[PATCH v7 27/29] fpga: dfl: afu: add afu sub feature support

[Wu Hao <hao.wu@intel.com>]

From: Xiao Guangrong <guangrong.xiao@linux.intel.com>

User Accelerated Function Unit sub feature exposes the MMIO region of
the AFU. After valid PR bitstream is programmed and the port is enabled,
then this MMIO region could be accessed.

This patch adds support to enumerate the AFU MMIO region and expose it
to userspace via mmap file operation. Below interfaces are exposed to user:

Sysfs interface:
* /sys/class/fpga_region/<regionX>/<dfl-port.x>/afu_id
  Read-only. Indicate which PR bitstream is programmed to this AFU.

Ioctl interfaces:
* DFL_FPGA_PORT_GET_INFO
  Provide info to userspace on the number of supported region.
  Only UAFU region is supported now.

* DFL_FPGA_PORT_GET_REGION_INFO
  Provide region information, including access permission, region size,
  offset from the start of device fd.

Signed-off-by: Tim Whisonant <tim.whisonant@intel.com>
Signed-off-by: Enno Luebbers <enno.luebbers@intel.com>
Signed-off-by: Shiva Rao <shiva.rao@intel.com>
Signed-off-by: Christopher Rauer <christopher.rauer@intel.com>
Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Wu Hao <hao.wu@intel.com>
Acked-by: Alan Tull <atull@kernel.org>
---
v2: moved the code to drivers/fpga folder as suggested by Alan Tull.
    switched to GPLv2 license.
    fixed kbuild warnings.
v3: improved commit description and fixed coding style issues.
    replaced fpga_pdata_to_pcidev with fpga_pdata_to_fpga_cdev
v4: rebase and fix SPDX license issue
v5: rebase, due to DFL framework naming changes.
    add DFL_ prefix to IOCTL API.
    remove "user" afu and replace "green bitstream" terminology.
    add "mmio" to afu region functions and data structures.
v6: rebase, fix copyright time and add Acked-by Alan.
v7: update kernelversion in sysfs doc and fix typos.
---
 Documentation/ABI/testing/sysfs-platform-dfl-port |   9 +
 drivers/fpga/Makefile                             |   2 +-
 drivers/fpga/dfl-afu-main.c                       | 219 +++++++++++++++++++++-
 drivers/fpga/dfl-afu-region.c                     | 166 ++++++++++++++++
 drivers/fpga/dfl-afu.h                            |  71 +++++++
 include/uapi/linux/fpga-dfl.h                     |  48 +++++
 6 files changed, 508 insertions(+), 7 deletions(-)
 create mode 100644 drivers/fpga/dfl-afu-region.c
 create mode 100644 drivers/fpga/dfl-afu.h

diff --git a/Documentation/ABI/testing/sysfs-platform-dfl-port b/Documentation/ABI/testing/sysfs-platform-dfl-port
index cb91165..6a92dda 100644
--- a/Documentation/ABI/testing/sysfs-platform-dfl-port
+++ b/Documentation/ABI/testing/sysfs-platform-dfl-port
@@ -5,3 +5,12 @@ Contact:	Wu Hao <hao.wu@intel.com>
 Description:	Read-only. It returns id of this port. One DFL FPGA device
 		may have more than one port. Userspace could use this id to
 		distinguish different ports under same FPGA device.
+
+What:		/sys/bus/platform/devices/dfl-port.0/afu_id
+Date:		June 2018
+KernelVersion:	4.19
+Contact:	Wu Hao <hao.wu@intel.com>
+Description:	Read-only. User can program different PR bitstreams to FPGA
+		Accelerator Function Unit (AFU) for different functions. It
+		returns uuid which could be used to identify which PR bitstream
+		is programmed in this AFU.
diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
index 1ac7749..a44d50d 100644
--- a/drivers/fpga/Makefile
+++ b/drivers/fpga/Makefile
@@ -38,7 +38,7 @@ obj-$(CONFIG_FPGA_DFL_FME_REGION)	+= dfl-fme-region.o
 obj-$(CONFIG_FPGA_DFL_AFU)		+= dfl-afu.o
 
 dfl-fme-objs := dfl-fme-main.o dfl-fme-pr.o
-dfl-afu-objs := dfl-afu-main.o
+dfl-afu-objs := dfl-afu-main.o dfl-afu-region.o
 
