Add a kunit test suite for fw_devlink support for software nodes.

Most cases call add_links() directly and inspect the resulting fwnode
supplier/consumer lists: a single reference, multiple references, a
reference to an unregistered node, a "remote-endpoint" reference and a
reference array. The last case is end-to-end - it registers real consumer
and supplier platform devices together with their drivers, adds the
consumer first and checks that fw_devlink defers its probe until the
supplier has been bound.

Signed-off-by: Bartosz Golaszewski <[email protected]>
---
 drivers/base/test/Kconfig               |   5 +
 drivers/base/test/Makefile              |   3 +
 drivers/base/test/swnode-devlink-test.c | 336 ++++++++++++++++++++++++++++++++
 3 files changed, 344 insertions(+)

diff --git a/drivers/base/test/Kconfig b/drivers/base/test/Kconfig
index 
2756870615ccab67ec26d8671c1e4dba69342134..1ecf0791241a1b2eee7e1e787772217724abacb9
 100644
--- a/drivers/base/test/Kconfig
+++ b/drivers/base/test/Kconfig
@@ -18,3 +18,8 @@ config DRIVER_PE_KUNIT_TEST
        tristate "KUnit Tests for property entry API" if !KUNIT_ALL_TESTS
        depends on KUNIT
        default KUNIT_ALL_TESTS
+
+config DRIVER_SWNODE_KUNIT_TEST
+       tristate "KUnit Tests for software node fw_devlink links" if 
!KUNIT_ALL_TESTS
+       depends on KUNIT
+       default KUNIT_ALL_TESTS
diff --git a/drivers/base/test/Makefile b/drivers/base/test/Makefile
index 
e321dfc7e92266d2073d442f652cadb6e911dba5..1b78a705983c145e29bd166606f2c78682342735
 100644
--- a/drivers/base/test/Makefile
+++ b/drivers/base/test/Makefile
@@ -6,3 +6,6 @@ obj-$(CONFIG_DM_KUNIT_TEST)     += platform-device-test.o
 
 obj-$(CONFIG_DRIVER_PE_KUNIT_TEST) += property-entry-test.o
 CFLAGS_property-entry-test.o += $(DISABLE_STRUCTLEAK_PLUGIN)
+
+obj-$(CONFIG_DRIVER_SWNODE_KUNIT_TEST) += swnode-devlink-test.o
+CFLAGS_swnode-devlink-test.o += $(DISABLE_STRUCTLEAK_PLUGIN)
diff --git a/drivers/base/test/swnode-devlink-test.c 
b/drivers/base/test/swnode-devlink-test.c
new file mode 100644
index 
0000000000000000000000000000000000000000..42816f8f7c1ee4572b6c87bc91b434c0e0086aa8
--- /dev/null
+++ b/drivers/base/test/swnode-devlink-test.c
@@ -0,0 +1,336 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) Qualcomm Technologies, Inc. and/or its subsidiaries
+ */
+
+#include <linux/device.h>
+#include <linux/fwnode.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/types.h>
+#include <linux/wait.h>
+
+#include <kunit/fwnode.h>
+#include <kunit/platform_device.h>
+#include <kunit/test.h>
+
+static int swnode_count_suppliers(struct fwnode_handle *fwnode)
+{
+       struct fwnode_link *link;
+       int ret = 0;
+
+       /*
+        * The suppliers and consumers lists should typically only be accessed
+        * with the fwnode_link_lock taken but it's private to the driver core.
+        *
+        * These are tests and at this point nobody should be modifying them so
+        * let's just access the list.
