xref: /openbmc/linux/drivers/acpi/ec.c (revision 976fa9a3)
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  *  You should have received a copy of the GNU General Public License along
26  *  with this program; if not, write to the Free Software Foundation, Inc.,
27  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
28  *
29  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
30  */
31 
32 /* Uncomment next line to get verbose printout */
33 /* #define DEBUG */
34 #define pr_fmt(fmt) "ACPI : EC: " fmt
35 
36 #include <linux/kernel.h>
37 #include <linux/module.h>
38 #include <linux/init.h>
39 #include <linux/types.h>
40 #include <linux/delay.h>
41 #include <linux/interrupt.h>
42 #include <linux/list.h>
43 #include <linux/spinlock.h>
44 #include <linux/slab.h>
45 #include <linux/acpi.h>
46 #include <linux/dmi.h>
47 #include <asm/io.h>
48 
49 #include "internal.h"
50 
51 #define ACPI_EC_CLASS			"embedded_controller"
52 #define ACPI_EC_DEVICE_NAME		"Embedded Controller"
53 #define ACPI_EC_FILE_INFO		"info"
54 
55 /* EC status register */
56 #define ACPI_EC_FLAG_OBF	0x01	/* Output buffer full */
57 #define ACPI_EC_FLAG_IBF	0x02	/* Input buffer full */
58 #define ACPI_EC_FLAG_CMD	0x08	/* Input buffer contains a command */
59 #define ACPI_EC_FLAG_BURST	0x10	/* burst mode */
60 #define ACPI_EC_FLAG_SCI	0x20	/* EC-SCI occurred */
61 
62 /* EC commands */
63 enum ec_command {
64 	ACPI_EC_COMMAND_READ = 0x80,
65 	ACPI_EC_COMMAND_WRITE = 0x81,
66 	ACPI_EC_BURST_ENABLE = 0x82,
67 	ACPI_EC_BURST_DISABLE = 0x83,
68 	ACPI_EC_COMMAND_QUERY = 0x84,
69 };
70 
71 #define ACPI_EC_DELAY		500	/* Wait 500ms max. during EC ops */
72 #define ACPI_EC_UDELAY_GLK	1000	/* Wait 1ms max. to get global lock */
73 #define ACPI_EC_MSI_UDELAY	550	/* Wait 550us for MSI EC */
74 #define ACPI_EC_UDELAY_POLL	1000	/* Wait 1ms for EC transaction polling */
75 #define ACPI_EC_CLEAR_MAX	100	/* Maximum number of events to query
76 					 * when trying to clear the EC */
77 
78 enum {
79 	EC_FLAGS_QUERY_PENDING,		/* Query is pending */
80 	EC_FLAGS_HANDLERS_INSTALLED,	/* Handlers for GPE and
81 					 * OpReg are installed */
82 	EC_FLAGS_STARTED,		/* Driver is started */
83 	EC_FLAGS_STOPPED,		/* Driver is stopped */
84 	EC_FLAGS_COMMAND_STORM,		/* GPE storms occurred to the
85 					 * current command processing */
86 };
87 
88 #define ACPI_EC_COMMAND_POLL		0x01 /* Available for command byte */
89 #define ACPI_EC_COMMAND_COMPLETE	0x02 /* Completed last byte */
90 
91 /* ec.c is compiled in acpi namespace so this shows up as acpi.ec_delay param */
92 static unsigned int ec_delay __read_mostly = ACPI_EC_DELAY;
93 module_param(ec_delay, uint, 0644);
94 MODULE_PARM_DESC(ec_delay, "Timeout(ms) waited until an EC command completes");
95 
96 /*
97  * If the number of false interrupts per one transaction exceeds
98  * this threshold, will think there is a GPE storm happened and
99  * will disable the GPE for normal transaction.
100  */
101 static unsigned int ec_storm_threshold  __read_mostly = 8;
102 module_param(ec_storm_threshold, uint, 0644);
103 MODULE_PARM_DESC(ec_storm_threshold, "Maxim false GPE numbers not considered as GPE storm");
104 
105 struct acpi_ec_query_handler {
106 	struct list_head node;
107 	acpi_ec_query_func func;
108 	acpi_handle handle;
109 	void *data;
110 	u8 query_bit;
111 	struct kref kref;
112 };
113 
114 struct transaction {
115 	const u8 *wdata;
116 	u8 *rdata;
117 	unsigned short irq_count;
118 	u8 command;
119 	u8 wi;
120 	u8 ri;
121 	u8 wlen;
122 	u8 rlen;
123 	u8 flags;
124 	unsigned long timestamp;
125 };
126 
127 static int acpi_ec_query(struct acpi_ec *ec, u8 *data);
128 static void advance_transaction(struct acpi_ec *ec);
129 
130 struct acpi_ec *boot_ec, *first_ec;
131 EXPORT_SYMBOL(first_ec);
132 
133 static int EC_FLAGS_MSI; /* Out-of-spec MSI controller */
134 static int EC_FLAGS_VALIDATE_ECDT; /* ASUStec ECDTs need to be validated */
135 static int EC_FLAGS_SKIP_DSDT_SCAN; /* Not all BIOS survive early DSDT scan */
136 static int EC_FLAGS_CLEAR_ON_RESUME; /* Needs acpi_ec_clear() on boot/resume */
137 static int EC_FLAGS_QUERY_HANDSHAKE; /* Needs QR_EC issued when SCI_EVT set */
138 
139 /* --------------------------------------------------------------------------
140  *                           Logging/Debugging
141  * -------------------------------------------------------------------------- */
142 
143 /*
144  * Splitters used by the developers to track the boundary of the EC
145  * handling processes.
