cxl/test: Refactor decoder setup to reduce cxl_test burden

Group the decoder setup code in switch and endpoint port probe into a
single function for each to reduce the number of functions to be mocked
in cxl_test. Introduce devm_cxl_switch_port_decoders_setup() and
devm_cxl_endpoint_decoders_setup(). These two functions will be mocked
instead with some functions optimized out since the mock version does
not do anything. Remove devm_cxl_setup_hdm(),
devm_cxl_add_passthrough_decoder(), and devm_cxl_enumerate_decoders() in
cxl_test mock code. In turn, mock_cxl_add_passthrough_decoder() can be
removed since cxl_test does not setup passthrough decoders.
__wrap_cxl_hdm_decode_init() and __wrap_cxl_dvsec_rr_decode() can be
removed as well since they only return 0 when called.

[dj: drop 'struct cxl_port' forward declaration (Robert)]

Suggested-by: Robert Richter <rrichter@amd.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

6 files changed, 125 insertions, 52 deletions

diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 2669f251d677..b07490aa93c7 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -147,6 +147,11 @@ int cxl_ras_init(void);
 void cxl_ras_exit(void);
 int cxl_gpf_port_setup(struct cxl_dport *dport);
 
+struct cxl_hdm;
+int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm,
+			struct cxl_endpoint_dvsec_info *info);
+int cxl_port_get_possible_dports(struct cxl_port *port);
+
 #ifdef CONFIG_CXL_FEATURES
 struct cxl_feat_entry *
 cxl_feature_info(struct cxl_features_state *cxlfs, const uuid_t *uuid);
diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index cee68bbc7ff6..78bfe4f55b96 100644
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -49,7 +49,7 @@ static int add_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld)
  * are claimed and passed to the single dport. Disable the range until the first
  * CXL region is enumerated / activated.
  */
-int devm_cxl_add_passthrough_decoder(struct cxl_port *port)
+static int devm_cxl_add_passthrough_decoder(struct cxl_port *port)
 {
 	struct cxl_switch_decoder *cxlsd;
 	struct cxl_dport *dport = NULL;
@@ -75,7 +75,6 @@ int devm_cxl_add_passthrough_decoder(struct cxl_port *port)
 
 	return add_hdm_decoder(port, &cxlsd->cxld);
 }
-EXPORT_SYMBOL_NS_GPL(devm_cxl_add_passthrough_decoder, "CXL");
 
 static void parse_hdm_decoder_caps(struct cxl_hdm *cxlhdm)
 {
@@ -145,8 +144,8 @@ static bool should_emulate_decoders(struct cxl_endpoint_dvsec_info *info)
  * @port: cxl_port to map
  * @info: cached DVSEC range register info
  */
-struct cxl_hdm *devm_cxl_setup_hdm(struct cxl_port *port,
-				   struct cxl_endpoint_dvsec_info *info)
+static struct cxl_hdm *devm_cxl_setup_hdm(struct cxl_port *port,
+					  struct cxl_endpoint_dvsec_info *info)
 {
 	struct cxl_register_map *reg_map = &port->reg_map;
 	struct device *dev = &port->dev;
@@ -201,7 +200,6 @@ struct cxl_hdm *devm_cxl_setup_hdm(struct cxl_port *port,
 
 	return cxlhdm;
 }
-EXPORT_SYMBOL_NS_GPL(devm_cxl_setup_hdm, "CXL");
 
 static void __cxl_dpa_debug(struct seq_file *file, struct resource *r, int depth)
 {
@@ -1166,8 +1164,8 @@ static void cxl_settle_decoders(struct cxl_hdm *cxlhdm)
  * @cxlhdm: Structure to populate with HDM capabilities
  * @info: cached DVSEC range register info
  */
-int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
-				struct cxl_endpoint_dvsec_info *info)
+static int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
+				       struct cxl_endpoint_dvsec_info *info)
 {
 	void __iomem *hdm = cxlhdm->regs.hdm_decoder;
 	struct cxl_port *port = cxlhdm->port;
@@ -1222,4 +1220,71 @@ int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
 
