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