1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2012 Intel, Inc.
4 * Copyright (C) 2013 Intel, Inc.
5 * Copyright (C) 2014 Linaro Limited
6 * Copyright (C) 2011-2016 Google, Inc.
7 *
8 * This software is licensed under the terms of the GNU General Public
9 * License version 2, as published by the Free Software Foundation, and
10 * may be copied, distributed, and modified under those terms.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 */
18
19 /* This source file contains the implementation of a special device driver
20 * that intends to provide a *very* fast communication channel between the
21 * guest system and the QEMU emulator.
22 *
23 * Usage from the guest is simply the following (error handling simplified):
24 *
25 * int fd = open("/dev/qemu_pipe",O_RDWR);
26 * .... write() or read() through the pipe.
27 *
28 * This driver doesn't deal with the exact protocol used during the session.
29 * It is intended to be as simple as something like:
30 *
31 * // do this _just_ after opening the fd to connect to a specific
32 * // emulator service.
33 * const char* msg = "<pipename>";
34 * if (write(fd, msg, strlen(msg)+1) < 0) {
35 * ... could not connect to <pipename> service
36 * close(fd);
37 * }
38 *
39 * // after this, simply read() and write() to communicate with the
40 * // service. Exact protocol details left as an exercise to the reader.
41 *
42 * This driver is very fast because it doesn't copy any data through
43 * intermediate buffers, since the emulator is capable of translating
44 * guest user addresses into host ones.
45 *
46 * Note that we must however ensure that each user page involved in the
47 * exchange is properly mapped during a transfer.
48 */
49
50 #include <linux/module.h>
51 #include <linux/mod_devicetable.h>
52 #include <linux/interrupt.h>
53 #include <linux/kernel.h>
54 #include <linux/spinlock.h>
55 #include <linux/miscdevice.h>
56 #include <linux/platform_device.h>
57 #include <linux/poll.h>
58 #include <linux/sched.h>
59 #include <linux/bitops.h>
60 #include <linux/slab.h>
61 #include <linux/io.h>
62 #include <linux/dma-mapping.h>
63 #include <linux/mm.h>
64 #include <linux/acpi.h>
65 #include <linux/bug.h>
66 #include "goldfish_pipe_qemu.h"
67
68 /*
69 * Update this when something changes in the driver's behavior so the host
70 * can benefit from knowing it
71 */
72 enum {
73 PIPE_DRIVER_VERSION = 2,
74 PIPE_CURRENT_DEVICE_VERSION = 2
75 };
76
77 enum {
78 MAX_BUFFERS_PER_COMMAND = 336,
79 MAX_SIGNALLED_PIPES = 64,
80 INITIAL_PIPES_CAPACITY = 64
81 };
82
83 struct goldfish_pipe_dev;
84
85 /* A per-pipe command structure, shared with the host */
86 struct goldfish_pipe_command {
87 s32 cmd; /* PipeCmdCode, guest -> host */
88 s32 id; /* pipe id, guest -> host */
89 s32 status; /* command execution status, host -> guest */
90 s32 reserved; /* to pad to 64-bit boundary */
91 union {
92 /* Parameters for PIPE_CMD_{READ,WRITE} */
93 struct {
94 /* number of buffers, guest -> host */
95 u32 buffers_count;
96 /* number of consumed bytes, host -> guest */
97 s32 consumed_size;
98 /* buffer pointers, guest -> host */
99 u64 ptrs[MAX_BUFFERS_PER_COMMAND];
100 /* buffer sizes, guest -> host */
101 u32 sizes[MAX_BUFFERS_PER_COMMAND];
102 } rw_params;
103 };
104 };
105
106 /* A single signalled pipe information */
107 struct signalled_pipe_buffer {
108 u32 id;
109 u32 flags;
110 };
111
112 /* Parameters for the PIPE_CMD_OPEN command */
113 struct open_command_param {
114 u64 command_buffer_ptr;
115 u32 rw_params_max_count;
116 };
117
118 /* Device-level set of buffers shared with the host */
119 struct goldfish_pipe_dev_buffers {
120 struct open_command_param open_command_params;
121 struct signalled_pipe_buffer
122 signalled_pipe_buffers[MAX_SIGNALLED_PIPES];
123 };
124
125 /* This data type models a given pipe instance */
126 struct goldfish_pipe {
127 /* pipe ID - index into goldfish_pipe_dev::pipes array */
128 u32 id;
129
130 /* The wake flags pipe is waiting for
131 * Note: not protected with any lock, uses atomic operations
132 * and barriers to make it thread-safe.
