Pileus Git - ~andy/linux/blob - drivers/media/v4l2-core/videobuf2-dma-contig.c

   1 /*
   2  * videobuf2-dma-contig.c - DMA contig memory allocator for videobuf2
   3  *
   4  * Copyright (C) 2010 Samsung Electronics
   5  *
   6  * Author: Pawel Osciak <pawel@osciak.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation.
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/scatterlist.h>
  15 #include <linux/sched.h>
  16 #include <linux/slab.h>
  17 #include <linux/dma-mapping.h>
  18
  19 #include <media/videobuf2-core.h>
  20 #include <media/videobuf2-dma-contig.h>
  21 #include <media/videobuf2-memops.h>
  22
  23 struct vb2_dc_conf {
  24         struct device           *dev;
  25 };
  26
  27 struct vb2_dc_buf {
  28         struct device                   *dev;
  29         void                            *vaddr;
  30         unsigned long                   size;
  31         dma_addr_t                      dma_addr;
  32         enum dma_data_direction         dma_dir;
  33         struct sg_table                 *dma_sgt;
  34
  35         /* MMAP related */
  36         struct vb2_vmarea_handler       handler;
  37         atomic_t                        refcount;
  38
  39         /* USERPTR related */
  40         struct vm_area_struct           *vma;
  41 };
  42
  43 /*********************************************/
  44 /*        scatterlist table functions        */
  45 /*********************************************/
  46
  47
  48 static void vb2_dc_sgt_foreach_page(struct sg_table *sgt,
  49         void (*cb)(struct page *pg))
  50 {
  51         struct scatterlist *s;
  52         unsigned int i;
  53
  54         for_each_sg(sgt->sgl, s, sgt->orig_nents, i) {
  55                 struct page *page = sg_page(s);
  56                 unsigned int n_pages = PAGE_ALIGN(s->offset + s->length)
  57                         >> PAGE_SHIFT;
  58                 unsigned int j;
  59
  60                 for (j = 0; j < n_pages; ++j, ++page)
  61                         cb(page);
  62         }
  63 }
  64
  65 static unsigned long vb2_dc_get_contiguous_size(struct sg_table *sgt)
  66 {
  67         struct scatterlist *s;
  68         dma_addr_t expected = sg_dma_address(sgt->sgl);
  69         unsigned int i;
  70         unsigned long size = 0;
  71
  72         for_each_sg(sgt->sgl, s, sgt->nents, i) {
  73                 if (sg_dma_address(s) != expected)
  74                         break;
  75                 expected = sg_dma_address(s) + sg_dma_len(s);
  76                 size += sg_dma_len(s);
  77         }
  78         return size;
  79 }
  80
  81 /*********************************************/
  82 /*         callbacks for all buffers         */
  83 /*********************************************/
  84
  85 static void *vb2_dc_cookie(void *buf_priv)
  86 {
  87         struct vb2_dc_buf *buf = buf_priv;
  88
  89         return &buf->dma_addr;
  90 }
  91
  92 static void *vb2_dc_vaddr(void *buf_priv)
  93 {
  94         struct vb2_dc_buf *buf = buf_priv;
  95
  96         return buf->vaddr;
  97 }
  98
  99 static unsigned int vb2_dc_num_users(void *buf_priv)
 100 {
 101         struct vb2_dc_buf *buf = buf_priv;
 102
 103         return atomic_read(&buf->refcount);
 104 }
 105
 106 static void vb2_dc_prepare(void *buf_priv)
 107 {
 108         struct vb2_dc_buf *buf = buf_priv;
 109         struct sg_table *sgt = buf->dma_sgt;
 110
 111         if (!sgt)
 112                 return;
 113
 114         dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 115 }
 116
 117 static void vb2_dc_finish(void *buf_priv)
 118 {
 119         struct vb2_dc_buf *buf = buf_priv;
 120         struct sg_table *sgt = buf->dma_sgt;
 121
 122         if (!sgt)
 123                 return;
 124
 125         dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->nents, buf->dma_dir);
 126 }
 127
 128 /*********************************************/
 129 /*        callbacks for MMAP buffers         */
 130 /*********************************************/
 131
 132 static void vb2_dc_put(void *buf_priv)
 133 {
 134         struct vb2_dc_buf *buf = buf_priv;
 135
 136         if (!atomic_dec_and_test(&buf->refcount))
 137                 return;
 138
 139         dma_free_coherent(buf->dev, buf->size, buf->vaddr, buf->dma_addr);
 140         kfree(buf);
 141 }
 142
 143 static void *vb2_dc_alloc(void *alloc_ctx, unsigned long size)
 144 {
 145         struct vb2_dc_conf *conf = alloc_ctx;
 146         struct device *dev = conf->dev;
 147         struct vb2_dc_buf *buf;
 148
