From patchwork Thu Feb 23 21:34:17 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Frank Rowand X-Patchwork-Id: 657303 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 4A0E0C64ED8 for ; Thu, 23 Feb 2023 21:34:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229716AbjBWVeo (ORCPT ); Thu, 23 Feb 2023 16:34:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47212 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229706AbjBWVen (ORCPT ); Thu, 23 Feb 2023 16:34:43 -0500 Received: from mail-oa1-x33.google.com (mail-oa1-x33.google.com [IPv6:2001:4860:4864:20::33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C45D858B75; Thu, 23 Feb 2023 13:34:41 -0800 (PST) Received: by mail-oa1-x33.google.com with SMTP id 586e51a60fabf-1720887dfcdso17222611fac.6; Thu, 23 Feb 2023 13:34:41 -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=Sr4E/lNj2zE6IHIJzVZN2IPz7FoASvSZqxFSt8+h6eM=; b=f2F+FCFNTYiiT1h4c7YJZL2iuvLpnnKADnN8ASHVwMkObga2N2cS2wM/Rh+6uB0Sg6 hvLbpyxgBnnNfqI499LAFSGP0YkKQydHCi33OZT35P9mrby08Ms+VM6yMVrEIALmYPIk Yq4b5M8LNdBabDdEEFrrrHXxJ6lywnckyV6qTlGCw4qroq5PNm4nieKXsAqScf3Wqm9T MwNOeo41wqljf/8MYoxWDdppHLR2k2TXhLRMTr4XYuhMcJQX8l2bo4w/0unAd9gE7GOM Ssc4PAysCaKGQ3qphOgSR6MjY4HyDT5xCjzFxig0zRISkeD3boGCCq3C8FI6lzUCugo5 u7Hg== 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=Sr4E/lNj2zE6IHIJzVZN2IPz7FoASvSZqxFSt8+h6eM=; b=IJwG53Ng/EIvZYozZWqH2Jtwn6ePPwz77QcL6B6gA4Mukx9NS4gs8zf8mCWWemhLwH owDMnJhuc5w5bj/42gR/oeQ119WvufPMXiCU1cPKqByGkmzRGeTsMORwptmLV7bPSJT2 L6r3zApKjfpKDWdLPHv9/AnQa0VMdubzwd3Oe91cAi30uf4svBT+xz8kYRoZql0lwbJT Edx87xgB4pDQmyNdkVdPU2SvSFNQx/XaaWxQtDzwrsPiVS0c75lTU4I6TK1w4LwIILBv lLPn+RJJB/6Qkq9BsOouNkLzw2bZMtVilQ8W2jFmyg7ZLpJ7vYWaKi5iRaN1ntpvjsBW uZMQ== X-Gm-Message-State: AO0yUKUMwIbmGKxQtMjtBFNDP9Zb1dMNobVsPxk5HXROKctN16yM65DJ H8aqSzpLBYg3aanI4oFObjw= X-Google-Smtp-Source: AK7set84EQpvpgt+B6tMwCGc9ka9JNTP67E57DVQAsT3bWgJ0axLAp53BCC5ROYDX9ZwFy8Y45mioA== X-Received: by 2002:a05:6870:2155:b0:16d:e1a2:259 with SMTP id g21-20020a056870215500b0016de1a20259mr12755200oae.34.1677188081096; Thu, 23 Feb 2023 13:34:41 -0800 (PST) Received: from xps8900.attlocal.net ([2600:1700:2442:6db0:e42b:73d3:ba1a:1b32]) by smtp.gmail.com with ESMTPSA id r1-20020a4ae501000000b00524fe20aee5sm2903976oot.34.2023.02.23.13.34.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Feb 2023 13:34:40 -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 v3 1/2] of: create of_root if no dtb provided Date: Thu, 23 Feb 2023 15:34:17 -0600 Message-Id: <20230223213418.891942-2-frowand.list@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230223213418.891942-1-frowand.list@gmail.com> References: <20230223213418.891942-1-frowand.list@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org 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 --- Please wait for test results from Clement before accepting. Changes since version 2: - change of __dtb_empty_root_* from "void *" to "uint8_t []" 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..eccc2d2107af 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 uint8_t __dtb_empty_root_begin[]; +extern uint8_t __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();