summaryrefslogtreecommitdiff
path: root/drivers/firmware/google/gsmi.c
blob: edaa4e5d84ade0a65b89c8d186c0c0195b49ddfc (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
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright 2010 Google Inc. All Rights Reserved.
 * Author: dlaurie@google.com (Duncan Laurie)
 *
 * Re-worked to expose sysfs APIs by mikew@google.com (Mike Waychison)
 *
 * EFI SMI interface for Google platforms
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/spinlock.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/ioctl.h>
#include <linux/acpi.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/dmi.h>
#include <linux/kdebug.h>
#include <linux/reboot.h>
#include <linux/efi.h>
#include <linux/module.h>
#include <linux/ucs2_string.h>
#include <linux/suspend.h>

#define GSMI_SHUTDOWN_CLEAN	0	/* Clean Shutdown */
/* TODO(mikew@google.com): Tie in HARDLOCKUP_DETECTOR with NMIWDT */
#define GSMI_SHUTDOWN_NMIWDT	1	/* NMI Watchdog */
#define GSMI_SHUTDOWN_PANIC	2	/* Panic */
#define GSMI_SHUTDOWN_OOPS	3	/* Oops */
#define GSMI_SHUTDOWN_DIE	4	/* Die -- No longer meaningful */
#define GSMI_SHUTDOWN_MCE	5	/* Machine Check */
#define GSMI_SHUTDOWN_SOFTWDT	6	/* Software Watchdog */
#define GSMI_SHUTDOWN_MBE	7	/* Uncorrected ECC */
#define GSMI_SHUTDOWN_TRIPLE	8	/* Triple Fault */

#define DRIVER_VERSION		"1.0"
#define GSMI_GUID_SIZE		16
#define GSMI_BUF_SIZE		1024
#define GSMI_BUF_ALIGN		sizeof(u64)
#define GSMI_CALLBACK		0xef

/* SMI return codes */
#define GSMI_SUCCESS		0x00
#define GSMI_UNSUPPORTED2	0x03
#define GSMI_LOG_FULL		0x0b
#define GSMI_VAR_NOT_FOUND	0x0e
#define GSMI_HANDSHAKE_SPIN	0x7d
#define GSMI_HANDSHAKE_CF	0x7e
#define GSMI_HANDSHAKE_NONE	0x7f
#define GSMI_INVALID_PARAMETER	0x82
#define GSMI_UNSUPPORTED	0x83
#define GSMI_BUFFER_TOO_SMALL	0x85
#define GSMI_NOT_READY		0x86
#define GSMI_DEVICE_ERROR	0x87
#define GSMI_NOT_FOUND		0x8e

#define QUIRKY_BOARD_HASH 0x78a30a50

/* Internally used commands passed to the firmware */
#define GSMI_CMD_GET_NVRAM_VAR		0x01
#define GSMI_CMD_GET_NEXT_VAR		0x02
#define GSMI_CMD_SET_NVRAM_VAR		0x03
#define GSMI_CMD_SET_EVENT_LOG		0x08
#define GSMI_CMD_CLEAR_EVENT_LOG	0x09
#define GSMI_CMD_LOG_S0IX_SUSPEND	0x0a
#define GSMI_CMD_LOG_S0IX_RESUME	0x0b
#define GSMI_CMD_CLEAR_CONFIG		0x20
#define GSMI_CMD_HANDSHAKE_TYPE		0xC1

/* Magic entry type for kernel events */
#define GSMI_LOG_ENTRY_TYPE_KERNEL     0xDEAD

/* SMI buffers must be in 32bit physical address space */
struct gsmi_buf {
	u8 *start;			/* start of buffer */
	size_t length;			/* length of buffer */
	dma_addr_t handle;		/* dma allocation handle */
	u32 address;			/* physical address of buffer */
};

static struct gsmi_device {
	struct platform_device *pdev;	/* platform device */
	struct gsmi_buf *name_buf;	/* variable name buffer */
	struct gsmi_buf *data_buf;	/* generic data buffer */
	struct gsmi_buf *param_buf;	/* parameter buffer */
	spinlock_t lock;		/* serialize access to SMIs */
	u16 smi_cmd;			/* SMI command port */
	int handshake_type;		/* firmware handler interlock type */
	struct dma_pool *dma_pool;	/* DMA buffer pool */
} gsmi_dev;