 149         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 150         if (!buf)
 151                 return ERR_PTR(-ENOMEM);
 152
 153         buf->vaddr = dma_alloc_coherent(dev, size, &buf->dma_addr, GFP_KERNEL);
 154         if (!buf->vaddr) {
 155                 dev_err(dev, "dma_alloc_coherent of size %ld failed\n", size);
 156                 kfree(buf);
 157                 return ERR_PTR(-ENOMEM);
 158         }
 159
 160         buf->dev = dev;
 161         buf->size = size;
 162
 163         buf->handler.refcount = &buf->refcount;
 164         buf->handler.put = vb2_dc_put;
 165         buf->handler.arg = buf;
 166
 167         atomic_inc(&buf->refcount);
 168
 169         return buf;
 170 }
 171
 172 static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma)
 173 {
 174         struct vb2_dc_buf *buf = buf_priv;
 175
 176         if (!buf) {
 177                 printk(KERN_ERR "No buffer to map\n");
 178                 return -EINVAL;
 179         }
 180
 181         return vb2_mmap_pfn_range(vma, buf->dma_addr, buf->size,
 182                                   &vb2_common_vm_ops, &buf->handler);
 183 }
 184
 185 /*********************************************/
 186 /*       callbacks for USERPTR buffers       */
 187 /*********************************************/
 188
 189 static inline int vma_is_io(struct vm_area_struct *vma)
 190 {
 191         return !!(vma->vm_flags & (VM_IO | VM_PFNMAP));
 192 }
 193
 194 static int vb2_dc_get_user_pages(unsigned long start, struct page **pages,
 195         int n_pages, struct vm_area_struct *vma, int write)
 196 {
 197         if (vma_is_io(vma)) {
 198                 unsigned int i;
 199
 200                 for (i = 0; i < n_pages; ++i, start += PAGE_SIZE) {
 201                         unsigned long pfn;
 202                         int ret = follow_pfn(vma, start, &pfn);
 203
 204                         if (ret) {
 205                                 pr_err("no page for address %lu\n", start);
 206                                 return ret;
 207                         }
 208                         pages[i] = pfn_to_page(pfn);
 209                 }
 210         } else {
 211                 int n;
 212
 213                 n = get_user_pages(current, current->mm, start & PAGE_MASK,
 214                         n_pages, write, 1, pages, NULL);
 215                 /* negative error means that no page was pinned */
 216                 n = max(n, 0);
 217                 if (n != n_pages) {
 218                         pr_err("got only %d of %d user pages\n", n, n_pages);
 219                         while (n)
 220                                 put_page(pages[--n]);
 221                         return -EFAULT;
 222                 }
 223         }
 224
 225         return 0;
 226 }
 227
 228 static void vb2_dc_put_dirty_page(struct page *page)
 229 {
 230         set_page_dirty_lock(page);
 231         put_page(page);
 232 }
 233
 234 static void vb2_dc_put_userptr(void *buf_priv)
 235 {
 236         struct vb2_dc_buf *buf = buf_priv;
 237         struct sg_table *sgt = buf->dma_sgt;
 238
 239         dma_unmap_sg(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
 240         if (!vma_is_io(buf->vma))
 241                 vb2_dc_sgt_foreach_page(sgt, vb2_dc_put_dirty_page);
 242
 243         sg_free_table(sgt);
 244         kfree(sgt);
 245         vb2_put_vma(buf->vma);
 246         kfree(buf);
 247 }
 248
 249 static void *vb2_dc_get_userptr(void *alloc_ctx, unsigned long vaddr,
 250         unsigned long size, int write)
 251 {
 252         struct vb2_dc_conf *conf = alloc_ctx;
 253         struct vb2_dc_buf *buf;
 254         unsigned long start;
 255         unsigned long end;
 256         unsigned long offset;
 257         struct page **pages;
 258         int n_pages;
 259         int ret = 0;
 260         struct vm_area_struct *vma;
 261         struct sg_table *sgt;
 262         unsigned long contig_size;
 263
 264         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 265         if (!buf)
 266                 return ERR_PTR(-ENOMEM);
 267
 268         buf->dev = conf->dev;
 269         buf->dma_dir = write ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
 270
 271         start = vaddr & PAGE_MASK;
 272         offset = vaddr & ~PAGE_MASK;
 273         end = PAGE_ALIGN(vaddr + size);
 274         n_pages = (end - start) >> PAGE_SHIFT;
 275
 276         pages = kmalloc(n_pages * sizeof(pages[0]), GFP_KERNEL);
 277         if (!pages) {
 278                 ret = -ENOMEM;
 279                 pr_err("failed to allocate pages table\n");
