aboutsummaryrefslogtreecommitdiff
path: root/drivers/media/v4l2-core/videobuf2-dma-sg.c
blob: c779f210d2c623e9807ad7c41737813ed92d43ea (plain)
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
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
/*
 * videobuf2-dma-sg.c - dma scatter/gather memory allocator for videobuf2
 *
 * Copyright (C) 2010 Samsung Electronics
 *
 * Author: Andrzej Pietrasiewicz <andrzej.p@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/module.h>
#include <linux/mm.h>
#include <linux/scatterlist.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>

#include <media/videobuf2-core.h>
#include <media/videobuf2-memops.h>
#include <media/videobuf2-dma-sg.h>

static int debug;
module_param(debug, int, 0644);

#define dprintk(level, fmt, arg...)					\
	do {								\
		if (debug >= level)					\
			printk(KERN_DEBUG "vb2-dma-sg: " fmt, ## arg);	\
	} while (0)

struct vb2_dma_sg_buf {
	void				*vaddr;
	struct page			**pages;
	int				write;
	int				offset;
	struct sg_table			sg_table;
	size_t				size;
	unsigned int			num_pages;
	atomic_t			refcount;
	struct vb2_vmarea_handler	handler;
	struct vm_area_struct		*vma;
};

static void vb2_dma_sg_put(void *buf_priv);

static int vb2_dma_sg_alloc_compacted(struct vb2_dma_sg_buf *buf,
		gfp_t gfp_flags)
{
	unsigned int last_page = 0;
	int size = buf->size;

	while (size > 0) {
		struct page *pages;
		int order;
		int i;

		order = get_order(size);
		/* Dont over allocate*/
		if ((PAGE_SIZE << order) > size)
			order--;

		pages = NULL;
		while (!pages) {
			pages = alloc_pages(GFP_KERNEL | __GFP_ZERO |
					__GFP_NOWARN | gfp_flags, order);
			if (pages)
				break;

			if (order == 0) {
				while (last_page--)
					__free_page(buf->pages[last_page]);
				return -ENOMEM;
			}
			order--;
		}

		split_page(pages, order);
		for (i = 0; i < (1 << order); i++)
			buf->pages[last_page++] = &pages[i];

		size -= PAGE_SIZE << order;
	}

	return 0;
}

static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size, gfp_t gfp_flags)
{
	struct vb2_dma_sg_buf *buf;
	int ret;
	int num_pages;

	buf = kzalloc(sizeof *buf, GFP_KERNEL);
	if (!buf)
		return NULL;

	buf->vaddr = NULL;
	buf->write = 0;
	buf->offset = 0;
	buf->size = size;
	/* size is already page aligned */
	buf->num_pages = size >> PAGE_SHIFT;

	buf->pages = kzalloc(buf->num_pages * sizeof(struct page *),
			     GFP_KERNEL);
	if (!buf->pages)
		goto fail_pages_array_alloc;

	ret = vb2_dma_sg_alloc_compacted(buf, gfp_flags);
	if (ret)
		goto fail_pages_alloc;

	ret = sg_alloc_table_from_pages(&buf->sg_table, buf->pages,
			buf->num_pages, 0, size, gfp_flags);
	if (ret)
		goto fail_table_alloc;

	buf->handler.refcount = &buf->refcount;
	buf->handler.put = vb2_dma_sg_put;
	buf->handler.arg = buf;

	atomic_inc(&buf->refcount);

	dprintk(1, "%s: Allocated buffer of %d pages\n",
		__func__, buf->num_pages);
	return buf;

fail_table_alloc:
	num_pages = buf->num_pages;
	while (num_pages--)
		__free_page(buf->pages[num_pages]);
fail_pages_alloc:
	kfree(buf->pages);
fail_pages_array_alloc:
	kfree(buf);
	return NULL;
}

static void vb2_dma_sg_put(void *buf_priv)
{
	struct vb2_dma_sg_buf *buf = buf_priv;
	int i = buf->num_pages;

	if (atomic_dec_and_test(&buf->refcount)) {
		dprintk(1, "%s: Freeing buffer of %d pages\n", __func__,
			buf->num_pages);
		if (buf->vaddr)
			vm_unmap_ram(buf->vaddr, buf->num_pages);
		sg_free_table(&buf->sg_table);
		while (--i >= 0)
			__free_page(buf->pages[i]);
		kfree(buf->pages);
		kfree(buf);
	}
}

static inline int vma_is_io(struct vm_area_struct *vma)
{
	return !!(vma->vm_flags & (VM_IO | VM_PFNMAP));
}

static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
				    unsigned long size, int write)
{
	struct vb2_dma_sg_buf *buf;
	unsigned long first, last;
	int num_pages_from_user;
	struct vm_area_struct *vma;

	buf = kzalloc(sizeof *buf, GFP_KERNEL);
	if (!buf)
		return NULL;

	buf->vaddr = NULL;
	buf->write = write;
	buf->offset = vaddr & ~PAGE_MASK;
	buf->size = size;

	first = (vaddr           & PAGE_MASK) >> PAGE_SHIFT;
	last  = ((vaddr + size - 1) & PAGE_MASK) >> PAGE_SHIFT;
	buf->num_pages = last - first + 1;

	buf->pages = kzalloc(buf->num_pages * sizeof(struct page *),
			     GFP_KERNEL);
	if (!buf->pages)
		goto userptr_fail_alloc_pages;

