cxl/acpi: Probe RCRB later during RCH downstream port creation

The RCRB is extracted already during ACPI CEDT table parsing while the
data of this is needed not earlier than dport creation. This
implementation comes with drawbacks: During ACPI table scan there is
already MMIO access including mapping and unmapping, but only ACPI
data should be collected here. The collected data must be transferred
through a couple of interfaces until it is finally consumed when
creating the dport. This causes complex data structures and function
interfaces. Additionally, RCRB parsing will be extended to also
extract AER data, it would be much easier do this at a later point
during port and dport creation when the data structures are available
to hold that data.

To simplify all that, probe the RCRB at a later point during RCH
downstream port creation. Change ACPI table parser to only extract the
base address of either the component registers or the RCRB. Parse and
extract the RCRB in devm_cxl_add_rch_dport().

This is in preparation to centralize all RCRB scanning.

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/20230622205523.85375-2-terry.bowman@amd.com
Co-developed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/20230622205523.85375-3-terry.bowman@amd.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

6 files changed, 61 insertions, 50 deletions

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index 7e1765b09e04..70cd9ac73a8b 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -372,21 +372,21 @@ static int add_host_bridge_uport(struct device *match, void *arg)
 	return 0;
 }
 
+/* Note, @dev is used by mock_acpi_table_parse_cedt() */
 struct cxl_chbs_context {
 	struct device *dev;
 	unsigned long long uid;
-	resource_size_t rcrb;
-	resource_size_t chbcr;
+	resource_size_t base;
 	u32 cxl_version;
 };
 
-static int cxl_get_chbcr(union acpi_subtable_headers *header, void *arg,
+static int cxl_get_chbs(union acpi_subtable_headers *header, void *arg,
 			 const unsigned long end)
 {
 	struct cxl_chbs_context *ctx = arg;
 	struct acpi_cedt_chbs *chbs;
 
-	if (ctx->chbcr)
+	if (ctx->base)
 		return 0;
 
 	chbs = (struct acpi_cedt_chbs *) header;
@@ -395,23 +395,16 @@ static int cxl_get_chbcr(union acpi_subtable_headers *header, void *arg,
 		return 0;
 
 	ctx->cxl_version = chbs->cxl_version;
-	ctx->rcrb = CXL_RESOURCE_NONE;
-	ctx->chbcr = CXL_RESOURCE_NONE;
+	ctx->base = CXL_RESOURCE_NONE;
 
 	if (!chbs->base)
 		return 0;
 
-	if (chbs->cxl_version != ACPI_CEDT_CHBS_VERSION_CXL11) {
-		ctx->chbcr = chbs->base;
-		return 0;
-	}
-
-	if (chbs->length != CXL_RCRB_SIZE)
+	if (chbs->cxl_version == ACPI_CEDT_CHBS_VERSION_CXL11 &&
+	    chbs->length != CXL_RCRB_SIZE)
 		return 0;
 
-	ctx->rcrb = chbs->base;
-	ctx->chbcr = cxl_rcrb_to_component(ctx->dev, chbs->base,
-					   CXL_RCRB_DOWNSTREAM);
+	ctx->base = chbs->base;
 
 	return 0;
 }
@@ -443,33 +436,31 @@ static int add_host_bridge_dport(struct device *match, void *arg)
 		.dev = match,
 		.uid = uid,
 	};
-	acpi_table_parse_cedt(ACPI_CEDT_TYPE_CHBS, cxl_get_chbcr, &ctx);
+	acpi_table_parse_cedt(ACPI_CEDT_TYPE_CHBS, cxl_get_chbs, &ctx);
 
-	if (!ctx.chbcr) {
+	if (!ctx.base) {
 		dev_warn(match, "No CHBS found for Host Bridge (UID %lld)\n",
 			 uid);
 		return 0;
 	}
 
-	if (ctx.rcrb != CXL_RESOURCE_NONE)
-		dev_dbg(match, "RCRB found for UID %lld: %pa\n", uid, &ctx.rcrb);
-
-	if (ctx.chbcr == CXL_RESOURCE_NONE) {
-		dev_warn(match, "CHBCR invalid for Host Bridge (UID %lld)\n",
+	if (ctx.base == CXL_RESOURCE_NONE) {
+		dev_warn(match, "CHBS invalid for Host Bridge (UID %lld)\n",
 			 uid);
 		return 0;
 	}
 
