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