drivers/media/v4l2-core/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@kernel.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@kernel.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                 videobuf_queue_lock(q);
  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->vaddr);
 106
 107                                 vfree(mem->vaddr);
 108                                 mem->vaddr = NULL;
 109                         }
 110
 111                         q->bufs[i]->map   = NULL;
 112                         q->bufs[i]->baddr = 0;
 113                 }
 114
 115                 kfree(map);
 116
 117                 videobuf_queue_unlock(q);
 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_vb(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->vaddr) {
 174                         printk(KERN_ERR "memory is not allocated/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->vaddr = vmalloc_user(pages);
 193                 if (!mem->vaddr) {
 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->vaddr, pages);
 199                 break;
 200         case V4L2_MEMORY_OVERLAY:
 201         default:
 202                 dprintk(1, "%s memory method OVERLAY/unknown\n", __func__);
 203
 204                 /* Currently, doesn't support V4L2_MEMORY_OVERLAY */
 205                 printk(KERN_ERR "Memory method currently unsupported.\n");
 206                 return -EINVAL;
 207         }
 208
 209         return 0;
 210 }
 211
 212 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
 213                                   struct videobuf_buffer *buf,
 214                                   struct vm_area_struct *vma)
 215 {
 216         struct videobuf_vmalloc_memory *mem;
 217         struct videobuf_mapping *map;
 218         int retval, pages;
 219
 220         dprintk(1, "%s\n", __func__);
 221
 222         /* create mapping + update buffer list */
 223         map = kzalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
 224         if (NULL == map)
 225                 return -ENOMEM;
 226
 227         buf->map = map;
 228         map->q     = q;
 229
 230         buf->baddr = vma->vm_start;
 231
 232         mem = buf->priv;
 233         BUG_ON(!mem);
 234         MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);
 235
 236         pages = PAGE_ALIGN(vma->vm_end - vma->vm_start);
 237         mem->vaddr = vmalloc_user(pages);
 238         if (!mem->vaddr) {
 239                 printk(KERN_ERR "vmalloc (%d pages) failed\n", pages);
 240                 goto error;
 241         }
 242         dprintk(1, "vmalloc is at addr %p (%d pages)\n", mem->vaddr, pages);
 243
 244         /* Try to remap memory */
 245         retval = remap_vmalloc_range(vma, mem->vaddr, 0);
 246         if (retval < 0) {
 247                 printk(KERN_ERR "mmap: remap failed with error %d. ", retval);
 248                 vfree(mem->vaddr);
 249                 goto error;
 250         }
 251
 252         vma->vm_ops          = &videobuf_vm_ops;
 253         vma->vm_flags       |= VM_DONTEXPAND | VM_DONTDUMP;
 254         vma->vm_private_data = map;
 255
 256         dprintk(1, "mmap %p: q=%p %08lx-%08lx (%lx) pgoff %08lx buf %d\n",
 257                 map, q, vma->vm_start, vma->vm_end,
 258                 (long int)buf->bsize,
 259                 vma->vm_pgoff, buf->i);
 260
 261         videobuf_vm_open(vma);
 262
 263         return 0;
 264
 265 error:
 266         mem = NULL;
 267         kfree(map);
 268         return -ENOMEM;
 269 }
 270
 271 static struct videobuf_qtype_ops qops = {
 272         .magic        = MAGIC_QTYPE_OPS,
 273
 274         .alloc_vb     = __videobuf_alloc_vb,
 275         .iolock       = __videobuf_iolock,
 276         .mmap_mapper  = __videobuf_mmap_mapper,
 277         .vaddr        = videobuf_to_vmalloc,
 278 };
 279
 280 void videobuf_queue_vmalloc_init(struct videobuf_queue *q,
 281                          const struct videobuf_queue_ops *ops,
 282                          struct device *dev,
 283                          spinlock_t *irqlock,
 284                          enum v4l2_buf_type type,
 285                          enum v4l2_field field,
 286                          unsigned int msize,
 287                          void *priv,
 288                          struct mutex *ext_lock)
 289 {
 290         videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
 291                                  priv, &qops, ext_lock);
 292 }
 293 EXPORT_SYMBOL_GPL(videobuf_queue_vmalloc_init);
 294
 295 void *videobuf_to_vmalloc(struct videobuf_buffer *buf)
 296 {
 297         struct videobuf_vmalloc_memory *mem = buf->priv;
 298         BUG_ON(!mem);
 299         MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);
 300
 301         return mem->vaddr;
 302 }
 303 EXPORT_SYMBOL_GPL(videobuf_to_vmalloc);
 304
 305 void videobuf_vmalloc_free(struct videobuf_buffer *buf)
 306 {
 307         struct videobuf_vmalloc_memory *mem = buf->priv;
 308
 309         /* mmapped memory can't be freed here, otherwise mmapped region
 310            would be released, while still needed. In this case, the memory
 311            release should happen inside videobuf_vm_close().
 312            So, it should free memory only if the memory were allocated for
 313            read() operation.
 314          */
 315         if ((buf->memory != V4L2_MEMORY_USERPTR) || buf->baddr)
 316                 return;
 317
 318         if (!mem)
 319                 return;
 320
 321         MAGIC_CHECK(mem->magic, MAGIC_VMAL_MEM);
 322
 323         vfree(mem->vaddr);
 324         mem->vaddr = NULL;
 325
 326         return;
 327 }
 328 EXPORT_SYMBOL_GPL(videobuf_vmalloc_free);
 329