cxl/pci: Store component register base in cxlds

In preparation for defining a cxl_port object to represent the decoder
resources of a memory expander capture the component register base
address.

The port driver uses the component register base to enumerate the HDM
Decoder Capability structure. Unlike other cxl_port objects the endpoint
port decodes from upstream SPA to downstream DPA rather than upstream
port to downstream port.
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
[djbw: clarify changelog]
Link: https://lore.kernel.org/r/164375084181.484304.3919737667590006795.stgit@dwillia2-desk3.amr.corp.intel.comSigned-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/cxl/cxlmem.h

@@ -116,6 +116,7 @@ struct cxl_mbox_cmd {
  * @active_persistent_bytes: sum of hard + soft persistent
  * @next_volatile_bytes: volatile capacity change pending device reset
  * @next_persistent_bytes: persistent capacity change pending device reset
+ * @component_reg_phys: register base of component registers
  * @mbox_send: @dev specific transport for transmitting mailbox commands
  *
  * See section 8.2.9.5.2 Capacity Configuration and Label Storage for
@@ -145,6 +146,8 @@ struct cxl_dev_state {
 	u64 next_volatile_bytes;
 	u64 next_persistent_bytes;
 
+	resource_size_t component_reg_phys;
+
 	int (*mbox_send)(struct cxl_dev_state *cxlds, struct cxl_mbox_cmd *cmd);
 };
 

drivers/cxl/pci.c

@@ -416,6 +416,17 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	if (rc)
 		return rc;
 
+	/*
+	 * If the component registers can't be found, the cxl_pci driver may
+	 * still be useful for management functions so don't return an error.
+	 */
+	cxlds->component_reg_phys = CXL_RESOURCE_NONE;
+	rc = cxl_setup_regs(pdev, CXL_REGLOC_RBI_COMPONENT, &map);
+	if (rc)
+		dev_warn(&pdev->dev, "No component registers (%d)\n", rc);
+
+	cxlds->component_reg_phys = cxl_regmap_to_base(pdev, &map);
+
 	rc = cxl_pci_setup_mailbox(cxlds);
 	if (rc)
 		return rc;