	vma = find_vma(current->mm, vaddr);
	if (!vma) {
		dprintk(1, "no vma for address %lu\n", vaddr);
		goto userptr_fail_find_vma;
	}

	if (vma->vm_end < vaddr + size) {
		dprintk(1, "vma at %lu is too small for %lu bytes\n",
			vaddr, size);
		goto userptr_fail_find_vma;
	}

	buf->vma = vb2_get_vma(vma);
	if (!buf->vma) {
		dprintk(1, "failed to copy vma\n");
		goto userptr_fail_find_vma;
	}

	if (vma_is_io(buf->vma)) {
		for (num_pages_from_user = 0;
		     num_pages_from_user < buf->num_pages;
		     ++num_pages_from_user, vaddr += PAGE_SIZE) {
			unsigned long pfn;

			if (follow_pfn(buf->vma, vaddr, &pfn)) {
				dprintk(1, "no page for address %lu\n", vaddr);
				break;
			}
			buf->pages[num_pages_from_user] = pfn_to_page(pfn);
		}
	} else
		num_pages_from_user = get_user_pages(current, current->mm,
					     vaddr & PAGE_MASK,
					     buf->num_pages,
					     write,
					     1, /* force */
					     buf->pages,
					     NULL);

	if (num_pages_from_user != buf->num_pages)
		goto userptr_fail_get_user_pages;

	if (sg_alloc_table_from_pages(&buf->sg_table, buf->pages,
			buf->num_pages, buf->offset, size, 0))
		goto userptr_fail_alloc_table_from_pages;

	return buf;

userptr_fail_alloc_table_from_pages:
userptr_fail_get_user_pages:
	dprintk(1, "get_user_pages requested/got: %d/%d]\n",
		buf->num_pages, num_pages_from_user);
	if (!vma_is_io(buf->vma))
		while (--num_pages_from_user >= 0)
			put_page(buf->pages[num_pages_from_user]);
	vb2_put_vma(buf->vma);
userptr_fail_find_vma:
	kfree(buf->pages);
userptr_fail_alloc_pages:
	kfree(buf);
	return NULL;
}

/*
 * @put_userptr: inform the allocator that a USERPTR buffer will no longer
 *		 be used
 */
static void vb2_dma_sg_put_userptr(void *buf_priv)
{
	struct vb2_dma_sg_buf *buf = buf_priv;
	int i = buf->num_pages;

	dprintk(1, "%s: Releasing userspace buffer of %d pages\n",
	       __func__, buf->num_pages);
	if (buf->vaddr)
		vm_unmap_ram(buf->vaddr, buf->num_pages);
	sg_free_table(&buf->sg_table);
	while (--i >= 0) {
		if (buf->write)
			set_page_dirty_lock(buf->pages[i]);
		if (!vma_is_io(buf->vma))
			put_page(buf->pages[i]);
	}
	kfree(buf->pages);
	vb2_put_vma(buf->vma);
	kfree(buf);
}

static void *vb2_dma_sg_vaddr(void *buf_priv)
{
	struct vb2_dma_sg_buf *buf = buf_priv;

	BUG_ON(!buf);

	if (!buf->vaddr)
		buf->vaddr = vm_map_ram(buf->pages,
					buf->num_pages,
					-1,
					PAGE_KERNEL);

	/* add offset in case userptr is not page-aligned */
	return buf->vaddr + buf->offset;
}

static unsigned int vb2_dma_sg_num_users(void *buf_priv)
{
	struct vb2_dma_sg_buf *buf = buf_priv;

	return atomic_read(&buf->refcount);
}

static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
{
	struct vb2_dma_sg_buf *buf = buf_priv;
	unsigned long uaddr = vma->vm_start;
	unsigned long usize = vma->vm_end - vma->vm_start;
	int i = 0;

	if (!buf) {
		printk(KERN_ERR "No memory to map\n");
		return -EINVAL;
	}

	do {
		int ret;

		ret = vm_insert_page(vma, uaddr, buf->pages[i++]);
		if (ret) {
			printk(KERN_ERR "Remapping memory, error: %d\n", ret);
			return ret;
		}

		uaddr += PAGE_SIZE;
		usize -= PAGE_SIZE;
	} while (usize > 0);


	/*
	 * Use common vm_area operations to track buffer refcount.
	 */
	vma->vm_private_data	= &buf->handler;
	vma->vm_ops		= &vb2_common_vm_ops;

	vma->vm_ops->open(vma);

	return 0;
}

static void *vb2_dma_sg_cookie(void *buf_priv)
{
	struct vb2_dma_sg_buf *buf = buf_priv;

	return &buf->sg_table;
}

const struct vb2_mem_ops vb2_dma_sg_memops = {
	.alloc		= vb2_dma_sg_alloc,
	.put		= vb2_dma_sg_put,
	.get_userptr	= vb2_dma_sg_get_userptr,
	.put_userptr	= vb2_dma_sg_put_userptr,
	.vaddr		= vb2_dma_sg_vaddr,
	.mmap		= vb2_dma_sg_mmap,
	.num_users	= vb2_dma_sg_num_users,
	.cookie		= vb2_dma_sg_cookie,
};
EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);

MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
MODULE_AUTHOR("Andrzej Pietrasiewicz");
MODULE_LICENSE("GPL");