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 */
vb2_create_framevec(unsigned long start,unsigned long length)36 struct 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 unsigned int flags = FOLL_FORCE | FOLL_WRITE;
44
45 first = start >> PAGE_SHIFT;
46 last = (start + length - 1) >> PAGE_SHIFT;
47 nr = last - first + 1;
48 vec = frame_vector_create(nr);
49 if (!vec)
50 return ERR_PTR(-ENOMEM);
51 ret = get_vaddr_frames(start & PAGE_MASK, nr, flags, vec);
52 if (ret < 0)
53 goto out_destroy;
54 /* We accept only complete set of PFNs */
55 if (ret != nr) {
56 ret = -EFAULT;
57 goto out_release;
58 }
59 return vec;
60 out_release:
61 put_vaddr_frames(vec);
62 out_destroy:
63 frame_vector_destroy(vec);
64 return ERR_PTR(ret);
65 }
66 EXPORT_SYMBOL(vb2_create_framevec);
67
68 /**
69 * vb2_destroy_framevec() - release vector of mapped pfns
70 * @vec: vector of pfns / pages to release
71 *
72 * This releases references to all pages in the vector @vec (if corresponding
73 * pfns are backed by pages) and frees the passed vector.
74 */
vb2_destroy_framevec(struct frame_vector * vec)75 void vb2_destroy_framevec(struct frame_vector *vec)
76 {
77 put_vaddr_frames(vec);
78 frame_vector_destroy(vec);
79 }
80 EXPORT_SYMBOL(vb2_destroy_framevec);
81
82 /**
83 * vb2_common_vm_open() - increase refcount of the vma
84 * @vma: virtual memory region for the mapping
85 *
86 * This function adds another user to the provided vma. It expects
87 * struct vb2_vmarea_handler pointer in vma->vm_private_data.
88 */
vb2_common_vm_open(struct vm_area_struct * vma)89 static void vb2_common_vm_open(struct vm_area_struct *vma)
90 {
91 struct vb2_vmarea_handler *h = vma->vm_private_data;
92
93 pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n",
94 __func__, h, refcount_read(h->refcount), vma->vm_start,
95 vma->vm_end);
96
97 refcount_inc(h->refcount);
98 }
99
100 /**
101 * vb2_common_vm_close() - decrease refcount of the vma
102 * @vma: virtual memory region for the mapping
103 *
104 * This function releases the user from the provided vma. It expects
105 * struct vb2_vmarea_handler pointer in vma->vm_private_data.
106 */
vb2_common_vm_close(struct vm_area_struct * vma)107 static void vb2_common_vm_close(struct vm_area_struct *vma)
108 {
109 struct vb2_vmarea_handler *h = vma->vm_private_data;
110
111 pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n",
112 __func__, h, refcount_read(h->refcount), vma->vm_start,
113 vma->vm_end);
114
115 h->put(h->arg);
116 }
117
118 /*
119 * vb2_common_vm_ops - common vm_ops used for tracking refcount of mmapped
120 * video buffers
121 */
122 const struct vm_operations_struct vb2_common_vm_ops = {
123 .open = vb2_common_vm_open,
124 .close = vb2_common_vm_close,
125 };
126 EXPORT_SYMBOL_GPL(vb2_common_vm_ops);
127
128 MODULE_DESCRIPTION("common memory handling routines for videobuf2");
129 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
130 MODULE_LICENSE("GPL");
131