 # Drivers for FPGAs which implement DFL
 obj-$(CONFIG_FPGA_DFL_PCI)		+= dfl-pci.o
diff --git a/drivers/fpga/dfl-afu-main.c b/drivers/fpga/dfl-afu-main.c
index 4074b97..f67a78d 100644
--- a/drivers/fpga/dfl-afu-main.c
+++ b/drivers/fpga/dfl-afu-main.c
@@ -16,18 +16,18 @@
 
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/uaccess.h>
 #include <linux/fpga-dfl.h>
 
-#include "dfl.h"
+#include "dfl-afu.h"
 
 /**
  * port_enable - enable a port
  * @pdev: port platform device.
  *
  * Enable Port by clear the port soft reset bit, which is set by default.
- * The User AFU is unable to respond to any MMIO access while in reset.
- * port_enable function should only be used after port_disable
- * function.
+ * The AFU is unable to respond to any MMIO access while in reset.
+ * port_enable function should only be used after port_disable function.
  */
 static void port_enable(struct platform_device *pdev)
 {
@@ -191,12 +191,75 @@ static void port_hdr_uinit(struct platform_device *pdev,
 	.ioctl = port_hdr_ioctl,
 };
 
+static ssize_t
+afu_id_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct dfl_feature_platform_data *pdata = dev_get_platdata(dev);
+	void __iomem *base;
+	u64 guidl, guidh;
+
+	base = dfl_get_feature_ioaddr_by_id(dev, PORT_FEATURE_ID_AFU);
+
+	mutex_lock(&pdata->lock);
+	if (pdata->disable_count) {
+		mutex_unlock(&pdata->lock);
+		return -EBUSY;
+	}
+
+	guidl = readq(base + GUID_L);
+	guidh = readq(base + GUID_H);
+	mutex_unlock(&pdata->lock);
+
+	return scnprintf(buf, PAGE_SIZE, "%016llx%016llx\n", guidh, guidl);
+}
+static DEVICE_ATTR_RO(afu_id);
+
+static const struct attribute *port_afu_attrs[] = {
+	&dev_attr_afu_id.attr,
+	NULL
+};
+
+static int port_afu_init(struct platform_device *pdev,
+			 struct dfl_feature *feature)
+{
+	struct resource *res = &pdev->resource[feature->resource_index];
+	int ret;
+
+	dev_dbg(&pdev->dev, "PORT AFU Init.\n");
+
+	ret = afu_mmio_region_add(dev_get_platdata(&pdev->dev),
+				  DFL_PORT_REGION_INDEX_AFU, resource_size(res),
+				  res->start, DFL_PORT_REGION_READ |
+				  DFL_PORT_REGION_WRITE | DFL_PORT_REGION_MMAP);
+	if (ret)
+		return ret;
+
+	return sysfs_create_files(&pdev->dev.kobj, port_afu_attrs);
+}
+
+static void port_afu_uinit(struct platform_device *pdev,
+			   struct dfl_feature *feature)
+{
+	dev_dbg(&pdev->dev, "PORT AFU UInit.\n");
+
+	sysfs_remove_files(&pdev->dev.kobj, port_afu_attrs);
+}
+
+static const struct dfl_feature_ops port_afu_ops = {
+	.init = port_afu_init,
+	.uinit = port_afu_uinit,
+};
+
 static struct dfl_feature_driver port_feature_drvs[] = {
 	{
 		.id = PORT_FEATURE_ID_HEADER,
 		.ops = &port_hdr_ops,
 	},
 	{
+		.id = PORT_FEATURE_ID_AFU,
+		.ops = &port_afu_ops,
+	},
+	{
 		.ops = NULL,
 	}
 };
@@ -243,6 +306,64 @@ static long afu_ioctl_check_extension(struct dfl_feature_platform_data *pdata,
 	return 0;
 }
 