+        */
+       list_for_each_entry(link, &fwnode->suppliers, c_hook)
+               ret++;
+
+       return ret;
+}
+
+/* True if a supplier link con->sup exists, checked from both list ends. */
+static bool swnode_has_link(struct fwnode_handle *consumer,
+                           struct fwnode_handle *supplier)
+{
+       bool from_con = false, from_sup = false;
+       struct fwnode_link *link;
+
+       list_for_each_entry(link, &consumer->suppliers, c_hook) {
+               if (link->supplier == supplier && link->consumer == consumer)
+                       from_con = true;
+       }
+
+       list_for_each_entry(link, &supplier->consumers, s_hook) {
+               if (link->supplier == supplier && link->consumer == consumer)
+                       from_sup = true;
+       }
+
+       return from_con && from_sup;
+}
+
+/* A single reference creates exactly one supplier link, on both list ends. */
+static void swnode_devlink_test_single_ref(struct kunit *test)
+{
+       static const struct software_node supp_swnode = {
+               .name = "swnode-devlink-test-supplier"
+       };
+
+       struct fwnode_handle *cons_fwnode, *supp_fwnode;
+       int ret;
+
+       const struct property_entry props[] = {
+               PROPERTY_ENTRY_REF("supplier", &supp_swnode),
+               { }
+       };
+
+       supp_fwnode = kunit_software_node_register(test, &supp_swnode);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, supp_fwnode);
+
+       cons_fwnode = kunit_fwnode_create_software_node(test, props, NULL);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, cons_fwnode);
+
+       ret = fwnode_call_int_op(cons_fwnode, add_links);
+       KUNIT_EXPECT_EQ(test, ret, 0);
+
+       KUNIT_EXPECT_EQ(test, swnode_count_suppliers(cons_fwnode), 1);
+       KUNIT_EXPECT_TRUE(test, swnode_has_link(cons_fwnode, supp_fwnode));
+}
+
+/* Multiple distinct references create multiple supplier links. */
+static void swnode_devlink_test_multiple_refs(struct kunit *test)
+{
+       static const struct software_node supp1_swnode = {
+               .name = "swnode-devlink-test-supplier-1"
+       };
+       static const struct software_node supp2_swnode = {
+               .name = "swnode-devlink-test-supplier-2"
+       };
+       static const struct software_node *supp_nodes[] = {
+               &supp1_swnode, &supp2_swnode, NULL
+       };
+
+       const struct property_entry props[] = {
+               PROPERTY_ENTRY_REF("foo", &supp1_swnode),
+               PROPERTY_ENTRY_REF("bar", &supp2_swnode),
+               { }
+       };
+
+       struct fwnode_handle *fwnode;
+       int ret;
+
+       ret = kunit_software_node_register_node_group(test, supp_nodes);
+       KUNIT_ASSERT_EQ(test, ret, 0);
+
+       fwnode = kunit_fwnode_create_software_node(test, props, NULL);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, fwnode);
+
+       ret = fwnode_call_int_op(fwnode, add_links);
+       KUNIT_EXPECT_EQ(test, ret, 0);
+
+       KUNIT_EXPECT_EQ(test, swnode_count_suppliers(fwnode), 2);
+       KUNIT_EXPECT_TRUE(test, swnode_has_link(fwnode, 
software_node_fwnode(&supp1_swnode)));
+       KUNIT_EXPECT_TRUE(test, swnode_has_link(fwnode, 
software_node_fwnode(&supp2_swnode)));
+}
+
+/* A reference to an unregistered node creates no link (graceful skip). */
+static void swnode_devlink_test_unregistered_ref(struct kunit *test)
+{
