cxl/region: Move region-position validation to a helper

In preparation for region autodiscovery, that needs all devices
discovered before their relative position in the region can be
determined, consolidate all position dependent validation in a helper.

Recall that in the on-demand region creation flow the end-user picks the
position of a given endpoint decoder in a region. In the autodiscovery
case the position of an endpoint decoder can only be determined after
all other endpoint decoders that claim to decode the region's address
range have been enumerated and attached. So, in the autodiscovery case
endpoint decoders may be attached before their relative position is
known. Once all decoders arrive, then positions can be determined and
validated with cxl_region_validate_position() the same as user initiated
on-demand creation.

Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
Tested-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/167601997584.1924368.4615769326126138969.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/cxl/core/region.c

@@ -1211,35 +1211,13 @@ static int cxl_region_setup_targets(struct cxl_region *cxlr)
 	return 0;
 }
 
-static int cxl_region_attach(struct cxl_region *cxlr,
-			     struct cxl_endpoint_decoder *cxled, int pos)
+static int cxl_region_validate_position(struct cxl_region *cxlr,
+					struct cxl_endpoint_decoder *cxled,
+					int pos)
 {
-	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(cxlr->dev.parent);
 	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
-	struct cxl_port *ep_port, *root_port, *iter;
 	struct cxl_region_params *p = &cxlr->params;
-	struct cxl_dport *dport;
-	int i, rc = -ENXIO;
-
-	if (cxled->mode != cxlr->mode) {
-		dev_dbg(&cxlr->dev, "%s region mode: %d mismatch: %d\n",
-			dev_name(&cxled->cxld.dev), cxlr->mode, cxled->mode);
-		return -EINVAL;
-	}
-
-	if (cxled->mode == CXL_DECODER_DEAD) {
-		dev_dbg(&cxlr->dev, "%s dead\n", dev_name(&cxled->cxld.dev));
-		return -ENODEV;
-	}
-
-	/* all full of members, or interleave config not established? */
-	if (p->state > CXL_CONFIG_INTERLEAVE_ACTIVE) {
-		dev_dbg(&cxlr->dev, "region already active\n");
-		return -EBUSY;
-	} else if (p->state < CXL_CONFIG_INTERLEAVE_ACTIVE) {
-		dev_dbg(&cxlr->dev, "interleave config missing\n");
-		return -ENXIO;
-	}
+	int i;
 
 	if (pos < 0 || pos >= p->interleave_ways) {
 		dev_dbg(&cxlr->dev, "position %d out of range %d\n", pos,
@@ -1278,6 +1256,71 @@ static int cxl_region_attach(struct cxl_region *cxlr,
 		}
 	}
 
+	return 0;
+}
+
+static int cxl_region_attach_position(struct cxl_region *cxlr,
+				      struct cxl_root_decoder *cxlrd,
+				      struct cxl_endpoint_decoder *cxled,
+				      const struct cxl_dport *dport, int pos)
+{
+	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
+	struct cxl_port *iter;
+	int rc;
+
+	if (cxlrd->calc_hb(cxlrd, pos) != dport) {
+		dev_dbg(&cxlr->dev, "%s:%s invalid target position for %s\n",
+			dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev),
+			dev_name(&cxlrd->cxlsd.cxld.dev));
+		return -ENXIO;
+	}
+
+	for (iter = cxled_to_port(cxled); !is_cxl_root(iter);
+	     iter = to_cxl_port(iter->dev.parent)) {
+		rc = cxl_port_attach_region(iter, cxlr, cxled, pos);
+		if (rc)
+			goto err;
+	}
+
+	return 0;
+
+err:
+	for (iter = cxled_to_port(cxled); !is_cxl_root(iter);
+	     iter = to_cxl_port(iter->dev.parent))
+		cxl_port_detach_region(iter, cxlr, cxled);
+	return rc;
+}
+
+static int cxl_region_attach(struct cxl_region *cxlr,
+			     struct cxl_endpoint_decoder *cxled, int pos)
+{
+	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(cxlr->dev.parent);
+	struct cxl_memdev *cxlmd = cxled_to_memdev(cxled);
+	struct cxl_region_params *p = &cxlr->params;
+	struct cxl_port *ep_port, *root_port;
+	struct cxl_dport *dport;
+	int rc = -ENXIO;
+
+	if (cxled->mode != cxlr->mode) {
+		dev_dbg(&cxlr->dev, "%s region mode: %d mismatch: %d\n",
+			dev_name(&cxled->cxld.dev), cxlr->mode, cxled->mode);
+		return -EINVAL;
+	}
+
+	if (cxled->mode == CXL_DECODER_DEAD) {
+		dev_dbg(&cxlr->dev, "%s dead\n", dev_name(&cxled->cxld.dev));
+		return -ENODEV;
+	}
+
+	/* all full of members, or interleave config not established? */
+	if (p->state > CXL_CONFIG_INTERLEAVE_ACTIVE) {
+		dev_dbg(&cxlr->dev, "region already active\n");
+		return -EBUSY;
+	} else if (p->state < CXL_CONFIG_INTERLEAVE_ACTIVE) {
+		dev_dbg(&cxlr->dev, "interleave config missing\n");
+		return -ENXIO;
+	}
+
 	ep_port = cxled_to_port(cxled);
 	root_port = cxlrd_to_port(cxlrd);
 	dport = cxl_find_dport_by_dev(root_port, ep_port->host_bridge);
@@ -1288,13 +1331,6 @@ static int cxl_region_attach(struct cxl_region *cxlr,
 		return -ENXIO;
 	}
 
-	if (cxlrd->calc_hb(cxlrd, pos) != dport) {
-		dev_dbg(&cxlr->dev, "%s:%s invalid target position for %s\n",
-			dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev),
-			dev_name(&cxlrd->cxlsd.cxld.dev));
-		return -ENXIO;
-	}
-
 	if (cxled->cxld.target_type != cxlr->type) {
 		dev_dbg(&cxlr->dev, "%s:%s type mismatch: %d vs %d\n",
 			dev_name(&cxlmd->dev), dev_name(&cxled->cxld.dev),
@@ -1318,12 +1354,13 @@ static int cxl_region_attach(struct cxl_region *cxlr,
 		return -EINVAL;
 	}
 
-	for (iter = ep_port; !is_cxl_root(iter);
-	     iter = to_cxl_port(iter->dev.parent)) {
-		rc = cxl_port_attach_region(iter, cxlr, cxled, pos);
-		if (rc)
-			goto err;
-	}
+	rc = cxl_region_validate_position(cxlr, cxled, pos);
+	if (rc)
+		return rc;
+
+	rc = cxl_region_attach_position(cxlr, cxlrd, cxled, dport, pos);
+	if (rc)
+		return rc;
 
 	p->targets[pos] = cxled;
 	cxled->pos = pos;
@@ -1349,10 +1386,6 @@ static int cxl_region_attach(struct cxl_region *cxlr,
 	p->nr_targets--;
 	cxled->pos = -1;
 	p->targets[pos] = NULL;
-err:
-	for (iter = ep_port; !is_cxl_root(iter);
-	     iter = to_cxl_port(iter->dev.parent))
-		cxl_port_detach_region(iter, cxlr, cxled);
 	return rc;
 }