drivers/fpga/dfl-afu-dma-region.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Driver for FPGA Accelerated Function Unit (AFU) DMA Region Management
  *
  * Copyright (C) 2017-2018 Intel Corporation, Inc.
  *
  * Authors:
  *   Wu Hao <hao.wu@intel.com>
  *   Xiao Guangrong <guangrong.xiao@linux.intel.com>
  */

 #include <linux/dma-mapping.h>
 #include <linux/sched/signal.h>
 #include <linux/uaccess.h>

 #include "dfl-afu.h"

 static void put_all_pages(struct page **pages, int npages)
 {
 	int i;

 	for (i = 0; i < npages; i++)
 		if (pages[i])
 			put_page(pages[i]);
 }

 void afu_dma_region_init(struct dfl_feature_platform_data *pdata)
 {
 	struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);

 	afu->dma_regions = RB_ROOT;
 }

 /**
  * afu_dma_adjust_locked_vm - adjust locked memory
  * @dev: port device
  * @npages: number of pages
  * @incr: increase or decrease locked memory
  *
  * Increase or decrease the locked memory size with npages input.
  *
  * Return 0 on success.
  * Return -ENOMEM if locked memory size is over the limit and no CAP_IPC_LOCK.
  */
 static int afu_dma_adjust_locked_vm(struct device *dev, long npages, bool incr)
 {
 	unsigned long locked, lock_limit;
 	int ret = 0;

 	/* the task is exiting. */
 	if (!current->mm)
 		return 0;

 	down_write(&current->mm->mmap_sem);

 	if (incr) {
 		locked = current->mm->locked_vm + npages;
 		lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;

 		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
 			ret = -ENOMEM;
 		else
 			current->mm->locked_vm += npages;
 	} else {
 		if (WARN_ON_ONCE(npages > current->mm->locked_vm))
 			npages = current->mm->locked_vm;
 		current->mm->locked_vm -= npages;
 	}

 	dev_dbg(dev, "[%d] RLIMIT_MEMLOCK %c%ld %ld/%ld%s\n", current->pid,
 		incr ? '+' : '-', npages << PAGE_SHIFT,
 		current->mm->locked_vm << PAGE_SHIFT, rlimit(RLIMIT_MEMLOCK),
 		ret ? "- exceeded" : "");

 	up_write(&current->mm->mmap_sem);

 	return ret;
 }

 /**
  * afu_dma_pin_pages - pin pages of given dma memory region
  * @pdata: feature device platform data
  * @region: dma memory region to be pinned
  *
  * Pin all the pages of given dfl_afu_dma_region.
  * Return 0 for success or negative error code.
  */
 static int afu_dma_pin_pages(struct dfl_feature_platform_data *pdata,
 			     struct dfl_afu_dma_region *region)
 {
 	int npages = region->length >> PAGE_SHIFT;
 	struct device *dev = &pdata->dev->dev;
 	int ret, pinned;

 	ret = afu_dma_adjust_locked_vm(dev, npages, true);
 	if (ret)
 		return ret;

 	region->pages = kcalloc(npages, sizeof(struct page *), GFP_KERNEL);
 	if (!region->pages) {
 		ret = -ENOMEM;
 		goto unlock_vm;
 	}

 	pinned = get_user_pages_fast(region->user_addr, npages, FOLL_WRITE,
 				     region->pages);
 	if (pinned < 0) {
 		ret = pinned;
 		goto put_pages;
 	} else if (pinned != npages) {
 		ret = -EFAULT;
 		goto free_pages;
 	}

 	dev_dbg(dev, "%d pages pinned\n", pinned);

 	return 0;

 put_pages:
 	put_all_pages(region->pages, pinned);
 free_pages:
 	kfree(region->pages);
 unlock_vm:
 	afu_dma_adjust_locked_vm(dev, npages, false);
 	return ret;
 }

