drivers/media/v4l2-core/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@kernel.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 };
  32
  33 #define MAGIC_DC_MEM 0x0733ac61
  34 #define MAGIC_CHECK(is, should)                                             \
  35         if (unlikely((is) != (should))) {                                   \
  36                 pr_err("magic mismatch: %x expected %x\n", (is), (should)); \
  37                 BUG();                                                      \
  38         }
  39
  40 static int __videobuf_dc_alloc(struct device *dev,
  41                                struct videobuf_dma_contig_memory *mem,
  42                                unsigned long size, gfp_t flags)
  43 {
  44         mem->size = size;
  45         mem->vaddr = dma_alloc_coherent(dev, mem->size,
  46                                         &mem->dma_handle, flags);
  47
  48         if (!mem->vaddr) {
  49                 dev_err(dev, "memory alloc size %ld failed\n", mem->size);
  50                 return -ENOMEM;
  51         }
  52
  53         dev_dbg(dev, "dma mapped data is at %p (%ld)\n", mem->vaddr, mem->size);
  54
  55         return 0;
  56 }
  57
  58 static void __videobuf_dc_free(struct device *dev,
  59                                struct videobuf_dma_contig_memory *mem)
  60 {
  61         dma_free_coherent(dev, mem->size, mem->vaddr, mem->dma_handle);
  62
  63         mem->vaddr = NULL;
  64 }
  65
  66 static void videobuf_vm_open(struct vm_area_struct *vma)
  67 {
  68         struct videobuf_mapping *map = vma->vm_private_data;
  69
  70         dev_dbg(map->q->dev, "vm_open %p [count=%u,vma=%08lx-%08lx]\n",
  71                 map, map->count, vma->vm_start, vma->vm_end);
  72
  73         map->count++;
  74 }
  75
  76 static void videobuf_vm_close(struct vm_area_struct *vma)
  77 {
  78         struct videobuf_mapping *map = vma->vm_private_data;
  79         struct videobuf_queue *q = map->q;
  80         int i;
  81
  82         dev_dbg(q->dev, "vm_close %p [count=%u,vma=%08lx-%08lx]\n",
  83                 map, map->count, vma->vm_start, vma->vm_end);
  84
  85         map->count--;
  86         if (0 == map->count) {
  87                 struct videobuf_dma_contig_memory *mem;
  88
  89                 dev_dbg(q->dev, "munmap %p q=%p\n", map, q);
  90                 videobuf_queue_lock(q);
  91
  92                 /* We need first to cancel streams, before unmapping */
  93                 if (q->streaming)
  94                         videobuf_queue_cancel(q);
  95
  96                 for (i = 0; i < VIDEO_MAX_FRAME; i++) {
  97                         if (NULL == q->bufs[i])
  98                                 continue;
  99
 100                         if (q->bufs[i]->map != map)
 101                                 continue;
 102
 103                         mem = q->bufs[i]->priv;
 104                         if (mem) {
 105                                 /* This callback is called only if kernel has
 106                                    allocated memory and this memory is mmapped.
 107                                    In this case, memory should be freed,
 108                                    in order to do memory unmap.
 109                                  */
 110
 111                                 MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 112
 113                                 /* vfree is not atomic - can't be
 114                                    called with IRQ's disabled
 115                                  */
 116                                 dev_dbg(q->dev, "buf[%d] freeing %p\n",
 117                                         i, mem->vaddr);
 118
 119                                 __videobuf_dc_free(q->dev, mem);
 120                                 mem->vaddr = NULL;
 121                         }
 122
 123                         q->bufs[i]->map = NULL;
 124                         q->bufs[i]->baddr = 0;
 125                 }
 126
 127                 kfree(map);
 128
 129                 videobuf_queue_unlock(q);
 130         }
 131 }
 132
 133 static const struct vm_operations_struct videobuf_vm_ops = {
 134         .open   = videobuf_vm_open,
 135         .close  = videobuf_vm_close,
 136 };
 137
 138 /**
 139  * videobuf_dma_contig_user_put() - reset pointer to user space buffer
 140  * @mem: per-buffer private videobuf-dma-contig data
 141  *
 142  * This function resets the user space pointer
 143  */
 144 static void videobuf_dma_contig_user_put(struct videobuf_dma_contig_memory *mem)
 145 {
 146         mem->dma_handle = 0;
 147         mem->size = 0;
 148 }
 149
 150 /**
 151  * videobuf_dma_contig_user_get() - setup user space memory pointer
 152  * @mem: per-buffer private videobuf-dma-contig data
 153  * @vb: video buffer to map
 154  *
 155  * This function validates and sets up a pointer to user space memory.
