drivers/fpga/of-fpga-region.c - linux/kernel/git/gregkh/usb - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * FPGA Region - Device Tree support for FPGA programming under Linux
  *
  *  Copyright (C) 2013-2016 Altera Corporation
  *  Copyright (C) 2017 Intel Corporation
  */
 #include <linux/fpga/fpga-bridge.h>
 #include <linux/fpga/fpga-mgr.h>
 #include <linux/fpga/fpga-region.h>
 #include <linux/idr.h>
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/of_platform.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>

 static const struct of_device_id fpga_region_of_match[] = {
 	{ .compatible = "fpga-region", },
 	{},
 };
 MODULE_DEVICE_TABLE(of, fpga_region_of_match);

 /**
  * of_fpga_region_find - find FPGA region
  * @np: device node of FPGA Region
  *
  * Caller will need to put_device(&region->dev) when done.
  *
  * Returns FPGA Region struct or NULL
  */
 static struct fpga_region *of_fpga_region_find(struct device_node *np)
 {
 	return fpga_region_class_find(NULL, np, device_match_of_node);
 }

 /**
  * of_fpga_region_get_mgr - get reference for FPGA manager
  * @np: device node of FPGA region
  *
  * Get FPGA Manager from "fpga-mgr" property or from ancestor region.
  *
  * Caller should call fpga_mgr_put() when done with manager.
  *
  * Return: fpga manager struct or IS_ERR() condition containing error code.
  */
 static struct fpga_manager *of_fpga_region_get_mgr(struct device_node *np)
 {
 	struct device_node  *mgr_node;
 	struct fpga_manager *mgr;

 	of_node_get(np);
 	while (np) {
 		if (of_device_is_compatible(np, "fpga-region")) {
 			mgr_node = of_parse_phandle(np, "fpga-mgr", 0);
 			if (mgr_node) {
 				mgr = of_fpga_mgr_get(mgr_node);
 				of_node_put(mgr_node);
 				of_node_put(np);
 				return mgr;
 			}
 		}
 		np = of_get_next_parent(np);
 	}
 	of_node_put(np);

 	return ERR_PTR(-EINVAL);
 }

 /**
  * of_fpga_region_get_bridges - create a list of bridges
  * @region: FPGA region
  *
  * Create a list of bridges including the parent bridge and the bridges
  * specified by "fpga-bridges" property.  Note that the
  * fpga_bridges_enable/disable/put functions are all fine with an empty list
  * if that happens.
  *
  * Caller should call fpga_bridges_put(&region->bridge_list) when
  * done with the bridges.
  *
  * Return 0 for success (even if there are no bridges specified)
  * or -EBUSY if any of the bridges are in use.
  */
 static int of_fpga_region_get_bridges(struct fpga_region *region)
 {
 	struct device *dev = &region->dev;
 	struct device_node *region_np = dev->of_node;
 	struct fpga_image_info *info = region->info;
 	struct device_node *br, *np, *parent_br = NULL;
 	int i, ret;

 	/* If parent is a bridge, add to list */
 	ret = of_fpga_bridge_get_to_list(region_np->parent, info,
 					 &region->bridge_list);

 	/* -EBUSY means parent is a bridge that is under use. Give up. */
 	if (ret == -EBUSY)
 		return ret;

 	/* Zero return code means parent was a bridge and was added to list. */
 	if (!ret)
 		parent_br = region_np->parent;

 	/* If overlay has a list of bridges, use it. */
 	br = of_parse_phandle(info->overlay, "fpga-bridges", 0);
 	if (br) {
 		of_node_put(br);
 		np = info->overlay;
 	} else {
 		np = region_np;
 	}

 	for (i = 0; ; i++) {
 		br = of_parse_phandle(np, "fpga-bridges", i);
 		if (!br)
 			break;

 		/* If parent bridge is in list, skip it. */
 		if (br == parent_br) {
 			of_node_put(br);
 			continue;
 		}

 		/* If node is a bridge, get it and add to list */
 		ret = of_fpga_bridge_get_to_list(br, info,
 						 &region->bridge_list);
 		of_node_put(br);

