fpga: region: separate out code that parses the overlay

New function of_fpga_region_parse_ov added, moving code
from fpga_region_notify_pre_apply.  This function
gets the FPGA image info from the overlay and is able
to simplify some of the logic involved.

This is a baby step in refactoring the FPGA region code to
separate out common code from Device Tree overlay support.
Signed-off-by: Alan Tull <atull@kernel.org>
Acked-by: Moritz Fischer <mdf@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/fpga/fpga-region.c

@@ -321,33 +321,22 @@ static int child_regions_with_firmware(struct device_node *overlay)
 }
 
 /**
- * fpga_region_notify_pre_apply - pre-apply overlay notification
- *
- * @region: FPGA region that the overlay was applied to
- * @nd: overlay notification data
- *
- * Called after when an overlay targeted to a FPGA Region is about to be
- * applied.  Function will check the properties that will be added to the FPGA
- * region.  If the checks pass, it will program the FPGA.
- *
- * The checks are:
- * The overlay must add either firmware-name or external-fpga-config property
- * to the FPGA Region.
- *
- *   firmware-name         : program the FPGA
- *   external-fpga-config  : FPGA is already programmed
- *   encrypted-fpga-config : FPGA bitstream is encrypted
+ * of_fpga_region_parse_ov - parse and check overlay applied to region
  *
- * The overlay can add other FPGA regions, but child FPGA regions cannot have a
- * firmware-name property since those regions don't exist yet.
+ * @region: FPGA region
+ * @overlay: overlay applied to the FPGA region
  *
- * If the overlay that breaks the rules, notifier returns an error and the
- * overlay is rejected before it goes into the main tree.
+ * Given an overlay applied to a FPGA region, parse the FPGA image specific
+ * info in the overlay and do some checking.
  *
- * Returns 0 for success or negative error code for failure.
+ * Returns:
+ *   NULL if overlay doesn't direct us to program the FPGA.
+ *   fpga_image_info struct if there is an image to program.
+ *   error code for invalid overlay.
  */
-static int fpga_region_notify_pre_apply(struct fpga_region *region,
-					struct of_overlay_notify_data *nd)
+static struct fpga_image_info *of_fpga_region_parse_ov(
+						struct fpga_region *region,
+						struct device_node *overlay)
 {
 	struct device *dev = &region->dev;
 	struct fpga_image_info *info;
@@ -356,7 +345,7 @@ static int fpga_region_notify_pre_apply(struct fpga_region *region,
 
 	if (region->info) {
 		dev_err(dev, "Region already has overlay applied.\n");
-		return -EINVAL;
+		return ERR_PTR(-EINVAL);
 	}
 
 	/*
@@ -364,67 +353,102 @@ static int fpga_region_notify_pre_apply(struct fpga_region *region,
 	 * firmware-name property (would mean that an FPGA region that has
 	 * not been added to the live tree yet is doing FPGA programming).
 	 */
-	ret = child_regions_with_firmware(nd->overlay);
+	ret = child_regions_with_firmware(overlay);
 	if (ret)
-		return ret;
+		return ERR_PTR(ret);
 
 	info = fpga_image_info_alloc(dev);
 	if (!info)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
-	info->overlay = nd->overlay;
+	info->overlay = overlay;
 
 	/* Read FPGA region properties from the overlay */
-	if (of_property_read_bool(nd->overlay, "partial-fpga-config"))
+	if (of_property_read_bool(overlay, "partial-fpga-config"))
 		info->flags |= FPGA_MGR_PARTIAL_RECONFIG;
 
-	if (of_property_read_bool(nd->overlay, "external-fpga-config"))
+	if (of_property_read_bool(overlay, "external-fpga-config"))
 		info->flags |= FPGA_MGR_EXTERNAL_CONFIG;
 
-	if (of_property_read_bool(nd->overlay, "encrypted-fpga-config"))
+	if (of_property_read_bool(overlay, "encrypted-fpga-config"))
 		info->flags |= FPGA_MGR_ENCRYPTED_BITSTREAM;
 
-	if (!of_property_read_string(nd->overlay, "firmware-name",
+	if (!of_property_read_string(overlay, "firmware-name",
 				     &firmware_name)) {
 		info->firmware_name = devm_kstrdup(dev, firmware_name,
 						   GFP_KERNEL);
 		if (!info->firmware_name)
-			return -ENOMEM;
+			return ERR_PTR(-ENOMEM);
 	}
 
-	of_property_read_u32(nd->overlay, "region-unfreeze-timeout-us",
+	of_property_read_u32(overlay, "region-unfreeze-timeout-us",
 			     &info->enable_timeout_us);
 
-	of_property_read_u32(nd->overlay, "region-freeze-timeout-us",
+	of_property_read_u32(overlay, "region-freeze-timeout-us",
 			     &info->disable_timeout_us);
 
-	of_property_read_u32(nd->overlay, "config-complete-timeout-us",
+	of_property_read_u32(overlay, "config-complete-timeout-us",
 			     &info->config_complete_timeout_us);
 
-	/* If FPGA was externally programmed, don't specify firmware */
-	if ((info->flags & FPGA_MGR_EXTERNAL_CONFIG) && info->firmware_name) {
-		dev_err(dev, "error: specified firmware and external-fpga-config");
-		fpga_image_info_free(info);
-		return -EINVAL;
+	/* If overlay is not programming the FPGA, don't need FPGA image info */
+	if (!info->firmware_name) {
+		ret = 0;
+		goto ret_no_info;
 	}
 
-	/* FPGA is already configured externally.  We're done. */
+	/*
+	 * If overlay informs us FPGA was externally programmed, specifying
+	 * firmware here would be ambiguous.
+	 */
 	if (info->flags & FPGA_MGR_EXTERNAL_CONFIG) {
-		fpga_image_info_free(info);
-		return 0;
+		dev_err(dev, "error: specified firmware and external-fpga-config");
+		ret = -EINVAL;
+		goto ret_no_info;
 	}
 
-	/* If we got this far, we should be programming the FPGA */
-	if (!info->firmware_name) {
-		dev_err(dev, "should specify firmware-name or external-fpga-config\n");
-		fpga_image_info_free(info);
+	return info;
+ret_no_info:
+	fpga_image_info_free(info);
+	return ERR_PTR(ret);
+}
+
+/**
+ * fpga_region_notify_pre_apply - pre-apply overlay notification
+ *
+ * @region: FPGA region that the overlay was applied to
+ * @nd: overlay notification data
+ *
+ * Called when an overlay targeted to a FPGA Region is about to be applied.
+ * Parses the overlay for properties that influence how the FPGA will be
+ * programmed and does some checking. If the checks pass, programs the FPGA.
+ * If the checks fail, overlay is rejected and does not get added to the
+ * live tree.
+ *
+ * Returns 0 for success or negative error code for failure.
+ */
+static int fpga_region_notify_pre_apply(struct fpga_region *region,
+					struct of_overlay_notify_data *nd)
+{
+	struct device *dev = &region->dev;
+	struct fpga_image_info *info;
+	int ret;
+
+	if (region->info) {
+		dev_err(dev, "Region already has overlay applied.\n");
 		return -EINVAL;
 	}
 
-	region->info = info;
+	info = of_fpga_region_parse_ov(region, nd->overlay);
+	if (IS_ERR(info))
+		return PTR_ERR(info);
+
+	if (!info)
+		return 0;
 
+	region->info = info;
 	ret = fpga_region_program_fpga(region);
 	if (ret) {
+		/* error; reject overlay */
 		fpga_image_info_free(info);
 		region->info = NULL;
 	}