commit 0551e91e63c6009b71792133e0ef0cff1c0af6dd
Author: Dave Jiang <dave.jiang@intel.com>
Date:   Thu Oct 1 14:13:19 2026 -0700

    TEST ONLY: cxl/test: mock non-PF0 consumer for cxl_get_range_and_link()
    
    Not for submission. Exercises the multi-PF device-link path against the
    cxl_test type-2 accelerator, and self-tests device_link_add() on a no_pm
    supplier across registration.

diff --git a/tools/testing/cxl/test/Kbuild b/tools/testing/cxl/test/Kbuild
index 9a24ddc28488..279d89be4a4d 100644
--- a/tools/testing/cxl/test/Kbuild
+++ b/tools/testing/cxl/test/Kbuild
@@ -6,11 +6,13 @@ obj-m += cxl_mock.o
 obj-m += cxl_mock_mem.o
 obj-m += cxl_translate.o
 obj-m += cxl_mock_accel.o
+obj-m += cxl_mock_pfx.o
 
 cxl_test-y := cxl.o
 cxl_test-y += hmem_test.o
 cxl_mock-y := mock.o
 cxl_mock_mem-y := mem.o
 cxl_mock_accel-y := accel.o
+cxl_mock_pfx-y := pfx.o
 
 KBUILD_CFLAGS := $(filter-out -Wmissing-prototypes -Wmissing-declarations, $(KBUILD_CFLAGS))
diff --git a/tools/testing/cxl/test/pfx.c b/tools/testing/cxl/test/pfx.c
new file mode 100644
index 000000000000..55b752ebe9ca
--- /dev/null
+++ b/tools/testing/cxl/test/pfx.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * TEST ONLY: mock non-PF0 consumer. Its probe links to the region attached
+ * to the cxl_test type-2 accelerator via cxl_get_range_and_link().
+ */
+
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <cxl/cxl.h>
+
+static char *pf0_name = "cxl_type2_accel.0";
+module_param(pf0_name, charp, 0444);
+
+static struct platform_device *pfx_pdev;
+
+static int cxl_mock_pfx_probe(struct platform_device *pdev)
+{
+	struct device *pf0;
+	struct range range;
+	int rc;
+
+	pf0 = bus_find_device_by_name(&platform_bus_type, NULL, pf0_name);
+	if (!pf0) {
+		dev_info(&pdev->dev, "pfx_test: %s not found\n", pf0_name);
+		return -ENODEV;
+	}
+
+	rc = cxl_get_range_and_link(pf0, &pdev->dev, &range);
+	put_device(pf0);
+	if (rc) {
+		dev_info(&pdev->dev, "pfx_test: link rc=%d\n", rc);
+		/* don't let -EPROBE_DEFER requeue us behind the test's back */
+		return rc == -EPROBE_DEFER ? -EAGAIN : rc;
+	}
+
+	dev_info(&pdev->dev, "pfx_test: link rc=0 range=%pra\n", &range);
+	return 0;
+}
+
+static void cxl_mock_pfx_remove(struct platform_device *pdev)
+{
+	dev_info(&pdev->dev, "pfx_test: removed\n");
+}
+
+static struct platform_driver cxl_mock_pfx_driver = {
+	.probe = cxl_mock_pfx_probe,
+	.remove = cxl_mock_pfx_remove,
+	.driver = {
+		.name = "cxl_mock_pfx",
+	},
+};
+
+static void dev_release(struct device *dev)
+{
+	kfree(dev);
+}
+
+/* device_link_add() must refuse a no_pm supplier that is not registered */
+static void devlink_no_pm_selftest(struct device *consumer)
+{
+	struct device_link *link;
+	struct device *sup;
+	int pass = 0;
+
+	sup = kzalloc_obj(*sup);
+	if (!sup)
+		return;
+	device_initialize(sup);
+	sup->release = dev_release;
+	device_set_pm_not_required(sup);
+	dev_set_name(sup, "pfx_test_supplier");
+
+	link = device_link_add(consumer, sup, DL_FLAG_STATELESS);
+	pr_info("pfx_test: no_pm before device_add: link %s\n",
+		link ? "CREATED (FAIL)" : "refused (PASS)");
+	if (link)
+		device_link_del(link);
+	else
+		pass++;
+
+	if (device_add(sup)) {
+		put_device(sup);
+		return;
+	}
+
+	link = device_link_add(consumer, sup, DL_FLAG_STATELESS);
+	pr_info("pfx_test: no_pm after device_add: link %s\n",
+		link ? "created (PASS)" : "REFUSED (FAIL)");
+	if (link) {
+		device_link_del(link);
+		pass++;
+	}
+
+	device_del(sup);
+	link = device_link_add(consumer, sup, DL_FLAG_STATELESS);
+	pr_info("pfx_test: no_pm after device_del: link %s\n",
+		link ? "CREATED (FAIL)" : "refused (PASS)");
+	if (link)
+		device_link_del(link);
+	else
+		pass++;
+
+	put_device(sup);
+	pr_info("pfx_test: no_pm selftest %d/3 passed\n", pass);
+}
+
+static int __init cxl_mock_pfx_init(void)
+{
+	int rc;
+
+	pfx_pdev = platform_device_register_simple("cxl_mock_pfx", 1, NULL, 0);
+	if (IS_ERR(pfx_pdev))
+		return PTR_ERR(pfx_pdev);
+
+	devlink_no_pm_selftest(&pfx_pdev->dev);
+
+	rc = platform_driver_register(&cxl_mock_pfx_driver);
+	if (rc)
+		platform_device_unregister(pfx_pdev);
+	return rc;
+}
+module_init(cxl_mock_pfx_init);
+
+static void __exit cxl_mock_pfx_exit(void)
+{
+	platform_driver_unregister(&cxl_mock_pfx_driver);
+	platform_device_unregister(pfx_pdev);
+}
+module_exit(cxl_mock_pfx_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("cxl_test: TEST ONLY mock non-PF0 consumer");
+MODULE_IMPORT_NS("CXL");