Merge tag 'platform-drivers-x86-v4.20-1' of git://git.infradead.org/linux-platform...
[sfrench/cifs-2.6.git] / drivers / platform / goldfish / goldfish_pipe.c
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         /* an irq tasklet to run goldfish_interrupt_task */
216         struct tasklet_struct irq_tasklet;
217
218         struct miscdevice miscdev;
219 };
220
221 static int goldfish_pipe_cmd_locked(struct goldfish_pipe *pipe,
222                                     enum PipeCmdCode cmd)
223 {
224         pipe->command_buffer->cmd = cmd;
225         /* failure by default */
226         pipe->command_buffer->status = PIPE_ERROR_INVAL;
227         writel(pipe->id, pipe->dev->base + PIPE_REG_CMD);
228         return pipe->command_buffer->status;
229 }
230
231 static int goldfish_pipe_cmd(struct goldfish_pipe *pipe, enum PipeCmdCode cmd)
232 {
233         int status;
234
235         if (mutex_lock_interruptible(&pipe->lock))
236                 return PIPE_ERROR_IO;
237         status = goldfish_pipe_cmd_locked(pipe, cmd);
238         mutex_unlock(&pipe->lock);
239         return status;
240 }
241
242 /*
243  * This function converts an error code returned by the emulator through
244  * the PIPE_REG_STATUS i/o register into a valid negative errno value.
245  */
246 static int goldfish_pipe_error_convert(int status)
247 {
248         switch (status) {
249         case PIPE_ERROR_AGAIN:
250                 return -EAGAIN;
251         case PIPE_ERROR_NOMEM:
252                 return -ENOMEM;
253         case PIPE_ERROR_IO:
254                 return -EIO;
255         default:
256                 return -EINVAL;
257         }
258 }
259
260 static int pin_user_pages(unsigned long first_page,
261                           unsigned long last_page,
262                           unsigned int last_page_size,
263                           int is_write,
264                           struct page *pages[MAX_BUFFERS_PER_COMMAND],
265                           unsigned int *iter_last_page_size)
266 {
267         int ret;
268         int requested_pages = ((last_page - first_page) >> PAGE_SHIFT) + 1;
269
270         if (requested_pages > MAX_BUFFERS_PER_COMMAND) {
271                 requested_pages = MAX_BUFFERS_PER_COMMAND;
272                 *iter_last_page_size = PAGE_SIZE;
273         } else {
274                 *iter_last_page_size = last_page_size;
275         }
276
277         ret = get_user_pages_fast(first_page, requested_pages, !is_write,
278                                   pages);
279         if (ret <= 0)
280                 return -EFAULT;
281         if (ret < requested_pages)
282                 *iter_last_page_size = PAGE_SIZE;
283
284         return ret;
285 }
286
287 static void release_user_pages(struct page **pages, int pages_count,
288                                int is_write, s32 consumed_size)
289 {
290         int i;
291
292         for (i = 0; i < pages_count; i++) {
293                 if (!is_write && consumed_size > 0)
294                         set_page_dirty(pages[i]);
295                 put_page(pages[i]);
296         }
297 }
298
299 /* Populate the call parameters, merging adjacent pages together */
300 static void populate_rw_params(struct page **pages,
301                                int pages_count,
302                                unsigned long address,
303                                unsigned long address_end,
304                                unsigned long first_page,
305                                unsigned long last_page,
306                                unsigned int iter_last_page_size,
307                                int is_write,
308                                struct goldfish_pipe_command *command)
309 {
310         /*
311          * Process the first page separately - it's the only page that
312          * needs special handling for its start address.
313          */
314         unsigned long xaddr = page_to_phys(pages[0]);
315         unsigned long xaddr_prev = xaddr;
316         int buffer_idx = 0;
317         int i = 1;
318         int size_on_page = first_page == last_page
319                         ? (int)(address_end - address)
320                         : (PAGE_SIZE - (address & ~PAGE_MASK));
321         command->rw_params.ptrs[0] = (u64)(xaddr | (address & ~PAGE_MASK));
322         command->rw_params.sizes[0] = size_on_page;
323         for (; i < pages_count; ++i) {
324                 xaddr = page_to_phys(pages[i]);
325                 size_on_page = (i == pages_count - 1) ?
