;
+}
+
+static inline void acpi_ec_query_exit(void)
+{
+	if (ec_query_wq) {
+		destroy_workqueue(ec_query_wq);
+		ec_query_wq = NULL;
+	}
+}
+
+static const struct dmi_system_id acpi_ec_no_wakeup[] = {
+	{
+		.ident = "Thinkpad X1 Carbon 6th",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+			DMI_MATCH(DMI_PRODUCT_FAMILY, "Thinkpad X1 Carbon 6th"),
+		},
+	},
+	{
+		.ident = "ThinkPad X1 Carbon 6th",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+			DMI_MATCH(DMI_PRODUCT_FAMILY, "ThinkPad X1 Carbon 6th"),
+		},
+	},
+	{
+		.ident = "ThinkPad X1 Yoga 3rd",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+			DMI_MATCH(DMI_PRODUCT_FAMILY, "ThinkPad X1 Yoga 3rd"),
+		},
+	},
+	{ },
+};
+
+int __init acpi_ec_init(void)
+{
+	int result;
+	int ecdt_fail, dsdt_fail;
+
+	/* register workqueue for _Qxx evaluations */
+	result = acpi_ec_query_init();
+	if (result)
+		return result;
+
+	/*
+	 * Disable EC wakeup on following systems to prevent periodic
+	 * wakeup from EC GPE.
+	 */
+	if (dmi_check_system(acpi_ec_no_wakeup)) {
+		ec_no_wakeup = true;
+		pr_debug("Disabling EC wakeup on suspend-to-idle\n");
+	}
+
+	/* Drivers must be started after acpi_ec_query_init() */
+	dsdt_fail = acpi_bus_register_driver(&acpi_ec_driver);
+	/*
+	 * Register ECDT to ACPI bus only when PNP0C09 probe fails. This is
+	 * useful for platforms (confirmed on ASUS X550ZE) with valid ECDT
+	 * settings but invalid DSDT settings.
+	 * https://bugzilla.kernel.org/show_bug.cgi?id=196847
+	 */
+	ecdt_fail = acpi_ec_ecdt_start();
+	return ecdt_fail && dsdt_fail ? -ENODEV : 0;
+}
+
+/* EC driver currently not unloadable */
+#if 0
+static void __exit acpi_ec_exit(void)
+{
+
+	acpi_bus_unregister_driver(&acpi_ec_driver);
+	acpi_ec_query_exit();
+}
+#endif	/* 0 */