alistair23-linux/drivers/fpga/fpga-region.c

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

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

struct fpga_region *fpga_region_class_find(
	struct device *start, const void *data,
	int (*match)(struct device *, const void *))
{
	struct device *dev;

	dev = class_find_device(fpga_region_class, start, data, match);
	if (!dev)
		return NULL;

	return to_fpga_region(dev);
}
EXPORT_SYMBOL_GPL(fpga_region_class_find);

/**
 * 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);
	if (!try_module_get(dev->parent->driver->owner)) {
		put_device(dev);
		mutex_unlock(&region->mutex);
		return ERR_PTR(-ENODEV);
	}

	dev_dbg(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(dev, "put\n");

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

/**
 * fpga_region_program_fpga - program FPGA
 * @region: FPGA region
 * Program an FPGA using fpga image info (region->info).
 * If the region has a get_bridges function, the exclusive reference for the
 * bridges will be held if programming succeeds.  This is intended to prevent
 * reprogramming the region until the caller considers it safe to do so.
 * The caller will need to call fpga_bridges_put() before attempting to
 * reprogram the region.
 * Return 0 for success or negative error code.
 */
int fpga_region_program_fpga(struct fpga_region *region)
{
	struct device *dev = &region->dev;
	struct fpga_image_info *info = region->info;
	int ret;

	region = fpga_region_get(region);
	if (IS_ERR(region)) {
		dev_err(dev, "failed to get FPGA region\n");
		return PTR_ERR(region);
	}

	ret = fpga_mgr_lock(region->mgr);
	if (ret) {
		dev_err(dev, "FPGA manager is busy\n");
		goto err_put_region;
	}

	/*
	 * In some cases, we already have a list of bridges in the
	 * fpga region struct.  Or we don't have any bridges.
	 */
	if (region->get_bridges) {
		ret = region->get_bridges(region);
		if (ret) {
			dev_err(dev, "failed to get fpga region bridges\n");
			goto err_unlock_mgr;
		}
	}

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

	ret = fpga_mgr_load(region->mgr, info);
	if (ret) {
		dev_err(dev, "failed to load FPGA image\n");
		goto err_put_br;
	}

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

	fpga_mgr_unlock(region->mgr);
	fpga_region_put(region);

	return 0;

err_put_br:
	if (region->get_bridges)
		fpga_bridges_put(&region->bridge_list);
err_unlock_mgr:
	fpga_mgr_unlock(region->mgr);
err_put_region:
	fpga_region_put(region);

	return ret;
}
EXPORT_SYMBOL_GPL(fpga_region_program_fpga);

int fpga_region_register(struct device *dev, struct fpga_region *region)
{
	int id, ret = 0;

	id = ida_simple_get(&fpga_region_ida, 0, 0, GFP_KERNEL);
	if (id < 0)
		return id;

	mutex_init(&region->mutex);
	INIT_LIST_HEAD(&region->bridge_list);
	device_initialize(&region->dev);
	region->dev.groups = region->groups;
	region->dev.class = fpga_region_class;
	region->dev.parent = dev;
	region->dev.of_node = dev->of_node;
	region->dev.id = id;

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

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

	return 0;

err_remove:
	ida_simple_remove(&fpga_region_ida, id);
	return ret;
}
EXPORT_SYMBOL_GPL(fpga_region_register);

int fpga_region_unregister(struct fpga_region *region)
{
	device_unregister(&region->dev);

	return 0;
}
EXPORT_SYMBOL_GPL(fpga_region_unregister);

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);
}

/**
 * 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)
{
	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;

	return 0;
}

static void __exit fpga_region_exit(void)
{
	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@kernel.org>");
MODULE_LICENSE("GPL v2");