 /**
  * afu_dma_unpin_pages - unpin pages of given dma memory region
  * @pdata: feature device platform data
  * @region: dma memory region to be unpinned
  *
  * Unpin all the pages of given dfl_afu_dma_region.
  * Return 0 for success or negative error code.
  */
 static void afu_dma_unpin_pages(struct dfl_feature_platform_data *pdata,
 				struct dfl_afu_dma_region *region)
 {
 	long npages = region->length >> PAGE_SHIFT;
 	struct device *dev = &pdata->dev->dev;

 	put_all_pages(region->pages, npages);
 	kfree(region->pages);
 	afu_dma_adjust_locked_vm(dev, npages, false);

 	dev_dbg(dev, "%ld pages unpinned\n", npages);
 }

 /**
  * afu_dma_check_continuous_pages - check if pages are continuous
  * @region: dma memory region
  *
  * Return true if pages of given dma memory region have continuous physical
  * address, otherwise return false.
  */
 static bool afu_dma_check_continuous_pages(struct dfl_afu_dma_region *region)
 {
 	int npages = region->length >> PAGE_SHIFT;
 	int i;

 	for (i = 0; i < npages - 1; i++)
 		if (page_to_pfn(region->pages[i]) + 1 !=
 				page_to_pfn(region->pages[i + 1]))
 			return false;

 	return true;
 }

 /**
  * dma_region_check_iova - check if memory area is fully contained in the region
  * @region: dma memory region
  * @iova: address of the dma memory area
  * @size: size of the dma memory area
  *
  * Compare the dma memory area defined by @iova and @size with given dma region.
  * Return true if memory area is fully contained in the region, otherwise false.
  */
 static bool dma_region_check_iova(struct dfl_afu_dma_region *region,
 				  u64 iova, u64 size)
 {
 	if (!size && region->iova != iova)
 		return false;

 	return (region->iova <= iova) &&
 		(region->length + region->iova >= iova + size);
 }

 /**
  * afu_dma_region_add - add given dma region to rbtree
  * @pdata: feature device platform data
  * @region: dma region to be added
  *
  * Return 0 for success, -EEXIST if dma region has already been added.
  *
  * Needs to be called with pdata->lock heold.
  */
 static int afu_dma_region_add(struct dfl_feature_platform_data *pdata,
 			      struct dfl_afu_dma_region *region)
 {
 	struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
 	struct rb_node **new, *parent = NULL;

 	dev_dbg(&pdata->dev->dev, "add region (iova = %llx)\n",
 		(unsigned long long)region->iova);

 	new = &afu->dma_regions.rb_node;

 	while (*new) {
 		struct dfl_afu_dma_region *this;

 		this = container_of(*new, struct dfl_afu_dma_region, node);

 		parent = *new;

 		if (dma_region_check_iova(this, region->iova, region->length))
 			return -EEXIST;

 		if (region->iova < this->iova)
 			new = &((*new)->rb_left);
 		else if (region->iova > this->iova)
 			new = &((*new)->rb_right);
 		else
 			return -EEXIST;
 	}

 	rb_link_node(&region->node, parent, new);
 	rb_insert_color(&region->node, &afu->dma_regions);

 	return 0;
 }

 /**
  * afu_dma_region_remove - remove given dma region from rbtree
  * @pdata: feature device platform data
  * @region: dma region to be removed
  *
  * Needs to be called with pdata->lock heold.
  */
 static void afu_dma_region_remove(struct dfl_feature_platform_data *pdata,
 				  struct dfl_afu_dma_region *region)
 {
 	struct dfl_afu *afu;

 	dev_dbg(&pdata->dev->dev, "del region (iova = %llx)\n",
 		(unsigned long long)region->iova);

 	afu = dfl_fpga_pdata_get_private(pdata);
 	rb_erase(&region->node, &afu->dma_regions);
 }