 156  * Only physically contiguous pfn-mapped memory is accepted.
 157  *
 158  * Returns 0 if successful.
 159  */
 160 static int videobuf_dma_contig_user_get(struct videobuf_dma_contig_memory *mem,
 161                                         struct videobuf_buffer *vb)
 162 {
 163         struct mm_struct *mm = current->mm;
 164         struct vm_area_struct *vma;
 165         unsigned long prev_pfn, this_pfn;
 166         unsigned long pages_done, user_address;
 167         unsigned int offset;
 168         int ret;
 169
 170         offset = vb->baddr & ~PAGE_MASK;
 171         mem->size = PAGE_ALIGN(vb->size + offset);
 172         ret = -EINVAL;
 173
 174         down_read(&mm->mmap_sem);
 175
 176         vma = find_vma(mm, vb->baddr);
 177         if (!vma)
 178                 goto out_up;
 179
 180         if ((vb->baddr + mem->size) > vma->vm_end)
 181                 goto out_up;
 182
 183         pages_done = 0;
 184         prev_pfn = 0; /* kill warning */
 185         user_address = vb->baddr;
 186
 187         while (pages_done < (mem->size >> PAGE_SHIFT)) {
 188                 ret = follow_pfn(vma, user_address, &this_pfn);
 189                 if (ret)
 190                         break;
 191
 192                 if (pages_done == 0)
 193                         mem->dma_handle = (this_pfn << PAGE_SHIFT) + offset;
 194                 else if (this_pfn != (prev_pfn + 1))
 195                         ret = -EFAULT;
 196
 197                 if (ret)
 198                         break;
 199
 200                 prev_pfn = this_pfn;
 201                 user_address += PAGE_SIZE;
 202                 pages_done++;
 203         }
 204
 205 out_up:
 206         up_read(&current->mm->mmap_sem);
 207
 208         return ret;
 209 }
 210
 211 static struct videobuf_buffer *__videobuf_alloc(size_t size)
 212 {
 213         struct videobuf_dma_contig_memory *mem;
 214         struct videobuf_buffer *vb;
 215
 216         vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
 217         if (vb) {
 218                 vb->priv = ((char *)vb) + size;
 219                 mem = vb->priv;
 220                 mem->magic = MAGIC_DC_MEM;
 221         }
 222
 223         return vb;
 224 }
 225
 226 static void *__videobuf_to_vaddr(struct videobuf_buffer *buf)
 227 {
 228         struct videobuf_dma_contig_memory *mem = buf->priv;
 229
 230         BUG_ON(!mem);
 231         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 232
 233         return mem->vaddr;
 234 }
 235
 236 static int __videobuf_iolock(struct videobuf_queue *q,
 237                              struct videobuf_buffer *vb,
 238                              struct v4l2_framebuffer *fbuf)
 239 {
 240         struct videobuf_dma_contig_memory *mem = vb->priv;
 241
 242         BUG_ON(!mem);
 243         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 244
 245         switch (vb->memory) {
 246         case V4L2_MEMORY_MMAP:
 247                 dev_dbg(q->dev, "%s memory method MMAP\n", __func__);
 248
 249                 /* All handling should be done by __videobuf_mmap_mapper() */
 250                 if (!mem->vaddr) {
 251                         dev_err(q->dev, "memory is not alloced/mmapped.\n");
 252                         return -EINVAL;
 253                 }
 254                 break;
 255         case V4L2_MEMORY_USERPTR:
 256                 dev_dbg(q->dev, "%s memory method USERPTR\n", __func__);
 257
 258                 /* handle pointer from user space */
 259                 if (vb->baddr)
 260                         return videobuf_dma_contig_user_get(mem, vb);
 261
 262                 /* allocate memory for the read() method */
 263                 if (__videobuf_dc_alloc(q->dev, mem, PAGE_ALIGN(vb->size),
 264                                         GFP_KERNEL))
 265                         return -ENOMEM;
 266                 break;
 267         case V4L2_MEMORY_OVERLAY:
 268         default:
 269                 dev_dbg(q->dev, "%s memory method OVERLAY/unknown\n", __func__);
 270                 return -EINVAL;
 271         }
 272
 273         return 0;
 274 }
 275
 276 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
 277                                   struct videobuf_buffer *buf,
 278                                   struct vm_area_struct *vma)
 279 {
 280         struct videobuf_dma_contig_memory *mem;
 281         struct videobuf_mapping *map;
 282         int retval;
 283         unsigned long size;
 284
 285         dev_dbg(q->dev, "%s\n", __func__);
 286
 287         /* create mapping + update buffer list */
 288         map = kzalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
 289         if (!map)
 290                 return -ENOMEM;
 291
 292         buf->map = map;
 293         map->q = q;
 294
 295         buf->baddr = vma->vm_start;
 296
 297         mem = buf->priv;
 298         BUG_ON(!mem);
 299         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 300
 301         if (__videobuf_dc_alloc(q->dev, mem, PAGE_ALIGN(buf->bsize),
 302                                 GFP_KERNEL | __GFP_COMP))
 303                 goto error;
 304
 305         /* Try to remap memory */
 306         size = vma->vm_end - vma->vm_start;
 307         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 308
 309         /* the "vm_pgoff" is just used in v4l2 to find the
 310          * corresponding buffer data structure which is allocated
 311          * earlier and it does not mean the offset from the physical
 312          * buffer start address as usual. So set it to 0 to pass
 313          * the sanity check in vm_iomap_memory().
