drivers/media/v4l2-core/videobuf-dma-contig.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * helper functions for physically contiguous capture buffers
   4  *
   5  * The functions support hardware lacking scatter gather support
   6  * (i.e. the buffers must be linear in physical memory)
   7  *
   8  * Copyright (c) 2008 Magnus Damm
   9  *
  10  * Based on videobuf-vmalloc.c,
  11  * (c) 2007 Mauro Carvalho Chehab, <mchehab@kernel.org>
  12  */
  13
  14 #include <linux/init.h>
  15 #include <linux/module.h>
  16 #include <linux/mm.h>
  17 #include <linux/pagemap.h>
  18 #include <linux/dma-mapping.h>
  19 #include <linux/sched.h>
  20 #include <linux/slab.h>
  21 #include <media/videobuf-dma-contig.h>
  22
  23 struct videobuf_dma_contig_memory {
  24         u32 magic;
  25         void *vaddr;
  26         dma_addr_t dma_handle;
  27         unsigned long size;
  28 };
  29
  30 #define MAGIC_DC_MEM 0x0733ac61
  31 #define MAGIC_CHECK(is, should)                                             \
  32         if (unlikely((is) != (should))) {                                   \
  33                 pr_err("magic mismatch: %x expected %x\n", (is), (should)); \
  34                 BUG();                                                      \
  35         }
  36
  37 static int __videobuf_dc_alloc(struct device *dev,
  38                                struct videobuf_dma_contig_memory *mem,
  39                                unsigned long size, gfp_t flags)
  40 {
  41         mem->size = size;
  42         mem->vaddr = dma_alloc_coherent(dev, mem->size,
  43                                         &mem->dma_handle, flags);
  44
  45         if (!mem->vaddr) {
  46                 dev_err(dev, "memory alloc size %ld failed\n", mem->size);
  47                 return -ENOMEM;
  48         }
  49
  50         dev_dbg(dev, "dma mapped data is at %p (%ld)\n", mem->vaddr, mem->size);
  51
  52         return 0;
  53 }
  54
  55 static void __videobuf_dc_free(struct device *dev,
  56                                struct videobuf_dma_contig_memory *mem)
  57 {
  58         dma_free_coherent(dev, mem->size, mem->vaddr, mem->dma_handle);
  59
  60         mem->vaddr = NULL;
  61 }
  62
  63 static void videobuf_vm_open(struct vm_area_struct *vma)
  64 {
  65         struct videobuf_mapping *map = vma->vm_private_data;
  66
  67         dev_dbg(map->q->dev, "vm_open %p [count=%u,vma=%08lx-%08lx]\n",
  68                 map, map->count, vma->vm_start, vma->vm_end);
  69
  70         map->count++;
  71 }
  72
  73 static void videobuf_vm_close(struct vm_area_struct *vma)
  74 {
  75         struct videobuf_mapping *map = vma->vm_private_data;
  76         struct videobuf_queue *q = map->q;
  77         int i;
  78
  79         dev_dbg(q->dev, "vm_close %p [count=%u,vma=%08lx-%08lx]\n",
  80                 map, map->count, vma->vm_start, vma->vm_end);
  81
  82         map->count--;
  83         if (0 == map->count) {
  84                 struct videobuf_dma_contig_memory *mem;
  85
  86                 dev_dbg(q->dev, "munmap %p q=%p\n", map, q);
  87                 videobuf_queue_lock(q);
  88
  89                 /* We need first to cancel streams, before unmapping */
  90                 if (q->streaming)
  91                         videobuf_queue_cancel(q);
  92
  93                 for (i = 0; i < VIDEO_MAX_FRAME; i++) {
  94                         if (NULL == q->bufs[i])
  95                                 continue;
  96
  97                         if (q->bufs[i]->map != map)
  98                                 continue;
  99
 100                         mem = q->bufs[i]->priv;
 101                         if (mem) {
 102                                 /* This callback is called only if kernel has
 103                                    allocated memory and this memory is mmapped.
 104                                    In this case, memory should be freed,
 105                                    in order to do memory unmap.
