aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/platform/goldfish/goldfish_pipe.c
blob: 999f1152655abb9e0154663f698b7e58dc670dfe (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
/*
 * Copyright (C) 2012 Intel, Inc.
 * Copyright (C) 2013 Intel, Inc.
 * Copyright (C) 2014 Linaro Limited
 * Copyright (C) 2011-2016 Google, Inc.
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * 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.
 *
 */

/* This source file contains the implementation of a special device driver
 * that intends to provide a *very* fast communication channel between the
 * guest system and the QEMU emulator.
 *
 * Usage from the guest is simply the following (error handling simplified):
 *
 *    int  fd = open("/dev/qemu_pipe",O_RDWR);
 *    .... write() or read() through the pipe.
 *
 * This driver doesn't deal with the exact protocol used during the session.
 * It is intended to be as simple as something like:
 *
 *    // do this _just_ after opening the fd to connect to a specific
 *    // emulator service.
 *    const char*  msg = "<pipename>";
 *    if (write(fd, msg, strlen(msg)+1) < 0) {
 *       ... could not connect to <pipename> service
 *       close(fd);
 *    }
 *
 *    // after this, simply read() and write() to communicate with the
 *    // service. Exact protocol details left as an exercise to the reader.
 *
 * This driver is very fast because it doesn't copy any data through
 * intermediate buffers, since the emulator is capable of translating
 * guest user addresses into host ones.
 *
 * Note that we must however ensure that each user page involved in the
 * exchange is properly mapped during a transfer.
 */


#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/miscdevice.h>
#include <linux/platform_device.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/bitops.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/goldfish.h>
#include <linux/dma-mapping.h>
#include <linux/mm.h>
#include <linux/acpi.h>

/*
 * Update this when something changes in the driver's behavior so the host
 * can benefit from knowing it
 */
enum {
	PIPE_DRIVER_VERSION = 2,
	PIPE_CURRENT_DEVICE_VERSION = 2
};

/*
 * IMPORTANT: The following constants must match the ones used and defined
 * in external/qemu/hw/goldfish_pipe.c in the Android source tree.
 */

/* List of bitflags returned in status of CMD_POLL command */
enum PipePollFlags {
	PIPE_POLL_IN	= 1 << 0,
	PIPE_POLL_OUT	= 1 << 1,
	PIPE_POLL_HUP	= 1 << 2
};

/* Possible status values used to signal errors - see goldfish_pipe_error_convert */
enum PipeErrors {
	PIPE_ERROR_INVAL  = -1,
	PIPE_ERROR_AGAIN  = -2,
	PIPE_ERROR_NOMEM  = -3,
	PIPE_ERROR_IO     = -4
};

/* Bit-flags used to signal events from the emulator */
enum PipeWakeFlags {
	PIPE_WAKE_CLOSED = 1 << 0,  /* emulator closed pipe */
	PIPE_WAKE_READ   = 1 << 1,  /* pipe can now be read from */
	PIPE_WAKE_WRITE  = 1 << 2  /* pipe can now be written to */
};

/* Bit flags for the 'flags' field */
enum PipeFlagsBits {
	BIT_CLOSED_ON_HOST = 0,  /* pipe closed by host */
	BIT_WAKE_ON_WRITE  = 1,  /* want to be woken on writes */
	BIT_WAKE_ON_READ   = 2,  /* want to be woken on reads */
};

enum PipeRegs {
	PIPE_REG_CMD = 0,

	PIPE_REG_SIGNAL_BUFFER_HIGH = 4,
	PIPE_REG_SIGNAL_BUFFER = 8,
	PIPE_REG_SIGNAL_BUFFER_COUNT = 12,

	PIPE_REG_OPEN_BUFFER_HIGH = 20,
	PIPE_REG_OPEN_BUFFER = 24,

	PIPE_REG_VERSION = 36,

	PIPE_REG_GET_SIGNALLED = 48,
};

enum PipeCmdCode {
	PIPE_CMD_OPEN = 1,	/* to be used by the pipe device itself */
	PIPE_CMD_CLOSE,
	PIPE_CMD_POLL,
	PIPE_CMD_WRITE,
	PIPE_CMD_WAKE_ON_WRITE,
	PIPE_CMD_READ,
	PIPE_CMD_WAKE_ON_READ,