 		/* If any of the bridges are in use, give up */
 		if (ret == -EBUSY) {
 			fpga_bridges_put(&region->bridge_list);
 			return -EBUSY;
 		}
 	}

 	return 0;
 }

 /**
  * child_regions_with_firmware
  * @overlay: device node of the overlay
  *
  * If the overlay adds child FPGA regions, they are not allowed to have
  * firmware-name property.
  *
  * Return 0 for OK or -EINVAL if child FPGA region adds firmware-name.
  */
 static int child_regions_with_firmware(struct device_node *overlay)
 {
 	struct device_node *child_region;
 	const char *child_firmware_name;
 	int ret = 0;

 	of_node_get(overlay);

 	child_region = of_find_matching_node(overlay, fpga_region_of_match);
 	while (child_region) {
 		if (!of_property_read_string(child_region, "firmware-name",
 					     &child_firmware_name)) {
 			ret = -EINVAL;
 			break;
 		}
 		child_region = of_find_matching_node(child_region,
 						     fpga_region_of_match);
 	}

 	of_node_put(child_region);

 	if (ret)
 		pr_err("firmware-name not allowed in child FPGA region: %pOF",
 		       child_region);

 	return ret;
 }

 /**
  * of_fpga_region_parse_ov - parse and check overlay applied to region
  *
  * @region: FPGA region
  * @overlay: overlay applied to the FPGA region
  *
  * Given an overlay applied to a FPGA region, parse the FPGA image specific
  * info in the overlay and do some checking.
  *
  * Returns:
  *   NULL if overlay doesn't direct us to program the FPGA.
  *   fpga_image_info struct if there is an image to program.
  *   error code for invalid overlay.
  */
 static struct fpga_image_info *of_fpga_region_parse_ov(
 						struct fpga_region *region,
 						struct device_node *overlay)
 {
 	struct device *dev = &region->dev;
 	struct fpga_image_info *info;
 	const char *firmware_name;
 	int ret;

 	if (region->info) {
 		dev_err(dev, "Region already has overlay applied.\n");
 		return ERR_PTR(-EINVAL);
 	}

 	/*
 	 * Reject overlay if child FPGA Regions added in the overlay have
 	 * firmware-name property (would mean that an FPGA region that has
 	 * not been added to the live tree yet is doing FPGA programming).
 	 */
 	ret = child_regions_with_firmware(overlay);
 	if (ret)
 		return ERR_PTR(ret);

 	info = fpga_image_info_alloc(dev);
 	if (!info)
 		return ERR_PTR(-ENOMEM);

 	info->overlay = overlay;

 	/* Read FPGA region properties from the overlay */
 	if (of_property_read_bool(overlay, "partial-fpga-config"))
 		info->flags |= FPGA_MGR_PARTIAL_RECONFIG;

 	if (of_property_read_bool(overlay, "external-fpga-config"))
 		info->flags |= FPGA_MGR_EXTERNAL_CONFIG;

 	if (of_property_read_bool(overlay, "encrypted-fpga-config"))
 		info->flags |= FPGA_MGR_ENCRYPTED_BITSTREAM;

 	if (!of_property_read_string(overlay, "firmware-name",
 				     &firmware_name)) {
 		info->firmware_name = devm_kstrdup(dev, firmware_name,
 						   GFP_KERNEL);
 		if (!info->firmware_name)
 			return ERR_PTR(-ENOMEM);
 	}

 	of_property_read_u32(overlay, "region-unfreeze-timeout-us",
 			     &info->enable_timeout_us);

 	of_property_read_u32(overlay, "region-freeze-timeout-us",
 			     &info->disable_timeout_us);

 	of_property_read_u32(overlay, "config-complete-timeout-us",
 			     &info->config_complete_timeout_us);

 	/* If overlay is not programming the FPGA, don't need FPGA image info */
 	if (!info->firmware_name) {
 		ret = 0;
 		goto ret_no_info;
 	}

 	/*
 	 * If overlay informs us FPGA was externally programmed, specifying
 	 * firmware here would be ambiguous.
 	 */
 	if (info->flags & FPGA_MGR_EXTERNAL_CONFIG) {
 		dev_err(dev, "error: specified firmware and external-fpga-config");
 		ret = -EINVAL;
 		goto ret_no_info;
 	}

 	return info;
 ret_no_info:
 	fpga_image_info_free(info);
 	return ERR_PTR(ret);
 }