 /**
  * afu_dma_region_destroy - destroy all regions in rbtree
  * @pdata: feature device platform data
  *
  * Needs to be called with pdata->lock heold.
  */
 void afu_dma_region_destroy(struct dfl_feature_platform_data *pdata)
 {
 	struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
 	struct rb_node *node = rb_first(&afu->dma_regions);
 	struct dfl_afu_dma_region *region;

 	while (node) {
 		region = container_of(node, struct dfl_afu_dma_region, node);

 		dev_dbg(&pdata->dev->dev, "del region (iova = %llx)\n",
 			(unsigned long long)region->iova);

 		rb_erase(node, &afu->dma_regions);

 		if (region->iova)
 			dma_unmap_page(dfl_fpga_pdata_to_parent(pdata),
 				       region->iova, region->length,
 				       DMA_BIDIRECTIONAL);

 		if (region->pages)
 			afu_dma_unpin_pages(pdata, region);

 		node = rb_next(node);
 		kfree(region);
 	}
 }

 /**
  * afu_dma_region_find - find the dma region from rbtree based on iova and size
  * @pdata: feature device platform data
  * @iova: address of the dma memory area
  * @size: size of the dma memory area
  *
  * It finds the dma region from the rbtree based on @iova and @size:
  * - if @size == 0, it finds the dma region which starts from @iova
  * - otherwise, it finds the dma region which fully contains
  *   [@iova, @iova+size)
  * If nothing is matched returns NULL.
  *
  * Needs to be called with pdata->lock held.
  */
 struct dfl_afu_dma_region *
 afu_dma_region_find(struct dfl_feature_platform_data *pdata, u64 iova, u64 size)
 {
 	struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
 	struct rb_node *node = afu->dma_regions.rb_node;
 	struct device *dev = &pdata->dev->dev;

 	while (node) {
 		struct dfl_afu_dma_region *region;

 		region = container_of(node, struct dfl_afu_dma_region, node);

 		if (dma_region_check_iova(region, iova, size)) {
 			dev_dbg(dev, "find region (iova = %llx)\n",
 				(unsigned long long)region->iova);
 			return region;
 		}

 		if (iova < region->iova)
 			node = node->rb_left;
 		else if (iova > region->iova)
 			node = node->rb_right;
 		else
 			/* the iova region is not fully covered. */
 			break;
 	}

 	dev_dbg(dev, "region with iova %llx and size %llx is not found\n",
 		(unsigned long long)iova, (unsigned long long)size);

 	return NULL;
 }

 /**
  * afu_dma_region_find_iova - find the dma region from rbtree by iova
  * @pdata: feature device platform data
  * @iova: address of the dma region
  *
  * Needs to be called with pdata->lock held.
  */
 static struct dfl_afu_dma_region *
 afu_dma_region_find_iova(struct dfl_feature_platform_data *pdata, u64 iova)
 {
 	return afu_dma_region_find(pdata, iova, 0);
 }

 /**
  * afu_dma_map_region - map memory region for dma
  * @pdata: feature device platform data
  * @user_addr: address of the memory region
  * @length: size of the memory region
  * @iova: pointer of iova address
  *
  * Map memory region defined by @user_addr and @length, and return dma address
  * of the memory region via @iova.
  * Return 0 for success, otherwise error code.
  */
 int afu_dma_map_region(struct dfl_feature_platform_data *pdata,
 		       u64 user_addr, u64 length, u64 *iova)
 {
 	struct dfl_afu_dma_region *region;
 	int ret;

 	/*
 	 * Check Inputs, only accept page-aligned user memory region with
 	 * valid length.
 	 */
 	if (!PAGE_ALIGNED(user_addr) || !PAGE_ALIGNED(length) || !length)
 		return -EINVAL;

 	/* Check overflow */
 	if (user_addr + length < user_addr)
 		return -EINVAL;

 	if (!access_ok((void __user *)(unsigned long)user_addr,
 		       length))
 		return -EINVAL;

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

 	region->user_addr = user_addr;
 	region->length = length;

 	/* Pin the user memory region */
 	ret = afu_dma_pin_pages(pdata, region);
 	if (ret) {
 		dev_err(&pdata->dev->dev, "failed to pin memory region\n");
 		goto free_region;
 	}

 	/* Only accept continuous pages, return error else */
 	if (!afu_dma_check_continuous_pages(region)) {
 		dev_err(&pdata->dev->dev, "pages are not continuous\n");
 		ret = -EINVAL;
 		goto unpin_pages;
 	}

