drivers/media/video/videobuf2-vmalloc.c

   1 /*
   2  * videobuf2-vmalloc.c - vmalloc 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/mm.h>
  15 #include <linux/slab.h>
  16 #include <linux/vmalloc.h>
  17
  18 #include <media/videobuf2-core.h>
  19 #include <media/videobuf2-memops.h>
  20
  21 struct vb2_vmalloc_buf {
  22         void                            *vaddr;
  23         unsigned long                   size;
  24         atomic_t                        refcount;
  25         struct vb2_vmarea_handler       handler;
  26 };
  27
  28 static void vb2_vmalloc_put(void *buf_priv);
  29
  30 static void *vb2_vmalloc_alloc(void *alloc_ctx, unsigned long size)
  31 {
  32         struct vb2_vmalloc_buf *buf;
  33
  34         buf = kzalloc(sizeof *buf, GFP_KERNEL);
  35         if (!buf)
  36                 return NULL;
  37
  38         buf->size = size;
  39         buf->vaddr = vmalloc_user(buf->size);
  40         buf->handler.refcount = &buf->refcount;
  41         buf->handler.put = vb2_vmalloc_put;
  42         buf->handler.arg = buf;
  43
  44         if (!buf->vaddr) {
  45                 printk(KERN_ERR "vmalloc of size %ld failed\n", buf->size);
  46                 kfree(buf);
  47                 return NULL;
  48         }
  49
  50         atomic_inc(&buf->refcount);
  51         printk(KERN_DEBUG "Allocated vmalloc buffer of size %ld at vaddr=%p\n",
  52                         buf->size, buf->vaddr);
  53
  54         return buf;
  55 }
  56
  57 static void vb2_vmalloc_put(void *buf_priv)
  58 {
  59         struct vb2_vmalloc_buf *buf = buf_priv;
  60
  61         if (atomic_dec_and_test(&buf->refcount)) {
  62                 printk(KERN_DEBUG "%s: Freeing vmalloc mem at vaddr=%p\n",
  63                         __func__, buf->vaddr);
  64                 vfree(buf->vaddr);
  65                 kfree(buf);
  66         }
  67 }
  68
  69 static void *vb2_vmalloc_vaddr(void *buf_priv)
  70 {
  71         struct vb2_vmalloc_buf *buf = buf_priv;
  72
  73         BUG_ON(!buf);
  74
  75         if (!buf->vaddr) {
  76                 printk(KERN_ERR "Address of an unallocated plane requested\n");
  77                 return NULL;
  78         }
  79
  80         return buf->vaddr;
  81 }
  82
  83 static unsigned int vb2_vmalloc_num_users(void *buf_priv)
  84 {
  85         struct vb2_vmalloc_buf *buf = buf_priv;
  86         return atomic_read(&buf->refcount);
  87 }
  88
  89 static int vb2_vmalloc_mmap(void *buf_priv, struct vm_area_struct *vma)
  90 {
  91         struct vb2_vmalloc_buf *buf = buf_priv;
  92         int ret;
  93
  94         if (!buf) {
  95                 printk(KERN_ERR "No memory to map\n");
  96                 return -EINVAL;
  97         }
  98
  99         ret = remap_vmalloc_range(vma, buf->vaddr, 0);
 100         if (ret) {
 101                 printk(KERN_ERR "Remapping vmalloc memory, error: %d\n", ret);
 102                 return ret;
 103         }
 104
 105         /*
 106          * Make sure that vm_areas for 2 buffers won't be merged together
 107          */
 108         vma->vm_flags           |= VM_DONTEXPAND;
 109
 110         /*
 111          * Use common vm_area operations to track buffer refcount.
 112          */
 113         vma->vm_private_data    = &buf->handler;
 114         vma->vm_ops             = &vb2_common_vm_ops;
 115
 116         vma->vm_ops->open(vma);
 117
 118         return 0;
 119 }
 120
 121 const struct vb2_mem_ops vb2_vmalloc_memops = {
 122         .alloc          = vb2_vmalloc_alloc,
 123         .put            = vb2_vmalloc_put,
 124         .vaddr          = vb2_vmalloc_vaddr,
 125         .mmap           = vb2_vmalloc_mmap,
 126         .num_users      = vb2_vmalloc_num_users,
 127 };
 128 EXPORT_SYMBOL_GPL(vb2_vmalloc_memops);
 129
 130 MODULE_DESCRIPTION("vmalloc memory handling routines for videobuf2");
 131 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
 132 MODULE_LICENSE("GPL");