cxl/rch: Prepare for caching the MMIO mapped PCIe AER capability

Prepare cxl_probe_rcrb() for retrieving more than just the component
register block. The RCH AER handling code wants to get back to the AER
capability that happens to be MMIO mapped rather then configuration
cycles.

Move RCRB specific downstream port data, like the RCRB base and the
AER capability offset, into its own data structure ('struct
cxl_rcrb_info') for cxl_probe_rcrb() to fill. Extend 'struct
cxl_dport' to include a 'struct cxl_rcrb_info' attribute.

This centralizes all RCRB scanning in one routine.

Co-developed-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Terry Bowman <terry.bowman@amd.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20230622205523.85375-4-terry.bowman@amd.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

Author: djbw

drivers/cxl/core/core.h

@@ -68,7 +68,9 @@ enum cxl_rcrb {
 	CXL_RCRB_DOWNSTREAM,
 	CXL_RCRB_UPSTREAM,
 };
-resource_size_t __rcrb_to_component(struct device *dev, resource_size_t rcrb,
+struct cxl_rcrb_info;
+resource_size_t __rcrb_to_component(struct device *dev,
+				    struct cxl_rcrb_info *ri,
 				    enum cxl_rcrb which);
 
 extern struct rw_semaphore cxl_dpa_rwsem;

drivers/cxl/core/port.c

@@ -939,7 +939,8 @@ __devm_cxl_add_dport(struct cxl_port *port, struct device *dport_dev,
 		return ERR_PTR(-ENOMEM);
 
 	if (rcrb != CXL_RESOURCE_NONE) {
-		component_reg_phys = __rcrb_to_component(dport_dev, rcrb,
+		dport->rcrb.base = rcrb;
+		component_reg_phys = __rcrb_to_component(dport_dev, &dport->rcrb,
 							 CXL_RCRB_DOWNSTREAM);
 		if (component_reg_phys == CXL_RESOURCE_NONE) {
 			dev_warn(dport_dev, "Invalid Component Registers in RCRB");
@@ -957,7 +958,6 @@ __devm_cxl_add_dport(struct cxl_port *port, struct device *dport_dev,
 	dport->port_id = port_id;
 	dport->component_reg_phys = component_reg_phys;
 	dport->port = port;
-	dport->rcrb = rcrb;
 
 	cond_cxl_root_lock(port);
 	rc = add_dport(port, dport);

drivers/cxl/core/regs.c

@@ -332,10 +332,11 @@ int cxl_find_regblock(struct pci_dev *pdev, enum cxl_regloc_type type,
 }
 EXPORT_SYMBOL_NS_GPL(cxl_find_regblock, CXL);
 
-resource_size_t __rcrb_to_component(struct device *dev, resource_size_t rcrb,
+resource_size_t __rcrb_to_component(struct device *dev, struct cxl_rcrb_info *ri,
 				    enum cxl_rcrb which)
 {
 	resource_size_t component_reg_phys;
+	resource_size_t rcrb = ri->base;
 	void __iomem *addr;
 	u32 bar0, bar1;
 	u16 cmd;
@@ -400,6 +401,6 @@ resource_size_t cxl_rcd_component_reg_phys(struct device *dev,
 {
 	if (!dport->rch)
 		return CXL_RESOURCE_NONE;
-	return __rcrb_to_component(dev, dport->rcrb, CXL_RCRB_UPSTREAM);
+	return __rcrb_to_component(dev, &dport->rcrb, CXL_RCRB_UPSTREAM);
 }
 EXPORT_SYMBOL_NS_GPL(cxl_rcd_component_reg_phys, CXL);

drivers/cxl/cxl.h

@@ -582,20 +582,25 @@ cxl_find_dport_by_dev(struct cxl_port *port, const struct device *dport_dev)
 	return xa_load(&port->dports, (unsigned long)dport_dev);
 }
 
+struct cxl_rcrb_info {
+	resource_size_t base;
+	u16 aer_cap;
+};
+
 /**
  * struct cxl_dport - CXL downstream port
  * @dport: PCI bridge or firmware device representing the downstream link
  * @port_id: unique hardware identifier for dport in decoder target list
  * @component_reg_phys: downstream port component registers
- * @rcrb: base address for the Root Complex Register Block
+ * @rcrb: Data about the Root Complex Register Block layout
  * @rch: Indicate whether this dport was enumerated in RCH or VH mode
  * @port: reference to cxl_port that contains this downstream port
  */
 struct cxl_dport {
 	struct device *dport;
 	int port_id;
 	resource_size_t component_reg_phys;
-	resource_size_t rcrb;
+	struct cxl_rcrb_info rcrb;
 	bool rch;
 	struct cxl_port *port;
 };

tools/testing/cxl/test/mock.c

@@ -271,8 +271,10 @@ struct cxl_dport *__wrap_devm_cxl_add_rch_dport(struct cxl_port *port,
 	if (ops && ops->is_mock_port(dport_dev)) {
 		dport = devm_cxl_add_dport(port, dport_dev, port_id,
 					   CXL_RESOURCE_NONE);
-		if (!IS_ERR(dport))
+		if (!IS_ERR(dport)) {
+			dport->rcrb.base = rcrb;
 			dport->rch = true;
+		}
 	} else
 		dport = devm_cxl_add_rch_dport(port, dport_dev, port_id, rcrb);
 	put_cxl_mock_ops(index);