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 */
vb2_create_framevec(unsigned long start,unsigned long length,bool write)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, 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 */
vb2_destroy_framevec(struct frame_vector * vec)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 */
vb2_common_vm_open(struct vm_area_struct * vma)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, refcount_read(h->refcount), vma->vm_start,
96 vma->vm_end);
97
98 refcount_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 */
vb2_common_vm_close(struct vm_area_struct * vma)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, refcount_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 mmapped
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");
132