// SPDX-License-Identifier: GPL-2.0
/*
 * FPGA Region - Device Tree 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/of.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

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

/**
 * of_fpga_region_find - find FPGA region
 * @np: device node of FPGA Region
 *
 * Caller will need to put_device(&region->dev) when done.
 *
 * Return: FPGA Region struct or NULL
 */
static struct fpga_region *of_fpga_region_find(struct device_node *np)
{
        return fpga_region_class_find(NULL, np, device_match_of_node);
}

/**
 * of_fpga_region_get_mgr - get reference for FPGA manager
 * @np: device node of 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 *of_fpga_region_get_mgr(struct device_node *np)
{
        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(mgr_node);
                                of_node_put(np);
                                return mgr;
                        }
                }
                np = of_get_next_parent(np);
        }
        of_node_put(np);

        return ERR_PTR(-EINVAL);
}

/**
 * of_fpga_region_get_bridges - create a list of bridges
 * @region: FPGA region
 *
 * 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 an error code if any of the bridges are not available.
 */
static int of_fpga_region_get_bridges(struct fpga_region *region)
{
        struct device *dev = &region->dev;
        struct device_node *region_np = dev->of_node;
        struct fpga_image_info *info = region->info;
        struct device_node *br, *np, *parent_br = NULL;
        int i, ret;

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

        /* -EBUSY means parent is a bridge that is under use. Give up. */
        if (ret == -EBUSY)
                return ret;

        /* Zero return code means parent was a bridge and was added to list. */
        if (!ret)
                parent_br = region_np->parent;

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

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

                /* If any of the bridges are not available, give up */
                if (ret) {
                        fpga_bridges_put(&region->bridge_list);
                        return ret;
                }
        }

        return 0;
}

/**
 * child_regions_with_firmware - Used to check the child region info.
 * @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;
}

/**
 * of_fpga_region_parse_ov - parse and check overlay applied to region
 *
 * @region: FPGA region
 * @overlay: overlay applied to the FPGA region
 *
 * Given an overlay applied to an FPGA region, parse the FPGA image specific
 * info in the overlay and do some checking.
 *
 * Return:
 *   NULL if overlay doesn't direct us to program the FPGA.
 *   fpga_image_info struct if there is an image to program.
 *   error code for invalid overlay.
 */
static struct fpga_image_info *
of_fpga_region_parse_ov(struct fpga_region *region,
                        struct device_node *overlay)
{
        struct device *dev = &region->dev;
        struct fpga_image_info *info;
        const char *firmware_name;
        int ret;

        if (region->info) {
                dev_err(dev, "Region already has overlay applied.\n");
                return ERR_PTR(-EINVAL);
        }

        /*
         * Reject overlay if child FPGA Regions added in the overlay have
         * firmware-name property (would mean that an FPGA region that has
         * not been added to the live tree yet is doing FPGA programming).
         */
        ret = child_regions_with_firmware(overlay);
        if (ret)
                return ERR_PTR(ret);

        info = fpga_image_info_alloc(dev);
        if (!info)
                return ERR_PTR(-ENOMEM);

        info->overlay = overlay;

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

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

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

        if (!of_property_read_string(overlay, "firmware-name",
                                     &firmware_name)) {
                info->firmware_name = devm_kstrdup(dev, firmware_name,
                                                   GFP_KERNEL);
                if (!info->firmware_name)
                        return ERR_PTR(-ENOMEM);
        }

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

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

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

        /* If overlay is not programming the FPGA, don't need FPGA image info */
        if (!info->firmware_name) {
                ret = 0;
                goto ret_no_info;
        }

        /*
         * If overlay informs us FPGA was externally programmed, specifying
         * firmware here would be ambiguous.
         */
        if (info->flags & FPGA_MGR_EXTERNAL_CONFIG) {
                dev_err(dev, "error: specified firmware and external-fpga-config");
                ret = -EINVAL;
                goto ret_no_info;
        }

        return info;
ret_no_info:
        fpga_image_info_free(info);
        return ERR_PTR(ret);
}