	/*
	 * TODO(zyy): implement a deferred read/write execution to allow
	 * parallel processing of pipe operations on the host.
	 */
	PIPE_CMD_WAKE_ON_DONE_IO,
};

enum {
	MAX_BUFFERS_PER_COMMAND = 336,
	MAX_SIGNALLED_PIPES = 64,
	INITIAL_PIPES_CAPACITY = 64
};

struct goldfish_pipe_dev;
struct goldfish_pipe;
struct goldfish_pipe_command;

/* A per-pipe command structure, shared with the host */
struct goldfish_pipe_command {
	s32 cmd;		/* PipeCmdCode, guest -> host */
	s32 id;			/* pipe id, guest -> host */
	s32 status;		/* command execution status, host -> guest */
	s32 reserved;	/* to pad to 64-bit boundary */
	union {
		/* Parameters for PIPE_CMD_{READ,WRITE} */
		struct {
			/* number of buffers, guest -> host */
			u32 buffers_count;
			/* number of consumed bytes, host -> guest */
			s32 consumed_size;
			/* buffer pointers, guest -> host */
			u64 ptrs[MAX_BUFFERS_PER_COMMAND];
			/* buffer sizes, guest -> host */
			u32 sizes[MAX_BUFFERS_PER_COMMAND];
		} rw_params;
	};
};

/* A single signalled pipe information */
struct signalled_pipe_buffer {
	u32 id;
	u32 flags;
};

/* Parameters for the PIPE_CMD_OPEN command */
struct open_command_param {
	u64 command_buffer_ptr;
	u32 rw_params_max_count;
};

/* Device-level set of buffers shared with the host */
struct goldfish_pipe_dev_buffers {
	struct open_command_param open_command_params;
	struct signalled_pipe_buffer signalled_pipe_buffers[
		MAX_SIGNALLED_PIPES];
};

/* This data type models a given pipe instance */
struct goldfish_pipe {
	/* pipe ID - index into goldfish_pipe_dev::pipes array */
	u32 id;
	/* The wake flags pipe is waiting for
	 * Note: not protected with any lock, uses atomic operations
	 *  and barriers to make it thread-safe.
	 */
	unsigned long flags;
	/* wake flags host have signalled,
	 *  - protected by goldfish_pipe_dev::lock
	 */
	unsigned long signalled_flags;

	/* A pointer to command buffer */
	struct goldfish_pipe_command *command_buffer;

	/* doubly linked list of signalled pipes, protected by
	 * goldfish_pipe_dev::lock
	 */
	struct goldfish_pipe *prev_signalled;
	struct goldfish_pipe *next_signalled;

	/*
	 * A pipe's own lock. Protects the following:
	 *  - *command_buffer - makes sure a command can safely write its
	 *    parameters to the host and read the results back.
	 */
	struct mutex lock;

	/* A wake queue for sleeping until host signals an event */
	wait_queue_head_t wake_queue;
	/* Pointer to the parent goldfish_pipe_dev instance */
	struct goldfish_pipe_dev *dev;
};

/* The global driver data. Holds a reference to the i/o page used to
 * communicate with the emulator, and a wake queue for blocked tasks
 * waiting to be awoken.
 */
struct goldfish_pipe_dev {
	/*
	 * Global device spinlock. Protects the following members:
	 *  - pipes, pipes_capacity
	 *  - [*pipes, *pipes + pipes_capacity) - array data
	 *  - first_signalled_pipe,
	 *      goldfish_pipe::prev_signalled,
	 *      goldfish_pipe::next_signalled,
	 *      goldfish_pipe::signalled_flags - all singnalled-related fields,
	 *                                       in all allocated pipes
	 *  - open_command_params - PIPE_CMD_OPEN-related buffers
	 *
	 * It looks like a lot of different fields, but the trick is that
	 * the only operation that happens often is the signalled pipes array
	 * manipulation. That's why it's OK for now to keep the rest of the
	 * fields under the same lock. If we notice too much contention because
	 * of PIPE_CMD_OPEN, then we should add a separate lock there.
	 */
	spinlock_t lock;

