drivers/dma-buf/heaps/cma_heap.c - third_party/kernel - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * DMABUF CMA heap exporter
  *
  * Copyright (C) 2012, 2019, 2020 Linaro Ltd.
  * Author: <benjamin.gaignard@linaro.org> for ST-Ericsson.
  *
  * Also utilizing parts of Andrew Davis' SRAM heap:
  * Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/
  *	Andrew F. Davis <afd@ti.com>
  */
 #include <linux/cma.h>
 #include <linux/dma-buf.h>
 #include <linux/dma-heap.h>
 #include <linux/dma-map-ops.h>
 #include <linux/err.h>
 #include <linux/highmem.h>
 #include <linux/io.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/scatterlist.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>


 struct cma_heap {
 	struct dma_heap *heap;
 	struct cma *cma;
 };

 struct cma_heap_buffer {
 	struct cma_heap *heap;
 	struct list_head attachments;
 	struct mutex lock;
 	unsigned long len;
 	struct page *cma_pages;
 	struct page **pages;
 	pgoff_t pagecount;
 	int vmap_cnt;
 	void *vaddr;
 };

 struct dma_heap_attachment {
 	struct device *dev;
 	struct sg_table table;
 	struct list_head list;
 	bool mapped;
 };

 static int cma_heap_attach(struct dma_buf *dmabuf,
 			   struct dma_buf_attachment *attachment)
 {
 	struct cma_heap_buffer *buffer = dmabuf->priv;
 	struct dma_heap_attachment *a;
 	int ret;

 	a = kzalloc(sizeof(*a), GFP_KERNEL);
 	if (!a)
 		return -ENOMEM;

 	ret = sg_alloc_table_from_pages(&a->table, buffer->pages,
 					buffer->pagecount, 0,
 					buffer->pagecount << PAGE_SHIFT,
 					GFP_KERNEL);
 	if (ret) {
 		kfree(a);
 		return ret;
 	}

 	a->dev = attachment->dev;
 	INIT_LIST_HEAD(&a->list);
 	a->mapped = false;

 	attachment->priv = a;

 	mutex_lock(&buffer->lock);
 	list_add(&a->list, &buffer->attachments);
 	mutex_unlock(&buffer->lock);

 	return 0;
 }

 static void cma_heap_detach(struct dma_buf *dmabuf,
 			    struct dma_buf_attachment *attachment)
 {
 	struct cma_heap_buffer *buffer = dmabuf->priv;
 	struct dma_heap_attachment *a = attachment->priv;

 	mutex_lock(&buffer->lock);
 	list_del(&a->list);
 	mutex_unlock(&buffer->lock);

 	sg_free_table(&a->table);
 	kfree(a);
 }

 static struct sg_table *cma_heap_map_dma_buf(struct dma_buf_attachment *attachment,
 					     enum dma_data_direction direction)
 {
 	struct dma_heap_attachment *a = attachment->priv;
 	struct sg_table *table = &a->table;
 	int ret;

 	ret = dma_map_sgtable(attachment->dev, table, direction, 0);
 	if (ret)
 		return ERR_PTR(-ENOMEM);
 	a->mapped = true;
 	return table;
 }

 static void cma_heap_unmap_dma_buf(struct dma_buf_attachment *attachment,
 				   struct sg_table *table,
 				   enum dma_data_direction direction)
 {
 	struct dma_heap_attachment *a = attachment->priv;

 	a->mapped = false;
 	dma_unmap_sgtable(attachment->dev, table, direction, 0);
 }

 static int cma_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
 					     enum dma_data_direction direction)
 {
 	struct cma_heap_buffer *buffer = dmabuf->priv;
 	struct dma_heap_attachment *a;

 	mutex_lock(&buffer->lock);

 	if (buffer->vmap_cnt)
 		invalidate_kernel_vmap_range(buffer->vaddr, buffer->len);

 	list_for_each_entry(a, &buffer->attachments, list) {
 		if (!a->mapped)
 			continue;
 		dma_sync_sgtable_for_cpu(a->dev, &a->table, direction);
 	}
 	mutex_unlock(&buffer->lock);

 	return 0;
 }

 static int cma_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf,
 					   enum dma_data_direction direction)
 {
 	struct cma_heap_buffer *buffer = dmabuf->priv;
 	struct dma_heap_attachment *a;