/**
 * of_fpga_region_notify_pre_apply - pre-apply overlay notification
 *
 * @region: FPGA region that the overlay was applied to
 * @nd: overlay notification data
 *
 * Called when an overlay targeted to an FPGA Region is about to be applied.
 * Parses the overlay for properties that influence how the FPGA will be
 * programmed and does some checking. If the checks pass, programs the FPGA.
 * If the checks fail, overlay is rejected and does not get added to the
 * live tree.
 *
 * Return: 0 for success or negative error code for failure.
 */
static int of_fpga_region_notify_pre_apply(struct fpga_region *region,
                                           struct of_overlay_notify_data *nd)
{
        struct device *dev = &region->dev;
        struct fpga_image_info *info;
        int ret;

        info = of_fpga_region_parse_ov(region, nd->overlay);
        if (IS_ERR(info))
                return PTR_ERR(info);

        /* If overlay doesn't program the FPGA, accept it anyway. */
        if (!info)
                return 0;

        if (region->info) {
                dev_err(dev, "Region already has overlay applied.\n");
                return -EINVAL;
        }

        region->info = info;
        ret = fpga_region_program_fpga(region);
        if (ret) {
                /* error; reject overlay */
                fpga_image_info_free(info);
                region->info = NULL;
        }

        return ret;
}

/**
 * of_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 of_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);
        fpga_image_info_free(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 an FPGA when a "firmware-name" property is
 * added to an fpga-region.
 *
 * Return: 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 = of_fpga_region_find(nd->target);
        if (!region)
                return NOTIFY_OK;

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

        case OF_OVERLAY_POST_REMOVE:
                of_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 of_fpga_region_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct device_node *np = dev->of_node;
        struct fpga_region *region;
        struct fpga_manager *mgr;
        int ret;

        /* Find the FPGA mgr specified by region or parent region. */
        mgr = of_fpga_region_get_mgr(np);
        if (IS_ERR(mgr))
                return -EPROBE_DEFER;

        region = fpga_region_register(dev, mgr, of_fpga_region_get_bridges);
        if (IS_ERR(region)) {
                ret = PTR_ERR(region);
                goto eprobe_mgr_put;
        }

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

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

        return 0;

eprobe_mgr_put:
        fpga_mgr_put(mgr);
        return ret;
}

static void of_fpga_region_remove(struct platform_device *pdev)
{
        struct fpga_region *region = platform_get_drvdata(pdev);
        struct fpga_manager *mgr = region->mgr;

        fpga_region_unregister(region);
        fpga_mgr_put(mgr);
}

static struct platform_driver of_fpga_region_driver = {
        .probe = of_fpga_region_probe,
        .remove = of_fpga_region_remove,
        .driver = {
                .name   = "of-fpga-region",
                .of_match_table = of_match_ptr(fpga_region_of_match),
        },
};

/**
 * of_fpga_region_init - init function for fpga_region class
 * Creates the fpga_region class and registers a reconfig notifier.
 *
 * Return: 0 on success, negative error code otherwise.
 */
static int __init of_fpga_region_init(void)
{
        int ret;

        ret = of_overlay_notifier_register(&fpga_region_of_nb);
        if (ret)
                return ret;

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

        return 0;

err_plat:
        of_overlay_notifier_unregister(&fpga_region_of_nb);
        return ret;
}

static void __exit of_fpga_region_exit(void)
{
        platform_driver_unregister(&of_fpga_region_driver);
        of_overlay_notifier_unregister(&fpga_region_of_nb);
}

subsys_initcall(of_fpga_region_init);
module_exit(of_fpga_region_exit);

MODULE_DESCRIPTION("FPGA Region");
MODULE_AUTHOR("Alan Tull <atull@kernel.org>");
MODULE_LICENSE("GPL v2");