+static long
+afu_ioctl_get_info(struct dfl_feature_platform_data *pdata, void __user *arg)
+{
+	struct dfl_fpga_port_info info;
+	struct dfl_afu *afu;
+	unsigned long minsz;
+
+	minsz = offsetofend(struct dfl_fpga_port_info, num_umsgs);
+
+	if (copy_from_user(&info, arg, minsz))
+		return -EFAULT;
+
+	if (info.argsz < minsz)
+		return -EINVAL;
+
+	mutex_lock(&pdata->lock);
+	afu = dfl_fpga_pdata_get_private(pdata);
+	info.flags = 0;
+	info.num_regions = afu->num_regions;
+	info.num_umsgs = afu->num_umsgs;
+	mutex_unlock(&pdata->lock);
+
+	if (copy_to_user(arg, &info, sizeof(info)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static long afu_ioctl_get_region_info(struct dfl_feature_platform_data *pdata,
+				      void __user *arg)
+{
+	struct dfl_fpga_port_region_info rinfo;
+	struct dfl_afu_mmio_region region;
+	unsigned long minsz;
+	long ret;
+
+	minsz = offsetofend(struct dfl_fpga_port_region_info, offset);
+
+	if (copy_from_user(&rinfo, arg, minsz))
+		return -EFAULT;
+
+	if (rinfo.argsz < minsz || rinfo.padding)
+		return -EINVAL;
+
+	ret = afu_mmio_region_get_by_index(pdata, rinfo.index, &region);
+	if (ret)
+		return ret;
+
+	rinfo.flags = region.flags;
+	rinfo.size = region.size;
+	rinfo.offset = region.offset;
+
+	if (copy_to_user(arg, &rinfo, sizeof(rinfo)))
+		return -EFAULT;
+
+	return 0;
+}
+
 static long afu_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
 	struct platform_device *pdev = filp->private_data;
@@ -259,6 +380,10 @@ static long afu_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 		return DFL_FPGA_API_VERSION;
 	case DFL_FPGA_CHECK_EXTENSION:
 		return afu_ioctl_check_extension(pdata, arg);
+	case DFL_FPGA_PORT_GET_INFO:
+		return afu_ioctl_get_info(pdata, (void __user *)arg);
+	case DFL_FPGA_PORT_GET_REGION_INFO:
+		return afu_ioctl_get_region_info(pdata, (void __user *)arg);
 	default:
 		/*
 		 * Let sub-feature's ioctl function to handle the cmd
@@ -277,13 +402,83 @@ static long afu_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	return -EINVAL;
 }
 
+static int afu_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+	struct platform_device *pdev = filp->private_data;
+	struct dfl_feature_platform_data *pdata;
+	u64 size = vma->vm_end - vma->vm_start;
+	struct dfl_afu_mmio_region region;
+	u64 offset;
+	int ret;
+
+	if (!(vma->vm_flags & VM_SHARED))
+		return -EINVAL;
+
+	pdata = dev_get_platdata(&pdev->dev);
+
+	offset = vma->vm_pgoff << PAGE_SHIFT;
+	ret = afu_mmio_region_get_by_offset(pdata, offset, size, &region);
+	if (ret)
+		return ret;
+
+	if (!(region.flags & DFL_PORT_REGION_MMAP))
+		return -EINVAL;
+
+	if ((vma->vm_flags & VM_READ) && !(region.flags & DFL_PORT_REGION_READ))
+		return -EPERM;
+
+	if ((vma->vm_flags & VM_WRITE) &&
+	    !(region.flags & DFL_PORT_REGION_WRITE))
+		return -EPERM;
+
+	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+
+	return remap_pfn_range(vma, vma->vm_start,
+			(region.phys + (offset - region.offset)) >> PAGE_SHIFT,
+			size, vma->vm_page_prot);
+}
+
 static const struct file_operations afu_fops = {
 	.owner = THIS_MODULE,
 	.open = afu_open,
 	.release = afu_release,
 	.unlocked_ioctl = afu_ioctl,
+	.mmap = afu_mmap,
 };
 