/* Packed structures for communicating with the firmware */
struct gsmi_nvram_var_param {
	efi_guid_t	guid;
	u32		name_ptr;
	u32		attributes;
	u32		data_len;
	u32		data_ptr;
} __packed;

struct gsmi_get_next_var_param {
	u8	guid[GSMI_GUID_SIZE];
	u32	name_ptr;
	u32	name_len;
} __packed;

struct gsmi_set_eventlog_param {
	u32	data_ptr;
	u32	data_len;
	u32	type;
} __packed;

/* Event log formats */
struct gsmi_log_entry_type_1 {
	u16	type;
	u32	instance;
} __packed;

/*
 * Some platforms don't have explicit SMI handshake
 * and need to wait for SMI to complete.
 */
#define GSMI_DEFAULT_SPINCOUNT	0x10000
static unsigned int spincount = GSMI_DEFAULT_SPINCOUNT;
module_param(spincount, uint, 0600);
MODULE_PARM_DESC(spincount,
	"The number of loop iterations to use when using the spin handshake.");

/*
 * Platforms might not support S0ix logging in their GSMI handlers. In order to
 * avoid any side-effects of generating an SMI for S0ix logging, use the S0ix
 * related GSMI commands only for those platforms that explicitly enable this
 * option.
 */
static bool s0ix_logging_enable;
module_param(s0ix_logging_enable, bool, 0600);

static struct gsmi_buf *gsmi_buf_alloc(void)
{
	struct gsmi_buf *smibuf;

	smibuf = kzalloc(sizeof(*smibuf), GFP_KERNEL);
	if (!smibuf) {
		printk(KERN_ERR "gsmi: out of memory\n");
		return NULL;
	}

	/* allocate buffer in 32bit address space */
	smibuf->start = dma_pool_alloc(gsmi_dev.dma_pool, GFP_KERNEL,
				       &smibuf->handle);
	if (!smibuf->start) {
		printk(KERN_ERR "gsmi: failed to allocate name buffer\n");
		kfree(smibuf);
		return NULL;
	}

	/* fill in the buffer handle */
	smibuf->length = GSMI_BUF_SIZE;
	smibuf->address = (u32)virt_to_phys(smibuf->start);

	return smibuf;
}

static void gsmi_buf_free(struct gsmi_buf *smibuf)
{
	if (smibuf) {
		if (smibuf->start)
			dma_pool_free(gsmi_dev.dma_pool, smibuf->start,
				      smibuf->handle);
		kfree(smibuf);
	}
}

/*
 * Make a call to gsmi func(sub).  GSMI error codes are translated to
 * in-kernel errnos (0 on success, -ERRNO on error).
 */
static int gsmi_exec(u8 func, u8 sub)
{
	u16 cmd = (sub << 8) | func;
	u16 result = 0;
	int rc = 0;

	/*
	 * AH  : Subfunction number
	 * AL  : Function number
	 * EBX : Parameter block address
	 * DX  : SMI command port
	 *
	 * Three protocols here. See also the comment in gsmi_init().
	 */
	if (gsmi_dev.handshake_type == GSMI_HANDSHAKE_CF) {
		/*
		 * If handshake_type == HANDSHAKE_CF then set CF on the
		 * way in and wait for the handler to clear it; this avoids
		 * corrupting register state on those chipsets which have
		 * a delay between writing the SMI trigger register and
		 * entering SMM.
		 */
		asm volatile (
			"stc\n"
			"outb %%al, %%dx\n"
		"1:      jc 1b\n"
			: "=a" (result)
			: "0" (cmd),
			  "d" (gsmi_dev.smi_cmd),
			  "b" (gsmi_dev.param_buf->address)
			: "memory", "cc"
		);
	} else if (gsmi_dev.handshake_type == GSMI_HANDSHAKE_SPIN) {
		/*
		 * If handshake_type == HANDSHAKE_SPIN we spin a
		 * hundred-ish usecs to ensure the SMI has triggered.
		 */
		asm volatile (
			"outb %%al, %%dx\n"
		"1:      loop 1b\n"
			: "=a" (result)
			: "0" (cmd),
			  "d" (gsmi_dev.smi_cmd),
			  "b" (gsmi_dev.param_buf->address),
			  "c" (spincount)
			: "memory", "cc"
		);
	} else {
		/*
		 * If handshake_type == HANDSHAKE_NONE we do nothing;
		 * either we don't need to or it's legacy firmware that
		 * doesn't understand the CF protocol.
		 */
		asm volatile (
			"outb %%al, %%dx\n\t"
			: "=a" (result)
			: "0" (cmd),
			  "d" (gsmi_dev.smi_cmd),
			  "b" (gsmi_dev.param_buf->address)
			: "memory", "cc"
		);
	}