 /**
  * of_fpga_region_notify_pre_apply - pre-apply overlay notification
  *
  * @region: FPGA region that the overlay was applied to
  * @nd: overlay notification data
  *
  * Called when an overlay targeted to a FPGA Region is about to be applied.
  * Parses the overlay for properties that influence how the FPGA will be
  * programmed and does some checking. If the checks pass, programs the FPGA.
  * If the checks fail, overlay is rejected and does not get added to the
  * live tree.
  *
  * Returns 0 for success or negative error code for failure.
  */
 static int of_fpga_region_notify_pre_apply(struct fpga_region *region,
 					   struct of_overlay_notify_data *nd)
 {
 	struct device *dev = &region->dev;
 	struct fpga_image_info *info;
 	int ret;

 	info = of_fpga_region_parse_ov(region, nd->overlay);
 	if (IS_ERR(info))
 		return PTR_ERR(info);

 	/* If overlay doesn't program the FPGA, accept it anyway. */
 	if (!info)
 		return 0;

 	if (region->info) {
 		dev_err(dev, "Region already has overlay applied.\n");
 		return -EINVAL;
 	}

 	region->info = info;
 	ret = fpga_region_program_fpga(region);
 	if (ret) {
 		/* error; reject overlay */
 		fpga_image_info_free(info);
 		region->info = NULL;
 	}

 	return ret;
 }

 /**
  * of_fpga_region_notify_post_remove - post-remove overlay notification
  *
  * @region: FPGA region that was targeted by the overlay that was removed
  * @nd: overlay notification data
  *
  * Called after an overlay has been removed if the overlay's target was a
  * FPGA region.
  */
 static void of_fpga_region_notify_post_remove(struct fpga_region *region,
 					      struct of_overlay_notify_data *nd)
 {
 	fpga_bridges_disable(&region->bridge_list);
 	fpga_bridges_put(&region->bridge_list);
 	fpga_image_info_free(region->info);
 	region->info = NULL;
 }

 /**
  * of_fpga_region_notify - reconfig notifier for dynamic DT changes
  * @nb:		notifier block
  * @action:	notifier action
  * @arg:	reconfig data
  *
  * This notifier handles programming a FPGA when a "firmware-name" property is
  * added to a fpga-region.
  *
  * Returns NOTIFY_OK or error if FPGA programming fails.
  */
 static int of_fpga_region_notify(struct notifier_block *nb,
 				 unsigned long action, void *arg)
 {
 	struct of_overlay_notify_data *nd = arg;
 	struct fpga_region *region;
 	int ret;

 	switch (action) {
 	case OF_OVERLAY_PRE_APPLY:
 		pr_debug("%s OF_OVERLAY_PRE_APPLY\n", __func__);
 		break;
 	case OF_OVERLAY_POST_APPLY:
 		pr_debug("%s OF_OVERLAY_POST_APPLY\n", __func__);
 		return NOTIFY_OK;       /* not for us */
 	case OF_OVERLAY_PRE_REMOVE:
 		pr_debug("%s OF_OVERLAY_PRE_REMOVE\n", __func__);
 		return NOTIFY_OK;       /* not for us */
 	case OF_OVERLAY_POST_REMOVE:
 		pr_debug("%s OF_OVERLAY_POST_REMOVE\n", __func__);
 		break;
 	default:			/* should not happen */
 		return NOTIFY_OK;
 	}

 	region = of_fpga_region_find(nd->target);
 	if (!region)
 		return NOTIFY_OK;

 	ret = 0;
 	switch (action) {
 	case OF_OVERLAY_PRE_APPLY:
 		ret = of_fpga_region_notify_pre_apply(region, nd);
 		break;

 	case OF_OVERLAY_POST_REMOVE:
 		of_fpga_region_notify_post_remove(region, nd);
 		break;
 	}

 	put_device(&region->dev);

 	if (ret)
 		return notifier_from_errno(ret);

 	return NOTIFY_OK;
 }

 static struct notifier_block fpga_region_of_nb = {
 	.notifier_call = of_fpga_region_notify,
 };

 static int of_fpga_region_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct device_node *np = dev->of_node;
 	struct fpga_region *region;
 	struct fpga_manager *mgr;
 	int ret;

