drivers/fpga/fpga-region.c - arm/linux - Git at Google

 /*
  * FPGA Region - Device Tree support for FPGA programming under Linux
  *
  *  Copyright (C) 2013-2016 Altera Corporation
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
  * version 2, as published by the Free Software Foundation.
  *
  * This program is distributed in the hope it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  * more details.
  *
  * You should have received a copy of the GNU General Public License along with
  * this program.  If not, see <http://www.gnu.org/licenses/>.
  */

 #include <linux/fpga/fpga-bridge.h>
 #include <linux/fpga/fpga-mgr.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>

 /**
  * struct fpga_region - FPGA Region structure
  * @dev: FPGA Region device
  * @mutex: enforces exclusive reference to region
  * @bridge_list: list of FPGA bridges specified in region
  * @info: fpga image specific information
  */
 struct fpga_region {
 	struct device dev;
 	struct mutex mutex; /* for exclusive reference to region */
 	struct list_head bridge_list;
 	struct fpga_image_info *info;
 };

 #define to_fpga_region(d) container_of(d, struct fpga_region, dev)

 static DEFINE_IDA(fpga_region_ida);
 static struct class *fpga_region_class;

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

 static int fpga_region_of_node_match(struct device *dev, const void *data)
 {
 	return dev->of_node == data;
 }

 /**
  * 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 *fpga_region_find(struct device_node *np)
 {
 	struct device *dev;

 	dev = class_find_device(fpga_region_class, NULL, np,
 				fpga_region_of_node_match);
 	if (!dev)
 		return NULL;

 	return to_fpga_region(dev);
 }

 /**
  * fpga_region_get - get an exclusive reference to a fpga region
  * @region: FPGA Region struct
  *
  * Caller should call fpga_region_put() when done with region.
  *
  * Return fpga_region struct if successful.
  * Return -EBUSY if someone already has a reference to the region.
  * Return -ENODEV if @np is not a FPGA Region.
  */
 static struct fpga_region *fpga_region_get(struct fpga_region *region)
 {
 	struct device *dev = &region->dev;

 	if (!mutex_trylock(&region->mutex)) {
 		dev_dbg(dev, "%s: FPGA Region already in use\n", __func__);
 		return ERR_PTR(-EBUSY);
 	}

 	get_device(dev);
 	of_node_get(dev->of_node);
 	if (!try_module_get(dev->parent->driver->owner)) {
 		of_node_put(dev->of_node);
 		put_device(dev);
 		mutex_unlock(&region->mutex);
 		return ERR_PTR(-ENODEV);
 	}

 	dev_dbg(&region->dev, "get\n");

 	return region;
 }

 /**
  * fpga_region_put - release a reference to a region
  *
  * @region: FPGA region
  */
 static void fpga_region_put(struct fpga_region *region)
 {
 	struct device *dev = &region->dev;

 	dev_dbg(&region->dev, "put\n");

 	module_put(dev->parent->driver->owner);
 	of_node_put(dev->of_node);
 	put_device(dev);
 	mutex_unlock(&region->mutex);
 }

 /**
  * fpga_region_get_manager - get exclusive reference for FPGA manager
  * @region: 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 *fpga_region_get_manager(struct fpga_region *region)
 {
 	struct device *dev = &region->dev;
 	struct device_node *np = dev->of_node;
 	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(np);
 				return mgr;
 			}
 		}
 		np = of_get_next_parent(np);
 	}
 	of_node_put(np);

 	return ERR_PTR(-EINVAL);
 }

 /**
  * fpga_region_get_bridges - create a list of bridges
  * @region: FPGA region
  * @overlay: device node of the overlay
  *
  * 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 fpga_region_get_bridges(struct fpga_region *region,
 				   struct device_node *overlay)
 {
 	struct device *dev = &region->dev;
 	struct device_node *region_np = dev->of_node;
 	struct device_node *br, *np, *parent_br = NULL;
 	int i, ret;

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

 	if (!ret)
 		parent_br = region_np->parent;

 	/* If overlay has a list of bridges, use it. */
 	if (of_parse_phandle(overlay, "fpga-bridges", 0))
 		np = 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)
 			continue;