 	/* As pages are continuous then start to do DMA mapping */
 	region->iova = dma_map_page(dfl_fpga_pdata_to_parent(pdata),
 				    region->pages[0], 0,
 				    region->length,
 				    DMA_BIDIRECTIONAL);
 	if (dma_mapping_error(dfl_fpga_pdata_to_parent(pdata), region->iova)) {
 		dev_err(&pdata->dev->dev, "failed to map for dma\n");
 		ret = -EFAULT;
 		goto unpin_pages;
 	}

 	*iova = region->iova;

 	mutex_lock(&pdata->lock);
 	ret = afu_dma_region_add(pdata, region);
 	mutex_unlock(&pdata->lock);
 	if (ret) {
 		dev_err(&pdata->dev->dev, "failed to add dma region\n");
 		goto unmap_dma;
 	}

 	return 0;

 unmap_dma:
 	dma_unmap_page(dfl_fpga_pdata_to_parent(pdata),
 		       region->iova, region->length, DMA_BIDIRECTIONAL);
 unpin_pages:
 	afu_dma_unpin_pages(pdata, region);
 free_region:
 	kfree(region);
 	return ret;
 }

 /**
  * afu_dma_unmap_region - unmap dma memory region
  * @pdata: feature device platform data
  * @iova: dma address of the region
  *
  * Unmap dma memory region based on @iova.
  * Return 0 for success, otherwise error code.
  */
 int afu_dma_unmap_region(struct dfl_feature_platform_data *pdata, u64 iova)
 {
 	struct dfl_afu_dma_region *region;

 	mutex_lock(&pdata->lock);
 	region = afu_dma_region_find_iova(pdata, iova);
 	if (!region) {
 		mutex_unlock(&pdata->lock);
 		return -EINVAL;
 	}

 	if (region->in_use) {
 		mutex_unlock(&pdata->lock);
 		return -EBUSY;
 	}

 	afu_dma_region_remove(pdata, region);
 	mutex_unlock(&pdata->lock);

 	dma_unmap_page(dfl_fpga_pdata_to_parent(pdata),
 		       region->iova, region->length, DMA_BIDIRECTIONAL);
 	afu_dma_unpin_pages(pdata, region);
 	kfree(region);

 	return 0;
 }
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Driver for FPGA Accelerated Function Unit (AFU) DMA Region Management
	*
	* Copyright (C) 2017-2018 Intel Corporation, Inc.
	*
	* Authors:
	* Wu Hao <hao.wu@intel.com>
	* Xiao Guangrong <guangrong.xiao@linux.intel.com>
	*/

	#include <linux/dma-mapping.h>
	#include <linux/sched/signal.h>
	#include <linux/uaccess.h>

	#include "dfl-afu.h"

	static void put_all_pages(struct page **pages, int npages)
	{
	int i;

	for (i = 0; i < npages; i++)
	if (pages[i])
	put_page(pages[i]);
	}

	void afu_dma_region_init(struct dfl_feature_platform_data *pdata)
	{
	struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);

	afu->dma_regions = RB_ROOT;
	}

	/**
	* afu_dma_adjust_locked_vm - adjust locked memory
	* @dev: port device
	* @npages: number of pages
	* @incr: increase or decrease locked memory
	*
	* Increase or decrease the locked memory size with npages input.
	*
	* Return 0 on success.
	* Return -ENOMEM if locked memory size is over the limit and no CAP_IPC_LOCK.
	*/
	static int afu_dma_adjust_locked_vm(struct device *dev, long npages, bool incr)
	{
	unsigned long locked, lock_limit;
	int ret = 0;