133 */
134 unsigned long flags;
135
136 /* wake flags host have signalled,
137 * - protected by goldfish_pipe_dev::lock
138 */
139 unsigned long signalled_flags;
140
141 /* A pointer to command buffer */
142 struct goldfish_pipe_command *command_buffer;
143
144 /* doubly linked list of signalled pipes, protected by
145 * goldfish_pipe_dev::lock
146 */
147 struct goldfish_pipe *prev_signalled;
148 struct goldfish_pipe *next_signalled;
149
150 /*
151 * A pipe's own lock. Protects the following:
152 * - *command_buffer - makes sure a command can safely write its
153 * parameters to the host and read the results back.
154 */
155 struct mutex lock;
156
157 /* A wake queue for sleeping until host signals an event */
158 wait_queue_head_t wake_queue;
159
160 /* Pointer to the parent goldfish_pipe_dev instance */
161 struct goldfish_pipe_dev *dev;
162
163 /* A buffer of pages, too large to fit into a stack frame */
164 struct page *pages[MAX_BUFFERS_PER_COMMAND];
165 };
166
167 /* The global driver data. Holds a reference to the i/o page used to
168 * communicate with the emulator, and a wake queue for blocked tasks
169 * waiting to be awoken.
170 */
171 struct goldfish_pipe_dev {
172 /* A magic number to check if this is an instance of this struct */
173 void *magic;
174
175 /*
176 * Global device spinlock. Protects the following members:
177 * - pipes, pipes_capacity
178 * - [*pipes, *pipes + pipes_capacity) - array data
179 * - first_signalled_pipe,
180 * goldfish_pipe::prev_signalled,
181 * goldfish_pipe::next_signalled,
182 * goldfish_pipe::signalled_flags - all singnalled-related fields,
183 * in all allocated pipes
184 * - open_command_params - PIPE_CMD_OPEN-related buffers
185 *
186 * It looks like a lot of different fields, but the trick is that
187 * the only operation that happens often is the signalled pipes array
188 * manipulation. That's why it's OK for now to keep the rest of the
189 * fields under the same lock. If we notice too much contention because
190 * of PIPE_CMD_OPEN, then we should add a separate lock there.
191 */
192 spinlock_t lock;
193
194 /*
195 * Array of the pipes of |pipes_capacity| elements,
196 * indexed by goldfish_pipe::id
197 */
198 struct goldfish_pipe **pipes;
199 u32 pipes_capacity;
200
201 /* Pointers to the buffers host uses for interaction with this driver */
202 struct goldfish_pipe_dev_buffers *buffers;
203
204 /* Head of a doubly linked list of signalled pipes */
205 struct goldfish_pipe *first_signalled_pipe;
206
207 /* ptr to platform device's device struct */
208 struct device *pdev_dev;
209
210 /* Some device-specific data */
211 int irq;
212 int version;
213 unsigned char __iomem *base;
214
215 struct miscdevice miscdev;
216 };
217
goldfish_pipe_cmd_locked(struct goldfish_pipe * pipe,enum PipeCmdCode cmd)218 static int goldfish_pipe_cmd_locked(struct goldfish_pipe *pipe,
219 enum PipeCmdCode cmd)
220 {
221 pipe->command_buffer->cmd = cmd;
222 /* failure by default */
223 pipe->command_buffer->status = PIPE_ERROR_INVAL;
224 writel(pipe->id, pipe->dev->base + PIPE_REG_CMD);
225 return pipe->command_buffer->status;
226 }
227
goldfish_pipe_cmd(struct goldfish_pipe * pipe,enum PipeCmdCode cmd)228 static int goldfish_pipe_cmd(struct goldfish_pipe *pipe, enum PipeCmdCode cmd)
229 {
230 int status;
231
232 if (mutex_lock_interruptible(&pipe->lock))
233 return PIPE_ERROR_IO;
234 status = goldfish_pipe_cmd_locked(pipe, cmd);
235 mutex_unlock(&pipe->lock);
236 return status;
237 }
238
239 /*
240 * This function converts an error code returned by the emulator through
241 * the PIPE_REG_STATUS i/o register into a valid negative errno value.
