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 = vmalloc(buf->sg_desc.num_pages *
52 				      sizeof(*buf->sg_desc.sglist));
53 	if (!buf->sg_desc.sglist)
54 		goto fail_sglist_alloc;
55 	memset(buf->sg_desc.sglist, 0, buf->sg_desc.num_pages *
56 	       sizeof(*buf->sg_desc.sglist));
57 	sg_init_table(buf->sg_desc.sglist, buf->sg_desc.num_pages);
58 
59 	buf->pages = kzalloc(buf->sg_desc.num_pages * sizeof(struct page *),
60 			     GFP_KERNEL);
61 	if (!buf->pages)
62 		goto fail_pages_array_alloc;
63 
64 	for (i = 0; i < buf->sg_desc.num_pages; ++i) {
65 		buf->pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO);
66 		if (NULL == buf->pages[i])
67 			goto fail_pages_alloc;
68 		sg_set_page(&buf->sg_desc.sglist[i],
69 			    buf->pages[i], PAGE_SIZE, 0);
70 	}
71 
72 	buf->handler.refcount = &buf->refcount;
73 	buf->handler.put = vb2_dma_sg_put;
74 	buf->handler.arg = buf;
75 
76 	atomic_inc(&buf->refcount);
77 
78 	printk(KERN_DEBUG "%s: Allocated buffer of %d pages\n",
79 		__func__, buf->sg_desc.num_pages);
80 
81 	if (!buf->vaddr)
82 		buf->vaddr = vm_map_ram(buf->pages,
83 					buf->sg_desc.num_pages,
84 					-1,
85 					PAGE_KERNEL);
86 	return buf;
87 
88 fail_pages_alloc:
89 	while (--i >= 0)
90 		__free_page(buf->pages[i]);
91 	kfree(buf->pages);
92 
93 fail_pages_array_alloc:
94 	vfree(buf->sg_desc.sglist);
95 
96 fail_sglist_alloc:
97 	kfree(buf);
98 	return NULL;
99 }
100 
vb2_dma_sg_put(void * buf_priv)101 static void vb2_dma_sg_put(void *buf_priv)
102 {
103 	struct vb2_dma_sg_buf *buf = buf_priv;
104 	int i = buf->sg_desc.num_pages;
105 
106 	if (atomic_dec_and_test(&buf->refcount)) {
107 		printk(KERN_DEBUG "%s: Freeing buffer of %d pages\n", __func__,
108 			buf->sg_desc.num_pages);
109 		if (buf->vaddr)
110 			vm_unmap_ram(buf->vaddr, buf->sg_desc.num_pages);
111 		vfree(buf->sg_desc.sglist);
112 		while (--i >= 0)
113 			__free_page(buf->pages[i]);
114 		kfree(buf->pages);
115 		kfree(buf);
116 	}
117 }
118 
vb2_dma_sg_get_userptr(void * alloc_ctx,unsigned long vaddr,unsigned long size,int write)119 static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
120 				    unsigned long size, int write)
121 {
122 	struct vb2_dma_sg_buf *buf;
123 	unsigned long first, last;
124 	int num_pages_from_user, i;
125 
126 	buf = kzalloc(sizeof *buf, GFP_KERNEL);
127 	if (!buf)
128 		return NULL;
129 
130 	buf->vaddr = NULL;
131 	buf->write = write;
132 	buf->offset = vaddr & ~PAGE_MASK;
133 	buf->sg_desc.size = size;
134 
135 	first = (vaddr           & PAGE_MASK) >> PAGE_SHIFT;
136 	last  = ((vaddr + size - 1) & PAGE_MASK) >> PAGE_SHIFT;
137 	buf->sg_desc.num_pages = last - first + 1;
138 
139 	buf->sg_desc.sglist = vmalloc(
140 		buf->sg_desc.num_pages * sizeof(*buf->sg_desc.sglist));
141 	if (!buf->sg_desc.sglist)
142 		goto userptr_fail_sglist_alloc;
143 
144 	memset(buf->sg_desc.sglist, 0,
145 		buf->sg_desc.num_pages * sizeof(*buf->sg_desc.sglist));
146 	sg_init_table(buf->sg_desc.sglist, buf->sg_desc.num_pages);
147 
148 	buf->pages = kzalloc(buf->sg_desc.num_pages * sizeof(struct page *),
149 			     GFP_KERNEL);
150 	if (!buf->pages)
151 		goto userptr_fail_pages_array_alloc;
152 
153 	down_read(&current->mm->mmap_sem);
154 	num_pages_from_user = get_user_pages(current, current->mm,
155 					     vaddr & PAGE_MASK,
156 					     buf->sg_desc.num_pages,
157 					     write,
158 					     1, /* force */
159 					     buf->pages,
160 					     NULL);
161 	up_read(&current->mm->mmap_sem);
162 	if (num_pages_from_user != buf->sg_desc.num_pages)
163 		goto userptr_fail_get_user_pages;
164 
165 	sg_set_page(&buf->sg_desc.sglist[0], buf->pages[0],
