[PATCH v3 4/5] fpga: dfl: Handle dfl's starting with AFU

[Tianfei zhang <tianfei.zhang@xxxxxxxxx>]

From: Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>

Allow for a Device Feature List (DFL) to start with
a Device Feature Header (DFH) of type Accelerator Function Unit (AFU)
by doing nothing. This allows for PCIe VFs to be created.

Signed-off-by: Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>
Signed-off-by: Tianfei Zhang <tianfei.zhang@xxxxxxxxx>
---
 drivers/fpga/dfl-pci.c |  7 ++++++-
 drivers/fpga/dfl.c     | 22 +++++++++++++---------
 2 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/drivers/fpga/dfl-pci.c b/drivers/fpga/dfl-pci.c
index 33545c999c06..e7d58e7b1bbd 100644
--- a/drivers/fpga/dfl-pci.c
+++ b/drivers/fpga/dfl-pci.c
@@ -275,7 +275,12 @@ static int find_dfls_by_default(struct pci_dev *pcidev,
 
 		dfl_fpga_enum_info_add_dfl(info, start, len);
 	} else {
-		ret = -ENODEV;
+		v = readq(base + DFH);
+		if (FIELD_GET(DFH_TYPE, v) != DFH_TYPE_AFU) {
+			dev_info(&pcidev->dev, "Unknown feature type 0x%llx id 0x%llx\n",
+				 FIELD_GET(DFH_TYPE, v), FIELD_GET(DFH_ID, v));
+			ret = -ENODEV;
+		}
 	}
 
 	/* release I/O mappings for next step enumeration */
diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
index fd04ef5c8b03..e30bbb3039cd 100644
--- a/drivers/fpga/dfl.c
+++ b/drivers/fpga/dfl.c
@@ -900,9 +900,11 @@ static void build_info_free(struct build_feature_devs_info *binfo)
 		dfl_id_free(feature_dev_id_type(binfo->feature_dev),
 			    binfo->feature_dev->id);
 
-		list_for_each_entry_safe(finfo, p, &binfo->sub_features, node) {
-			list_del(&finfo->node);
-			kfree(finfo);
+		if (!list_empty(&binfo->sub_features)) {
+			list_for_each_entry_safe(finfo, p, &binfo->sub_features, node) {
+				list_del(&finfo->node);
+				kfree(finfo);
+			}
 		}
 	}
 
@@ -1439,12 +1441,14 @@ dfl_fpga_feature_devs_enumerate(struct dfl_fpga_enum_info *info)
 	 * start enumeration for all feature devices based on Device Feature
 	 * Lists.
 	 */
-	list_for_each_entry(dfl, &info->dfls, node) {
-		ret = parse_feature_list(binfo, dfl->start, dfl->len);
-		if (ret) {
-			remove_feature_devs(cdev);
-			build_info_free(binfo);
-			goto unregister_region_exit;
+	if (!list_empty(&info->dfls)) {
+		list_for_each_entry(dfl, &info->dfls, node) {
+			ret = parse_feature_list(binfo, dfl->start, dfl->len);
+			if (ret) {
+				remove_feature_devs(cdev);
+				build_info_free(binfo);
+				goto unregister_region_exit;
+			}
 		}
 	}
 
-- 
2.26.2