drivers/media/video/videobuf2-dma-sg.c

   1 /*
   2  * videobuf2-dma-sg.c - dma scatter/gather memory allocator for videobuf2
   3  *
   4  * Copyright (C) 2010 Samsung Electronics
   5  *
   6  * Author: Andrzej Pietrasiewicz <andrzej.p@samsung.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/mm.h>
  15 #include <linux/scatterlist.h>
  16 #include <linux/sched.h>
  17 #include <linux/slab.h>
  18 #include <linux/vmalloc.h>
  19
  20 #include <media/videobuf2-core.h>
  21 #include <media/videobuf2-memops.h>
  22 #include <media/videobuf2-dma-sg.h>
  23
  24 struct vb2_dma_sg_buf {
  25         void                            *vaddr;
  26         struct page                     **pages;
  27         int                             write;
  28         int                             offset;
  29         struct vb2_dma_sg_desc          sg_desc;
  30         atomic_t                        refcount;
  31         struct vb2_vmarea_handler       handler;
  32 };
  33
  34 static void vb2_dma_sg_put(void *buf_priv);
  35
  36 static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size)
  37 {
  38         struct vb2_dma_sg_buf *buf;
  39         int i;
  40
  41         buf = kzalloc(sizeof *buf, GFP_KERNEL);
  42         if (!buf)
  43                 return NULL;
  44
  45         buf->vaddr = NULL;
  46         buf->write = 0;
  47         buf->offset = 0;
  48         buf->sg_desc.size = size;
  49         buf->sg_desc.num_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
  50
  51         buf->sg_desc.sglist = vmalloc(buf->sg_desc.num_pages *
  52                                       sizeof(*buf->sg_desc.sglist));
  53         if (!buf->sg_desc.sglist)
  54                 goto fail_sglist_alloc;
  55         memset(buf->sg_desc.sglist, 0, buf->sg_desc.num_pages *
  56                sizeof(*buf->sg_desc.sglist));
  57         sg_init_table(buf->sg_desc.sglist, buf->sg_desc.num_pages);
  58
  59         buf->pages = kzalloc(buf->sg_desc.num_pages * sizeof(struct page *),
  60                              GFP_KERNEL);
  61         if (!buf->pages)
  62                 goto fail_pages_array_alloc;
  63
  64         for (i = 0; i < buf->sg_desc.num_pages; ++i) {
  65                 buf->pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN);
  66                 if (NULL == buf->pages[i])
  67                         goto fail_pages_alloc;
  68                 sg_set_page(&buf->sg_desc.sglist[i],
  69                             buf->pages[i], PAGE_SIZE, 0);
  70         }
  71
  72         buf->handler.refcount = &buf->refcount;
  73         buf->handler.put = vb2_dma_sg_put;
  74         buf->handler.arg = buf;
  75
  76         atomic_inc(&buf->refcount);
  77
  78         printk(KERN_DEBUG "%s: Allocated buffer of %d pages\n",
  79                 __func__, buf->sg_desc.num_pages);
  80
  81         if (!buf->vaddr)
  82                 buf->vaddr = vm_map_ram(buf->pages,
  83                                         buf->sg_desc.num_pages,
  84                                         -1,
  85                                         PAGE_KERNEL);
  86         return buf;
  87
  88 fail_pages_alloc:
  89         while (--i >= 0)
  90                 __free_page(buf->pages[i]);
  91         kfree(buf->pages);
  92
  93 fail_pages_array_alloc:
  94         vfree(buf->sg_desc.sglist);
  95
  96 fail_sglist_alloc:
  97         kfree(buf);
  98         return NULL;
  99 }
 100
 101 static void vb2_dma_sg_put(void *buf_priv)
 102 {
 103         struct vb2_dma_sg_buf *buf = buf_priv;
 104         int i = buf->sg_desc.num_pages;
 105
 106         if (atomic_dec_and_test(&buf->refcount)) {
 107                 printk(KERN_DEBUG "%s: Freeing buffer of %d pages\n", __func__,
 108                         buf->sg_desc.num_pages);
 109                 if (buf->vaddr)
 110                         vm_unmap_ram(buf->vaddr, buf->sg_desc.num_pages);
 111                 vfree(buf->sg_desc.sglist);
 112                 while (--i >= 0)
 113                         __free_page(buf->pages[i]);
 114                 kfree(buf->pages);
 115                 kfree(buf);
 116         }
 117 }
 118
 119 static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
 120                                     unsigned long size, int write)
 121 {
 122         struct vb2_dma_sg_buf *buf;
 123         unsigned long first, last;
 124         int num_pages_from_user, i;
 125
 126         buf = kzalloc(sizeof *buf, GFP_KERNEL);
 127         if (!buf)
 128                 return NULL;
 129
 130         buf->vaddr = NULL;
 131         buf->write = write;
 132         buf->offset = vaddr & ~PAGE_MASK;
 133         buf->sg_desc.size = size;
 134
 135         first = (vaddr           & PAGE_MASK) >> PAGE_SHIFT;
 136         last  = ((vaddr + size - 1) & PAGE_MASK) >> PAGE_SHIFT;
 137         buf->sg_desc.num_pages = last - first + 1;
 138
 139         buf->sg_desc.sglist = vmalloc(
 140                 buf->sg_desc.num_pages * sizeof(*buf->sg_desc.sglist));
 141         if (!buf->sg_desc.sglist)
 142                 goto userptr_fail_sglist_alloc;
 143
 144         memset(buf->sg_desc.sglist, 0,
 145                 buf->sg_desc.num_pages * sizeof(*buf->sg_desc.sglist));
 146         sg_init_table(buf->sg_desc.sglist, buf->sg_desc.num_pages);
 147
 148         buf->pages = kzalloc(buf->sg_desc.num_pages * sizeof(struct page *),
