LXR linux/drivers/media/common/videobuf2/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 *
  30 * This function allocates and fills in a vector with pfns corresponding to
  31 * virtual address range passed in arguments. If pfns have corresponding pages,
  32 * page references are also grabbed to pin pages in memory. The function
  33 * returns pointer to the vector on success and error pointer in case of
  34 * failure. Returned vector needs to be freed via vb2_destroy_pfnvec().
  35 */
  36struct frame_vector *vb2_create_framevec(unsigned long start,
  37                                         unsigned long length)
  38{
  39        int ret;
  40        unsigned long first, last;
  41        unsigned long nr;
  42        struct frame_vector *vec;
  43
  44        first = start >> PAGE_SHIFT;
  45        last = (start + length - 1) >> PAGE_SHIFT;
  46        nr = last - first + 1;
  47        vec = frame_vector_create(nr);
  48        if (!vec)
  49                return ERR_PTR(-ENOMEM);
  50        ret = get_vaddr_frames(start & PAGE_MASK, nr, vec);
  51        if (ret < 0)
  52                goto out_destroy;
  53        /* We accept only complete set of PFNs */
  54        if (ret != nr) {
  55                ret = -EFAULT;
  56                goto out_release;
  57        }
  58        return vec;
  59out_release:
  60        put_vaddr_frames(vec);
  61out_destroy:
  62        frame_vector_destroy(vec);
  63        return ERR_PTR(ret);
  64}
  65EXPORT_SYMBOL(vb2_create_framevec);
  66
  67/**
  68 * vb2_destroy_framevec() - release vector of mapped pfns
  69 * @vec:        vector of pfns / pages to release
  70 *
  71 * This releases references to all pages in the vector @vec (if corresponding
  72 * pfns are backed by pages) and frees the passed vector.
  73 */
  74void vb2_destroy_framevec(struct frame_vector *vec)
  75{
  76        put_vaddr_frames(vec);
  77        frame_vector_destroy(vec);
  78}
  79EXPORT_SYMBOL(vb2_destroy_framevec);
  80
  81/**
  82 * vb2_common_vm_open() - increase refcount of the vma
  83 * @vma:        virtual memory region for the mapping
  84 *
  85 * This function adds another user to the provided vma. It expects
  86 * struct vb2_vmarea_handler pointer in vma->vm_private_data.
  87 */
  88static void vb2_common_vm_open(struct vm_area_struct *vma)
  89{
  90        struct vb2_vmarea_handler *h = vma->vm_private_data;
  91
  92        pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n",
  93               __func__, h, refcount_read(h->refcount), vma->vm_start,
  94               vma->vm_end);
  95
  96        refcount_inc(h->refcount);
  97}
  98
  99/**
 100 * vb2_common_vm_close() - decrease refcount of the vma
 101 * @vma:        virtual memory region for the mapping
 102 *
 103 * This function releases the user from the provided vma. It expects
 104 * struct vb2_vmarea_handler pointer in vma->vm_private_data.
 105 */
 106static void vb2_common_vm_close(struct vm_area_struct *vma)
 107{
 108        struct vb2_vmarea_handler *h = vma->vm_private_data;
 109
 110        pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n",
 111               __func__, h, refcount_read(h->refcount), vma->vm_start,
 112               vma->vm_end);
 113
 114        h->put(h->arg);
 115}
 116
 117/*
 118 * vb2_common_vm_ops - common vm_ops used for tracking refcount of mmapped
 119 * video buffers
 120 */
 121const struct vm_operations_struct vb2_common_vm_ops = {
 122        .open = vb2_common_vm_open,
 123        .close = vb2_common_vm_close,
 124};
 125EXPORT_SYMBOL_GPL(vb2_common_vm_ops);
 126
 127MODULE_DESCRIPTION("common memory handling routines for videobuf2");
 128MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
 129MODULE_LICENSE("GPL");
 130