	/*
	 * Array of the pipes of |pipes_capacity| elements,
	 * indexed by goldfish_pipe::id
	 */
	struct goldfish_pipe **pipes;
	u32 pipes_capacity;

	/* Pointers to the buffers host uses for interaction with this driver */
	struct goldfish_pipe_dev_buffers *buffers;

	/* Head of a doubly linked list of signalled pipes */
	struct goldfish_pipe *first_signalled_pipe;

	/* Some device-specific data */
	int irq;
	int version;
	unsigned char __iomem *base;
};

static struct goldfish_pipe_dev pipe_dev[1] = {};

static int goldfish_cmd_locked(struct goldfish_pipe *pipe, enum PipeCmdCode cmd)
{
	pipe->command_buffer->cmd = cmd;
	/* failure by default */
	pipe->command_buffer->status = PIPE_ERROR_INVAL;
	writel(pipe->id, pipe->dev->base + PIPE_REG_CMD);
	return pipe->command_buffer->status;
}

static int goldfish_cmd(struct goldfish_pipe *pipe, enum PipeCmdCode cmd)
{
	int status;

	if (mutex_lock_interruptible(&pipe->lock))
		return PIPE_ERROR_IO;
	status = goldfish_cmd_locked(pipe, cmd);
	mutex_unlock(&pipe->lock);
	return status;
}

/*
 * This function converts an error code returned by the emulator through
 * the PIPE_REG_STATUS i/o register into a valid negative errno value.
 */
static int goldfish_pipe_error_convert(int status)
{
	switch (status) {
	case PIPE_ERROR_AGAIN:
		return -EAGAIN;
	case PIPE_ERROR_NOMEM:
		return -ENOMEM;
	case PIPE_ERROR_IO:
		return -EIO;
	default:
		return -EINVAL;
	}
}

static int pin_user_pages(unsigned long first_page, unsigned long last_page,
	unsigned int last_page_size, int is_write,
	struct page *pages[MAX_BUFFERS_PER_COMMAND],
	unsigned int *iter_last_page_size)
{
	int ret;
	int requested_pages = ((last_page - first_page) >> PAGE_SHIFT) + 1;

	if (requested_pages > MAX_BUFFERS_PER_COMMAND) {
		requested_pages = MAX_BUFFERS_PER_COMMAND;
		*iter_last_page_size = PAGE_SIZE;
	} else {
		*iter_last_page_size = last_page_size;
	}

	ret = get_user_pages_fast(
			first_page, requested_pages, !is_write, pages);
	if (ret <= 0)
		return -EFAULT;
	if (ret < requested_pages)
		*iter_last_page_size = PAGE_SIZE;
	return ret;

}

static void release_user_pages(struct page **pages, int pages_count,
	int is_write, s32 consumed_size)
{
	int i;

	for (i = 0; i < pages_count; i++) {
		if (!is_write && consumed_size > 0)
			set_page_dirty(pages[i]);
		put_page(pages[i]);
	}
}

/* Populate the call parameters, merging adjacent pages together */
static void populate_rw_params(
	struct page **pages, int pages_count,
	unsigned long address, unsigned long address_end,
	unsigned long first_page, unsigned long last_page,
	unsigned int iter_last_page_size, int is_write,
	struct goldfish_pipe_command *command)
{
	/*
	 * Process the first page separately - it's the only page that
	 * needs special handling for its start address.
	 */
	unsigned long xaddr = page_to_phys(pages[0]);
	unsigned long xaddr_prev = xaddr;
	int buffer_idx = 0;
	int i = 1;
	int size_on_page = first_page == last_page
			? (int)(address_end - address)
			: (PAGE_SIZE - (address & ~PAGE_MASK));
	command->rw_params.ptrs[0] = (u64)(xaddr | (address & ~PAGE_MASK));
	command->rw_params.sizes[0] = size_on_page;
	for (; i < pages_count; ++i) {
		xaddr = page_to_phys(pages[i]);
		size_on_page = (i == pages_count - 1) ?
			iter_last_page_size : PAGE_SIZE;
		if (xaddr == xaddr_prev + PAGE_SIZE) {
			command->rw_params.sizes[buffer_idx] += size_on_page;
		} else {
			++buffer_idx;
			command->rw_params.ptrs[buffer_idx] = (u64)xaddr;
			command->rw_params.sizes[buffer_idx] = size_on_page;
		}
		xaddr_prev = xaddr;
	}
	command->rw_params.buffers_count = buffer_idx + 1;
}

