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         unsigned long size;
  31         int is_userptr;
  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 void
  42 videobuf_vm_open(struct vm_area_struct *vma)
  43 {
  44         struct videobuf_mapping *map = vma->vm_private_data;
  45
  46         dev_dbg(map->q->dev, "vm_open %p [count=%u,vma=%08lx-%08lx]\n",
  47                 map, map->count, vma->vm_start, vma->vm_end);
  48
  49         map->count++;
  50 }
  51
  52 static void videobuf_vm_close(struct vm_area_struct *vma)
  53 {
  54         struct videobuf_mapping *map = vma->vm_private_data;
  55         struct videobuf_queue *q = map->q;
  56         int i;
  57
  58         dev_dbg(q->dev, "vm_close %p [count=%u,vma=%08lx-%08lx]\n",
  59                 map, map->count, vma->vm_start, vma->vm_end);
  60
  61         map->count--;
  62         if (0 == map->count) {
  63                 struct videobuf_dma_contig_memory *mem;
  64
  65                 dev_dbg(q->dev, "munmap %p q=%p\n", map, q);
  66                 mutex_lock(&q->vb_lock);
  67
  68                 /* We need first to cancel streams, before unmapping */
  69                 if (q->streaming)
  70                         videobuf_queue_cancel(q);
  71
  72                 for (i = 0; i < VIDEO_MAX_FRAME; i++) {
  73                         if (NULL == q->bufs[i])
  74                                 continue;
  75
  76                         if (q->bufs[i]->map != map)
  77                                 continue;
  78
  79                         mem = q->bufs[i]->priv;
  80                         if (mem) {
  81                                 /* This callback is called only if kernel has
  82                                    allocated memory and this memory is mmapped.
  83                                    In this case, memory should be freed,
  84                                    in order to do memory unmap.
  85                                  */
  86
  87                                 MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
  88
  89                                 /* vfree is not atomic - can't be
  90                                    called with IRQ's disabled
  91                                  */
  92                                 dev_dbg(q->dev, "buf[%d] freeing %p\n",
  93                                         i, mem->vaddr);
  94
  95                                 dma_free_coherent(q->dev, mem->size,
  96                                                   mem->vaddr, mem->dma_handle);
  97                                 mem->vaddr = NULL;
  98                         }
  99
 100                         q->bufs[i]->map   = NULL;
 101                         q->bufs[i]->baddr = 0;
 102                 }
 103
 104                 kfree(map);
 105
 106                 mutex_unlock(&q->vb_lock);
 107         }
 108 }
 109
 110 static const struct vm_operations_struct videobuf_vm_ops = {
 111         .open     = videobuf_vm_open,
 112         .close    = videobuf_vm_close,
 113 };
 114
 115 /**
 116  * videobuf_dma_contig_user_put() - reset pointer to user space buffer
 117  * @mem: per-buffer private videobuf-dma-contig data
 118  *
 119  * This function resets the user space pointer
 120  */
 121 static void videobuf_dma_contig_user_put(struct videobuf_dma_contig_memory *mem)
 122 {
 123         mem->is_userptr = 0;
 124         mem->dma_handle = 0;
 125         mem->size = 0;
 126 }
 127
 128 /**
 129  * videobuf_dma_contig_user_get() - setup user space memory pointer
 130  * @mem: per-buffer private videobuf-dma-contig data
 131  * @vb: video buffer to map
 132  *
 133  * This function validates and sets up a pointer to user space memory.
 134  * Only physically contiguous pfn-mapped memory is accepted.
 135  *
 136  * Returns 0 if successful.
