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
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;
59 out_release:
60 put_vaddr_frames(vec);
61 out_destroy:
62 frame_vector_destroy(vec);
63 return ERR_PTR(ret);
64 }
65 EXPORT_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 */
vb2_destroy_framevec(struct frame_vector * vec)74 void vb2_destroy_framevec(struct frame_vector *vec)
75 {
76 put_vaddr_frames(vec);
77 frame_vector_destroy(vec);
78 }
79 EXPORT_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 */
vb2_common_vm_open(struct vm_area_struct * vma)88 static 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 */
vb2_common_vm_close(struct vm_area_struct * vma)106 static 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 */
121 const struct vm_operations_struct vb2_common_vm_ops = {
122 .open = vb2_common_vm_open,
123 .close = vb2_common_vm_close,
124 };
125 EXPORT_SYMBOL_GPL(vb2_common_vm_ops);
126
127 MODULE_DESCRIPTION("common memory handling routines for videobuf2");
128 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
129 MODULE_LICENSE("GPL");
130