	/* check return code from SMI handler */
	switch (result) {
	case GSMI_SUCCESS:
		break;
	case GSMI_VAR_NOT_FOUND:
		/* not really an error, but let the caller know */
		rc = 1;
		break;
	case GSMI_INVALID_PARAMETER:
		printk(KERN_ERR "gsmi: exec 0x%04x: Invalid parameter\n", cmd);
		rc = -EINVAL;
		break;
	case GSMI_BUFFER_TOO_SMALL:
		printk(KERN_ERR "gsmi: exec 0x%04x: Buffer too small\n", cmd);
		rc = -ENOMEM;
		break;
	case GSMI_UNSUPPORTED:
	case GSMI_UNSUPPORTED2:
		if (sub != GSMI_CMD_HANDSHAKE_TYPE)
			printk(KERN_ERR "gsmi: exec 0x%04x: Not supported\n",
			       cmd);
		rc = -ENOSYS;
		break;
	case GSMI_NOT_READY:
		printk(KERN_ERR "gsmi: exec 0x%04x: Not ready\n", cmd);
		rc = -EBUSY;
		break;
	case GSMI_DEVICE_ERROR:
		printk(KERN_ERR "gsmi: exec 0x%04x: Device error\n", cmd);
		rc = -EFAULT;
		break;
	case GSMI_NOT_FOUND:
		printk(KERN_ERR "gsmi: exec 0x%04x: Data not found\n", cmd);
		rc = -ENOENT;
		break;
	case GSMI_LOG_FULL:
		printk(KERN_ERR "gsmi: exec 0x%04x: Log full\n", cmd);
		rc = -ENOSPC;
		break;
	case GSMI_HANDSHAKE_CF:
	case GSMI_HANDSHAKE_SPIN:
	case GSMI_HANDSHAKE_NONE:
		rc = result;
		break;
	default:
		printk(KERN_ERR "gsmi: exec 0x%04x: Unknown error 0x%04x\n",
		       cmd, result);
		rc = -ENXIO;
	}

	return rc;
}

#ifdef CONFIG_EFI_VARS

static struct efivars efivars;

static efi_status_t gsmi_get_variable(efi_char16_t *name,
				      efi_guid_t *vendor, u32 *attr,
				      unsigned long *data_size,
				      void *data)
{
	struct gsmi_nvram_var_param param = {
		.name_ptr = gsmi_dev.name_buf->address,
		.data_ptr = gsmi_dev.data_buf->address,
		.data_len = (u32)*data_size,
	};
	efi_status_t ret = EFI_SUCCESS;
	unsigned long flags;
	size_t name_len = ucs2_strnlen(name, GSMI_BUF_SIZE / 2);
	int rc;

	if (name_len >= GSMI_BUF_SIZE / 2)
		return EFI_BAD_BUFFER_SIZE;

	spin_lock_irqsave(&gsmi_dev.lock, flags);

	/* Vendor guid */
	memcpy(&param.guid, vendor, sizeof(param.guid));

	/* variable name, already in UTF-16 */
	memset(gsmi_dev.name_buf->start, 0, gsmi_dev.name_buf->length);
	memcpy(gsmi_dev.name_buf->start, name, name_len * 2);

	/* data pointer */
	memset(gsmi_dev.data_buf->start, 0, gsmi_dev.data_buf->length);

	/* parameter buffer */
	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));

	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_GET_NVRAM_VAR);
	if (rc < 0) {
		printk(KERN_ERR "gsmi: Get Variable failed\n");
		ret = EFI_LOAD_ERROR;
	} else if (rc == 1) {
		/* variable was not found */
		ret = EFI_NOT_FOUND;
	} else {
		/* Get the arguments back */
		memcpy(&param, gsmi_dev.param_buf->start, sizeof(param));

		/* The size reported is the min of all of our buffers */
		*data_size = min_t(unsigned long, *data_size,
						gsmi_dev.data_buf->length);
		*data_size = min_t(unsigned long, *data_size, param.data_len);

		/* Copy data back to return buffer. */
		memcpy(data, gsmi_dev.data_buf->start, *data_size);

