[PATCH v15 02/16] cxl: Share CXL port upstream PCI device lookup

[Srirangan Madhavan <smadhavan@nvidia.com>]

read_cdat_data() resolves a CXL port's upstream device to its backing PCI
device. HDM cache updates need the same mapping.

Factor the lookup into cxl_port_get_uport_pci_dev() and return a referenced
PCI device to make caller ownership explicit.

Use automatic reference cleanup in read_cdat_data(), as suggested by
Li Ming, so early returns release the PCI device reference.

Signed-off-by: Srirangan Madhavan <smadhavan@nvidia.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Richard Cheng <icheng@nvidia.com>
Reviewed-by: Li Ming <ming.li@zohomail.com>
---
 drivers/cxl/core/core.h |  1 +
 drivers/cxl/core/pci.c  | 16 ++--------------
 drivers/cxl/core/port.c | 26 ++++++++++++++++++++++++++
 3 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 35eaf636adc9..983d7690c3a5 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -157,6 +157,7 @@ long cxl_pci_get_latency(struct pci_dev *pdev);
 int cxl_pci_get_bandwidth(struct pci_dev *pdev, struct access_coordinate *c);
 int cxl_port_get_switch_dport_bandwidth(struct cxl_port *port,
 					struct access_coordinate *c);
+struct pci_dev *cxl_port_get_uport_pci_dev(struct cxl_port *port);
 
 static inline struct device *port_to_host(struct cxl_port *port)
 {
diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index 9d807c1a002c..c3c41efae5fd 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -564,26 +564,14 @@ static unsigned char cdat_checksum(void *buf, size_t size)
  */
 void read_cdat_data(struct cxl_port *port)
 {
-	struct device *uport = port->uport_dev;
+	struct pci_dev *pdev __free(pci_dev_put) =
+		cxl_port_get_uport_pci_dev(port);
 	struct device *dev = &port->dev;
 	struct pci_doe_mb *doe_mb;
-	struct pci_dev *pdev = NULL;
-	struct cxl_memdev *cxlmd;
 	struct cdat_doe_rsp *buf;
 	size_t table_length, length;
 	int rc;
 
-	if (is_cxl_memdev(uport)) {
-		struct device *host;
-
-		cxlmd = to_cxl_memdev(uport);
-		host = cxlmd->dev.parent;
-		if (dev_is_pci(host))
-			pdev = to_pci_dev(host);
-	} else if (dev_is_pci(uport)) {
-		pdev = to_pci_dev(uport);
-	}
-
 	if (!pdev)
 		return;
 
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 625e4aa427db..5dc2815d82d8 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -34,6 +34,32 @@
 static DEFINE_IDA(cxl_port_ida);
 static DEFINE_XARRAY(cxl_root_buses);
 
+/**
+ * cxl_port_get_uport_pci_dev - get the PCI device for a port's upstream device
+ * @port: CXL port to map to a PCI device
+ *
+ * Return: A referenced PCI device, or NULL if the upstream device is not PCI.
+ * The caller must release the returned reference with pci_dev_put().
+ */
+struct pci_dev *cxl_port_get_uport_pci_dev(struct cxl_port *port)
+{
+	struct device *uport = port->uport_dev;
+	struct device *host;
+
+	if (is_cxl_memdev(uport)) {
+		struct cxl_memdev *cxlmd = to_cxl_memdev(uport);
+
+		host = cxlmd->dev.parent;
+	} else {
+		host = uport;
+	}
+
+	if (!host || !dev_is_pci(host))
+		return NULL;
+
+	return pci_dev_get(to_pci_dev(host));
+}
+
 /*
  * The terminal device in PCI is NULL and @platform_bus
  * for platform devices (for cxl_test)
-- 
2.43.0