242 */
goldfish_pipe_error_convert(int status)243 static int goldfish_pipe_error_convert(int status)
244 {
245 switch (status) {
246 case PIPE_ERROR_AGAIN:
247 return -EAGAIN;
248 case PIPE_ERROR_NOMEM:
249 return -ENOMEM;
250 case PIPE_ERROR_IO:
251 return -EIO;
252 default:
253 return -EINVAL;
254 }
255 }
256
goldfish_pin_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)257 static int goldfish_pin_pages(unsigned long first_page,
258 unsigned long last_page,
259 unsigned int last_page_size,
260 int is_write,
261 struct page *pages[MAX_BUFFERS_PER_COMMAND],
262 unsigned int *iter_last_page_size)
263 {
264 int ret;
265 int requested_pages = ((last_page - first_page) >> PAGE_SHIFT) + 1;
266
267 if (requested_pages > MAX_BUFFERS_PER_COMMAND) {
268 requested_pages = MAX_BUFFERS_PER_COMMAND;
269 *iter_last_page_size = PAGE_SIZE;
270 } else {
271 *iter_last_page_size = last_page_size;
272 }
273
274 ret = pin_user_pages_fast(first_page, requested_pages,
275 !is_write ? FOLL_WRITE : 0,
276 pages);
277 if (ret <= 0)
278 return -EFAULT;
279 if (ret < requested_pages)
280 *iter_last_page_size = PAGE_SIZE;
281
282 return ret;
283 }
284
285 /* Populate the call parameters, merging adjacent pages together */
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)286 static void populate_rw_params(struct page **pages,
287 int pages_count,
288 unsigned long address,
289 unsigned long address_end,
290 unsigned long first_page,
291 unsigned long last_page,
292 unsigned int iter_last_page_size,
293 int is_write,
294 struct goldfish_pipe_command *command)
295 {
296 /*
297 * Process the first page separately - it's the only page that
298 * needs special handling for its start address.
299 */
300 unsigned long xaddr = page_to_phys(pages[0]);
301 unsigned long xaddr_prev = xaddr;
302 int buffer_idx = 0;
303 int i = 1;
304 int size_on_page = first_page == last_page
305 ? (int)(address_end - address)
306 : (PAGE_SIZE - (address & ~PAGE_MASK));
307 command->rw_params.ptrs[0] = (u64)(xaddr | (address & ~PAGE_MASK));
308 command->rw_params.sizes[0] = size_on_page;
309 for (; i < pages_count; ++i) {
310 xaddr = page_to_phys(pages[i]);
311 size_on_page = (i == pages_count - 1) ?
312 iter_last_page_size : PAGE_SIZE;
313 if (xaddr == xaddr_prev + PAGE_SIZE) {
314 command->rw_params.sizes[buffer_idx] += size_on_page;
315 } else {
316 ++buffer_idx;
317 command->rw_params.ptrs[buffer_idx] = (u64)xaddr;
318 command->rw_params.sizes[buffer_idx] = size_on_page;
319 }
320 xaddr_prev = xaddr;
321 }
322 command->rw_params.buffers_count = buffer_idx + 1;
323 }
324
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)325 static int transfer_max_buffers(struct goldfish_pipe *pipe,
326 unsigned long address,
327 unsigned long address_end,
328 int is_write,
329 unsigned long last_page,
330 unsigned int last_page_size,
331 s32 *consumed_size,
332 int *status)
333 {
334 unsigned long first_page = address & PAGE_MASK;
335 unsigned int iter_last_page_size;
336 int pages_count;
337
338 /* Serialize access to the pipe command buffers */
339 if (mutex_lock_interruptible(&pipe->lock))
340 return -ERESTARTSYS;
341
342 pages_count = goldfish_pin_pages(first_page, last_page,
343 last_page_size, is_write,
344 pipe->pages, &iter_last_page_size);
345 if (pages_count < 0) {
346 mutex_unlock(&pipe->lock);
347 return pages_count;
348 }
349
350 populate_rw_params(pipe->pages, pages_count, address, address_end,
351 first_page, last_page, iter_last_page_size, is_write,
352 pipe->command_buffer);
353
354 /* Transfer the data */
355 *status = goldfish_pipe_cmd_locked(pipe,
356 is_write ? PIPE_CMD_WRITE : PIPE_CMD_READ);
357
358 *consumed_size = pipe->command_buffer->rw_params.consumed_size;