 	mutex_lock(&buffer->lock);

 	if (buffer->vmap_cnt)
 		flush_kernel_vmap_range(buffer->vaddr, buffer->len);

 	list_for_each_entry(a, &buffer->attachments, list) {
 		if (!a->mapped)
 			continue;
 		dma_sync_sgtable_for_device(a->dev, &a->table, direction);
 	}
 	mutex_unlock(&buffer->lock);

 	return 0;
 }

 static vm_fault_t cma_heap_vm_fault(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
 	struct cma_heap_buffer *buffer = vma->vm_private_data;

 	if (vmf->pgoff >= buffer->pagecount)
 		return VM_FAULT_SIGBUS;

 	return vmf_insert_pfn(vma, vmf->address, page_to_pfn(buffer->pages[vmf->pgoff]));
 }

 static const struct vm_operations_struct dma_heap_vm_ops = {
 	.fault = cma_heap_vm_fault,
 };

 static int cma_heap_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma)
 {
 	struct cma_heap_buffer *buffer = dmabuf->priv;

 	if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) == 0)
 		return -EINVAL;

 	vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);

 	vma->vm_ops = &dma_heap_vm_ops;
 	vma->vm_private_data = buffer;

 	return 0;
 }

 static void *cma_heap_do_vmap(struct cma_heap_buffer *buffer)
 {
 	void *vaddr;

 	vaddr = vmap(buffer->pages, buffer->pagecount, VM_MAP, PAGE_KERNEL);
 	if (!vaddr)
 		return ERR_PTR(-ENOMEM);

 	return vaddr;
 }

 static int cma_heap_vmap(struct dma_buf *dmabuf, struct iosys_map *map)
 {
 	struct cma_heap_buffer *buffer = dmabuf->priv;
 	void *vaddr;
 	int ret = 0;

 	mutex_lock(&buffer->lock);
 	if (buffer->vmap_cnt) {
 		buffer->vmap_cnt++;
 		iosys_map_set_vaddr(map, buffer->vaddr);
 		goto out;
 	}

 	vaddr = cma_heap_do_vmap(buffer);
 	if (IS_ERR(vaddr)) {
 		ret = PTR_ERR(vaddr);
 		goto out;
 	}
 	buffer->vaddr = vaddr;
 	buffer->vmap_cnt++;
 	iosys_map_set_vaddr(map, buffer->vaddr);
 out:
 	mutex_unlock(&buffer->lock);

 	return ret;
 }

 static void cma_heap_vunmap(struct dma_buf *dmabuf, struct iosys_map *map)
 {
 	struct cma_heap_buffer *buffer = dmabuf->priv;

 	mutex_lock(&buffer->lock);
 	if (!--buffer->vmap_cnt) {
 		vunmap(buffer->vaddr);
 		buffer->vaddr = NULL;
 	}
 	mutex_unlock(&buffer->lock);
 	iosys_map_clear(map);
 }

 static void cma_heap_dma_buf_release(struct dma_buf *dmabuf)
 {
 	struct cma_heap_buffer *buffer = dmabuf->priv;
 	struct cma_heap *cma_heap = buffer->heap;

 	if (buffer->vmap_cnt > 0) {
 		WARN(1, "%s: buffer still mapped in the kernel\n", __func__);
 		vunmap(buffer->vaddr);
 		buffer->vaddr = NULL;
 	}

 	/* free page list */
 	kfree(buffer->pages);
 	/* release memory */
 	cma_release(cma_heap->cma, buffer->cma_pages, buffer->pagecount);
 	kfree(buffer);
 }

 static const struct dma_buf_ops cma_heap_buf_ops = {
 	.attach = cma_heap_attach,
 	.detach = cma_heap_detach,
 	.map_dma_buf = cma_heap_map_dma_buf,
 	.unmap_dma_buf = cma_heap_unmap_dma_buf,
 	.begin_cpu_access = cma_heap_dma_buf_begin_cpu_access,
 	.end_cpu_access = cma_heap_dma_buf_end_cpu_access,
 	.mmap = cma_heap_mmap,
 	.vmap = cma_heap_vmap,
 	.vunmap = cma_heap_vunmap,
 	.release = cma_heap_dma_buf_release,
 };