 	/* Find the FPGA mgr specified by region or parent region. */
 	mgr = of_fpga_region_get_mgr(np);
 	if (IS_ERR(mgr))
 		return -EPROBE_DEFER;

 	region = devm_fpga_region_create(dev, mgr, of_fpga_region_get_bridges);
 	if (!region) {
 		ret = -ENOMEM;
 		goto eprobe_mgr_put;
 	}

 	ret = fpga_region_register(region);
 	if (ret)
 		goto eprobe_mgr_put;

 	of_platform_populate(np, fpga_region_of_match, NULL, &region->dev);
 	platform_set_drvdata(pdev, region);

 	dev_info(dev, "FPGA Region probed\n");

 	return 0;

 eprobe_mgr_put:
 	fpga_mgr_put(mgr);
 	return ret;
 }

 static int of_fpga_region_remove(struct platform_device *pdev)
 {
 	struct fpga_region *region = platform_get_drvdata(pdev);
 	struct fpga_manager *mgr = region->mgr;

 	fpga_region_unregister(region);
 	fpga_mgr_put(mgr);

 	return 0;
 }

 static struct platform_driver of_fpga_region_driver = {
 	.probe = of_fpga_region_probe,
 	.remove = of_fpga_region_remove,
 	.driver = {
 		.name	= "of-fpga-region",
 		.of_match_table = of_match_ptr(fpga_region_of_match),
 	},
 };

 /**
  * fpga_region_init - init function for fpga_region class
  * Creates the fpga_region class and registers a reconfig notifier.
  */
 static int __init of_fpga_region_init(void)
 {
 	int ret;

 	ret = of_overlay_notifier_register(&fpga_region_of_nb);
 	if (ret)
 		return ret;

 	ret = platform_driver_register(&of_fpga_region_driver);
 	if (ret)
 		goto err_plat;

 	return 0;

 err_plat:
 	of_overlay_notifier_unregister(&fpga_region_of_nb);
 	return ret;
 }

 static void __exit of_fpga_region_exit(void)
 {
 	platform_driver_unregister(&of_fpga_region_driver);
 	of_overlay_notifier_unregister(&fpga_region_of_nb);
 }

 subsys_initcall(of_fpga_region_init);
 module_exit(of_fpga_region_exit);

 MODULE_DESCRIPTION("FPGA Region");
 MODULE_AUTHOR("Alan Tull <atull@kernel.org>");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* FPGA Region - Device Tree support for FPGA programming under Linux
	*
	* Copyright (C) 2013-2016 Altera Corporation
	* Copyright (C) 2017 Intel Corporation
	*/
	#include <linux/fpga/fpga-bridge.h>
	#include <linux/fpga/fpga-mgr.h>
	#include <linux/fpga/fpga-region.h>
	#include <linux/idr.h>
	#include <linux/kernel.h>
	#include <linux/list.h>
	#include <linux/module.h>
	#include <linux/of_platform.h>
	#include <linux/slab.h>
	#include <linux/spinlock.h>

	static const struct of_device_id fpga_region_of_match[] = {
	{ .compatible = "fpga-region", },
	{},
	};
	MODULE_DEVICE_TABLE(of, fpga_region_of_match);

	/**
	* of_fpga_region_find - find FPGA region
	* @np: device node of FPGA Region
	*
	* Caller will need to put_device(&region->dev) when done.
	*
	* Returns FPGA Region struct or NULL
	*/
	static struct fpga_region of_fpga_region_find(struct device_node np)
	{
	return fpga_region_class_find(NULL, np, device_match_of_node);
	}

	/**
	* of_fpga_region_get_mgr - get reference for FPGA manager
	* @np: device node of FPGA region
	*
	* Get FPGA Manager from "fpga-mgr" property or from ancestor region.
	*
	* Caller should call fpga_mgr_put() when done with manager.
	*
	* Return: fpga manager struct or IS_ERR() condition containing error code.
	*/
	static struct fpga_manager of_fpga_region_get_mgr(struct device_node np)
	{
	struct device_node *mgr_node;
	struct fpga_manager *mgr;