 280                 goto fail_buf;
 281         }
 282
 283         /* current->mm->mmap_sem is taken by videobuf2 core */
 284         vma = find_vma(current->mm, vaddr);
 285         if (!vma) {
 286                 pr_err("no vma for address %lu\n", vaddr);
 287                 ret = -EFAULT;
 288                 goto fail_pages;
 289         }
 290
 291         if (vma->vm_end < vaddr + size) {
 292                 pr_err("vma at %lu is too small for %lu bytes\n", vaddr, size);
 293                 ret = -EFAULT;
 294                 goto fail_pages;
 295         }
 296
 297         buf->vma = vb2_get_vma(vma);
 298         if (!buf->vma) {
 299                 pr_err("failed to copy vma\n");
 300                 ret = -ENOMEM;
 301                 goto fail_pages;
 302         }
 303
 304         /* extract page list from userspace mapping */
 305         ret = vb2_dc_get_user_pages(start, pages, n_pages, vma, write);
 306         if (ret) {
 307                 pr_err("failed to get user pages\n");
 308                 goto fail_vma;
 309         }
 310
 311         sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
 312         if (!sgt) {
 313                 pr_err("failed to allocate sg table\n");
 314                 ret = -ENOMEM;
 315                 goto fail_get_user_pages;
 316         }
 317
 318         ret = sg_alloc_table_from_pages(sgt, pages, n_pages,
 319                 offset, size, GFP_KERNEL);
 320         if (ret) {
 321                 pr_err("failed to initialize sg table\n");
 322                 goto fail_sgt;
 323         }
 324
 325         /* pages are no longer needed */
 326         kfree(pages);
 327         pages = NULL;
 328
 329         sgt->nents = dma_map_sg(buf->dev, sgt->sgl, sgt->orig_nents,
 330                 buf->dma_dir);
 331         if (sgt->nents <= 0) {
 332                 pr_err("failed to map scatterlist\n");
 333                 ret = -EIO;
 334                 goto fail_sgt_init;
 335         }
 336
 337         contig_size = vb2_dc_get_contiguous_size(sgt);
 338         if (contig_size < size) {
 339                 pr_err("contiguous mapping is too small %lu/%lu\n",
 340                         contig_size, size);
 341                 ret = -EFAULT;
 342                 goto fail_map_sg;
 343         }
 344
 345         buf->dma_addr = sg_dma_address(sgt->sgl);
 346         buf->size = size;
 347         buf->dma_sgt = sgt;
 348
 349         return buf;
 350
 351 fail_map_sg:
 352         dma_unmap_sg(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir);
 353
 354 fail_sgt_init:
 355         if (!vma_is_io(buf->vma))
 356                 vb2_dc_sgt_foreach_page(sgt, put_page);
 357         sg_free_table(sgt);
 358
 359 fail_sgt:
 360         kfree(sgt);
 361
 362 fail_get_user_pages:
 363         if (pages && !vma_is_io(buf->vma))
 364                 while (n_pages)
 365                         put_page(pages[--n_pages]);
 366
 367 fail_vma:
 368         vb2_put_vma(buf->vma);
 369
 370 fail_pages:
 371         kfree(pages); /* kfree is NULL-proof */
 372
 373 fail_buf:
 374         kfree(buf);
 375
 376         return ERR_PTR(ret);
 377 }
 378
 379 /*********************************************/
 380 /*       DMA CONTIG exported functions       */
 381 /*********************************************/
 382
 383 const struct vb2_mem_ops vb2_dma_contig_memops = {
 384         .alloc          = vb2_dc_alloc,
 385         .put            = vb2_dc_put,
 386         .cookie         = vb2_dc_cookie,
 387         .vaddr          = vb2_dc_vaddr,
 388         .mmap           = vb2_dc_mmap,
 389         .get_userptr    = vb2_dc_get_userptr,
 390         .put_userptr    = vb2_dc_put_userptr,
 391         .prepare        = vb2_dc_prepare,
 392         .finish         = vb2_dc_finish,
 393         .num_users      = vb2_dc_num_users,
 394 };
 395 EXPORT_SYMBOL_GPL(vb2_dma_contig_memops);
 396
 397 void *vb2_dma_contig_init_ctx(struct device *dev)
 398 {
 399         struct vb2_dc_conf *conf;
 400
 401         conf = kzalloc(sizeof *conf, GFP_KERNEL);
 402         if (!conf)
 403                 return ERR_PTR(-ENOMEM);
 404
 405         conf->dev = dev;
 406
 407         return conf;
 408 }
 409 EXPORT_SYMBOL_GPL(vb2_dma_contig_init_ctx);
 410
 411 void vb2_dma_contig_cleanup_ctx(void *alloc_ctx)
 412 {
 413         kfree(alloc_ctx);
 414 }
 415 EXPORT_SYMBOL_GPL(vb2_dma_contig_cleanup_ctx);
 416
 417 MODULE_DESCRIPTION("DMA-contig memory handling routines for videobuf2");
 418 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
 419 MODULE_LICENSE("GPL");