// SPDX-License-Identifier: GPL-2.0
/*
 * FPGA Region - 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/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 an 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 an 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);

static ssize_t compat_id_show(struct device *dev,
                              struct device_attribute *attr, char *buf)
{
        struct fpga_region *region = to_fpga_region(dev);

        if (!region->compat_id)
                return -ENOENT;

        return sprintf(buf, "%016llx%016llx\n",
                       (unsigned long long)region->compat_id->id_h,
                       (unsigned long long)region->compat_id->id_l);
}

static DEVICE_ATTR_RO(compat_id);

static struct attribute *fpga_region_attrs[] = {
        &dev_attr_compat_id.attr,
        NULL,
};
ATTRIBUTE_GROUPS(fpga_region);

/**
 * fpga_region_register_full - create and register an FPGA Region device
 * @parent: device parent
 * @info: parameters for FPGA Region
 *
 * Return: struct fpga_region or ERR_PTR()
 */
struct fpga_region *
fpga_region_register_full(struct device *parent, const struct fpga_region_info *info)
{
        struct fpga_region *region;
        int id, ret = 0;

        if (!info) {
                dev_err(parent,
                        "Attempt to register without required info structure\n");
                return ERR_PTR(-EINVAL);
        }

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

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

        region->mgr = info->mgr;
        region->compat_id = info->compat_id;
        region->priv = info->priv;
        region->get_bridges = info->get_bridges;

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

        region->dev.class = fpga_region_class;
        region->dev.parent = parent;
        region->dev.of_node = parent->of_node;
        region->dev.id = id;

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

        ret = device_register(&region->dev);
        if (ret) {
                put_device(&region->dev);
                return ERR_PTR(ret);
        }

        return region;

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

        return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(fpga_region_register_full);

/**
 * fpga_region_register - create and register an FPGA Region device
 * @parent: device parent
 * @mgr: manager that programs this region
 * @get_bridges: optional function to get bridges to a list
 *
 * This simple version of the register function should be sufficient for most users.
 * The fpga_region_register_full() function is available for users that need to
 * pass additional, optional parameters.
 *
 * Return: struct fpga_region or ERR_PTR()
 */
struct fpga_region *
fpga_region_register(struct device *parent, struct fpga_manager *mgr,
                     int (*get_bridges)(struct fpga_region *))
{
        struct fpga_region_info info = { 0 };

        info.mgr = mgr;
        info.get_bridges = get_bridges;

        return fpga_region_register_full(parent, &info);
}
EXPORT_SYMBOL_GPL(fpga_region_register);

/**
 * fpga_region_unregister - unregister an FPGA region
 * @region: FPGA region
 *
 * This function is intended for use in an FPGA region driver's remove function.
 */
void fpga_region_unregister(struct fpga_region *region)
{
        device_unregister(&region->dev);
}
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);
        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)
{
        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_groups = fpga_region_groups;
        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");