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[2620:137:e000::1:20]) by mx.google.com with ESMTP id ha4-20020a17090af3c400b00237413f8c6esi5423547pjb.154.2023.03.16.22.50.53; Thu, 16 Mar 2023 22:51:09 -0700 (PDT) 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=lClEe3QY; 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 S230028AbjCQFef (ORCPT + 99 others); Fri, 17 Mar 2023 01:34:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60108 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229879AbjCQFea (ORCPT ); Fri, 17 Mar 2023 01:34:30 -0400 Received: from mail-qt1-x834.google.com (mail-qt1-x834.google.com [IPv6:2607:f8b0:4864:20::834]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3BCE6768C; Thu, 16 Mar 2023 22:34:29 -0700 (PDT) Received: by mail-qt1-x834.google.com with SMTP id ek9so4536161qtb.10; Thu, 16 Mar 2023 22:34:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1679031268; 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=9REZkhiENtutm2XWIH1dQvVKSfKRddJL/3DZpRuUkWI=; b=lClEe3QYl0olxODsxeRKQ/9GrkyopZPsCQqWIyLKjYRQhbVfBjYsQDR5awxURhaUqh GddUuaBNVSfZ+aHbSHQIMUavS4pU1Dcbt+07bCChTKjQwX9JhzmMCGCrXkUEsDl+xZ2u NwsXvtUnreREItuVepUKiCFJzcVQxMrlypG5/sgo9xn3RVHrQbUJuIqNkhMPdMQalTnl r9RKwPkWJbz5ZvkWLaEp4bICNDi3lzaOVb1raG90vQQ08874pcHgcOfuvpdYeXoZPQ3V T0fTpw1V9NPFbGheceYDO4v1VkXwf8TZiRkhvWB9HClruc/hzjvtg2nQcC/154leZpG/ H6eQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1679031268; 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=9REZkhiENtutm2XWIH1dQvVKSfKRddJL/3DZpRuUkWI=; b=BUVuV+OXr2dh2nez/Y7uUQFu0zaKE1eicS+m04KVYLaSkbDgNa1XCh9RVWQaFIBs+V Gc8aQSKIMHPsiGMBaz5wfxsPLhnDlltkUpeQI24aZsgCGglxAZCkL2BqYDlkes+VB7Fs bY9QBPIXBihX2zOBHxGYmWkXAsLrP1nidPnXUBmZNYRkG4MNZzIfFprSmBYkyT5qKdkt tgGfdn+qbhmHeiBI0U2MvmGVyzn1hYhHQcvXYLad4eh6MBllVgyftxNU0mfbXeK7tbH8 a8NDefAU+u9dXt5YVi8I6XJklPkq4qX8A85yOilaUUWg2rnjQ3ahWbrJgL7GBSHYfCoh wSqA== X-Gm-Message-State: AO0yUKUcBSf5ll73Jm4W/mT9ItHA+MnLcdBJSvFSuVfQarpc5mC29EBU I9HLt+n0KUFfWkvp7Z2YugE= X-Received: by 2002:ac8:7f8c:0:b0:3bf:b1d0:ab88 with SMTP id z12-20020ac87f8c000000b003bfb1d0ab88mr9894988qtj.5.1679031268305; Thu, 16 Mar 2023 22:34:28 -0700 (PDT) Received: from xps8900.attlocal.net ([2600:1700:2442:6db0:557c:9772:415e:adc7]) by smtp.gmail.com with ESMTPSA id i5-20020ac860c5000000b003b34650039bsm737649qtm.76.2023.03.16.22.34.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Mar 2023 22:34:27 -0700 (PDT) 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 v4 1/2] of: create of_root if no dtb provided Date: Fri, 17 Mar 2023 00:34:14 -0500 Message-Id: <20230317053415.2254616-2-frowand.list@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230317053415.2254616-1-frowand.list@gmail.com> References: <20230317053415.2254616-1-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?1760592941017995223?= X-GMAIL-MSGID: =?utf-8?q?1760592941017995223?= 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(), 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 3: - refresh for 6.3-rc1 - unflatten_device_tree() - calculate of_fdt_crc32 if setting initial_boot_params to __dtb_empty_root_begin so CRC check in of_fdt_raw_init() will not fail 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 | 29 ++++++++++++++++++++++++++++- include/linux/of_fdt.h | 2 ++ init/main.c | 2 ++ 6 files changed, 45 insertions(+), 3 deletions(-) create mode 100644 drivers/of/empty_root.dts diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig index 644386833a7b..194e090ceee8 100644 --- a/drivers/of/Kconfig +++ b/drivers/of/Kconfig @@ -54,9 +54,14 @@ 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 d1a68b6d03b3..f65016c2e79f 100644 --- a/drivers/of/fdt.c +++ b/drivers/of/fdt.c @@ -32,6 +32,13 @@ #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 +1333,21 @@ 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; + } + of_fdt_crc32 = crc32_be(~0, initial_boot_params, + fdt_totalsize(initial_boot_params)); + 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 +1387,13 @@ 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 4425d1783d5c..3c443e0c5927 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();