cxl/pci: Map RCH downstream AER registers for logging protocol errors

The restricted CXL host (RCH) error handler will log protocol errors
using AER and RAS status registers. The AER and RAS registers need to
be virtually memory mapped before enabling interrupts. Create the
initializer function devm_cxl_setup_parent_dport() for this when the
endpoint is connected with the dport. The initialization sets up the
RCH RAS and AER mappings.

Add 'struct cxl_regs' to 'struct cxl_dport' for saving a pointer to
the RCH downstream port's AER and RAS registers.
Signed-off-by: Terry Bowman <terry.bowman@amd.com>
Co-developed-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Robert Richter <rrichter@amd.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20231018171713.1883517-15-rrichter@amd.comSigned-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/cxl/core/pci.c

@@ -5,6 +5,7 @@
 #include <linux/delay.h>
 #include <linux/pci.h>
 #include <linux/pci-doe.h>
+#include <linux/aer.h>
 #include <cxlpci.h>
 #include <cxlmem.h>
 #include <cxl.h>
@@ -730,6 +731,38 @@ static bool cxl_handle_endpoint_ras(struct cxl_dev_state *cxlds)
 
 #ifdef CONFIG_PCIEAER_CXL
 
+static void cxl_dport_map_rch_aer(struct cxl_dport *dport)
+{
+	struct cxl_rcrb_info *ri = &dport->rcrb;
+	void __iomem *dport_aer = NULL;
+	resource_size_t aer_phys;
+	struct device *host;
+
+	if (dport->rch && ri->aer_cap) {
+		host = dport->reg_map.host;
+		aer_phys = ri->aer_cap + ri->base;
+		dport_aer = devm_cxl_iomap_block(host, aer_phys,
+				sizeof(struct aer_capability_regs));
+	}
+
+	dport->regs.dport_aer = dport_aer;
+}
+
+static void cxl_dport_map_regs(struct cxl_dport *dport)
+{
+	struct cxl_register_map *map = &dport->reg_map;
+	struct device *dev = dport->dport_dev;
+
+	if (!map->component_map.ras.valid)
+		dev_dbg(dev, "RAS registers not found\n");
+	else if (cxl_map_component_regs(map, &dport->regs.component,
+					BIT(CXL_CM_CAP_CAP_ID_RAS)))
+		dev_dbg(dev, "Failed to map RAS capability.\n");
+
+	if (dport->rch)
+		cxl_dport_map_rch_aer(dport);
+}
+
 void cxl_setup_parent_dport(struct device *host, struct cxl_dport *dport)
 {
 	struct device *dport_dev = dport->dport_dev;
@@ -738,6 +771,9 @@ void cxl_setup_parent_dport(struct device *host, struct cxl_dport *dport)
 	host_bridge = to_pci_host_bridge(dport_dev);
 	if (host_bridge->native_cxl_error)
 		dport->rcrb.aer_cap = cxl_rcrb_to_aer(dport_dev, dport->rcrb.base);
+
+	dport->reg_map.host = host;
+	cxl_dport_map_regs(dport);
 }
 EXPORT_SYMBOL_NS_GPL(cxl_setup_parent_dport, CXL);
 

drivers/cxl/cxl.h

@@ -221,6 +221,14 @@ struct cxl_regs {
 	struct_group_tagged(cxl_pmu_regs, pmu_regs,
 		void __iomem *pmu;
 	);
+
+	/*
+	 * RCH downstream port specific RAS register
+	 * @aer: CXL 3.0 8.2.1.1 RCH Downstream Port RCRB
+	 */
+	struct_group_tagged(cxl_rch_regs, rch_regs,
+		void __iomem *dport_aer;
+	);
 };
 
 struct cxl_reg_map {
@@ -623,6 +631,7 @@ struct cxl_rcrb_info {
  * @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
+ * @regs: Dport parsed register blocks
  */
 struct cxl_dport {
 	struct device *dport_dev;
@@ -631,6 +640,7 @@ struct cxl_dport {
 	struct cxl_rcrb_info rcrb;
 	bool rch;
 	struct cxl_port *port;
+	struct cxl_regs regs;
 };
 
 /**