1 /*
2 * videobuf2-dma-sg.c - dma scatter/gather memory allocator for videobuf2
3 *
4 * Copyright (C) 2010 Samsung Electronics
5 *
6 * Author: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation.
11 */
12
13 #include <linux/module.h>
14 #include <linux/mm.h>
15 #include <linux/scatterlist.h>
16 #include <linux/sched.h>
17 #include <linux/slab.h>
18 #include <linux/vmalloc.h>
19
20 #include <media/videobuf2-core.h>
21 #include <media/videobuf2-memops.h>
22 #include <media/videobuf2-dma-sg.h>
23
24 struct vb2_dma_sg_buf {
25 void *vaddr;
26 struct page **pages;
27 int write;
28 int offset;
29 struct vb2_dma_sg_desc sg_desc;
30 atomic_t refcount;
31 struct vb2_vmarea_handler handler;
32 };
33
34 static void vb2_dma_sg_put(void *buf_priv);
35
vb2_dma_sg_alloc(void * alloc_ctx,unsigned long size)36 static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size)
37 {
38 struct vb2_dma_sg_buf *buf;
39 int i;
40
41 buf = kzalloc(sizeof *buf, GFP_KERNEL);
42 if (!buf)
43 return NULL;
44
45 buf->vaddr = NULL;
46 buf->write = 0;
47 buf->offset = 0;
48 buf->sg_desc.size = size;
49 buf->sg_desc.num_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
50
51 buf->sg_desc.sglist = vzalloc(buf->sg_desc.num_pages *
52 sizeof(*buf->sg_desc.sglist));
53 if (!buf->sg_desc.sglist)
54 goto fail_sglist_alloc;
55 sg_init_table(buf->sg_desc.sglist, buf->sg_desc.num_pages);
56
57 buf->pages = kzalloc(buf->sg_desc.num_pages * sizeof(struct page *),
58 GFP_KERNEL);
59 if (!buf->pages)
60 goto fail_pages_array_alloc;
61
62 for (i = 0; i < buf->sg_desc.num_pages; ++i) {
63 buf->pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN);
64 if (NULL == buf->pages[i])
65 goto fail_pages_alloc;
66 sg_set_page(&buf->sg_desc.sglist[i],
67 buf->pages[i], PAGE_SIZE, 0);
68 }
69
70 buf->handler.refcount = &buf->refcount;
71 buf->handler.put = vb2_dma_sg_put;
72 buf->handler.arg = buf;
73
74 atomic_inc(&buf->refcount);
75
76 printk(KERN_DEBUG "%s: Allocated buffer of %d pages\n",
77 __func__, buf->sg_desc.num_pages);
78 return buf;
79
80 fail_pages_alloc:
81 while (--i >= 0)
82 __free_page(buf->pages[i]);
83 kfree(buf->pages);
84
85 fail_pages_array_alloc:
86 vfree(buf->sg_desc.sglist);
87
88 fail_sglist_alloc:
89 kfree(buf);
90 return NULL;
91 }
92
vb2_dma_sg_put(void * buf_priv)93 static void vb2_dma_sg_put(void *buf_priv)
94 {
95 struct vb2_dma_sg_buf *buf = buf_priv;
96 int i = buf->sg_desc.num_pages;
97
98 if (atomic_dec_and_test(&buf->refcount)) {
99 printk(KERN_DEBUG "%s: Freeing buffer of %d pages\n", __func__,
100 buf->sg_desc.num_pages);
101 if (buf->vaddr)
102 vm_unmap_ram(buf->vaddr, buf->sg_desc.num_pages);
103 vfree(buf->sg_desc.sglist);
104 while (--i >= 0)
105 __free_page(buf->pages[i]);
106 kfree(buf->pages);
107 kfree(buf);
108 }
109 }
110
vb2_dma_sg_get_userptr(void * alloc_ctx,unsigned long vaddr,unsigned long size,int write)111 static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
112 unsigned long size, int write)
113 {
114 struct vb2_dma_sg_buf *buf;
115 unsigned long first, last;
116 int num_pages_from_user, i;
117
118 buf = kzalloc(sizeof *buf, GFP_KERNEL);
119 if (!buf)
120 return NULL;
121
122 buf->vaddr = NULL;
123 buf->write = write;
124 buf->offset = vaddr & ~PAGE_MASK;
125 buf->sg_desc.size = size;
126
127 first = (vaddr & PAGE_MASK) >> PAGE_SHIFT;
128 last = ((vaddr + size - 1) & PAGE_MASK) >> PAGE_SHIFT;
129 buf->sg_desc.num_pages = last - first + 1;
130
131 buf->sg_desc.sglist = vzalloc(
132 buf->sg_desc.num_pages * sizeof(*buf->sg_desc.sglist));
133 if (!buf->sg_desc.sglist)
134 goto userptr_fail_sglist_alloc;
135
136 sg_init_table(buf->sg_desc.sglist, buf->sg_desc.num_pages);
137
138 buf->pages = kzalloc(buf->sg_desc.num_pages * sizeof(struct page *),
139 GFP_KERNEL);
140 if (!buf->pages)
141 goto userptr_fail_pages_array_alloc;
142
