cxl/test: Add mock version of devm_cxl_add_dport_by_dev()

devm_cxl_add_dport_by_dev() outside of cxl_test is done through PCI
hierarchy. However with cxl_test, it needs to be done through the
platform device hierarchy. Add the mock function for
devm_cxl_add_dport_by_dev().

When cxl_core calls a cxl_core exported function and that function is
mocked by cxl_test, the call chain causes a circular dependency issue. Dan
provided a workaround to avoid this issue. Apply the method to changes from
the late dport allocation changes in order to enable cxl-test.

In cxl_core they are defined with "__" added in front of the function. A
macro is used to define the original function names for when non-test
version of the kernel is built. A bit of macros and typedefs are used to
allow mocking of those functions in cxl_test.

Co-developed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Li Ming <ming.li@zohomail.com>
Tested-by: Alison Schofield <alison.schofield@intel.com>
Tested-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

3 files changed, 24 insertions, 5 deletions

diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index e18425f119bd..b07490aa93c7 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -146,8 +146,6 @@ int cxl_port_get_switch_dport_bandwidth(struct cxl_port *port,
 int cxl_ras_init(void);
 void cxl_ras_exit(void);
 int cxl_gpf_port_setup(struct cxl_dport *dport);
-struct cxl_dport *devm_cxl_add_dport_by_dev(struct cxl_port *port,
-					    struct device *dport_dev);
 
 struct cxl_hdm;
 int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm,
diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index 9ec288ed39ae..18825e1505d6 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -41,14 +41,14 @@ static int pci_get_port_num(struct pci_dev *pdev)
 }
 
 /**
- * devm_cxl_add_dport_by_dev - allocate a dport by the dport device
+ * __devm_cxl_add_dport_by_dev - allocate a dport by dport device
  * @port: cxl_port that hosts the dport
  * @dport_dev: 'struct device' of the dport
  *
  * Returns the allocated dport on success or ERR_PTR() of -errno on error
  */
-struct cxl_dport *devm_cxl_add_dport_by_dev(struct cxl_port *port,
-					    struct device *dport_dev)
+struct cxl_dport *__devm_cxl_add_dport_by_dev(struct cxl_port *port,
+					      struct device *dport_dev)
 {
 	struct cxl_register_map map;
 	struct pci_dev *pdev;
@@ -69,6 +69,7 @@ struct cxl_dport *devm_cxl_add_dport_by_dev(struct cxl_port *port,
 	device_lock_assert(&port->dev);
 	return devm_cxl_add_dport(port, dport_dev, port_num, map.resource);
 }
+EXPORT_SYMBOL_NS_GPL(__devm_cxl_add_dport_by_dev, "CXL");
 
 struct cxl_walk_context {
 	struct pci_bus *bus;
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 672f43b7a87f..99d358455032 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -906,6 +906,10 @@ void cxl_coordinates_combine(struct access_coordinate *out,
 			     struct access_coordinate *c2);
 
 bool cxl_endpoint_decoder_reset_detected(struct cxl_port *port);
+struct cxl_dport *devm_cxl_add_dport_by_dev(struct cxl_port *port,
+					    struct device *dport_dev);
+struct cxl_dport *__devm_cxl_add_dport_by_dev(struct cxl_port *port,
+					      struct device *dport_dev);
 
 /*
  * Unit test builds overrides this to __weak, find the 'strong' version
@@ -916,4 +920,20 @@ bool cxl_endpoint_decoder_reset_detected(struct cxl_port *port);
 #endif
 
 u16 cxl_gpf_get_dvsec(struct device *dev);
+
+/*
+ * Declaration for functions that are mocked by cxl_test that are called by
+ * cxl_core. The respective functions are defined as __foo() and called by
+ * cxl_core as foo(). The macros below ensures that those functions would
+ * exist as foo(). See tools/testing/cxl/cxl_core_exports.c and
+ * tools/testing/cxl/exports.h for setting up the mock functions. The dance
+ * is done to avoid a circular dependency where cxl_core calls a function that
+ * ends up being a mock function and goes to * cxl_test where it calls a
+ * cxl_core function.
+ */
+#ifndef CXL_TEST_ENABLE
+#define DECLARE_TESTABLE(x) __##x
+#define devm_cxl_add_dport_by_dev DECLARE_TESTABLE(devm_cxl_add_dport_by_dev)
+#endif
+
 #endif /* __CXL_H__ */