static int transfer_max_buffers(struct goldfish_pipe *pipe,
	unsigned long address, unsigned long address_end, int is_write,
	unsigned long last_page, unsigned int last_page_size,
	s32 *consumed_size, int *status)
{
	static struct page *pages[MAX_BUFFERS_PER_COMMAND];
	unsigned long first_page = address & PAGE_MASK;
	unsigned int iter_last_page_size;
	int pages_count = pin_user_pages(first_page, last_page,
			last_page_size, is_write,
			pages, &iter_last_page_size);

	if (pages_count < 0)
		return pages_count;

	/* Serialize access to the pipe command buffers */
	if (mutex_lock_interruptible(&pipe->lock))
		return -ERESTARTSYS;

	populate_rw_params(pages, pages_count, address, address_end,
		first_page, last_page, iter_last_page_size, is_write,
		pipe->command_buffer);

	/* Transfer the data */
	*status = goldfish_cmd_locked(pipe,
				is_write ? PIPE_CMD_WRITE : PIPE_CMD_READ);

	*consumed_size = pipe->command_buffer->rw_params.consumed_size;

	release_user_pages(pages, pages_count, is_write, *consumed_size);

	mutex_unlock(&pipe->lock);

	return 0;
}

static int wait_for_host_signal(struct goldfish_pipe *pipe, int is_write)
{
	u32 wakeBit = is_write ? BIT_WAKE_ON_WRITE : BIT_WAKE_ON_READ;

	set_bit(wakeBit, &pipe->flags);

	/* Tell the emulator we're going to wait for a wake event */
	(void)goldfish_cmd(pipe,
		is_write ? PIPE_CMD_WAKE_ON_WRITE : PIPE_CMD_WAKE_ON_READ);

	while (test_bit(wakeBit, &pipe->flags)) {
		if (wait_event_interruptible(
				pipe->wake_queue,
				!test_bit(wakeBit, &pipe->flags)))
			return -ERESTARTSYS;

		if (test_bit(BIT_CLOSED_ON_HOST, &pipe->flags))
			return -EIO;
	}

	return 0;
}

static ssize_t goldfish_pipe_read_write(struct file *filp,
	char __user *buffer, size_t bufflen, int is_write)
{
	struct goldfish_pipe *pipe = filp->private_data;
	int count = 0, ret = -EINVAL;
	unsigned long address, address_end, last_page;
	unsigned int last_page_size;

	/* If the emulator already closed the pipe, no need to go further */
	if (unlikely(test_bit(BIT_CLOSED_ON_HOST, &pipe->flags)))
		return -EIO;
	/* Null reads or writes succeeds */
	if (unlikely(bufflen == 0))
		return 0;
	/* Check the buffer range for access */
	if (unlikely(!access_ok(is_write ? VERIFY_WRITE : VERIFY_READ,
			buffer, bufflen)))
		return -EFAULT;

	address = (unsigned long)buffer;
	address_end = address + bufflen;
	last_page = (address_end - 1) & PAGE_MASK;
	last_page_size = ((address_end - 1) & ~PAGE_MASK) + 1;

	while (address < address_end) {
		s32 consumed_size;
		int status;

		ret = transfer_max_buffers(pipe, address, address_end, is_write,
				last_page, last_page_size, &consumed_size,
				&status);
		if (ret < 0)
			break;

		if (consumed_size > 0) {
			/* No matter what's the status, we've transferred
			 * something.
			 */
			count += consumed_size;
			address += consumed_size;
		}
		if (status > 0)
			continue;
		if (status == 0) {
			/* EOF */
			ret = 0;
			break;
		}
		if (count > 0) {
			/*
			 * An error occurred, but we already transferred
			 * something on one of the previous iterations.
			 * Just return what we already copied and log this
			 * err.
			 */
			if (status != PIPE_ERROR_AGAIN)
				pr_info_ratelimited("goldfish_pipe: backend error %d on %s\n",
					status, is_write ? "write" : "read");
			break;
		}