		/* All variables are have the following attributes */
		*attr = EFI_VARIABLE_NON_VOLATILE |
			EFI_VARIABLE_BOOTSERVICE_ACCESS |
			EFI_VARIABLE_RUNTIME_ACCESS;
	}

	spin_unlock_irqrestore(&gsmi_dev.lock, flags);

	return ret;
}

static efi_status_t gsmi_get_next_variable(unsigned long *name_size,
					   efi_char16_t *name,
					   efi_guid_t *vendor)
{
	struct gsmi_get_next_var_param param = {
		.name_ptr = gsmi_dev.name_buf->address,
		.name_len = gsmi_dev.name_buf->length,
	};
	efi_status_t ret = EFI_SUCCESS;
	int rc;
	unsigned long flags;

	/* For the moment, only support buffers that exactly match in size */
	if (*name_size != GSMI_BUF_SIZE)
		return EFI_BAD_BUFFER_SIZE;

	/* Let's make sure the thing is at least null-terminated */
	if (ucs2_strnlen(name, GSMI_BUF_SIZE / 2) == GSMI_BUF_SIZE / 2)
		return EFI_INVALID_PARAMETER;

	spin_lock_irqsave(&gsmi_dev.lock, flags);

	/* guid */
	memcpy(&param.guid, vendor, sizeof(param.guid));

	/* variable name, already in UTF-16 */
	memcpy(gsmi_dev.name_buf->start, name, *name_size);

	/* parameter buffer */
	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));

	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_GET_NEXT_VAR);
	if (rc < 0) {
		printk(KERN_ERR "gsmi: Get Next Variable Name failed\n");
		ret = EFI_LOAD_ERROR;
	} else if (rc == 1) {
		/* variable not found -- end of list */
		ret = EFI_NOT_FOUND;
	} else {
		/* copy variable data back to return buffer */
		memcpy(&param, gsmi_dev.param_buf->start, sizeof(param));

		/* Copy the name back */
		memcpy(name, gsmi_dev.name_buf->start, GSMI_BUF_SIZE);
		*name_size = ucs2_strnlen(name, GSMI_BUF_SIZE / 2) * 2;

		/* copy guid to return buffer */
		memcpy(vendor, &param.guid, sizeof(param.guid));
		ret = EFI_SUCCESS;
	}

	spin_unlock_irqrestore(&gsmi_dev.lock, flags);

	return ret;
}

static efi_status_t gsmi_set_variable(efi_char16_t *name,
				      efi_guid_t *vendor,
				      u32 attr,
				      unsigned long data_size,
				      void *data)
{
	struct gsmi_nvram_var_param param = {
		.name_ptr = gsmi_dev.name_buf->address,
		.data_ptr = gsmi_dev.data_buf->address,
		.data_len = (u32)data_size,
		.attributes = EFI_VARIABLE_NON_VOLATILE |
			      EFI_VARIABLE_BOOTSERVICE_ACCESS |
			      EFI_VARIABLE_RUNTIME_ACCESS,
	};
	size_t name_len = ucs2_strnlen(name, GSMI_BUF_SIZE / 2);
	efi_status_t ret = EFI_SUCCESS;
	int rc;
	unsigned long flags;

	if (name_len >= GSMI_BUF_SIZE / 2)
		return EFI_BAD_BUFFER_SIZE;

	spin_lock_irqsave(&gsmi_dev.lock, flags);

	/* guid */
	memcpy(&param.guid, vendor, sizeof(param.guid));

	/* variable name, already in UTF-16 */
	memset(gsmi_dev.name_buf->start, 0, gsmi_dev.name_buf->length);
	memcpy(gsmi_dev.name_buf->start, name, name_len * 2);

	/* data pointer */
	memset(gsmi_dev.data_buf->start, 0, gsmi_dev.data_buf->length);
	memcpy(gsmi_dev.data_buf->start, data, data_size);

	/* parameter buffer */
	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));

	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_SET_NVRAM_VAR);
	if (rc < 0) {
		printk(KERN_ERR "gsmi: Set Variable failed\n");
		ret = EFI_INVALID_PARAMETER;
	}

	spin_unlock_irqrestore(&gsmi_dev.lock, flags);

	return ret;
}

static const struct efivar_operations efivar_ops = {
	.get_variable = gsmi_get_variable,
	.set_variable = gsmi_set_variable,
	.get_next_variable = gsmi_get_next_variable,
};

#endif /* CONFIG_EFI_VARS */

static ssize_t eventlog_write(struct file *filp, struct kobject *kobj,
			       struct bin_attribute *bin_attr,
			       char *buf, loff_t pos, size_t count)
{
	struct gsmi_set_eventlog_param param = {
		.data_ptr = gsmi_dev.data_buf->address,
	};
	int rc = 0;
	unsigned long flags;

