[media] v4l: videobuf2: add generic memory handling routines
Add generic memory handling routines for userspace pointer handling, contiguous memory verification and mapping. Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Pawel Osciak <p.osciak@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> CC: Pawel Osciak <pawel@osciak.com> Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Marek Szyprowski
Mauro Carvalho Chehab
parent
e23ccc0ad9
commit
004cc3781c
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@ -47,6 +47,9 @@ config V4L2_MEM2MEM_DEV
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config VIDEOBUF2_CORE
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tristate
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config VIDEOBUF2_MEMOPS
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tristate
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#
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# Multimedia Video device configuration
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#
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@ -112,6 +112,7 @@ obj-$(CONFIG_VIDEOBUF_DVB) += videobuf-dvb.o
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obj-$(CONFIG_VIDEO_BTCX) += btcx-risc.o
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obj-$(CONFIG_VIDEOBUF2_CORE) += videobuf2-core.o
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obj-$(CONFIG_VIDEOBUF2_MEMOPS) += videobuf2-memops.o
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obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o
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@ -0,0 +1,232 @@
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/*
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* videobuf2-memops.c - generic memory handling routines for videobuf2
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*
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* Copyright (C) 2010 Samsung Electronics
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*
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* Author: Pawel Osciak <p.osciak@samsung.com>
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* Marek Szyprowski <m.szyprowski@samsung.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation.
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*/
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/dma-mapping.h>
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#include <linux/vmalloc.h>
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/file.h>
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#include <linux/slab.h>
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#include <media/videobuf2-core.h>
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#include <media/videobuf2-memops.h>
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/**
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* vb2_get_vma() - acquire and lock the virtual memory area
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* @vma: given virtual memory area
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*
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* This function attempts to acquire an area mapped in the userspace for
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* the duration of a hardware operation. The area is "locked" by performing
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* the same set of operation that are done when process calls fork() and
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* memory areas are duplicated.
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*
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* Returns a copy of a virtual memory region on success or NULL.
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*/
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struct vm_area_struct *vb2_get_vma(struct vm_area_struct *vma)
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{
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struct vm_area_struct *vma_copy;
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vma_copy = kmalloc(sizeof(*vma_copy), GFP_KERNEL);
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if (vma_copy == NULL)
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return NULL;
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if (vma->vm_ops && vma->vm_ops->open)
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vma->vm_ops->open(vma);
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if (vma->vm_file)
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get_file(vma->vm_file);
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memcpy(vma_copy, vma, sizeof(*vma));
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vma_copy->vm_mm = NULL;
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vma_copy->vm_next = NULL;
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vma_copy->vm_prev = NULL;
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return vma_copy;
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}
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/**
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* vb2_put_userptr() - release a userspace virtual memory area
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* @vma: virtual memory region associated with the area to be released
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*
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* This function releases the previously acquired memory area after a hardware
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* operation.
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*/
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void vb2_put_vma(struct vm_area_struct *vma)
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{
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if (!vma)
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return;
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if (vma->vm_file)
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fput(vma->vm_file);
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if (vma->vm_ops && vma->vm_ops->close)
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vma->vm_ops->close(vma);
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kfree(vma);
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}
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/**
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* vb2_get_contig_userptr() - lock physically contiguous userspace mapped memory
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* @vaddr: starting virtual address of the area to be verified
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* @size: size of the area
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* @res_paddr: will return physical address for the given vaddr
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* @res_vma: will return locked copy of struct vm_area for the given area
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*
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* This function will go through memory area of size @size mapped at @vaddr and
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* verify that the underlying physical pages are contiguous. If they are
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* contiguous the virtual memory area is locked and a @res_vma is filled with
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* the copy and @res_pa set to the physical address of the buffer.
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*
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* Returns 0 on success.
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*/
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int vb2_get_contig_userptr(unsigned long vaddr, unsigned long size,
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struct vm_area_struct **res_vma, dma_addr_t *res_pa)
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{
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struct mm_struct *mm = current->mm;
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struct vm_area_struct *vma;
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unsigned long offset, start, end;
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unsigned long this_pfn, prev_pfn;
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dma_addr_t pa = 0;
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int ret = -EFAULT;
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start = vaddr;
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offset = start & ~PAGE_MASK;
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end = start + size;
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down_read(&mm->mmap_sem);
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vma = find_vma(mm, start);
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if (vma == NULL || vma->vm_end < end)
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goto done;
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for (prev_pfn = 0; start < end; start += PAGE_SIZE) {
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ret = follow_pfn(vma, start, &this_pfn);
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if (ret)
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goto done;
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if (prev_pfn == 0)
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pa = this_pfn << PAGE_SHIFT;
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else if (this_pfn != prev_pfn + 1) {
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ret = -EFAULT;
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goto done;
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}
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prev_pfn = this_pfn;
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}
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/*
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* Memory is contigous, lock vma and return to the caller
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*/
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*res_vma = vb2_get_vma(vma);
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if (*res_vma == NULL) {
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ret = -ENOMEM;
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goto done;
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}
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*res_pa = pa + offset;
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ret = 0;
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done:
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up_read(&mm->mmap_sem);
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return ret;
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}
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/**
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* vb2_mmap_pfn_range() - map physical pages to userspace
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* @vma: virtual memory region for the mapping
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* @paddr: starting physical address of the memory to be mapped
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* @size: size of the memory to be mapped
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* @vm_ops: vm operations to be assigned to the created area
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* @priv: private data to be associated with the area
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*
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* Returns 0 on success.