326                         iter_last_page_size : PAGE_SIZE;
327                 if (xaddr == xaddr_prev + PAGE_SIZE) {
328                         command->rw_params.sizes[buffer_idx] += size_on_page;
329                 } else {
330                         ++buffer_idx;
331                         command->rw_params.ptrs[buffer_idx] = (u64)xaddr;
332                         command->rw_params.sizes[buffer_idx] = size_on_page;
333                 }
334                 xaddr_prev = xaddr;
335         }
336         command->rw_params.buffers_count = buffer_idx + 1;
337 }
338
339 static int transfer_max_buffers(struct goldfish_pipe *pipe,
340                                 unsigned long address,
341                                 unsigned long address_end,
342                                 int is_write,
343                                 unsigned long last_page,
344                                 unsigned int last_page_size,
345                                 s32 *consumed_size,
346                                 int *status)
347 {
348         unsigned long first_page = address & PAGE_MASK;
349         unsigned int iter_last_page_size;
350         int pages_count;
351
352         /* Serialize access to the pipe command buffers */
353         if (mutex_lock_interruptible(&pipe->lock))
354                 return -ERESTARTSYS;
355
356         pages_count = pin_user_pages(first_page, last_page,
357                                      last_page_size, is_write,
358                                      pipe->pages, &iter_last_page_size);
359         if (pages_count < 0) {
360                 mutex_unlock(&pipe->lock);
361                 return pages_count;
362         }
363
364         populate_rw_params(pipe->pages, pages_count, address, address_end,
365                            first_page, last_page, iter_last_page_size, is_write,
366                            pipe->command_buffer);
367
368         /* Transfer the data */
369         *status = goldfish_pipe_cmd_locked(pipe,
370                                 is_write ? PIPE_CMD_WRITE : PIPE_CMD_READ);
371
372         *consumed_size = pipe->command_buffer->rw_params.consumed_size;
373
374         release_user_pages(pipe->pages, pages_count, is_write, *consumed_size);
375
376         mutex_unlock(&pipe->lock);
377         return 0;
378 }
379
380 static int wait_for_host_signal(struct goldfish_pipe *pipe, int is_write)
381 {
382         u32 wake_bit = is_write ? BIT_WAKE_ON_WRITE : BIT_WAKE_ON_READ;
383
384         set_bit(wake_bit, &pipe->flags);
385
386         /* Tell the emulator we're going to wait for a wake event */
387         goldfish_pipe_cmd(pipe,
388                 is_write ? PIPE_CMD_WAKE_ON_WRITE : PIPE_CMD_WAKE_ON_READ);
389
390         while (test_bit(wake_bit, &pipe->flags)) {
391                 if (wait_event_interruptible(pipe->wake_queue,
392                                              !test_bit(wake_bit, &pipe->flags)))
393                         return -ERESTARTSYS;
394
395                 if (test_bit(BIT_CLOSED_ON_HOST, &pipe->flags))
396                         return -EIO;
397         }
398
399         return 0;
400 }
401
402 static ssize_t goldfish_pipe_read_write(struct file *filp,
403                                         char __user *buffer,
404                                         size_t bufflen,
405                                         int is_write)
406 {
407         struct goldfish_pipe *pipe = filp->private_data;
408         int count = 0, ret = -EINVAL;
409         unsigned long address, address_end, last_page;
410         unsigned int last_page_size;
411
412         /* If the emulator already closed the pipe, no need to go further */
413         if (unlikely(test_bit(BIT_CLOSED_ON_HOST, &pipe->flags)))
414                 return -EIO;
415         /* Null reads or writes succeeds */
416         if (unlikely(bufflen == 0))
417                 return 0;
418         /* Check the buffer range for access */
419         if (unlikely(!access_ok(is_write ? VERIFY_WRITE : VERIFY_READ,
420                                 buffer, bufflen)))
421                 return -EFAULT;
422
423         address = (unsigned long)buffer;
424         address_end = address + bufflen;
425         last_page = (address_end - 1) & PAGE_MASK;
426         last_page_size = ((address_end - 1) & ~PAGE_MASK) + 1;
427
428         while (address < address_end) {
429                 s32 consumed_size;
430                 int status;
431
432                 ret = transfer_max_buffers(pipe, address, address_end, is_write,
433                                            last_page, last_page_size,
434                                            &consumed_size, &status);
435                 if (ret < 0)
436                         break;
437
438                 if (consumed_size > 0) {
439                         /* No matter what's the status, we've transferred
440                          * something.