	/* Pull the type out */
	if (count < sizeof(u32))
		return -EINVAL;
	param.type = *(u32 *)buf;
	buf += sizeof(u32);

	/* The remaining buffer is the data payload */
	if ((count - sizeof(u32)) > gsmi_dev.data_buf->length)
		return -EINVAL;
	param.data_len = count - sizeof(u32);

	spin_lock_irqsave(&gsmi_dev.lock, flags);

	/* data pointer */
	memset(gsmi_dev.data_buf->start, 0, gsmi_dev.data_buf->length);
	memcpy(gsmi_dev.data_buf->start, buf, param.data_len);

	/* parameter buffer */
	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));

	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_SET_EVENT_LOG);
	if (rc < 0)
		printk(KERN_ERR "gsmi: Set Event Log failed\n");

	spin_unlock_irqrestore(&gsmi_dev.lock, flags);

	return (rc == 0) ? count : rc;

}

static struct bin_attribute eventlog_bin_attr = {
	.attr = {.name = "append_to_eventlog", .mode = 0200},
	.write = eventlog_write,
};

static ssize_t gsmi_clear_eventlog_store(struct kobject *kobj,
					 struct kobj_attribute *attr,
					 const char *buf, size_t count)
{
	int rc;
	unsigned long flags;
	unsigned long val;
	struct {
		u32 percentage;
		u32 data_type;
	} param;

	rc = kstrtoul(buf, 0, &val);
	if (rc)
		return rc;

	/*
	 * Value entered is a percentage, 0 through 100, anything else
	 * is invalid.
	 */
	if (val > 100)
		return -EINVAL;

	/* data_type here selects the smbios event log. */
	param.percentage = val;
	param.data_type = 0;

	spin_lock_irqsave(&gsmi_dev.lock, flags);

	/* parameter buffer */
	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));

	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_CLEAR_EVENT_LOG);

	spin_unlock_irqrestore(&gsmi_dev.lock, flags);

	if (rc)
		return rc;
	return count;
}

static struct kobj_attribute gsmi_clear_eventlog_attr = {
	.attr = {.name = "clear_eventlog", .mode = 0200},
	.store = gsmi_clear_eventlog_store,
};

static ssize_t gsmi_clear_config_store(struct kobject *kobj,
				       struct kobj_attribute *attr,
				       const char *buf, size_t count)
{
	int rc;
	unsigned long flags;

	spin_lock_irqsave(&gsmi_dev.lock, flags);

	/* clear parameter buffer */
	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);

	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_CLEAR_CONFIG);

	spin_unlock_irqrestore(&gsmi_dev.lock, flags);

	if (rc)
		return rc;
	return count;
}

static struct kobj_attribute gsmi_clear_config_attr = {
	.attr = {.name = "clear_config", .mode = 0200},
	.store = gsmi_clear_config_store,
};

static const struct attribute *gsmi_attrs[] = {
	&gsmi_clear_config_attr.attr,
	&gsmi_clear_eventlog_attr.attr,
	NULL,
};

static int gsmi_shutdown_reason(int reason)
{
	struct gsmi_log_entry_type_1 entry = {
		.type     = GSMI_LOG_ENTRY_TYPE_KERNEL,
		.instance = reason,
	};
	struct gsmi_set_eventlog_param param = {
		.data_len = sizeof(entry),
		.type     = 1,
	};
	static int saved_reason;
	int rc = 0;
	unsigned long flags;

	/* avoid duplicate entries in the log */
	if (saved_reason & (1 << reason))
		return 0;

	spin_lock_irqsave(&gsmi_dev.lock, flags);

	saved_reason |= (1 << reason);

	/* data pointer */
	memset(gsmi_dev.data_buf->start, 0, gsmi_dev.data_buf->length);
	memcpy(gsmi_dev.data_buf->start, &entry, sizeof(entry));

