summaryrefslogtreecommitdiffstats
path: root/drivers/acpi/acpi_ipmi.c
blob: ac0f52f6df2b862052a3de423ac039a6bd2eefe8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
/*
 *  acpi_ipmi.c - ACPI IPMI opregion
 *
 *  Copyright (C) 2010, 2013 Intel Corporation
 *    Author: Zhao Yakui <yakui.zhao@intel.com>
 *            Lv Zheng <lv.zheng@intel.com>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  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.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

#include <linux/module.h>
#include <linux/acpi.h>
#include <linux/ipmi.h>
#include <linux/spinlock.h>

MODULE_AUTHOR("Zhao Yakui");
MODULE_DESCRIPTION("ACPI IPMI Opregion driver");
MODULE_LICENSE("GPL");

#define ACPI_IPMI_OK			0
#define ACPI_IPMI_TIMEOUT		0x10
#define ACPI_IPMI_UNKNOWN		0x07
/* the IPMI timeout is 5s */
#define IPMI_TIMEOUT			(5000)
#define ACPI_IPMI_MAX_MSG_LENGTH	64

struct acpi_ipmi_device {
	/* the device list attached to driver_data.ipmi_devices */
	struct list_head head;

	/* the IPMI request message list */
	struct list_head tx_msg_list;

	spinlock_t tx_msg_lock;
	acpi_handle handle;
	struct device *dev;
	ipmi_user_t user_interface;
	int ipmi_ifnum; /* IPMI interface number */
	long curr_msgid;
	bool dead;
	struct kref kref;
};

struct ipmi_driver_data {
	struct list_head ipmi_devices;
	struct ipmi_smi_watcher bmc_events;
	struct ipmi_user_hndl ipmi_hndlrs;
	struct mutex ipmi_lock;

	/*
	 * NOTE: IPMI System Interface Selection
	 * There is no system interface specified by the IPMI operation
	 * region access.  We try to select one system interface with ACPI
	 * handle set.  IPMI messages passed from the ACPI codes are sent
	 * to this selected global IPMI system interface.
	 */
	struct acpi_ipmi_device *selected_smi;
};

struct acpi_ipmi_msg {
	struct list_head head;

	/*
	 * General speaking the addr type should be SI_ADDR_TYPE. And
	 * the addr channel should be BMC.
	 * In fact it can also be IPMB type. But we will have to
	 * parse it from the Netfn command buffer. It is so complex
	 * that it is skipped.
	 */
	struct ipmi_addr addr;
	long tx_msgid;

	/* it is used to track whether the IPMI message is finished */
	struct completion tx_complete;

	struct kernel_ipmi_msg tx_message;
	int msg_done;

	/* tx/rx data . And copy it from/to ACPI object buffer */
	u8 data[ACPI_IPMI_MAX_MSG_LENGTH];
	u8 rx_len;

	struct acpi_ipmi_device *device;
	struct kref kref;
};

/* IPMI request/response buffer per ACPI 4.0, sec 5.5.2.4.3.2 */
struct acpi_ipmi_buffer {
	u8 status;
	u8 length;
	u8 data[ACPI_IPMI_MAX_MSG_LENGTH];
};

static void ipmi_register_bmc(int iface, struct device *dev);
static void ipmi_bmc_gone(int iface);
static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data);

static struct ipmi_driver_data driver_data = {
	.ipmi_devices = LIST_HEAD_INIT(driver_data.ipmi_devices),
	.bmc_events = {
		.owner = THIS_MODULE,
		.new_smi = ipmi_register_bmc,
		.smi_gone = ipmi_bmc_gone,
	},
	.ipmi_hndlrs = {
		.ipmi_recv_hndl = ipmi_msg_handler,
	},
	.ipmi_lock = __MUTEX_INITIALIZER(driver_data.ipmi_lock)
};

static struct acpi_ipmi_device *
ipmi_dev_alloc(int iface, struct device *dev, acpi_handle handle)
{
	struct acpi_ipmi_device *ipmi_device;
	int err;
	ipmi_user_t user;

	ipmi_device = kzalloc(sizeof(*ipmi_device), GFP_KERNEL);
	if (!ipmi_device)
		return NULL;

	kref_init(&ipmi_device->kref);
	INIT_LIST_HEAD(&ipmi_device->head);
	INIT_LIST_HEAD(&ipmi_device->tx_msg_list);
	spin_lock_init(&ipmi_device->tx_msg_lock);
	ipmi_device->handle = handle;
	ipmi_device->dev = get_device(dev);
	ipmi_device->ipmi_ifnum = iface;