441                          */
442                         count += consumed_size;
443                         address += consumed_size;
444                 }
445                 if (status > 0)
446                         continue;
447                 if (status == 0) {
448                         /* EOF */
449                         ret = 0;
450                         break;
451                 }
452                 if (count > 0) {
453                         /*
454                          * An error occurred, but we already transferred
455                          * something on one of the previous iterations.
456                          * Just return what we already copied and log this
457                          * err.
458                          */
459                         if (status != PIPE_ERROR_AGAIN)
460                                 dev_err_ratelimited(pipe->dev->pdev_dev,
461                                         "backend error %d on %s\n",
462                                         status, is_write ? "write" : "read");
463                         break;
464                 }
465
466                 /*
467                  * If the error is not PIPE_ERROR_AGAIN, or if we are in
468                  * non-blocking mode, just return the error code.
469                  */
470                 if (status != PIPE_ERROR_AGAIN ||
471                         (filp->f_flags & O_NONBLOCK) != 0) {
472                         ret = goldfish_pipe_error_convert(status);
473                         break;
474                 }
475
476                 status = wait_for_host_signal(pipe, is_write);
477                 if (status < 0)
478                         return status;
479         }
480
481         if (count > 0)
482                 return count;
483         return ret;
484 }
485
486 static ssize_t goldfish_pipe_read(struct file *filp, char __user *buffer,
487                                   size_t bufflen, loff_t *ppos)
488 {
489         return goldfish_pipe_read_write(filp, buffer, bufflen,
490                                         /* is_write */ 0);
491 }
492
493 static ssize_t goldfish_pipe_write(struct file *filp,
494                                    const char __user *buffer, size_t bufflen,
495                                    loff_t *ppos)
496 {
497         /* cast away the const */
498         char __user *no_const_buffer = (char __user *)buffer;
499
500         return goldfish_pipe_read_write(filp, no_const_buffer, bufflen,
501                                         /* is_write */ 1);
502 }
503
504 static __poll_t goldfish_pipe_poll(struct file *filp, poll_table *wait)
505 {
506         struct goldfish_pipe *pipe = filp->private_data;
507         __poll_t mask = 0;
508         int status;
509
510         poll_wait(filp, &pipe->wake_queue, wait);
511
512         status = goldfish_pipe_cmd(pipe, PIPE_CMD_POLL);
513         if (status < 0)
514                 return -ERESTARTSYS;
515
516         if (status & PIPE_POLL_IN)
517                 mask |= EPOLLIN | EPOLLRDNORM;
518         if (status & PIPE_POLL_OUT)
519                 mask |= EPOLLOUT | EPOLLWRNORM;
520         if (status & PIPE_POLL_HUP)
521                 mask |= EPOLLHUP;
522         if (test_bit(BIT_CLOSED_ON_HOST, &pipe->flags))
523                 mask |= EPOLLERR;
524
525         return mask;
526 }
527
528 static void signalled_pipes_add_locked(struct goldfish_pipe_dev *dev,
529                                        u32 id, u32 flags)
530 {
531         struct goldfish_pipe *pipe;
532
533         if (WARN_ON(id >= dev->pipes_capacity))
534                 return;
535
536         pipe = dev->pipes[id];
537         if (!pipe)
538                 return;
539         pipe->signalled_flags |= flags;
540
541         if (pipe->prev_signalled || pipe->next_signalled ||
542                 dev->first_signalled_pipe == pipe)
543                 return; /* already in the list */
544         pipe->next_signalled = dev->first_signalled_pipe;
545         if (dev->first_signalled_pipe)
546                 dev->first_signalled_pipe->prev_signalled = pipe;
547         dev->first_signalled_pipe = pipe;
548 }
549
550 static void signalled_pipes_remove_locked(struct goldfish_pipe_dev *dev,
551                                           struct goldfish_pipe *pipe)
552 {
553         if (pipe->prev_signalled)
554                 pipe->prev_signalled->next_signalled = pipe->next_signalled;
555         if (pipe->next_signalled)
556                 pipe->next_signalled->prev_signalled = pipe->prev_signalled;
557         if (pipe == dev->first_signalled_pipe)