	/* parameter buffer */
	param.data_ptr = gsmi_dev.data_buf->address;
	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);
	memcpy(gsmi_dev.param_buf->start, &param, sizeof(param));

	rc = gsmi_exec(GSMI_CALLBACK, GSMI_CMD_SET_EVENT_LOG);

	spin_unlock_irqrestore(&gsmi_dev.lock, flags);

	if (rc < 0)
		printk(KERN_ERR "gsmi: Log Shutdown Reason failed\n");
	else
		printk(KERN_EMERG "gsmi: Log Shutdown Reason 0x%02x\n",
		       reason);

	return rc;
}

static int gsmi_reboot_callback(struct notifier_block *nb,
				unsigned long reason, void *arg)
{
	gsmi_shutdown_reason(GSMI_SHUTDOWN_CLEAN);
	return NOTIFY_DONE;
}

static struct notifier_block gsmi_reboot_notifier = {
	.notifier_call = gsmi_reboot_callback
};

static int gsmi_die_callback(struct notifier_block *nb,
			     unsigned long reason, void *arg)
{
	if (reason == DIE_OOPS)
		gsmi_shutdown_reason(GSMI_SHUTDOWN_OOPS);
	return NOTIFY_DONE;
}

static struct notifier_block gsmi_die_notifier = {
	.notifier_call = gsmi_die_callback
};

static int gsmi_panic_callback(struct notifier_block *nb,
			       unsigned long reason, void *arg)
{
	gsmi_shutdown_reason(GSMI_SHUTDOWN_PANIC);
	return NOTIFY_DONE;
}

static struct notifier_block gsmi_panic_notifier = {
	.notifier_call = gsmi_panic_callback,
};

/*
 * This hash function was blatantly copied from include/linux/hash.h.
 * It is used by this driver to obfuscate a board name that requires a
 * quirk within this driver.
 *
 * Please do not remove this copy of the function as any changes to the
 * global utility hash_64() function would break this driver's ability
 * to identify a board and provide the appropriate quirk -- mikew@google.com
 */
static u64 __init local_hash_64(u64 val, unsigned bits)
{
	u64 hash = val;

	/*  Sigh, gcc can't optimise this alone like it does for 32 bits. */
	u64 n = hash;
	n <<= 18;
	hash -= n;
	n <<= 33;
	hash -= n;
	n <<= 3;
	hash += n;
	n <<= 3;
	hash -= n;
	n <<= 4;
	hash += n;
	n <<= 2;
	hash += n;

	/* High bits are more random, so use them. */
	return hash >> (64 - bits);
}

static u32 __init hash_oem_table_id(char s[8])
{
	u64 input;
	memcpy(&input, s, 8);
	return local_hash_64(input, 32);
}

static const struct dmi_system_id gsmi_dmi_table[] __initconst = {
	{
		.ident = "Google Board",
		.matches = {
			DMI_MATCH(DMI_BOARD_VENDOR, "Google, Inc."),
		},
	},
	{
		.ident = "Coreboot Firmware",
		.matches = {
			DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
		},
	},
	{}
};
MODULE_DEVICE_TABLE(dmi, gsmi_dmi_table);

static __init int gsmi_system_valid(void)
{
	u32 hash;

	if (!dmi_check_system(gsmi_dmi_table))
		return -ENODEV;

	/*
	 * Only newer firmware supports the gsmi interface.  All older
	 * firmware that didn't support this interface used to plug the
	 * table name in the first four bytes of the oem_table_id field.
	 * Newer firmware doesn't do that though, so use that as the
	 * discriminant factor.  We have to do this in order to
	 * whitewash our board names out of the public driver.
	 */
	if (!strncmp(acpi_gbl_FADT.header.oem_table_id, "FACP", 4)) {
		printk(KERN_INFO "gsmi: Board is too old\n");
		return -ENODEV;
	}

	/* Disable on board with 1.0 BIOS due to Google bug 2602657 */
	hash = hash_oem_table_id(acpi_gbl_FADT.header.oem_table_id);
	if (hash == QUIRKY_BOARD_HASH) {
		const char *bios_ver = dmi_get_system_info(DMI_BIOS_VERSION);
		if (strncmp(bios_ver, "1.0", 3) == 0) {
			pr_info("gsmi: disabled on this board's BIOS %s\n",
				bios_ver);
			return -ENODEV;
		}
	}

	/* check for valid SMI command port in ACPI FADT */
	if (acpi_gbl_FADT.smi_command == 0) {
		pr_info("gsmi: missing smi_command\n");
		return -ENODEV;
	}

	/* Found */
	return 0;
}

static struct kobject *gsmi_kobj;

static const struct platform_device_info gsmi_dev_info = {
	.name		= "gsmi",
	.id		= -1,
	/* SMI callbacks require 32bit addresses */
	.dma_mask	= DMA_BIT_MASK(32),
};

#ifdef CONFIG_PM
static void gsmi_log_s0ix_info(u8 cmd)
{
	unsigned long flags;