 static struct dma_buf *cma_heap_allocate(struct dma_heap *heap,
 					 unsigned long len,
 					 u32 fd_flags,
 					 u64 heap_flags)
 {
 	struct cma_heap *cma_heap = dma_heap_get_drvdata(heap);
 	struct cma_heap_buffer *buffer;
 	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
 	size_t size = PAGE_ALIGN(len);
 	pgoff_t pagecount = size >> PAGE_SHIFT;
 	unsigned long align = get_order(size);
 	struct page *cma_pages;
 	struct dma_buf *dmabuf;
 	int ret = -ENOMEM;
 	pgoff_t pg;

 	buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
 	if (!buffer)
 		return ERR_PTR(-ENOMEM);

 	INIT_LIST_HEAD(&buffer->attachments);
 	mutex_init(&buffer->lock);
 	buffer->len = size;

 	if (align > CONFIG_CMA_ALIGNMENT)
 		align = CONFIG_CMA_ALIGNMENT;

 	cma_pages = cma_alloc(cma_heap->cma, pagecount, align, false);
 	if (!cma_pages)
 		goto free_buffer;

 	/* Clear the cma pages */
 	if (PageHighMem(cma_pages)) {
 		unsigned long nr_clear_pages = pagecount;
 		struct page *page = cma_pages;

 		while (nr_clear_pages > 0) {
 			void *vaddr = kmap_atomic(page);

 			memset(vaddr, 0, PAGE_SIZE);
 			kunmap_atomic(vaddr);
 			/*
 			 * Avoid wasting time zeroing memory if the process
 			 * has been killed by by SIGKILL
 			 */
 			if (fatal_signal_pending(current))
 				goto free_cma;
 			page++;
 			nr_clear_pages--;
 		}
 	} else {
 		memset(page_address(cma_pages), 0, size);
 	}

 	buffer->pages = kmalloc_array(pagecount, sizeof(*buffer->pages), GFP_KERNEL);
 	if (!buffer->pages) {
 		ret = -ENOMEM;
 		goto free_cma;
 	}

 	for (pg = 0; pg < pagecount; pg++)
 		buffer->pages[pg] = &cma_pages[pg];

 	buffer->cma_pages = cma_pages;
 	buffer->heap = cma_heap;
 	buffer->pagecount = pagecount;

 	/* create the dmabuf */
 	exp_info.exp_name = dma_heap_get_name(heap);
 	exp_info.ops = &cma_heap_buf_ops;
 	exp_info.size = buffer->len;
 	exp_info.flags = fd_flags;
 	exp_info.priv = buffer;
 	dmabuf = dma_buf_export(&exp_info);
 	if (IS_ERR(dmabuf)) {
 		ret = PTR_ERR(dmabuf);
 		goto free_pages;
 	}
 	return dmabuf;

 free_pages:
 	kfree(buffer->pages);
 free_cma:
 	cma_release(cma_heap->cma, cma_pages, pagecount);
 free_buffer:
 	kfree(buffer);

 	return ERR_PTR(ret);
 }

 static const struct dma_heap_ops cma_heap_ops = {
 	.allocate = cma_heap_allocate,
 };

 static int __add_cma_heap(struct cma *cma, void *data)
 {
 	struct cma_heap *cma_heap;
 	struct dma_heap_export_info exp_info;

 	cma_heap = kzalloc(sizeof(*cma_heap), GFP_KERNEL);
 	if (!cma_heap)
 		return -ENOMEM;
 	cma_heap->cma = cma;

 	exp_info.name = cma_get_name(cma);
 	exp_info.ops = &cma_heap_ops;
 	exp_info.priv = cma_heap;

 	cma_heap->heap = dma_heap_add(&exp_info);
 	if (IS_ERR(cma_heap->heap)) {
 		int ret = PTR_ERR(cma_heap->heap);

 		kfree(cma_heap);
 		return ret;
 	}

 	return 0;
 }

 static int add_default_cma_heap(void)
 {
 	struct cma *default_cma = dev_get_cma_area(NULL);
 	int ret = 0;

 	if (default_cma)
 		ret = __add_cma_heap(default_cma, NULL);