	err = ipmi_create_user(iface, &driver_data.ipmi_hndlrs,
			       ipmi_device, &user);
	if (err) {
		put_device(dev);
		kfree(ipmi_device);
		return NULL;
	}
	ipmi_device->user_interface = user;

	return ipmi_device;
}

static void ipmi_dev_release(struct acpi_ipmi_device *ipmi_device)
{
	ipmi_destroy_user(ipmi_device->user_interface);
	put_device(ipmi_device->dev);
	kfree(ipmi_device);
}

static void ipmi_dev_release_kref(struct kref *kref)
{
	struct acpi_ipmi_device *ipmi =
		container_of(kref, struct acpi_ipmi_device, kref);

	ipmi_dev_release(ipmi);
}

static void __ipmi_dev_kill(struct acpi_ipmi_device *ipmi_device)
{
	list_del(&ipmi_device->head);
	if (driver_data.selected_smi == ipmi_device)
		driver_data.selected_smi = NULL;

	/*
	 * Always setting dead flag after deleting from the list or
	 * list_for_each_entry() codes must get changed.
	 */
	ipmi_device->dead = true;
}

static struct acpi_ipmi_device *acpi_ipmi_dev_get(void)
{
	struct acpi_ipmi_device *ipmi_device = NULL;

	mutex_lock(&driver_data.ipmi_lock);
	if (driver_data.selected_smi) {
		ipmi_device = driver_data.selected_smi;
		kref_get(&ipmi_device->kref);
	}
	mutex_unlock(&driver_data.ipmi_lock);

	return ipmi_device;
}

static void acpi_ipmi_dev_put(struct acpi_ipmi_device *ipmi_device)
{
	kref_put(&ipmi_device->kref, ipmi_dev_release_kref);
}

static struct acpi_ipmi_msg *ipmi_msg_alloc(void)
{
	struct acpi_ipmi_device *ipmi;
	struct acpi_ipmi_msg *ipmi_msg;

	ipmi = acpi_ipmi_dev_get();
	if (!ipmi)
		return NULL;

	ipmi_msg = kzalloc(sizeof(struct acpi_ipmi_msg), GFP_KERNEL);
	if (!ipmi_msg) {
		acpi_ipmi_dev_put(ipmi);
		return NULL;
	}

	kref_init(&ipmi_msg->kref);
	init_completion(&ipmi_msg->tx_complete);
	INIT_LIST_HEAD(&ipmi_msg->head);
	ipmi_msg->device = ipmi;
	ipmi_msg->msg_done = ACPI_IPMI_UNKNOWN;

	return ipmi_msg;
}

static void ipmi_msg_release(struct acpi_ipmi_msg *tx_msg)
{
	acpi_ipmi_dev_put(tx_msg->device);
	kfree(tx_msg);
}

static void ipmi_msg_release_kref(struct kref *kref)
{
	struct acpi_ipmi_msg *tx_msg =
		container_of(kref, struct acpi_ipmi_msg, kref);

	ipmi_msg_release(tx_msg);
}

static struct acpi_ipmi_msg *acpi_ipmi_msg_get(struct acpi_ipmi_msg *tx_msg)
{
	kref_get(&tx_msg->kref);

	return tx_msg;
}

static void acpi_ipmi_msg_put(struct acpi_ipmi_msg *tx_msg)
{
	kref_put(&tx_msg->kref, ipmi_msg_release_kref);
}

#define IPMI_OP_RGN_NETFN(offset)	((offset >> 8) & 0xff)
#define IPMI_OP_RGN_CMD(offset)		(offset & 0xff)
static int acpi_format_ipmi_request(struct acpi_ipmi_msg *tx_msg,
				    acpi_physical_address address,
				    acpi_integer *value)
{
	struct kernel_ipmi_msg *msg;
	struct acpi_ipmi_buffer *buffer;
	struct acpi_ipmi_device *device;
	unsigned long flags;

	msg = &tx_msg->tx_message;

	/*
	 * IPMI network function and command are encoded in the address
	 * within the IPMI OpRegion; see ACPI 4.0, sec 5.5.2.4.3.
	 */
	msg->netfn = IPMI_OP_RGN_NETFN(address);
	msg->cmd = IPMI_OP_RGN_CMD(address);
	msg->data = tx_msg->data;

	/*
	 * value is the parameter passed by the IPMI opregion space handler.
	 * It points to the IPMI request message buffer
	 */
	buffer = (struct acpi_ipmi_buffer *)value;