 149                              GFP_KERNEL);
 150         if (!buf->pages)
 151                 goto userptr_fail_pages_array_alloc;
 152
 153         down_read(&current->mm->mmap_sem);
 154         num_pages_from_user = get_user_pages(current, current->mm,
 155                                              vaddr & PAGE_MASK,
 156                                              buf->sg_desc.num_pages,
 157                                              write,
 158                                              1, /* force */
 159                                              buf->pages,
 160                                              NULL);
 161         up_read(&current->mm->mmap_sem);
 162         if (num_pages_from_user != buf->sg_desc.num_pages)
 163                 goto userptr_fail_get_user_pages;
 164
 165         sg_set_page(&buf->sg_desc.sglist[0], buf->pages[0],
 166                     PAGE_SIZE - buf->offset, buf->offset);
 167         size -= PAGE_SIZE - buf->offset;
 168         for (i = 1; i < buf->sg_desc.num_pages; ++i) {
 169                 sg_set_page(&buf->sg_desc.sglist[i], buf->pages[i],
 170                             min_t(size_t, PAGE_SIZE, size), 0);
 171                 size -= min_t(size_t, PAGE_SIZE, size);
 172         }
 173         return buf;
 174
 175 userptr_fail_get_user_pages:
 176         printk(KERN_DEBUG "get_user_pages requested/got: %d/%d]\n",
 177                num_pages_from_user, buf->sg_desc.num_pages);
 178         while (--num_pages_from_user >= 0)
 179                 put_page(buf->pages[num_pages_from_user]);
 180         kfree(buf->pages);
 181
 182 userptr_fail_pages_array_alloc:
 183         vfree(buf->sg_desc.sglist);
 184
 185 userptr_fail_sglist_alloc:
 186         kfree(buf);
 187         return NULL;
 188 }
 189
 190 /*
 191  * @put_userptr: inform the allocator that a USERPTR buffer will no longer
 192  *               be used
 193  */
 194 static void vb2_dma_sg_put_userptr(void *buf_priv)
 195 {
 196         struct vb2_dma_sg_buf *buf = buf_priv;
 197         int i = buf->sg_desc.num_pages;
 198
 199         printk(KERN_DEBUG "%s: Releasing userspace buffer of %d pages\n",
 200                __func__, buf->sg_desc.num_pages);
 201         if (buf->vaddr)
 202                 vm_unmap_ram(buf->vaddr, buf->sg_desc.num_pages);
 203         while (--i >= 0) {
 204                 if (buf->write)
 205                         set_page_dirty_lock(buf->pages[i]);
 206                 put_page(buf->pages[i]);
 207         }
 208         vfree(buf->sg_desc.sglist);
 209         kfree(buf->pages);
 210         kfree(buf);
 211 }
 212
 213 static void *vb2_dma_sg_vaddr(void *buf_priv)
 214 {
 215         struct vb2_dma_sg_buf *buf = buf_priv;
 216
 217         BUG_ON(!buf);
 218
 219         if (!buf->vaddr)
 220                 buf->vaddr = vm_map_ram(buf->pages,
 221                                         buf->sg_desc.num_pages,
 222                                         -1,
 223                                         PAGE_KERNEL);
 224
 225         /* add offset in case userptr is not page-aligned */
 226         return buf->vaddr + buf->offset;
 227 }
 228
 229 static unsigned int vb2_dma_sg_num_users(void *buf_priv)
 230 {
 231         struct vb2_dma_sg_buf *buf = buf_priv;
 232
 233         return atomic_read(&buf->refcount);
 234 }
 235
 236 static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
 237 {
 238         struct vb2_dma_sg_buf *buf = buf_priv;
 239         unsigned long uaddr = vma->vm_start;
 240         unsigned long usize = vma->vm_end - vma->vm_start;
 241         int i = 0;
 242
 243         if (!buf) {
 244                 printk(KERN_ERR "No memory to map\n");
 245                 return -EINVAL;
 246         }
 247
 248         do {
 249                 int ret;
 250
 251                 ret = vm_insert_page(vma, uaddr, buf->pages[i++]);
 252                 if (ret) {
 253                         printk(KERN_ERR "Remapping memory, error: %d\n", ret);
 254                         return ret;
 255                 }
 256
 257                 uaddr += PAGE_SIZE;
 258                 usize -= PAGE_SIZE;
 259         } while (usize > 0);
 260
 261
 262         /*
 263          * Use common vm_area operations to track buffer refcount.
 264          */
 265         vma->vm_private_data    = &buf->handler;
 266         vma->vm_ops             = &vb2_common_vm_ops;
 267
 268         vma->vm_ops->open(vma);
 269
 270         return 0;
 271 }
 272
 273 static void *vb2_dma_sg_cookie(void *buf_priv)
 274 {
 275         struct vb2_dma_sg_buf *buf = buf_priv;
 276
 277         return &buf->sg_desc;
 278 }
 279
 280 const struct vb2_mem_ops vb2_dma_sg_memops = {
 281         .alloc          = vb2_dma_sg_alloc,
 282         .put            = vb2_dma_sg_put,
 283         .get_userptr    = vb2_dma_sg_get_userptr,
 284         .put_userptr    = vb2_dma_sg_put_userptr,
 285         .vaddr          = vb2_dma_sg_vaddr,
 286         .mmap           = vb2_dma_sg_mmap,
 287         .num_users      = vb2_dma_sg_num_users,
 288         .cookie         = vb2_dma_sg_cookie,
 289 };
 290 EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
 291
 292 MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
 293 MODULE_AUTHOR("Andrzej Pietrasiewicz");
 294 MODULE_LICENSE("GPL");