		/*
		 * If the error is not PIPE_ERROR_AGAIN, or if we are in
		 * non-blocking mode, just return the error code.
		 */
		if (status != PIPE_ERROR_AGAIN ||
			(filp->f_flags & O_NONBLOCK) != 0) {
			ret = goldfish_pipe_error_convert(status);
			break;
		}

		status = wait_for_host_signal(pipe, is_write);
		if (status < 0)
			return status;
	}

	if (count > 0)
		return count;
	return ret;
}

static ssize_t goldfish_pipe_read(struct file *filp, char __user *buffer,
				size_t bufflen, loff_t *ppos)
{
	return goldfish_pipe_read_write(filp, buffer, bufflen,
			/* is_write */ 0);
}

static ssize_t goldfish_pipe_write(struct file *filp,
				const char __user *buffer, size_t bufflen,
				loff_t *ppos)
{
	return goldfish_pipe_read_write(filp,
			/* cast away the const */(char __user *)buffer, bufflen,
			/* is_write */ 1);
}

static __poll_t goldfish_pipe_poll(struct file *filp, poll_table *wait)
{
	struct goldfish_pipe *pipe = filp->private_data;
	__poll_t mask = 0;
	int status;

	poll_wait(filp, &pipe->wake_queue, wait);

	status = goldfish_cmd(pipe, PIPE_CMD_POLL);
	if (status < 0)
		return -ERESTARTSYS;

	if (status & PIPE_POLL_IN)
		mask |= POLLIN | POLLRDNORM;
	if (status & PIPE_POLL_OUT)
		mask |= POLLOUT | POLLWRNORM;
	if (status & PIPE_POLL_HUP)
		mask |= POLLHUP;
	if (test_bit(BIT_CLOSED_ON_HOST, &pipe->flags))
		mask |= POLLERR;

	return mask;
}

static void signalled_pipes_add_locked(struct goldfish_pipe_dev *dev,
	u32 id, u32 flags)
{
	struct goldfish_pipe *pipe;

	if (WARN_ON(id >= dev->pipes_capacity))
		return;

	pipe = dev->pipes[id];
	if (!pipe)
		return;
	pipe->signalled_flags |= flags;

	if (pipe->prev_signalled || pipe->next_signalled
		|| dev->first_signalled_pipe == pipe)
		return;	/* already in the list */
	pipe->next_signalled = dev->first_signalled_pipe;
	if (dev->first_signalled_pipe)
		dev->first_signalled_pipe->prev_signalled = pipe;
	dev->first_signalled_pipe = pipe;
}

static void signalled_pipes_remove_locked(struct goldfish_pipe_dev *dev,
	struct goldfish_pipe *pipe) {
	if (pipe->prev_signalled)
		pipe->prev_signalled->next_signalled = pipe->next_signalled;
	if (pipe->next_signalled)
		pipe->next_signalled->prev_signalled = pipe->prev_signalled;
	if (pipe == dev->first_signalled_pipe)
		dev->first_signalled_pipe = pipe->next_signalled;
	pipe->prev_signalled = NULL;
	pipe->next_signalled = NULL;
}

static struct goldfish_pipe *signalled_pipes_pop_front(
		struct goldfish_pipe_dev *dev, int *wakes)
{
	struct goldfish_pipe *pipe;
	unsigned long flags;

	spin_lock_irqsave(&dev->lock, flags);

	pipe = dev->first_signalled_pipe;
	if (pipe) {
		*wakes = pipe->signalled_flags;
		pipe->signalled_flags = 0;
		/*
		 * This is an optimized version of
		 * signalled_pipes_remove_locked()
		 * - We want to make it as fast as possible to
		 * wake the sleeping pipe operations faster.
		 */
		dev->first_signalled_pipe = pipe->next_signalled;
		if (dev->first_signalled_pipe)
			dev->first_signalled_pipe->prev_signalled = NULL;
		pipe->next_signalled = NULL;
	}

	spin_unlock_irqrestore(&dev->lock, flags);
	return pipe;
}

static void goldfish_interrupt_task(unsigned long unused)
{
	struct goldfish_pipe_dev *dev = pipe_dev;
	/* Iterate over the signalled pipes and wake them one by one */
	struct goldfish_pipe *pipe;
	int wakes;

