cxl: Store the access coordinates for the generic ports

Each CXL host bridge is represented by an ACPI0016 device. A generic port
device handle that is an ACPI device is represented by a string of
ACPI0016 device HID and UID. Create a device handle from the ACPI device
and retrieve the access coordinates from the stored memory targets. The
access coordinates are stored under the cxl_dport that is associated with
the CXL host bridge.

The access coordinates struct is dynamically allocated under cxl_dport in
order for code later on to detect whether the data exists or not.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/170319623196.2212653.17916695743464172534.stgit@djiang5-mobl3Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/cxl/acpi.c

@@ -513,8 +513,29 @@ static int cxl_get_chbs(struct device *dev, struct acpi_device *hb,
 	return 0;
 }
 
+static int get_genport_coordinates(struct device *dev, struct cxl_dport *dport)
+{
+	struct acpi_device *hb = to_cxl_host_bridge(NULL, dev);
+	u32 uid;
+	int rc;
+
+	if (kstrtou32(acpi_device_uid(hb), 0, &uid))
+		return -EINVAL;
+
+	rc = acpi_get_genport_coordinates(uid, &dport->hb_coord);
+	if (rc < 0)
+		return rc;
+
+	/* Adjust back to picoseconds from nanoseconds */
+	dport->hb_coord.read_latency *= 1000;
+	dport->hb_coord.write_latency *= 1000;
+
+	return 0;
+}
+
 static int add_host_bridge_dport(struct device *match, void *arg)
 {
+	int ret;
 	acpi_status rc;
 	struct device *bridge;
 	struct cxl_dport *dport;
@@ -564,6 +585,10 @@ static int add_host_bridge_dport(struct device *match, void *arg)
 	if (IS_ERR(dport))
 		return PTR_ERR(dport);
 
+	ret = get_genport_coordinates(match, dport);
+	if (ret)
+		dev_dbg(match, "Failed to get generic port perf coordinates.\n");
+
 	return 0;
 }
 

drivers/cxl/cxl.h

@@ -661,6 +661,7 @@ struct cxl_rcrb_info {
  * @port: reference to cxl_port that contains this downstream port
  * @regs: Dport parsed register blocks
  * @sw_coord: access coordinates (performance) for switch from CDAT
+ * @hb_coord: access coordinates (performance) from ACPI generic port (host bridge)
  * @link_latency: calculated PCIe downstream latency
  */
 struct cxl_dport {
@@ -672,6 +673,7 @@ struct cxl_dport {
 	struct cxl_port *port;
 	struct cxl_regs regs;
 	struct access_coordinate sw_coord;
+	struct access_coordinate hb_coord;
 	long link_latency;
 };