	/* copy the tx message data */
	if (buffer->length > ACPI_IPMI_MAX_MSG_LENGTH) {
		dev_WARN_ONCE(tx_msg->device->dev, true,
			      "Unexpected request (msg len %d).\n",
			      buffer->length);
		return -EINVAL;
	}
	msg->data_len = buffer->length;
	memcpy(tx_msg->data, buffer->data, msg->data_len);

	/*
	 * now the default type is SYSTEM_INTERFACE and channel type is BMC.
	 * If the netfn is APP_REQUEST and the cmd is SEND_MESSAGE,
	 * the addr type should be changed to IPMB. Then we will have to parse
	 * the IPMI request message buffer to get the IPMB address.
	 * If so, please fix me.
	 */
	tx_msg->addr.addr_type = IPMI_SYSTEM_INTERFACE_ADDR_TYPE;
	tx_msg->addr.channel = IPMI_BMC_CHANNEL;
	tx_msg->addr.data[0] = 0;

	/* Get the msgid */
	device = tx_msg->device;

	spin_lock_irqsave(&device->tx_msg_lock, flags);
	device->curr_msgid++;
	tx_msg->tx_msgid = device->curr_msgid;
	spin_unlock_irqrestore(&device->tx_msg_lock, flags);

	return 0;
}

static void acpi_format_ipmi_response(struct acpi_ipmi_msg *msg,
				      acpi_integer *value)
{
	struct acpi_ipmi_buffer *buffer;

	/*
	 * value is also used as output parameter. It represents the response
	 * IPMI message returned by IPMI command.
	 */
	buffer = (struct acpi_ipmi_buffer *)value;

	/*
	 * If the flag of msg_done is not set, it means that the IPMI command is
	 * not executed correctly.
	 */
	buffer->status = msg->msg_done;
	if (msg->msg_done != ACPI_IPMI_OK)
		return;

	/*
	 * If the IPMI response message is obtained correctly, the status code
	 * will be ACPI_IPMI_OK
	 */
	buffer->length = msg->rx_len;
	memcpy(buffer->data, msg->data, msg->rx_len);
}

static void ipmi_flush_tx_msg(struct acpi_ipmi_device *ipmi)
{
	struct acpi_ipmi_msg *tx_msg;
	unsigned long flags;

	/*
	 * NOTE: On-going ipmi_recv_msg
	 * ipmi_msg_handler() may still be invoked by ipmi_si after
	 * flushing.  But it is safe to do a fast flushing on module_exit()
	 * without waiting for all ipmi_recv_msg(s) to complete from
	 * ipmi_msg_handler() as it is ensured by ipmi_si that all
	 * ipmi_recv_msg(s) are freed after invoking ipmi_destroy_user().
	 */
	spin_lock_irqsave(&ipmi->tx_msg_lock, flags);
	while (!list_empty(&ipmi->tx_msg_list)) {
		tx_msg = list_first_entry(&ipmi->tx_msg_list,
					  struct acpi_ipmi_msg,
					  head);
		list_del(&tx_msg->head);
		spin_unlock_irqrestore(&ipmi->tx_msg_lock, flags);

		/* wake up the sleep thread on the Tx msg */
		complete(&tx_msg->tx_complete);
		acpi_ipmi_msg_put(tx_msg);
		spin_lock_irqsave(&ipmi->tx_msg_lock, flags);
	}
	spin_unlock_irqrestore(&ipmi->tx_msg_lock, flags);
}

static void ipmi_cancel_tx_msg(struct acpi_ipmi_device *ipmi,
			       struct acpi_ipmi_msg *msg)
{
	struct acpi_ipmi_msg *tx_msg, *temp;
	bool msg_found = false;
	unsigned long flags;

	spin_lock_irqsave(&ipmi->tx_msg_lock, flags);
	list_for_each_entry_safe(tx_msg, temp, &ipmi->tx_msg_list, head) {
		if (msg == tx_msg) {
			msg_found = true;
			list_del(&tx_msg->head);
			break;
		}
	}
	spin_unlock_irqrestore(&ipmi->tx_msg_lock, flags);

	if (msg_found)
		acpi_ipmi_msg_put(tx_msg);
}

static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data)
{
	struct acpi_ipmi_device *ipmi_device = user_msg_data;
	bool msg_found = false;
	struct acpi_ipmi_msg *tx_msg, *temp;
	struct device *dev = ipmi_device->dev;
	unsigned long flags;

	if (msg->user != ipmi_device->user_interface) {
		dev_warn(dev,
			 "Unexpected response is returned. returned user %p, expected user %p\n",
			 msg->user, ipmi_device->user_interface);
		goto out_msg;
	}

	spin_lock_irqsave(&ipmi_device->tx_msg_lock, flags);
	list_for_each_entry_safe(tx_msg, temp, &ipmi_device->tx_msg_list, head) {
		if (msg->msgid == tx_msg->tx_msgid) {
			msg_found = true;
			list_del(&tx_msg->head);
			break;
		}
	}
	spin_unlock_irqrestore(&ipmi_device->tx_msg_lock, flags);

	if (!msg_found) {
		dev_warn(dev,
			 "Unexpected response (msg id %ld) is returned.\n",
			 msg->msgid);
		goto out_msg;
	}

