2 * videobuf2-dma-sg.c - dma scatter/gather memory allocator for videobuf2
4 * Copyright (C) 2010 Samsung Electronics
6 * Author: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
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.
13 #include <linux/module.h>
15 #include <linux/scatterlist.h>
16 #include <linux/sched.h>
17 #include <linux/slab.h>
18 #include <linux/vmalloc.h>
20 #include <media/videobuf2-core.h>
21 #include <media/videobuf2-memops.h>
22 #include <media/videobuf2-dma-sg.h>
24 struct vb2_dma_sg_buf {
29 struct vb2_dma_sg_desc sg_desc;
31 struct vb2_vmarea_handler handler;
34 static void vb2_dma_sg_put(void *buf_priv);
36 static void *vb2_dma_sg_alloc(void *alloc_ctx, unsigned long size)
38 struct vb2_dma_sg_buf *buf;
41 buf = kzalloc(sizeof *buf, GFP_KERNEL);
48 buf->sg_desc.size = size;
49 buf->sg_desc.num_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
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);
57 buf->pages = kzalloc(buf->sg_desc.num_pages * sizeof(struct page *),
60 goto fail_pages_array_alloc;
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);
70 buf->handler.refcount = &buf->refcount;
71 buf->handler.put = vb2_dma_sg_put;
72 buf->handler.arg = buf;
74 atomic_inc(&buf->refcount);
76 printk(KERN_DEBUG "%s: Allocated buffer of %d pages\n",
77 __func__, buf->sg_desc.num_pages);
80 buf->vaddr = vm_map_ram(buf->pages,
81 buf->sg_desc.num_pages,
88 __free_page(buf->pages[i]);
91 fail_pages_array_alloc:
92 vfree(buf->sg_desc.sglist);
99 static void vb2_dma_sg_put(void *buf_priv)
101 struct vb2_dma_sg_buf *buf = buf_priv;
102 int i = buf->sg_desc.num_pages;
104 if (atomic_dec_and_test(&buf->refcount)) {
105 printk(KERN_DEBUG "%s: Freeing buffer of %d pages\n", __func__,
106 buf->sg_desc.num_pages);
108 vm_unmap_ram(buf->vaddr, buf->sg_desc.num_pages);
109 vfree(buf->sg_desc.sglist);
111 __free_page(buf->pages[i]);
117 static void *vb2_dma_sg_get_userptr(void *alloc_ctx, unsigned long vaddr,
118 unsigned long size, int write)
120 struct vb2_dma_sg_buf *buf;
121 unsigned long first, last;
122 int num_pages_from_user, i;
124 buf = kzalloc(sizeof *buf, GFP_KERNEL);
130 buf->offset = vaddr & ~PAGE_MASK;
131 buf->sg_desc.size = size;
133 first = (vaddr & PAGE_MASK) >> PAGE_SHIFT;
134 last = ((vaddr + size - 1) & PAGE_MASK) >> PAGE_SHIFT;
135 buf->sg_desc.num_pages = last - first + 1;
137 buf->sg_desc.sglist = vzalloc(
138 buf->sg_desc.num_pages * sizeof(*buf->sg_desc.sglist));
139 if (!buf->sg_desc.sglist)
140 goto userptr_fail_sglist_alloc;
142 sg_init_table(buf->sg_desc.sglist, buf->sg_desc.num_pages);
144 buf->pages = kzalloc(buf->sg_desc.num_pages * sizeof(struct page *),
147 goto userptr_fail_pages_array_alloc;
149 down_read(¤t->mm->mmap_sem);
150 num_pages_from_user = get_user_pages(current, current->mm,
152 buf->sg_desc.num_pages,
157 up_read(¤t->mm->mmap_sem);
158 if (num_pages_from_user != buf->sg_desc.num_pages)
159 goto userptr_fail_get_user_pages;
161 sg_set_page(&buf->sg_desc.sglist[0], buf->pages[0],
162 PAGE_SIZE - buf->offset, buf->offset);
163 size -= PAGE_SIZE - buf->offset;
164 for (i = 1; i < buf->sg_desc.num_pages; ++i) {
165 sg_set_page(&buf->sg_desc.sglist[i], buf->pages[i],
166 min_t(size_t, PAGE_SIZE, size), 0);
167 size -= min_t(size_t, PAGE_SIZE, size);
171 userptr_fail_get_user_pages:
172 printk(KERN_DEBUG "get_user_pages requested/got: %d/%d]\n",
173 num_pages_from_user, buf->sg_desc.num_pages);
174 while (--num_pages_from_user >= 0)
175 put_page(buf->pages[num_pages_from_user]);
178 userptr_fail_pages_array_alloc:
179 vfree(buf->sg_desc.sglist);
181 userptr_fail_sglist_alloc:
187 * @put_userptr: inform the allocator that a USERPTR buffer will no longer
190 static void vb2_dma_sg_put_userptr(void *buf_priv)
192 struct vb2_dma_sg_buf *buf = buf_priv;
193 int i = buf->sg_desc.num_pages;
195 printk(KERN_DEBUG "%s: Releasing userspace buffer of %d pages\n",
196 __func__, buf->sg_desc.num_pages);
198 vm_unmap_ram(buf->vaddr, buf->sg_desc.num_pages);
201 set_page_dirty_lock(buf->pages[i]);
202 put_page(buf->pages[i]);
204 vfree(buf->sg_desc.sglist);
209 static void *vb2_dma_sg_vaddr(void *buf_priv)
211 struct vb2_dma_sg_buf *buf = buf_priv;
216 buf->vaddr = vm_map_ram(buf->pages,
217 buf->sg_desc.num_pages,
221 /* add offset in case userptr is not page-aligned */
222 return buf->vaddr + buf->offset;
225 static unsigned int vb2_dma_sg_num_users(void *buf_priv)
227 struct vb2_dma_sg_buf *buf = buf_priv;
229 return atomic_read(&buf->refcount);
232 static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma)
234 struct vb2_dma_sg_buf *buf = buf_priv;
235 unsigned long uaddr = vma->vm_start;
236 unsigned long usize = vma->vm_end - vma->vm_start;
240 printk(KERN_ERR "No memory to map\n");
247 ret = vm_insert_page(vma, uaddr, buf->pages[i++]);
249 printk(KERN_ERR "Remapping memory, error: %d\n", ret);
259 * Use common vm_area operations to track buffer refcount.
261 vma->vm_private_data = &buf->handler;
262 vma->vm_ops = &vb2_common_vm_ops;
264 vma->vm_ops->open(vma);
269 static void *vb2_dma_sg_cookie(void *buf_priv)
271 struct vb2_dma_sg_buf *buf = buf_priv;
273 return &buf->sg_desc;
276 const struct vb2_mem_ops vb2_dma_sg_memops = {
277 .alloc = vb2_dma_sg_alloc,
278 .put = vb2_dma_sg_put,
279 .get_userptr = vb2_dma_sg_get_userptr,
280 .put_userptr = vb2_dma_sg_put_userptr,
281 .vaddr = vb2_dma_sg_vaddr,
282 .mmap = vb2_dma_sg_mmap,
283 .num_users = vb2_dma_sg_num_users,
284 .cookie = vb2_dma_sg_cookie,
286 EXPORT_SYMBOL_GPL(vb2_dma_sg_memops);
288 MODULE_DESCRIPTION("dma scatter/gather memory handling routines for videobuf2");
289 MODULE_AUTHOR("Andrzej Pietrasiewicz");
290 MODULE_LICENSE("GPL");