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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9B550C43217 for ; Wed, 13 Oct 2021 00:55:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8622E60EBB for ; Wed, 13 Oct 2021 00:55:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236694AbhJMA5e (ORCPT ); Tue, 12 Oct 2021 20:57:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:40996 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236508AbhJMA5M (ORCPT ); Tue, 12 Oct 2021 20:57:12 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id AFAC760EBB; Wed, 13 Oct 2021 00:55:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1634086510; bh=tZDxhnml6J/pYC6SCT4v70fUfCAV5raH4h8fIzLk93Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZDyEYj6DMaiqbsSKSmXy5nLe2YQ/7uAqpJcPFR65v5Vm35h7umptIOBcrBSA3S0gK pX7LYSTe2nTW7hm1s8savespRc+31mL7EFcRO44BzqkruWxK2fV3tNwVPWm3uxBePS LBl/2vtsHzC/0rxmovxj909UvnlfovNyUHjR3P/snZL5AVB72YKz5oCOV9HIwWZuqB YalOzFHVfjNHxP073hI25VCR688Vbb1GZNKnMpM25PjtcxASVOR8smIgd+a/tZvvQi GkNA0yroHgYwjTVrw0NBpiLElrrCUSueTJopY0++pUqCGTSPhr8gMlxaFS8YSsF+K4 X9P+iN8f93D4g== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Guenter Roeck , Max Filippov , Sasha Levin , chris@zankel.net, linux-xtensa@linux-xtensa.org Subject: [PATCH AUTOSEL 5.14 11/17] xtensa: xtfpga: Try software restart before simulating CPU reset Date: Tue, 12 Oct 2021 20:54:35 -0400 Message-Id: <20211013005441.699846-11-sashal@kernel.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20211013005441.699846-1-sashal@kernel.org> References: <20211013005441.699846-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Guenter Roeck [ Upstream commit 012e974501a270d8dfd4ee2039e1fdf7579c907e ] Rebooting xtensa images loaded with the '-kernel' option in qemu does not work. When executing a reboot command, the qemu session either hangs or experiences an endless sequence of error messages. Kernel panic - not syncing: Unrecoverable error in exception handler Reset code jumps to the CPU restart address, but Linux can not recover from there because code and data in the kernel init sections have been discarded and overwritten at this point. XTFPGA platforms have a means to reset the CPU by writing 0xdead into a specific FPGA IO address. When used in QEMU the kernel image loaded with the '-kernel' option gets restored to its original state allowing the machine to boot successfully. Use that mechanism to attempt a platform reset. If it does not work, fall back to the existing mechanism. Signed-off-by: Guenter Roeck Signed-off-by: Max Filippov Signed-off-by: Sasha Levin --- arch/xtensa/platforms/xtfpga/setup.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/xtensa/platforms/xtfpga/setup.c b/arch/xtensa/platforms/xtfpga/setup.c index 59b7f11f2a3e..538e6748e85a 100644 --- a/arch/xtensa/platforms/xtfpga/setup.c +++ b/arch/xtensa/platforms/xtfpga/setup.c @@ -51,8 +51,12 @@ void platform_power_off(void) void platform_restart(void) { - /* Flush and reset the mmu, simulate a processor reset, and - * jump to the reset vector. */ + /* Try software reset first. */ + WRITE_ONCE(*(u32 *)XTFPGA_SWRST_VADDR, 0xdead); + + /* If software reset did not work, flush and reset the mmu, + * simulate a processor reset, and jump to the reset vector. + */ cpu_reset(); /* control never gets here */ } -- 2.33.0