146  */
147 #ifdef DEBUG
148 #define EC_DBG_SEP	" "
149 #define EC_DBG_DRV	"+++++"
150 #define EC_DBG_STM	"====="
151 #define EC_DBG_REQ	"*****"
152 #define EC_DBG_EVT	"#####"
153 #else
154 #define EC_DBG_SEP	""
155 #define EC_DBG_DRV
156 #define EC_DBG_STM
157 #define EC_DBG_REQ
158 #define EC_DBG_EVT
159 #endif
160 
161 #define ec_log_raw(fmt, ...) \
162 	pr_info(fmt "\n", ##__VA_ARGS__)
163 #define ec_dbg_raw(fmt, ...) \
164 	pr_debug(fmt "\n", ##__VA_ARGS__)
165 #define ec_log(filter, fmt, ...) \
166 	ec_log_raw(filter EC_DBG_SEP fmt EC_DBG_SEP filter, ##__VA_ARGS__)
167 #define ec_dbg(filter, fmt, ...) \
168 	ec_dbg_raw(filter EC_DBG_SEP fmt EC_DBG_SEP filter, ##__VA_ARGS__)
169 
170 #define ec_log_drv(fmt, ...) \
171 	ec_log(EC_DBG_DRV, fmt, ##__VA_ARGS__)
172 #define ec_dbg_drv(fmt, ...) \
173 	ec_dbg(EC_DBG_DRV, fmt, ##__VA_ARGS__)
174 #define ec_dbg_stm(fmt, ...) \
175 	ec_dbg(EC_DBG_STM, fmt, ##__VA_ARGS__)
176 #define ec_dbg_req(fmt, ...) \
177 	ec_dbg(EC_DBG_REQ, fmt, ##__VA_ARGS__)
178 #define ec_dbg_evt(fmt, ...) \
179 	ec_dbg(EC_DBG_EVT, fmt, ##__VA_ARGS__)
180 #define ec_dbg_ref(ec, fmt, ...) \
181 	ec_dbg_raw("%lu: " fmt, ec->reference_count, ## __VA_ARGS__)
182 
183 /* --------------------------------------------------------------------------
184  *                           Device Flags
185  * -------------------------------------------------------------------------- */
186 
187 static bool acpi_ec_started(struct acpi_ec *ec)
188 {
189 	return test_bit(EC_FLAGS_STARTED, &ec->flags) &&
190 	       !test_bit(EC_FLAGS_STOPPED, &ec->flags);
191 }
192 
193 static bool acpi_ec_flushed(struct acpi_ec *ec)
194 {
195 	return ec->reference_count == 1;
196 }
197 
198 /* --------------------------------------------------------------------------
199  *                           EC Registers
200  * -------------------------------------------------------------------------- */
201 
202 static inline u8 acpi_ec_read_status(struct acpi_ec *ec)
203 {
204 	u8 x = inb(ec->command_addr);
205 
206 	ec_dbg_raw("EC_SC(R) = 0x%2.2x "
207 		   "SCI_EVT=%d BURST=%d CMD=%d IBF=%d OBF=%d",
208 		   x,
209 		   !!(x & ACPI_EC_FLAG_SCI),
210 		   !!(x & ACPI_EC_FLAG_BURST),
211 		   !!(x & ACPI_EC_FLAG_CMD),
212 		   !!(x & ACPI_EC_FLAG_IBF),
213 		   !!(x & ACPI_EC_FLAG_OBF));
214 	return x;
215 }
216 
217 static inline u8 acpi_ec_read_data(struct acpi_ec *ec)
218 {
219 	u8 x = inb(ec->data_addr);
220 
221 	ec->curr->timestamp = jiffies;
222 	ec_dbg_raw("EC_DATA(R) = 0x%2.2x", x);
223 	return x;
224 }
225 
226 static inline void acpi_ec_write_cmd(struct acpi_ec *ec, u8 command)
227 {
228 	ec_dbg_raw("EC_SC(W) = 0x%2.2x", command);
229 	outb(command, ec->command_addr);
230 	ec->curr->timestamp = jiffies;
231 }
232 
233 static inline void acpi_ec_write_data(struct acpi_ec *ec, u8 data)
234 {
235 	ec_dbg_raw("EC_DATA(W) = 0x%2.2x", data);
236 	outb(data, ec->data_addr);
237 	ec->curr->timestamp = jiffies;
238 }
239 
240 #ifdef DEBUG
241 static const char *acpi_ec_cmd_string(u8 cmd)
242 {
243 	switch (cmd) {
244 	case 0x80:
245 		return "RD_EC";
246 	case 0x81:
247 		return "WR_EC";
248 	case 0x82:
249 		return "BE_EC";
250 	case 0x83:
251 		return "BD_EC";
252 	case 0x84:
253 		return "QR_EC";
254 	}
255 	return "UNKNOWN";
256 }
257 #else
258 #define acpi_ec_cmd_string(cmd)		"UNDEF"
259 #endif
260 
261 /* --------------------------------------------------------------------------
262  *                           GPE Registers
263  * -------------------------------------------------------------------------- */
264 
265 static inline bool acpi_ec_is_gpe_raised(struct acpi_ec *ec)
266 {
267 	acpi_event_status gpe_status = 0;
268 
269 	(void)acpi_get_gpe_status(NULL, ec->gpe, &gpe_status);
270 	return (gpe_status & ACPI_EVENT_FLAG_SET) ? true : false;
271 }
272 
273 static inline void acpi_ec_enable_gpe(struct acpi_ec *ec, bool open)
274 {
275 	if (open)
276 		acpi_enable_gpe(NULL, ec->gpe);
277 	else {
278 		BUG_ON(ec->reference_count < 1);
279 		acpi_set_gpe(NULL, ec->gpe, ACPI_GPE_ENABLE);
280 	}
281 	if (acpi_ec_is_gpe_raised(ec)) {
282 		/*
283 		 * On some platforms, EN=1 writes cannot trigger GPE. So
284 		 * software need to manually trigger a pseudo GPE event on
285 		 * EN=1 writes.
286 		 */
287 		ec_dbg_raw("Polling quirk");
288 		advance_transaction(ec);
289 	}
290 }
291 
292 static inline void acpi_ec_disable_gpe(struct acpi_ec *ec, bool close)
293 {
294 	if (close)
295 		acpi_disable_gpe(NULL, ec->gpe);
296 	else {
297 		BUG_ON(ec->reference_count < 1);
298 		acpi_set_gpe(NULL, ec->gpe, ACPI_GPE_DISABLE);
299 	}
300 }
301 
302 static inline void acpi_ec_clear_gpe(struct acpi_ec *ec)
303 {
304 	/*
305 	 * GPE STS is a W1C register, which means:
306 	 * 1. Software can clear it without worrying about clearing other
307 	 *    GPEs' STS bits when the hardware sets them in parallel.
308 	 * 2. As long as software can ensure only clearing it when it is
309 	 *    set, hardware won't set it in parallel.
310 	 * So software can clear GPE in any contexts.
311 	 * Warning: do not move the check into advance_transaction() as the
312 	 * EC commands will be sent without GPE raised.
313 	 */
314 	if (!acpi_ec_is_gpe_raised(ec))
315 		return;
316 	acpi_clear_gpe(NULL, ec->gpe);
317 }
318 
319 /* --------------------------------------------------------------------------
320  *                           Transaction Management
321  * -------------------------------------------------------------------------- */
322 
323 static void acpi_ec_submit_request(struct acpi_ec *ec)
324 {
325 	ec->reference_count++;
326 	if (ec->reference_count == 1)
327 		acpi_ec_enable_gpe(ec, true);
328 }
329 
330 static void acpi_ec_complete_request(struct acpi_ec *ec)
331 {
332 	bool flushed = false;
333 
334 	ec->reference_count--;
335 	if (ec->reference_count == 0)
336 		acpi_ec_disable_gpe(ec, true);
337 	flushed = acpi_ec_flushed(ec);
338 	if (flushed)
339 		wake_up(&ec->wait);
340 }
341 
342 static void acpi_ec_set_storm(struct acpi_ec *ec, u8 flag)
343 {
344 	if (!test_bit(flag, &ec->flags)) {
345 		acpi_ec_disable_gpe(ec, false);
346 		ec_dbg_drv("Polling enabled");
347 		set_bit(flag, &ec->flags);
348 	}
349 }
350 
351 static void acpi_ec_clear_storm(struct acpi_ec *ec, u8 flag)
352 {
353 	if (test_bit(flag, &ec->flags)) {
354 		clear_bit(flag, &ec->flags);
355 		acpi_ec_enable_gpe(ec, false);
356 		ec_dbg_drv("Polling disabled");
357 	}
358 }
359 
360 /*
361  * acpi_ec_submit_flushable_request() - Increase the reference count unless
362  *                                      the flush operation is not in
363  *                                      progress
364  * @ec: the EC device
365  *
366  * This function must be used before taking a new action that should hold
367  * the reference count.  If this function returns false, then the action
368  * must be discarded or it will prevent the flush operation from being
369  * completed.
