/*
 * 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: %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
 *   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");