fpga: fpga-region: device tree control for FPGA

FPGA Regions support programming FPGA under control of the Device
Tree.

Signed-off-by: Alan Tull <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/fpga/Kconfig

···
 
 if FPGA
 
+config FPGA_REGION
+	tristate "FPGA Region"
+	depends on OF && FPGA_BRIDGE
+	help
+	  FPGA Regions allow loading FPGA images under control of
+	  the Device Tree.
+
 config FPGA_MGR_SOCFPGA
 	tristate "Altera SOCFPGA FPGA Manager"
 	depends on ARCH_SOCFPGA

drivers/fpga/Makefile

···
 
 # FPGA Bridge Drivers
 obj-$(CONFIG_FPGA_BRIDGE)		+= fpga-bridge.o
+
+# High Level Interfaces
+obj-$(CONFIG_FPGA_REGION)		+= fpga-region.o

drivers/fpga/fpga-region.c

···
+/*
+ * 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");
+		return PTR_ERR(mgr);
+	}
+
+	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);
+	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: %s",
+		       child_region->full_name);
+
+	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
+ *
+ * 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;
+
+	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);
+
+	/* 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 <[e-mail]>");
+MODULE_LICENSE("GPL v2");

include/linux/fpga/fpga-mgr.h

···
 /*
  * FPGA Manager flags
  * FPGA_MGR_PARTIAL_RECONFIG: do partial reconfiguration if supported
+ * FPGA_MGR_EXTERNAL_CONFIG: FPGA has been configured prior to Linux booting
  */
 #define FPGA_MGR_PARTIAL_RECONFIG	BIT(0)
+#define FPGA_MGR_EXTERNAL_CONFIG	BIT(1)
 
 /**
  * struct fpga_image_info - information specific to a FPGA image