drivers/media/video/videobuf-dma-contig.c

   1 /*
   2  * helper functions for physically contiguous capture buffers
   3  *
   4  * The functions support hardware lacking scatter gather support
   5  * (i.e. the buffers must be linear in physical memory)
   6  *
   7  * Copyright (c) 2008 Magnus Damm
   8  *
   9  * Based on videobuf-vmalloc.c,
  10  * (c) 2007 Mauro Carvalho Chehab, <mchehab@infradead.org>
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2
  15  */
  16
  17 #include <linux/init.h>
  18 #include <linux/module.h>
  19 #include <linux/mm.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/dma-mapping.h>
  22 #include <linux/sched.h>
  23 #include <linux/slab.h>
  24 #include <media/videobuf-dma-contig.h>
  25
  26 struct videobuf_dma_contig_memory {
  27         u32 magic;
  28         void *vaddr;
  29         dma_addr_t dma_handle;
  30         bool cached;
  31         unsigned long size;
  32 };
  33
  34 #define MAGIC_DC_MEM 0x0733ac61
  35 #define MAGIC_CHECK(is, should)                                             \
  36         if (unlikely((is) != (should))) {                                   \
  37                 pr_err("magic mismatch: %x expected %x\n", (is), (should)); \
  38                 BUG();                                                      \
  39         }
  40
  41 static int __videobuf_dc_alloc(struct device *dev,
  42                                struct videobuf_dma_contig_memory *mem,
  43                                unsigned long size, unsigned long flags)
  44 {
  45         mem->size = size;
  46         if (mem->cached) {
  47                 mem->vaddr = alloc_pages_exact(mem->size, flags | GFP_DMA);
  48                 if (mem->vaddr) {
  49                         int err;
  50
  51                         mem->dma_handle = dma_map_single(dev, mem->vaddr,
  52                                                          mem->size,
  53                                                          DMA_FROM_DEVICE);
  54                         err = dma_mapping_error(dev, mem->dma_handle);
  55                         if (err) {
  56                                 dev_err(dev, "dma_map_single failed\n");
  57
  58                                 free_pages_exact(mem->vaddr, mem->size);
  59                                 mem->vaddr = 0;
  60                                 return err;
  61                         }
  62                 }
  63         } else
  64                 mem->vaddr = dma_alloc_coherent(dev, mem->size,
  65                                                 &mem->dma_handle, flags);
  66
  67         if (!mem->vaddr) {
  68                 dev_err(dev, "memory alloc size %ld failed\n", mem->size);
  69                 return -ENOMEM;
  70         }
  71
  72         dev_dbg(dev, "dma mapped data is at %p (%ld)\n", mem->vaddr, mem->size);
  73
  74         return 0;
  75 }
  76
  77 static void __videobuf_dc_free(struct device *dev,
  78                                struct videobuf_dma_contig_memory *mem)
  79 {
  80         if (mem->cached) {
  81                 if (!mem->vaddr)
  82                         return;
  83                 dma_unmap_single(dev, mem->dma_handle, mem->size,
  84                                  DMA_FROM_DEVICE);
  85                 free_pages_exact(mem->vaddr, mem->size);
  86         } else
  87                 dma_free_coherent(dev, mem->size, mem->vaddr, mem->dma_handle);
  88
  89         mem->vaddr = NULL;
  90 }
  91
  92 static void videobuf_vm_open(struct vm_area_struct *vma)
  93 {
  94         struct videobuf_mapping *map = vma->vm_private_data;
  95
  96         dev_dbg(map->q->dev, "vm_open %p [count=%u,vma=%08lx-%08lx]\n",
  97                 map, map->count, vma->vm_start, vma->vm_end);
  98
  99         map->count++;
 100 }
 101
 102 static void videobuf_vm_close(struct vm_area_struct *vma)
 103 {
 104         struct videobuf_mapping *map = vma->vm_private_data;
 105         struct videobuf_queue *q = map->q;
 106         int i;
 107
 108         dev_dbg(q->dev, "vm_close %p [count=%u,vma=%08lx-%08lx]\n",
 109                 map, map->count, vma->vm_start, vma->vm_end);
 110
 111         map->count--;
 112         if (0 == map->count) {
 113                 struct videobuf_dma_contig_memory *mem;
 114
 115                 dev_dbg(q->dev, "munmap %p q=%p\n", map, q);
 116                 videobuf_queue_lock(q);
 117
 118                 /* We need first to cancel streams, before unmapping */
 119                 if (q->streaming)
 120                         videobuf_queue_cancel(q);
 121
 122                 for (i = 0; i < VIDEO_MAX_FRAME; i++) {
 123                         if (NULL == q->bufs[i])
 124                                 continue;
 125
 126                         if (q->bufs[i]->map != map)
 127                                 continue;
 128
 129                         mem = q->bufs[i]->priv;
 130                         if (mem) {
 131                                 /* This callback is called only if kernel has
 132                                    allocated memory and this memory is mmapped.