	/*
	 * If platform has not enabled S0ix logging, then no action is
	 * necessary.
	 */
	if (!s0ix_logging_enable)
		return;

	spin_lock_irqsave(&gsmi_dev.lock, flags);

	memset(gsmi_dev.param_buf->start, 0, gsmi_dev.param_buf->length);

	gsmi_exec(GSMI_CALLBACK, cmd);

	spin_unlock_irqrestore(&gsmi_dev.lock, flags);
}

static int gsmi_log_s0ix_suspend(struct device *dev)
{
	/*
	 * If system is not suspending via firmware using the standard ACPI Sx
	 * types, then make a GSMI call to log the suspend info.
	 */
	if (!pm_suspend_via_firmware())
		gsmi_log_s0ix_info(GSMI_CMD_LOG_S0IX_SUSPEND);

	/*
	 * Always return success, since we do not want suspend
	 * to fail just because of logging failure.
	 */
	return 0;
}

static int gsmi_log_s0ix_resume(struct device *dev)
{
	/*
	 * If system did not resume via firmware, then make a GSMI call to log
	 * the resume info and wake source.
	 */
	if (!pm_resume_via_firmware())
		gsmi_log_s0ix_info(GSMI_CMD_LOG_S0IX_RESUME);

	/*
	 * Always return success, since we do not want resume
	 * to fail just because of logging failure.
	 */
	return 0;
}

static const struct dev_pm_ops gsmi_pm_ops = {
	.suspend_noirq = gsmi_log_s0ix_suspend,
	.resume_noirq = gsmi_log_s0ix_resume,
};

static int gsmi_platform_driver_probe(struct platform_device *dev)
{
	return 0;
}

static struct platform_driver gsmi_driver_info = {
	.driver = {
		.name = "gsmi",
		.pm = &gsmi_pm_ops,
	},
	.probe = gsmi_platform_driver_probe,
};
#endif

static __init int gsmi_init(void)
{
	unsigned long flags;
	int ret;

	ret = gsmi_system_valid();
	if (ret)
		return ret;

	gsmi_dev.smi_cmd = acpi_gbl_FADT.smi_command;

#ifdef CONFIG_PM
	ret = platform_driver_register(&gsmi_driver_info);
	if (unlikely(ret)) {
		printk(KERN_ERR "gsmi: unable to register platform driver\n");
		return ret;
	}
#endif

	/* register device */
	gsmi_dev.pdev = platform_device_register_full(&gsmi_dev_info);
	if (IS_ERR(gsmi_dev.pdev)) {
		printk(KERN_ERR "gsmi: unable to register platform device\n");
		return PTR_ERR(gsmi_dev.pdev);
	}

	/* SMI access needs to be serialized */
	spin_lock_init(&gsmi_dev.lock);

	ret = -ENOMEM;
	gsmi_dev.dma_pool = dma_pool_create("gsmi", &gsmi_dev.pdev->dev,
					     GSMI_BUF_SIZE, GSMI_BUF_ALIGN, 0);
	if (!gsmi_dev.dma_pool)
		goto out_err;

	/*
	 * pre-allocate buffers because sometimes we are called when
	 * this is not feasible: oops, panic, die, mce, etc
	 */
	gsmi_dev.name_buf = gsmi_buf_alloc();
	if (!gsmi_dev.name_buf) {
		printk(KERN_ERR "gsmi: failed to allocate name buffer\n");
		goto out_err;
	}

	gsmi_dev.data_buf = gsmi_buf_alloc();
	if (!gsmi_dev.data_buf) {
		printk(KERN_ERR "gsmi: failed to allocate data buffer\n");
		goto out_err;
	}

	gsmi_dev.param_buf = gsmi_buf_alloc();
	if (!gsmi_dev.param_buf) {
		printk(KERN_ERR "gsmi: failed to allocate param buffer\n");
		goto out_err;
	}