	/* copy the response data to Rx_data buffer */
	if (msg->msg.data_len > ACPI_IPMI_MAX_MSG_LENGTH) {
		dev_WARN_ONCE(dev, true,
			      "Unexpected response (msg len %d).\n",
			      msg->msg.data_len);
		goto out_comp;
	}

	/* response msg is an error msg */
	msg->recv_type = IPMI_RESPONSE_RECV_TYPE;
	if (msg->recv_type == IPMI_RESPONSE_RECV_TYPE &&
	    msg->msg.data_len == 1) {
		if (msg->msg.data[0] == IPMI_TIMEOUT_COMPLETION_CODE) {
			dev_WARN_ONCE(dev, true,
				      "Unexpected response (timeout).\n");
			tx_msg->msg_done = ACPI_IPMI_TIMEOUT;
		}
		goto out_comp;
	}

	tx_msg->rx_len = msg->msg.data_len;
	memcpy(tx_msg->data, msg->msg.data, tx_msg->rx_len);
	tx_msg->msg_done = ACPI_IPMI_OK;

out_comp:
	complete(&tx_msg->tx_complete);
	acpi_ipmi_msg_put(tx_msg);
out_msg:
	ipmi_free_recv_msg(msg);
}

static void ipmi_register_bmc(int iface, struct device *dev)
{
	struct acpi_ipmi_device *ipmi_device, *temp;
	int err;
	struct ipmi_smi_info smi_data;
	acpi_handle handle;

	err = ipmi_get_smi_info(iface, &smi_data);
	if (err)
		return;

	if (smi_data.addr_src != SI_ACPI)
		goto err_ref;
	handle = smi_data.addr_info.acpi_info.acpi_handle;
	if (!handle)
		goto err_ref;

	ipmi_device = ipmi_dev_alloc(iface, smi_data.dev, handle);
	if (!ipmi_device) {
		dev_warn(smi_data.dev, "Can't create IPMI user interface\n");
		goto err_ref;
	}

	mutex_lock(&driver_data.ipmi_lock);
	list_for_each_entry(temp, &driver_data.ipmi_devices, head) {
		/*
		 * if the corresponding ACPI handle is already added
		 * to the device list, don't add it again.
		 */
		if (temp->handle == handle)
			goto err_lock;
	}
	if (!driver_data.selected_smi)
		driver_data.selected_smi = ipmi_device;
	list_add_tail(&ipmi_device->head, &driver_data.ipmi_devices);
	mutex_unlock(&driver_data.ipmi_lock);

	put_device(smi_data.dev);
	return;

err_lock:
	mutex_unlock(&driver_data.ipmi_lock);
	ipmi_dev_release(ipmi_device);
err_ref:
	put_device(smi_data.dev);
	return;
}

static void ipmi_bmc_gone(int iface)
{
	struct acpi_ipmi_device *ipmi_device, *temp;
	bool dev_found = false;

	mutex_lock(&driver_data.ipmi_lock);
	list_for_each_entry_safe(ipmi_device, temp,
				 &driver_data.ipmi_devices, head) {
		if (ipmi_device->ipmi_ifnum != iface) {
			dev_found = true;
			__ipmi_dev_kill(ipmi_device);
			break;
		}
	}
	if (!driver_data.selected_smi)
		driver_data.selected_smi = list_first_entry_or_null(
					&driver_data.ipmi_devices,
					struct acpi_ipmi_device, head);
	mutex_unlock(&driver_data.ipmi_lock);

	if (dev_found) {
		ipmi_flush_tx_msg(ipmi_device);
		acpi_ipmi_dev_put(ipmi_device);
	}
}