370  */
371 static bool acpi_ec_submit_flushable_request(struct acpi_ec *ec)
372 {
373 	if (!acpi_ec_started(ec))
374 		return false;
375 	acpi_ec_submit_request(ec);
376 	return true;
377 }
378 
379 static void acpi_ec_submit_query(struct acpi_ec *ec)
380 {
381 	if (!test_and_set_bit(EC_FLAGS_QUERY_PENDING, &ec->flags)) {
382 		ec_dbg_req("Event started");
383 		schedule_work(&ec->work);
384 	}
385 }
386 
387 static void acpi_ec_complete_query(struct acpi_ec *ec)
388 {
389 	if (ec->curr->command == ACPI_EC_COMMAND_QUERY) {
390 		clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
391 		ec_dbg_req("Event stopped");
392 	}
393 }
394 
395 static int ec_transaction_completed(struct acpi_ec *ec)
396 {
397 	unsigned long flags;
398 	int ret = 0;
399 
400 	spin_lock_irqsave(&ec->lock, flags);
401 	if (ec->curr && (ec->curr->flags & ACPI_EC_COMMAND_COMPLETE))
402 		ret = 1;
403 	spin_unlock_irqrestore(&ec->lock, flags);
404 	return ret;
405 }
406 
407 static void advance_transaction(struct acpi_ec *ec)
408 {
409 	struct transaction *t;
410 	u8 status;
411 	bool wakeup = false;
412 
413 	ec_dbg_stm("%s (%d)", in_interrupt() ? "IRQ" : "TASK",
414 		   smp_processor_id());
415 	/*
416 	 * By always clearing STS before handling all indications, we can
417 	 * ensure a hardware STS 0->1 change after this clearing can always
418 	 * trigger a GPE interrupt.
419 	 */
420 	acpi_ec_clear_gpe(ec);
421 	status = acpi_ec_read_status(ec);
422 	t = ec->curr;
423 	if (!t)
424 		goto err;
425 	if (t->flags & ACPI_EC_COMMAND_POLL) {
426 		if (t->wlen > t->wi) {
427 			if ((status & ACPI_EC_FLAG_IBF) == 0)
428 				acpi_ec_write_data(ec, t->wdata[t->wi++]);
429 			else
430 				goto err;
431 		} else if (t->rlen > t->ri) {
432 			if ((status & ACPI_EC_FLAG_OBF) == 1) {
433 				t->rdata[t->ri++] = acpi_ec_read_data(ec);
434 				if (t->rlen == t->ri) {
435 					t->flags |= ACPI_EC_COMMAND_COMPLETE;
436 					if (t->command == ACPI_EC_COMMAND_QUERY)
437 						ec_dbg_req("Command(%s) hardware completion",
438 							   acpi_ec_cmd_string(t->command));
439 					wakeup = true;
440 				}
441 			} else
442 				goto err;
443 		} else if (t->wlen == t->wi &&
444 			   (status & ACPI_EC_FLAG_IBF) == 0) {
445 			t->flags |= ACPI_EC_COMMAND_COMPLETE;
446 			wakeup = true;
447 		}
448 		goto out;
449 	} else {
450 		if (EC_FLAGS_QUERY_HANDSHAKE &&
451 		    !(status & ACPI_EC_FLAG_SCI) &&
452 		    (t->command == ACPI_EC_COMMAND_QUERY)) {
453 			t->flags |= ACPI_EC_COMMAND_POLL;
454 			acpi_ec_complete_query(ec);
455 			t->rdata[t->ri++] = 0x00;
456 			t->flags |= ACPI_EC_COMMAND_COMPLETE;
457 			ec_dbg_req("Command(%s) software completion",
458 				   acpi_ec_cmd_string(t->command));
459 			wakeup = true;
460 		} else if ((status & ACPI_EC_FLAG_IBF) == 0) {
461 			acpi_ec_write_cmd(ec, t->command);
462 			t->flags |= ACPI_EC_COMMAND_POLL;
463 			acpi_ec_complete_query(ec);
464 		} else
465 			goto err;
466 		goto out;
467 	}
468 err:
469 	/*
470 	 * If SCI bit is set, then don't think it's a false IRQ
471 	 * otherwise will take a not handled IRQ as a false one.
472 	 */
473 	if (!(status & ACPI_EC_FLAG_SCI)) {
474 		if (in_interrupt() && t) {
475 			if (t->irq_count < ec_storm_threshold)
476 				++t->irq_count;
477 			/* Allow triggering on 0 threshold */
478 			if (t->irq_count == ec_storm_threshold)
479 				acpi_ec_set_storm(ec, EC_FLAGS_COMMAND_STORM);
480 		}
481 	}
482 out:
483 	if (status & ACPI_EC_FLAG_SCI)
484 		acpi_ec_submit_query(ec);
485 	if (wakeup && in_interrupt())
486 		wake_up(&ec->wait);
487 }
488 
489 static void start_transaction(struct acpi_ec *ec)
490 {
491 	ec->curr->irq_count = ec->curr->wi = ec->curr->ri = 0;
492 	ec->curr->flags = 0;
493 	ec->curr->timestamp = jiffies;
494 	advance_transaction(ec);
495 }
496 
497 static int ec_poll(struct acpi_ec *ec)
498 {
499 	unsigned long flags;
500 	int repeat = 5; /* number of command restarts */
501 
502 	while (repeat--) {
503 		unsigned long delay = jiffies +
504 			msecs_to_jiffies(ec_delay);
505 		unsigned long usecs = ACPI_EC_UDELAY_POLL;
506 		do {
507 			/* don't sleep with disabled interrupts */
508 			if (EC_FLAGS_MSI || irqs_disabled()) {
509 				usecs = ACPI_EC_MSI_UDELAY;
510 				udelay(usecs);
511 				if (ec_transaction_completed(ec))
512 					return 0;
513 			} else {
514 				if (wait_event_timeout(ec->wait,
515 						ec_transaction_completed(ec),
516 						usecs_to_jiffies(usecs)))
517 					return 0;
518 			}
519 			spin_lock_irqsave(&ec->lock, flags);
520 			if (time_after(jiffies,
521 					ec->curr->timestamp +
522 					usecs_to_jiffies(usecs)))
523 				advance_transaction(ec);
524 			spin_unlock_irqrestore(&ec->lock, flags);
525 		} while (time_before(jiffies, delay));
526 		pr_debug("controller reset, restart transaction\n");
527 		spin_lock_irqsave(&ec->lock, flags);
528 		start_transaction(ec);
529 		spin_unlock_irqrestore(&ec->lock, flags);
530 	}
531 	return -ETIME;
532 }
533 
534 static int acpi_ec_transaction_unlocked(struct acpi_ec *ec,
535 					struct transaction *t)
536 {
537 	unsigned long tmp;
538 	int ret = 0;
539 
540 	if (EC_FLAGS_MSI)
541 		udelay(ACPI_EC_MSI_UDELAY);
542 	/* start transaction */
543 	spin_lock_irqsave(&ec->lock, tmp);
544 	/* Enable GPE for command processing (IBF=0/OBF=1) */
545 	if (!acpi_ec_submit_flushable_request(ec)) {
546 		ret = -EINVAL;
547 		goto unlock;
548 	}
549 	ec_dbg_ref(ec, "Increase command");
550 	/* following two actions should be kept atomic */
551 	ec->curr = t;
552 	ec_dbg_req("Command(%s) started", acpi_ec_cmd_string(t->command));
553 	start_transaction(ec);
554 	spin_unlock_irqrestore(&ec->lock, tmp);
555 	ret = ec_poll(ec);
556 	spin_lock_irqsave(&ec->lock, tmp);
557 	if (t->irq_count == ec_storm_threshold)
558 		acpi_ec_clear_storm(ec, EC_FLAGS_COMMAND_STORM);
559 	ec_dbg_req("Command(%s) stopped", acpi_ec_cmd_string(t->command));
560 	ec->curr = NULL;
561 	/* Disable GPE for command processing (IBF=0/OBF=1) */
562 	acpi_ec_complete_request(ec);
563 	ec_dbg_ref(ec, "Decrease command");
