drivers/media/video/videobuf-vmalloc.c

   1 /*
   2  * helper functions for vmalloc video4linux capture buffers
   3  *
   4  * The functions expect the hardware being able to scatter gather
   5  * (i.e. the buffers are not linear in physical memory, but fragmented
   6  * into PAGE_SIZE chunks).  They also assume the driver does not need
   7  * to touch the video data.
   8  *
   9  * (c) 2007 Mauro Carvalho Chehab, <mchehab@infradead.org>
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2
  14  */
  15
  16 #include <linux/init.h>
  17 #include <linux/module.h>
  18 #include <linux/moduleparam.h>
  19 #include <linux/slab.h>
  20 #include <linux/interrupt.h>
  21
  22 #include <linux/pci.h>
  23 #include <linux/vmalloc.h>
  24 #include <linux/pagemap.h>
  25 #include <asm/page.h>
  26 #include <asm/pgtable.h>
  27
  28 #include <media/videobuf-vmalloc.h>
  29
  30 #define MAGIC_DMABUF   0x17760309
  31 #define MAGIC_VMAL_MEM 0x18221223
  32
  33 #define MAGIC_CHECK(is, should)                                         \
  34         if (unlikely((is) != (should))) {                               \
  35                 printk(KERN_ERR "magic mismatch: %x (expected %x)\n",   \
  36                                 is, should);                            \
  37                 BUG();                                                  \
  38         }
  39
  40 static int debug;
  41 module_param(debug, int, 0644);
  42
  43 MODULE_DESCRIPTION("helper module to manage video4linux vmalloc buffers");
  44 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@infradead.org>");
  45 MODULE_LICENSE("GPL");
  46
  47 #define dprintk(level, fmt, arg...)                                     \
  48         if (debug >= level)                                             \
  49                 printk(KERN_DEBUG "vbuf-vmalloc: " fmt , ## arg)
  50
  51
  52 /***************************************************************************/
  53
  54 static void videobuf_vm_open(struct vm_area_struct *vma)
  55 {
  56         struct videobuf_mapping *map = vma->vm_private_data;
  57
  58         dprintk(2, "vm_open %p [count=%u,vma=%08lx-%08lx]\n", map,
  59                 map->count, vma->vm_start, vma->vm_end);
  60
  61         map->count++;
  62 }
  63
  64 static void videobuf_vm_close(struct vm_area_struct *vma)
  65 {
  66         struct videobuf_mapping *map = vma->vm_private_data;
  67         struct videobuf_queue *q = map->q;
  68         int i;
  69
  70         dprintk(2, "vm_close %p [count=%u,vma=%08lx-%08lx]\n", map,
  71                 map->count, vma->vm_start, vma->vm_end);
  72
  73         map->count--;
  74         if (0 == map->count) {
  75                 struct videobuf_vmalloc_memory *mem;
  76
  77                 dprintk(1, "munmap %p q=%p\n", map, q);
  78                 mutex_lock(&q->vb_lock);
  79
  80                 /* We need first to cancel streams, before unmapping */
  81                 if (q->streaming)
  82                         videobuf_queue_cancel(q);
  83
  84                 for (i = 0; i < VIDEO_MAX_FRAME; i++) {
  85                         if (NULL == q->bufs[i])
  86                                 continue;
  87
  88                         if (q->bufs[i]->map != map)
  89                                 continue;
  90
  91                         mem = q->bufs[i]->priv;
  92                         if (mem) {
  93                                 /* This callback is called only if kernel has
  94                                    allocated memory and this memory is mmapped.
  95                                    In this case, memory should be freed,
  96                                    in order to do memory unmap.
