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  */
  37 struct 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;
  61 out_release:
  62         put_vaddr_frames(vec);
  63 out_destroy:
  64         frame_vector_destroy(vec);
  65         return ERR_PTR(ret);
  66 }
  67 EXPORT_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  */
  76 void vb2_destroy_framevec(struct frame_vector *vec)
  77 {
  78         put_vaddr_frames(vec);
  79         frame_vector_destroy(vec);
  80 }
  81 EXPORT_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  */
  90 static 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  */
 108 static 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  */
 123 const struct vm_operations_struct vb2_common_vm_ops = {
 124         .open = vb2_common_vm_open,
 125         .close = vb2_common_vm_close,
 126 };
 127 EXPORT_SYMBOL_GPL(vb2_common_vm_ops);
 128
 129 MODULE_DESCRIPTION("common memory handling routines for videobuf2");
 130 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
 131 MODULE_LICENSE("GPL");