/*
 * This is the IPMI opregion space handler.
 * @function: indicates the read/write. In fact as the IPMI message is driven
 * by command, only write is meaningful.
 * @address: This contains the netfn/command of IPMI request message.
 * @bits   : not used.
 * @value  : it is an in/out parameter. It points to the IPMI message buffer.
 *	     Before the IPMI message is sent, it represents the actual request
 *	     IPMI message. After the IPMI message is finished, it represents
 *	     the response IPMI message returned by IPMI command.
 * @handler_context: IPMI device context.
 */
static acpi_status
acpi_ipmi_space_handler(u32 function, acpi_physical_address address,
			u32 bits, acpi_integer *value,
			void *handler_context, void *region_context)
{
	struct acpi_ipmi_msg *tx_msg;
	struct acpi_ipmi_device *ipmi_device;
	int err;
	acpi_status status;
	unsigned long flags;

	/*
	 * IPMI opregion message.
	 * IPMI message is firstly written to the BMC and system software
	 * can get the respsonse. So it is unmeaningful for the read access
	 * of IPMI opregion.
	 */
	if ((function & ACPI_IO_MASK) == ACPI_READ)
		return AE_TYPE;

	tx_msg = ipmi_msg_alloc();
	if (!tx_msg)
		return AE_NOT_EXIST;
	ipmi_device = tx_msg->device;

	if (acpi_format_ipmi_request(tx_msg, address, value) != 0) {
		ipmi_msg_release(tx_msg);
		return AE_TYPE;
	}

	acpi_ipmi_msg_get(tx_msg);
	mutex_lock(&driver_data.ipmi_lock);
	/* Do not add a tx_msg that can not be flushed. */
	if (ipmi_device->dead) {
		mutex_unlock(&driver_data.ipmi_lock);
		ipmi_msg_release(tx_msg);
		return AE_NOT_EXIST;
	}
	spin_lock_irqsave(&ipmi_device->tx_msg_lock, flags);
	list_add_tail(&tx_msg->head, &ipmi_device->tx_msg_list);
	spin_unlock_irqrestore(&ipmi_device->tx_msg_lock, flags);
	mutex_unlock(&driver_data.ipmi_lock);

	err = ipmi_request_settime(ipmi_device->user_interface,
				   &tx_msg->addr,
				   tx_msg->tx_msgid,
				   &tx_msg->tx_message,
				   NULL, 0, 0, IPMI_TIMEOUT);
	if (err) {
		status = AE_ERROR;
		goto out_msg;
	}
	wait_for_completion(&tx_msg->tx_complete);

	acpi_format_ipmi_response(tx_msg, value);
	status = AE_OK;

out_msg:
	ipmi_cancel_tx_msg(ipmi_device, tx_msg);
	acpi_ipmi_msg_put(tx_msg);
	return status;
}

static int __init acpi_ipmi_init(void)
{
	int result;
	acpi_status status;

	if (acpi_disabled)
		return 0;

	status = acpi_install_address_space_handler(ACPI_ROOT_OBJECT,
						    ACPI_ADR_SPACE_IPMI,
						    &acpi_ipmi_space_handler,
						    NULL, NULL);
	if (ACPI_FAILURE(status)) {
		pr_warn("Can't register IPMI opregion space handle\n");
		return -EINVAL;
	}
	result = ipmi_smi_watcher_register(&driver_data.bmc_events);
	if (result)
		pr_err("Can't register IPMI system interface watcher\n");

	return result;
}

static void __exit acpi_ipmi_exit(void)
{
	struct acpi_ipmi_device *ipmi_device;

	if (acpi_disabled)
		return;

	ipmi_smi_watcher_unregister(&driver_data.bmc_events);

	/*
	 * When one smi_watcher is unregistered, it is only deleted
	 * from the smi_watcher list. But the smi_gone callback function
	 * is not called. So explicitly uninstall the ACPI IPMI oregion
	 * handler and free it.
	 */
	mutex_lock(&driver_data.ipmi_lock);
	while (!list_empty(&driver_data.ipmi_devices)) {
		ipmi_device = list_first_entry(&driver_data.ipmi_devices,
					       struct acpi_ipmi_device,
					       head);
		__ipmi_dev_kill(ipmi_device);
		mutex_unlock(&driver_data.ipmi_lock);

		ipmi_flush_tx_msg(ipmi_device);
		acpi_ipmi_dev_put(ipmi_device);

		mutex_lock(&driver_data.ipmi_lock);
	}
	mutex_unlock(&driver_data.ipmi_lock);
	acpi_remove_address_space_handler(ACPI_ROOT_OBJECT,
					  ACPI_ADR_SPACE_IPMI,
					  &acpi_ipmi_space_handler);
}

module_init(acpi_ipmi_init);
module_exit(acpi_ipmi_exit);
OpenPOWER on IntegriCloud