  97                                  */
  98
  99                                 MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);
 100
 101                                 /* vfree is not atomic - can't be
 102                                    called with IRQ's disabled
 103                                  */
 104                                 dprintk(1, "%s: buf[%d] freeing (%p)\n",
 105                                         __func__, i, mem->vmalloc);
 106
 107                                 vfree(mem->vmalloc);
 108                                 mem->vmalloc = NULL;
 109                         }
 110
 111                         q->bufs[i]->map   = NULL;
 112                         q->bufs[i]->baddr = 0;
 113                 }
 114
 115                 kfree(map);
 116
 117                 mutex_unlock(&q->vb_lock);
 118         }
 119
 120         return;
 121 }
 122
 123 static const struct vm_operations_struct videobuf_vm_ops = {
 124         .open     = videobuf_vm_open,
 125         .close    = videobuf_vm_close,
 126 };
 127
 128 /* ---------------------------------------------------------------------
 129  * vmalloc handlers for the generic methods
 130  */
 131
 132 /* Allocated area consists on 3 parts:
 133         struct video_buffer
 134         struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
 135         struct videobuf_dma_sg_memory
 136  */
 137
 138 static struct videobuf_buffer *__videobuf_alloc(size_t size)
 139 {
 140         struct videobuf_vmalloc_memory *mem;
 141         struct videobuf_buffer *vb;
 142
 143         vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
 144         if (!vb)
 145                 return vb;
 146
 147         mem = vb->priv = ((char *)vb) + size;
 148         mem->magic = MAGIC_VMAL_MEM;
 149
 150         dprintk(1, "%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
 151                 __func__, vb, (long)sizeof(*vb), (long)size - sizeof(*vb),
 152                 mem, (long)sizeof(*mem));
 153
 154         return vb;
 155 }
 156
 157 static int __videobuf_iolock(struct videobuf_queue *q,
 158                              struct videobuf_buffer *vb,
 159                              struct v4l2_framebuffer *fbuf)
 160 {
 161         struct videobuf_vmalloc_memory *mem = vb->priv;
 162         int pages;
 163
 164         BUG_ON(!mem);
 165
 166         MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);
 167
 168         switch (vb->memory) {
 169         case V4L2_MEMORY_MMAP:
 170                 dprintk(1, "%s memory method MMAP\n", __func__);
 171
 172                 /* All handling should be done by __videobuf_mmap_mapper() */
 173                 if (!mem->vmalloc) {
 174                         printk(KERN_ERR "memory is not alloced/mmapped.\n");
 175                         return -EINVAL;
 176                 }
 177                 break;
 178         case V4L2_MEMORY_USERPTR:
 179                 pages = PAGE_ALIGN(vb->size);
 180
 181                 dprintk(1, "%s memory method USERPTR\n", __func__);
 182
 183                 if (vb->baddr) {
 184                         printk(KERN_ERR "USERPTR is currently not supported\n");
 185                         return -EINVAL;
 186                 }
 187
 188                 /* The only USERPTR currently supported is the one needed for
 189                  * read() method.
 190                  */
 191
 192                 mem->vmalloc = vmalloc_user(pages);
 193                 if (!mem->vmalloc) {
 194                         printk(KERN_ERR "vmalloc (%d pages) failed\n", pages);
 195                         return -ENOMEM;
 196                 }
 197                 dprintk(1, "vmalloc is at addr %p (%d pages)\n",
 198                         mem->vmalloc, pages);
 199
 200 #if 0
 201                 int rc;
 202                 /* Kernel userptr is used also by read() method. In this case,
 203                    there's no need to remap, since data will be copied to user
 204                  */
 205                 if (!vb->baddr)
 206                         return 0;
 207
 208                 /* FIXME: to properly support USERPTR, remap should occur.