	of_node_get(np);
	while (np) {
	if (of_device_is_compatible(np, "fpga-region")) {
	mgr_node = of_parse_phandle(np, "fpga-mgr", 0);
	if (mgr_node) {
	mgr = of_fpga_mgr_get(mgr_node);
	of_node_put(mgr_node);
	of_node_put(np);
	return mgr;
	}
	}
	np = of_get_next_parent(np);
	}
	of_node_put(np);

	return ERR_PTR(-EINVAL);
	}

	/**
	* of_fpga_region_get_bridges - create a list of bridges
	* @region: FPGA region
	*
	* Create a list of bridges including the parent bridge and the bridges
	* specified by "fpga-bridges" property. Note that the
	* fpga_bridges_enable/disable/put functions are all fine with an empty list
	* if that happens.
	*
	* Caller should call fpga_bridges_put(&region->bridge_list) when
	* done with the bridges.
	*
	* Return 0 for success (even if there are no bridges specified)
	* or -EBUSY if any of the bridges are in use.
	*/
	static int of_fpga_region_get_bridges(struct fpga_region *region)
	{
	struct device *dev = &region->dev;
	struct device_node *region_np = dev->of_node;
	struct fpga_image_info *info = region->info;
	struct device_node br, np, *parent_br = NULL;
	int i, ret;

	/* If parent is a bridge, add to list */
	ret = of_fpga_bridge_get_to_list(region_np->parent, info,
	&region->bridge_list);

	/* -EBUSY means parent is a bridge that is under use. Give up. */
	if (ret == -EBUSY)
	return ret;

	/* Zero return code means parent was a bridge and was added to list. */
	if (!ret)
	parent_br = region_np->parent;

	/* If overlay has a list of bridges, use it. */
	br = of_parse_phandle(info->overlay, "fpga-bridges", 0);
	if (br) {
	of_node_put(br);
	np = info->overlay;
	} else {
	np = region_np;
	}

	for (i = 0; ; i++) {
	br = of_parse_phandle(np, "fpga-bridges", i);
	if (!br)
	break;

	/* If parent bridge is in list, skip it. */
	if (br == parent_br) {
	of_node_put(br);
	continue;
	}

	/* If node is a bridge, get it and add to list */
	ret = of_fpga_bridge_get_to_list(br, info,
	&region->bridge_list);
	of_node_put(br);

	/* If any of the bridges are in use, give up */
	if (ret == -EBUSY) {
	fpga_bridges_put(&region->bridge_list);
	return -EBUSY;
	}
	}

	return 0;
	}

	/**
	* child_regions_with_firmware
	* @overlay: device node of the overlay
	*
	* If the overlay adds child FPGA regions, they are not allowed to have
	* firmware-name property.
	*
	* Return 0 for OK or -EINVAL if child FPGA region adds firmware-name.
	*/
	static int child_regions_with_firmware(struct device_node *overlay)
	{
	struct device_node *child_region;
	const char *child_firmware_name;
	int ret = 0;

	of_node_get(overlay);

	child_region = of_find_matching_node(overlay, fpga_region_of_match);
	while (child_region) {
	if (!of_property_read_string(child_region, "firmware-name",
	&child_firmware_name)) {
	ret = -EINVAL;
	break;
	}
	child_region = of_find_matching_node(child_region,
	fpga_region_of_match);
	}

	of_node_put(child_region);

	if (ret)
	pr_err("firmware-name not allowed in child FPGA region: %pOF",
	child_region);

	return ret;
	}

	/**
	* of_fpga_region_parse_ov - parse and check overlay applied to region
	*
	* @region: FPGA region
	* @overlay: overlay applied to the FPGA region
	*
	* Given an overlay applied to a FPGA region, parse the FPGA image specific
	* info in the overlay and do some checking.
	*
	* Returns:
	* NULL if overlay doesn't direct us to program the FPGA.
	* fpga_image_info struct if there is an image to program.
	* error code for invalid overlay.
	*/
	static struct fpga_image_info *of_fpga_region_parse_ov(
	struct fpga_region *region,
	struct device_node *overlay)
	{
	struct device *dev = &region->dev;
	struct fpga_image_info *info;
	const char *firmware_name;
	int ret;

	if (region->info) {
	dev_err(dev, "Region already has overlay applied.\n");
	return ERR_PTR(-EINVAL);
	}