	/* the task is exiting. */
	if (!current->mm)
	return 0;

	down_write(&current->mm->mmap_sem);

	if (incr) {
	locked = current->mm->locked_vm + npages;
	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;

	if (locked > lock_limit && !capable(CAP_IPC_LOCK))
	ret = -ENOMEM;
	else
	current->mm->locked_vm += npages;
	} else {
	if (WARN_ON_ONCE(npages > current->mm->locked_vm))
	npages = current->mm->locked_vm;
	current->mm->locked_vm -= npages;
	}

	dev_dbg(dev, "[%d] RLIMIT_MEMLOCK %c%ld %ld/%ld%s\n", current->pid,
	incr ? '+' : '-', npages << PAGE_SHIFT,
	current->mm->locked_vm << PAGE_SHIFT, rlimit(RLIMIT_MEMLOCK),
	ret ? "- exceeded" : "");

	up_write(&current->mm->mmap_sem);

	return ret;
	}

	/**
	* afu_dma_pin_pages - pin pages of given dma memory region
	* @pdata: feature device platform data
	* @region: dma memory region to be pinned
	*
	* Pin all the pages of given dfl_afu_dma_region.
	* Return 0 for success or negative error code.
	*/
	static int afu_dma_pin_pages(struct dfl_feature_platform_data *pdata,
	struct dfl_afu_dma_region *region)
	{
	int npages = region->length >> PAGE_SHIFT;
	struct device *dev = &pdata->dev->dev;
	int ret, pinned;

	ret = afu_dma_adjust_locked_vm(dev, npages, true);
	if (ret)
	return ret;

	region->pages = kcalloc(npages, sizeof(struct page *), GFP_KERNEL);
	if (!region->pages) {
	ret = -ENOMEM;
	goto unlock_vm;
	}

	pinned = get_user_pages_fast(region->user_addr, npages, FOLL_WRITE,
	region->pages);
	if (pinned < 0) {
	ret = pinned;
	goto put_pages;
	} else if (pinned != npages) {
	ret = -EFAULT;
	goto free_pages;
	}

	dev_dbg(dev, "%d pages pinned\n", pinned);

	return 0;

	put_pages:
	put_all_pages(region->pages, pinned);
	free_pages:
	kfree(region->pages);
	unlock_vm:
	afu_dma_adjust_locked_vm(dev, npages, false);
	return ret;
	}

	/**
	* afu_dma_unpin_pages - unpin pages of given dma memory region
	* @pdata: feature device platform data
	* @region: dma memory region to be unpinned
	*
	* Unpin all the pages of given dfl_afu_dma_region.
	* Return 0 for success or negative error code.
	*/
	static void afu_dma_unpin_pages(struct dfl_feature_platform_data *pdata,
	struct dfl_afu_dma_region *region)
	{
	long npages = region->length >> PAGE_SHIFT;
	struct device *dev = &pdata->dev->dev;

	put_all_pages(region->pages, npages);
	kfree(region->pages);
	afu_dma_adjust_locked_vm(dev, npages, false);

	dev_dbg(dev, "%ld pages unpinned\n", npages);
	}

	/**
	* afu_dma_check_continuous_pages - check if pages are continuous
	* @region: dma memory region
	*
	* Return true if pages of given dma memory region have continuous physical
	* address, otherwise return false.
	*/
	static bool afu_dma_check_continuous_pages(struct dfl_afu_dma_region *region)
	{
	int npages = region->length >> PAGE_SHIFT;
	int i;

	for (i = 0; i < npages - 1; i++)
	if (page_to_pfn(region->pages[i]) + 1 !=
	page_to_pfn(region->pages[i + 1]))
	return false;

	return true;
	}

	/**
	* dma_region_check_iova - check if memory area is fully contained in the region
	* @region: dma memory region
	* @iova: address of the dma memory area
	* @size: size of the dma memory area
	*
	* Compare the dma memory area defined by @iova and @size with given dma region.
	* Return true if memory area is fully contained in the region, otherwise false.
	*/
	static bool dma_region_check_iova(struct dfl_afu_dma_region *region,
	u64 iova, u64 size)
	{
	if (!size && region->iova != iova)
	return false;

	return (region->iova <= iova) &&
	(region->length + region->iova >= iova + size);
	}

