[media] v4l: videobuf2: add generic memory handling routines (004cc378) · Commits · e / devices / android_kernel_fairphone_FP5

drivers/media/video/Kconfig

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Original line number	Diff line number	Diff line
		@@ -47,6 +47,9 @@ config V4L2_MEM2MEM_DEV
		config VIDEOBUF2_CORE
		tristate

		config VIDEOBUF2_MEMOPS
		tristate

		#
		# Multimedia Video device configuration
		#

drivers/media/video/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -112,6 +112,7 @@ obj-$(CONFIG_VIDEOBUF_DVB) += videobuf-dvb.o
		obj-$(CONFIG_VIDEO_BTCX) += btcx-risc.o

		obj-$(CONFIG_VIDEOBUF2_CORE) += videobuf2-core.o
		obj-$(CONFIG_VIDEOBUF2_MEMOPS) += videobuf2-memops.o

		obj-$(CONFIG_V4L2_MEM2MEM_DEV) += v4l2-mem2mem.o

drivers/media/video/videobuf2-memops.c

0 → 100644

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Original line number	Diff line number	Diff line
		/*
		* videobuf2-memops.c - generic memory handling routines for videobuf2
		*
		* Copyright (C) 2010 Samsung Electronics
		*
		* Author: Pawel Osciak <p.osciak@samsung.com>
		* Marek Szyprowski <m.szyprowski@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/slab.h>
		#include <linux/module.h>
		#include <linux/dma-mapping.h>
		#include <linux/vmalloc.h>
		#include <linux/mm.h>
		#include <linux/sched.h>
		#include <linux/file.h>
		#include <linux/slab.h>

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

		/**
		* vb2_get_vma() - acquire and lock the virtual memory area
		* @vma: given virtual memory area
		*
		* This function attempts to acquire an area mapped in the userspace for
		* the duration of a hardware operation. The area is "locked" by performing
		* the same set of operation that are done when process calls fork() and
		* memory areas are duplicated.
		*
		* Returns a copy of a virtual memory region on success or NULL.
		*/
		struct vm_area_struct vb2_get_vma(struct vm_area_struct vma)
		{
		struct vm_area_struct *vma_copy;

		vma_copy = kmalloc(sizeof(*vma_copy), GFP_KERNEL);
		if (vma_copy == NULL)
		return NULL;

		if (vma->vm_ops && vma->vm_ops->open)
		vma->vm_ops->open(vma);

		if (vma->vm_file)
		get_file(vma->vm_file);

		memcpy(vma_copy, vma, sizeof(*vma));

		vma_copy->vm_mm = NULL;
		vma_copy->vm_next = NULL;
		vma_copy->vm_prev = NULL;

		return vma_copy;
		}

		/**
		* vb2_put_userptr() - release a userspace virtual memory area
		* @vma: virtual memory region associated with the area to be released
		*
		* This function releases the previously acquired memory area after a hardware
		* operation.
		*/
		void vb2_put_vma(struct vm_area_struct *vma)
		{
		if (!vma)
		return;

		if (vma->vm_file)
		fput(vma->vm_file);

		if (vma->vm_ops && vma->vm_ops->close)
		vma->vm_ops->close(vma);

		kfree(vma);
		}

		/**
		* vb2_get_contig_userptr() - lock physically contiguous userspace mapped memory
		* @vaddr: starting virtual address of the area to be verified
		* @size: size of the area
		* @res_paddr: will return physical address for the given vaddr
		* @res_vma: will return locked copy of struct vm_area for the given area
		*
		* This function will go through memory area of size @size mapped at @vaddr and
		* verify that the underlying physical pages are contiguous. If they are
		* contiguous the virtual memory area is locked and a @res_vma is filled with
		* the copy and @res_pa set to the physical address of the buffer.
		*
		* Returns 0 on success.
		*/
		int vb2_get_contig_userptr(unsigned long vaddr, unsigned long size,
		struct vm_area_struct *res_vma, dma_addr_t res_pa)
		{
		struct mm_struct *mm = current->mm;
		struct vm_area_struct *vma;
		unsigned long offset, start, end;
		unsigned long this_pfn, prev_pfn;
		dma_addr_t pa = 0;
		int ret = -EFAULT;

		start = vaddr;
		offset = start & ~PAGE_MASK;
		end = start + size;

		down_read(&mm->mmap_sem);
		vma = find_vma(mm, start);

		if (vma == NULL \|\| vma->vm_end < end)
		goto done;

		for (prev_pfn = 0; start < end; start += PAGE_SIZE) {
		ret = follow_pfn(vma, start, &this_pfn);
		if (ret)
		goto done;

		if (prev_pfn == 0)
		pa = this_pfn << PAGE_SHIFT;
		else if (this_pfn != prev_pfn + 1) {
		ret = -EFAULT;
		goto done;
		}
		prev_pfn = this_pfn;
		}