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

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

 	return 0;
 }

 /**
  * fpga_region_program_fpga - program FPGA
  * @region: FPGA region
  * @firmware_name: name of FPGA image firmware file
  * @overlay: device node of the overlay
  * Program an FPGA using information in the device tree.
  * Function assumes that there is a firmware-name property.
  * Return 0 for success or negative error code.
  */
 static int fpga_region_program_fpga(struct fpga_region *region,
 				    const char *firmware_name,
 				    struct device_node *overlay)
 {
 	struct fpga_manager *mgr;
 	int ret;

 	region = fpga_region_get(region);
 	if (IS_ERR(region)) {
 		pr_err("failed to get fpga region\n");
 		return PTR_ERR(region);
 	}

 	mgr = fpga_region_get_manager(region);
 	if (IS_ERR(mgr)) {
 		pr_err("failed to get fpga region manager\n");
 		ret = PTR_ERR(mgr);
 		goto err_put_region;
 	}

 	ret = fpga_region_get_bridges(region, overlay);
 	if (ret) {
 		pr_err("failed to get fpga region bridges\n");
 		goto err_put_mgr;
 	}

 	ret = fpga_bridges_disable(&region->bridge_list);
 	if (ret) {
 		pr_err("failed to disable region bridges\n");
 		goto err_put_br;
 	}

 	ret = fpga_mgr_firmware_load(mgr, region->info, firmware_name);
 	if (ret) {
 		pr_err("failed to load fpga image\n");
 		goto err_put_br;
 	}

 	ret = fpga_bridges_enable(&region->bridge_list);
 	if (ret) {
 		pr_err("failed to enable region bridges\n");
 		goto err_put_br;
 	}

 	fpga_mgr_put(mgr);
 	fpga_region_put(region);

 	return 0;

 err_put_br:
 	fpga_bridges_put(&region->bridge_list);
 err_put_mgr:
 	fpga_mgr_put(mgr);
 err_put_region:
 	fpga_region_put(region);

 	return ret;
 }

 /**
  * 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;
 }

 /**
  * fpga_region_notify_pre_apply - pre-apply overlay notification
  *
  * @region: FPGA region that the overlay was applied to
  * @nd: overlay notification data
  *
  * Called after when an overlay targeted to a FPGA Region is about to be
  * applied.  Function will check the properties that will be added to the FPGA
  * region.  If the checks pass, it will program the FPGA.
  *
  * The checks are:
  * The overlay must add either firmware-name or external-fpga-config property
  * to the FPGA Region.
  *
  *   firmware-name         : program the FPGA
  *   external-fpga-config  : FPGA is already programmed
  *   encrypted-fpga-config : FPGA bitstream is encrypted
  *
  * The overlay can add other FPGA regions, but child FPGA regions cannot have a
  * firmware-name property since those regions don't exist yet.
  *
  * If the overlay that breaks the rules, notifier returns an error and the
  * overlay is rejected before it goes into the main tree.
  *
  * Returns 0 for success or negative error code for failure.
  */
 static int fpga_region_notify_pre_apply(struct fpga_region *region,
 					struct of_overlay_notify_data *nd)
 {
 	const char *firmware_name = NULL;
 	struct fpga_image_info *info;
 	int ret;

 	info = devm_kzalloc(&region->dev, sizeof(*info), GFP_KERNEL);
 	if (!info)
 		return -ENOMEM;

 	region->info = info;

 	/* Reject overlay if child FPGA Regions have firmware-name property */
 	ret = child_regions_with_firmware(nd->overlay);
 	if (ret)
 		return ret;

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

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

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

 	of_property_read_string(nd->overlay, "firmware-name", &firmware_name);

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

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

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

 	/* If FPGA was externally programmed, don't specify firmware */
 	if ((info->flags & FPGA_MGR_EXTERNAL_CONFIG) && firmware_name) {
 		pr_err("error: specified firmware and external-fpga-config");
 		return -EINVAL;
 	}

 	/* FPGA is already configured externally.  We're done. */
 	if (info->flags & FPGA_MGR_EXTERNAL_CONFIG)
 		return 0;

 	/* If we got this far, we should be programming the FPGA */
 	if (!firmware_name) {
 		pr_err("should specify firmware-name or external-fpga-config\n");
 		return -EINVAL;
 	}

 	return fpga_region_program_fpga(region, firmware_name, nd->overlay);
 }

 /**
  * 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 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);
 	devm_kfree(&region->dev, 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 = fpga_region_find(nd->target);
 	if (!region)
 		return NOTIFY_OK;

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

 	case OF_OVERLAY_POST_REMOVE:
 		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 fpga_region_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct device_node *np = dev->of_node;
 	struct fpga_region *region;
 	int id, ret = 0;