166 		    PAGE_SIZE - buf->offset, buf->offset);
167 	size -= PAGE_SIZE - buf->offset;
168 	for (i = 1; i < buf->sg_desc.num_pages; ++i) {
169 		sg_set_page(&buf->sg_desc.sglist[i], buf->pages[i],
170 			    min_t(size_t, PAGE_SIZE, size), 0);
171 		size -= min_t(size_t, PAGE_SIZE, size);
172 	}
173 	return buf;
174 
175 userptr_fail_get_user_pages:
176 	printk(KERN_DEBUG "get_user_pages requested/got: %d/%d]\n",
177 	       num_pages_from_user, buf->sg_desc.num_pages);
178 	while (--num_pages_from_user >= 0)
179 		put_page(buf->pages[num_pages_from_user]);
180 	kfree(buf->pages);
181 
182 userptr_fail_pages_array_alloc:
183 	vfree(buf->sg_desc.sglist);
184 
185 userptr_fail_sglist_alloc:
186 	kfree(buf);
187 	return NULL;
188 }
189 
190 /*
191  * @put_userptr: inform the allocator that a USERPTR buffer will no longer
192  *		 be used
193  */
vb2_dma_sg_put_userptr(void * buf_priv)194 static void vb2_dma_sg_put_userptr(void *buf_priv)
195 {
196 	struct vb2_dma_sg_buf *buf = buf_priv;
197 	int i = buf->sg_desc.num_pages;
198 
199 	printk(KERN_DEBUG "%s: Releasing userspace buffer of %d pages\n",
200 	       __func__, buf->sg_desc.num_pages);
201 	if (buf->vaddr)
202 		vm_unmap_ram(buf->vaddr, buf->sg_desc.num_pages);
203 	while (--i >= 0) {
204 		if (buf->write)
205 			set_page_dirty_lock(buf->pages[i]);
206 		put_page(buf->pages[i]);
207 	}
208 	vfree(buf->sg_desc.sglist);
209 	kfree(buf->pages);
210 	kfree(buf);
211 }
212 
vb2_dma_sg_vaddr(void * buf_priv)213 static void *vb2_dma_sg_vaddr(void *buf_priv)
214 {
215 	struct vb2_dma_sg_buf *buf = buf_priv;
216 
217 	BUG_ON(!buf);
218 
219 	if (!buf->vaddr)
220 		buf->vaddr = vm_map_ram(buf->pages,
221 					buf->sg_desc.num_pages,
222 					-1,
223 					PAGE_KERNEL);
224 
225 	/* add offset in case userptr is not page-aligned */
226 	return buf->vaddr + buf->offset;
227 }
228 
vb2_dma_sg_num_users(void * buf_priv)229 static unsigned int vb2_dma_sg_num_users(void *buf_priv)
230 {
231 	struct vb2_dma_sg_buf *buf = buf_priv;
232 
233 	return atomic_read(&buf->refcount);
234 }
235 
vb2_dma_sg_mmap(void * buf_priv,struct vm_area_struct * vma)236 static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
237 {
238 	struct vb2_dma_sg_buf *buf = buf_priv;
239 	unsigned long uaddr = vma->vm_start;
240 	unsigned long usize = vma->vm_end - vma->vm_start;
241 	int i = 0;
242 
243 	if (!buf) {
244 		printk(KERN_ERR "No memory to map\n");
245 		return -EINVAL;
246 	}
247 
248 	do {
249 		int ret;
250 
251 		ret = vm_insert_page(vma, uaddr, buf->pages[i++]);
252 		if (ret) {
253 			printk(KERN_ERR "Remapping memory, error: %d\n", ret);
254 			return ret;
255 		}
256 
257 		uaddr += PAGE_SIZE;
258 		usize -= PAGE_SIZE;
259 	} while (usize > 0);
260 
261 
262 	/*
263 	 * Use common vm_area operations to track buffer refcount.
264 	 */
265 	vma->vm_private_data	= &buf->handler;
266 	vma->vm_ops		= &vb2_common_vm_ops;
267 
268 	vma->vm_ops->open(vma);
269 
270 	return 0;
271 }
272 
vb2_dma_sg_cookie(void * buf_priv)273 static void *vb2_dma_sg_cookie(void *buf_priv)
274 {
275 	struct vb2_dma_sg_buf *buf = buf_priv;
276 
277 	return &buf->sg_desc;
278 }
279 
280 const struct vb2_mem_ops vb2_dma_sg_memops = {
281 	.alloc		= vb2_dma_sg_alloc,
282 	.put		= vb2_dma_sg_put,
283 	.get_userptr	= vb2_dma_sg_get_userptr,
284 	.put_userptr	= vb2_dma_sg_put_userptr,
285 	.vaddr		= vb2_dma_sg_vaddr,
286 	.mmap		= vb2_dma_sg_mmap,
287 	.num_users	= vb2_dma_sg_num_users,
288 	.cookie		= vb2_dma_sg_cookie,
289 };
290 EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
291 
292 MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
293 MODULE_AUTHOR("Andrzej Pietrasiewicz");
294 MODULE_LICENSE("GPL");
295