564 unlock:
565 	spin_unlock_irqrestore(&ec->lock, tmp);
566 	return ret;
567 }
568 
569 static int acpi_ec_transaction(struct acpi_ec *ec, struct transaction *t)
570 {
571 	int status;
572 	u32 glk;
573 
574 	if (!ec || (!t) || (t->wlen && !t->wdata) || (t->rlen && !t->rdata))
575 		return -EINVAL;
576 	if (t->rdata)
577 		memset(t->rdata, 0, t->rlen);
578 	mutex_lock(&ec->mutex);
579 	if (ec->global_lock) {
580 		status = acpi_acquire_global_lock(ACPI_EC_UDELAY_GLK, &glk);
581 		if (ACPI_FAILURE(status)) {
582 			status = -ENODEV;
583 			goto unlock;
584 		}
585 	}
586 
587 	status = acpi_ec_transaction_unlocked(ec, t);
588 
589 	if (test_bit(EC_FLAGS_COMMAND_STORM, &ec->flags))
590 		msleep(1);
591 	if (ec->global_lock)
592 		acpi_release_global_lock(glk);
593 unlock:
594 	mutex_unlock(&ec->mutex);
595 	return status;
596 }
597 
598 static int acpi_ec_burst_enable(struct acpi_ec *ec)
599 {
600 	u8 d;
601 	struct transaction t = {.command = ACPI_EC_BURST_ENABLE,
602 				.wdata = NULL, .rdata = &d,
603 				.wlen = 0, .rlen = 1};
604 
605 	return acpi_ec_transaction(ec, &t);
606 }
607 
608 static int acpi_ec_burst_disable(struct acpi_ec *ec)
609 {
610 	struct transaction t = {.command = ACPI_EC_BURST_DISABLE,
611 				.wdata = NULL, .rdata = NULL,
612 				.wlen = 0, .rlen = 0};
613 
614 	return (acpi_ec_read_status(ec) & ACPI_EC_FLAG_BURST) ?
615 				acpi_ec_transaction(ec, &t) : 0;
616 }
617 
618 static int acpi_ec_read(struct acpi_ec *ec, u8 address, u8 *data)
619 {
620 	int result;
621 	u8 d;
622 	struct transaction t = {.command = ACPI_EC_COMMAND_READ,
623 				.wdata = &address, .rdata = &d,
624 				.wlen = 1, .rlen = 1};
625 
626 	result = acpi_ec_transaction(ec, &t);
627 	*data = d;
628 	return result;
629 }
630 
631 static int acpi_ec_write(struct acpi_ec *ec, u8 address, u8 data)
632 {
633 	u8 wdata[2] = { address, data };
634 	struct transaction t = {.command = ACPI_EC_COMMAND_WRITE,
635 				.wdata = wdata, .rdata = NULL,
636 				.wlen = 2, .rlen = 0};
637 
638 	return acpi_ec_transaction(ec, &t);
639 }
640 
641 int ec_read(u8 addr, u8 *val)
642 {
643 	int err;
644 	u8 temp_data;
645 
646 	if (!first_ec)
647 		return -ENODEV;
648 
649 	err = acpi_ec_read(first_ec, addr, &temp_data);
650 
651 	if (!err) {
652 		*val = temp_data;
653 		return 0;
654 	}
655 	return err;
656 }
657 EXPORT_SYMBOL(ec_read);
658 
659 int ec_write(u8 addr, u8 val)
660 {
661 	int err;
662 
663 	if (!first_ec)
664 		return -ENODEV;
665 
666 	err = acpi_ec_write(first_ec, addr, val);
667 
668 	return err;
669 }
670 EXPORT_SYMBOL(ec_write);
671 
672 int ec_transaction(u8 command,
673 		   const u8 *wdata, unsigned wdata_len,
674 		   u8 *rdata, unsigned rdata_len)
675 {
676 	struct transaction t = {.command = command,
677 				.wdata = wdata, .rdata = rdata,
678 				.wlen = wdata_len, .rlen = rdata_len};
679 
680 	if (!first_ec)
681 		return -ENODEV;
682 
683 	return acpi_ec_transaction(first_ec, &t);
684 }
685 EXPORT_SYMBOL(ec_transaction);
686 
687 /* Get the handle to the EC device */
688 acpi_handle ec_get_handle(void)
689 {
690 	if (!first_ec)
691 		return NULL;
692 	return first_ec->handle;
693 }
694 EXPORT_SYMBOL(ec_get_handle);
695 
696 /*
697  * Process _Q events that might have accumulated in the EC.
698  * Run with locked ec mutex.
699  */
700 static void acpi_ec_clear(struct acpi_ec *ec)
701 {
702 	int i, status;
703 	u8 value = 0;
704 
705 	for (i = 0; i < ACPI_EC_CLEAR_MAX; i++) {
706 		status = acpi_ec_query(ec, &value);
707 		if (status || !value)
708 			break;
709 	}
710 
711 	if (unlikely(i == ACPI_EC_CLEAR_MAX))
712 		pr_warn("Warning: Maximum of %d stale EC events cleared\n", i);
713 	else
714 		pr_info("%d stale EC events cleared\n", i);
715 }
716 
717 static void acpi_ec_start(struct acpi_ec *ec, bool resuming)
718 {
719 	unsigned long flags;
720 
721 	spin_lock_irqsave(&ec->lock, flags);
722 	if (!test_and_set_bit(EC_FLAGS_STARTED, &ec->flags)) {
723 		ec_dbg_drv("Starting EC");
724 		/* Enable GPE for event processing (SCI_EVT=1) */
725 		if (!resuming) {
726 			acpi_ec_submit_request(ec);
727 			ec_dbg_ref(ec, "Increase driver");
728 		}
729 		ec_log_drv("EC started");
730 	}
731 	spin_unlock_irqrestore(&ec->lock, flags);
732 }
733 
734 static bool acpi_ec_stopped(struct acpi_ec *ec)
735 {
736 	unsigned long flags;
737 	bool flushed;
738 
739 	spin_lock_irqsave(&ec->lock, flags);
740 	flushed = acpi_ec_flushed(ec);
741 	spin_unlock_irqrestore(&ec->lock, flags);
742 	return flushed;
743 }
744 
745 static void acpi_ec_stop(struct acpi_ec *ec, bool suspending)
746 {
747 	unsigned long flags;
748 
749 	spin_lock_irqsave(&ec->lock, flags);
750 	if (acpi_ec_started(ec)) {
751 		ec_dbg_drv("Stopping EC");
752 		set_bit(EC_FLAGS_STOPPED, &ec->flags);
753 		spin_unlock_irqrestore(&ec->lock, flags);
754 		wait_event(ec->wait, acpi_ec_stopped(ec));
755 		spin_lock_irqsave(&ec->lock, flags);
756 		/* Disable GPE for event processing (SCI_EVT=1) */
757 		if (!suspending) {
758 			acpi_ec_complete_request(ec);
759 			ec_dbg_ref(ec, "Decrease driver");
760 		}
761 		clear_bit(EC_FLAGS_STARTED, &ec->flags);
762 		clear_bit(EC_FLAGS_STOPPED, &ec->flags);
763 		ec_log_drv("EC stopped");
764 	}
765 	spin_unlock_irqrestore(&ec->lock, flags);
766 }
767 
768 void acpi_ec_block_transactions(void)
769 {
770 	struct acpi_ec *ec = first_ec;
771 
772 	if (!ec)
773 		return;
774 
775 	mutex_lock(&ec->mutex);
776 	/* Prevent transactions from being carried out */
777 	acpi_ec_stop(ec, true);
778 	mutex_unlock(&ec->mutex);
779 }
780 
781 void acpi_ec_unblock_transactions(void)
782 {
783 	struct acpi_ec *ec = first_ec;
784 
785 	if (!ec)
786 		return;
787 
788 	/* Allow transactions to be carried out again */
789 	acpi_ec_start(ec, true);
790 
791 	if (EC_FLAGS_CLEAR_ON_RESUME)
792 		acpi_ec_clear(ec);
793 }
794 
795 void acpi_ec_unblock_transactions_early(void)
796 {
797 	/*
798 	 * Allow transactions to happen again (this function is called from
799 	 * atomic context during wakeup, so we don't need to acquire the mutex).