+       static const struct software_node supp_swnode = {
+               .name = "swnode-devlink-test-supplier"
+       };
+
+       const struct property_entry props[] = {
+               PROPERTY_ENTRY_REF("supplier", &supp_swnode),
+               { }
+       };
+
+       struct fwnode_handle *fwnode;
+       int ret;
+
+       fwnode = kunit_fwnode_create_software_node(test, props, NULL);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, fwnode);
+
+       ret = fwnode_call_int_op(fwnode, add_links);
+       KUNIT_EXPECT_EQ(test, ret, 0);
+       KUNIT_EXPECT_EQ(test, swnode_count_suppliers(fwnode), 0);
+}
+
+/* Graph "remote-endpoint" references are excluded. */
+static void swnode_devlink_test_remote_endpoint_excluded(struct kunit *test)
+{
+       static const struct software_node ep_swnode = {
+               .name = "swnode-devlink-test-end-point"
+       };
+
+       const struct property_entry props[] = {
+               PROPERTY_ENTRY_REF("remote-endpoint", &ep_swnode),
+               { }
+       };
+
+       struct fwnode_handle *cons_fwnode, *supp_fwnode;
+       int ret;
+
+       supp_fwnode = kunit_software_node_register(test, &ep_swnode);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, supp_fwnode);
+
+       cons_fwnode = kunit_fwnode_create_software_node(test, props, NULL);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, cons_fwnode);
+
+       ret = fwnode_call_int_op(cons_fwnode, add_links);
+       KUNIT_EXPECT_EQ(test, ret, 0);
+       KUNIT_EXPECT_EQ(test, swnode_count_suppliers(cons_fwnode), 0);
+}
+
+/* A reference array creates one link per registered element. */
+static void swnode_devlink_test_ref_array(struct kunit *test)
+{
+       static const struct software_node supp1_swnode = {
+               .name = "swnode-devlink-test-supplier-1"
+       };
+       static const struct software_node supp2_swnode = {
+               .name = "swnode-devlink-test-supplier-2"
+       };
+       static const struct software_node *supp_nodes[] = {
+               &supp1_swnode, &supp2_swnode, NULL
+       };
+       static const struct software_node_ref_args refs[] = {
+               SOFTWARE_NODE_REFERENCE(&supp1_swnode),
+               SOFTWARE_NODE_REFERENCE(&supp2_swnode, 4, 2),
+       };
+
+       const struct property_entry props[] = {
+               PROPERTY_ENTRY_REF_ARRAY("suppliers", refs),
+               { }
+       };
+
+       struct fwnode_handle *fwnode;
+       int ret;
+
+       ret = kunit_software_node_register_node_group(test, supp_nodes);
+       KUNIT_ASSERT_EQ(test, ret, 0);
+
+       fwnode = kunit_fwnode_create_software_node(test, props, NULL);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, fwnode);
+
+       ret = fwnode_call_int_op(fwnode, add_links);
+       KUNIT_EXPECT_EQ(test, ret, 0);
+
+       KUNIT_EXPECT_EQ(test, swnode_count_suppliers(fwnode), 2);
+       KUNIT_EXPECT_TRUE(test, swnode_has_link(fwnode, 
software_node_fwnode(&supp1_swnode)));
+       KUNIT_EXPECT_TRUE(test, swnode_has_link(fwnode, 
software_node_fwnode(&supp2_swnode)));
+}
+
+/*
+ * End-to-end test: fw_devlink must defer a consumer's probe until its
+ * supplier has probed.
+ *
+ * The reference created by software_node_add_links() is only useful if the
+ * driver core promotes it to a real device_link and uses it to order probing.
+ * This test drives actual probing through the platform bus and asserts the
+ * supplier binds before the consumer.