 137  */
 138 static int videobuf_dma_contig_user_get(struct videobuf_dma_contig_memory *mem,
 139                                         struct videobuf_buffer *vb)
 140 {
 141         struct mm_struct *mm = current->mm;
 142         struct vm_area_struct *vma;
 143         unsigned long prev_pfn, this_pfn;
 144         unsigned long pages_done, user_address;
 145         unsigned int offset;
 146         int ret;
 147
 148         offset = vb->baddr & ~PAGE_MASK;
 149         mem->size = PAGE_ALIGN(vb->size + offset);
 150         mem->is_userptr = 0;
 151         ret = -EINVAL;
 152
 153         down_read(&mm->mmap_sem);
 154
 155         vma = find_vma(mm, vb->baddr);
 156         if (!vma)
 157                 goto out_up;
 158
 159         if ((vb->baddr + mem->size) > vma->vm_end)
 160                 goto out_up;
 161
 162         pages_done = 0;
 163         prev_pfn = 0; /* kill warning */
 164         user_address = vb->baddr;
 165
 166         while (pages_done < (mem->size >> PAGE_SHIFT)) {
 167                 ret = follow_pfn(vma, user_address, &this_pfn);
 168                 if (ret)
 169                         break;
 170
 171                 if (pages_done == 0)
 172                         mem->dma_handle = (this_pfn << PAGE_SHIFT) + offset;
 173                 else if (this_pfn != (prev_pfn + 1))
 174                         ret = -EFAULT;
 175
 176                 if (ret)
 177                         break;
 178
 179                 prev_pfn = this_pfn;
 180                 user_address += PAGE_SIZE;
 181                 pages_done++;
 182         }
 183
 184         if (!ret)
 185                 mem->is_userptr = 1;
 186
 187  out_up:
 188         up_read(&current->mm->mmap_sem);
 189
 190         return ret;
 191 }
 192
 193 static struct videobuf_buffer *__videobuf_alloc(size_t size)
 194 {
 195         struct videobuf_dma_contig_memory *mem;
 196         struct videobuf_buffer *vb;
 197
 198         vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
 199         if (vb) {
 200                 mem = vb->priv = ((char *)vb) + size;
 201                 mem->magic = MAGIC_DC_MEM;
 202         }
 203
 204         return vb;
 205 }
 206
 207 static void *__videobuf_to_vaddr(struct videobuf_buffer *buf)
 208 {
 209         struct videobuf_dma_contig_memory *mem = buf->priv;
 210
 211         BUG_ON(!mem);
 212         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 213
 214         return mem->vaddr;
 215 }
 216
 217 static int __videobuf_iolock(struct videobuf_queue *q,
 218                              struct videobuf_buffer *vb,
 219                              struct v4l2_framebuffer *fbuf)
 220 {
 221         struct videobuf_dma_contig_memory *mem = vb->priv;
 222
 223         BUG_ON(!mem);
 224         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 225
 226         switch (vb->memory) {
 227         case V4L2_MEMORY_MMAP:
 228                 dev_dbg(q->dev, "%s memory method MMAP\n", __func__);
 229
 230                 /* All handling should be done by __videobuf_mmap_mapper() */
 231                 if (!mem->vaddr) {
 232                         dev_err(q->dev, "memory is not alloced/mmapped.\n");
 233                         return -EINVAL;
 234                 }
 235                 break;
 236         case V4L2_MEMORY_USERPTR:
 237                 dev_dbg(q->dev, "%s memory method USERPTR\n", __func__);
 238
 239                 /* handle pointer from user space */
 240                 if (vb->baddr)
 241                         return videobuf_dma_contig_user_get(mem, vb);
 242
 243                 /* allocate memory for the read() method */
 244                 mem->size = PAGE_ALIGN(vb->size);
 245                 mem->vaddr = dma_alloc_coherent(q->dev, mem->size,
 246                                                 &mem->dma_handle, GFP_KERNEL);
 247                 if (!mem->vaddr) {
 248                         dev_err(q->dev, "dma_alloc_coherent %ld failed\n",
 249                                          mem->size);
 250                         return -ENOMEM;
 251                 }
 252
 253                 dev_dbg(q->dev, "dma_alloc_coherent data is at %p (%ld)\n",
 254                         mem->vaddr, mem->size);
 255                 break;
 256         case V4L2_MEMORY_OVERLAY:
 257         default:
 258                 dev_dbg(q->dev, "%s memory method OVERLAY/unknown\n",
 259                         __func__);
 260                 return -EINVAL;
 261         }
 262
 263         return 0;
 264 }
 265
 266 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
 267                                   struct videobuf_buffer *buf,
 268                                   struct vm_area_struct *vma)
 269 {
 270         struct videobuf_dma_contig_memory *mem;
 271         struct videobuf_mapping *map;
 272         int retval;
 273         unsigned long size;
 274
 275         dev_dbg(q->dev, "%s\n", __func__);