 314          */
 315         vma->vm_pgoff = 0;
 316
 317         retval = vm_iomap_memory(vma, mem->dma_handle, size);
 318         if (retval) {
 319                 dev_err(q->dev, "mmap: remap failed with error %d. ",
 320                         retval);
 321                 dma_free_coherent(q->dev, mem->size,
 322                                   mem->vaddr, mem->dma_handle);
 323                 goto error;
 324         }
 325
 326         vma->vm_ops = &videobuf_vm_ops;
 327         vma->vm_flags |= VM_DONTEXPAND;
 328         vma->vm_private_data = map;
 329
 330         dev_dbg(q->dev, "mmap %p: q=%p %08lx-%08lx (%lx) pgoff %08lx buf %d\n",
 331                 map, q, vma->vm_start, vma->vm_end,
 332                 (long int)buf->bsize, vma->vm_pgoff, buf->i);
 333
 334         videobuf_vm_open(vma);
 335
 336         return 0;
 337
 338 error:
 339         kfree(map);
 340         return -ENOMEM;
 341 }
 342
 343 static struct videobuf_qtype_ops qops = {
 344         .magic          = MAGIC_QTYPE_OPS,
 345         .alloc_vb       = __videobuf_alloc,
 346         .iolock         = __videobuf_iolock,
 347         .mmap_mapper    = __videobuf_mmap_mapper,
 348         .vaddr          = __videobuf_to_vaddr,
 349 };
 350
 351 void videobuf_queue_dma_contig_init(struct videobuf_queue *q,
 352                                     const struct videobuf_queue_ops *ops,
 353                                     struct device *dev,
 354                                     spinlock_t *irqlock,
 355                                     enum v4l2_buf_type type,
 356                                     enum v4l2_field field,
 357                                     unsigned int msize,
 358                                     void *priv,
 359                                     struct mutex *ext_lock)
 360 {
 361         videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
 362                                  priv, &qops, ext_lock);
 363 }
 364 EXPORT_SYMBOL_GPL(videobuf_queue_dma_contig_init);
 365
 366 dma_addr_t videobuf_to_dma_contig(struct videobuf_buffer *buf)
 367 {
 368         struct videobuf_dma_contig_memory *mem = buf->priv;
 369
 370         BUG_ON(!mem);
 371         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 372
 373         return mem->dma_handle;
 374 }
 375 EXPORT_SYMBOL_GPL(videobuf_to_dma_contig);
 376
 377 void videobuf_dma_contig_free(struct videobuf_queue *q,
 378                               struct videobuf_buffer *buf)
 379 {
 380         struct videobuf_dma_contig_memory *mem = buf->priv;
 381
 382         /* mmapped memory can't be freed here, otherwise mmapped region
 383            would be released, while still needed. In this case, the memory
 384            release should happen inside videobuf_vm_close().
 385            So, it should free memory only if the memory were allocated for
 386            read() operation.
 387          */
 388         if (buf->memory != V4L2_MEMORY_USERPTR)
 389                 return;
 390
 391         if (!mem)
 392                 return;
 393
 394         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 395
 396         /* handle user space pointer case */
 397         if (buf->baddr) {
 398                 videobuf_dma_contig_user_put(mem);
 399                 return;
 400         }
 401
 402         /* read() method */
 403         if (mem->vaddr) {
 404                 __videobuf_dc_free(q->dev, mem);
 405                 mem->vaddr = NULL;
 406         }
 407 }
 408 EXPORT_SYMBOL_GPL(videobuf_dma_contig_free);
 409
 410 MODULE_DESCRIPTION("helper module to manage video4linux dma contig buffers");
 411 MODULE_AUTHOR("Magnus Damm");
 412 MODULE_LICENSE("GPL");