558                 dev->first_signalled_pipe = pipe->next_signalled;
559         pipe->prev_signalled = NULL;
560         pipe->next_signalled = NULL;
561 }
562
563 static struct goldfish_pipe *signalled_pipes_pop_front(
564                 struct goldfish_pipe_dev *dev, int *wakes)
565 {
566         struct goldfish_pipe *pipe;
567         unsigned long flags;
568
569         spin_lock_irqsave(&dev->lock, flags);
570
571         pipe = dev->first_signalled_pipe;
572         if (pipe) {
573                 *wakes = pipe->signalled_flags;
574                 pipe->signalled_flags = 0;
575                 /*
576                  * This is an optimized version of
577                  * signalled_pipes_remove_locked()
578                  * - We want to make it as fast as possible to
579                  * wake the sleeping pipe operations faster.
580                  */
581                 dev->first_signalled_pipe = pipe->next_signalled;
582                 if (dev->first_signalled_pipe)
583                         dev->first_signalled_pipe->prev_signalled = NULL;
584                 pipe->next_signalled = NULL;
585         }
586
587         spin_unlock_irqrestore(&dev->lock, flags);
588         return pipe;
589 }
590
591 static void goldfish_interrupt_task(unsigned long dev_addr)
592 {
593         /* Iterate over the signalled pipes and wake them one by one */
594         struct goldfish_pipe_dev *dev = (struct goldfish_pipe_dev *)dev_addr;
595         struct goldfish_pipe *pipe;
596         int wakes;
597
598         while ((pipe = signalled_pipes_pop_front(dev, &wakes)) != NULL) {
599                 if (wakes & PIPE_WAKE_CLOSED) {
600                         pipe->flags = 1 << BIT_CLOSED_ON_HOST;
601                 } else {
602                         if (wakes & PIPE_WAKE_READ)
603                                 clear_bit(BIT_WAKE_ON_READ, &pipe->flags);
604                         if (wakes & PIPE_WAKE_WRITE)
605                                 clear_bit(BIT_WAKE_ON_WRITE, &pipe->flags);
606                 }
607                 /*
608                  * wake_up_interruptible() implies a write barrier, so don't
609                  * explicitly add another one here.
610                  */
611                 wake_up_interruptible(&pipe->wake_queue);
612         }
613 }
614
615 static void goldfish_pipe_device_deinit(struct platform_device *pdev,
616                                         struct goldfish_pipe_dev *dev);
617
618 /*
619  * The general idea of the interrupt handling:
620  *
621  *  1. device raises an interrupt if there's at least one signalled pipe
622  *  2. IRQ handler reads the signalled pipes and their count from the device
623  *  3. device writes them into a shared buffer and returns the count
624  *      it only resets the IRQ if it has returned all signalled pipes,
625  *      otherwise it leaves it raised, so IRQ handler will be called
626  *      again for the next chunk
627  *  4. IRQ handler adds all returned pipes to the device's signalled pipes list
628  *  5. IRQ handler launches a tasklet to process the signalled pipes from the
629  *      list in a separate context
630  */
631 static irqreturn_t goldfish_pipe_interrupt(int irq, void *dev_id)
632 {
633         u32 count;
634         u32 i;
635         unsigned long flags;
636         struct goldfish_pipe_dev *dev = dev_id;
637
638         if (dev->magic != &goldfish_pipe_device_deinit)
639                 return IRQ_NONE;
640
641         /* Request the signalled pipes from the device */
642         spin_lock_irqsave(&dev->lock, flags);
643
644         count = readl(dev->base + PIPE_REG_GET_SIGNALLED);
645         if (count == 0) {
646                 spin_unlock_irqrestore(&dev->lock, flags);
647                 return IRQ_NONE;
648         }
649         if (count > MAX_SIGNALLED_PIPES)
650                 count = MAX_SIGNALLED_PIPES;
651
652         for (i = 0; i < count; ++i)
653                 signalled_pipes_add_locked(dev,
654                         dev->buffers->signalled_pipe_buffers[i].id,
655                         dev->buffers->signalled_pipe_buffers[i].flags);
656
657         spin_unlock_irqrestore(&dev->lock, flags);
658
659         tasklet_schedule(&dev->irq_tasklet);
660         return IRQ_HANDLED;
661 }
662
663 static int get_free_pipe_id_locked(struct goldfish_pipe_dev *dev)
664 {
665         int id;
666
667         for (id = 0; id < dev->pipes_capacity; ++id)
668                 if (!dev->pipes[id])
669                         return id;
670
671         {
672                 /* Reallocate the array.