359
360 unpin_user_pages_dirty_lock(pipe->pages, pages_count,
361 !is_write && *consumed_size > 0);
362
363 mutex_unlock(&pipe->lock);
364 return 0;
365 }
366
wait_for_host_signal(struct goldfish_pipe * pipe,int is_write)367 static int wait_for_host_signal(struct goldfish_pipe *pipe, int is_write)
368 {
369 u32 wake_bit = is_write ? BIT_WAKE_ON_WRITE : BIT_WAKE_ON_READ;
370
371 set_bit(wake_bit, &pipe->flags);
372
373 /* Tell the emulator we're going to wait for a wake event */
374 goldfish_pipe_cmd(pipe,
375 is_write ? PIPE_CMD_WAKE_ON_WRITE : PIPE_CMD_WAKE_ON_READ);
376
377 while (test_bit(wake_bit, &pipe->flags)) {
378 if (wait_event_interruptible(pipe->wake_queue,
379 !test_bit(wake_bit, &pipe->flags)))
380 return -ERESTARTSYS;
381
382 if (test_bit(BIT_CLOSED_ON_HOST, &pipe->flags))
383 return -EIO;
384 }
385
386 return 0;
387 }
388
goldfish_pipe_read_write(struct file * filp,char __user * buffer,size_t bufflen,int is_write)389 static ssize_t goldfish_pipe_read_write(struct file *filp,
390 char __user *buffer,
391 size_t bufflen,
392 int is_write)
393 {
394 struct goldfish_pipe *pipe = filp->private_data;
395 int count = 0, ret = -EINVAL;
396 unsigned long address, address_end, last_page;
397 unsigned int last_page_size;
398
399 /* If the emulator already closed the pipe, no need to go further */
400 if (unlikely(test_bit(BIT_CLOSED_ON_HOST, &pipe->flags)))
401 return -EIO;
402 /* Null reads or writes succeeds */
403 if (unlikely(bufflen == 0))
404 return 0;
405 /* Check the buffer range for access */
406 if (unlikely(!access_ok(buffer, bufflen)))
407 return -EFAULT;
408
409 address = (unsigned long)buffer;
410 address_end = address + bufflen;
411 last_page = (address_end - 1) & PAGE_MASK;
412 last_page_size = ((address_end - 1) & ~PAGE_MASK) + 1;
413
414 while (address < address_end) {
415 s32 consumed_size;
416 int status;
417
418 ret = transfer_max_buffers(pipe, address, address_end, is_write,
419 last_page, last_page_size,
420 &consumed_size, &status);
421 if (ret < 0)
422 break;
423
424 if (consumed_size > 0) {
425 /* No matter what's the status, we've transferred
426 * something.
427 */
428 count += consumed_size;
429 address += consumed_size;
430 }
431 if (status > 0)
432 continue;
433 if (status == 0) {
434 /* EOF */
435 ret = 0;
436 break;
437 }
438 if (count > 0) {
439 /*
440 * An error occurred, but we already transferred
441 * something on one of the previous iterations.
442 * Just return what we already copied and log this
443 * err.
444 */
445 if (status != PIPE_ERROR_AGAIN)
446 dev_err_ratelimited(pipe->dev->pdev_dev,
447 "backend error %d on %s\n",
448 status, is_write ? "write" : "read");
449 break;
450 }
451
452 /*
453 * If the error is not PIPE_ERROR_AGAIN, or if we are in
454 * non-blocking mode, just return the error code.
455 */
456 if (status != PIPE_ERROR_AGAIN ||
457 (filp->f_flags & O_NONBLOCK) != 0) {
458 ret = goldfish_pipe_error_convert(status);
459 break;
460 }
461
462 status = wait_for_host_signal(pipe, is_write);
463 if (status < 0)
464 return status;
465 }
466
467 if (count > 0)
468 return count;
469 return ret;
470 }
471
goldfish_pipe_read(struct file * filp,char __user * buffer,size_t bufflen,loff_t * ppos)472 static ssize_t goldfish_pipe_read(struct file *filp, char __user *buffer,
473 size_t bufflen, loff_t *ppos)
474 {
475 return goldfish_pipe_read_write(filp, buffer, bufflen,
476 /* is_write */ 0);
477 }
478
goldfish_pipe_write(struct file * filp,const char __user * buffer,size_t bufflen,loff_t * ppos)479 static ssize_t goldfish_pipe_write(struct file *filp,
480 const char __user *buffer, size_t bufflen,
481 loff_t *ppos)
482 {
483 /* cast away the const */