 	return ret;
 }
 module_init(add_default_cma_heap);
 MODULE_DESCRIPTION("DMA-BUF CMA Heap");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* DMABUF CMA heap exporter
	*
	* Copyright (C) 2012, 2019, 2020 Linaro Ltd.
	* Author: <benjamin.gaignard@linaro.org> for ST-Ericsson.
	*
	* Also utilizing parts of Andrew Davis' SRAM heap:
	* Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/
	* Andrew F. Davis <afd@ti.com>
	*/
	#include <linux/cma.h>
	#include <linux/dma-buf.h>
	#include <linux/dma-heap.h>
	#include <linux/dma-map-ops.h>
	#include <linux/err.h>
	#include <linux/highmem.h>
	#include <linux/io.h>
	#include <linux/mm.h>
	#include <linux/module.h>
	#include <linux/scatterlist.h>
	#include <linux/slab.h>
	#include <linux/vmalloc.h>


	struct cma_heap {
	struct dma_heap *heap;
	struct cma *cma;
	};

	struct cma_heap_buffer {
	struct cma_heap *heap;
	struct list_head attachments;
	struct mutex lock;
	unsigned long len;
	struct page *cma_pages;
	struct page **pages;
	pgoff_t pagecount;
	int vmap_cnt;
	void *vaddr;
	};

	struct dma_heap_attachment {
	struct device *dev;
	struct sg_table table;
	struct list_head list;
	bool mapped;
	};

	static int cma_heap_attach(struct dma_buf *dmabuf,
	struct dma_buf_attachment *attachment)
	{
	struct cma_heap_buffer *buffer = dmabuf->priv;
	struct dma_heap_attachment *a;
	int ret;

	a = kzalloc(sizeof(*a), GFP_KERNEL);
	if (!a)
	return -ENOMEM;

	ret = sg_alloc_table_from_pages(&a->table, buffer->pages,
	buffer->pagecount, 0,
	buffer->pagecount << PAGE_SHIFT,
	GFP_KERNEL);
	if (ret) {
	kfree(a);
	return ret;
	}

	a->dev = attachment->dev;
	INIT_LIST_HEAD(&a->list);
	a->mapped = false;

	attachment->priv = a;

	mutex_lock(&buffer->lock);
	list_add(&a->list, &buffer->attachments);
	mutex_unlock(&buffer->lock);

	return 0;
	}

	static void cma_heap_detach(struct dma_buf *dmabuf,
	struct dma_buf_attachment *attachment)
	{
	struct cma_heap_buffer *buffer = dmabuf->priv;
	struct dma_heap_attachment *a = attachment->priv;

	mutex_lock(&buffer->lock);
	list_del(&a->list);
	mutex_unlock(&buffer->lock);

	sg_free_table(&a->table);
	kfree(a);
	}

	static struct sg_table cma_heap_map_dma_buf(struct dma_buf_attachment attachment,
	enum dma_data_direction direction)
	{
	struct dma_heap_attachment *a = attachment->priv;
	struct sg_table *table = &a->table;
	int ret;

	ret = dma_map_sgtable(attachment->dev, table, direction, 0);
	if (ret)
	return ERR_PTR(-ENOMEM);
	a->mapped = true;
	return table;
	}

	static void cma_heap_unmap_dma_buf(struct dma_buf_attachment *attachment,
	struct sg_table *table,
	enum dma_data_direction direction)
	{
	struct dma_heap_attachment *a = attachment->priv;

	a->mapped = false;
	dma_unmap_sgtable(attachment->dev, table, direction, 0);
	}

	static int cma_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
	enum dma_data_direction direction)
	{
	struct cma_heap_buffer *buffer = dmabuf->priv;
	struct dma_heap_attachment *a;

	mutex_lock(&buffer->lock);

	if (buffer->vmap_cnt)
	invalidate_kernel_vmap_range(buffer->vaddr, buffer->len);

	list_for_each_entry(a, &buffer->attachments, list) {
	if (!a->mapped)
	continue;
	dma_sync_sgtable_for_cpu(a->dev, &a->table, direction);
	}
	mutex_unlock(&buffer->lock);

	return 0;
	}

	static int cma_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf,
	enum dma_data_direction direction)
	{
	struct cma_heap_buffer *buffer = dmabuf->priv;
	struct dma_heap_attachment *a;