	/*
	 * Determine type of handshake used to serialize the SMI
	 * entry. See also gsmi_exec().
	 *
	 * There's a "behavior" present on some chipsets where writing the
	 * SMI trigger register in the southbridge doesn't result in an
	 * immediate SMI. Rather, the processor can execute "a few" more
	 * instructions before the SMI takes effect. To ensure synchronous
	 * behavior, implement a handshake between the kernel driver and the
	 * firmware handler to spin until released. This ioctl determines
	 * the type of handshake.
	 *
	 * NONE: The firmware handler does not implement any
	 * handshake. Either it doesn't need to, or it's legacy firmware
	 * that doesn't know it needs to and never will.
	 *
	 * CF: The firmware handler will clear the CF in the saved
	 * state before returning. The driver may set the CF and test for
	 * it to clear before proceeding.
	 *
	 * SPIN: The firmware handler does not implement any handshake
	 * but the driver should spin for a hundred or so microseconds
	 * to ensure the SMI has triggered.
	 *
	 * Finally, the handler will return -ENOSYS if
	 * GSMI_CMD_HANDSHAKE_TYPE is unimplemented, which implies
	 * HANDSHAKE_NONE.
	 */
	spin_lock_irqsave(&gsmi_dev.lock, flags);
	gsmi_dev.handshake_type = GSMI_HANDSHAKE_SPIN;
	gsmi_dev.handshake_type =
	    gsmi_exec(GSMI_CALLBACK, GSMI_CMD_HANDSHAKE_TYPE);
	if (gsmi_dev.handshake_type == -ENOSYS)
		gsmi_dev.handshake_type = GSMI_HANDSHAKE_NONE;
	spin_unlock_irqrestore(&gsmi_dev.lock, flags);

	/* Remove and clean up gsmi if the handshake could not complete. */
	if (gsmi_dev.handshake_type == -ENXIO) {
		printk(KERN_INFO "gsmi version " DRIVER_VERSION
		       " failed to load\n");
		ret = -ENODEV;
		goto out_err;
	}

	/* Register in the firmware directory */
	ret = -ENOMEM;
	gsmi_kobj = kobject_create_and_add("gsmi", firmware_kobj);
	if (!gsmi_kobj) {
		printk(KERN_INFO "gsmi: Failed to create firmware kobj\n");
		goto out_err;
	}

	/* Setup eventlog access */
	ret = sysfs_create_bin_file(gsmi_kobj, &eventlog_bin_attr);
	if (ret) {
		printk(KERN_INFO "gsmi: Failed to setup eventlog");
		goto out_err;
	}

	/* Other attributes */
	ret = sysfs_create_files(gsmi_kobj, gsmi_attrs);
	if (ret) {
		printk(KERN_INFO "gsmi: Failed to add attrs");
		goto out_remove_bin_file;
	}

#ifdef CONFIG_EFI_VARS
	ret = efivars_register(&efivars, &efivar_ops, gsmi_kobj);
	if (ret) {
		printk(KERN_INFO "gsmi: Failed to register efivars\n");
		sysfs_remove_files(gsmi_kobj, gsmi_attrs);
		goto out_remove_bin_file;
	}
#endif

	register_reboot_notifier(&gsmi_reboot_notifier);
	register_die_notifier(&gsmi_die_notifier);
	atomic_notifier_chain_register(&panic_notifier_list,
				       &gsmi_panic_notifier);

	printk(KERN_INFO "gsmi version " DRIVER_VERSION " loaded\n");

	return 0;

out_remove_bin_file:
	sysfs_remove_bin_file(gsmi_kobj, &eventlog_bin_attr);
out_err:
	kobject_put(gsmi_kobj);
	gsmi_buf_free(gsmi_dev.param_buf);
	gsmi_buf_free(gsmi_dev.data_buf);
	gsmi_buf_free(gsmi_dev.name_buf);
	dma_pool_destroy(gsmi_dev.dma_pool);
	platform_device_unregister(gsmi_dev.pdev);
	pr_info("gsmi: failed to load: %d\n", ret);
	return ret;
}

static void __exit gsmi_exit(void)
{
	unregister_reboot_notifier(&gsmi_reboot_notifier);
	unregister_die_notifier(&gsmi_die_notifier);
	atomic_notifier_chain_unregister(&panic_notifier_list,
					 &gsmi_panic_notifier);
#ifdef CONFIG_EFI_VARS
	efivars_unregister(&efivars);
#endif

	sysfs_remove_files(gsmi_kobj, gsmi_attrs);
	sysfs_remove_bin_file(gsmi_kobj, &eventlog_bin_attr);
	kobject_put(gsmi_kobj);
	gsmi_buf_free(gsmi_dev.param_buf);
	gsmi_buf_free(gsmi_dev.data_buf);
	gsmi_buf_free(gsmi_dev.name_buf);
	dma_pool_destroy(gsmi_dev.dma_pool);
	platform_device_unregister(gsmi_dev.pdev);
}

module_init(gsmi_init);
module_exit(gsmi_exit);

MODULE_AUTHOR("Google, Inc.");
MODULE_LICENSE("GPL");