2 * videobuf2-memops.c - generic memory handling routines for videobuf2
4 * Copyright (C) 2010 Samsung Electronics
6 * Author: Pawel Osciak <pawel@osciak.com>
7 * Marek Szyprowski <m.szyprowski@samsung.com>
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation.
14 #include <linux/slab.h>
15 #include <linux/module.h>
16 #include <linux/dma-mapping.h>
17 #include <linux/vmalloc.h>
19 #include <linux/sched.h>
20 #include <linux/file.h>
22 #include <media/videobuf2-core.h>
23 #include <media/videobuf2-memops.h>
26 * vb2_get_vma() - acquire and lock the virtual memory area
27 * @vma: given virtual memory area
29 * This function attempts to acquire an area mapped in the userspace for
30 * the duration of a hardware operation. The area is "locked" by performing
31 * the same set of operation that are done when process calls fork() and
32 * memory areas are duplicated.
34 * Returns a copy of a virtual memory region on success or NULL.
36 struct vm_area_struct *vb2_get_vma(struct vm_area_struct *vma)
38 struct vm_area_struct *vma_copy;
40 vma_copy = kmalloc(sizeof(*vma_copy), GFP_KERNEL);
44 if (vma->vm_ops && vma->vm_ops->open)
45 vma->vm_ops->open(vma);
48 get_file(vma->vm_file);
50 memcpy(vma_copy, vma, sizeof(*vma));
52 vma_copy->vm_mm = NULL;
53 vma_copy->vm_next = NULL;
54 vma_copy->vm_prev = NULL;
60 * vb2_put_userptr() - release a userspace virtual memory area
61 * @vma: virtual memory region associated with the area to be released
63 * This function releases the previously acquired memory area after a hardware
66 void vb2_put_vma(struct vm_area_struct *vma)
74 if (vma->vm_ops && vma->vm_ops->close)
75 vma->vm_ops->close(vma);
79 EXPORT_SYMBOL_GPL(vb2_put_vma);
82 * vb2_get_contig_userptr() - lock physically contiguous userspace mapped memory
83 * @vaddr: starting virtual address of the area to be verified
84 * @size: size of the area
85 * @res_paddr: will return physical address for the given vaddr
86 * @res_vma: will return locked copy of struct vm_area for the given area
88 * This function will go through memory area of size @size mapped at @vaddr and
89 * verify that the underlying physical pages are contiguous. If they are
90 * contiguous the virtual memory area is locked and a @res_vma is filled with
91 * the copy and @res_pa set to the physical address of the buffer.
93 * Returns 0 on success.
95 int vb2_get_contig_userptr(unsigned long vaddr, unsigned long size,
96 struct vm_area_struct **res_vma, dma_addr_t *res_pa)
98 struct mm_struct *mm = current->mm;
99 struct vm_area_struct *vma;
100 unsigned long offset, start, end;
101 unsigned long this_pfn, prev_pfn;
106 offset = start & ~PAGE_MASK;
109 down_read(&mm->mmap_sem);
110 vma = find_vma(mm, start);
112 if (vma == NULL || vma->vm_end < end)
115 for (prev_pfn = 0; start < end; start += PAGE_SIZE) {
116 ret = follow_pfn(vma, start, &this_pfn);
121 pa = this_pfn << PAGE_SHIFT;
122 else if (this_pfn != prev_pfn + 1) {
130 * Memory is contigous, lock vma and return to the caller
132 *res_vma = vb2_get_vma(vma);
133 if (*res_vma == NULL) {
137 *res_pa = pa + offset;
141 up_read(&mm->mmap_sem);
144 EXPORT_SYMBOL_GPL(vb2_get_contig_userptr);
147 * vb2_mmap_pfn_range() - map physical pages to userspace
148 * @vma: virtual memory region for the mapping
149 * @paddr: starting physical address of the memory to be mapped
150 * @size: size of the memory to be mapped
151 * @vm_ops: vm operations to be assigned to the created area
152 * @priv: private data to be associated with the area
154 * Returns 0 on success.
156 int vb2_mmap_pfn_range(struct vm_area_struct *vma, unsigned long paddr,
158 const struct vm_operations_struct *vm_ops,
163 size = min_t(unsigned long, vma->vm_end - vma->vm_start, size);
165 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
166 ret = remap_pfn_range(vma, vma->vm_start, paddr >> PAGE_SHIFT,
167 size, vma->vm_page_prot);
169 printk(KERN_ERR "Remapping memory failed, error: %d\n", ret);
173 vma->vm_flags |= VM_DONTEXPAND | VM_RESERVED;
174 vma->vm_private_data = priv;
175 vma->vm_ops = vm_ops;
177 vma->vm_ops->open(vma);
179 pr_debug("%s: mapped paddr 0x%08lx at 0x%08lx, size %ld\n",
180 __func__, paddr, vma->vm_start, size);
184 EXPORT_SYMBOL_GPL(vb2_mmap_pfn_range);
187 * vb2_common_vm_open() - increase refcount of the vma
188 * @vma: virtual memory region for the mapping
190 * This function adds another user to the provided vma. It expects
191 * struct vb2_vmarea_handler pointer in vma->vm_private_data.
193 static void vb2_common_vm_open(struct vm_area_struct *vma)
195 struct vb2_vmarea_handler *h = vma->vm_private_data;
197 pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n",
198 __func__, h, atomic_read(h->refcount), vma->vm_start,
201 atomic_inc(h->refcount);
205 * vb2_common_vm_close() - decrease refcount of the vma
206 * @vma: virtual memory region for the mapping
208 * This function releases the user from the provided vma. It expects
209 * struct vb2_vmarea_handler pointer in vma->vm_private_data.
211 static void vb2_common_vm_close(struct vm_area_struct *vma)
213 struct vb2_vmarea_handler *h = vma->vm_private_data;
215 pr_debug("%s: %p, refcount: %d, vma: %08lx-%08lx\n",
216 __func__, h, atomic_read(h->refcount), vma->vm_start,
223 * vb2_common_vm_ops - common vm_ops used for tracking refcount of mmaped
226 const struct vm_operations_struct vb2_common_vm_ops = {
227 .open = vb2_common_vm_open,
228 .close = vb2_common_vm_close,
230 EXPORT_SYMBOL_GPL(vb2_common_vm_ops);
232 MODULE_DESCRIPTION("common memory handling routines for videobuf2");
233 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
234 MODULE_LICENSE("GPL");