800 	 */
801 	if (first_ec)
802 		acpi_ec_start(first_ec, true);
803 }
804 
805 /* --------------------------------------------------------------------------
806                                 Event Management
807    -------------------------------------------------------------------------- */
808 static struct acpi_ec_query_handler *
809 acpi_ec_get_query_handler(struct acpi_ec_query_handler *handler)
810 {
811 	if (handler)
812 		kref_get(&handler->kref);
813 	return handler;
814 }
815 
816 static void acpi_ec_query_handler_release(struct kref *kref)
817 {
818 	struct acpi_ec_query_handler *handler =
819 		container_of(kref, struct acpi_ec_query_handler, kref);
820 
821 	kfree(handler);
822 }
823 
824 static void acpi_ec_put_query_handler(struct acpi_ec_query_handler *handler)
825 {
826 	kref_put(&handler->kref, acpi_ec_query_handler_release);
827 }
828 
829 int acpi_ec_add_query_handler(struct acpi_ec *ec, u8 query_bit,
830 			      acpi_handle handle, acpi_ec_query_func func,
831 			      void *data)
832 {
833 	struct acpi_ec_query_handler *handler =
834 	    kzalloc(sizeof(struct acpi_ec_query_handler), GFP_KERNEL);
835 
836 	if (!handler)
837 		return -ENOMEM;
838 
839 	handler->query_bit = query_bit;
840 	handler->handle = handle;
841 	handler->func = func;
842 	handler->data = data;
843 	mutex_lock(&ec->mutex);
844 	kref_init(&handler->kref);
845 	list_add(&handler->node, &ec->list);
846 	mutex_unlock(&ec->mutex);
847 	return 0;
848 }
849 EXPORT_SYMBOL_GPL(acpi_ec_add_query_handler);
850 
851 void acpi_ec_remove_query_handler(struct acpi_ec *ec, u8 query_bit)
852 {
853 	struct acpi_ec_query_handler *handler, *tmp;
854 	LIST_HEAD(free_list);
855 
856 	mutex_lock(&ec->mutex);
857 	list_for_each_entry_safe(handler, tmp, &ec->list, node) {
858 		if (query_bit == handler->query_bit) {
859 			list_del_init(&handler->node);
860 			list_add(&handler->node, &free_list);
861 		}
862 	}
863 	mutex_unlock(&ec->mutex);
864 	list_for_each_entry_safe(handler, tmp, &free_list, node)
865 		acpi_ec_put_query_handler(handler);
866 }
867 EXPORT_SYMBOL_GPL(acpi_ec_remove_query_handler);
868 
869 static void acpi_ec_run(void *cxt)
870 {
871 	struct acpi_ec_query_handler *handler = cxt;
872 
873 	if (!handler)
874 		return;
875 	ec_dbg_evt("Query(0x%02x) started", handler->query_bit);
876 	if (handler->func)
877 		handler->func(handler->data);
878 	else if (handler->handle)
879 		acpi_evaluate_object(handler->handle, NULL, NULL, NULL);
880 	ec_dbg_evt("Query(0x%02x) stopped", handler->query_bit);
881 	acpi_ec_put_query_handler(handler);
882 }
883 
884 static int acpi_ec_query(struct acpi_ec *ec, u8 *data)
885 {
886 	u8 value = 0;
887 	int result;
888 	acpi_status status;
889 	struct acpi_ec_query_handler *handler;
890 	struct transaction t = {.command = ACPI_EC_COMMAND_QUERY,
891 				.wdata = NULL, .rdata = &value,
892 				.wlen = 0, .rlen = 1};
893 
894 	/*
895 	 * Query the EC to find out which _Qxx method we need to evaluate.
896 	 * Note that successful completion of the query causes the ACPI_EC_SCI
897 	 * bit to be cleared (and thus clearing the interrupt source).
898 	 */
899 	result = acpi_ec_transaction(ec, &t);
900 	if (result)
901 		return result;
902 	if (data)
903 		*data = value;
904 	if (!value)
905 		return -ENODATA;
906 
907 	mutex_lock(&ec->mutex);
908 	list_for_each_entry(handler, &ec->list, node) {
909 		if (value == handler->query_bit) {
910 			/* have custom handler for this bit */
911 			handler = acpi_ec_get_query_handler(handler);
912 			ec_dbg_evt("Query(0x%02x) scheduled",
913 				   handler->query_bit);
914 			status = acpi_os_execute((handler->func) ?
915 				OSL_NOTIFY_HANDLER : OSL_GPE_HANDLER,
916 				acpi_ec_run, handler);
917 			if (ACPI_FAILURE(status))
918 				result = -EBUSY;
919 			break;
920 		}
921 	}
922 	mutex_unlock(&ec->mutex);
923 	return result;
924 }
925 
926 static void acpi_ec_gpe_poller(struct work_struct *work)
927 {
928 	struct acpi_ec *ec = container_of(work, struct acpi_ec, work);
929 
930 	acpi_ec_query(ec, NULL);
931 }
932 
933 static u32 acpi_ec_gpe_handler(acpi_handle gpe_device,
934 	u32 gpe_number, void *data)
935 {
936 	unsigned long flags;
937 	struct acpi_ec *ec = data;
938 
939 	spin_lock_irqsave(&ec->lock, flags);
940 	advance_transaction(ec);
941 	spin_unlock_irqrestore(&ec->lock, flags);
942 	return ACPI_INTERRUPT_HANDLED;
943 }
944 
945 /* --------------------------------------------------------------------------
946  *                           Address Space Management
947  * -------------------------------------------------------------------------- */
948 
949 static acpi_status
950 acpi_ec_space_handler(u32 function, acpi_physical_address address,
951 		      u32 bits, u64 *value64,
952 		      void *handler_context, void *region_context)
953 {
954 	struct acpi_ec *ec = handler_context;
955 	int result = 0, i, bytes = bits / 8;
956 	u8 *value = (u8 *)value64;
957 
958 	if ((address > 0xFF) || !value || !handler_context)
959 		return AE_BAD_PARAMETER;
960 
961 	if (function != ACPI_READ && function != ACPI_WRITE)
962 		return AE_BAD_PARAMETER;
963 
964 	if (EC_FLAGS_MSI || bits > 8)
965 		acpi_ec_burst_enable(ec);
966 
967 	for (i = 0; i < bytes; ++i, ++address, ++value)
968 		result = (function == ACPI_READ) ?
