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004cc378 MS |
1 | /* |
2 | * videobuf2-memops.c - generic memory handling routines for videobuf2 | |
3 | * | |
4 | * Copyright (C) 2010 Samsung Electronics | |
5 | * | |
6 | * Author: Pawel Osciak <p.osciak@samsung.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 | #include <linux/slab.h> | |
22 | ||
23 | #include <media/videobuf2-core.h> | |
24 | #include <media/videobuf2-memops.h> | |
25 | ||
26 | /** | |
27 | * vb2_get_vma() - acquire and lock the virtual memory area | |
28 | * @vma: given virtual memory area | |
29 | * | |
30 | * This function attempts to acquire an area mapped in the userspace for | |
31 | * the duration of a hardware operation. The area is "locked" by performing | |
32 | * the same set of operation that are done when process calls fork() and | |
33 | * memory areas are duplicated. | |
34 | * | |
35 | * Returns a copy of a virtual memory region on success or NULL. | |
36 | */ | |
37 | struct vm_area_struct *vb2_get_vma(struct vm_area_struct *vma) | |
38 | { | |
39 | struct vm_area_struct *vma_copy; | |
40 | ||
41 | vma_copy = kmalloc(sizeof(*vma_copy), GFP_KERNEL); | |
42 | if (vma_copy == NULL) | |
43 | return NULL; | |
44 | ||
45 | if (vma->vm_ops && vma->vm_ops->open) | |
46 | vma->vm_ops->open(vma); | |
47 | ||
48 | if (vma->vm_file) | |
49 | get_file(vma->vm_file); | |
50 | ||
51 | memcpy(vma_copy, vma, sizeof(*vma)); | |
52 | ||
53 | vma_copy->vm_mm = NULL; | |
54 | vma_copy->vm_next = NULL; | |
55 | vma_copy->vm_prev = NULL; | |
56 | ||
57 | return vma_copy; | |
58 | } | |
59 | ||
60 | /** | |
61 | * vb2_put_userptr() - release a userspace virtual memory area | |
62 | * @vma: virtual memory region associated with the area to be released | |
63 | * | |
64 | * This function releases the previously acquired memory area after a hardware | |
65 | * operation. | |
66 | */ | |
67 | void vb2_put_vma(struct vm_area_struct *vma) | |
68 | { | |
69 | if (!vma) | |
70 | return; | |
71 | ||
72 | if (vma->vm_file) | |
73 | fput(vma->vm_file); | |
74 | ||
75 | if (vma->vm_ops && vma->vm_ops->close) | |
76 | vma->vm_ops->close(vma); | |
77 | ||
78 | kfree(vma); | |
79 | } | |
80 | ||
81 | /** | |
82 | * vb2_get_contig_userptr() - lock physically contiguous userspace mapped memory | |
83 | * @vaddr: starting virtual address of the area to be verified | |
84 | * @size: size of the area | |
85 | * @res_paddr: will return physical address for the given vaddr | |
86 | * @res_vma: will return locked copy of struct vm_area for the given area | |
87 | * | |
88 | * This function will go through memory area of size @size mapped at @vaddr and | |
89 | * verify that the underlying physical pages are contiguous. If they are | |
90 | * contiguous the virtual memory area is locked and a @res_vma is filled with | |
91 | * the copy and @res_pa set to the physical address of the buffer. | |
92 | * | |
93 | * Returns 0 on success. | |
94 | */ | |
95 | int vb2_get_contig_userptr(unsigned long vaddr, unsigned long size, | |
96 | struct vm_area_struct **res_vma, dma_addr_t *res_pa) | |
97 | { | |
98 | struct mm_struct *mm = current->mm; | |
99 | struct vm_area_struct *vma; | |
100 | unsigned long offset, start, end; | |
101 | unsigned long this_pfn, prev_pfn; | |
102 | dma_addr_t pa = 0; | |
103 | int ret = -EFAULT; | |
104 | ||
105 | start = vaddr; | |
106 | offset = start & ~PAGE_MASK; | |
107 | end = start + size; | |
108 | ||
109 | down_read(&mm->mmap_sem); | |
110 | vma = find_vma(mm, start); | |
111 | ||
112 | if (vma == NULL || vma->vm_end < end) | |
113 | goto done; | |
114 | ||
115 | for (prev_pfn = 0; start < end; start += PAGE_SIZE) { | |
116 | ret = follow_pfn(vma, start, &this_pfn); | |
117 | if (ret) | |
118 | goto done; | |
119 | ||
120 | if (prev_pfn == 0) | |
121 | pa = this_pfn << PAGE_SHIFT; | |