	while ((pipe = signalled_pipes_pop_front(dev, &wakes)) != NULL) {
		if (wakes & PIPE_WAKE_CLOSED) {
			pipe->flags = 1 << BIT_CLOSED_ON_HOST;
		} else {
			if (wakes & PIPE_WAKE_READ)
				clear_bit(BIT_WAKE_ON_READ, &pipe->flags);
			if (wakes & PIPE_WAKE_WRITE)
				clear_bit(BIT_WAKE_ON_WRITE, &pipe->flags);
		}
		/*
		 * wake_up_interruptible() implies a write barrier, so don't
		 * explicitly add another one here.
		 */
		wake_up_interruptible(&pipe->wake_queue);
	}
}
DECLARE_TASKLET(goldfish_interrupt_tasklet, goldfish_interrupt_task, 0);

/*
 * The general idea of the interrupt handling:
 *
 *  1. device raises an interrupt if there's at least one signalled pipe
 *  2. IRQ handler reads the signalled pipes and their count from the device
 *  3. device writes them into a shared buffer and returns the count
 *      it only resets the IRQ if it has returned all signalled pipes,
 *      otherwise it leaves it raised, so IRQ handler will be called
 *      again for the next chunk
 *  4. IRQ handler adds all returned pipes to the device's signalled pipes list
 *  5. IRQ handler launches a tasklet to process the signalled pipes from the
 *      list in a separate context
 */
static irqreturn_t goldfish_pipe_interrupt(int irq, void *dev_id)
{
	u32 count;
	u32 i;
	unsigned long flags;
	struct goldfish_pipe_dev *dev = dev_id;

	if (dev != pipe_dev)
		return IRQ_NONE;

	/* Request the signalled pipes from the device */
	spin_lock_irqsave(&dev->lock, flags);

	count = readl(dev->base + PIPE_REG_GET_SIGNALLED);
	if (count == 0) {
		spin_unlock_irqrestore(&dev->lock, flags);
		return IRQ_NONE;
	}
	if (count > MAX_SIGNALLED_PIPES)
		count = MAX_SIGNALLED_PIPES;

	for (i = 0; i < count; ++i)
		signalled_pipes_add_locked(dev,
			dev->buffers->signalled_pipe_buffers[i].id,
			dev->buffers->signalled_pipe_buffers[i].flags);

	spin_unlock_irqrestore(&dev->lock, flags);

	tasklet_schedule(&goldfish_interrupt_tasklet);
	return IRQ_HANDLED;
}

static int get_free_pipe_id_locked(struct goldfish_pipe_dev *dev)
{
	int id;

	for (id = 0; id < dev->pipes_capacity; ++id)
		if (!dev->pipes[id])
			return id;

	{
		/* Reallocate the array */
		u32 new_capacity = 2 * dev->pipes_capacity;
		struct goldfish_pipe **pipes =
			kcalloc(new_capacity, sizeof(*pipes), GFP_ATOMIC);
		if (!pipes)
			return -ENOMEM;
		memcpy(pipes, dev->pipes, sizeof(*pipes) * dev->pipes_capacity);
		kfree(dev->pipes);
		dev->pipes = pipes;
		id = dev->pipes_capacity;
		dev->pipes_capacity = new_capacity;
	}
	return id;
}

/**
 *	goldfish_pipe_open - open a channel to the AVD
 *	@inode: inode of device
 *	@file: file struct of opener
 *
 *	Create a new pipe link between the emulator and the use application.
 *	Each new request produces a new pipe.
 *
 *	Note: we use the pipe ID as a mux. All goldfish emulations are 32bit
 *	right now so this is fine. A move to 64bit will need this addressing
 */
static int goldfish_pipe_open(struct inode *inode, struct file *file)
{
	struct goldfish_pipe_dev *dev = pipe_dev;
	unsigned long flags;
	int id;
	int status;

	/* Allocate new pipe kernel object */
	struct goldfish_pipe *pipe = kzalloc(sizeof(*pipe), GFP_KERNEL);
	if (pipe == NULL)
		return -ENOMEM;

	pipe->dev = dev;
	mutex_init(&pipe->lock);
	init_waitqueue_head(&pipe->wake_queue);