 133                                    In this case, memory should be freed,
 134                                    in order to do memory unmap.
 135                                  */
 136
 137                                 MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 138
 139                                 /* vfree is not atomic - can't be
 140                                    called with IRQ's disabled
 141                                  */
 142                                 dev_dbg(q->dev, "buf[%d] freeing %p\n",
 143                                         i, mem->vaddr);
 144
 145                                 __videobuf_dc_free(q->dev, mem);
 146                                 mem->vaddr = NULL;
 147                         }
 148
 149                         q->bufs[i]->map = NULL;
 150                         q->bufs[i]->baddr = 0;
 151                 }
 152
 153                 kfree(map);
 154
 155                 videobuf_queue_unlock(q);
 156         }
 157 }
 158
 159 static const struct vm_operations_struct videobuf_vm_ops = {
 160         .open   = videobuf_vm_open,
 161         .close  = videobuf_vm_close,
 162 };
 163
 164 /**
 165  * videobuf_dma_contig_user_put() - reset pointer to user space buffer
 166  * @mem: per-buffer private videobuf-dma-contig data
 167  *
 168  * This function resets the user space pointer
 169  */
 170 static void videobuf_dma_contig_user_put(struct videobuf_dma_contig_memory *mem)
 171 {
 172         mem->dma_handle = 0;
 173         mem->size = 0;
 174 }
 175
 176 /**
 177  * videobuf_dma_contig_user_get() - setup user space memory pointer
 178  * @mem: per-buffer private videobuf-dma-contig data
 179  * @vb: video buffer to map
 180  *
 181  * This function validates and sets up a pointer to user space memory.
 182  * Only physically contiguous pfn-mapped memory is accepted.
 183  *
 184  * Returns 0 if successful.
 185  */
 186 static int videobuf_dma_contig_user_get(struct videobuf_dma_contig_memory *mem,
 187                                         struct videobuf_buffer *vb)
 188 {
 189         struct mm_struct *mm = current->mm;
 190         struct vm_area_struct *vma;
 191         unsigned long prev_pfn, this_pfn;
 192         unsigned long pages_done, user_address;
 193         unsigned int offset;
 194         int ret;
 195
 196         offset = vb->baddr & ~PAGE_MASK;
 197         mem->size = PAGE_ALIGN(vb->size + offset);
 198         ret = -EINVAL;
 199
 200         down_read(&mm->mmap_sem);
 201
 202         vma = find_vma(mm, vb->baddr);
 203         if (!vma)
 204                 goto out_up;
 205
 206         if ((vb->baddr + mem->size) > vma->vm_end)
 207                 goto out_up;
 208
 209         pages_done = 0;
 210         prev_pfn = 0; /* kill warning */
 211         user_address = vb->baddr;
 212
 213         while (pages_done < (mem->size >> PAGE_SHIFT)) {
 214                 ret = follow_pfn(vma, user_address, &this_pfn);
 215                 if (ret)
 216                         break;
 217
 218                 if (pages_done == 0)
 219                         mem->dma_handle = (this_pfn << PAGE_SHIFT) + offset;
 220                 else if (this_pfn != (prev_pfn + 1))
 221                         ret = -EFAULT;
 222
 223                 if (ret)
 224                         break;
 225
 226                 prev_pfn = this_pfn;
 227                 user_address += PAGE_SIZE;
 228                 pages_done++;
 229         }
 230
 231 out_up:
 232         up_read(&current->mm->mmap_sem);
 233
 234         return ret;
 235 }
 236
 237 static struct videobuf_buffer *__videobuf_alloc_vb(size_t size, bool cached)
 238 {
 239         struct videobuf_dma_contig_memory *mem;
 240         struct videobuf_buffer *vb;
 241
 242         vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
 243         if (vb) {
 244                 vb->priv = ((char *)vb) + size;
 245                 mem = vb->priv;
 246                 mem->magic = MAGIC_DC_MEM;
 247                 mem->cached = cached;
 248         }
 249
 250         return vb;
 251 }
 252
 253 static struct videobuf_buffer *__videobuf_alloc_uncached(size_t size)
 254 {
 255         return __videobuf_alloc_vb(size, false);
 256 }
 257
 258 static struct videobuf_buffer *__videobuf_alloc_cached(size_t size)
 259 {
 260         return __videobuf_alloc_vb(size, true);
 261 }
 262
 263 static void *__videobuf_to_vaddr(struct videobuf_buffer *buf)
 264 {
 265         struct videobuf_dma_contig_memory *mem = buf->priv;