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

 	id = ida_simple_get(&fpga_region_ida, 0, 0, GFP_KERNEL);
 	if (id < 0) {
 		ret = id;
 		goto err_kfree;
 	}

 	mutex_init(&region->mutex);
 	INIT_LIST_HEAD(&region->bridge_list);

 	device_initialize(&region->dev);
 	region->dev.class = fpga_region_class;
 	region->dev.parent = dev;
 	region->dev.of_node = np;
 	region->dev.id = id;
 	dev_set_drvdata(dev, region);

 	ret = dev_set_name(&region->dev, "region%d", id);
 	if (ret)
 		goto err_remove;

 	ret = device_add(&region->dev);
 	if (ret)
 		goto err_remove;

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

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

 	return 0;

 err_remove:
 	ida_simple_remove(&fpga_region_ida, id);
 err_kfree:
 	kfree(region);

 	return ret;
 }

 static int fpga_region_remove(struct platform_device *pdev)
 {
 	struct fpga_region *region = platform_get_drvdata(pdev);

 	device_unregister(&region->dev);

 	return 0;
 }

 static struct platform_driver fpga_region_driver = {
 	.probe = fpga_region_probe,
 	.remove = fpga_region_remove,
 	.driver = {
 		.name	= "fpga-region",
 		.of_match_table = of_match_ptr(fpga_region_of_match),
 	},
 };

 static void fpga_region_dev_release(struct device *dev)
 {
 	struct fpga_region *region = to_fpga_region(dev);

 	ida_simple_remove(&fpga_region_ida, region->dev.id);
 	kfree(region);
 }

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

 	fpga_region_class = class_create(THIS_MODULE, "fpga_region");
 	if (IS_ERR(fpga_region_class))
 		return PTR_ERR(fpga_region_class);

 	fpga_region_class->dev_release = fpga_region_dev_release;

 	ret = of_overlay_notifier_register(&fpga_region_of_nb);
 	if (ret)
 		goto err_class;

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

 	return 0;

 err_plat:
 	of_overlay_notifier_unregister(&fpga_region_of_nb);
 err_class:
 	class_destroy(fpga_region_class);
 	ida_destroy(&fpga_region_ida);
 	return ret;
 }

 static void __exit fpga_region_exit(void)
 {
 	platform_driver_unregister(&fpga_region_driver);
 	of_overlay_notifier_unregister(&fpga_region_of_nb);
 	class_destroy(fpga_region_class);
 	ida_destroy(&fpga_region_ida);
 }

 subsys_initcall(fpga_region_init);
 module_exit(fpga_region_exit);

 MODULE_DESCRIPTION("FPGA Region");
 MODULE_AUTHOR("Alan Tull <atull@opensource.altera.com>");
 MODULE_LICENSE("GPL v2");
	/*
	* FPGA Region - Device Tree support for FPGA programming under Linux
	*
	* Copyright (C) 2013-2016 Altera Corporation
	*
	* This program is free software; you can redistribute it and/or modify it
	* under the terms and conditions of the GNU General Public License,
	* version 2, as published by the Free Software Foundation.
	*
	* This program is distributed in the hope it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	* more details.
	*
	* You should have received a copy of the GNU General Public License along with
	* this program. If not, see <http://www.gnu.org/licenses/>.
	*/

	#include <linux/fpga/fpga-bridge.h>
	#include <linux/fpga/fpga-mgr.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>

	/**
	* struct fpga_region - FPGA Region structure
	* @dev: FPGA Region device
	* @mutex: enforces exclusive reference to region
	* @bridge_list: list of FPGA bridges specified in region
	* @info: fpga image specific information
	*/
	struct fpga_region {
	struct device dev;
	struct mutex mutex; /* for exclusive reference to region */
	struct list_head bridge_list;
	struct fpga_image_info *info;
	};

	#define to_fpga_region(d) container_of(d, struct fpga_region, dev)

	static DEFINE_IDA(fpga_region_ida);
	static struct class *fpga_region_class;

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

	static int fpga_region_of_node_match(struct device dev, const void data)
	{
	return dev->of_node == data;
	}

	/**
	* 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 fpga_region_find(struct device_node np)
	{
	struct device *dev;

	dev = class_find_device(fpga_region_class, NULL, np,
	fpga_region_of_node_match);
	if (!dev)
	return NULL;

	return to_fpga_region(dev);
	}

	/**
	* fpga_region_get - get an exclusive reference to a fpga region
	* @region: FPGA Region struct
	*
	* Caller should call fpga_region_put() when done with region.
	*
	* Return fpga_region struct if successful.
	* Return -EBUSY if someone already has a reference to the region.
	* Return -ENODEV if @np is not a FPGA Region.
	*/
	static struct fpga_region fpga_region_get(struct fpga_region region)
	{
	struct device *dev = &region->dev;

