cxl/port: Map Port RAS registers

In preparation for CXL VH (Virtual Host) topology protocol error handling,
add RAS capability registered mapping for all ports in a CXL VH topology.
This includes the RAS capabilities of Switch Upstream Ports, Switch
Downstream Ports, Host Bridge Ports ("upstream"), and Root Ports
("downstream")

Update cxl_port_add_dport() to map the upstream RAS capability on first
'dport' attach.

Signed-off-by: Terry Bowman <terry.bowman@amd.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Co-developed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Terry Bowman <terry.bowman@amd.com>
Link: https://patch.msgid.link/20260131000403.2135324-8-dan.j.williams@intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

drivers/cxl/core/ras.c

@@ -166,6 +166,22 @@ void devm_cxl_dport_rch_ras_setup(struct cxl_dport *dport)
 }
 EXPORT_SYMBOL_NS_GPL(devm_cxl_dport_rch_ras_setup, "CXL");
 
+void devm_cxl_port_ras_setup(struct cxl_port *port)
+{
+	struct cxl_register_map *map = &port->reg_map;
+
+	if (!map->component_map.ras.valid) {
+		dev_dbg(&port->dev, "RAS registers not found\n");
+		return;
+	}
+
+	map->host = &port->dev;
+	if (cxl_map_component_regs(map, &port->regs,
+				   BIT(CXL_CM_CAP_CAP_ID_RAS)))
+		dev_dbg(&port->dev, "Failed to map RAS capability\n");
+}
+EXPORT_SYMBOL_NS_GPL(devm_cxl_port_ras_setup, "CXL");
+
 void cxl_handle_cor_ras(struct device *dev, void __iomem *ras_base)
 {
 	void __iomem *addr;

drivers/cxl/cxl.h

@@ -607,6 +607,7 @@ struct cxl_dax_region {
  * @parent_dport: dport that points to this port in the parent
  * @decoder_ida: allocator for decoder ids
  * @reg_map: component and ras register mapping parameters
+ * @regs: mapped component registers
  * @nr_dports: number of entries in @dports
  * @hdm_end: track last allocated HDM decoder instance for allocation ordering
  * @commit_end: cursor to track highest committed decoder for commit ordering
@@ -628,6 +629,7 @@ struct cxl_port {
 	struct cxl_dport *parent_dport;
 	struct ida decoder_ida;
 	struct cxl_register_map reg_map;
+	struct cxl_component_regs regs;
 	int nr_dports;
 	int hdm_end;
 	int commit_end;

drivers/cxl/cxlpci.h

@@ -82,6 +82,7 @@ void cxl_cor_error_detected(struct pci_dev *pdev);
 pci_ers_result_t cxl_error_detected(struct pci_dev *pdev,
 				    pci_channel_state_t state);
 void devm_cxl_dport_rch_ras_setup(struct cxl_dport *dport);
+void devm_cxl_port_ras_setup(struct cxl_port *port);
 #else
 static inline void cxl_cor_error_detected(struct pci_dev *pdev) { }
 
@@ -94,6 +95,10 @@ static inline pci_ers_result_t cxl_error_detected(struct pci_dev *pdev,
 static inline void devm_cxl_dport_rch_ras_setup(struct cxl_dport *dport)
 {
 }
+
+static inline void devm_cxl_port_ras_setup(struct cxl_port *port)
+{
+}
 #endif
 
 #endif /* __CXL_PCI_H__ */

drivers/cxl/port.c

@@ -192,6 +192,12 @@ static struct cxl_dport *cxl_port_add_dport(struct cxl_port *port,
 		rc = devm_cxl_switch_port_decoders_setup(port);
 		if (rc)
 			return ERR_PTR(rc);
+
+		/*
+		 * RAS setup is optional, either driver operation can continue
+		 * on failure, or the device does not implement RAS registers.
+		 */
+		devm_cxl_port_ras_setup(port);
 	}
 
 	dport = devm_cxl_add_dport_by_dev(port, dport_dev);