673                  * Since get_free_pipe_id_locked runs with interrupts disabled,
674                  * we don't want to make calls that could lead to sleep.
675                  */
676                 u32 new_capacity = 2 * dev->pipes_capacity;
677                 struct goldfish_pipe **pipes =
678                         kcalloc(new_capacity, sizeof(*pipes), GFP_ATOMIC);
679                 if (!pipes)
680                         return -ENOMEM;
681                 memcpy(pipes, dev->pipes, sizeof(*pipes) * dev->pipes_capacity);
682                 kfree(dev->pipes);
683                 dev->pipes = pipes;
684                 id = dev->pipes_capacity;
685                 dev->pipes_capacity = new_capacity;
686         }
687         return id;
688 }
689
690 /* A helper function to get the instance of goldfish_pipe_dev from file */
691 static struct goldfish_pipe_dev *to_goldfish_pipe_dev(struct file *file)
692 {
693         struct miscdevice *miscdev = file->private_data;
694
695         return container_of(miscdev, struct goldfish_pipe_dev, miscdev);
696 }
697
698 /**
699  *      goldfish_pipe_open - open a channel to the AVD
700  *      @inode: inode of device
701  *      @file: file struct of opener
702  *
703  *      Create a new pipe link between the emulator and the use application.
704  *      Each new request produces a new pipe.
705  *
706  *      Note: we use the pipe ID as a mux. All goldfish emulations are 32bit
707  *      right now so this is fine. A move to 64bit will need this addressing
708  */
709 static int goldfish_pipe_open(struct inode *inode, struct file *file)
710 {
711         struct goldfish_pipe_dev *dev = to_goldfish_pipe_dev(file);
712         unsigned long flags;
713         int id;
714         int status;
715
716         /* Allocate new pipe kernel object */
717         struct goldfish_pipe *pipe = kzalloc(sizeof(*pipe), GFP_KERNEL);
718
719         if (!pipe)
720                 return -ENOMEM;
721
722         pipe->dev = dev;
723         mutex_init(&pipe->lock);
724         init_waitqueue_head(&pipe->wake_queue);
725
726         /*
727          * Command buffer needs to be allocated on its own page to make sure
728          * it is physically contiguous in host's address space.