143 num_pages_from_user = get_user_pages(current, current->mm,
144 vaddr & PAGE_MASK,
145 buf->sg_desc.num_pages,
146 write,
147 1, /* force */
148 buf->pages,
149 NULL);
150
151 if (num_pages_from_user != buf->sg_desc.num_pages)
152 goto userptr_fail_get_user_pages;
153
154 sg_set_page(&buf->sg_desc.sglist[0], buf->pages[0],
155 PAGE_SIZE - buf->offset, buf->offset);
156 size -= PAGE_SIZE - buf->offset;
157 for (i = 1; i < buf->sg_desc.num_pages; ++i) {
158 sg_set_page(&buf->sg_desc.sglist[i], buf->pages[i],
159 min_t(size_t, PAGE_SIZE, size), 0);
160 size -= min_t(size_t, PAGE_SIZE, size);
161 }
162 return buf;
163
164 userptr_fail_get_user_pages:
165 printk(KERN_DEBUG "get_user_pages requested/got: %d/%d]\n",
166 num_pages_from_user, buf->sg_desc.num_pages);
167 while (--num_pages_from_user >= 0)
168 put_page(buf->pages[num_pages_from_user]);
169 kfree(buf->pages);
170
171 userptr_fail_pages_array_alloc:
172 vfree(buf->sg_desc.sglist);
173
174 userptr_fail_sglist_alloc:
175 kfree(buf);
176 return NULL;
177 }
178
179 /*
180 * @put_userptr: inform the allocator that a USERPTR buffer will no longer
181 * be used
182 */
vb2_dma_sg_put_userptr(void * buf_priv)183 static void vb2_dma_sg_put_userptr(void *buf_priv)
184 {
185 struct vb2_dma_sg_buf *buf = buf_priv;
186 int i = buf->sg_desc.num_pages;
187
188 printk(KERN_DEBUG "%s: Releasing userspace buffer of %d pages\n",
189 __func__, buf->sg_desc.num_pages);
190 if (buf->vaddr)
191 vm_unmap_ram(buf->vaddr, buf->sg_desc.num_pages);
192 while (--i >= 0) {
193 if (buf->write)
194 set_page_dirty_lock(buf->pages[i]);
195 put_page(buf->pages[i]);
196 }
197 vfree(buf->sg_desc.sglist);
198 kfree(buf->pages);
199 kfree(buf);
200 }
201
vb2_dma_sg_vaddr(void * buf_priv)202 static void *vb2_dma_sg_vaddr(void *buf_priv)
203 {
204 struct vb2_dma_sg_buf *buf = buf_priv;
205
206 BUG_ON(!buf);
207
208 if (!buf->vaddr)
209 buf->vaddr = vm_map_ram(buf->pages,
210 buf->sg_desc.num_pages,
211 -1,
212 PAGE_KERNEL);
213
214 /* add offset in case userptr is not page-aligned */
215 return buf->vaddr + buf->offset;
216 }
217
vb2_dma_sg_num_users(void * buf_priv)218 static unsigned int vb2_dma_sg_num_users(void *buf_priv)
219 {
220 struct vb2_dma_sg_buf *buf = buf_priv;
221
222 return atomic_read(&buf->refcount);
223 }
224
vb2_dma_sg_mmap(void * buf_priv,struct vm_area_struct * vma)225 static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
226 {
227 struct vb2_dma_sg_buf *buf = buf_priv;
228 unsigned long uaddr = vma->vm_start;
229 unsigned long usize = vma->vm_end - vma->vm_start;
230 int i = 0;
231
232 if (!buf) {
233 printk(KERN_ERR "No memory to map\n");
234 return -EINVAL;
235 }
236
237 do {
238 int ret;
239
240 ret = vm_insert_page(vma, uaddr, buf->pages[i++]);
241 if (ret) {
242 printk(KERN_ERR "Remapping memory, error: %d\n", ret);
243 return ret;
244 }
245
246 uaddr += PAGE_SIZE;
247 usize -= PAGE_SIZE;
248 } while (usize > 0);
249
250
251 /*
252 * Use common vm_area operations to track buffer refcount.
253 */
254 vma->vm_private_data = &buf->handler;
255 vma->vm_ops = &vb2_common_vm_ops;
256
257 vma->vm_ops->open(vma);
258
259 return 0;
260 }
261
vb2_dma_sg_cookie(void * buf_priv)262 static void *vb2_dma_sg_cookie(void *buf_priv)
263 {
264 struct vb2_dma_sg_buf *buf = buf_priv;
265
266 return &buf->sg_desc;
267 }
268
269 const struct vb2_mem_ops vb2_dma_sg_memops = {
270 .alloc = vb2_dma_sg_alloc,
271 .put = vb2_dma_sg_put,
272 .get_userptr = vb2_dma_sg_get_userptr,
273 .put_userptr = vb2_dma_sg_put_userptr,
274 .vaddr = vb2_dma_sg_vaddr,
275 .mmap = vb2_dma_sg_mmap,
276 .num_users = vb2_dma_sg_num_users,
277 .cookie = vb2_dma_sg_cookie,
278 };
279 EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
280
281 MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
282 MODULE_AUTHOR("Andrzej Pietrasiewicz");
283 MODULE_LICENSE("GPL");
284