 266
 267         BUG_ON(!mem);
 268         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 269
 270         return mem->vaddr;
 271 }
 272
 273 static int __videobuf_iolock(struct videobuf_queue *q,
 274                              struct videobuf_buffer *vb,
 275                              struct v4l2_framebuffer *fbuf)
 276 {
 277         struct videobuf_dma_contig_memory *mem = vb->priv;
 278
 279         BUG_ON(!mem);
 280         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 281
 282         switch (vb->memory) {
 283         case V4L2_MEMORY_MMAP:
 284                 dev_dbg(q->dev, "%s memory method MMAP\n", __func__);
 285
 286                 /* All handling should be done by __videobuf_mmap_mapper() */
 287                 if (!mem->vaddr) {
 288                         dev_err(q->dev, "memory is not alloced/mmapped.\n");
 289                         return -EINVAL;
 290                 }
 291                 break;
 292         case V4L2_MEMORY_USERPTR:
 293                 dev_dbg(q->dev, "%s memory method USERPTR\n", __func__);
 294
 295                 /* handle pointer from user space */
 296                 if (vb->baddr)
 297                         return videobuf_dma_contig_user_get(mem, vb);
 298
 299                 /* allocate memory for the read() method */
 300                 if (__videobuf_dc_alloc(q->dev, mem, PAGE_ALIGN(vb->size),
 301                                         GFP_KERNEL))
 302                         return -ENOMEM;
 303                 break;
 304         case V4L2_MEMORY_OVERLAY:
 305         default:
 306                 dev_dbg(q->dev, "%s memory method OVERLAY/unknown\n", __func__);
 307                 return -EINVAL;
 308         }
 309
 310         return 0;
 311 }
 312
 313 static int __videobuf_sync(struct videobuf_queue *q,
 314                            struct videobuf_buffer *buf)
 315 {
 316         struct videobuf_dma_contig_memory *mem = buf->priv;
 317         BUG_ON(!mem);
 318         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 319
 320         dma_sync_single_for_cpu(q->dev, mem->dma_handle, mem->size,
 321                                 DMA_FROM_DEVICE);
 322
 323         return 0;
 324 }
 325
 326 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
 327                                   struct videobuf_buffer *buf,
 328                                   struct vm_area_struct *vma)
 329 {
 330         struct videobuf_dma_contig_memory *mem;
 331         struct videobuf_mapping *map;
 332         int retval;
 333         unsigned long size;
 334         unsigned long pos, start = vma->vm_start;
 335         struct page *page;
 336
 337         dev_dbg(q->dev, "%s\n", __func__);
 338
 339         /* create mapping + update buffer list */
 340         map = kzalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
 341         if (!map)
 342                 return -ENOMEM;
 343
 344         buf->map = map;
 345         map->q = q;
 346
 347         buf->baddr = vma->vm_start;
 348
 349         mem = buf->priv;
 350         BUG_ON(!mem);
 351         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 352
 353         if (__videobuf_dc_alloc(q->dev, mem, PAGE_ALIGN(buf->bsize),
 354                                 GFP_KERNEL | __GFP_COMP))
 355                 goto error;
 356
 357         /* Try to remap memory */
 358
 359         size = vma->vm_end - vma->vm_start;
 360         size = (size < mem->size) ? size : mem->size;
 361
 362         if (!mem->cached)
 363                 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 364
 365         pos = (unsigned long)mem->vaddr;
 366
 367         while (size > 0) {
 368                 page = virt_to_page((void *)pos);
 369                 if (NULL == page) {
 370                         dev_err(q->dev, "mmap: virt_to_page failed\n");
 371                         __videobuf_dc_free(q->dev, mem);
 372                         goto error;
 373                 }
 374                 retval = vm_insert_page(vma, start, page);
 375                 if (retval) {
 376                         dev_err(q->dev, "mmap: insert failed with error %d\n",
 377                                 retval);
 378                         __videobuf_dc_free(q->dev, mem);
 379                         goto error;
 380                 }
 381                 start += PAGE_SIZE;
 382                 pos += PAGE_SIZE;
 383
 384                 if (size > PAGE_SIZE)
 385                         size -= PAGE_SIZE;
 386                 else