729          */
730         BUILD_BUG_ON(sizeof(struct goldfish_pipe_command) > PAGE_SIZE);
731         pipe->command_buffer =
732                 (struct goldfish_pipe_command *)__get_free_page(GFP_KERNEL);
733         if (!pipe->command_buffer) {
734                 status = -ENOMEM;
735                 goto err_pipe;
736         }
737
738         spin_lock_irqsave(&dev->lock, flags);
739
740         id = get_free_pipe_id_locked(dev);
741         if (id < 0) {
742                 status = id;
743                 goto err_id_locked;
744         }
745
746         dev->pipes[id] = pipe;
747         pipe->id = id;
748         pipe->command_buffer->id = id;
749
750         /* Now tell the emulator we're opening a new pipe. */
751         dev->buffers->open_command_params.rw_params_max_count =
752                         MAX_BUFFERS_PER_COMMAND;
753         dev->buffers->open_command_params.command_buffer_ptr =
754                         (u64)(unsigned long)__pa(pipe->command_buffer);
755         status = goldfish_pipe_cmd_locked(pipe, PIPE_CMD_OPEN);
756         spin_unlock_irqrestore(&dev->lock, flags);
757         if (status < 0)
758                 goto err_cmd;
759         /* All is done, save the pipe into the file's private data field */
760         file->private_data = pipe;
761         return 0;
762
763 err_cmd:
764         spin_lock_irqsave(&dev->lock, flags);
765         dev->pipes[id] = NULL;
766 err_id_locked:
767         spin_unlock_irqrestore(&dev->lock, flags);
768         free_page((unsigned long)pipe->command_buffer);
769 err_pipe:
770         kfree(pipe);
771         return status;
772 }
773
774 static int goldfish_pipe_release(struct inode *inode, struct file *filp)
775 {
776         unsigned long flags;
777         struct goldfish_pipe *pipe = filp->private_data;
778         struct goldfish_pipe_dev *dev = pipe->dev;
779
780         /* The guest is closing the channel, so tell the emulator right now */
781         goldfish_pipe_cmd(pipe, PIPE_CMD_CLOSE);
782
783         spin_lock_irqsave(&dev->lock, flags);
784         dev->pipes[pipe->id] = NULL;
785         signalled_pipes_remove_locked(dev, pipe);
786         spin_unlock_irqrestore(&dev->lock, flags);
787
788         filp->private_data = NULL;
789         free_page((unsigned long)pipe->command_buffer);
790         kfree(pipe);
791         return 0;
792 }
793
794 static const struct file_operations goldfish_pipe_fops = {
795         .owner = THIS_MODULE,
796         .read = goldfish_pipe_read,
797         .write = goldfish_pipe_write,
798         .poll = goldfish_pipe_poll,
799         .open = goldfish_pipe_open,
800         .release = goldfish_pipe_release,
801 };
802
803 static void init_miscdevice(struct miscdevice *miscdev)
804 {
805         memset(miscdev, 0, sizeof(*miscdev));
806
807         miscdev->minor = MISC_DYNAMIC_MINOR;
808         miscdev->name = "goldfish_pipe";
809         miscdev->fops = &goldfish_pipe_fops;
810 }
811
812 static void write_pa_addr(void *addr, void __iomem *portl, void __iomem *porth)
813 {
814         const unsigned long paddr = __pa(addr);
815
816         writel(upper_32_bits(paddr), porth);
817         writel(lower_32_bits(paddr), portl);
818 }
819
820 static int goldfish_pipe_device_init(struct platform_device *pdev,
821                                      struct goldfish_pipe_dev *dev)
822 {
823         int err;
824
825         tasklet_init(&dev->irq_tasklet, &goldfish_interrupt_task,
826                      (unsigned long)dev);
827
828         err = devm_request_irq(&pdev->dev, dev->irq,
829                                goldfish_pipe_interrupt,
830                                IRQF_SHARED, "goldfish_pipe", dev);
831         if (err) {
832                 dev_err(&pdev->dev, "unable to allocate IRQ for v2\n");
833                 return err;
834         }
835
836         init_miscdevice(&dev->miscdev);
837         err = misc_register(&dev->miscdev);
838         if (err) {
839                 dev_err(&pdev->dev, "unable to register v2 device\n");
840                 return err;
841         }
842
843         dev->pdev_dev = &pdev->dev;
844         dev->first_signalled_pipe = NULL;
845         dev->pipes_capacity = INITIAL_PIPES_CAPACITY;
846         dev->pipes = kcalloc(dev->pipes_capacity, sizeof(*dev->pipes),
847                              GFP_KERNEL);
848         if (!dev->pipes) {
849                 misc_deregister(&dev->miscdev);
850                 return -ENOMEM;
851         }
852
853         /*
854          * We're going to pass two buffers, open_command_params and
855          * signalled_pipe_buffers, to the host. This means each of those buffers
856          * needs to be contained in a single physical page. The easiest choice
857          * is to just allocate a page and place the buffers in it.
