136 lines
3.8 KiB
C
136 lines
3.8 KiB
C
/*
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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 <pawel@osciak.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 <media/videobuf2-v4l2.h>
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#include <media/videobuf2-memops.h>
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/**
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* vb2_create_framevec() - map virtual addresses to pfns
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* @start: Virtual user address where we start mapping
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* @length: Length of a range to map
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* @write: Should we map for writing into the area
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*
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* This function allocates and fills in a vector with pfns corresponding to
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* virtual address range passed in arguments. If pfns have corresponding pages,
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* page references are also grabbed to pin pages in memory. The function
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* returns pointer to the vector on success and error pointer in case of
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* failure. Returned vector needs to be freed via vb2_destroy_pfnvec().
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*/
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struct frame_vector *vb2_create_framevec(unsigned long start,
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unsigned long length,
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bool write)
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{
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int ret;
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unsigned long first, last;
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unsigned long nr;
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struct frame_vector *vec;
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unsigned int flags = FOLL_FORCE;
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if (write)
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flags |= FOLL_WRITE;
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first = start >> PAGE_SHIFT;
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last = (start + length - 1) >> PAGE_SHIFT;
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nr = last - first + 1;
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vec = frame_vector_create(nr);
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if (!vec)
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return ERR_PTR(-ENOMEM);
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ret = get_vaddr_frames(start & PAGE_MASK, nr, flags, vec);
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if (ret < 0)
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goto out_destroy;
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/* We accept only complete set of PFNs */
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if (ret != nr) {
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ret = -EFAULT;
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goto out_release;
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}
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return vec;
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out_release:
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put_vaddr_frames(vec);
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out_destroy:
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frame_vector_destroy(vec);
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return ERR_PTR(ret);
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}
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EXPORT_SYMBOL(vb2_create_framevec);
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/**
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* vb2_destroy_framevec() - release vector of mapped pfns
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* @vec: vector of pfns / pages to release
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*
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* This releases references to all pages in the vector @vec (if corresponding
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* pfns are backed by pages) and frees the passed vector.
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*/
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void vb2_destroy_framevec(struct frame_vector *vec)
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{
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put_vaddr_frames(vec);
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frame_vector_destroy(vec);
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}
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EXPORT_SYMBOL(vb2_destroy_framevec);
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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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pr_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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pr_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 <pawel@osciak.com>");
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MODULE_LICENSE("GPL");
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