 387                         size = 0;
 388         }
 389
 390         vma->vm_ops = &videobuf_vm_ops;
 391         vma->vm_flags |= VM_DONTEXPAND;
 392         vma->vm_private_data = map;
 393
 394         dev_dbg(q->dev, "mmap %p: q=%p %08lx-%08lx (%lx) pgoff %08lx buf %d\n",
 395                 map, q, vma->vm_start, vma->vm_end,
 396                 (long int)buf->bsize, vma->vm_pgoff, buf->i);
 397
 398         videobuf_vm_open(vma);
 399
 400         return 0;
 401
 402 error:
 403         kfree(map);
 404         return -ENOMEM;
 405 }
 406
 407 static struct videobuf_qtype_ops qops = {
 408         .magic          = MAGIC_QTYPE_OPS,
 409         .alloc_vb       = __videobuf_alloc_uncached,
 410         .iolock         = __videobuf_iolock,
 411         .mmap_mapper    = __videobuf_mmap_mapper,
 412         .vaddr          = __videobuf_to_vaddr,
 413 };
 414
 415 static struct videobuf_qtype_ops qops_cached = {
 416         .magic          = MAGIC_QTYPE_OPS,
 417         .alloc_vb       = __videobuf_alloc_cached,
 418         .iolock         = __videobuf_iolock,
 419         .sync           = __videobuf_sync,
 420         .mmap_mapper    = __videobuf_mmap_mapper,
 421         .vaddr          = __videobuf_to_vaddr,
 422 };
 423
 424 void videobuf_queue_dma_contig_init(struct videobuf_queue *q,
 425                                     const struct videobuf_queue_ops *ops,
 426                                     struct device *dev,
 427                                     spinlock_t *irqlock,
 428                                     enum v4l2_buf_type type,
 429                                     enum v4l2_field field,
 430                                     unsigned int msize,
 431                                     void *priv,
 432                                     struct mutex *ext_lock)
 433 {
 434         videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
 435                                  priv, &qops, ext_lock);
 436 }
 437 EXPORT_SYMBOL_GPL(videobuf_queue_dma_contig_init);
 438
 439 void videobuf_queue_dma_contig_init_cached(struct videobuf_queue *q,
 440                                            const struct videobuf_queue_ops *ops,
 441                                            struct device *dev,
 442                                            spinlock_t *irqlock,
 443                                            enum v4l2_buf_type type,
 444                                            enum v4l2_field field,
 445                                            unsigned int msize,
 446                                            void *priv, struct mutex *ext_lock)
 447 {
 448         videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
 449                                  priv, &qops_cached, ext_lock);
 450 }
 451 EXPORT_SYMBOL_GPL(videobuf_queue_dma_contig_init_cached);
 452
 453 dma_addr_t videobuf_to_dma_contig(struct videobuf_buffer *buf)
 454 {
 455         struct videobuf_dma_contig_memory *mem = buf->priv;
 456
 457         BUG_ON(!mem);
 458         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 459
 460         return mem->dma_handle;
 461 }
 462 EXPORT_SYMBOL_GPL(videobuf_to_dma_contig);
 463
 464 void videobuf_dma_contig_free(struct videobuf_queue *q,
 465                               struct videobuf_buffer *buf)
 466 {
 467         struct videobuf_dma_contig_memory *mem = buf->priv;
 468
 469         /* mmapped memory can't be freed here, otherwise mmapped region
 470            would be released, while still needed. In this case, the memory
 471            release should happen inside videobuf_vm_close().
 472            So, it should free memory only if the memory were allocated for
 473            read() operation.
 474          */
 475         if (buf->memory != V4L2_MEMORY_USERPTR)
 476                 return;
 477
 478         if (!mem)
 479                 return;
 480
 481         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 482
 483         /* handle user space pointer case */
 484         if (buf->baddr) {
 485                 videobuf_dma_contig_user_put(mem);
 486                 return;
 487         }
 488
 489         /* read() method */
 490         if (mem->vaddr) {
 491                 __videobuf_dc_free(q->dev, mem);
 492                 mem->vaddr = NULL;
 493         }
 494 }
 495 EXPORT_SYMBOL_GPL(videobuf_dma_contig_free);
 496
 497 MODULE_DESCRIPTION("helper module to manage video4linux dma contig buffers");
 498 MODULE_AUTHOR("Magnus Damm");
 499 MODULE_LICENSE("GPL");