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 */
37struct 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;
61out_release:
62	put_vaddr_frames(vec);
63out_destroy:
64	frame_vector_destroy(vec);
65	return ERR_PTR(ret);
66}
67EXPORT_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 */
76void vb2_destroy_framevec(struct frame_vector *vec)
77{
78	put_vaddr_frames(vec);
79	frame_vector_destroy(vec);
80}
81EXPORT_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 */
90static 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 */
108static 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 */
123const struct vm_operations_struct vb2_common_vm_ops = {
124	.open = vb2_common_vm_open,
125	.close = vb2_common_vm_close,
126};
127EXPORT_SYMBOL_GPL(vb2_common_vm_ops);
128
129MODULE_DESCRIPTION("common memory handling routines for videobuf2");
130MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
131MODULE_LICENSE("GPL");
132