484 char __user *no_const_buffer = (char __user *)buffer;
485
486 return goldfish_pipe_read_write(filp, no_const_buffer, bufflen,
487 /* is_write */ 1);
488 }
489
goldfish_pipe_poll(struct file * filp,poll_table * wait)490 static __poll_t goldfish_pipe_poll(struct file *filp, poll_table *wait)
491 {
492 struct goldfish_pipe *pipe = filp->private_data;
493 __poll_t mask = 0;
494 int status;
495
496 poll_wait(filp, &pipe->wake_queue, wait);
497
498 status = goldfish_pipe_cmd(pipe, PIPE_CMD_POLL);
499 if (status < 0)
500 return -ERESTARTSYS;
501
502 if (status & PIPE_POLL_IN)
503 mask |= EPOLLIN | EPOLLRDNORM;
504 if (status & PIPE_POLL_OUT)
505 mask |= EPOLLOUT | EPOLLWRNORM;
506 if (status & PIPE_POLL_HUP)
507 mask |= EPOLLHUP;
508 if (test_bit(BIT_CLOSED_ON_HOST, &pipe->flags))
509 mask |= EPOLLERR;
510
511 return mask;
512 }
513
signalled_pipes_add_locked(struct goldfish_pipe_dev * dev,u32 id,u32 flags)514 static void signalled_pipes_add_locked(struct goldfish_pipe_dev *dev,
515 u32 id, u32 flags)
516 {
517 struct goldfish_pipe *pipe;
518
519 if (WARN_ON(id >= dev->pipes_capacity))
520 return;
521
522 pipe = dev->pipes[id];
523 if (!pipe)
524 return;
525 pipe->signalled_flags |= flags;
526
527 if (pipe->prev_signalled || pipe->next_signalled ||
528 dev->first_signalled_pipe == pipe)
529 return; /* already in the list */
530 pipe->next_signalled = dev->first_signalled_pipe;
531 if (dev->first_signalled_pipe)
532 dev->first_signalled_pipe->prev_signalled = pipe;
533 dev->first_signalled_pipe = pipe;
534 }
535
signalled_pipes_remove_locked(struct goldfish_pipe_dev * dev,struct goldfish_pipe * pipe)536 static void signalled_pipes_remove_locked(struct goldfish_pipe_dev *dev,
537 struct goldfish_pipe *pipe)
538 {
539 if (pipe->prev_signalled)
540 pipe->prev_signalled->next_signalled = pipe->next_signalled;
541 if (pipe->next_signalled)
542 pipe->next_signalled->prev_signalled = pipe->prev_signalled;
543 if (pipe == dev->first_signalled_pipe)
544 dev->first_signalled_pipe = pipe->next_signalled;
545 pipe->prev_signalled = NULL;
546 pipe->next_signalled = NULL;
547 }
548
signalled_pipes_pop_front(struct goldfish_pipe_dev * dev,int * wakes)549 static struct goldfish_pipe *signalled_pipes_pop_front(
550 struct goldfish_pipe_dev *dev, int *wakes)
551 {
552 struct goldfish_pipe *pipe;
553 unsigned long flags;
554
555 spin_lock_irqsave(&dev->lock, flags);
556
557 pipe = dev->first_signalled_pipe;
558 if (pipe) {
559 *wakes = pipe->signalled_flags;
560 pipe->signalled_flags = 0;
561 /*
562 * This is an optimized version of
563 * signalled_pipes_remove_locked()
564 * - We want to make it as fast as possible to
565 * wake the sleeping pipe operations faster.
566 */
567 dev->first_signalled_pipe = pipe->next_signalled;
568 if (dev->first_signalled_pipe)
569 dev->first_signalled_pipe->prev_signalled = NULL;
570 pipe->next_signalled = NULL;
571 }
572
573 spin_unlock_irqrestore(&dev->lock, flags);
574 return pipe;
575 }
576
goldfish_interrupt_task(int irq,void * dev_addr)577 static irqreturn_t goldfish_interrupt_task(int irq, void *dev_addr)
578 {
579 /* Iterate over the signalled pipes and wake them one by one */
580 struct goldfish_pipe_dev *dev = dev_addr;
581 struct goldfish_pipe *pipe;
582 int wakes;
583
584 while ((pipe = signalled_pipes_pop_front(dev, &wakes)) != NULL) {
585 if (wakes & PIPE_WAKE_CLOSED) {
586 pipe->flags = 1 << BIT_CLOSED_ON_HOST;
587 } else {
588 if (wakes & PIPE_WAKE_READ)
589 clear_bit(BIT_WAKE_ON_READ, &pipe->flags);
590 if (wakes & PIPE_WAKE_WRITE)
591 clear_bit(BIT_WAKE_ON_WRITE, &pipe->flags);
592 }
593 /*
594 * wake_up_interruptible() implies a write barrier, so don't
595 * explicitly add another one here.