	/*
	 * Command buffer needs to be allocated on its own page to make sure
	 * it is physically contiguous in host's address space.
	 */
	pipe->command_buffer =
		(struct goldfish_pipe_command *)__get_free_page(GFP_KERNEL);
	if (!pipe->command_buffer) {
		status = -ENOMEM;
		goto err_pipe;
	}

	spin_lock_irqsave(&dev->lock, flags);

	id = get_free_pipe_id_locked(dev);
	if (id < 0) {
		status = id;
		goto err_id_locked;
	}

	dev->pipes[id] = pipe;
	pipe->id = id;
	pipe->command_buffer->id = id;

	/* Now tell the emulator we're opening a new pipe. */
	dev->buffers->open_command_params.rw_params_max_count =
			MAX_BUFFERS_PER_COMMAND;
	dev->buffers->open_command_params.command_buffer_ptr =
			(u64)(unsigned long)__pa(pipe->command_buffer);
	status = goldfish_cmd_locked(pipe, PIPE_CMD_OPEN);
	spin_unlock_irqrestore(&dev->lock, flags);
	if (status < 0)
		goto err_cmd;
	/* All is done, save the pipe into the file's private data field */
	file->private_data = pipe;
	return 0;

err_cmd:
	spin_lock_irqsave(&dev->lock, flags);
	dev->pipes[id] = NULL;
err_id_locked:
	spin_unlock_irqrestore(&dev->lock, flags);
	free_page((unsigned long)pipe->command_buffer);
err_pipe:
	kfree(pipe);
	return status;
}

static int goldfish_pipe_release(struct inode *inode, struct file *filp)
{
	unsigned long flags;
	struct goldfish_pipe *pipe = filp->private_data;
	struct goldfish_pipe_dev *dev = pipe->dev;

	/* The guest is closing the channel, so tell the emulator right now */
	(void)goldfish_cmd(pipe, PIPE_CMD_CLOSE);

	spin_lock_irqsave(&dev->lock, flags);
	dev->pipes[pipe->id] = NULL;
	signalled_pipes_remove_locked(dev, pipe);
	spin_unlock_irqrestore(&dev->lock, flags);

	filp->private_data = NULL;
	free_page((unsigned long)pipe->command_buffer);
	kfree(pipe);
	return 0;
}

static const struct file_operations goldfish_pipe_fops = {
	.owner = THIS_MODULE,
	.read = goldfish_pipe_read,
	.write = goldfish_pipe_write,
	.poll = goldfish_pipe_poll,
	.open = goldfish_pipe_open,
	.release = goldfish_pipe_release,
};

static struct miscdevice goldfish_pipe_dev = {
	.minor = MISC_DYNAMIC_MINOR,
	.name = "goldfish_pipe",
	.fops = &goldfish_pipe_fops,
};

static int goldfish_pipe_device_init(struct platform_device *pdev)
{
	char *page;
	struct goldfish_pipe_dev *dev = pipe_dev;
	int err = devm_request_irq(&pdev->dev, dev->irq,
				goldfish_pipe_interrupt,
				IRQF_SHARED, "goldfish_pipe", dev);
	if (err) {
		dev_err(&pdev->dev, "unable to allocate IRQ for v2\n");
		return err;
	}

	err = misc_register(&goldfish_pipe_dev);
	if (err) {
		dev_err(&pdev->dev, "unable to register v2 device\n");
		return err;
	}

	dev->first_signalled_pipe = NULL;
	dev->pipes_capacity = INITIAL_PIPES_CAPACITY;
	dev->pipes = kcalloc(dev->pipes_capacity, sizeof(*dev->pipes),
					GFP_KERNEL);
	if (!dev->pipes)
		return -ENOMEM;

	/*
	 * We're going to pass two buffers, open_command_params and
	 * signalled_pipe_buffers, to the host. This means each of those buffers
	 * needs to be contained in a single physical page. The easiest choice
	 * is to just allocate a page and place the buffers in it.
	 */
	if (WARN_ON(sizeof(*dev->buffers) > PAGE_SIZE))
		return -ENOMEM;

	page = (char *)__get_free_page(GFP_KERNEL);
	if (!page) {
		kfree(dev->pipes);
		return -ENOMEM;
	}
	dev->buffers = (struct goldfish_pipe_dev_buffers *)page;