-	dev_dbg(match, "CHBCR found: %pa\n", &ctx.chbcr);
-
 	pci_root = acpi_pci_find_root(hb->handle);
 	bridge = pci_root->bus->bridge;
-	if (ctx.cxl_version == ACPI_CEDT_CHBS_VERSION_CXL11)
-		dport = devm_cxl_add_rch_dport(root_port, bridge, uid,
-					       ctx.chbcr, ctx.rcrb);
-	else
-		dport = devm_cxl_add_dport(root_port, bridge, uid,
-					   ctx.chbcr);
+
+	if (ctx.cxl_version == ACPI_CEDT_CHBS_VERSION_CXL11) {
+		dev_dbg(match, "RCRB found for UID %lld: %pa\n", uid, &ctx.base);
+		dport = devm_cxl_add_rch_dport(root_port, bridge, uid, ctx.base);
+	} else {
+		dev_dbg(match, "CHBCR found for UID %lld: %pa\n", uid, &ctx.base);
+		dport = devm_cxl_add_dport(root_port, bridge, uid, ctx.base);
+	}
+
 	if (IS_ERR(dport))
 		return PTR_ERR(dport);
 
diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 27f0968449de..bd0a5788c696 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -63,6 +63,14 @@ int cxl_dpa_alloc(struct cxl_endpoint_decoder *cxled, unsigned long long size);
 int cxl_dpa_free(struct cxl_endpoint_decoder *cxled);
 resource_size_t cxl_dpa_size(struct cxl_endpoint_decoder *cxled);
 resource_size_t cxl_dpa_resource_start(struct cxl_endpoint_decoder *cxled);
+
+enum cxl_rcrb {
+	CXL_RCRB_DOWNSTREAM,
+	CXL_RCRB_UPSTREAM,
+};
+resource_size_t __rcrb_to_component(struct device *dev, resource_size_t rcrb,
+				    enum cxl_rcrb which);
+
 extern struct rw_semaphore cxl_dpa_rwsem;
 
 int cxl_memdev_init(void);
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index e7c284c890bc..45f5299af7a6 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -938,12 +938,25 @@ __devm_cxl_add_dport(struct cxl_port *port, struct device *dport_dev,
 	if (!dport)
 		return ERR_PTR(-ENOMEM);
 
+	if (rcrb != CXL_RESOURCE_NONE) {
+		component_reg_phys = __rcrb_to_component(dport_dev, rcrb,
+							 CXL_RCRB_DOWNSTREAM);
+		if (component_reg_phys == CXL_RESOURCE_NONE) {
+			dev_warn(dport_dev, "Invalid Component Registers in RCRB");
+			return ERR_PTR(-ENXIO);
+		}
+
+		dport->rch = true;
+	}
+
+	if (component_reg_phys != CXL_RESOURCE_NONE)
+		dev_dbg(dport_dev, "Component Registers found for dport: %pa\n",
+			&component_reg_phys);
+
 	dport->dport = dport_dev;
 	dport->port_id = port_id;
 	dport->component_reg_phys = component_reg_phys;
 	dport->port = port;
-	if (rcrb != CXL_RESOURCE_NONE)
-		dport->rch = true;
 	dport->rcrb = rcrb;
 
 	cond_cxl_root_lock(port);
@@ -1004,14 +1017,12 @@ EXPORT_SYMBOL_NS_GPL(devm_cxl_add_dport, CXL);
  * @port: the cxl_port that references this dport
  * @dport_dev: firmware or PCI device representing the dport
  * @port_id: identifier for this dport in a decoder's target list
- * @component_reg_phys: optional location of CXL component registers
  * @rcrb: mandatory location of a Root Complex Register Block
  *
  * See CXL 3.0 9.11.8 CXL Devices Attached to an RCH
  */
 struct cxl_dport *devm_cxl_add_rch_dport(struct cxl_port *port,
 					 struct device *dport_dev, int port_id,
-					 resource_size_t component_reg_phys,
 					 resource_size_t rcrb)
 {
 	struct cxl_dport *dport;
@@ -1022,7 +1033,7 @@ struct cxl_dport *devm_cxl_add_rch_dport(struct cxl_port *port,
 	}
 