596 */
597 wake_up_interruptible(&pipe->wake_queue);
598 }
599 return IRQ_HANDLED;
600 }
601
602 static void goldfish_pipe_device_deinit(struct platform_device *pdev,
603 struct goldfish_pipe_dev *dev);
604
605 /*
606 * The general idea of the (threaded) interrupt handling:
607 *
608 * 1. device raises an interrupt if there's at least one signalled pipe
609 * 2. IRQ handler reads the signalled pipes and their count from the device
610 * 3. device writes them into a shared buffer and returns the count
611 * it only resets the IRQ if it has returned all signalled pipes,
612 * otherwise it leaves it raised, so IRQ handler will be called
613 * again for the next chunk
614 * 4. IRQ handler adds all returned pipes to the device's signalled pipes list
615 * 5. IRQ handler defers processing the signalled pipes from the list in a
616 * separate context
617 */
goldfish_pipe_interrupt(int irq,void * dev_id)618 static irqreturn_t goldfish_pipe_interrupt(int irq, void *dev_id)
619 {
620 u32 count;
621 u32 i;
622 unsigned long flags;
623 struct goldfish_pipe_dev *dev = dev_id;
624
625 if (dev->magic != &goldfish_pipe_device_deinit)
626 return IRQ_NONE;
627
628 /* Request the signalled pipes from the device */
629 spin_lock_irqsave(&dev->lock, flags);
630
631 count = readl(dev->base + PIPE_REG_GET_SIGNALLED);
632 if (count == 0) {
633 spin_unlock_irqrestore(&dev->lock, flags);
634 return IRQ_NONE;
635 }
636 if (count > MAX_SIGNALLED_PIPES)
637 count = MAX_SIGNALLED_PIPES;
638
639 for (i = 0; i < count; ++i)
640 signalled_pipes_add_locked(dev,
641 dev->buffers->signalled_pipe_buffers[i].id,
642 dev->buffers->signalled_pipe_buffers[i].flags);
643
644 spin_unlock_irqrestore(&dev->lock, flags);
645
646 return IRQ_WAKE_THREAD;
647 }
648
get_free_pipe_id_locked(struct goldfish_pipe_dev * dev)649 static int get_free_pipe_id_locked(struct goldfish_pipe_dev *dev)
650 {
651 int id;
652
653 for (id = 0; id < dev->pipes_capacity; ++id)
654 if (!dev->pipes[id])
655 return id;
656
657 {
658 /* Reallocate the array.
659 * Since get_free_pipe_id_locked runs with interrupts disabled,
660 * we don't want to make calls that could lead to sleep.
661 */
662 u32 new_capacity = 2 * dev->pipes_capacity;
663 struct goldfish_pipe **pipes =
664 kcalloc(new_capacity, sizeof(*pipes), GFP_ATOMIC);
665 if (!pipes)
666 return -ENOMEM;
667 memcpy(pipes, dev->pipes, sizeof(*pipes) * dev->pipes_capacity);
668 kfree(dev->pipes);
669 dev->pipes = pipes;
670 id = dev->pipes_capacity;
671 dev->pipes_capacity = new_capacity;
672 }
673 return id;
674 }
675
676 /* A helper function to get the instance of goldfish_pipe_dev from file */
to_goldfish_pipe_dev(struct file * file)677 static struct goldfish_pipe_dev *to_goldfish_pipe_dev(struct file *file)
678 {
679 struct miscdevice *miscdev = file->private_data;
680
681 return container_of(miscdev, struct goldfish_pipe_dev, miscdev);
682 }
683
684 /**
685 * goldfish_pipe_open - open a channel to the AVD
686 * @inode: inode of device
687 * @file: file struct of opener
688 *
689 * Create a new pipe link between the emulator and the use application.
690 * Each new request produces a new pipe.
691 *
692 * Note: we use the pipe ID as a mux. All goldfish emulations are 32bit
693 * right now so this is fine. A move to 64bit will need this addressing
694 */
goldfish_pipe_open(struct inode * inode,struct file * file)695 static int goldfish_pipe_open(struct inode *inode, struct file *file)
696 {
697 struct goldfish_pipe_dev *dev = to_goldfish_pipe_dev(file);
698 unsigned long flags;
699 int id;
700 int status;
701
702 /* Allocate new pipe kernel object */
703 struct goldfish_pipe *pipe = kzalloc(sizeof(*pipe), GFP_KERNEL);
704
705 if (!pipe)
706 return -ENOMEM;
707
708 pipe->dev = dev;
709 mutex_init(&pipe->lock);
710 init_waitqueue_head(&pipe->wake_queue);
711
712 /*
713 * Command buffer needs to be allocated on its own page to make sure
714 * it is physically contiguous in host's address space.