969 			acpi_ec_read(ec, address, value) :
970 			acpi_ec_write(ec, address, *value);
971 
972 	if (EC_FLAGS_MSI || bits > 8)
973 		acpi_ec_burst_disable(ec);
974 
975 	switch (result) {
976 	case -EINVAL:
977 		return AE_BAD_PARAMETER;
978 	case -ENODEV:
979 		return AE_NOT_FOUND;
980 	case -ETIME:
981 		return AE_TIME;
982 	default:
983 		return AE_OK;
984 	}
985 }
986 
987 /* --------------------------------------------------------------------------
988  *                             Driver Interface
989  * -------------------------------------------------------------------------- */
990 
991 static acpi_status
992 ec_parse_io_ports(struct acpi_resource *resource, void *context);
993 
994 static struct acpi_ec *make_acpi_ec(void)
995 {
996 	struct acpi_ec *ec = kzalloc(sizeof(struct acpi_ec), GFP_KERNEL);
997 
998 	if (!ec)
999 		return NULL;
1000 	ec->flags = 1 << EC_FLAGS_QUERY_PENDING;
1001 	mutex_init(&ec->mutex);
1002 	init_waitqueue_head(&ec->wait);
1003 	INIT_LIST_HEAD(&ec->list);
1004 	spin_lock_init(&ec->lock);
1005 	INIT_WORK(&ec->work, acpi_ec_gpe_poller);
1006 	return ec;
1007 }
1008 
1009 static acpi_status
1010 acpi_ec_register_query_methods(acpi_handle handle, u32 level,
1011 			       void *context, void **return_value)
1012 {
1013 	char node_name[5];
1014 	struct acpi_buffer buffer = { sizeof(node_name), node_name };
1015 	struct acpi_ec *ec = context;
1016 	int value = 0;
1017 	acpi_status status;
1018 
1019 	status = acpi_get_name(handle, ACPI_SINGLE_NAME, &buffer);
1020 
1021 	if (ACPI_SUCCESS(status) && sscanf(node_name, "_Q%x", &value) == 1)
1022 		acpi_ec_add_query_handler(ec, value, handle, NULL, NULL);
1023 	return AE_OK;
1024 }
1025 
1026 static acpi_status
1027 ec_parse_device(acpi_handle handle, u32 Level, void *context, void **retval)
1028 {
1029 	acpi_status status;
1030 	unsigned long long tmp = 0;
1031 	struct acpi_ec *ec = context;
1032 
1033 	/* clear addr values, ec_parse_io_ports depend on it */
1034 	ec->command_addr = ec->data_addr = 0;
1035 
1036 	status = acpi_walk_resources(handle, METHOD_NAME__CRS,
1037 				     ec_parse_io_ports, ec);
1038 	if (ACPI_FAILURE(status))
1039 		return status;
1040 
1041 	/* Get GPE bit assignment (EC events). */
1042 	/* TODO: Add support for _GPE returning a package */
1043 	status = acpi_evaluate_integer(handle, "_GPE", NULL, &tmp);
1044 	if (ACPI_FAILURE(status))
1045 		return status;
1046 	ec->gpe = tmp;
1047 	/* Use the global lock for all EC transactions? */
1048 	tmp = 0;
1049 	acpi_evaluate_integer(handle, "_GLK", NULL, &tmp);
1050 	ec->global_lock = tmp;
1051 	ec->handle = handle;
1052 	return AE_CTRL_TERMINATE;
1053 }
1054 
1055 static int ec_install_handlers(struct acpi_ec *ec)
1056 {
1057 	acpi_status status;
1058 
1059 	if (test_bit(EC_FLAGS_HANDLERS_INSTALLED, &ec->flags))
1060 		return 0;
1061 	status = acpi_install_gpe_raw_handler(NULL, ec->gpe,
1062 				  ACPI_GPE_EDGE_TRIGGERED,
1063 				  &acpi_ec_gpe_handler, ec);
1064 	if (ACPI_FAILURE(status))
1065 		return -ENODEV;
1066 
1067 	acpi_ec_start(ec, false);
1068 	status = acpi_install_address_space_handler(ec->handle,
1069 						    ACPI_ADR_SPACE_EC,
1070 						    &acpi_ec_space_handler,
1071 						    NULL, ec);
1072 	if (ACPI_FAILURE(status)) {
1073 		if (status == AE_NOT_FOUND) {
1074 			/*
1075 			 * Maybe OS fails in evaluating the _REG object.
1076 			 * The AE_NOT_FOUND error will be ignored and OS
1077 			 * continue to initialize EC.
1078 			 */
1079 			pr_err("Fail in evaluating the _REG object"
1080 				" of EC device. Broken bios is suspected.\n");
1081 		} else {
1082 			acpi_ec_stop(ec, false);
1083 			acpi_remove_gpe_handler(NULL, ec->gpe,
1084 				&acpi_ec_gpe_handler);
1085 			return -ENODEV;
1086 		}
1087 	}
1088 
1089 	set_bit(EC_FLAGS_HANDLERS_INSTALLED, &ec->flags);
1090 	return 0;
1091 }
1092 
1093 static void ec_remove_handlers(struct acpi_ec *ec)
1094 {
1095 	if (!test_bit(EC_FLAGS_HANDLERS_INSTALLED, &ec->flags))
1096 		return;
1097 	acpi_ec_stop(ec, false);
1098 	if (ACPI_FAILURE(acpi_remove_address_space_handler(ec->handle,
1099 				ACPI_ADR_SPACE_EC, &acpi_ec_space_handler)))
1100 		pr_err("failed to remove space handler\n");
1101 	if (ACPI_FAILURE(acpi_remove_gpe_handler(NULL, ec->gpe,
1102 				&acpi_ec_gpe_handler)))
1103 		pr_err("failed to remove gpe handler\n");
1104 	clear_bit(EC_FLAGS_HANDLERS_INSTALLED, &ec->flags);
1105 }
1106 
1107 static int acpi_ec_add(struct acpi_device *device)
1108 {
1109 	struct acpi_ec *ec = NULL;
1110 	int ret;
1111 
1112 	strcpy(acpi_device_name(device), ACPI_EC_DEVICE_NAME);
1113 	strcpy(acpi_device_class(device), ACPI_EC_CLASS);
1114 
1115 	/* Check for boot EC */
1116 	if (boot_ec &&
1117 	    (boot_ec->handle == device->handle ||
1118 	     boot_ec->handle == ACPI_ROOT_OBJECT)) {
1119 		ec = boot_ec;
1120 		boot_ec = NULL;
1121 	} else {
1122 		ec = make_acpi_ec();
1123 		if (!ec)
1124 			return -ENOMEM;
1125 	}
1126 	if (ec_parse_device(device->handle, 0, ec, NULL) !=
1127 		AE_CTRL_TERMINATE) {
1128 			kfree(ec);
1129 			return -EINVAL;
1130 	}
1131 