 209                    The code below won't work, since mem->vma = NULL
 210                  */
 211                 /* Try to remap memory */
 212                 rc = remap_vmalloc_range(mem->vma, (void *)vb->baddr, 0);
 213                 if (rc < 0) {
 214                         printk(KERN_ERR "mmap: remap failed with error %d", rc);
 215                         return -ENOMEM;
 216                 }
 217 #endif
 218
 219                 break;
 220         case V4L2_MEMORY_OVERLAY:
 221         default:
 222                 dprintk(1, "%s memory method OVERLAY/unknown\n", __func__);
 223
 224                 /* Currently, doesn't support V4L2_MEMORY_OVERLAY */
 225                 printk(KERN_ERR "Memory method currently unsupported.\n");
 226                 return -EINVAL;
 227         }
 228
 229         return 0;
 230 }
 231
 232 static int __videobuf_sync(struct videobuf_queue *q,
 233                            struct videobuf_buffer *buf)
 234 {
 235         return 0;
 236 }
 237
 238 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
 239                                   struct videobuf_buffer *buf,
 240                                   struct vm_area_struct *vma)
 241 {
 242         struct videobuf_vmalloc_memory *mem;
 243         struct videobuf_mapping *map;
 244         int retval, pages;
 245
 246         dprintk(1, "%s\n", __func__);
 247
 248         /* create mapping + update buffer list */
 249         map = kzalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
 250         if (NULL == map)
 251                 return -ENOMEM;
 252
 253         buf->map = map;
 254         map->start = vma->vm_start;
 255         map->end   = vma->vm_end;
 256         map->q     = q;
 257
 258         buf->baddr = vma->vm_start;
 259
 260         mem = buf->priv;
 261         BUG_ON(!mem);
 262         MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);
 263
 264         pages = PAGE_ALIGN(vma->vm_end - vma->vm_start);
 265         mem->vmalloc = vmalloc_user(pages);
 266         if (!mem->vmalloc) {
 267                 printk(KERN_ERR "vmalloc (%d pages) failed\n", pages);
 268                 goto error;
 269         }
 270         dprintk(1, "vmalloc is at addr %p (%d pages)\n", mem->vmalloc, pages);
 271
 272         /* Try to remap memory */
 273         retval = remap_vmalloc_range(vma, mem->vmalloc, 0);
 274         if (retval < 0) {
 275                 printk(KERN_ERR "mmap: remap failed with error %d. ", retval);
 276                 vfree(mem->vmalloc);
 277                 goto error;
 278         }
 279
 280         vma->vm_ops          = &videobuf_vm_ops;
 281         vma->vm_flags       |= VM_DONTEXPAND | VM_RESERVED;
 282         vma->vm_private_data = map;
 283
 284         dprintk(1, "mmap %p: q=%p %08lx-%08lx (%lx) pgoff %08lx buf %d\n",
 285                 map, q, vma->vm_start, vma->vm_end,
 286                 (long int)buf->bsize,
 287                 vma->vm_pgoff, buf->i);
 288
 289         videobuf_vm_open(vma);
 290
 291         return 0;
 292
 293 error:
 294         mem = NULL;
 295         kfree(map);
 296         return -ENOMEM;
 297 }
 298
 299 static struct videobuf_qtype_ops qops = {
 300         .magic        = MAGIC_QTYPE_OPS,
 301
 302         .alloc        = __videobuf_alloc,
 303         .iolock       = __videobuf_iolock,
 304         .sync         = __videobuf_sync,
 305         .mmap_mapper  = __videobuf_mmap_mapper,
 306         .vaddr        = videobuf_to_vmalloc,
 307 };
 308
 309 void videobuf_queue_vmalloc_init(struct videobuf_queue *q,
 310                          const struct videobuf_queue_ops *ops,
 311                          struct device *dev,
 312                          spinlock_t *irqlock,
 313                          enum v4l2_buf_type type,
 314                          enum v4l2_field field,
 315                          unsigned int msize,
 316                          void *priv)
 317 {
 318         videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
 319                                  priv, &qops);
 320 }
 321 EXPORT_SYMBOL_GPL(videobuf_queue_vmalloc_init);
 322
 323 void *videobuf_to_vmalloc(struct videobuf_buffer *buf)
 324 {
 325         struct videobuf_vmalloc_memory *mem = buf->priv;
 326         BUG_ON(!mem);
 327         MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);
 328
 329         return mem->vmalloc;
 330 }
 331 EXPORT_SYMBOL_GPL(videobuf_to_vmalloc);
 332
 333 void videobuf_vmalloc_free(struct videobuf_buffer *buf)
 334 {
 335         struct videobuf_vmalloc_memory *mem = buf->priv;
 336
 337         /* mmapped memory can't be freed here, otherwise mmapped region
 338            would be released, while still needed. In this case, the memory
 339            release should happen inside videobuf_vm_close().
 340            So, it should free memory only if the memory were allocated for
 341            read() operation.
 342          */
 343         if ((buf->memory != V4L2_MEMORY_USERPTR) || buf->baddr)
 344                 return;
 345
 346         if (!mem)
 347                 return;
 348
 349         MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);
 350
 351         vfree(mem->vmalloc);
 352         mem->vmalloc = NULL;
 353
 354         return;
 355 }
 356 EXPORT_SYMBOL_GPL(videobuf_vmalloc_free);
 357