LXR linux/drivers/media/v4l2-core/videobuf2-memops.c

   1/*
   2 * videobuf2-memops.c - generic memory handling routines for videobuf2
   3 *
   4 * Copyright (C) 2010 Samsung Electronics
   5 *
   6 * Author: Pawel Osciak <pawel@osciak.com>
   7 *         Marek Szyprowski <m.szyprowski@samsung.com>
   8 *
   9 * This program is free software; you can redistribute it and/or modify
  10 * it under the terms of the GNU General Public License as published by
  11 * the Free Software Foundation.
  12 */
  13
  14#include <linux/slab.h>
  15#include <linux/module.h>
  16#include <linux/dma-mapping.h>
  17#include <linux/vmalloc.h>
  18#include <linux/mm.h>
  19#include <linux/sched.h>
  20#include <linux/file.h>
  21
  22#include <media/videobuf2-v4l2.h>
  23#include <media/videobuf2-memops.h>
  24
  25/**
  26 * vb2_create_framevec() - map virtual addresses to pfns
  27 * @start:      Virtual user address where we start mapping
  28 * @length:     Length of a range to map
  29 * @write:      Should we map for writing into the area
  30 *
  31 * This function allocates and fills in a vector with pfns corresponding to
  32 * virtual address range passed in arguments. If pfns have corresponding pages,
  33 * page references are also grabbed to pin pages in memory. The function
  34 * returns pointer to the vector on success and error pointer in case of
  35 * failure. Returned vector needs to be freed via vb2_destroy_pfnvec().
  36 */
  37struct frame_vector *vb2_create_framevec(unsigned long start,
  38                                         unsigned long length,
  39                                         bool write)
  40{
  41        int ret;
  42        unsigned long first, last;
  43        unsigned long nr;
  44        struct frame_vector *vec;
  45
  46        first = start >> PAGE_SHIFT;
  47        last = (start + length - 1) >> PAGE_SHIFT;
  48        nr = last - first + 1;
  49        vec = frame_vector_create(nr);
  50        if (!vec)
  51                return ERR_PTR(-ENOMEM);
  52        ret = get_vaddr_frames(start & PAGE_MASK, nr, write, true, vec);
  53        if (ret < 0)
  54                goto out_destroy;
  55        /* We accept only complete set of PFNs */
  56        if (ret != nr) {
  57                ret = -EFAULT;
  58                goto out_release;
  59        }
  60        return vec;
  61out_release:
  62        put_vaddr_frames(vec);
  63out_destroy:
  64        frame_vector_destroy(vec);
  65        return ERR_PTR(ret);
  66}
  67EXPORT_SYMBOL(vb2_create_framevec);
  68
  69/**
  70 * vb2_destroy_framevec() - release vector of mapped pfns
  71 * @vec:        vector of pfns / pages to release
  72 *
  73 * This releases references to all pages in the vector @vec (if corresponding
  74 * pfns are backed by pages) and frees the passed vector.
  75 */
  76void vb2_destroy_framevec(struct frame_vector *vec)
  77{
  78        put_vaddr_frames(vec);
  79        frame_vector_destroy(vec);
  80}
  81EXPORT_SYMBOL(vb2_destroy_framevec);
  82
  83/**
  84 * vb2_common_vm_open() - increase refcount of the vma
  85 * @vma:        virtual memory region for the mapping
  86 *
  87 * This function adds another user to the provided vma. It expects
  88 * struct vb2_vmarea_handler pointer in vma->vm_private_data.
  89 */
  90static void vb2_common_vm_open(struct vm_area_struct *vma)
  91{
  92        struct vb2_vmarea_handler *h = vma->vm_private_data;
  93
  94        pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n",
  95               __func__, h, atomic_read(h->refcount), vma->vm_start,
  96               vma->vm_end);
  97
  98        atomic_inc(h->refcount);
  99}
 100
 101/**
 102 * vb2_common_vm_close() - decrease refcount of the vma
 103 * @vma:        virtual memory region for the mapping
 104 *
 105 * This function releases the user from the provided vma. It expects
 106 * struct vb2_vmarea_handler pointer in vma->vm_private_data.
 107 */
 108static void vb2_common_vm_close(struct vm_area_struct *vma)
 109{
 110        struct vb2_vmarea_handler *h = vma->vm_private_data;
 111
 112        pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n",
 113               __func__, h, atomic_read(h->refcount), vma->vm_start,
 114               vma->vm_end);
 115
 116        h->put(h->arg);
 117}
 118
 119/**
 120 * vb2_common_vm_ops - common vm_ops used for tracking refcount of mmaped
 121 * video buffers
 122 */
 123const struct vm_operations_struct vb2_common_vm_ops = {
 124        .open = vb2_common_vm_open,
 125        .close = vb2_common_vm_close,
 126};
 127EXPORT_SYMBOL_GPL(vb2_common_vm_ops);
 128
 129MODULE_DESCRIPTION("common memory handling routines for videobuf2");
 130MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
 131MODULE_LICENSE("GPL");
 132