	/*
	* Reject overlay if child FPGA Regions added in the overlay have
	* firmware-name property (would mean that an FPGA region that has
	* not been added to the live tree yet is doing FPGA programming).
	*/
	ret = child_regions_with_firmware(overlay);
	if (ret)
	return ERR_PTR(ret);

	info = fpga_image_info_alloc(dev);
	if (!info)
	return ERR_PTR(-ENOMEM);

	info->overlay = overlay;

	/* Read FPGA region properties from the overlay */
	if (of_property_read_bool(overlay, "partial-fpga-config"))
	info->flags \|= FPGA_MGR_PARTIAL_RECONFIG;

	if (of_property_read_bool(overlay, "external-fpga-config"))
	info->flags \|= FPGA_MGR_EXTERNAL_CONFIG;

	if (of_property_read_bool(overlay, "encrypted-fpga-config"))
	info->flags \|= FPGA_MGR_ENCRYPTED_BITSTREAM;

	if (!of_property_read_string(overlay, "firmware-name",
	&firmware_name)) {
	info->firmware_name = devm_kstrdup(dev, firmware_name,
	GFP_KERNEL);
	if (!info->firmware_name)
	return ERR_PTR(-ENOMEM);
	}

	of_property_read_u32(overlay, "region-unfreeze-timeout-us",
	&info->enable_timeout_us);

	of_property_read_u32(overlay, "region-freeze-timeout-us",
	&info->disable_timeout_us);

	of_property_read_u32(overlay, "config-complete-timeout-us",
	&info->config_complete_timeout_us);

	/* If overlay is not programming the FPGA, don't need FPGA image info */
	if (!info->firmware_name) {
	ret = 0;
	goto ret_no_info;
	}

	/*
	* If overlay informs us FPGA was externally programmed, specifying
	* firmware here would be ambiguous.
	*/
	if (info->flags & FPGA_MGR_EXTERNAL_CONFIG) {
	dev_err(dev, "error: specified firmware and external-fpga-config");
	ret = -EINVAL;
	goto ret_no_info;
	}

	return info;
	ret_no_info:
	fpga_image_info_free(info);
	return ERR_PTR(ret);
	}

	/**
	* of_fpga_region_notify_pre_apply - pre-apply overlay notification
	*
	* @region: FPGA region that the overlay was applied to
	* @nd: overlay notification data
	*
	* Called when an overlay targeted to a FPGA Region is about to be applied.
	* Parses the overlay for properties that influence how the FPGA will be
	* programmed and does some checking. If the checks pass, programs the FPGA.
	* If the checks fail, overlay is rejected and does not get added to the
	* live tree.
	*
	* Returns 0 for success or negative error code for failure.
	*/
	static int of_fpga_region_notify_pre_apply(struct fpga_region *region,
	struct of_overlay_notify_data *nd)
	{
	struct device *dev = &region->dev;
	struct fpga_image_info *info;
	int ret;

	info = of_fpga_region_parse_ov(region, nd->overlay);
	if (IS_ERR(info))
	return PTR_ERR(info);

	/* If overlay doesn't program the FPGA, accept it anyway. */
	if (!info)
	return 0;

	if (region->info) {
	dev_err(dev, "Region already has overlay applied.\n");
	return -EINVAL;
	}

	region->info = info;
	ret = fpga_region_program_fpga(region);
	if (ret) {
	/* error; reject overlay */
	fpga_image_info_free(info);
	region->info = NULL;
	}

	return ret;
	}

	/**
	* of_fpga_region_notify_post_remove - post-remove overlay notification
	*
	* @region: FPGA region that was targeted by the overlay that was removed
	* @nd: overlay notification data
	*
	* Called after an overlay has been removed if the overlay's target was a
	* FPGA region.
	*/
	static void of_fpga_region_notify_post_remove(struct fpga_region *region,
	struct of_overlay_notify_data *nd)
	{
	fpga_bridges_disable(&region->bridge_list);
	fpga_bridges_put(&region->bridge_list);
	fpga_image_info_free(region->info);
	region->info = NULL;
	}