+static int afu_dev_init(struct platform_device *pdev)
+{
+	struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev->dev);
+	struct dfl_afu *afu;
+
+	afu = devm_kzalloc(&pdev->dev, sizeof(*afu), GFP_KERNEL);
+	if (!afu)
+		return -ENOMEM;
+
+	afu->pdata = pdata;
+
+	mutex_lock(&pdata->lock);
+	dfl_fpga_pdata_set_private(pdata, afu);
+	afu_mmio_region_init(pdata);
+	mutex_unlock(&pdata->lock);
+
+	return 0;
+}
+
+static int afu_dev_destroy(struct platform_device *pdev)
+{
+	struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev->dev);
+	struct dfl_afu *afu;
+
+	mutex_lock(&pdata->lock);
+	afu = dfl_fpga_pdata_get_private(pdata);
+	afu_mmio_region_destroy(pdata);
+	dfl_fpga_pdata_set_private(pdata, NULL);
+	mutex_unlock(&pdata->lock);
+
+	return 0;
+}
+
 static int port_enable_set(struct platform_device *pdev, bool enable)
 {
 	struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev->dev);
@@ -312,14 +507,25 @@ static int afu_probe(struct platform_device *pdev)
 
 	dev_dbg(&pdev->dev, "%s\n", __func__);
 
+	ret = afu_dev_init(pdev);
+	if (ret)
+		goto exit;
+
 	ret = dfl_fpga_dev_feature_init(pdev, port_feature_drvs);
 	if (ret)
-		return ret;
+		goto dev_destroy;
 
 	ret = dfl_fpga_dev_ops_register(pdev, &afu_fops, THIS_MODULE);
-	if (ret)
+	if (ret) {
 		dfl_fpga_dev_feature_uinit(pdev);
+		goto dev_destroy;
+	}
+
+	return 0;
 
+dev_destroy:
+	afu_dev_destroy(pdev);
+exit:
 	return ret;
 }
 
@@ -329,6 +535,7 @@ static int afu_remove(struct platform_device *pdev)
 
 	dfl_fpga_dev_ops_unregister(pdev);
 	dfl_fpga_dev_feature_uinit(pdev);
+	afu_dev_destroy(pdev);
 
