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 X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C03AAFA3737 for ; Thu, 17 Oct 2019 11:49:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 97D4A2082C for ; Thu, 17 Oct 2019 11:49:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=rasmusvillemoes.dk header.i=@rasmusvillemoes.dk header.b="SBcX2tI4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2502146AbfJQLtW (ORCPT ); Thu, 17 Oct 2019 07:49:22 -0400 Received: from mail-lj1-f196.google.com ([209.85.208.196]:36248 "EHLO mail-lj1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2502101AbfJQLtS (ORCPT ); Thu, 17 Oct 2019 07:49:18 -0400 Received: by mail-lj1-f196.google.com with SMTP id v24so2227287ljj.3 for ; Thu, 17 Oct 2019 04:49:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rasmusvillemoes.dk; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=a+GxmprIIlivls+xiiE2BlDUBLKsv4nmlWzvKE4aR9Y=; b=SBcX2tI4x4/1Q7OpymRwhlxB/kdYjwCirEuibHX7DawgeJTuPaHyxNMLNh4W9MVyBF letoHX64UHC4ruCNszUwvKalaZpVG78M22y3d3Vq8FVk+S+V7nQJVOE9LlNTM/rcST4N OLyB3dRj3YA71fYRagSSWlZZTUNlAHC7+YCZs= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=a+GxmprIIlivls+xiiE2BlDUBLKsv4nmlWzvKE4aR9Y=; b=QycPx1lMYd22rJr5aO3wX/8T8fZS5jVKMrJrAzxC+WBpWSIhu07y516haUfxx7xcOx NGXH789jj+7QYzx4sxs0gkiETkczFSgcV3ExJIyrFl0+66J7i0MkfbISA7n3GM0X5z9Q 9lr53ZvErrF1ZQg4TaZezj9oOJaD3Q3DDoPQ2uZrJk3FJh/Ay0aP/+1WGq3tFmvgftlB EwTwQG9f4slb1Ssnyl7Pe3QhY65gl8G68tLRc1yjSCGgRc/4zA81MCRqubNBcM6EFc6C GYYOcMHHm39LR0P1fEHx5G0WxOcgjbzXLf/jsg1GWm8hY5qR+ZaQUmjnUB5beTF0x12s 46Mw== X-Gm-Message-State: APjAAAWrfsl1LGi9svLLCS6HUCLuwKMmVoFIZSEriFdQOrHkmzZnsXmx xPP0w4Xdnh5kVid+CLbCeZsm0g== X-Google-Smtp-Source: APXvYqxGLJtJkNX4m2MxleJ2gGPlrbCblZIvrattCDK3O6KMUbntqKBn9afoSuGTNTeqmCY1Gi1qOw== X-Received: by 2002:a05:651c:8b:: with SMTP id 11mr2229402ljq.98.1571312956132; Thu, 17 Oct 2019 04:49:16 -0700 (PDT) Received: from prevas-ravi.prevas.se ([81.216.59.226]) by smtp.gmail.com with ESMTPSA id x30sm920772ljd.39.2019.10.17.04.49.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Oct 2019 04:49:15 -0700 (PDT) From: Rasmus Villemoes To: Masahiro Yamada , Andrew Morton , Gao Xiang Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Linus Walleij , kernel@pengutronix.de, Rasmus Villemoes Subject: [RFC PATCH 3/3] decompress/keepalive.h: add config option for toggling a set of bits Date: Thu, 17 Oct 2019 13:49:06 +0200 Message-Id: <20191017114906.30302-4-linux@rasmusvillemoes.dk> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191017114906.30302-1-linux@rasmusvillemoes.dk> References: <20191017114906.30302-1-linux@rasmusvillemoes.dk> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It's quite common to have an external watchdog which is serviced via flipping a GPIO, with the value of that GPIO being settable directly in a memory-mapped register. So add kconfig options defining the physical address of such a register as well as a mask to have the decompressor periodically xor into that register. If and when other decompress_keepalive methods are added, this can be made into a "choice DECOMPRESS_KEEPALIVE". Since only LZ4 is wired up currently, this is "depends on KERNEL_LZ4" for now. Also, prevent this option from being shown to the average user. Signed-off-by: Rasmus Villemoes --- include/linux/decompress/keepalive.h | 8 +++++++ init/Kconfig | 33 ++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+) diff --git a/include/linux/decompress/keepalive.h b/include/linux/decompress/keepalive.h index 39caa7693624..c62e49bee7cf 100644 --- a/include/linux/decompress/keepalive.h +++ b/include/linux/decompress/keepalive.h @@ -5,6 +5,14 @@ #ifdef PREBOOT +#ifdef CONFIG_DECOMPRESS_KEEPALIVE_TOGGLE +#define decompress_keepalive() do { \ + long addr = CONFIG_DECOMPRESS_KEEPALIVE_TOGGLE_REG; \ + volatile unsigned *reg = (volatile unsigned *)addr; \ + *reg ^= CONFIG_DECOMPRESS_KEEPALIVE_TOGGLE_MASK; \ +} while (0) +#endif + #endif #ifndef decompress_keepalive diff --git a/init/Kconfig b/init/Kconfig index b4daad2bac23..8a894d9fdd77 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -289,6 +289,39 @@ config KERNEL_UNCOMPRESSED endchoice +config DECOMPRESS_KEEPALIVE_TOGGLE + depends on KERNEL_LZ4 + depends on EXPERT + bool "Toggle some bits while decompressing" + help + Some embedded boards have an always-running hardware + watchdog with a timeout short enough that the board is reset + during decompression, thus preventing the board from ever + booting. + + Enable this to toggle certain bits in a memory register + while decompressing the kernel. This can for example be used + in the common case of an external watchdog serviced via a + memory-mapped GPIO. + + Say N unless you know you need this. + +if DECOMPRESS_KEEPALIVE_TOGGLE + +config DECOMPRESS_KEEPALIVE_TOGGLE_REG + hex "Address of register to modify while decompressing" + help + Set this to a physical address of a 32-bit memory word to + modify while decompressing. + +config DECOMPRESS_KEEPALIVE_TOGGLE_MASK + hex "Bit mask to toggle while decompressing" + help + The register selected above will periodically be xor'ed with + this value during decompression. + +endif + config DEFAULT_HOSTNAME string "Default hostname" default "(none)" -- 2.20.1