 	dport = __devm_cxl_add_dport(port, dport_dev, port_id,
-				     component_reg_phys, rcrb);
+				     CXL_RESOURCE_NONE, rcrb);
 	if (IS_ERR(dport)) {
 		dev_dbg(dport_dev, "failed to add RCH dport to %s: %ld\n",
 			dev_name(&port->dev), PTR_ERR(dport));
diff --git a/drivers/cxl/core/regs.c b/drivers/cxl/core/regs.c
index 1476a0299c9b..564dd430258a 100644
--- a/drivers/cxl/core/regs.c
+++ b/drivers/cxl/core/regs.c
@@ -332,9 +332,8 @@ int cxl_find_regblock(struct pci_dev *pdev, enum cxl_regloc_type type,
 }
 EXPORT_SYMBOL_NS_GPL(cxl_find_regblock, CXL);
 
-resource_size_t cxl_rcrb_to_component(struct device *dev,
-				      resource_size_t rcrb,
-				      enum cxl_rcrb which)
+resource_size_t __rcrb_to_component(struct device *dev, resource_size_t rcrb,
+				    enum cxl_rcrb which)
 {
 	resource_size_t component_reg_phys;
 	void __iomem *addr;
@@ -395,4 +394,12 @@ resource_size_t cxl_rcrb_to_component(struct device *dev,
 
 	return component_reg_phys;
 }
-EXPORT_SYMBOL_NS_GPL(cxl_rcrb_to_component, CXL);
+
+resource_size_t cxl_rcd_component_reg_phys(struct device *dev,
+					   struct cxl_dport *dport)
+{
+	if (!dport->rch)
+		return CXL_RESOURCE_NONE;
+	return __rcrb_to_component(dev, dport->rcrb, CXL_RCRB_UPSTREAM);
+}
+EXPORT_SYMBOL_NS_GPL(cxl_rcd_component_reg_phys, CXL);
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index f93a28538962..28888bb0c088 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -262,14 +262,9 @@ int cxl_map_device_regs(struct device *dev, struct cxl_device_regs *regs,
 enum cxl_regloc_type;
 int cxl_find_regblock(struct pci_dev *pdev, enum cxl_regloc_type type,
 		      struct cxl_register_map *map);
-
-enum cxl_rcrb {
-	CXL_RCRB_DOWNSTREAM,
-	CXL_RCRB_UPSTREAM,
-};
-resource_size_t cxl_rcrb_to_component(struct device *dev,
-				      resource_size_t rcrb,
-				      enum cxl_rcrb which);
+struct cxl_dport;
+resource_size_t cxl_rcd_component_reg_phys(struct device *dev,
+					   struct cxl_dport *dport);
 
 #define CXL_RESOURCE_NONE ((resource_size_t) -1)
 #define CXL_TARGET_STRLEN 20
@@ -671,7 +666,6 @@ struct cxl_dport *devm_cxl_add_dport(struct cxl_port *port,
 				     resource_size_t component_reg_phys);
 struct cxl_dport *devm_cxl_add_rch_dport(struct cxl_port *port,
 					 struct device *dport_dev, int port_id,
-					 resource_size_t component_reg_phys,
 					 resource_size_t rcrb);
 
 struct cxl_decoder *to_cxl_decoder(struct device *dev);
diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index 519edd0eb196..45d4c32d78b0 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -72,8 +72,8 @@ static int devm_cxl_add_endpoint(struct device *host, struct cxl_memdev *cxlmd,
 	 * typical register locator mechanism.
 	 */
 	if (parent_dport->rch && cxlds->component_reg_phys == CXL_RESOURCE_NONE)
-		component_reg_phys = cxl_rcrb_to_component(
-			&cxlmd->dev, parent_dport->rcrb, CXL_RCRB_UPSTREAM);
+		component_reg_phys =
+			cxl_rcd_component_reg_phys(&cxlmd->dev, parent_dport);
 	else
 		component_reg_phys = cxlds->component_reg_phys;
 	endpoint = devm_cxl_add_port(host, &cxlmd->dev, component_reg_phys,