		/*
		* Memory is contigous, lock vma and return to the caller
		*/
		*res_vma = vb2_get_vma(vma);
		if (*res_vma == NULL) {
		ret = -ENOMEM;
		goto done;
		}
		*res_pa = pa + offset;
		ret = 0;

		done:
		up_read(&mm->mmap_sem);
		return ret;
		}

		/**
		* vb2_mmap_pfn_range() - map physical pages to userspace
		* @vma: virtual memory region for the mapping
		* @paddr: starting physical address of the memory to be mapped
		* @size: size of the memory to be mapped
		* @vm_ops: vm operations to be assigned to the created area
		* @priv: private data to be associated with the area
		*
		* Returns 0 on success.
		*/
		int vb2_mmap_pfn_range(struct vm_area_struct *vma, unsigned long paddr,
		unsigned long size,
		const struct vm_operations_struct *vm_ops,
		void *priv)
		{
		int ret;

		size = min_t(unsigned long, vma->vm_end - vma->vm_start, size);

		vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
		ret = remap_pfn_range(vma, vma->vm_start, paddr >> PAGE_SHIFT,
		size, vma->vm_page_prot);
		if (ret) {
		printk(KERN_ERR "Remapping memory failed, error: %d\n", ret);
		return ret;
		}

		vma->vm_flags \|= VM_DONTEXPAND \| VM_RESERVED;
		vma->vm_private_data = priv;
		vma->vm_ops = vm_ops;

		vma->vm_ops->open(vma);

		printk(KERN_DEBUG "%s: mapped paddr 0x%08lx at 0x%08lx, size %ld\n",
		__func__, paddr, vma->vm_start, size);

		return 0;
		}

		/**
		* vb2_common_vm_open() - increase refcount of the vma
		* @vma: virtual memory region for the mapping
		*
		* This function adds another user to the provided vma. It expects
		* struct vb2_vmarea_handler pointer in vma->vm_private_data.
		*/
		static void vb2_common_vm_open(struct vm_area_struct *vma)
		{
		struct vb2_vmarea_handler *h = vma->vm_private_data;

		printk(KERN_DEBUG "%s: %p, refcount: %d, vma: %08lx-%08lx\n",
		__func__, h, atomic_read(h->refcount), vma->vm_start,
		vma->vm_end);

		atomic_inc(h->refcount);
		}

		/**
		* vb2_common_vm_close() - decrease refcount of the vma
		* @vma: virtual memory region for the mapping
		*
		* This function releases the user from the provided vma. It expects
		* struct vb2_vmarea_handler pointer in vma->vm_private_data.
		*/
		static void vb2_common_vm_close(struct vm_area_struct *vma)
		{
		struct vb2_vmarea_handler *h = vma->vm_private_data;

		printk(KERN_DEBUG "%s: %p, refcount: %d, vma: %08lx-%08lx\n",
		__func__, h, atomic_read(h->refcount), vma->vm_start,
		vma->vm_end);

		h->put(h->arg);
		}

		/**
		* vb2_common_vm_ops - common vm_ops used for tracking refcount of mmaped
		* video buffers
		*/
		const struct vm_operations_struct vb2_common_vm_ops = {
		.open = vb2_common_vm_open,
		.close = vb2_common_vm_close,
		};
		EXPORT_SYMBOL_GPL(vb2_common_vm_ops);

		MODULE_DESCRIPTION("common memory handling routines for videobuf2");
		MODULE_AUTHOR("Pawel Osciak");
		MODULE_LICENSE("GPL");

include/media/videobuf2-memops.h

0 → 100644

+45 −0

Original line number	Diff line number	Diff line
		/*
		* videobuf2-memops.h - generic memory handling routines for videobuf2
		*
		* Copyright (C) 2010 Samsung Electronics
		*
		* Author: Pawel Osciak <p.osciak@samsung.com>
		* Marek Szyprowski <m.szyprowski@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.
		*/

		#ifndef _MEDIA_VIDEOBUF2_MEMOPS_H
		#define _MEDIA_VIDEOBUF2_MEMOPS_H

		#include <media/videobuf2-core.h>

		/**
		* vb2_vmarea_handler - common vma refcount tracking handler
		* @refcount: pointer to refcount entry in the buffer
		* @put: callback to function that decreases buffer refcount
		* @arg: argument for @put callback
		*/
		struct vb2_vmarea_handler {
		atomic_t *refcount;
		void (put)(void arg);
		void *arg;
		};

		extern const struct vm_operations_struct vb2_common_vm_ops;

		int vb2_get_contig_userptr(unsigned long vaddr, unsigned long size,
		struct vm_area_struct *res_vma, dma_addr_t res_pa);

		int vb2_mmap_pfn_range(struct vm_area_struct *vma, unsigned long paddr,
		unsigned long size,
		const struct vm_operations_struct *vm_ops,
		void *priv);

		struct vm_area_struct vb2_get_vma(struct vm_area_struct vma);
		void vb2_put_vma(struct vm_area_struct *vma);


		#endif