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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 465D2C433B4 for ; Thu, 6 May 2021 20:54:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1645A6113E for ; Thu, 6 May 2021 20:54:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230048AbhEFUzm (ORCPT ); Thu, 6 May 2021 16:55:42 -0400 Received: from thorn.bewilderbeest.net ([71.19.156.171]:51875 "EHLO thorn.bewilderbeest.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229784AbhEFUzl (ORCPT ); Thu, 6 May 2021 16:55:41 -0400 Received: from hatter.bewilderbeest.net (unknown [IPv6:2600:6c44:7f:ba20::7c6]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: zev) by thorn.bewilderbeest.net (Postfix) with ESMTPSA id 0ADC7475; Thu, 6 May 2021 13:54:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bewilderbeest.net; s=thorn; t=1620334482; bh=vNoReDMKLGxtVQ/HUO76L61RXlajosDXB81QNCQh3t4=; h=From:To:Cc:Subject:Date:From; b=UqSiwV1TYfmc9tMThAqiUf57dvCOYSLJQ72d9rXD293X2le3KSui72Bi7EaXgth+F SZ3XSRkNJD1pRIK+AEvFsuLzpDYNjYAnAYEXHbh12wL+eLVM/m8BzDMiJetd+iLt/k HtvwZnY/7/g/PsZBOupIujs+EK+8ymakCOnzKruE= From: Zev Weiss To: Brendan Higgins Cc: Zev Weiss , Joel Stanley , Benjamin Herrenschmidt , Andrew Jeffery , linux-i2c@vger.kernel.org, openbmc@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] i2c: aspeed: disable additional device addresses on ast2[56]xx Date: Thu, 6 May 2021 15:54:19 -0500 Message-Id: <20210506205419.26294-1-zev@bewilderbeest.net> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The ast25xx and ast26xx have, respectively, two and three configurable slave device addresses to the ast24xx's one. We only support using one at a time, but the others may come up in an indeterminate state depending on hardware/bootloader behavior, so we need to make sure we disable them so as to avoid ending up with phantom devices on the bus. Signed-off-by: Zev Weiss --- Changes since v1 [0]: - reduced to simplified approach suggested by Joel [0] https://lore.kernel.org/linux-arm-kernel/20200915184525.29665-1-zev@bewilderbeest.net/ drivers/i2c/busses/i2c-aspeed.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c index 724bf30600d6..67e8b97c0c95 100644 --- a/drivers/i2c/busses/i2c-aspeed.c +++ b/drivers/i2c/busses/i2c-aspeed.c @@ -727,10 +727,14 @@ static void __aspeed_i2c_reg_slave(struct aspeed_i2c_bus *bus, u16 slave_addr) { u32 addr_reg_val, func_ctrl_reg_val; - /* Set slave addr. */ - addr_reg_val = readl(bus->base + ASPEED_I2C_DEV_ADDR_REG); - addr_reg_val &= ~ASPEED_I2CD_DEV_ADDR_MASK; - addr_reg_val |= slave_addr & ASPEED_I2CD_DEV_ADDR_MASK; + /* + * Set slave addr. Reserved bits can all safely be written with zeros + * on all of ast2[456]00, so zero everything else to ensure we only + * enable a single slave address (ast2500 has two, ast2600 has three, + * the enable bits for which are also in this register) so that we don't + * end up with additional phantom devices responding on the bus. + */ + addr_reg_val = slave_addr & ASPEED_I2CD_DEV_ADDR_MASK; writel(addr_reg_val, bus->base + ASPEED_I2C_DEV_ADDR_REG); /* Turn on slave mode. */ -- 2.31.1