122 | else if (this_pfn != prev_pfn + 1) { | |
123 | ret = -EFAULT; | |
124 | goto done; | |
125 | } | |
126 | prev_pfn = this_pfn; | |
127 | } | |
128 | ||
129 | /* | |
130 | * Memory is contigous, lock vma and return to the caller | |
131 | */ | |
132 | *res_vma = vb2_get_vma(vma); | |
133 | if (*res_vma == NULL) { | |
134 | ret = -ENOMEM; | |
135 | goto done; | |
136 | } | |
137 | *res_pa = pa + offset; | |
138 | ret = 0; | |
139 | ||
140 | done: | |
141 | up_read(&mm->mmap_sem); | |
142 | return ret; | |
143 | } | |
144 | ||
145 | /** | |
146 | * vb2_mmap_pfn_range() - map physical pages to userspace | |
147 | * @vma: virtual memory region for the mapping | |
148 | * @paddr: starting physical address of the memory to be mapped | |
149 | * @size: size of the memory to be mapped | |
150 | * @vm_ops: vm operations to be assigned to the created area | |
151 | * @priv: private data to be associated with the area | |
152 | * | |
153 | * Returns 0 on success. | |
154 | */ | |
155 | int vb2_mmap_pfn_range(struct vm_area_struct *vma, unsigned long paddr, | |
156 | unsigned long size, | |
157 | const struct vm_operations_struct *vm_ops, | |
158 | void *priv) | |
159 | { | |
160 | int ret; | |
161 | ||
162 | size = min_t(unsigned long, vma->vm_end - vma->vm_start, size); | |
163 | ||
164 | vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); | |
165 | ret = remap_pfn_range(vma, vma->vm_start, paddr >> PAGE_SHIFT, | |
166 | size, vma->vm_page_prot); | |
167 | if (ret) { | |
168 | printk(KERN_ERR "Remapping memory failed, error: %d\n", ret); | |
169 | return ret; | |
170 | } | |
171 | ||
172 | vma->vm_flags |= VM_DONTEXPAND | VM_RESERVED; | |
173 | vma->vm_private_data = priv; | |
174 | vma->vm_ops = vm_ops; | |
175 | ||
176 | vma->vm_ops->open(vma); | |
177 | ||
178 | printk(KERN_DEBUG "%s: mapped paddr 0x%08lx at 0x%08lx, size %ld\n", | |
179 | __func__, paddr, vma->vm_start, size); | |
180 | ||
181 | return 0; | |
182 | } | |
183 | ||
184 | /** | |
185 | * vb2_common_vm_open() - increase refcount of the vma | |
186 | * @vma: virtual memory region for the mapping | |
187 | * | |
188 | * This function adds another user to the provided vma. It expects | |
189 | * struct vb2_vmarea_handler pointer in vma->vm_private_data. | |
190 | */ | |
191 | static void vb2_common_vm_open(struct vm_area_struct *vma) | |
192 | { | |
193 | struct vb2_vmarea_handler *h = vma->vm_private_data; | |
194 | ||
195 | printk(KERN_DEBUG "%s: %p, refcount: %d, vma: %08lx-%08lx\n", | |
196 | __func__, h, atomic_read(h->refcount), vma->vm_start, | |
197 | vma->vm_end); | |
198 | ||
199 | atomic_inc(h->refcount); | |
200 | } | |
201 | ||
202 | /** | |
203 | * vb2_common_vm_close() - decrease refcount of the vma | |
204 | * @vma: virtual memory region for the mapping | |
205 | * | |
206 | * This function releases the user from the provided vma. It expects | |
207 | * struct vb2_vmarea_handler pointer in vma->vm_private_data. | |
208 | */ | |
209 | static void vb2_common_vm_close(struct vm_area_struct *vma) | |
210 | { | |
211 | struct vb2_vmarea_handler *h = vma->vm_private_data; | |
212 | ||
213 | printk(KERN_DEBUG "%s: %p, refcount: %d, vma: %08lx-%08lx\n", | |
214 | __func__, h, atomic_read(h->refcount), vma->vm_start, | |
215 | vma->vm_end); | |
216 | ||
217 | h->put(h->arg); | |
218 | } | |
219 | ||
220 | /** | |
221 | * vb2_common_vm_ops - common vm_ops used for tracking refcount of mmaped | |
222 | * video buffers | |
223 | */ | |
224 | const struct vm_operations_struct vb2_common_vm_ops = { | |
225 | .open = vb2_common_vm_open, | |
226 | .close = vb2_common_vm_close, | |
227 | }; | |
228 | EXPORT_SYMBOL_GPL(vb2_common_vm_ops); | |
229 | ||
230 | MODULE_DESCRIPTION("common memory handling routines for videobuf2"); | |
231 | MODULE_AUTHOR("Pawel Osciak"); | |
232 | MODULE_LICENSE("GPL"); |