[PATCH v6 8/9] cxl/pci: Split BI capability probe from setup

[Davidlohr Bueso <dave@stgolabs.net>]

Decouple the topology read-only capability verification phase from
cxl_bi_setup() into cxl_bi_probe_capable(), recording the result in
cxlds->bi_capable.

This allows further dealing with auto-committed BI hdm decoders;
having such knowledge upon decoder enumeration time.

No functional change intended.

Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
---
 drivers/cxl/core/pci.c | 39 ++++++++++++++++++++++++++++-----------
 drivers/cxl/cxl.h      |  1 +
 drivers/cxl/port.c     |  1 +
 include/cxl/cxl.h      |  2 ++
 4 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index a87c2ad9ac53..554058ccb1e9 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -1290,35 +1290,38 @@ static int cxl_bi_enable_path(struct cxl_dev_state *cxlds,
 	return rc;
 }
 
-int cxl_bi_setup(struct cxl_port *endpoint)
+/*
+ * Verify the device and every component in the path up to the root
+ * are BI capable.
+ */
+void cxl_bi_probe_capable(struct cxl_port *endpoint)
 {
 	struct cxl_memdev *cxlmd = to_cxl_memdev(endpoint->uport_dev);
 	struct cxl_dev_state *cxlds = cxlmd->cxlds;
-	struct cxl_dport *dport = endpoint->parent_dport;
 	struct cxl_dport *dport_iter;
 	struct cxl_port *port_iter;
-	int rc;
+
+	cxlds->bi_capable = false;
 
 	if (!dev_is_pci(cxlds->dev))
-		return 0;
+		return;
 
 	/* BI is VH-only */
 	if (cxlds->rcd)
-		return 0;
+		return;
 
 	if (!cxl_is_bi_capable(to_pci_dev(cxlds->dev),
 			       endpoint->regs.bi_decoder))
-		return 0;
+		return;
 
-	/* walkup the topology twice, first to check, then to enable */
-	port_iter = dport->port;
-	dport_iter = dport;
+	dport_iter = endpoint->parent_dport;
+	port_iter = dport_iter->port;
 	while (!is_cxl_root(port_iter)) {
 		/* check rp, dsp */
 		if (!cxl_is_bi_capable(to_pci_dev(dport_iter->dport_dev),
 				       dport_iter->regs.bi_decoder)) {
 			dev_dbg(cxlds->dev, "BI not supported by topology\n");
-			return 0;
+			return;
 		}
 
 		/* check usp */
@@ -1328,13 +1331,27 @@ int cxl_bi_setup(struct cxl_port *endpoint)
 		    !cxl_is_bi_capable(to_pci_dev(port_iter->uport_dev),
 				       port_iter->regs.bi_rt)) {
 			dev_dbg(cxlds->dev, "BI not supported by USP\n");
-			return 0;
+			return;
 		}
 
 		dport_iter = port_iter->parent_dport;
 		port_iter = dport_iter->port;
 	}
 
+	cxlds->bi_capable = true;
+}
+EXPORT_SYMBOL_NS_GPL(cxl_bi_probe_capable, "CXL");
+
+int cxl_bi_setup(struct cxl_port *endpoint)
+{
+	struct cxl_memdev *cxlmd = to_cxl_memdev(endpoint->uport_dev);
+	struct cxl_dev_state *cxlds = cxlmd->cxlds;
+	struct cxl_dport *dport = endpoint->parent_dport;
+	int rc;
+
+	if (!cxlds->bi_capable)
+		return 0;
+
 	rc = cxl_bi_enable_path(cxlds, dport->port, dport);
 	if (rc)
 		return rc;
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index ca7051641c47..e10d642684e1 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -963,6 +963,7 @@ void cxl_coordinates_combine(struct access_coordinate *out,
 			     struct access_coordinate *c2);
 
 bool cxl_endpoint_decoder_reset_detected(struct cxl_port *port);
+void cxl_bi_probe_capable(struct cxl_port *endpoint);
 int cxl_bi_setup(struct cxl_port *endpoint);
 struct cxl_dport *devm_cxl_add_dport_by_dev(struct cxl_port *port,
 					    struct device *dport_dev);
diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c
index 22bd4254ba8d..ab3317fc1388 100644
--- a/drivers/cxl/port.c
+++ b/drivers/cxl/port.c
@@ -170,6 +170,7 @@ static int cxl_endpoint_port_probe(struct cxl_port *port)
 	cxl_endpoint_parse_cdat(port);
 
 	cxl_port_map_bi(port);
+	cxl_bi_probe_capable(port);
 
 	get_device(&cxlmd->dev);
 	rc = devm_add_action_or_reset(&port->dev, schedule_detach, cxlmd);
diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
index e507cb0f777f..80d942eb9456 100644
--- a/include/cxl/cxl.h
+++ b/include/cxl/cxl.h
@@ -169,6 +169,7 @@ struct cxl_dpa_partition {
  * @cxl_dvsec: Offset to the PCIe device DVSEC
  * @rcd: operating in RCD mode (CXL 3.0 9.11.8 CXL Devices Attached to an RCH)
  * @bi: device is BI (Back-Invalidate) enabled
+ * @bi_capable: device and topology path are BI capable
  * @media_ready: Indicate whether the device media is usable
  * @dpa_res: Overall DPA resource tree for the device
  * @part: DPA partition array
@@ -189,6 +190,7 @@ struct cxl_dev_state {
 	int cxl_dvsec;
 	bool rcd;
 	bool bi;
+	bool bi_capable;
 	bool media_ready;
 	struct resource dpa_res;
 	struct cxl_dpa_partition part[CXL_NR_PARTITIONS_MAX];
-- 
2.39.5