From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22199C43334 for ; Fri, 24 Jun 2022 03:44:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230253AbiFXDn6 (ORCPT ); Thu, 23 Jun 2022 23:43:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59834 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230179AbiFXDnr (ORCPT ); Thu, 23 Jun 2022 23:43:47 -0400 Received: from mail-qv1-xf29.google.com (mail-qv1-xf29.google.com [IPv6:2607:f8b0:4864:20::f29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A262434BB7; Thu, 23 Jun 2022 20:43:46 -0700 (PDT) Received: by mail-qv1-xf29.google.com with SMTP id t16so2993660qvh.1; Thu, 23 Jun 2022 20:43:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=G8c693hWUGJUPaGBdaxJh+jhQOSw8GXU559QqqTBvCM=; b=iSZ+Ttp73BFerzudnll/eUm+uefTUoofXz6bTlRzTfn86NgCyFMh81ZlBsxnYBETr9 Mu1+tbl3Rhr/92FNokhpf2V4MB3Kxu/lqoUE25zlbUUa8x6bwRo8BlTjm15hSSAq7wnw +8XMcZg+HNnwnadF9oj3u0PWLNvGts1rPHXC2IU9hqd7d6vm9xW3ME2G1mWXDUNU7/lD vScU4FXyI60zAijeweKJA3lOn5POG9CluiRzwAK97OibQGXJMFUsPC+wSx1JC8tshd3D EtcH3322rXjGy+iQEny5qF3zq/PUwdtoiz9o58qbBqpjXK5HKjLKcG/eC9WgMlW/3C0B JDxg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=G8c693hWUGJUPaGBdaxJh+jhQOSw8GXU559QqqTBvCM=; b=SfAsbUjflFxVphBgQdeFUtcY4obEvtb6EaYBxIrBUPvkedaQt/YS6dwKpWOw8D3yUk G8RBWP29clHIBJlrLDdjwvAOERGIB2gHYydcBYKWCDIxQDz/vPoyuxk/jRbi8VOrkusH 0ifRzIw6gG5eMvAxmqJS5gOOHFBAJaT9ZwMjWTvGtXaz0i5ppKoaSQXviYbcW3OxFmso VKqgNTzknB3TToZM7yqopF/TjjEQVYGYpypv71gM2iehMfYErFI2CqsA44MFdQUGmy/+ khIazZ7OhSRZ8cwn7+n9lUNW0OnaRjQbNyBmNmgESzSiHfqQ63NMq9Q+p+n2IEQKjB3H DAAg== X-Gm-Message-State: AJIora/xOcxTR5nvx81IGui3QyXJIpU+1LAVGo3Dje/Y75rPFbI1+yR6 bBc0PHFZNQBHGbndRxZkIsdAxKGcYPtnkQ== X-Google-Smtp-Source: AGRyM1u7H7UmwToZUqRExOjslgxS3zVf07WMUdkfsMT6/JFCuGjoLP/Sb3cQ0i0c8RHGpAi069+uZQ== X-Received: by 2002:a05:6214:e42:b0:470:5138:a496 with SMTP id o2-20020a0562140e4200b004705138a496mr15647895qvc.100.1656042225543; Thu, 23 Jun 2022 20:43:45 -0700 (PDT) Received: from xps8900.attlocal.net ([2600:1700:2442:6db0:bdf1:2a9b:4f43:67ef]) by smtp.gmail.com with ESMTPSA id u3-20020a05620a454300b006aef6a244a4sm1048691qkp.129.2022.06.23.20.43.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Jun 2022 20:43:42 -0700 (PDT) From: frowand.list@gmail.com To: Rob Herring , =?UTF-8?q?Cl=C3=A9ment=20L=C3=A9ger?= Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Lizhi Hou , Allan Nielsen , Horatiu Vultur , Steen Hegelund , Thomas Petazzoni Subject: [PATCH 1/2] of: create of_root if no dtb provided Date: Thu, 23 Jun 2022 22:43:26 -0500 Message-Id: <20220624034327.2542112-2-frowand.list@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220624034327.2542112-1-frowand.list@gmail.com> References: <20220624034327.2542112-1-frowand.list@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Frank Rowand When enabling CONFIG_OF on a platform where of_root is not populated by firmware, we end up without a root node. In order to apply overlays and create subnodes of the root node, we need one. Create this root node by unflattening an empty builtin dtb. If firmware provides a flattened device tree (FDT) then the FDT is unflattened via setup_arch(). setup_of() is called immediately after setup_arch(), and will create the default root node if it does not exist. Signed-off-by: Frank Rowand --- This patch modifies init/main.c. It was not clear to me whether to add