	mutex_lock(&buffer->lock);

	if (buffer->vmap_cnt)
	flush_kernel_vmap_range(buffer->vaddr, buffer->len);

	list_for_each_entry(a, &buffer->attachments, list) {
	if (!a->mapped)
	continue;
	dma_sync_sgtable_for_device(a->dev, &a->table, direction);
	}
	mutex_unlock(&buffer->lock);

	return 0;
	}

	static vm_fault_t cma_heap_vm_fault(struct vm_fault *vmf)
	{
	struct vm_area_struct *vma = vmf->vma;
	struct cma_heap_buffer *buffer = vma->vm_private_data;

	if (vmf->pgoff >= buffer->pagecount)
	return VM_FAULT_SIGBUS;

	return vmf_insert_pfn(vma, vmf->address, page_to_pfn(buffer->pages[vmf->pgoff]));
	}

	static const struct vm_operations_struct dma_heap_vm_ops = {
	.fault = cma_heap_vm_fault,
	};

	static int cma_heap_mmap(struct dma_buf dmabuf, struct vm_area_struct vma)
	{
	struct cma_heap_buffer *buffer = dmabuf->priv;

	if ((vma->vm_flags & (VM_SHARED \| VM_MAYSHARE)) == 0)
	return -EINVAL;

	vm_flags_set(vma, VM_IO \| VM_PFNMAP \| VM_DONTEXPAND \| VM_DONTDUMP);

	vma->vm_ops = &dma_heap_vm_ops;
	vma->vm_private_data = buffer;

	return 0;
	}

	static void cma_heap_do_vmap(struct cma_heap_buffer buffer)
	{
	void *vaddr;

	vaddr = vmap(buffer->pages, buffer->pagecount, VM_MAP, PAGE_KERNEL);
	if (!vaddr)
	return ERR_PTR(-ENOMEM);

	return vaddr;
	}

	static int cma_heap_vmap(struct dma_buf dmabuf, struct iosys_map map)
	{
	struct cma_heap_buffer *buffer = dmabuf->priv;
	void *vaddr;
	int ret = 0;

	mutex_lock(&buffer->lock);
	if (buffer->vmap_cnt) {
	buffer->vmap_cnt++;
	iosys_map_set_vaddr(map, buffer->vaddr);
	goto out;
	}

	vaddr = cma_heap_do_vmap(buffer);
	if (IS_ERR(vaddr)) {
	ret = PTR_ERR(vaddr);
	goto out;
	}
	buffer->vaddr = vaddr;
	buffer->vmap_cnt++;
	iosys_map_set_vaddr(map, buffer->vaddr);
	out:
	mutex_unlock(&buffer->lock);

	return ret;
	}

	static void cma_heap_vunmap(struct dma_buf dmabuf, struct iosys_map map)
	{
	struct cma_heap_buffer *buffer = dmabuf->priv;

	mutex_lock(&buffer->lock);
	if (!--buffer->vmap_cnt) {
	vunmap(buffer->vaddr);
	buffer->vaddr = NULL;
	}
	mutex_unlock(&buffer->lock);
	iosys_map_clear(map);
	}

	static void cma_heap_dma_buf_release(struct dma_buf *dmabuf)
	{
	struct cma_heap_buffer *buffer = dmabuf->priv;
	struct cma_heap *cma_heap = buffer->heap;

	if (buffer->vmap_cnt > 0) {
	WARN(1, "%s: buffer still mapped in the kernel\n", __func__);
	vunmap(buffer->vaddr);
	buffer->vaddr = NULL;
	}