 276
 277         /* create mapping + update buffer list */
 278         map = kzalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
 279         if (!map)
 280                 return -ENOMEM;
 281
 282         buf->map = map;
 283         map->start = vma->vm_start;
 284         map->end = vma->vm_end;
 285         map->q = q;
 286
 287         buf->baddr = vma->vm_start;
 288
 289         mem = buf->priv;
 290         BUG_ON(!mem);
 291         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 292
 293         mem->size = PAGE_ALIGN(buf->bsize);
 294         mem->vaddr = dma_alloc_coherent(q->dev, mem->size,
 295                                         &mem->dma_handle, GFP_KERNEL);
 296         if (!mem->vaddr) {
 297                 dev_err(q->dev, "dma_alloc_coherent size %ld failed\n",
 298                         mem->size);
 299                 goto error;
 300         }
 301         dev_dbg(q->dev, "dma_alloc_coherent data is at addr %p (size %ld)\n",
 302                 mem->vaddr, mem->size);
 303
 304         /* Try to remap memory */
 305
 306         size = vma->vm_end - vma->vm_start;
 307         size = (size < mem->size) ? size : mem->size;
 308
 309         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 310         retval = remap_pfn_range(vma, vma->vm_start,
 311                                  mem->dma_handle >> PAGE_SHIFT,
 312                                  size, vma->vm_page_prot);
 313         if (retval) {
 314                 dev_err(q->dev, "mmap: remap failed with error %d. ", retval);
 315                 dma_free_coherent(q->dev, mem->size,
 316                                   mem->vaddr, mem->dma_handle);
 317                 goto error;
 318         }
 319
 320         vma->vm_ops          = &videobuf_vm_ops;
 321         vma->vm_flags       |= VM_DONTEXPAND;
 322         vma->vm_private_data = map;
 323
 324         dev_dbg(q->dev, "mmap %p: q=%p %08lx-%08lx (%lx) pgoff %08lx buf %d\n",
 325                 map, q, vma->vm_start, vma->vm_end,
 326                 (long int)buf->bsize,
 327                 vma->vm_pgoff, buf->i);
 328
 329         videobuf_vm_open(vma);
 330
 331         return 0;
 332
 333 error:
 334         kfree(map);
 335         return -ENOMEM;
 336 }
 337
 338 static struct videobuf_qtype_ops qops = {
 339         .magic        = MAGIC_QTYPE_OPS,
 340
 341         .alloc        = __videobuf_alloc,
 342         .iolock       = __videobuf_iolock,
 343         .mmap_mapper  = __videobuf_mmap_mapper,
 344         .vaddr        = __videobuf_to_vaddr,
 345 };
 346
 347 void videobuf_queue_dma_contig_init(struct videobuf_queue *q,
 348                                     const struct videobuf_queue_ops *ops,
 349                                     struct device *dev,
 350                                     spinlock_t *irqlock,
 351                                     enum v4l2_buf_type type,
 352                                     enum v4l2_field field,
 353                                     unsigned int msize,
 354                                     void *priv)
 355 {
 356         videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
 357                                  priv, &qops);
 358 }
 359 EXPORT_SYMBOL_GPL(videobuf_queue_dma_contig_init);
 360
 361 dma_addr_t videobuf_to_dma_contig(struct videobuf_buffer *buf)
 362 {
 363         struct videobuf_dma_contig_memory *mem = buf->priv;
 364
 365         BUG_ON(!mem);
 366         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 367
 368         return mem->dma_handle;
 369 }
 370 EXPORT_SYMBOL_GPL(videobuf_to_dma_contig);
 371
 372 void videobuf_dma_contig_free(struct videobuf_queue *q,
 373                               struct videobuf_buffer *buf)
 374 {
 375         struct videobuf_dma_contig_memory *mem = buf->priv;
 376
 377         /* mmapped memory can't be freed here, otherwise mmapped region
 378            would be released, while still needed. In this case, the memory
 379            release should happen inside videobuf_vm_close().
 380            So, it should free memory only if the memory were allocated for
 381            read() operation.
 382          */
 383         if (buf->memory != V4L2_MEMORY_USERPTR)
 384                 return;
 385
 386         if (!mem)
 387                 return;
 388
 389         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 390
 391         /* handle user space pointer case */
 392         if (buf->baddr) {
 393                 videobuf_dma_contig_user_put(mem);
 394                 return;
 395         }
 396
 397         /* read() method */
 398         dma_free_coherent(q->dev, mem->size, mem->vaddr, mem->dma_handle);
 399         mem->vaddr = NULL;
 400 }
 401 EXPORT_SYMBOL_GPL(videobuf_dma_contig_free);
 402
 403 MODULE_DESCRIPTION("helper module to manage video4linux dma contig buffers");
 404 MODULE_AUTHOR("Magnus Damm");
 405 MODULE_LICENSE("GPL");