Merge patch series "Convert extension support to UCLASS and adds its support to boot flows"

Kory Maincent (TI.com) <kory.maincent@bootlin.com> says:

This series converts the extension board framework to use UCLASS as
requested by Simon Glass, then adds extension support to pxe_utils
and bootmeth_efi (not tested) to enable extension boards devicetree load
in the standard boot process.

I can't test the imx8 extension scan enabled by the
imx8mm-cl-iot-gate_defconfig as I don't have this board.
I also can't test the efi bootmeth change as I don't have such board.

Link: https://lore.kernel.org/r/20251030-feature_sysboot_extension_board-v5-0-cfb77672fc68@bootlin.com

boot/Kconfig

@@ -1909,6 +1909,10 @@ endmenu
 
 endif # OF_LIBFDT
 
+config SUPPORT_EXTENSION_SCAN
+	select OF_LIBFDT_OVERLAY
+        bool
+
 config USE_BOOTARGS
 	bool "Enable boot arguments"
 	help

boot/Makefile

@@ -9,6 +9,7 @@ obj-$(CONFIG_BOOT_RETRY) += bootretry.o
 obj-$(CONFIG_CMD_BOOTM) += bootm.o bootm_os.o
 obj-$(CONFIG_CMD_BOOTZ) += bootm.o bootm_os.o
 obj-$(CONFIG_CMD_BOOTI) += bootm.o bootm_os.o
+obj-$(CONFIG_SUPPORT_EXTENSION_SCAN) += extension-uclass.o
 
 obj-$(CONFIG_PXE_UTILS) += pxe_utils.o
 

boot/bootmeth_efi.c

@@ -16,6 +16,7 @@
 #include <efi.h>
 #include <efi_loader.h>
 #include <env.h>
+#include <extension_board.h>
 #include <fs.h>
 #include <malloc.h>
 #include <mapmem.h>
@@ -99,8 +100,11 @@ static int distro_efi_check(struct udevice *dev, struct bootflow_iter *iter)
 static int distro_efi_try_bootflow_files(struct udevice *dev,
 					 struct bootflow *bflow)
 {
+	ulong fdt_addr, size, overlay_addr;
+	const struct extension *extension;
+	struct fdt_header *working_fdt;
 	struct blk_desc *desc = NULL;
-	ulong fdt_addr, size;
+	struct alist *extension_list;
 	char fname[256];
 	int ret, seq;
 
@@ -148,23 +152,66 @@ static int distro_efi_try_bootflow_files(struct udevice *dev,
 			return log_msg_ret("fil", -ENOMEM);
 	}
 
-	if (!ret) {
-		bflow->fdt_size = size;
-		bflow->fdt_addr = fdt_addr;
-
-		/*
-		 * TODO: Apply extension overlay
-		 *
-		 * Here we need to load and apply the extension overlay. This is
-		 * not implemented. See do_extension_apply(). The extension
-		 * stuff needs an implementation in boot/extension.c so it is
-		 * separate from the command code. Really the extension stuff
-		 * should use the device tree and a uclass / driver interface
-		 * rather than implementing its own list
-		 */
-	} else {
+	if (ret) {
 		log_debug("No device tree available\n");
 		bflow->flags |= BOOTFLOWF_USE_BUILTIN_FDT;
+		return 0;
+	}
+
+	bflow->fdt_size = size;
+	bflow->fdt_addr = fdt_addr;
+
+	if (!CONFIG_IS_ENABLED(SUPPORT_EXTENSION_SCAN))
+		return 0;
+
+	ret = extension_scan();
+	if (ret < 0)
+		return 0;
+
+	extension_list = extension_get_list();
+	if (!extension_list)
+		return 0;
+
+	working_fdt = map_sysmem(fdt_addr, 0);
+	if (fdt_check_header(working_fdt))
+		return 0;
+
+	overlay_addr = env_get_hex("extension_overlay_addr", 0);
+	if (!overlay_addr) {
+		log_debug("Environment extension_overlay_addr is missing\n");
+		return 0;
+	}
+
+	alist_for_each(extension, extension_list) {
+		char *overlay_file;
+		int len;
+
+		len = sizeof(EFI_DIRNAME) + strlen(extension->overlay);
+		overlay_file = calloc(1, len);
+		if (!overlay_file)
+			return -ENOMEM;
+
+		snprintf(overlay_file, len, "%s%s", EFI_DIRNAME,
+			 extension->overlay);
+
+		ret = bootmeth_common_read_file(dev, bflow, overlay_file,
+						overlay_addr,
+						(enum bootflow_img_t)IH_TYPE_FLATDT,
+						&size);
+		if (ret) {
+			log_debug("Failed loading overlay %s\n", overlay_file);
+			free(overlay_file);
+			continue;
+		}
+
+		ret = extension_apply(working_fdt, size);
+		if (ret) {
+			log_debug("Failed applying overlay %s\n", overlay_file);
+			free(overlay_file);
+			continue;
+		}
+		bflow->fdt_size += size;
+		free(overlay_file);
 	}
 
 	return 0;

