fpga: add an initial KUnit suite for the FPGA Bridge

The suite tests the basic behaviors of the FPGA Bridge including
the functions that operate on a list of bridges.

Signed-off-by: Marco Pagani <marpagan@redhat.com>
Acked-by: Xu Yilun <yilun.xu@intel.com>
Link: https://lore.kernel.org/r/20230718130304.87048-3-marpagan@redhat.com
Signed-off-by: Xu Yilun <yilun.xu@intel.com>

drivers/fpga/tests/fpga-bridge-test.c

@@ -0,0 +1,175 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit test for the FPGA Bridge
+ *
+ * Copyright (C) 2023 Red Hat, Inc.
+ *
+ * Author: Marco Pagani <marpagan@redhat.com>
+ */
+
+#include <kunit/test.h>
+#include <linux/device.h>
+#include <linux/fpga/fpga-bridge.h>
+#include <linux/module.h>
+#include <linux/types.h>
+
+struct bridge_stats {
+	bool enable;
+};
+
+struct bridge_ctx {
+	struct fpga_bridge *bridge;
+	struct platform_device *pdev;
+	struct bridge_stats stats;
+};
+
+static int op_enable_set(struct fpga_bridge *bridge, bool enable)
+{
+	struct bridge_stats *stats = bridge->priv;
+
+	stats->enable = enable;
+
+	return 0;
+}
+
+/*
+ * Fake FPGA bridge that implements only the enable_set op to track
+ * the state.
+ */
+static const struct fpga_bridge_ops fake_bridge_ops = {
+	.enable_set = op_enable_set,
+};
+
+/**
+ * register_test_bridge() - Register a fake FPGA bridge for testing.
+ * @test: KUnit test context object.
+ *
+ * Return: Context of the newly registered FPGA bridge.
+ */
+static struct bridge_ctx *register_test_bridge(struct kunit *test)
+{
+	struct bridge_ctx *ctx;
+
+	ctx = kunit_kzalloc(test, sizeof(*ctx), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
+
+	ctx->pdev = platform_device_register_simple("bridge_pdev", PLATFORM_DEVID_AUTO, NULL, 0);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx->pdev);
+
+	ctx->bridge = fpga_bridge_register(&ctx->pdev->dev, "Fake FPGA bridge", &fake_bridge_ops,
+					   &ctx->stats);
+	KUNIT_ASSERT_FALSE(test, IS_ERR_OR_NULL(ctx->bridge));
+
+	return ctx;
+}
+
+static void unregister_test_bridge(struct bridge_ctx *ctx)
+{
+	fpga_bridge_unregister(ctx->bridge);
+	platform_device_unregister(ctx->pdev);
+}
+
+static void fpga_bridge_test_get(struct kunit *test)
+{
+	struct bridge_ctx *ctx = test->priv;
+	struct fpga_bridge *bridge;
+
+	bridge = fpga_bridge_get(&ctx->pdev->dev, NULL);
+	KUNIT_EXPECT_PTR_EQ(test, bridge, ctx->bridge);
+
+	bridge = fpga_bridge_get(&ctx->pdev->dev, NULL);
+	KUNIT_EXPECT_EQ(test, PTR_ERR(bridge), -EBUSY);
+
+	fpga_bridge_put(ctx->bridge);
+}
+
+static void fpga_bridge_test_toggle(struct kunit *test)
+{
+	struct bridge_ctx *ctx = test->priv;
+	int ret;
+
+	ret = fpga_bridge_disable(ctx->bridge);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_FALSE(test, ctx->stats.enable);
+
+	ret = fpga_bridge_enable(ctx->bridge);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_TRUE(test, ctx->stats.enable);
+}
+
+/* Test the functions for getting and controlling a list of bridges */
+static void fpga_bridge_test_get_put_list(struct kunit *test)
+{
+	struct list_head bridge_list;
+	struct bridge_ctx *ctx_0, *ctx_1;
+	int ret;
+
+	ctx_0 = test->priv;
+	ctx_1 = register_test_bridge(test);
+
+	INIT_LIST_HEAD(&bridge_list);
+
+	/* Get bridge 0 and add it to the list */
+	ret = fpga_bridge_get_to_list(&ctx_0->pdev->dev, NULL, &bridge_list);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+
+	KUNIT_EXPECT_PTR_EQ(test, ctx_0->bridge,
+			    list_first_entry_or_null(&bridge_list, struct fpga_bridge, node));
+
+	/* Get bridge 1 and add it to the list */
+	ret = fpga_bridge_get_to_list(&ctx_1->pdev->dev, NULL, &bridge_list);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+
+	KUNIT_EXPECT_PTR_EQ(test, ctx_1->bridge,
+			    list_first_entry_or_null(&bridge_list, struct fpga_bridge, node));
+
+	/* Disable an then enable both bridges from the list */
+	ret = fpga_bridges_disable(&bridge_list);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+
+	KUNIT_EXPECT_FALSE(test, ctx_0->stats.enable);
+	KUNIT_EXPECT_FALSE(test, ctx_1->stats.enable);
+
+	ret = fpga_bridges_enable(&bridge_list);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+
+	KUNIT_EXPECT_TRUE(test, ctx_0->stats.enable);
+	KUNIT_EXPECT_TRUE(test, ctx_1->stats.enable);
+
+	/* Put and remove both bridges from the list */
+	fpga_bridges_put(&bridge_list);
+
+	KUNIT_EXPECT_TRUE(test, list_empty(&bridge_list));
+
+	unregister_test_bridge(ctx_1);
+}
+
+static int fpga_bridge_test_init(struct kunit *test)
+{
+	test->priv = register_test_bridge(test);
+
+	return 0;
+}
+
+static void fpga_bridge_test_exit(struct kunit *test)
+{
+	unregister_test_bridge(test->priv);
+}
+
+static struct kunit_case fpga_bridge_test_cases[] = {
+	KUNIT_CASE(fpga_bridge_test_get),
+	KUNIT_CASE(fpga_bridge_test_toggle),
+	KUNIT_CASE(fpga_bridge_test_get_put_list),
+	{}
+};
+
+static struct kunit_suite fpga_bridge_suite = {
+	.name = "fpga_bridge",
+	.init = fpga_bridge_test_init,
+	.exit = fpga_bridge_test_exit,
+	.test_cases = fpga_bridge_test_cases,
+};
+
+kunit_test_suite(fpga_bridge_suite);
+
+MODULE_LICENSE("GPL");