 	return 0;
 }
diff --git a/drivers/fpga/dfl-afu-region.c b/drivers/fpga/dfl-afu-region.c
new file mode 100644
index 0000000..0804b7a
--- /dev/null
+++ b/drivers/fpga/dfl-afu-region.c
@@ -0,0 +1,166 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for FPGA Accelerated Function Unit (AFU) MMIO Region Management
+ *
+ * Copyright (C) 2017-2018 Intel Corporation, Inc.
+ *
+ * Authors:
+ *   Wu Hao <hao.wu@intel.com>
+ *   Xiao Guangrong <guangrong.xiao@linux.intel.com>
+ */
+#include "dfl-afu.h"
+
+/**
+ * afu_mmio_region_init - init function for afu mmio region support
+ * @pdata: afu platform device's pdata.
+ */
+void afu_mmio_region_init(struct dfl_feature_platform_data *pdata)
+{
+	struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
+
+	INIT_LIST_HEAD(&afu->regions);
+}
+
+#define for_each_region(region, afu)	\
+	list_for_each_entry((region), &(afu)->regions, node)
+
+static struct dfl_afu_mmio_region *get_region_by_index(struct dfl_afu *afu,
+						       u32 region_index)
+{
+	struct dfl_afu_mmio_region *region;
+
+	for_each_region(region, afu)
+		if (region->index == region_index)
+			return region;
+
+	return NULL;
+}
+
+/**
+ * afu_mmio_region_add - add a mmio region to given feature dev.
+ *
+ * @region_index: region index.
+ * @region_size: region size.
+ * @phys: region's physical address of this region.
+ * @flags: region flags (access permission).
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int afu_mmio_region_add(struct dfl_feature_platform_data *pdata,
+			u32 region_index, u64 region_size, u64 phys, u32 flags)
+{
+	struct dfl_afu_mmio_region *region;
+	struct dfl_afu *afu;
+	int ret = 0;
+
+	region = devm_kzalloc(&pdata->dev->dev, sizeof(*region), GFP_KERNEL);
+	if (!region)
+		return -ENOMEM;
+
+	region->index = region_index;
+	region->size = region_size;
+	region->phys = phys;
+	region->flags = flags;
+
+	mutex_lock(&pdata->lock);
+
+	afu = dfl_fpga_pdata_get_private(pdata);
+
+	/* check if @index already exists */
+	if (get_region_by_index(afu, region_index)) {
+		mutex_unlock(&pdata->lock);
+		ret = -EEXIST;
+		goto exit;
+	}
+
+	region_size = PAGE_ALIGN(region_size);
+	region->offset = afu->region_cur_offset;
+	list_add(&region->node, &afu->regions);
+
+	afu->region_cur_offset += region_size;
+	afu->num_regions++;
+	mutex_unlock(&pdata->lock);
+
+	return 0;
+
+exit:
+	devm_kfree(&pdata->dev->dev, region);
+	return ret;
+}
+
+/**
+ * afu_mmio_region_destroy - destroy all mmio regions under given feature dev.
+ * @pdata: afu platform device's pdata.
+ */
+void afu_mmio_region_destroy(struct dfl_feature_platform_data *pdata)
+{
+	struct dfl_afu *afu = dfl_fpga_pdata_get_private(pdata);
+	struct dfl_afu_mmio_region *tmp, *region;
+
+	list_for_each_entry_safe(region, tmp, &afu->regions, node)
+		devm_kfree(&pdata->dev->dev, region);
+}
+
+/**
+ * afu_mmio_region_get_by_index - find an afu region by index.
+ * @pdata: afu platform device's pdata.
+ * @region_index: region index.
+ * @pregion: ptr to region for result.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int afu_mmio_region_get_by_index(struct dfl_feature_platform_data *pdata,
+				 u32 region_index,
+				 struct dfl_afu_mmio_region *pregion)
+{
+	struct dfl_afu_mmio_region *region;
+	struct dfl_afu *afu;
+	int ret = 0;
+
+	mutex_lock(&pdata->lock);
+	afu = dfl_fpga_pdata_get_private(pdata);
+	region = get_region_by_index(afu, region_index);
+	if (!region) {
+		ret = -EINVAL;
+		goto exit;
+	}
+	*pregion = *region;
+exit:
+	mutex_unlock(&pdata->lock);
+	return ret;
+}
+
+/**
+ * afu_mmio_region_get_by_offset - find an afu mmio region by offset and size
+ *
+ * @pdata: afu platform device's pdata.
+ * @offset: region offset from start of the device fd.
+ * @size: region size.
+ * @pregion: ptr to region for result.
+ *
+ * Find the region which fully contains the region described by input
+ * parameters (offset and size) from the feature dev's region linked list.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int afu_mmio_region_get_by_offset(struct dfl_feature_platform_data *pdata,
+				  u64 offset, u64 size,
+				  struct dfl_afu_mmio_region *pregion)
+{
+	struct dfl_afu_mmio_region *region;
+	struct dfl_afu *afu;
+	int ret = 0;
+
+	mutex_lock(&pdata->lock);
+	afu = dfl_fpga_pdata_get_private(pdata);
+	for_each_region(region, afu)
+		if (region->offset <= offset &&
+		    region->offset + region->size >= offset + size) {
+			*pregion = *region;
+			goto exit;
+		}
+	ret = -EINVAL;
+exit:
+	mutex_unlock(&pdata->lock);
+	return ret;
+}
diff --git a/drivers/fpga/dfl-afu.h b/drivers/fpga/dfl-afu.h
new file mode 100644
index 0000000..11ce2cf
--- /dev/null
+++ b/drivers/fpga/dfl-afu.h
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Header file for FPGA Accelerated Function Unit (AFU) Driver
+ *
+ * Copyright (C) 2017-2018 Intel Corporation, Inc.
+ *
+ * Authors:
+ *     Wu Hao <hao.wu@intel.com>
+ *     Xiao Guangrong <guangrong.xiao@linux.intel.com>
+ *     Joseph Grecco <joe.grecco@intel.com>
+ *     Enno Luebbers <enno.luebbers@intel.com>
+ *     Tim Whisonant <tim.whisonant@intel.com>
+ *     Ananda Ravuri <ananda.ravuri@intel.com>
+ *     Henry Mitchel <henry.mitchel@intel.com>
+ */
+
+#ifndef __DFL_AFU_H
+#define __DFL_AFU_H
+
+#include <linux/mm.h>
+
+#include "dfl.h"
+
+/**
+ * struct dfl_afu_mmio_region - afu mmio region data structure
+ *
+ * @index: region index.
+ * @flags: region flags (access permission).
+ * @size: region size.
+ * @offset: region offset from start of the device fd.
+ * @phys: region's physical address.
+ * @node: node to add to afu feature dev's region list.
+ */
+struct dfl_afu_mmio_region {
+	u32 index;
+	u32 flags;
+	u64 size;
+	u64 offset;
+	u64 phys;
+	struct list_head node;
+};
+
+/**
+ * struct dfl_afu - afu device data structure
+ *
+ * @region_cur_offset: current region offset from start to the device fd.
+ * @num_regions: num of mmio regions.
+ * @regions: the mmio region linked list of this afu feature device.
+ * @num_umsgs: num of umsgs.
+ * @pdata: afu platform device's pdata.
+ */
+struct dfl_afu {
+	u64 region_cur_offset;
+	int num_regions;
+	u8 num_umsgs;
+	struct list_head regions;
+
+	struct dfl_feature_platform_data *pdata;
+};
+
+void afu_mmio_region_init(struct dfl_feature_platform_data *pdata);
+int afu_mmio_region_add(struct dfl_feature_platform_data *pdata,
+			u32 region_index, u64 region_size, u64 phys, u32 flags);
+void afu_mmio_region_destroy(struct dfl_feature_platform_data *pdata);
+int afu_mmio_region_get_by_index(struct dfl_feature_platform_data *pdata,
+				 u32 region_index,
+				 struct dfl_afu_mmio_region *pregion);
+int afu_mmio_region_get_by_offset(struct dfl_feature_platform_data *pdata,
+				  u64 offset, u64 size,
+				  struct dfl_afu_mmio_region *pregion);
+#endif
diff --git a/include/uapi/linux/fpga-dfl.h b/include/uapi/linux/fpga-dfl.h
index e6b4dd2..a3ccdfb 100644
--- a/include/uapi/linux/fpga-dfl.h
+++ b/include/uapi/linux/fpga-dfl.h
@@ -66,6 +66,54 @@
 