boot/extension-uclass.c

@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2025 Köry Maincent <kory.maincent@bootlin.com>
+ */
+
+#include <alist.h>
+#include <command.h>
+#include <env.h>
+#include <extension_board.h>
+#include <fdt_support.h>
+#include <malloc.h>
+#include <mapmem.h>
+#include <dm/device-internal.h>
+#include <dm/lists.h>
+#include <dm/uclass.h>
+
+struct alist *extension_get_list(void)
+{
+	struct udevice *dev;
+
+	if (uclass_first_device_err(UCLASS_EXTENSION, &dev))
+		return NULL;
+
+	return dev_get_priv(dev);
+}
+
+int extension_probe(struct udevice *dev)
+{
+	struct alist *extension_list = dev_get_priv(dev);
+
+	alist_init_struct(extension_list, struct extension);
+	return 0;
+}
+
+int extension_remove(struct udevice *dev)
+{
+	struct alist *extension_list = dev_get_priv(dev);
+
+	alist_uninit(extension_list);
+	return 0;
+}
+
+int extension_scan(void)
+{
+	struct alist *extension_list = extension_get_list();
+	const struct extension_ops *ops;
+	struct udevice *dev;
+	int ret;
+
+	ret = uclass_first_device_err(UCLASS_EXTENSION, &dev);
+	if (ret)
+		return ret;
+
+	if (!extension_list)
+		return -ENODEV;
+
+	ops = extension_get_ops(dev);
+	alist_empty(extension_list);
+	return ops->scan(dev, extension_list);
+}
+
+int extension_apply(struct fdt_header *working_fdt, ulong size)
+{
+	struct fdt_header *blob;
+	ulong overlay_addr;
+	int ret;
+
+	overlay_addr = env_get_hex("extension_overlay_addr", 0);
+	if (!overlay_addr) {
+		printf("Environment extension_overlay_addr is missing\n");
+		return -EINVAL;
+	}
+
+	fdt_shrink_to_minimum(working_fdt, size);
+
+	blob = map_sysmem(overlay_addr, 0);
+	if (!fdt_valid(&blob)) {
+		printf("Invalid overlay devicetree\n");
+		return -EINVAL;
+	}
+
+	/* Apply method prints messages on error */
+	ret = fdt_overlay_apply_verbose(working_fdt, blob);
+	if (ret)
+		printf("Failed to apply overlay\n");
+
+	return ret;
+}
+
+UCLASS_DRIVER(extension) = {
+	.name	= "extension",
+	.id	= UCLASS_EXTENSION,
+};

boot/pxe_utils.c

@@ -10,6 +10,7 @@
 #include <command.h>
 #include <dm.h>
 #include <env.h>
+#include <extension_board.h>
 #include <image.h>
 #include <log.h>
 #include <malloc.h>
@@ -432,6 +433,95 @@ skip_overlay:
 }
 #endif
 
+/*
+ * label_boot_extension - scan extension boards and load overlay associated
+ */
+
+static void label_boot_extension(struct pxe_context *ctx,
+				 struct pxe_label *label)
+{
+#if CONFIG_IS_ENABLED(SUPPORT_EXTENSION_SCAN)
+	const struct extension *extension;
+	struct fdt_header *working_fdt;
+	struct alist *extension_list;
+	int ret, dir_len, len;
+	char *overlay_dir;
+	const char *slash;
+	ulong fdt_addr;
+
+	ret = extension_scan();
+	if (ret < 0)
+		return;
+
+	extension_list = extension_get_list();
+	if (!extension_list)
+		return;
+
+	/* Get the main fdt and map it */
+	fdt_addr = env_get_hex("fdt_addr_r", 0);
+	working_fdt = map_sysmem(fdt_addr, 0);
+	if (fdt_check_header(working_fdt))
+		return;
+
+	/* Use fdtdir for now as the overlay devicetree directory */
+	if (label->fdtdir) {
+		len = strlen(label->fdtdir);
+		if (!len)
+			slash = "./";
+		else if (label->fdtdir[len - 1] != '/')
+			slash = "/";
+		else
+			slash = "";
+
+		dir_len = strlen(label->fdtdir) + strlen(slash) + 1;
+		overlay_dir = calloc(1, len);
+		if (!overlay_dir)
+			return;
+
+		snprintf(overlay_dir, dir_len, "%s%s", label->fdtdir,
+			 slash);
+	} else {
+		dir_len = 2;
+		snprintf(overlay_dir, dir_len, "/");
+	}
+
+	alist_for_each(extension, extension_list) {
+		char *overlay_file;
+		ulong size;
+
+		len = dir_len + strlen(extension->overlay);
+		overlay_file = calloc(1, len);
+		if (!overlay_file)
+			goto cleanup;
+
+		snprintf(overlay_file, len, "%s%s", overlay_dir,
+			 extension->overlay);
+
+		/* Load extension overlay file */
+		ret = get_relfile_envaddr(ctx, overlay_file,
+					  "extension_overlay_addr",
+					  (enum bootflow_img_t)IH_TYPE_FLATDT,
+					  &size);
+		if (ret < 0) {
+			printf("Failed loading overlay %s\n", overlay_file);
+			free(overlay_file);
+			continue;
+		}
+
+		ret = extension_apply(working_fdt, size);
+		if (ret) {
+			printf("Failed applying overlay %s\n", overlay_file);
+			free(overlay_file);
+			continue;
+		}
+		free(overlay_file);
+	}
+
+cleanup:
+	free(overlay_dir);
+#endif
+}
+
 /**
  * label_boot() - Boot according to the contents of a pxe_label
  *
@@ -685,6 +775,8 @@ static int label_boot(struct pxe_context *ctx, struct pxe_label *label)
 			if (label->fdtoverlays)
 				label_boot_fdtoverlay(ctx, label);
 #endif
+			label_boot_extension(ctx, label);
+
 		} else {
 			bootm_argv[3] = NULL;
 		}