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*/
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int vb2_mmap_pfn_range(struct vm_area_struct *vma, unsigned long paddr,
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unsigned long size,
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const struct vm_operations_struct *vm_ops,
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void *priv)
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{
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int ret;
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size = min_t(unsigned long, vma->vm_end - vma->vm_start, size);
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vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
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ret = remap_pfn_range(vma, vma->vm_start, paddr >> PAGE_SHIFT,
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size, vma->vm_page_prot);
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if (ret) {
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printk(KERN_ERR "Remapping memory failed, error: %d\n", ret);
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return ret;
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}
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vma->vm_flags |= VM_DONTEXPAND | VM_RESERVED;
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vma->vm_private_data = priv;
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vma->vm_ops = vm_ops;
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vma->vm_ops->open(vma);
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printk(KERN_DEBUG "%s: mapped paddr 0x%08lx at 0x%08lx, size %ld\n",
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__func__, paddr, vma->vm_start, size);
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return 0;
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}
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/**
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* vb2_common_vm_open() - increase refcount of the vma
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* @vma: virtual memory region for the mapping
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*
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* This function adds another user to the provided vma. It expects
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* struct vb2_vmarea_handler pointer in vma->vm_private_data.
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*/
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static void vb2_common_vm_open(struct vm_area_struct *vma)
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{
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struct vb2_vmarea_handler *h = vma->vm_private_data;
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printk(KERN_DEBUG "%s: %p, refcount: %d, vma: %08lx-%08lx\n",
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__func__, h, atomic_read(h->refcount), vma->vm_start,
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vma->vm_end);
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atomic_inc(h->refcount);
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}
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/**
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* vb2_common_vm_close() - decrease refcount of the vma
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* @vma: virtual memory region for the mapping
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*
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* This function releases the user from the provided vma. It expects
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* struct vb2_vmarea_handler pointer in vma->vm_private_data.
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*/
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static void vb2_common_vm_close(struct vm_area_struct *vma)
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{
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struct vb2_vmarea_handler *h = vma->vm_private_data;
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printk(KERN_DEBUG "%s: %p, refcount: %d, vma: %08lx-%08lx\n",
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__func__, h, atomic_read(h->refcount), vma->vm_start,
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vma->vm_end);
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h->put(h->arg);
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}
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/**
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* vb2_common_vm_ops - common vm_ops used for tracking refcount of mmaped
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* video buffers
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*/
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const struct vm_operations_struct vb2_common_vm_ops = {
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.open = vb2_common_vm_open,
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.close = vb2_common_vm_close,
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};
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EXPORT_SYMBOL_GPL(vb2_common_vm_ops);
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MODULE_DESCRIPTION("common memory handling routines for videobuf2");
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MODULE_AUTHOR("Pawel Osciak");
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MODULE_LICENSE("GPL");
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@ -0,0 +1,45 @@
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/*
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* videobuf2-memops.h - generic memory handling routines for videobuf2
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*
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* Copyright (C) 2010 Samsung Electronics
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*
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* Author: Pawel Osciak <p.osciak@samsung.com>
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* Marek Szyprowski <m.szyprowski@samsung.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation.
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*/
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#ifndef _MEDIA_VIDEOBUF2_MEMOPS_H
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#define _MEDIA_VIDEOBUF2_MEMOPS_H
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#include <media/videobuf2-core.h>
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/**
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* vb2_vmarea_handler - common vma refcount tracking handler
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* @refcount: pointer to refcount entry in the buffer
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* @put: callback to function that decreases buffer refcount
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* @arg: argument for @put callback
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*/
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struct vb2_vmarea_handler {
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atomic_t *refcount;
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void (*put)(void *arg);
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void *arg;
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};
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extern const struct vm_operations_struct vb2_common_vm_ops;
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int vb2_get_contig_userptr(unsigned long vaddr, unsigned long size,
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struct vm_area_struct **res_vma, dma_addr_t *res_pa);
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int vb2_mmap_pfn_range(struct vm_area_struct *vma, unsigned long paddr,
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unsigned long size,
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const struct vm_operations_struct *vm_ops,
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void *priv);
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struct vm_area_struct *vb2_get_vma(struct vm_area_struct *vma);
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void vb2_put_vma(struct vm_area_struct *vma);
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#endif
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