linux-kernel - Re: [RFC PATCH 2/4] fpga: add fake FPGA region

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Message-ID: <Y/Ckw+F/sb2er2oK@yilunxu-OptiPlex-7050>
Date:   Sat, 18 Feb 2023 18:13:23 +0800
From:   Xu Yilun <yilun.xu@...el.com>
To:     Marco Pagani <marpagan@...hat.com>
Cc:     linux-fpga@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 2/4] fpga: add fake FPGA region

On 2023-02-03 at 18:06:51 +0100, Marco Pagani wrote:
> Add fake FPGA region platform driver with support functions. This
> module is part of the KUnit test suite for the FPGA subsystem.
> 
> Signed-off-by: Marco Pagani <marpagan@...hat.com>
> ---
>  drivers/fpga/tests/fake-fpga-region.c | 186 ++++++++++++++++++++++++++
>  drivers/fpga/tests/fake-fpga-region.h |  37 +++++
>  2 files changed, 223 insertions(+)
>  create mode 100644 drivers/fpga/tests/fake-fpga-region.c
>  create mode 100644 drivers/fpga/tests/fake-fpga-region.h
> 
> diff --git a/drivers/fpga/tests/fake-fpga-region.c b/drivers/fpga/tests/fake-fpga-region.c
> new file mode 100644
> index 000000000000..095397e41837
> --- /dev/null
> +++ b/drivers/fpga/tests/fake-fpga-region.c
> @@ -0,0 +1,186 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Driver for fake FPGA region
> + *
> + * Copyright (C) 2023 Red Hat, Inc. All rights reserved.
> + *
> + * Author: Marco Pagani <marpagan@...hat.com>
> + */
> +
> +#include <linux/device.h>
> +#include <linux/platform_device.h>
> +#include <linux/fpga/fpga-mgr.h>
> +#include <linux/fpga/fpga-region.h>
> +#include <linux/fpga/fpga-bridge.h>
> +#include <kunit/test.h>
> +
> +#include "fake-fpga-region.h"
> +
> +#define FAKE_FPGA_REGION_DEV_NAME	"fake_fpga_region"
> +
> +struct fake_region_priv {
> +	int id;
> +	struct kunit *test;
> +};
> +
> +struct fake_region_data {
> +	struct fpga_manager *mgr;
> +	struct kunit *test;
> +};
> +
> +/**
> + * fake_fpga_region_register - register a fake FPGA region
> + * @region_ctx: fake FPGA region context data structure.
> + * @test: KUnit test context object.
> + *
> + * Return: 0 if registration succeeded, an error code otherwise.
> + */
> +int fake_fpga_region_register(struct fake_fpga_region *region_ctx,
> +			      struct fpga_manager *mgr, struct kunit *test)
> +{
> +	struct fake_region_data pdata;
> +	struct fake_region_priv *priv;
> +	int ret;
> +
> +	pdata.mgr = mgr;
> +	pdata.test = test;
> +
> +	region_ctx->pdev = platform_device_alloc(FAKE_FPGA_REGION_DEV_NAME,
> +						 PLATFORM_DEVID_AUTO);
> +	if (IS_ERR(region_ctx->pdev)) {
> +		pr_err("Fake FPGA region device allocation failed\n");
> +		return -ENOMEM;
> +	}
> +
> +	platform_device_add_data(region_ctx->pdev, &pdata, sizeof(pdata));
> +
> +	ret = platform_device_add(region_ctx->pdev);
> +	if (ret) {
> +		pr_err("Fake FPGA region device add failed\n");
> +		platform_device_put(region_ctx->pdev);
> +		return ret;
> +	}
> +
> +	region_ctx->region = platform_get_drvdata(region_ctx->pdev);
> +
> +	if (test) {
> +		priv = region_ctx->region->priv;
> +		kunit_info(test, "Fake FPGA region %d registered\n", priv->id);
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(fake_fpga_region_register);
> +
> +/**
> + * fake_fpga_region_unregister - unregister a fake FPGA region
> + * @region_ctx: fake FPGA region context data structure.
> + */
> +void fake_fpga_region_unregister(struct fake_fpga_region *region_ctx)
> +{
> +	struct fake_region_priv *priv;
> +	struct kunit *test;
> +	int id;
> +
> +	priv = region_ctx->region->priv;
> +	test = priv->test;
> +	id = priv->id;
> +
> +	if (region_ctx->pdev) {
> +		platform_device_unregister(region_ctx->pdev);
> +		if (test)
> +			kunit_info(test, "Fake FPGA region %d unregistered\n", id);
> +	}
> +}
> +EXPORT_SYMBOL_GPL(fake_fpga_region_unregister);
> +
> +/**
> + * fake_fpga_region_add_bridge - add a bridge to a fake FPGA region
> + * @region_ctx: fake FPGA region context data structure.
> + * @bridge: FPGA bridge.
> + *
> + * Return: 0 if registration succeeded, an error code otherwise.
> + */
> +int fake_fpga_region_add_bridge(struct fake_fpga_region *region_ctx,
> +				struct fpga_bridge *bridge)
> +{
> +	struct fake_region_priv *priv;
> +	int ret;
> +
> +	priv = region_ctx->region->priv;
> +
> +	ret = fpga_bridge_get_to_list(bridge->dev.parent, NULL,
> +				      &region_ctx->region->bridge_list);
> +
> +	if (priv->test && !ret)
> +		kunit_info(priv->test, "Bridge added to fake FPGA region %d\n",
> +			   priv->id);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(fake_fpga_region_add_bridge);
> +
> +static int fake_fpga_region_probe(struct platform_device *pdev)
> +{
> +	struct device *dev;
> +	struct fpga_region *region;
> +	struct fpga_manager *mgr;
> +	struct fake_region_data *pdata;
> +	struct fake_region_priv *priv;
> +	static int id_count;
> +
> +	dev = &pdev->dev;
> +	pdata = dev_get_platdata(dev);
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	mgr = fpga_mgr_get(pdata->mgr->dev.parent);
> +	if (IS_ERR(mgr))
> +		return PTR_ERR(mgr);
> +
> +	/*
> +	 * No get_bridges() method since the bridges list is
> +	 * pre-built using fake_fpga_region_add_bridge()
> +	 */

This is not the common use for drivers to associate the region & bridge,
Better to realize the get_bridges() method.

Thanks,
Yilun

> +	region = fpga_region_register(dev, mgr, NULL);
> +	if (IS_ERR(region)) {
> +		fpga_mgr_put(mgr);
> +		return PTR_ERR(region);
> +	}
> +
> +	priv->test = pdata->test;
> +	priv->id = id_count++;
> +	region->priv = priv;
> +
> +	platform_set_drvdata(pdev, region);
> +
> +	return 0;
> +}