858          */
859         BUILD_BUG_ON(sizeof(struct goldfish_pipe_dev_buffers) > PAGE_SIZE);
860         dev->buffers = (struct goldfish_pipe_dev_buffers *)
861                 __get_free_page(GFP_KERNEL);
862         if (!dev->buffers) {
863                 kfree(dev->pipes);
864                 misc_deregister(&dev->miscdev);
865                 return -ENOMEM;
866         }
867
868         /* Send the buffer addresses to the host */
869         write_pa_addr(&dev->buffers->signalled_pipe_buffers,
870                       dev->base + PIPE_REG_SIGNAL_BUFFER,
871                       dev->base + PIPE_REG_SIGNAL_BUFFER_HIGH);
872
873         writel(MAX_SIGNALLED_PIPES,
874                dev->base + PIPE_REG_SIGNAL_BUFFER_COUNT);
875
876         write_pa_addr(&dev->buffers->open_command_params,
877                       dev->base + PIPE_REG_OPEN_BUFFER,
878                       dev->base + PIPE_REG_OPEN_BUFFER_HIGH);
879
880         platform_set_drvdata(pdev, dev);
881         return 0;
882 }
883
884 static void goldfish_pipe_device_deinit(struct platform_device *pdev,
885                                         struct goldfish_pipe_dev *dev)
886 {
887         misc_deregister(&dev->miscdev);
888         tasklet_kill(&dev->irq_tasklet);
889         kfree(dev->pipes);
890         free_page((unsigned long)dev->buffers);
891 }
892
893 static int goldfish_pipe_probe(struct platform_device *pdev)
894 {
895         struct resource *r;
896         struct goldfish_pipe_dev *dev;
897
898         dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
899         if (!dev)
900                 return -ENOMEM;
901
902         dev->magic = &goldfish_pipe_device_deinit;
903         spin_lock_init(&dev->lock);
904
905         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
906         if (!r || resource_size(r) < PAGE_SIZE) {
907                 dev_err(&pdev->dev, "can't allocate i/o page\n");
908                 return -EINVAL;
909         }
910         dev->base = devm_ioremap(&pdev->dev, r->start, PAGE_SIZE);
911         if (!dev->base) {
912                 dev_err(&pdev->dev, "ioremap failed\n");
913                 return -EINVAL;
914         }
915
916         r = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
917         if (!r)
918                 return -EINVAL;
919
920         dev->irq = r->start;
921
922         /*
923          * Exchange the versions with the host device
924          *
925          * Note: v1 driver used to not report its version, so we write it before
926          *  reading device version back: this allows the host implementation to
927          *  detect the old driver (if there was no version write before read).
928          */
929         writel(PIPE_DRIVER_VERSION, dev->base + PIPE_REG_VERSION);
930         dev->version = readl(dev->base + PIPE_REG_VERSION);
931         if (WARN_ON(dev->version < PIPE_CURRENT_DEVICE_VERSION))
932                 return -EINVAL;
933
934         return goldfish_pipe_device_init(pdev, dev);
935 }
936
937 static int goldfish_pipe_remove(struct platform_device *pdev)
938 {
939         struct goldfish_pipe_dev *dev = platform_get_drvdata(pdev);
940
941         goldfish_pipe_device_deinit(pdev, dev);
942         return 0;
943 }
944
945 static const struct acpi_device_id goldfish_pipe_acpi_match[] = {
946         { "GFSH0003", 0 },
947         { },
948 };
949 MODULE_DEVICE_TABLE(acpi, goldfish_pipe_acpi_match);
950
951 static const struct of_device_id goldfish_pipe_of_match[] = {
952         { .compatible = "google,android-pipe", },
953         {},
954 };
955 MODULE_DEVICE_TABLE(of, goldfish_pipe_of_match);
956
957 static struct platform_driver goldfish_pipe_driver = {
958         .probe = goldfish_pipe_probe,
959         .remove = goldfish_pipe_remove,
960         .driver = {
961                 .name = "goldfish_pipe",
962                 .of_match_table = goldfish_pipe_of_match,
963                 .acpi_match_table = ACPI_PTR(goldfish_pipe_acpi_match),
964         }
965 };
966
967 module_platform_driver(goldfish_pipe_driver);
968 MODULE_AUTHOR("David Turner <digit@google.com>");
969 MODULE_LICENSE("GPL v2");