 	return 0;
 }
-EXPORT_SYMBOL_NS_GPL(devm_cxl_enumerate_decoders, "CXL");
+
+/**
+ * devm_cxl_switch_port_decoders_setup - allocate and setup switch decoders
+ * @port: CXL port context
+ *
+ * Return 0 or -errno on error
+ */
+int devm_cxl_switch_port_decoders_setup(struct cxl_port *port)
+{
+	struct cxl_hdm *cxlhdm;
+
+	if (is_cxl_root(port) || is_cxl_endpoint(port))
+		return -EOPNOTSUPP;
+
+	cxlhdm = devm_cxl_setup_hdm(port, NULL);
+	if (!IS_ERR(cxlhdm))
+		return devm_cxl_enumerate_decoders(cxlhdm, NULL);
+
+	if (PTR_ERR(cxlhdm) != -ENODEV) {
+		dev_err(&port->dev, "Failed to map HDM decoder capability\n");
+		return PTR_ERR(cxlhdm);
+	}
+
+	if (cxl_port_get_possible_dports(port) == 1) {
+		dev_dbg(&port->dev, "Fallback to passthrough decoder\n");
+		return devm_cxl_add_passthrough_decoder(port);
+	}
+
+	dev_err(&port->dev, "HDM decoder capability not found\n");
+	return -ENXIO;
+}
+EXPORT_SYMBOL_NS_GPL(devm_cxl_switch_port_decoders_setup, "CXL");
+
+/**
+ * devm_cxl_endpoint_decoders_setup - allocate and setup endpoint decoders
+ * @port: CXL port context
+ *
+ * Return 0 or -errno on error
+ */
+int devm_cxl_endpoint_decoders_setup(struct cxl_port *port)
+{
+	struct cxl_memdev *cxlmd = to_cxl_memdev(port->uport_dev);
+	struct cxl_endpoint_dvsec_info info = { .port = port };
+	struct cxl_dev_state *cxlds = cxlmd->cxlds;
+	struct cxl_hdm *cxlhdm;
+	int rc;
+
+	if (!is_cxl_endpoint(port))
+		return -EOPNOTSUPP;
+
+	rc = cxl_dvsec_rr_decode(cxlds, &info);
+	if (rc < 0)
+		return rc;
+
+	cxlhdm = devm_cxl_setup_hdm(port, &info);
+	if (IS_ERR(cxlhdm)) {
+		if (PTR_ERR(cxlhdm) == -ENODEV)
+			dev_err(&port->dev, "HDM decoder registers not found\n");
+		return PTR_ERR(cxlhdm);
+	}
+
+	rc = cxl_hdm_decode_init(cxlds, cxlhdm, &info);
+	if (rc)
+		return rc;
+
+	return devm_cxl_enumerate_decoders(cxlhdm, &info);
+}
+EXPORT_SYMBOL_NS_GPL(devm_cxl_endpoint_decoders_setup, "CXL");
diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index b50551601c2e..fa02366d35f2 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -1169,3 +1169,45 @@ int cxl_gpf_port_setup(struct cxl_dport *dport)
 
 	return 0;
 }
+
+static int count_dports(struct pci_dev *pdev, void *data)
+{
+	struct cxl_walk_context *ctx = data;
+	int type = pci_pcie_type(pdev);
+
+	if (pdev->bus != ctx->bus)
+		return 0;
+	if (!pci_is_pcie(pdev))
+		return 0;
+	if (type != ctx->type)
+		return 0;
+
+	ctx->count++;
+	return 0;
+}
+
+int cxl_port_get_possible_dports(struct cxl_port *port)
+{
+	struct pci_bus *bus = cxl_port_to_pci_bus(port);
+	struct cxl_walk_context ctx;
+	int type;
+
+	if (!bus) {
+		dev_err(&port->dev, "No PCI bus found for port %s\n",
+			dev_name(&port->dev));
+		return -ENXIO;
+	}
+
+	if (pci_is_root_bus(bus))
+		type = PCI_EXP_TYPE_ROOT_PORT;
+	else
+		type = PCI_EXP_TYPE_DOWNSTREAM;
+
+	ctx = (struct cxl_walk_context) {
+		.bus = bus,
+		.type = type,
+	};
+	pci_walk_bus(bus, count_dports, &ctx);
+
+	return ctx.count;
+}
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 4b858f3d44c6..672f43b7a87f 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -810,12 +810,9 @@ struct cxl_endpoint_dvsec_info {
 	struct range dvsec_range[2];
 };
 
