videobuf2-vmalloc.c
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/*
* videobuf2-vmalloc.c - vmalloc memory allocator for videobuf2
*
* Copyright (C) 2010 Samsung Electronics
*
* Author: Pawel Osciak <pawel@osciak.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/module.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <media/videobuf2-core.h>
#include <media/videobuf2-memops.h>
struct vb2_vmalloc_buf {
void *vaddr;
unsigned long size;
atomic_t refcount;
struct vb2_vmarea_handler handler;
};
static void vb2_vmalloc_put(void *buf_priv);
static void *vb2_vmalloc_alloc(void *alloc_ctx, unsigned long size)
{
struct vb2_vmalloc_buf *buf;
buf = kzalloc(sizeof *buf, GFP_KERNEL);
if (!buf)
return NULL;
buf->size = size;
buf->vaddr = vmalloc_user(buf->size);
buf->handler.refcount = &buf->refcount;
buf->handler.put = vb2_vmalloc_put;
buf->handler.arg = buf;
if (!buf->vaddr) {
printk(KERN_ERR "vmalloc of size %ld failed\n", buf->size);
kfree(buf);
return NULL;
}
atomic_inc(&buf->refcount);
printk(KERN_DEBUG "Allocated vmalloc buffer of size %ld at vaddr=%p\n",
buf->size, buf->vaddr);
return buf;
}
static void vb2_vmalloc_put(void *buf_priv)
{
struct vb2_vmalloc_buf *buf = buf_priv;
if (atomic_dec_and_test(&buf->refcount)) {
printk(KERN_DEBUG "%s: Freeing vmalloc mem at vaddr=%p\n",
__func__, buf->vaddr);
vfree(buf->vaddr);
kfree(buf);
}
}
static void *vb2_vmalloc_vaddr(void *buf_priv)
{
struct vb2_vmalloc_buf *buf = buf_priv;
BUG_ON(!buf);
if (!buf->vaddr) {
printk(KERN_ERR "Address of an unallocated plane requested\n");
return NULL;
}
return buf->vaddr;
}
static unsigned int vb2_vmalloc_num_users(void *buf_priv)
{
struct vb2_vmalloc_buf *buf = buf_priv;
return atomic_read(&buf->refcount);
}
static int vb2_vmalloc_mmap(void *buf_priv, struct vm_area_struct *vma)
{
struct vb2_vmalloc_buf *buf = buf_priv;
int ret;
if (!buf) {
printk(KERN_ERR "No memory to map\n");
return -EINVAL;
}
ret = remap_vmalloc_range(vma, buf->vaddr, 0);
if (ret) {
printk(KERN_ERR "Remapping vmalloc memory, error: %d\n", ret);
return ret;
}
/*
* Make sure that vm_areas for 2 buffers won't be merged together
*/
vma->vm_flags |= VM_DONTEXPAND;
/*
* Use common vm_area operations to track buffer refcount.
*/
vma->vm_private_data = &buf->handler;
vma->vm_ops = &vb2_common_vm_ops;
vma->vm_ops->open(vma);
return 0;
}
const struct vb2_mem_ops vb2_vmalloc_memops = {
.alloc = vb2_vmalloc_alloc,
.put = vb2_vmalloc_put,
.vaddr = vb2_vmalloc_vaddr,
.mmap = vb2_vmalloc_mmap,
.num_users = vb2_vmalloc_num_users,
};
EXPORT_SYMBOL_GPL(vb2_vmalloc_memops);
MODULE_DESCRIPTION("vmalloc memory handling routines for videobuf2");
MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
MODULE_LICENSE("GPL");