 106                                  */
 107
 108                                 MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 109
 110                                 /* vfree is not atomic - can't be
 111                                    called with IRQ's disabled
 112                                  */
 113                                 dev_dbg(q->dev, "buf[%d] freeing %p\n",
 114                                         i, mem->vaddr);
 115
 116                                 __videobuf_dc_free(q->dev, mem);
 117                                 mem->vaddr = NULL;
 118                         }
 119
 120                         q->bufs[i]->map = NULL;
 121                         q->bufs[i]->baddr = 0;
 122                 }
 123
 124                 kfree(map);
 125
 126                 videobuf_queue_unlock(q);
 127         }
 128 }
 129
 130 static const struct vm_operations_struct videobuf_vm_ops = {
 131         .open   = videobuf_vm_open,
 132         .close  = videobuf_vm_close,
 133 };
 134
 135 /**
 136  * videobuf_dma_contig_user_put() - reset pointer to user space buffer
 137  * @mem: per-buffer private videobuf-dma-contig data
 138  *
 139  * This function resets the user space pointer
 140  */
 141 static void videobuf_dma_contig_user_put(struct videobuf_dma_contig_memory *mem)
 142 {
 143         mem->dma_handle = 0;
 144         mem->size = 0;
 145 }
 146
 147 /**
 148  * videobuf_dma_contig_user_get() - setup user space memory pointer
 149  * @mem: per-buffer private videobuf-dma-contig data
 150  * @vb: video buffer to map
 151  *
 152  * This function validates and sets up a pointer to user space memory.
 153  * Only physically contiguous pfn-mapped memory is accepted.
 154  *
 155  * Returns 0 if successful.
 156  */
 157 static int videobuf_dma_contig_user_get(struct videobuf_dma_contig_memory *mem,
 158                                         struct videobuf_buffer *vb)
 159 {
 160         unsigned long untagged_baddr = untagged_addr(vb->baddr);
 161         struct mm_struct *mm = current->mm;
 162         struct vm_area_struct *vma;
 163         unsigned long prev_pfn, this_pfn;
 164         unsigned long pages_done, user_address;
 165         unsigned int offset;
 166         int ret;
 167
 168         offset = untagged_baddr & ~PAGE_MASK;
 169         mem->size = PAGE_ALIGN(vb->size + offset);
 170         ret = -EINVAL;
 171
 172         mmap_read_lock(mm);
 173
 174         vma = find_vma(mm, untagged_baddr);
 175         if (!vma)
 176                 goto out_up;
 177
 178         if ((untagged_baddr + mem->size) > vma->vm_end)
 179                 goto out_up;
 180
 181         pages_done = 0;
 182         prev_pfn = 0; /* kill warning */
 183         user_address = untagged_baddr;
 184
 185         while (pages_done < (mem->size >> PAGE_SHIFT)) {
 186                 ret = follow_pfn(vma, user_address, &this_pfn);
 187                 if (ret)
 188                         break;
 189
 190                 if (pages_done == 0)
 191                         mem->dma_handle = (this_pfn << PAGE_SHIFT) + offset;
 192                 else if (this_pfn != (prev_pfn + 1))
 193                         ret = -EFAULT;
 194
 195                 if (ret)
 196                         break;
 197
 198                 prev_pfn = this_pfn;
 199                 user_address += PAGE_SIZE;
 200                 pages_done++;
 201         }
 202
 203 out_up:
 204         mmap_read_unlock(current->mm);
 205
 206         return ret;
 207 }
 208
 209 static struct videobuf_buffer *__videobuf_alloc(size_t size)
 210 {
 211         struct videobuf_dma_contig_memory *mem;
 212         struct videobuf_buffer *vb;
 213
 214         vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
 215         if (vb) {
 216                 vb->priv = ((char *)vb) + size;
 217                 mem = vb->priv;
 218                 mem->magic = MAGIC_DC_MEM;
 219         }
 220
 221         return vb;
 222 }
 223
 224 static void *__videobuf_to_vaddr(struct videobuf_buffer *buf)
 225 {
 226         struct videobuf_dma_contig_memory *mem = buf->priv;
 227
 228         BUG_ON(!mem);
 229         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 230
 231         return mem->vaddr;
 232 }
 233
 234 static int __videobuf_iolock(struct videobuf_queue *q,
 235                              struct videobuf_buffer *vb,
 236                              struct v4l2_framebuffer *fbuf)
 237 {
 238         struct videobuf_dma_contig_memory *mem = vb->priv;
 239
 240         BUG_ON(!mem);
 241         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 242
 243         switch (vb->memory) {
 244         case V4L2_MEMORY_MMAP:
 245                 dev_dbg(q->dev, "%s memory method MMAP\n", __func__);
 246
 247                 /* All handling should be done by __videobuf_mmap_mapper() */
 248                 if (!mem->vaddr) {
 249                         dev_err(q->dev, "memory is not allocated/mmapped.\n");
 250                         return -EINVAL;
 251                 }
 252                 break;
 253         case V4L2_MEMORY_USERPTR:
 254                 dev_dbg(q->dev, "%s memory method USERPTR\n", __func__);
