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[2620:137:e000::1:20]) by mx.google.com with ESMTP id z13-20020a1709027e8d00b001944e99d38fsi14306830pla.557.2023.02.21.20.08.12; Tue, 21 Feb 2023 20:08:24 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b=IkuNEjha; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231577AbjBVDzc (ORCPT + 99 others); Tue, 21 Feb 2023 22:55:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44642 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231515AbjBVDz1 (ORCPT ); Tue, 21 Feb 2023 22:55:27 -0500 Received: from mail-ot1-x335.google.com (mail-ot1-x335.google.com [IPv6:2607:f8b0:4864:20::335]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7EE5F31E2C; Tue, 21 Feb 2023 19:55:25 -0800 (PST) Received: by mail-ot1-x335.google.com with SMTP id e18-20020a0568301e5200b00690e6abbf3fso1490095otj.13; Tue, 21 Feb 2023 19:55:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=Dl7cNlq6eol+0bH4dQvHPF1M13TBElOJT4S6JzbFEnE=; b=IkuNEjhaZ1PliD2souixHHwtTrSoR5WGyijs3MJtI9lJq1LNy+Nx3s7KrddRG47is5 At8xhnJy3a5RZmCurWUZk58LX5QFfQwHzh7ulG1DKATiHw3Z9bgtb0+k2eDnR1gZpQMS K31c1ifrAiCOjTXZLjKeJB8YUPIMf9huqqyDLm1GecnjAOILwZlj5RYhb/YpSyD8wfPQ qgTWIQJP2hiuKCHw3jY7M9PWMrIWTAek7kKbCsdmPEEv7PZmPUfsvJziV0tFJT3SJV/R p/YVa1RjegYanaOCbGbJEZzQop/SFMxG5vd9VPCmv9PRMMVAkFsQrRxRtL9F/XJf2RH3 DCHw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=Dl7cNlq6eol+0bH4dQvHPF1M13TBElOJT4S6JzbFEnE=; b=YIFR6SnsVtSQmfkP4a824GdCz913nW9pgf6EYqDR0o0ej4MA7BlitJC0n+Bz4GoI+c qDeo3bwJdd+5hbBdXLETlC1ACSCRRdrP7BV/SbJVAUDWlkqDNHRuSm1zk7bsh3MRlzeA FZAlD9U+uZvWK898kUzTLXwZVPncYvC85MZHpBKNVNXDUfTIZX2irVCtMpGFI8IkyWUr xrSvaiU50GSQtQzly4o+eMTLzWFJ3zfzU2BcInCRnasOq4QaVROTzdbeMwPtKsoY7YEf EOjVn92/uqSlVkIMNHTPp9MudSIDgrHKVwRohgx76UiPNE5s97twq39LVXbBuKJyy4Pl hFvw== X-Gm-Message-State: AO0yUKVmIEbRwbfMUsMCo1quHnZnJT66bUYh7TQvjv30zo+YfznJ7oz9 BLIHwWrPYbyEf2523BRzFAU= X-Received: by 2002:a05:6830:448b:b0:690:e27f:3200 with SMTP id r11-20020a056830448b00b00690e27f3200mr4176729otv.12.1677038124818; Tue, 21 Feb 2023 19:55:24 -0800 (PST) Received: from xps8900.attlocal.net ([2600:1700:2442:6db0:70ac:b1e4:53db:3994]) by smtp.gmail.com with ESMTPSA id y6-20020a056830070600b00684cbd8dd49sm533404ots.79.2023.02.21.19.55.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Feb 2023 19:55:24 -0800 (PST) From: Frank Rowand To: Rob Herring , =?utf-8?b?Q2zDqW1lbnQgTMOpZ2Vy?= 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: Tue, 21 Feb 2023 21:54:51 -0600 Message-Id: <20230222035452.803375-2-frowand.list@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230222035452.803375-1-frowand.list@gmail.com> References: <20230222035452.803375-1-frowand.list@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM, RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1758502746862770251?= X-GMAIL-MSGID: =?utf-8?q?1758502746862770251?= 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(). Otherwise, setup_of() which is called immediately after setup_arch(), and will create the default root node if it does not exist. Signed-off-by: Frank Rowand --- There are checkpatch warnings. I have reviewed them and feel they can be ignored. Changes since version 1: - refresh for 6.2-rc1 - update Signed-off-by - fix typo in of_fdt.h: s/of_setup/setup_of - unflatten_device_tree(): validate size in header field dtb_empty_root that will be used to copy dtb_empty_root - add Kconfig option to manually select CONFIG_OF_EARLY_FLATTREE drivers/of/Kconfig | 7 ++++++- drivers/of/Makefile | 2 +- drivers/of/empty_root.dts | 6 ++++++ drivers/of/fdt.c | 27 ++++++++++++++++++++++++++- include/linux/of_fdt.h | 2 ++ init/main.c | 2 ++ 6 files changed, 43 insertions(+), 3 deletions(-) create mode 100644 drivers/of/empty_root.dts diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig index 80b5fd44ab1c..591cfe386727 100644 --- a/drivers/of/Kconfig +++ b/drivers/of/Kconfig @@ -42,9 +42,14 @@ config OF_FLATTREE select CRC32 config OF_EARLY_FLATTREE - bool + bool "Functions for accessing Flat Devicetree (FDT) early in boot" select DMA_DECLARE_COHERENT if HAS_DMA select OF_FLATTREE + help + Normally selected by platforms that process an FDT that has been + passed to the kernel by the bootloader. If the bootloader does not + pass an FDT to the kernel and you need an empty devicetree that + contains only a root node to exist, then say Y here. config OF_PROMTREE bool 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/empty_root.dts b/drivers/of/empty_root.dts new file mode 100644 index 000000000000..cf9e97a60f48 --- /dev/null +++ b/drivers/of/empty_root.dts @@ -0,0 +1,6 @@ +// SPDX-License-Identifier: GPL-2.0-only +/dts-v1/; + +/ { + +}; diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c index b2272bccf85c..0d2f6d016b7e 100644 --- a/drivers/of/fdt.c +++ b/drivers/of/fdt.c @@ -33,6 +33,13 @@ #include "of_private.h" +/* + * __dtb_empty_root_begin[] and __dtb_empty_root_end[] magically created by + * cmd_dt_S_dtb in scripts/Makefile.lib + */ +extern void *__dtb_empty_root_begin; +extern void *__dtb_empty_root_end; + /* * of_fdt_limit_memory - limit the number of regions in the /memory node * @limit: maximum entries @@ -1326,8 +1333,19 @@ 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; + /* fdt_totalsize() will be used for copy size */ + if (fdt_totalsize(initial_boot_params) > + __dtb_empty_root_end - __dtb_empty_root_begin) { + pr_err("invalid size in dtb_empty_root\n"); + return; + } + 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); @@ -1367,6 +1385,13 @@ void __init unflatten_and_copy_device_tree(void) unflatten_device_tree(); } +void __init setup_of(void) +{ + /* if architecture did not unflatten devicetree, do it now */ + 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..f0dc46d576da 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 setup_of(void) {} #endif /* CONFIG_OF_EARLY_FLATTREE */ #endif /* __ASSEMBLY__ */ diff --git a/init/main.c b/init/main.c index e1c3911d7c70..31e0931b5134 100644 --- a/init/main.c +++ b/init/main.c @@ -101,6 +101,7 @@ #include #include #include +#include #include #include @@ -961,6 +962,7 @@ 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();