1 | /************************************************************************** |
2 | * |
3 | * Copyright 2010 Pauli Nieminen. |
4 | * All Rights Reserved. |
5 | * |
6 | * Permission is hereby granted, free of charge, to any person obtaining a |
7 | * copy of this software and associated documentation files (the |
8 | * "Software"), to deal in the Software without restriction, including |
9 | * without limitation the rights to use, copy, modify, merge, publish, |
10 | * distribute, sub license, and/or sell copies of the Software, and to |
11 | * permit persons to whom the Software is furnished to do so, subject to |
12 | * the following conditions: |
13 | * |
14 | * The above copyright notice and this permission notice (including the |
15 | * next paragraph) shall be included in all copies or substantial portions |
16 | * of the Software. |
17 | * |
18 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
19 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
20 | * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL |
21 | * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, |
22 | * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR |
23 | * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE |
24 | * USE OR OTHER DEALINGS IN THE SOFTWARE. |
25 | * |
26 | * |
27 | **************************************************************************/ |
28 | /* |
29 | * Multipart buffer for coping data which is larger than the page size. |
30 | * |
31 | * Authors: |
32 | * Pauli Nieminen <suokkos-at-gmail-dot-com> |
33 | */ |
34 | |
35 | #include <linux/export.h> |
36 | #include <drm/drm_buffer.h> |
37 | |
38 | /** |
39 | * Allocate the drm buffer object. |
40 | * |
41 | * buf: Pointer to a pointer where the object is stored. |
42 | * size: The number of bytes to allocate. |
43 | */ |
44 | int drm_buffer_alloc(struct drm_buffer **buf, int size) |
45 | { |
46 | int nr_pages = size / PAGE_SIZE + 1; |
47 | int idx; |
48 | |
49 | /* Allocating pointer table to end of structure makes drm_buffer |
50 | * variable sized */ |
51 | *buf = kzalloc(sizeof(struct drm_buffer) + nr_pages*sizeof(char *), |
52 | GFP_KERNEL); |
53 | |
54 | if (*buf == NULL) { |
55 | DRM_ERROR("Failed to allocate drm buffer object to hold" |
56 | " %d bytes in %d pages.\n" , |
57 | size, nr_pages); |
58 | return -ENOMEM; |
59 | } |
60 | |
61 | (*buf)->size = size; |
62 | |
63 | for (idx = 0; idx < nr_pages; ++idx) { |
64 | |
65 | (*buf)->data[idx] = |
66 | kmalloc(min(PAGE_SIZE, size - idx * PAGE_SIZE), |
67 | GFP_KERNEL); |
68 | |
69 | |
70 | if ((*buf)->data[idx] == NULL) { |
71 | DRM_ERROR("Failed to allocate %dth page for drm" |
72 | " buffer with %d bytes and %d pages.\n" , |
73 | idx + 1, size, nr_pages); |
74 | goto error_out; |
75 | } |
76 | |
77 | } |
78 | |
79 | return 0; |
80 | |
81 | error_out: |
82 | |
83 | /* Only last element can be null pointer so check for it first. */ |
84 | if ((*buf)->data[idx]) |
85 | kfree((*buf)->data[idx]); |
86 | |
87 | for (--idx; idx >= 0; --idx) |
88 | kfree((*buf)->data[idx]); |
89 | |
90 | kfree(*buf); |
91 | return -ENOMEM; |
92 | } |
93 | EXPORT_SYMBOL(drm_buffer_alloc); |
94 | |
95 | /** |
96 | * Copy the user data to the begin of the buffer and reset the processing |
97 | * iterator. |
98 | * |
99 | * user_data: A pointer the data that is copied to the buffer. |
100 | * size: The Number of bytes to copy. |
101 | */ |
102 | int drm_buffer_copy_from_user(struct drm_buffer *buf, |
103 | void __user *user_data, int size) |
104 | { |
105 | int nr_pages = size / PAGE_SIZE + 1; |
106 | int idx; |
107 | |
108 | if (size > buf->size) { |
109 | DRM_ERROR("Requesting to copy %d bytes to a drm buffer with" |
110 | " %d bytes space\n" , |
111 | size, buf->size); |
112 | return -EFAULT; |
113 | } |
114 | |
115 | for (idx = 0; idx < nr_pages; ++idx) { |
116 | |
117 | if (copy_from_user(buf->data[idx], |
118 | (const char *)user_data + idx * PAGE_SIZE, |
119 | min(PAGE_SIZE, size - idx * PAGE_SIZE))) { |
120 | DRM_ERROR("Failed to copy user data (%p) to drm buffer" |
121 | " (%p) %dth page.\n" , |
122 | user_data, buf, idx); |
123 | return -EFAULT; |
124 | |
125 | } |
126 | } |
127 | buf->iterator = 0; |
128 | return 0; |
129 | } |
130 | EXPORT_SYMBOL(drm_buffer_copy_from_user); |
131 | |
132 | /** |
133 | * Free the drm buffer object |
134 | */ |
135 | void drm_buffer_free(struct drm_buffer *buf) |
136 | { |
137 | |
138 | if (buf != NULL) { |
139 | |
140 | int nr_pages = buf->size / PAGE_SIZE + 1; |
141 | int idx; |
142 | for (idx = 0; idx < nr_pages; ++idx) |
143 | kfree(buf->data[idx]); |
144 | |
145 | kfree(buf); |
146 | } |
147 | } |
148 | EXPORT_SYMBOL(drm_buffer_free); |
149 | |
150 | /** |
151 | * Read an object from buffer that may be split to multiple parts. If object |
152 | * is not split function just returns the pointer to object in buffer. But in |
153 | * case of split object data is copied to given stack object that is suplied |
154 | * by caller. |
155 | * |
156 | * The processing location of the buffer is also advanced to the next byte |
157 | * after the object. |
158 | * |
159 | * objsize: The size of the objet in bytes. |
160 | * stack_obj: A pointer to a memory location where object can be copied. |
161 | */ |
162 | void *drm_buffer_read_object(struct drm_buffer *buf, |
163 | int objsize, void *stack_obj) |
164 | { |
165 | int idx = drm_buffer_index(buf); |
166 | int page = drm_buffer_page(buf); |
167 | void *obj = NULL; |
168 | |
169 | if (idx + objsize <= PAGE_SIZE) { |
170 | obj = &buf->data[page][idx]; |
171 | } else { |
172 | /* The object is split which forces copy to temporary object.*/ |
173 | int beginsz = PAGE_SIZE - idx; |
174 | memcpy(stack_obj, &buf->data[page][idx], beginsz); |
175 | |
176 | memcpy((char *)stack_obj + beginsz, &buf->data[page + 1][0], |
177 | objsize - beginsz); |
178 | |
179 | obj = stack_obj; |
180 | } |
181 | |
182 | drm_buffer_advance(buf, objsize); |
183 | return obj; |
184 | } |
185 | EXPORT_SYMBOL(drm_buffer_read_object); |
186 | |