	/**
	* afu_dma_region_add - add given dma region to rbtree
	* @pdata: feature device platform data
	* @region: dma region to be added
	*
	* Return 0 for success, -EEXIST if dma region has already been added.
	*
	* Needs to be called with pdata->lock heold.
	*/
	static int afu_dma_region_add(struct dfl_feature_platform_data *pdata,
	struct dfl_afu_dma_region *region)
	{
	struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
	struct rb_node *new, parent = NULL;

	dev_dbg(&pdata->dev->dev, "add region (iova = %llx)\n",
	(unsigned long long)region->iova);

	new = &afu->dma_regions.rb_node;

	while (*new) {
	struct dfl_afu_dma_region *this;

	this = container_of(*new, struct dfl_afu_dma_region, node);

	parent = *new;

	if (dma_region_check_iova(this, region->iova, region->length))
	return -EEXIST;

	if (region->iova < this->iova)
	new = &((*new)->rb_left);
	else if (region->iova > this->iova)
	new = &((*new)->rb_right);
	else
	return -EEXIST;
	}

	rb_link_node(&region->node, parent, new);
	rb_insert_color(&region->node, &afu->dma_regions);

	return 0;
	}

	/**
	* afu_dma_region_remove - remove given dma region from rbtree
	* @pdata: feature device platform data
	* @region: dma region to be removed
	*
	* Needs to be called with pdata->lock heold.
	*/
	static void afu_dma_region_remove(struct dfl_feature_platform_data *pdata,
	struct dfl_afu_dma_region *region)
	{
	struct dfl_afu *afu;

	dev_dbg(&pdata->dev->dev, "del region (iova = %llx)\n",
	(unsigned long long)region->iova);

	afu = dfl_fpga_pdata_get_private(pdata);
	rb_erase(&region->node, &afu->dma_regions);
	}

	/**
	* afu_dma_region_destroy - destroy all regions in rbtree
	* @pdata: feature device platform data
	*
	* Needs to be called with pdata->lock heold.
	*/
	void afu_dma_region_destroy(struct dfl_feature_platform_data *pdata)
	{
	struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
	struct rb_node *node = rb_first(&afu->dma_regions);
	struct dfl_afu_dma_region *region;

	while (node) {
	region = container_of(node, struct dfl_afu_dma_region, node);

	dev_dbg(&pdata->dev->dev, "del region (iova = %llx)\n",
	(unsigned long long)region->iova);

	rb_erase(node, &afu->dma_regions);

	if (region->iova)
	dma_unmap_page(dfl_fpga_pdata_to_parent(pdata),
	region->iova, region->length,
	DMA_BIDIRECTIONAL);

	if (region->pages)
	afu_dma_unpin_pages(pdata, region);

	node = rb_next(node);
	kfree(region);
	}
	}

	/**
	* afu_dma_region_find - find the dma region from rbtree based on iova and size
	* @pdata: feature device platform data
	* @iova: address of the dma memory area
	* @size: size of the dma memory area
	*
	* It finds the dma region from the rbtree based on @iova and @size:
	* - if @size == 0, it finds the dma region which starts from @iova
	* - otherwise, it finds the dma region which fully contains
	* [@iova, @iova+size)
	* If nothing is matched returns NULL.
	*
	* Needs to be called with pdata->lock held.
	*/
	struct dfl_afu_dma_region *
	afu_dma_region_find(struct dfl_feature_platform_data *pdata, u64 iova, u64 size)
	{
	struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
	struct rb_node *node = afu->dma_regions.rb_node;
	struct device *dev = &pdata->dev->dev;

	while (node) {
	struct dfl_afu_dma_region *region;

	region = container_of(node, struct dfl_afu_dma_region, node);

	if (dma_region_check_iova(region, iova, size)) {
	dev_dbg(dev, "find region (iova = %llx)\n",
	(unsigned long long)region->iova);
	return region;
	}

	if (iova < region->iova)
	node = node->rb_left;
	else if (iova > region->iova)
	node = node->rb_right;
	else
	/* the iova region is not fully covered. */
	break;
	}

	dev_dbg(dev, "region with iova %llx and size %llx is not found\n",
	(unsigned long long)iova, (unsigned long long)size);

	return NULL;
	}

	/**
	* afu_dma_region_find_iova - find the dma region from rbtree by iova
	* @pdata: feature device platform data
	* @iova: address of the dma region
	*
	* Needs to be called with pdata->lock held.
	*/
	static struct dfl_afu_dma_region *
	afu_dma_region_find_iova(struct dfl_feature_platform_data *pdata, u64 iova)
	{
	return afu_dma_region_find(pdata, iova, 0);
	}