	if (!mutex_trylock(&region->mutex)) {
	dev_dbg(dev, "%s: FPGA Region already in use\n", __func__);
	return ERR_PTR(-EBUSY);
	}

	get_device(dev);
	of_node_get(dev->of_node);
	if (!try_module_get(dev->parent->driver->owner)) {
	of_node_put(dev->of_node);
	put_device(dev);
	mutex_unlock(&region->mutex);
	return ERR_PTR(-ENODEV);
	}

	dev_dbg(&region->dev, "get\n");

	return region;
	}

	/**
	* fpga_region_put - release a reference to a region
	*
	* @region: FPGA region
	*/
	static void fpga_region_put(struct fpga_region *region)
	{
	struct device *dev = &region->dev;

	dev_dbg(&region->dev, "put\n");

	module_put(dev->parent->driver->owner);
	of_node_put(dev->of_node);
	put_device(dev);
	mutex_unlock(&region->mutex);
	}

	/**
	* fpga_region_get_manager - get exclusive reference for FPGA manager
	* @region: 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 fpga_region_get_manager(struct fpga_region region)
	{
	struct device *dev = &region->dev;
	struct device_node *np = dev->of_node;
	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(np);
	return mgr;
	}
	}
	np = of_get_next_parent(np);
	}
	of_node_put(np);

	return ERR_PTR(-EINVAL);
	}

	/**
	* fpga_region_get_bridges - create a list of bridges
	* @region: FPGA region
	* @overlay: device node of the overlay
	*
	* 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 fpga_region_get_bridges(struct fpga_region *region,
	struct device_node *overlay)
	{
	struct device *dev = &region->dev;
	struct device_node *region_np = dev->of_node;
	struct device_node br, np, *parent_br = NULL;
	int i, ret;

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

	if (!ret)
	parent_br = region_np->parent;

	/* If overlay has a list of bridges, use it. */
	if (of_parse_phandle(overlay, "fpga-bridges", 0))
	np = 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)
	continue;

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

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

	return 0;
	}

	/**
	* fpga_region_program_fpga - program FPGA
	* @region: FPGA region
	* @firmware_name: name of FPGA image firmware file
	* @overlay: device node of the overlay
	* Program an FPGA using information in the device tree.
	* Function assumes that there is a firmware-name property.
	* Return 0 for success or negative error code.
	*/
	static int fpga_region_program_fpga(struct fpga_region *region,
	const char *firmware_name,
	struct device_node *overlay)
	{
	struct fpga_manager *mgr;
	int ret;

	region = fpga_region_get(region);
	if (IS_ERR(region)) {
	pr_err("failed to get fpga region\n");
	return PTR_ERR(region);
	}

	mgr = fpga_region_get_manager(region);
	if (IS_ERR(mgr)) {
	pr_err("failed to get fpga region manager\n");
	ret = PTR_ERR(mgr);
	goto err_put_region;
	}

	ret = fpga_region_get_bridges(region, overlay);
	if (ret) {
	pr_err("failed to get fpga region bridges\n");
	goto err_put_mgr;
	}

	ret = fpga_bridges_disable(&region->bridge_list);
	if (ret) {
	pr_err("failed to disable region bridges\n");
	goto err_put_br;
	}

	ret = fpga_mgr_firmware_load(mgr, region->info, firmware_name);
	if (ret) {
	pr_err("failed to load fpga image\n");
	goto err_put_br;
	}

	ret = fpga_bridges_enable(&region->bridge_list);
	if (ret) {
	pr_err("failed to enable region bridges\n");
	goto err_put_br;
	}

	fpga_mgr_put(mgr);
	fpga_region_put(region);

	return 0;

	err_put_br:
	fpga_bridges_put(&region->bridge_list);
	err_put_mgr:
	fpga_mgr_put(mgr);
	err_put_region:
	fpga_region_put(region);

	return ret;
	}

	/**
	* 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;
	}

	/**
	* fpga_region_notify_pre_apply - pre-apply overlay notification
	*
	* @region: FPGA region that the overlay was applied to
	* @nd: overlay notification data
	*
	* Called after when an overlay targeted to a FPGA Region is about to be
	* applied. Function will check the properties that will be added to the FPGA
	* region. If the checks pass, it will program the FPGA.
	*
	* The checks are:
	* The overlay must add either firmware-name or external-fpga-config property
	* to the FPGA Region.
	*
	* firmware-name : program the FPGA
	* external-fpga-config : FPGA is already programmed
	* encrypted-fpga-config : FPGA bitstream is encrypted
	*
	* The overlay can add other FPGA regions, but child FPGA regions cannot have a
	* firmware-name property since those regions don't exist yet.
	*
	* If the overlay that breaks the rules, notifier returns an error and the
	* overlay is rejected before it goes into the main tree.
	*
	* Returns 0 for success or negative error code for failure.
	*/
	static int fpga_region_notify_pre_apply(struct fpga_region *region,
	struct of_overlay_notify_data *nd)
	{
	const char *firmware_name = NULL;
	struct fpga_image_info *info;
	int ret;

	info = devm_kzalloc(&region->dev, sizeof(*info), GFP_KERNEL);
	if (!info)
	return -ENOMEM;

	region->info = info;

