1 files changed, 48 insertions, 9 deletions

diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index 945ca0304d68..99a75c54ee39 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -274,12 +274,60 @@ static int cxl_pci_setup_mailbox(struct cxl_dev_state *cxlds)
 	return 0;
 }
 
+/*
+ * Assume that any RCIEP that emits the CXL memory expander class code
+ * is an RCD
+ */
+static bool is_cxl_restricted(struct pci_dev *pdev)
+{
+	return pci_pcie_type(pdev) == PCI_EXP_TYPE_RC_END;
+}
+
+static int cxl_rcrb_get_comp_regs(struct pci_dev *pdev,
+				  struct cxl_register_map *map)
+{
+	struct cxl_port *port;
+	struct cxl_dport *dport;
+	resource_size_t component_reg_phys;
+
+	*map = (struct cxl_register_map) {
+		.dev = &pdev->dev,
+		.resource = CXL_RESOURCE_NONE,
+	};
+
+	port = cxl_pci_find_port(pdev, &dport);
+	if (!port)
+		return -EPROBE_DEFER;
+
+	component_reg_phys = cxl_rcd_component_reg_phys(&pdev->dev, dport);
+
+	put_device(&port->dev);
+
+	if (component_reg_phys == CXL_RESOURCE_NONE)
+		return -ENXIO;
+
+	map->resource = component_reg_phys;
+	map->reg_type = CXL_REGLOC_RBI_COMPONENT;
+	map->max_size = CXL_COMPONENT_REG_BLOCK_SIZE;
+
+	return 0;
+}
+
 static int cxl_pci_setup_regs(struct pci_dev *pdev, enum cxl_regloc_type type,
 			      struct cxl_register_map *map)
 {
 	int rc;
 
 	rc = cxl_find_regblock(pdev, type, map);
+
+	/*
+	 * If the Register Locator DVSEC does not exist, check if it
+	 * is an RCH and try to extract the Component Registers from
+	 * an RCRB.
+	 */
+	if (rc && type == CXL_REGLOC_RBI_COMPONENT && is_cxl_restricted(pdev))
+		rc = cxl_rcrb_get_comp_regs(pdev, map);
+
 	if (rc)
 		return rc;
 
@@ -287,15 +335,6 @@ static int cxl_pci_setup_regs(struct pci_dev *pdev, enum cxl_regloc_type type,
 }
 
 /*
- * Assume that any RCIEP that emits the CXL memory expander class code
- * is an RCD
- */
-static bool is_cxl_restricted(struct pci_dev *pdev)
-{
-	return pci_pcie_type(pdev) == PCI_EXP_TYPE_RC_END;
-}
-
-/*
  * CXL v3.0 6.2.3 Table 6-4
  * The table indicates that if PCIe Flit Mode is set, then CXL is in 256B flits
  * mode, otherwise it's 68B flits mode.