+ */
+
+#define SWNODE_DEVLINK_TEST_SUPPLIER   "swnode-link-supplier"
+#define SWNODE_DEVLINK_TEST_CONSUMER   "swnode-link-consumer"
+#define SWNODE_DEVLINK_TEST_TIMEOUT_MS 2000
+
+struct swnode_test_probe_order {
+       /* Names in the order their drivers' .probe ran. */
+       const char *probed[2];
+       unsigned int count;
+       wait_queue_head_t wq;
+};
+
+static int swnode_test_record_probe(struct platform_device *pdev)
+{
+       struct swnode_test_probe_order *order = platform_get_drvdata(pdev);
+
+       if (order && order->count < ARRAY_SIZE(order->probed)) {
+               order->probed[order->count++] = dev_name(&pdev->dev);
+               wake_up_interruptible(&order->wq);
+       }
+
+       return 0;
+}
+
+static struct platform_driver swnode_test_supplier_driver = {
+       .probe = swnode_test_record_probe,
+       .driver = {
+               .name = SWNODE_DEVLINK_TEST_SUPPLIER,
+       },
+};
+
+static struct platform_driver swnode_test_consumer_driver = {
+       .probe = swnode_test_record_probe,
+       .driver = {
+               .name = SWNODE_DEVLINK_TEST_CONSUMER,
+       },
+};
+
+static void swnode_devlink_test_probe_order(struct kunit *test)
+{
+       static const struct software_node supplier_swnode = {
+               .name = "swnode-devlink-test-supplier",
+       };
+
+       const struct property_entry consumer_props[] = {
+               PROPERTY_ENTRY_REF("supplier-ref", &supplier_swnode),
+               { }
+       };
+
+       struct platform_device *supplier, *consumer;
+       struct swnode_test_probe_order *order;
+       struct fwnode_handle *fwnode;
+       int ret;
+
+       order = kunit_kzalloc(test, sizeof(*order), GFP_KERNEL);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, order);
+       init_waitqueue_head(&order->wq);
+
+       fwnode = kunit_software_node_register(test, &supplier_swnode);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, fwnode);
+
+       ret = kunit_platform_driver_register(test, 
&swnode_test_supplier_driver);
+       KUNIT_ASSERT_EQ(test, ret, 0);
+       ret = kunit_platform_driver_register(test, 
&swnode_test_consumer_driver);
+       KUNIT_ASSERT_EQ(test, ret, 0);
+
+       supplier = kunit_platform_device_alloc(test, 
SWNODE_DEVLINK_TEST_SUPPLIER,
+                                              PLATFORM_DEVID_NONE);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, supplier);
+       consumer = kunit_platform_device_alloc(test, 
SWNODE_DEVLINK_TEST_CONSUMER,
+                                              PLATFORM_DEVID_NONE);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, consumer);
+
+       platform_set_drvdata(supplier, order);
+       platform_set_drvdata(consumer, order);
+
+       ret = device_add_software_node(&supplier->dev, &supplier_swnode);
+       KUNIT_ASSERT_EQ(test, ret, 0);
+       ret = device_create_managed_software_node(&consumer->dev,
+                                                 consumer_props, NULL);
+       KUNIT_ASSERT_EQ(test, ret, 0);
+
+       ret = kunit_platform_device_add(test, consumer);
+       KUNIT_ASSERT_EQ(test, ret, 0);
+       ret = kunit_platform_device_add(test, supplier);
+       KUNIT_ASSERT_EQ(test, ret, 0);
+
+       ret = wait_event_interruptible_timeout(order->wq,
+                                              order->count == 2,
+                                              
msecs_to_jiffies(SWNODE_DEVLINK_TEST_TIMEOUT_MS));
+       KUNIT_ASSERT_GT(test, ret, 0);
+
+       KUNIT_EXPECT_STREQ(test, order->probed[0], 
SWNODE_DEVLINK_TEST_SUPPLIER);
+       KUNIT_EXPECT_STREQ(test, order->probed[1], 
SWNODE_DEVLINK_TEST_CONSUMER);
+
+       /* Tear down the consumer (and its device link) before the supplier. */
+       kunit_platform_device_unregister(test, consumer);
+
+       device_remove_software_node(&supplier->dev);
+}
+
+static struct kunit_case swnode_test_cases[] = {
+       KUNIT_CASE(swnode_devlink_test_single_ref),
+       KUNIT_CASE(swnode_devlink_test_multiple_refs),
+       KUNIT_CASE(swnode_devlink_test_unregistered_ref),
+       KUNIT_CASE(swnode_devlink_test_remote_endpoint_excluded),
+       KUNIT_CASE(swnode_devlink_test_ref_array),
+       KUNIT_CASE(swnode_devlink_test_probe_order),
+       { }
+};
+
+static struct kunit_suite swnode_test_suite = {
+       .name = "software-node-links",
+       .test_cases = swnode_test_cases,
+};
+
+kunit_test_suite(swnode_test_suite);
+
+MODULE_DESCRIPTION("Test module for software node fw_devlink support");
+MODULE_AUTHOR("Bartosz Golaszewski <[email protected]>");
+MODULE_LICENSE("GPL");

-- 
2.47.3


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