715 */
716 BUILD_BUG_ON(sizeof(struct goldfish_pipe_command) > PAGE_SIZE);
717 pipe->command_buffer =
718 (struct goldfish_pipe_command *)__get_free_page(GFP_KERNEL);
719 if (!pipe->command_buffer) {
720 status = -ENOMEM;
721 goto err_pipe;
722 }
723
724 spin_lock_irqsave(&dev->lock, flags);
725
726 id = get_free_pipe_id_locked(dev);
727 if (id < 0) {
728 status = id;
729 goto err_id_locked;
730 }
731
732 dev->pipes[id] = pipe;
733 pipe->id = id;
734 pipe->command_buffer->id = id;
735
736 /* Now tell the emulator we're opening a new pipe. */
737 dev->buffers->open_command_params.rw_params_max_count =
738 MAX_BUFFERS_PER_COMMAND;
739 dev->buffers->open_command_params.command_buffer_ptr =
740 (u64)(unsigned long)__pa(pipe->command_buffer);
741 status = goldfish_pipe_cmd_locked(pipe, PIPE_CMD_OPEN);
742 spin_unlock_irqrestore(&dev->lock, flags);
743 if (status < 0)
744 goto err_cmd;
745 /* All is done, save the pipe into the file's private data field */
746 file->private_data = pipe;
747 return 0;
748
749 err_cmd:
750 spin_lock_irqsave(&dev->lock, flags);
751 dev->pipes[id] = NULL;
752 err_id_locked:
753 spin_unlock_irqrestore(&dev->lock, flags);
754 free_page((unsigned long)pipe->command_buffer);
755 err_pipe:
756 kfree(pipe);
757 return status;
758 }
759
goldfish_pipe_release(struct inode * inode,struct file * filp)760 static int goldfish_pipe_release(struct inode *inode, struct file *filp)
761 {
762 unsigned long flags;
763 struct goldfish_pipe *pipe = filp->private_data;
764 struct goldfish_pipe_dev *dev = pipe->dev;
765
766 /* The guest is closing the channel, so tell the emulator right now */
767 goldfish_pipe_cmd(pipe, PIPE_CMD_CLOSE);
768
769 spin_lock_irqsave(&dev->lock, flags);
770 dev->pipes[pipe->id] = NULL;
771 signalled_pipes_remove_locked(dev, pipe);
772 spin_unlock_irqrestore(&dev->lock, flags);
773
774 filp->private_data = NULL;
775 free_page((unsigned long)pipe->command_buffer);
776 kfree(pipe);
777 return 0;
778 }
779
780 static const struct file_operations goldfish_pipe_fops = {
781 .owner = THIS_MODULE,
782 .read = goldfish_pipe_read,
783 .write = goldfish_pipe_write,
784 .poll = goldfish_pipe_poll,
785 .open = goldfish_pipe_open,
786 .release = goldfish_pipe_release,
787 };
788
init_miscdevice(struct miscdevice * miscdev)789 static void init_miscdevice(struct miscdevice *miscdev)
790 {
791 memset(miscdev, 0, sizeof(*miscdev));
792
793 miscdev->minor = MISC_DYNAMIC_MINOR;
794 miscdev->name = "goldfish_pipe";
795 miscdev->fops = &goldfish_pipe_fops;
796 }
797
write_pa_addr(void * addr,void __iomem * portl,void __iomem * porth)798 static void write_pa_addr(void *addr, void __iomem *portl, void __iomem *porth)
799 {
800 const unsigned long paddr = __pa(addr);
801
802 writel(upper_32_bits(paddr), porth);
803 writel(lower_32_bits(paddr), portl);
804 }
805
goldfish_pipe_device_init(struct platform_device * pdev,struct goldfish_pipe_dev * dev)806 static int goldfish_pipe_device_init(struct platform_device *pdev,
807 struct goldfish_pipe_dev *dev)
808 {
809 int err;
810
811 err = devm_request_threaded_irq(&pdev->dev, dev->irq,
812 goldfish_pipe_interrupt,
813 goldfish_interrupt_task,
814 IRQF_SHARED, "goldfish_pipe", dev);
815 if (err) {
816 dev_err(&pdev->dev, "unable to allocate IRQ for v2\n");
817 return err;
818 }
819
820 init_miscdevice(&dev->miscdev);
821 err = misc_register(&dev->miscdev);
822 if (err) {
823 dev_err(&pdev->dev, "unable to register v2 device\n");
824 return err;
825 }
826
827 dev->pdev_dev = &pdev->dev;
828 dev->first_signalled_pipe = NULL;
829 dev->pipes_capacity = INITIAL_PIPES_CAPACITY;
830 dev->pipes = kcalloc(dev->pipes_capacity, sizeof(*dev->pipes),
831 GFP_KERNEL);
832 if (!dev->pipes) {
833 misc_deregister(&dev->miscdev);
834 return -ENOMEM;
835 }
836
837 /*
838 * We're going to pass two buffers, open_command_params and
839 * signalled_pipe_buffers, to the host. This means each of those buffers
840 * needs to be contained in a single physical page. The easiest choice
841 * is to just allocate a page and place the buffers in it.