	/**
	* of_fpga_region_notify - reconfig notifier for dynamic DT changes
	* @nb: notifier block
	* @action: notifier action
	* @arg: reconfig data
	*
	* This notifier handles programming a FPGA when a "firmware-name" property is
	* added to a fpga-region.
	*
	* Returns NOTIFY_OK or error if FPGA programming fails.
	*/
	static int of_fpga_region_notify(struct notifier_block *nb,
	unsigned long action, void *arg)
	{
	struct of_overlay_notify_data *nd = arg;
	struct fpga_region *region;
	int ret;

	switch (action) {
	case OF_OVERLAY_PRE_APPLY:
	pr_debug("%s OF_OVERLAY_PRE_APPLY\n", __func__);
	break;
	case OF_OVERLAY_POST_APPLY:
	pr_debug("%s OF_OVERLAY_POST_APPLY\n", __func__);
	return NOTIFY_OK; /* not for us */
	case OF_OVERLAY_PRE_REMOVE:
	pr_debug("%s OF_OVERLAY_PRE_REMOVE\n", __func__);
	return NOTIFY_OK; /* not for us */
	case OF_OVERLAY_POST_REMOVE:
	pr_debug("%s OF_OVERLAY_POST_REMOVE\n", __func__);
	break;
	default: /* should not happen */
	return NOTIFY_OK;
	}

	region = of_fpga_region_find(nd->target);
	if (!region)
	return NOTIFY_OK;

	ret = 0;
	switch (action) {
	case OF_OVERLAY_PRE_APPLY:
	ret = of_fpga_region_notify_pre_apply(region, nd);
	break;

	case OF_OVERLAY_POST_REMOVE:
	of_fpga_region_notify_post_remove(region, nd);
	break;
	}

	put_device(&region->dev);

	if (ret)
	return notifier_from_errno(ret);

	return NOTIFY_OK;
	}

	static struct notifier_block fpga_region_of_nb = {
	.notifier_call = of_fpga_region_notify,
	};

	static int of_fpga_region_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct device_node *np = dev->of_node;
	struct fpga_region *region;
	struct fpga_manager *mgr;
	int ret;

	/* Find the FPGA mgr specified by region or parent region. */
	mgr = of_fpga_region_get_mgr(np);
	if (IS_ERR(mgr))
	return -EPROBE_DEFER;

	region = devm_fpga_region_create(dev, mgr, of_fpga_region_get_bridges);
	if (!region) {
	ret = -ENOMEM;
	goto eprobe_mgr_put;
	}

	ret = fpga_region_register(region);
	if (ret)
	goto eprobe_mgr_put;

	of_platform_populate(np, fpga_region_of_match, NULL, &region->dev);
	platform_set_drvdata(pdev, region);

	dev_info(dev, "FPGA Region probed\n");

	return 0;

	eprobe_mgr_put:
	fpga_mgr_put(mgr);
	return ret;
	}

	static int of_fpga_region_remove(struct platform_device *pdev)
	{
	struct fpga_region *region = platform_get_drvdata(pdev);
	struct fpga_manager *mgr = region->mgr;

	fpga_region_unregister(region);
	fpga_mgr_put(mgr);

	return 0;
	}

	static struct platform_driver of_fpga_region_driver = {
	.probe = of_fpga_region_probe,
	.remove = of_fpga_region_remove,
	.driver = {
	.name = "of-fpga-region",
	.of_match_table = of_match_ptr(fpga_region_of_match),
	},
	};

	/**
	* fpga_region_init - init function for fpga_region class
	* Creates the fpga_region class and registers a reconfig notifier.
	*/
	static int __init of_fpga_region_init(void)
	{
	int ret;

	ret = of_overlay_notifier_register(&fpga_region_of_nb);
	if (ret)
	return ret;

	ret = platform_driver_register(&of_fpga_region_driver);
	if (ret)
	goto err_plat;

	return 0;

	err_plat:
	of_overlay_notifier_unregister(&fpga_region_of_nb);
	return ret;
	}

	static void __exit of_fpga_region_exit(void)
	{
	platform_driver_unregister(&of_fpga_region_driver);
	of_overlay_notifier_unregister(&fpga_region_of_nb);
	}

	subsys_initcall(of_fpga_region_init);
	module_exit(of_fpga_region_exit);

	MODULE_DESCRIPTION("FPGA Region");
	MODULE_AUTHOR("Alan Tull <atull@kernel.org>");
	MODULE_LICENSE("GPL v2");