	/**
	* afu_dma_map_region - map memory region for dma
	* @pdata: feature device platform data
	* @user_addr: address of the memory region
	* @length: size of the memory region
	* @iova: pointer of iova address
	*
	* Map memory region defined by @user_addr and @length, and return dma address
	* of the memory region via @iova.
	* Return 0 for success, otherwise error code.
	*/
	int afu_dma_map_region(struct dfl_feature_platform_data *pdata,
	u64 user_addr, u64 length, u64 *iova)
	{
	struct dfl_afu_dma_region *region;
	int ret;

	/*
	* Check Inputs, only accept page-aligned user memory region with
	* valid length.
	*/
	if (!PAGE_ALIGNED(user_addr) \|\| !PAGE_ALIGNED(length) \|\| !length)
	return -EINVAL;

	/* Check overflow */
	if (user_addr + length < user_addr)
	return -EINVAL;

	if (!access_ok((void __user *)(unsigned long)user_addr,
	length))
	return -EINVAL;

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

	region->user_addr = user_addr;
	region->length = length;

	/* Pin the user memory region */
	ret = afu_dma_pin_pages(pdata, region);
	if (ret) {
	dev_err(&pdata->dev->dev, "failed to pin memory region\n");
	goto free_region;
	}

	/* Only accept continuous pages, return error else */
	if (!afu_dma_check_continuous_pages(region)) {
	dev_err(&pdata->dev->dev, "pages are not continuous\n");
	ret = -EINVAL;
	goto unpin_pages;
	}

	/* As pages are continuous then start to do DMA mapping */
	region->iova = dma_map_page(dfl_fpga_pdata_to_parent(pdata),
	region->pages[0], 0,
	region->length,
	DMA_BIDIRECTIONAL);
	if (dma_mapping_error(dfl_fpga_pdata_to_parent(pdata), region->iova)) {
	dev_err(&pdata->dev->dev, "failed to map for dma\n");
	ret = -EFAULT;
	goto unpin_pages;
	}

	*iova = region->iova;

	mutex_lock(&pdata->lock);
	ret = afu_dma_region_add(pdata, region);
	mutex_unlock(&pdata->lock);
	if (ret) {
	dev_err(&pdata->dev->dev, "failed to add dma region\n");
	goto unmap_dma;
	}

	return 0;

	unmap_dma:
	dma_unmap_page(dfl_fpga_pdata_to_parent(pdata),
	region->iova, region->length, DMA_BIDIRECTIONAL);
	unpin_pages:
	afu_dma_unpin_pages(pdata, region);
	free_region:
	kfree(region);
	return ret;
	}

	/**
	* afu_dma_unmap_region - unmap dma memory region
	* @pdata: feature device platform data
	* @iova: dma address of the region
	*
	* Unmap dma memory region based on @iova.
	* Return 0 for success, otherwise error code.
	*/
	int afu_dma_unmap_region(struct dfl_feature_platform_data *pdata, u64 iova)
	{
	struct dfl_afu_dma_region *region;

	mutex_lock(&pdata->lock);
	region = afu_dma_region_find_iova(pdata, iova);
	if (!region) {
	mutex_unlock(&pdata->lock);
	return -EINVAL;
	}

	if (region->in_use) {
	mutex_unlock(&pdata->lock);
	return -EBUSY;
	}

	afu_dma_region_remove(pdata, region);
	mutex_unlock(&pdata->lock);

	dma_unmap_page(dfl_fpga_pdata_to_parent(pdata),
	region->iova, region->length, DMA_BIDIRECTIONAL);
	afu_dma_unpin_pages(pdata, region);
	kfree(region);

	return 0;
	}