842 */
843 BUILD_BUG_ON(sizeof(struct goldfish_pipe_dev_buffers) > PAGE_SIZE);
844 dev->buffers = (struct goldfish_pipe_dev_buffers *)
845 __get_free_page(GFP_KERNEL);
846 if (!dev->buffers) {
847 kfree(dev->pipes);
848 misc_deregister(&dev->miscdev);
849 return -ENOMEM;
850 }
851
852 /* Send the buffer addresses to the host */
853 write_pa_addr(&dev->buffers->signalled_pipe_buffers,
854 dev->base + PIPE_REG_SIGNAL_BUFFER,
855 dev->base + PIPE_REG_SIGNAL_BUFFER_HIGH);
856
857 writel(MAX_SIGNALLED_PIPES,
858 dev->base + PIPE_REG_SIGNAL_BUFFER_COUNT);
859
860 write_pa_addr(&dev->buffers->open_command_params,
861 dev->base + PIPE_REG_OPEN_BUFFER,
862 dev->base + PIPE_REG_OPEN_BUFFER_HIGH);
863
864 platform_set_drvdata(pdev, dev);
865 return 0;
866 }
867
goldfish_pipe_device_deinit(struct platform_device * pdev,struct goldfish_pipe_dev * dev)868 static void goldfish_pipe_device_deinit(struct platform_device *pdev,
869 struct goldfish_pipe_dev *dev)
870 {
871 misc_deregister(&dev->miscdev);
872 kfree(dev->pipes);
873 free_page((unsigned long)dev->buffers);
874 }
875
goldfish_pipe_probe(struct platform_device * pdev)876 static int goldfish_pipe_probe(struct platform_device *pdev)
877 {
878 struct resource *r;
879 struct goldfish_pipe_dev *dev;
880
881 dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
882 if (!dev)
883 return -ENOMEM;
884
885 dev->magic = &goldfish_pipe_device_deinit;
886 spin_lock_init(&dev->lock);
887
888 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
889 if (!r || resource_size(r) < PAGE_SIZE) {
890 dev_err(&pdev->dev, "can't allocate i/o page\n");
891 return -EINVAL;
892 }
893 dev->base = devm_ioremap(&pdev->dev, r->start, PAGE_SIZE);
894 if (!dev->base) {
895 dev_err(&pdev->dev, "ioremap failed\n");
896 return -EINVAL;
897 }
898
899 dev->irq = platform_get_irq(pdev, 0);
900 if (dev->irq < 0)
901 return dev->irq;
902
903 /*
904 * Exchange the versions with the host device
905 *
906 * Note: v1 driver used to not report its version, so we write it before
907 * reading device version back: this allows the host implementation to
908 * detect the old driver (if there was no version write before read).
909 */
910 writel(PIPE_DRIVER_VERSION, dev->base + PIPE_REG_VERSION);
911 dev->version = readl(dev->base + PIPE_REG_VERSION);
912 if (WARN_ON(dev->version < PIPE_CURRENT_DEVICE_VERSION))
913 return -EINVAL;
914
915 return goldfish_pipe_device_init(pdev, dev);
916 }
917
goldfish_pipe_remove(struct platform_device * pdev)918 static void goldfish_pipe_remove(struct platform_device *pdev)
919 {
920 struct goldfish_pipe_dev *dev = platform_get_drvdata(pdev);
921
922 goldfish_pipe_device_deinit(pdev, dev);
923 }
924
925 static const struct acpi_device_id goldfish_pipe_acpi_match[] = {
926 { "GFSH0003", 0 },
927 { },
928 };
929 MODULE_DEVICE_TABLE(acpi, goldfish_pipe_acpi_match);
930
931 static const struct of_device_id goldfish_pipe_of_match[] = {
932 { .compatible = "google,android-pipe", },
933 {},
934 };
935 MODULE_DEVICE_TABLE(of, goldfish_pipe_of_match);
936
937 static struct platform_driver goldfish_pipe_driver = {
938 .probe = goldfish_pipe_probe,
939 .remove_new = goldfish_pipe_remove,
940 .driver = {
941 .name = "goldfish_pipe",
942 .of_match_table = goldfish_pipe_of_match,
943 .acpi_match_table = ACPI_PTR(goldfish_pipe_acpi_match),
944 }
945 };
946
947 module_platform_driver(goldfish_pipe_driver);
948 MODULE_AUTHOR("David Turner <digit@google.com>");
949 MODULE_DESCRIPTION("Goldfish virtual device for QEMU pipes");
950 MODULE_LICENSE("GPL v2");
951