	/* Send the buffer addresses to the host */
	{
		u64 paddr = __pa(&dev->buffers->signalled_pipe_buffers);

		writel((u32)(unsigned long)(paddr >> 32),
			dev->base + PIPE_REG_SIGNAL_BUFFER_HIGH);
		writel((u32)(unsigned long)paddr,
			dev->base + PIPE_REG_SIGNAL_BUFFER);
		writel((u32)MAX_SIGNALLED_PIPES,
			dev->base + PIPE_REG_SIGNAL_BUFFER_COUNT);

		paddr = __pa(&dev->buffers->open_command_params);
		writel((u32)(unsigned long)(paddr >> 32),
			dev->base + PIPE_REG_OPEN_BUFFER_HIGH);
		writel((u32)(unsigned long)paddr,
			dev->base + PIPE_REG_OPEN_BUFFER);
	}
	return 0;
}

static void goldfish_pipe_device_deinit(struct platform_device *pdev)
{
	struct goldfish_pipe_dev *dev = pipe_dev;

	misc_deregister(&goldfish_pipe_dev);
	kfree(dev->pipes);
	free_page((unsigned long)dev->buffers);
}

static int goldfish_pipe_probe(struct platform_device *pdev)
{
	int err;
	struct resource *r;
	struct goldfish_pipe_dev *dev = pipe_dev;

	if (WARN_ON(sizeof(struct goldfish_pipe_command) > PAGE_SIZE))
		return -ENOMEM;

	/* not thread safe, but this should not happen */
	WARN_ON(dev->base != NULL);

	spin_lock_init(&dev->lock);

	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (r == NULL || resource_size(r) < PAGE_SIZE) {
		dev_err(&pdev->dev, "can't allocate i/o page\n");
		return -EINVAL;
	}
	dev->base = devm_ioremap(&pdev->dev, r->start, PAGE_SIZE);
	if (dev->base == NULL) {
		dev_err(&pdev->dev, "ioremap failed\n");
		return -EINVAL;
	}

	r = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
	if (r == NULL) {
		err = -EINVAL;
		goto error;
	}
	dev->irq = r->start;

	/*
	 * Exchange the versions with the host device
	 *
	 * Note: v1 driver used to not report its version, so we write it before
	 *  reading device version back: this allows the host implementation to
	 *  detect the old driver (if there was no version write before read).
	 */
	writel((u32)PIPE_DRIVER_VERSION, dev->base + PIPE_REG_VERSION);
	dev->version = readl(dev->base + PIPE_REG_VERSION);
	if (WARN_ON(dev->version < PIPE_CURRENT_DEVICE_VERSION))
		return -EINVAL;

	err = goldfish_pipe_device_init(pdev);
	if (!err)
		return 0;

error:
	dev->base = NULL;
	return err;
}

static int goldfish_pipe_remove(struct platform_device *pdev)
{
	struct goldfish_pipe_dev *dev = pipe_dev;
	goldfish_pipe_device_deinit(pdev);
	dev->base = NULL;
	return 0;
}

static const struct acpi_device_id goldfish_pipe_acpi_match[] = {
	{ "GFSH0003", 0 },
	{ },
};
MODULE_DEVICE_TABLE(acpi, goldfish_pipe_acpi_match);

static const struct of_device_id goldfish_pipe_of_match[] = {
	{ .compatible = "google,android-pipe", },
	{},
};
MODULE_DEVICE_TABLE(of, goldfish_pipe_of_match);

static struct platform_driver goldfish_pipe_driver = {
	.probe = goldfish_pipe_probe,
	.remove = goldfish_pipe_remove,
	.driver = {
		.name = "goldfish_pipe",
		.of_match_table = goldfish_pipe_of_match,
		.acpi_match_table = ACPI_PTR(goldfish_pipe_acpi_match),
	}
};

module_platform_driver(goldfish_pipe_driver);
MODULE_AUTHOR("David Turner <digit@google.com>");
MODULE_LICENSE("GPL");

Privacy Policy