 #define DFL_FPGA_PORT_RESET		_IO(DFL_FPGA_MAGIC, DFL_PORT_BASE + 0)
 
+/**
+ * DFL_FPGA_PORT_GET_INFO - _IOR(DFL_FPGA_MAGIC, DFL_PORT_BASE + 1,
+ *						struct dfl_fpga_port_info)
+ *
+ * Retrieve information about the fpga port.
+ * Driver fills the info in provided struct dfl_fpga_port_info.
+ * Return: 0 on success, -errno on failure.
+ */
+struct dfl_fpga_port_info {
+	/* Input */
+	__u32 argsz;		/* Structure length */
+	/* Output */
+	__u32 flags;		/* Zero for now */
+	__u32 num_regions;	/* The number of supported regions */
+	__u32 num_umsgs;	/* The number of allocated umsgs */
+};
+
+#define DFL_FPGA_PORT_GET_INFO		_IO(DFL_FPGA_MAGIC, DFL_PORT_BASE + 1)
+
+/**
+ * FPGA_PORT_GET_REGION_INFO - _IOWR(FPGA_MAGIC, PORT_BASE + 2,
+ *					struct dfl_fpga_port_region_info)
+ *
+ * Retrieve information about a device memory region.
+ * Caller provides struct dfl_fpga_port_region_info with index value set.
+ * Driver returns the region info in other fields.
+ * Return: 0 on success, -errno on failure.
+ */
+struct dfl_fpga_port_region_info {
+	/* input */
+	__u32 argsz;		/* Structure length */
+	/* Output */
+	__u32 flags;		/* Access permission */
+#define DFL_PORT_REGION_READ	(1 << 0)	/* Region is readable */
+#define DFL_PORT_REGION_WRITE	(1 << 1)	/* Region is writable */
+#define DFL_PORT_REGION_MMAP	(1 << 2)	/* Can be mmaped to userspace */
+	/* Input */
+	__u32 index;		/* Region index */
+#define DFL_PORT_REGION_INDEX_AFU	0	/* AFU */
+#define DFL_PORT_REGION_INDEX_STP	1	/* Signal Tap */
+	__u32 padding;
+	/* Output */
+	__u64 size;		/* Region size (bytes) */
+	__u64 offset;		/* Region offset from start of device fd */
+};
+
+#define DFL_FPGA_PORT_GET_REGION_INFO	_IO(DFL_FPGA_MAGIC, DFL_PORT_BASE + 2)
+
 /* IOCTLs for FME file descriptor */
 
 /**
-- 
1.8.3.1