	/* Reject overlay if child FPGA Regions have firmware-name property */
	ret = child_regions_with_firmware(nd->overlay);
	if (ret)
	return ret;

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

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

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

	of_property_read_string(nd->overlay, "firmware-name", &firmware_name);

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

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

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

	/* If FPGA was externally programmed, don't specify firmware */
	if ((info->flags & FPGA_MGR_EXTERNAL_CONFIG) && firmware_name) {
	pr_err("error: specified firmware and external-fpga-config");
	return -EINVAL;
	}

	/* FPGA is already configured externally. We're done. */
	if (info->flags & FPGA_MGR_EXTERNAL_CONFIG)
	return 0;

	/* If we got this far, we should be programming the FPGA */
	if (!firmware_name) {
	pr_err("should specify firmware-name or external-fpga-config\n");
	return -EINVAL;
	}

	return fpga_region_program_fpga(region, firmware_name, nd->overlay);
	}

	/**
	* 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 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);
	devm_kfree(&region->dev, 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 = fpga_region_find(nd->target);
	if (!region)
	return NOTIFY_OK;

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

	case OF_OVERLAY_POST_REMOVE:
	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 fpga_region_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct device_node *np = dev->of_node;
	struct fpga_region *region;
	int id, ret = 0;

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

	id = ida_simple_get(&fpga_region_ida, 0, 0, GFP_KERNEL);
	if (id < 0) {
	ret = id;
	goto err_kfree;
	}

	mutex_init(&region->mutex);
	INIT_LIST_HEAD(&region->bridge_list);

	device_initialize(&region->dev);
	region->dev.class = fpga_region_class;
	region->dev.parent = dev;
	region->dev.of_node = np;
	region->dev.id = id;
	dev_set_drvdata(dev, region);

	ret = dev_set_name(&region->dev, "region%d", id);
	if (ret)
	goto err_remove;

	ret = device_add(&region->dev);
	if (ret)
	goto err_remove;

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

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

	return 0;

	err_remove:
	ida_simple_remove(&fpga_region_ida, id);
	err_kfree:
	kfree(region);

	return ret;
	}

	static int fpga_region_remove(struct platform_device *pdev)
	{
	struct fpga_region *region = platform_get_drvdata(pdev);

	device_unregister(&region->dev);

	return 0;
	}

	static struct platform_driver fpga_region_driver = {
	.probe = fpga_region_probe,
	.remove = fpga_region_remove,
	.driver = {
	.name = "fpga-region",
	.of_match_table = of_match_ptr(fpga_region_of_match),
	},
	};

	static void fpga_region_dev_release(struct device *dev)
	{
	struct fpga_region *region = to_fpga_region(dev);

	ida_simple_remove(&fpga_region_ida, region->dev.id);
	kfree(region);
	}

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

	fpga_region_class = class_create(THIS_MODULE, "fpga_region");
	if (IS_ERR(fpga_region_class))
	return PTR_ERR(fpga_region_class);

	fpga_region_class->dev_release = fpga_region_dev_release;

	ret = of_overlay_notifier_register(&fpga_region_of_nb);
	if (ret)
	goto err_class;

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

	return 0;

	err_plat:
	of_overlay_notifier_unregister(&fpga_region_of_nb);
	err_class:
	class_destroy(fpga_region_class);
	ida_destroy(&fpga_region_ida);
	return ret;
	}

	static void __exit fpga_region_exit(void)
	{
	platform_driver_unregister(&fpga_region_driver);
	of_overlay_notifier_unregister(&fpga_region_of_nb);
	class_destroy(fpga_region_class);
	ida_destroy(&fpga_region_ida);
	}

	subsys_initcall(fpga_region_init);
	module_exit(fpga_region_exit);

	MODULE_DESCRIPTION("FPGA Region");
	MODULE_AUTHOR("Alan Tull <atull@opensource.altera.com>");
	MODULE_LICENSE("GPL v2");