Linus to the distribution, or if the change should flow through Rob. (I did not add Linus.) drivers/of/Makefile | 2 +- drivers/of/fdt.c | 19 ++++++++++++++++++- include/linux/of_fdt.h | 2 ++ init/main.c | 2 ++ 4 files changed, 23 insertions(+), 2 deletions(-) diff --git a/drivers/of/Makefile b/drivers/of/Makefile index e0360a44306e..cbae92c5ed02 100644 --- a/drivers/of/Makefile +++ b/drivers/of/Makefile @@ -2,7 +2,7 @@ obj-y = base.o device.o platform.o property.o obj-$(CONFIG_OF_KOBJ) += kobj.o obj-$(CONFIG_OF_DYNAMIC) += dynamic.o -obj-$(CONFIG_OF_FLATTREE) += fdt.o +obj-$(CONFIG_OF_FLATTREE) += fdt.o empty_root.dtb.o obj-$(CONFIG_OF_EARLY_FLATTREE) += fdt_address.o obj-$(CONFIG_OF_PROMTREE) += pdt.o obj-$(CONFIG_OF_ADDRESS) += address.o diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c index a8f5b6532165..d439ded3b6c6 100644 --- a/drivers/of/fdt.c +++ b/drivers/of/fdt.c @@ -33,6 +33,12 @@ #include "of_private.h" +/* + * __dtb_empty_root_begin[] magically created by cmd_dt_S_dtb in + * scripts/Makefile.lib + */ +extern void *__dtb_empty_root_begin; + /* * of_fdt_limit_memory - limit the number of regions in the /memory node * @limit: maximum entries @@ -1332,8 +1338,13 @@ bool __init early_init_dt_scan(void *params) */ void __init unflatten_device_tree(void) { - __unflatten_device_tree(initial_boot_params, NULL, &of_root, + if (!initial_boot_params) { + initial_boot_params = (void *) __dtb_empty_root_begin; + unflatten_and_copy_device_tree(); + } else { + __unflatten_device_tree(initial_boot_params, NULL, &of_root, early_init_dt_alloc_memory_arch, false); + } /* Get pointer to "/chosen" and "/aliases" nodes for use everywhere */ of_alias_scan(early_init_dt_alloc_memory_arch); @@ -1373,6 +1384,12 @@ void __init unflatten_and_copy_device_tree(void) unflatten_device_tree(); } +void __init setup_of(void) +{ + if (!of_root) + unflatten_device_tree(); +} + #ifdef CONFIG_SYSFS static ssize_t of_fdt_raw_read(struct file *filp, struct kobject *kobj, struct bin_attribute *bin_attr, diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h index d69ad5bb1eb1..4566876db351 100644 --- a/include/linux/of_fdt.h +++ b/include/linux/of_fdt.h @@ -81,6 +81,7 @@ extern const void *of_flat_dt_match_machine(const void *default_match, /* Other Prototypes */ extern void unflatten_device_tree(void); extern void unflatten_and_copy_device_tree(void); +extern void setup_of(void); extern void early_init_devtree(void *); extern void early_get_first_memblock_info(void *, phys_addr_t *); #else /* CONFIG_OF_EARLY_FLATTREE */ @@ -91,6 +92,7 @@ static inline void early_init_fdt_reserve_self(void) {} static inline const char *of_flat_dt_get_machine_name(void) { return NULL; } static inline void unflatten_device_tree(void) {} static inline void unflatten_and_copy_device_tree(void) {} +static inline void of_setup(void) {} #endif /* CONFIG_OF_EARLY_FLATTREE */ #endif /* __ASSEMBLY__ */ diff --git a/init/main.c b/init/main.c index 0ee39cdcfcac..8b3a60d14bea 100644 --- a/init/main.c +++ b/init/main.c @@ -99,6 +99,7 @@ #include #include #include +#include #include #include @@ -949,6 +950,7 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void) pr_notice("%s", linux_banner); early_security_init(); setup_arch(&command_line); + setup_of(); setup_boot_config(); setup_command_line(command_line); setup_nr_cpu_ids(); -- Frank Rowand