1132 	/* Find and register all query methods */
1133 	acpi_walk_namespace(ACPI_TYPE_METHOD, ec->handle, 1,
1134 			    acpi_ec_register_query_methods, NULL, ec, NULL);
1135 
1136 	if (!first_ec)
1137 		first_ec = ec;
1138 	device->driver_data = ec;
1139 
1140 	ret = !!request_region(ec->data_addr, 1, "EC data");
1141 	WARN(!ret, "Could not request EC data io port 0x%lx", ec->data_addr);
1142 	ret = !!request_region(ec->command_addr, 1, "EC cmd");
1143 	WARN(!ret, "Could not request EC cmd io port 0x%lx", ec->command_addr);
1144 
1145 	pr_info("GPE = 0x%lx, I/O: command/status = 0x%lx, data = 0x%lx\n",
1146 			  ec->gpe, ec->command_addr, ec->data_addr);
1147 
1148 	ret = ec_install_handlers(ec);
1149 
1150 	/* Reprobe devices depending on the EC */
1151 	acpi_walk_dep_device_list(ec->handle);
1152 
1153 	/* EC is fully operational, allow queries */
1154 	clear_bit(EC_FLAGS_QUERY_PENDING, &ec->flags);
1155 
1156 	/* Clear stale _Q events if hardware might require that */
1157 	if (EC_FLAGS_CLEAR_ON_RESUME)
1158 		acpi_ec_clear(ec);
1159 	return ret;
1160 }
1161 
1162 static int acpi_ec_remove(struct acpi_device *device)
1163 {
1164 	struct acpi_ec *ec;
1165 	struct acpi_ec_query_handler *handler, *tmp;
1166 
1167 	if (!device)
1168 		return -EINVAL;
1169 
1170 	ec = acpi_driver_data(device);
1171 	ec_remove_handlers(ec);
1172 	mutex_lock(&ec->mutex);
1173 	list_for_each_entry_safe(handler, tmp, &ec->list, node) {
1174 		list_del(&handler->node);
1175 		kfree(handler);
1176 	}
1177 	mutex_unlock(&ec->mutex);
1178 	release_region(ec->data_addr, 1);
1179 	release_region(ec->command_addr, 1);
1180 	device->driver_data = NULL;
1181 	if (ec == first_ec)
1182 		first_ec = NULL;
1183 	kfree(ec);
1184 	return 0;
1185 }
1186 
1187 static acpi_status
1188 ec_parse_io_ports(struct acpi_resource *resource, void *context)
1189 {
1190 	struct acpi_ec *ec = context;
1191 
1192 	if (resource->type != ACPI_RESOURCE_TYPE_IO)
1193 		return AE_OK;
1194 
1195 	/*
1196 	 * The first address region returned is the data port, and
1197 	 * the second address region returned is the status/command
1198 	 * port.
1199 	 */
1200 	if (ec->data_addr == 0)
1201 		ec->data_addr = resource->data.io.minimum;
1202 	else if (ec->command_addr == 0)
1203 		ec->command_addr = resource->data.io.minimum;
1204 	else
1205 		return AE_CTRL_TERMINATE;
1206 
1207 	return AE_OK;
1208 }
1209 
1210 int __init acpi_boot_ec_enable(void)
1211 {
1212 	if (!boot_ec || test_bit(EC_FLAGS_HANDLERS_INSTALLED, &boot_ec->flags))
1213 		return 0;
1214 	if (!ec_install_handlers(boot_ec)) {
1215 		first_ec = boot_ec;
1216 		return 0;
1217 	}
1218 	return -EFAULT;
1219 }
1220 
1221 static const struct acpi_device_id ec_device_ids[] = {
1222 	{"PNP0C09", 0},
1223 	{"", 0},
1224 };
1225 
1226 /* Some BIOS do not survive early DSDT scan, skip it */
1227 static int ec_skip_dsdt_scan(const struct dmi_system_id *id)
1228 {
1229 	EC_FLAGS_SKIP_DSDT_SCAN = 1;
1230 	return 0;
1231 }
1232 
1233 /* ASUStek often supplies us with broken ECDT, validate it */
1234 static int ec_validate_ecdt(const struct dmi_system_id *id)
1235 {
1236 	EC_FLAGS_VALIDATE_ECDT = 1;
1237 	return 0;
1238 }
1239 
1240 /* MSI EC needs special treatment, enable it */
1241 static int ec_flag_msi(const struct dmi_system_id *id)
1242 {
1243 	pr_debug("Detected MSI hardware, enabling workarounds.\n");
1244 	EC_FLAGS_MSI = 1;
1245 	EC_FLAGS_VALIDATE_ECDT = 1;
1246 	return 0;
1247 }
1248 
1249 /*
1250  * Clevo M720 notebook actually works ok with IRQ mode, if we lifted
1251  * the GPE storm threshold back to 20
1252  */
1253 static int ec_enlarge_storm_threshold(const struct dmi_system_id *id)
1254 {
1255 	pr_debug("Setting the EC GPE storm threshold to 20\n");
1256 	ec_storm_threshold  = 20;
1257 	return 0;
1258 }
1259 
1260 /*
1261  * Acer EC firmware refuses to respond QR_EC when SCI_EVT is not set, for
1262  * which case, we complete the QR_EC without issuing it to the firmware.
1263  * https://bugzilla.kernel.org/show_bug.cgi?id=86211
1264  */
1265 static int ec_flag_query_handshake(const struct dmi_system_id *id)
1266 {
1267 	pr_debug("Detected the EC firmware requiring QR_EC issued when SCI_EVT set\n");
1268 	EC_FLAGS_QUERY_HANDSHAKE = 1;
1269 	return 0;
1270 }
1271 
1272 /*
1273  * On some hardware it is necessary to clear events accumulated by the EC during
1274  * sleep. These ECs stop reporting GPEs until they are manually polled, if too
1275  * many events are accumulated. (e.g. Samsung Series 5/9 notebooks)
1276  *
1277  * https://bugzilla.kernel.org/show_bug.cgi?id=44161
1278  *
1279  * Ideally, the EC should also be instructed NOT to accumulate events during
1280  * sleep (which Windows seems to do somehow), but the interface to control this
1281  * behaviour is not known at this time.
1282  *
1283  * Models known to be affected are Samsung 530Uxx/535Uxx/540Uxx/550Pxx/900Xxx,
1284  * however it is very likely that other Samsung models are affected.
1285  *
1286  * On systems which don't accumulate _Q events during sleep, this extra check
1287  * should be harmless.
