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_mmap_mapper(struct videobuf_queue *q,
 233                                   struct videobuf_buffer *buf,
 234                                   struct vm_area_struct *vma)
 235 {
 236         struct videobuf_vmalloc_memory *mem;
 237         struct videobuf_mapping *map;
 238         int retval, pages;
 239
 240         dprintk(1, "%s\n", __func__);
 241
 242         /* create mapping + update buffer list */
 243         map = kzalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
 244         if (NULL == map)
 245                 return -ENOMEM;
 246
 247         buf->map = map;
 248         map->start = vma->vm_start;
 249         map->end   = vma->vm_end;
 250         map->q     = q;
 251
 252         buf->baddr = vma->vm_start;
 253
 254         mem = buf->priv;
 255         BUG_ON(!mem);
 256         MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);
 257
 258         pages = PAGE_ALIGN(vma->vm_end - vma->vm_start);
 259         mem->vmalloc = vmalloc_user(pages);
 260         if (!mem->vmalloc) {
 261                 printk(KERN_ERR "vmalloc (%d pages) failed\n", pages);
 262                 goto error;
 263         }
 264         dprintk(1, "vmalloc is at addr %p (%d pages)\n", mem->vmalloc, pages);
 265
 266         /* Try to remap memory */
 267         retval = remap_vmalloc_range(vma, mem->vmalloc, 0);
 268         if (retval < 0) {
 269                 printk(KERN_ERR "mmap: remap failed with error %d. ", retval);
 270                 vfree(mem->vmalloc);
 271                 goto error;
 272         }
 273
 274         vma->vm_ops          = &videobuf_vm_ops;
 275         vma->vm_flags       |= VM_DONTEXPAND | VM_RESERVED;
 276         vma->vm_private_data = map;
 277
 278         dprintk(1, "mmap %p: q=%p %08lx-%08lx (%lx) pgoff %08lx buf %d\n",
 279                 map, q, vma->vm_start, vma->vm_end,
 280                 (long int)buf->bsize,
 281                 vma->vm_pgoff, buf->i);
 282
 283         videobuf_vm_open(vma);
 284
 285         return 0;
 286
 287 error:
 288         mem = NULL;
 289         kfree(map);
 290         return -ENOMEM;
 291 }
 292
 293 static struct videobuf_qtype_ops qops = {
 294         .magic        = MAGIC_QTYPE_OPS,
 295
 296         .alloc        = __videobuf_alloc,
 297         .iolock       = __videobuf_iolock,
 298         .mmap_mapper  = __videobuf_mmap_mapper,
 299         .vaddr        = videobuf_to_vmalloc,
 300 };
 301
 302 void videobuf_queue_vmalloc_init(struct videobuf_queue *q,
 303                          const struct videobuf_queue_ops *ops,
 304                          struct device *dev,
 305                          spinlock_t *irqlock,
 306                          enum v4l2_buf_type type,
 307                          enum v4l2_field field,
 308                          unsigned int msize,
 309                          void *priv)
 310 {
 311         videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
 312                                  priv, &qops);
 313 }
 314 EXPORT_SYMBOL_GPL(videobuf_queue_vmalloc_init);
 315
 316 void *videobuf_to_vmalloc(struct videobuf_buffer *buf)
 317 {
 318         struct videobuf_vmalloc_memory *mem = buf->priv;
 319         BUG_ON(!mem);
 320         MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);
 321
 322         return mem->vmalloc;
 323 }
 324 EXPORT_SYMBOL_GPL(videobuf_to_vmalloc);
 325
 326 void videobuf_vmalloc_free(struct videobuf_buffer *buf)
 327 {
 328         struct videobuf_vmalloc_memory *mem = buf->priv;
 329
 330         /* mmapped memory can't be freed here, otherwise mmapped region
 331            would be released, while still needed. In this case, the memory
 332            release should happen inside videobuf_vm_close().
 333            So, it should free memory only if the memory were allocated for
 334            read() operation.
 335          */
 336         if ((buf->memory != V4L2_MEMORY_USERPTR) || buf->baddr)
 337                 return;
 338
 339         if (!mem)
 340                 return;
 341
 342         MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);
 343
 344         vfree(mem->vmalloc);
 345         mem->vmalloc = NULL;
 346
 347         return;
 348 }
 349 EXPORT_SYMBOL_GPL(videobuf_vmalloc_free);
 350