-struct cxl_hdm;
-struct cxl_hdm *devm_cxl_setup_hdm(struct cxl_port *port,
-				   struct cxl_endpoint_dvsec_info *info);
-int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
-				struct cxl_endpoint_dvsec_info *info);
-int devm_cxl_add_passthrough_decoder(struct cxl_port *port);
+int devm_cxl_switch_port_decoders_setup(struct cxl_port *port);
+int devm_cxl_endpoint_decoders_setup(struct cxl_port *port);
+
 struct cxl_dev_state;
 int cxl_dvsec_rr_decode(struct cxl_dev_state *cxlds,
 			struct cxl_endpoint_dvsec_info *info);
diff --git a/drivers/cxl/cxlpci.h b/drivers/cxl/cxlpci.h
index 54e219b0049e..7ae621e618e7 100644
--- a/drivers/cxl/cxlpci.h
+++ b/drivers/cxl/cxlpci.h
@@ -129,8 +129,6 @@ static inline bool cxl_pci_flit_256(struct pci_dev *pdev)
 
 int devm_cxl_port_enumerate_dports(struct cxl_port *port);
 struct cxl_dev_state;
-int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm,
-			struct cxl_endpoint_dvsec_info *info);
 void read_cdat_data(struct cxl_port *port);
 void cxl_cor_error_detected(struct pci_dev *pdev);
 pci_ers_result_t cxl_error_detected(struct pci_dev *pdev,
diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c
index cf32dc50b7a6..d8cae2b5bac6 100644
--- a/drivers/cxl/port.c
+++ b/drivers/cxl/port.c
@@ -59,7 +59,6 @@ static int discover_region(struct device *dev, void *unused)
 
 static int cxl_switch_port_probe(struct cxl_port *port)
 {
-	struct cxl_hdm *cxlhdm;
 	int rc;
 
 	/* Cache the data early to ensure is_visible() works */
@@ -71,43 +70,14 @@ static int cxl_switch_port_probe(struct cxl_port *port)
 
 	cxl_switch_parse_cdat(port);
 
-	cxlhdm = devm_cxl_setup_hdm(port, NULL);
-	if (!IS_ERR(cxlhdm))
-		return devm_cxl_enumerate_decoders(cxlhdm, NULL);
-
-	if (PTR_ERR(cxlhdm) != -ENODEV) {
-		dev_err(&port->dev, "Failed to map HDM decoder capability\n");
-		return PTR_ERR(cxlhdm);
-	}
-
-	if (rc == 1) {
-		dev_dbg(&port->dev, "Fallback to passthrough decoder\n");
-		return devm_cxl_add_passthrough_decoder(port);
-	}
-
-	dev_err(&port->dev, "HDM decoder capability not found\n");
-	return -ENXIO;
+	return devm_cxl_switch_port_decoders_setup(port);
 }
 
 static int cxl_endpoint_port_probe(struct cxl_port *port)
 {
-	struct cxl_endpoint_dvsec_info info = { .port = port };
 	struct cxl_memdev *cxlmd = to_cxl_memdev(port->uport_dev);
-	struct cxl_dev_state *cxlds = cxlmd->cxlds;
-	struct cxl_hdm *cxlhdm;
 	int rc;
 
-	rc = cxl_dvsec_rr_decode(cxlds, &info);
-	if (rc < 0)
-		return rc;
-
-	cxlhdm = devm_cxl_setup_hdm(port, &info);
-	if (IS_ERR(cxlhdm)) {
-		if (PTR_ERR(cxlhdm) == -ENODEV)
-			dev_err(&port->dev, "HDM decoder registers not found\n");
-		return PTR_ERR(cxlhdm);
-	}
-
 	/* Cache the data early to ensure is_visible() works */
 	read_cdat_data(port);
 	cxl_endpoint_parse_cdat(port);
@@ -117,11 +87,7 @@ static int cxl_endpoint_port_probe(struct cxl_port *port)
 	if (rc)
 		return rc;
 
-	rc = cxl_hdm_decode_init(cxlds, cxlhdm, &info);
-	if (rc)
-		return rc;
-
-	rc = devm_cxl_enumerate_decoders(cxlhdm, &info);
+	rc = devm_cxl_endpoint_decoders_setup(port);
 	if (rc)
 		return rc;