1288  */
1289 static int ec_clear_on_resume(const struct dmi_system_id *id)
1290 {
1291 	pr_debug("Detected system needing EC poll on resume.\n");
1292 	EC_FLAGS_CLEAR_ON_RESUME = 1;
1293 	return 0;
1294 }
1295 
1296 static struct dmi_system_id ec_dmi_table[] __initdata = {
1297 	{
1298 	ec_skip_dsdt_scan, "Compal JFL92", {
1299 	DMI_MATCH(DMI_BIOS_VENDOR, "COMPAL"),
1300 	DMI_MATCH(DMI_BOARD_NAME, "JFL92") }, NULL},
1301 	{
1302 	ec_flag_msi, "MSI hardware", {
1303 	DMI_MATCH(DMI_BIOS_VENDOR, "Micro-Star")}, NULL},
1304 	{
1305 	ec_flag_msi, "MSI hardware", {
1306 	DMI_MATCH(DMI_SYS_VENDOR, "Micro-Star")}, NULL},
1307 	{
1308 	ec_flag_msi, "MSI hardware", {
1309 	DMI_MATCH(DMI_CHASSIS_VENDOR, "MICRO-Star")}, NULL},
1310 	{
1311 	ec_flag_msi, "MSI hardware", {
1312 	DMI_MATCH(DMI_CHASSIS_VENDOR, "MICRO-STAR")}, NULL},
1313 	{
1314 	ec_flag_msi, "Quanta hardware", {
1315 	DMI_MATCH(DMI_SYS_VENDOR, "Quanta"),
1316 	DMI_MATCH(DMI_PRODUCT_NAME, "TW8/SW8/DW8"),}, NULL},
1317 	{
1318 	ec_flag_msi, "Quanta hardware", {
1319 	DMI_MATCH(DMI_SYS_VENDOR, "Quanta"),
1320 	DMI_MATCH(DMI_PRODUCT_NAME, "TW9/SW9"),}, NULL},
1321 	{
1322 	ec_flag_msi, "Clevo W350etq", {
1323 	DMI_MATCH(DMI_SYS_VENDOR, "CLEVO CO."),
1324 	DMI_MATCH(DMI_PRODUCT_NAME, "W35_37ET"),}, NULL},
1325 	{
1326 	ec_validate_ecdt, "ASUS hardware", {
1327 	DMI_MATCH(DMI_BIOS_VENDOR, "ASUS") }, NULL},
1328 	{
1329 	ec_validate_ecdt, "ASUS hardware", {
1330 	DMI_MATCH(DMI_BOARD_VENDOR, "ASUSTeK Computer Inc.") }, NULL},
1331 	{
1332 	ec_enlarge_storm_threshold, "CLEVO hardware", {
1333 	DMI_MATCH(DMI_SYS_VENDOR, "CLEVO Co."),
1334 	DMI_MATCH(DMI_PRODUCT_NAME, "M720T/M730T"),}, NULL},
1335 	{
1336 	ec_skip_dsdt_scan, "HP Folio 13", {
1337 	DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
1338 	DMI_MATCH(DMI_PRODUCT_NAME, "HP Folio 13"),}, NULL},
1339 	{
1340 	ec_validate_ecdt, "ASUS hardware", {
1341 	DMI_MATCH(DMI_SYS_VENDOR, "ASUSTek Computer Inc."),
1342 	DMI_MATCH(DMI_PRODUCT_NAME, "L4R"),}, NULL},
1343 	{
1344 	ec_clear_on_resume, "Samsung hardware", {
1345 	DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD.")}, NULL},
1346 	{
1347 	ec_flag_query_handshake, "Acer hardware", {
1348 	DMI_MATCH(DMI_SYS_VENDOR, "Acer"), }, NULL},
1349 	{},
1350 };
1351 
1352 int __init acpi_ec_ecdt_probe(void)
1353 {
1354 	acpi_status status;
1355 	struct acpi_ec *saved_ec = NULL;
1356 	struct acpi_table_ecdt *ecdt_ptr;
1357 
1358 	boot_ec = make_acpi_ec();
1359 	if (!boot_ec)
1360 		return -ENOMEM;
1361 	/*
1362 	 * Generate a boot ec context
1363 	 */
1364 	dmi_check_system(ec_dmi_table);
1365 	status = acpi_get_table(ACPI_SIG_ECDT, 1,
1366 				(struct acpi_table_header **)&ecdt_ptr);
1367 	if (ACPI_SUCCESS(status)) {
1368 		pr_info("EC description table is found, configuring boot EC\n");
1369 		boot_ec->command_addr = ecdt_ptr->control.address;
1370 		boot_ec->data_addr = ecdt_ptr->data.address;
1371 		boot_ec->gpe = ecdt_ptr->gpe;
1372 		boot_ec->handle = ACPI_ROOT_OBJECT;
1373 		acpi_get_handle(ACPI_ROOT_OBJECT, ecdt_ptr->id,
1374 				&boot_ec->handle);
1375 		/* Don't trust ECDT, which comes from ASUSTek */
1376 		if (!EC_FLAGS_VALIDATE_ECDT)
1377 			goto install;
1378 		saved_ec = kmemdup(boot_ec, sizeof(struct acpi_ec), GFP_KERNEL);
1379 		if (!saved_ec)
1380 			return -ENOMEM;
1381 	/* fall through */
1382 	}
1383 
1384 	if (EC_FLAGS_SKIP_DSDT_SCAN) {
1385 		kfree(saved_ec);
1386 		return -ENODEV;
1387 	}
1388 
1389 	/* This workaround is needed only on some broken machines,
1390 	 * which require early EC, but fail to provide ECDT */
1391 	pr_debug("Look up EC in DSDT\n");
1392 	status = acpi_get_devices(ec_device_ids[0].id, ec_parse_device,
1393 					boot_ec, NULL);
1394 	/* Check that acpi_get_devices actually find something */
1395 	if (ACPI_FAILURE(status) || !boot_ec->handle)
1396 		goto error;
1397 	if (saved_ec) {
1398 		/* try to find good ECDT from ASUSTek */
1399 		if (saved_ec->command_addr != boot_ec->command_addr ||
1400 		    saved_ec->data_addr != boot_ec->data_addr ||
1401 		    saved_ec->gpe != boot_ec->gpe ||
1402 		    saved_ec->handle != boot_ec->handle)
1403 			pr_info("ASUSTek keeps feeding us with broken "
1404 			"ECDT tables, which are very hard to workaround. "
1405 			"Trying to use DSDT EC info instead. Please send "
1406 			"output of acpidump to linux-acpi@vger.kernel.org\n");
1407 		kfree(saved_ec);
1408 		saved_ec = NULL;
1409 	} else {
1410 		/* We really need to limit this workaround, the only ASUS,
1411 		* which needs it, has fake EC._INI method, so use it as flag.
1412 		* Keep boot_ec struct as it will be needed soon.
1413 		*/
1414 		if (!dmi_name_in_vendors("ASUS") ||
1415 		    !acpi_has_method(boot_ec->handle, "_INI"))
1416 			return -ENODEV;
1417 	}
1418 install:
1419 	if (!ec_install_handlers(boot_ec)) {
1420 		first_ec = boot_ec;
1421 		return 0;
1422 	}
1423 error:
1424 	kfree(boot_ec);
1425 	kfree(saved_ec);
1426 	boot_ec = NULL;
1427 	return -ENODEV;
1428 }
1429 
1430 static struct acpi_driver acpi_ec_driver = {
1431 	.name = "ec",
1432 	.class = ACPI_EC_CLASS,
1433 	.ids = ec_device_ids,
1434 	.ops = {
1435 		.add = acpi_ec_add,
1436 		.remove = acpi_ec_remove,
1437 		},
1438 };
1439 
1440 int __init acpi_ec_init(void)
1441 {
1442 	int result = 0;
1443 
1444 	/* Now register the driver for the EC */
1445 	result = acpi_bus_register_driver(&acpi_ec_driver);
1446 	if (result < 0)
1447 		return -ENODEV;
1448 
1449 	return result;
1450 }
1451 
1452 /* EC driver currently not unloadable */
1453 #if 0
1454 static void __exit acpi_ec_exit(void)
1455 {
1456 
1457 	acpi_bus_unregister_driver(&acpi_ec_driver);
1458 }
1459 #endif	/* 0 */
1460