From patchwork Wed Jul 8 14:35:27 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?q?Jan_L=C3=BCbbe?= X-Patchwork-Id: 6748001 Return-Path: X-Original-To: patchwork-linux-omap@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 69253C05AC for ; Wed, 8 Jul 2015 14:35:40 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 9E109206F2 for ; Wed, 8 Jul 2015 14:35:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AD5C42069E for ; Wed, 8 Jul 2015 14:35:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754521AbbGHOfi (ORCPT ); Wed, 8 Jul 2015 10:35:38 -0400 Received: from metis.ext.pengutronix.de ([92.198.50.35]:46184 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754548AbbGHOfh (ORCPT ); Wed, 8 Jul 2015 10:35:37 -0400 Received: from dude.hi.pengutronix.de ([2001:67c:670:100:1d::7]) by metis.ext.pengutronix.de with esmtps (TLS1.2:RSA_AES_128_CBC_SHA1:128) (Exim 4.80) (envelope-from ) id 1ZCoZg-0007ZG-PX; Wed, 08 Jul 2015 14:35:40 +0200 Received: from jlu by dude.hi.pengutronix.de with local (Exim 4.85) (envelope-from ) id 1ZCqRh-0007V1-49; Wed, 08 Jul 2015 16:35:33 +0200 From: Jan Luebbe To: Wolfram Sang , Tony Lindgren , Felipe Balbi Cc: linux-i2c@vger.kernel.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kernel@pengutronix.de, Jan Luebbe Subject: [PATCH] i2c: omap: fix bus recovery setup Date: Wed, 8 Jul 2015 16:35:27 +0200 Message-Id: <1436366127-24756-1-git-send-email-jlu@pengutronix.de> X-Mailer: git-send-email 2.1.4 X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::7 X-SA-Exim-Mail-From: jlu@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-omap@vger.kernel.org Sender: linux-omap-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org X-Spam-Status: No, score=-7.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP At least on the AM335x, enabling OMAP_I2C_SYSTEST_ST_EN is not enough to allow direct access to the SCL and SDA pins. In addition to ST_EN, we need to set the TMODE to 0b11 (Loop back & SDA/SCL IO mode select). Also, as the reset values of SCL_O and SDA_O are 0 (which means "drive low level"), we need to set them to 1 (which means "high-impedance") to avoid unwanted changes on the pins. As a precaution, reset all these bits to their default values after recovery is complete. Signed-off-by: Jan Luebbe Tested-by: Alexander Sverdlin Reviewed-by: Grygorii Strashko --- drivers/i2c/busses/i2c-omap.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c index d1c22e3fdd14..fc9bf7f30e35 100644 --- a/drivers/i2c/busses/i2c-omap.c +++ b/drivers/i2c/busses/i2c-omap.c @@ -1247,7 +1247,14 @@ static void omap_i2c_prepare_recovery(struct i2c_adapter *adap) u32 reg; reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG); + /* enable test mode */ reg |= OMAP_I2C_SYSTEST_ST_EN; + /* select SDA/SCL IO mode */ + reg |= 3 << OMAP_I2C_SYSTEST_TMODE_SHIFT; + /* set SCL to high-impedance state (reset value is 0) */ + reg |= OMAP_I2C_SYSTEST_SCL_O; + /* set SDA to high-impedance state (reset value is 0) */ + reg |= OMAP_I2C_SYSTEST_SDA_O; omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg); } @@ -1257,7 +1264,11 @@ static void omap_i2c_unprepare_recovery(struct i2c_adapter *adap) u32 reg; reg = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG); + /* restore reset values */ reg &= ~OMAP_I2C_SYSTEST_ST_EN; + reg &= ~OMAP_I2C_SYSTEST_TMODE_MASK; + reg &= ~OMAP_I2C_SYSTEST_SCL_O; + reg &= ~OMAP_I2C_SYSTEST_SDA_O; omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, reg); }