	/* free page list */
	kfree(buffer->pages);
	/* release memory */
	cma_release(cma_heap->cma, buffer->cma_pages, buffer->pagecount);
	kfree(buffer);
	}

	static const struct dma_buf_ops cma_heap_buf_ops = {
	.attach = cma_heap_attach,
	.detach = cma_heap_detach,
	.map_dma_buf = cma_heap_map_dma_buf,
	.unmap_dma_buf = cma_heap_unmap_dma_buf,
	.begin_cpu_access = cma_heap_dma_buf_begin_cpu_access,
	.end_cpu_access = cma_heap_dma_buf_end_cpu_access,
	.mmap = cma_heap_mmap,
	.vmap = cma_heap_vmap,
	.vunmap = cma_heap_vunmap,
	.release = cma_heap_dma_buf_release,
	};

	static struct dma_buf cma_heap_allocate(struct dma_heap heap,
	unsigned long len,
	u32 fd_flags,
	u64 heap_flags)
	{
	struct cma_heap *cma_heap = dma_heap_get_drvdata(heap);
	struct cma_heap_buffer *buffer;
	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
	size_t size = PAGE_ALIGN(len);
	pgoff_t pagecount = size >> PAGE_SHIFT;
	unsigned long align = get_order(size);
	struct page *cma_pages;
	struct dma_buf *dmabuf;
	int ret = -ENOMEM;
	pgoff_t pg;

	buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
	if (!buffer)
	return ERR_PTR(-ENOMEM);

	INIT_LIST_HEAD(&buffer->attachments);
	mutex_init(&buffer->lock);
	buffer->len = size;

	if (align > CONFIG_CMA_ALIGNMENT)
	align = CONFIG_CMA_ALIGNMENT;

	cma_pages = cma_alloc(cma_heap->cma, pagecount, align, false);
	if (!cma_pages)
	goto free_buffer;

	/* Clear the cma pages */
	if (PageHighMem(cma_pages)) {
	unsigned long nr_clear_pages = pagecount;
	struct page *page = cma_pages;

	while (nr_clear_pages > 0) {
	void *vaddr = kmap_atomic(page);

	memset(vaddr, 0, PAGE_SIZE);
	kunmap_atomic(vaddr);
	/*
	* Avoid wasting time zeroing memory if the process
	* has been killed by by SIGKILL
	*/
	if (fatal_signal_pending(current))
	goto free_cma;
	page++;
	nr_clear_pages--;
	}
	} else {
	memset(page_address(cma_pages), 0, size);
	}

	buffer->pages = kmalloc_array(pagecount, sizeof(*buffer->pages), GFP_KERNEL);
	if (!buffer->pages) {
	ret = -ENOMEM;
	goto free_cma;
	}

	for (pg = 0; pg < pagecount; pg++)
	buffer->pages[pg] = &cma_pages[pg];

	buffer->cma_pages = cma_pages;
	buffer->heap = cma_heap;
	buffer->pagecount = pagecount;

	/* create the dmabuf */
	exp_info.exp_name = dma_heap_get_name(heap);
	exp_info.ops = &cma_heap_buf_ops;
	exp_info.size = buffer->len;
	exp_info.flags = fd_flags;
	exp_info.priv = buffer;
	dmabuf = dma_buf_export(&exp_info);
	if (IS_ERR(dmabuf)) {
	ret = PTR_ERR(dmabuf);
	goto free_pages;
	}
	return dmabuf;

	free_pages:
	kfree(buffer->pages);
	free_cma:
	cma_release(cma_heap->cma, cma_pages, pagecount);
	free_buffer:
	kfree(buffer);

	return ERR_PTR(ret);
	}

	static const struct dma_heap_ops cma_heap_ops = {
	.allocate = cma_heap_allocate,
	};

	static int __add_cma_heap(struct cma cma, void data)
	{
	struct cma_heap *cma_heap;
	struct dma_heap_export_info exp_info;

	cma_heap = kzalloc(sizeof(*cma_heap), GFP_KERNEL);
	if (!cma_heap)
	return -ENOMEM;
	cma_heap->cma = cma;

	exp_info.name = cma_get_name(cma);
	exp_info.ops = &cma_heap_ops;
	exp_info.priv = cma_heap;

	cma_heap->heap = dma_heap_add(&exp_info);
	if (IS_ERR(cma_heap->heap)) {
	int ret = PTR_ERR(cma_heap->heap);

	kfree(cma_heap);
	return ret;
	}

	return 0;
	}

	static int add_default_cma_heap(void)
	{
	struct cma *default_cma = dev_get_cma_area(NULL);
	int ret = 0;

	if (default_cma)
	ret = __add_cma_heap(default_cma, NULL);

	return ret;
	}
	module_init(add_default_cma_heap);
	MODULE_DESCRIPTION("DMA-BUF CMA Heap");