1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
|
/*
* videobuf2-memops.c - generic memory handling routines for videobuf2
*
* Copyright (C) 2010 Samsung Electronics
*
* Author: Pawel Osciak <pawel@osciak.com>
* Marek Szyprowski <m.szyprowski@samsung.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation.
*/
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/dma-mapping.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/file.h>
#include <media/videobuf2-core.h>
#include <media/videobuf2-memops.h>
/**
* vb2_get_vma() - acquire and lock the virtual memory area
* @vma: given virtual memory area
*
* This function attempts to acquire an area mapped in the userspace for
* the duration of a hardware operation. The area is "locked" by performing
* the same set of operation that are done when process calls fork() and
* memory areas are duplicated.
*
* Returns a copy of a virtual memory region on success or NULL.
*/
struct vm_area_struct *vb2_get_vma(struct vm_area_struct *vma)
{
struct vm_area_struct *vma_copy;
vma_copy = kmalloc(sizeof(*vma_copy), GFP_KERNEL);
if (vma_copy == NULL)
return NULL;
if (vma->vm_ops && vma->vm_ops->open)
vma->vm_ops->open(vma);
if (vma->vm_file)
get_file(vma->vm_file);
memcpy(vma_copy, vma, sizeof(*vma));
vma_copy->vm_mm = NULL;
vma_copy->vm_next = NULL;
vma_copy->vm_prev = NULL;
return vma_copy;
}
EXPORT_SYMBOL_GPL(vb2_get_vma);
/**
* vb2_put_userptr() - release a userspace virtual memory area
* @vma: virtual memory region associated with the area to be released
*
* This function releases the previously acquired memory area after a hardware
* operation.
*/
void vb2_put_vma(struct vm_area_struct *vma)
{
if (!vma)
return;
if (vma->vm_ops && vma->vm_ops->close)
vma->vm_ops->close(vma);
if (vma->vm_file)
fput(vma->vm_file);
kfree(vma);
}
EXPORT_SYMBOL_GPL(vb2_put_vma);
/**
* vb2_get_contig_userptr() - lock physically contiguous userspace mapped memory
* @vaddr: starting virtual address of the area to be verified
* @size: size of the area
* @res_paddr: will return physical address for the given vaddr
* @res_vma: will return locked copy of struct vm_area for the given area
*
* This function will go through memory area of size @size mapped at @vaddr and
* verify that the underlying physical pages are contiguous. If they are
* contiguous the virtual memory area is locked and a @res_vma is filled with
* the copy and @res_pa set to the physical address of the buffer.
*
* Returns 0 on success.
*/
int vb2_get_contig_userptr(unsigned long vaddr, unsigned long size,
struct vm_area_struct **res_vma, dma_addr_t *res_pa)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
unsigned long offset, start, end;
unsigned long this_pfn, prev_pfn;
dma_addr_t pa = 0;
start = vaddr;
offset = start & ~PAGE_MASK;
end = start + size;
vma = find_vma(mm, start);
if (vma == NULL || vma->vm_end < end)
return -EFAULT;
for (prev_pfn = 0; start < end; start += PAGE_SIZE) {
int ret = follow_pfn(vma, start, &this_pfn);
if (ret)
return ret;
if (prev_pfn == 0)
pa = this_pfn << PAGE_SHIFT;
else if (this_pfn != prev_pfn + 1)
return -EFAULT;
prev_pfn = this_pfn;
}
/*
* Memory is contigous, lock vma and return to the caller
*/
*res_vma = vb2_get_vma(vma);
if (*res_vma == NULL)
return -ENOMEM;
*res_pa = pa + offset;
return 0;
}
EXPORT_SYMBOL_GPL(vb2_get_contig_userptr);
/**
* vb2_mmap_pfn_range() - map physical pages to userspace
* @vma: virtual memory region for the mapping
* @paddr: starting physical address of the memory to be mapped
* @size: size of the memory to be mapped
* @vm_ops: vm operations to be assigned to the created area
* @priv: private data to be associated with the area
*
* Returns 0 on success.
*/
int vb2_mmap_pfn_range(struct vm_area_struct *vma, unsigned long paddr,
unsigned long size,
const struct vm_operations_struct *vm_ops,
void *priv)
{
int ret;
size = min_t(unsigned long, vma->vm_end - vma->vm_start, size);
vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
ret = remap_pfn_range(vma, vma->vm_start, paddr >> PAGE_SHIFT,
size, vma->vm_page_prot);
if (ret) {
printk(KERN_ERR "Remapping memory failed, error: %d\n", ret);
return ret;
}
vma->vm_flags |= VM_DONTEXPAND | VM_RESERVED;
vma->vm_private_data = priv;
vma->vm_ops = vm_ops;
vma->vm_ops->open(vma);
pr_debug("%s: mapped paddr 0x%08lx at 0x%08lx, size %ld\n",
__func__, paddr, vma->vm_start, size);
return 0;
}
EXPORT_SYMBOL_GPL(vb2_mmap_pfn_range);
/**
* vb2_common_vm_open() - increase refcount of the vma
* @vma: virtual memory region for the mapping
*
* This function adds another user to the provided vma. It expects
* struct vb2_vmarea_handler pointer in vma->vm_private_data.
*/
static void vb2_common_vm_open(struct vm_area_struct *vma)
{
struct vb2_vmarea_handler *h = vma->vm_private_data;
pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n",
__func__, h, atomic_read(h->refcount), vma->vm_start,
vma->vm_end);
atomic_inc(h->refcount);
}
/**
* vb2_common_vm_close() - decrease refcount of the vma
* @vma: virtual memory region for the mapping
*
* This function releases the user from the provided vma. It expects
* struct vb2_vmarea_handler pointer in vma->vm_private_data.
*/
static void vb2_common_vm_close(struct vm_area_struct *vma)
{
struct vb2_vmarea_handler *h = vma->vm_private_data;
pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n",
__func__, h, atomic_read(h->refcount), vma->vm_start,
vma->vm_end);
h->put(h->arg);
}
/**
* vb2_common_vm_ops - common vm_ops used for tracking refcount of mmaped
* video buffers
*/
const struct vm_operations_struct vb2_common_vm_ops = {
.open = vb2_common_vm_open,
.close = vb2_common_vm_close,
};
EXPORT_SYMBOL_GPL(vb2_common_vm_ops);
MODULE_DESCRIPTION("common memory handling routines for videobuf2");
MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
MODULE_LICENSE("GPL");
|