 255
 256                 /* handle pointer from user space */
 257                 if (vb->baddr)
 258                         return videobuf_dma_contig_user_get(mem, vb);
 259
 260                 /* allocate memory for the read() method */
 261                 if (__videobuf_dc_alloc(q->dev, mem, PAGE_ALIGN(vb->size),
 262                                         GFP_KERNEL))
 263                         return -ENOMEM;
 264                 break;
 265         case V4L2_MEMORY_OVERLAY:
 266         default:
 267                 dev_dbg(q->dev, "%s memory method OVERLAY/unknown\n", __func__);
 268                 return -EINVAL;
 269         }
 270
 271         return 0;
 272 }
 273
 274 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
 275                                   struct videobuf_buffer *buf,
 276                                   struct vm_area_struct *vma)
 277 {
 278         struct videobuf_dma_contig_memory *mem;
 279         struct videobuf_mapping *map;
 280         int retval;
 281
 282         dev_dbg(q->dev, "%s\n", __func__);
 283
 284         /* create mapping + update buffer list */
 285         map = kzalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
 286         if (!map)
 287                 return -ENOMEM;
 288
 289         buf->map = map;
 290         map->q = q;
 291
 292         buf->baddr = vma->vm_start;
 293
 294         mem = buf->priv;
 295         BUG_ON(!mem);
 296         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 297
 298         if (__videobuf_dc_alloc(q->dev, mem, PAGE_ALIGN(buf->bsize),
 299                                 GFP_KERNEL | __GFP_COMP))
 300                 goto error;
 301
 302         /* Try to remap memory */
 303         vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 304
 305         /* the "vm_pgoff" is just used in v4l2 to find the
 306          * corresponding buffer data structure which is allocated
 307          * earlier and it does not mean the offset from the physical
 308          * buffer start address as usual. So set it to 0 to pass
 309          * the sanity check in vm_iomap_memory().
 310          */
 311         vma->vm_pgoff = 0;
 312
 313         retval = vm_iomap_memory(vma, mem->dma_handle, mem->size);
 314         if (retval) {
 315                 dev_err(q->dev, "mmap: remap failed with error %d. ",
 316                         retval);
 317                 dma_free_coherent(q->dev, mem->size,
 318                                   mem->vaddr, mem->dma_handle);
 319                 goto error;
 320         }
 321
 322         vma->vm_ops = &videobuf_vm_ops;
 323         vma->vm_flags |= VM_DONTEXPAND;
 324         vma->vm_private_data = map;
 325
 326         dev_dbg(q->dev, "mmap %p: q=%p %08lx-%08lx (%lx) pgoff %08lx buf %d\n",
 327                 map, q, vma->vm_start, vma->vm_end,
 328                 (long int)buf->bsize, vma->vm_pgoff, buf->i);
 329
 330         videobuf_vm_open(vma);
 331
 332         return 0;
 333
 334 error:
 335         kfree(map);
 336         return -ENOMEM;
 337 }
 338
 339 static struct videobuf_qtype_ops qops = {
 340         .magic          = MAGIC_QTYPE_OPS,
 341         .alloc_vb       = __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                                     struct mutex *ext_lock)
 356 {
 357         videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
 358                                  priv, &qops, ext_lock);
 359 }
 360 EXPORT_SYMBOL_GPL(videobuf_queue_dma_contig_init);
 361
 362 dma_addr_t videobuf_to_dma_contig(struct videobuf_buffer *buf)
 363 {
 364         struct videobuf_dma_contig_memory *mem = buf->priv;
 365
 366         BUG_ON(!mem);
 367         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 368
 369         return mem->dma_handle;
 370 }
 371 EXPORT_SYMBOL_GPL(videobuf_to_dma_contig);
 372
 373 void videobuf_dma_contig_free(struct videobuf_queue *q,
 374                               struct videobuf_buffer *buf)
 375 {
 376         struct videobuf_dma_contig_memory *mem = buf->priv;
 377
 378         /* mmapped memory can't be freed here, otherwise mmapped region
 379            would be released, while still needed. In this case, the memory
 380            release should happen inside videobuf_vm_close().
 381            So, it should free memory only if the memory were allocated for
 382            read() operation.
 383          */
 384         if (buf->memory != V4L2_MEMORY_USERPTR)
 385                 return;
 386
 387         if (!mem)
 388                 return;
 389
 390         MAGIC_CHECK(mem->magic, MAGIC_DC_MEM);
 391
 392         /* handle user space pointer case */
 393         if (buf->baddr) {
 394                 videobuf_dma_contig_user_put(mem);
 395                 return;
 396         }
 397
 398         /* read() method */
 399         if (mem->vaddr) {
 400                 __videobuf_dc_free(q->dev, mem);
 401                 mem->vaddr = NULL;
 402         }
 403 }
 404 EXPORT_SYMBOL_GPL(videobuf_dma_contig_free);
 405
 406 MODULE_DESCRIPTION("helper module to manage video4linux dma contig buffers");
 407 MODULE_AUTHOR("Magnus Damm");
 408 MODULE_LICENSE("GPL");