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=-12.8 required=3.0 tests=BAYES_00,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=unavailable 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 63577C2BC11 for ; Tue, 8 Sep 2020 20:33:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D244E20936 for ; Tue, 8 Sep 2020 20:33:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=alliedtelesis.co.nz header.i=@alliedtelesis.co.nz header.b="ZIyCzS7y" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730168AbgIHUdC (ORCPT ); Tue, 8 Sep 2020 16:33:02 -0400 Received: from gate2.alliedtelesis.co.nz ([202.36.163.20]:46642 "EHLO gate2.alliedtelesis.co.nz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726272AbgIHUdC (ORCPT ); Tue, 8 Sep 2020 16:33:02 -0400 Received: from mmarshal3.atlnz.lc (mmarshal3.atlnz.lc [10.32.18.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by gate2.alliedtelesis.co.nz (Postfix) with ESMTPS id C05EA806B5; Wed, 9 Sep 2020 08:32:56 +1200 (NZST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alliedtelesis.co.nz; s=mail181024; t=1599597176; bh=rwV/xSJfjutzpYJ4zBUGBqee/pB4wUosVEzaIEIqS9w=; h=From:To:Cc:Subject:Date; b=ZIyCzS7yW2Fo+L0Hw6H+bFNw1YTAUzoX5gn3nTdUwHErTvGcHKP7gvMZU2RH0ZkKr I6FAzR3SNBSvSJJV/Sh/WNEO8d72Tk5QVpr13MnGKRE8SDPaVgtKYXJM6UsC78Rw+P sozudACqIdLxX6t3kNhtUhnDvQaNbh+Aa/oJDcS2uqFxpnl3LMwL2QVJhBnunweFLs Wxf9t4jxTlyqE9JVPVCHTOriqOchbme7mpRtG+CG0RgPe3X67ywZORLP7vNHYC9tSK +WyN9Zeij0S8q5OCPeEIKFm5Gk+8yLjWmN3jLlu9jpUrxBhPkIpmt32oBXBqkXKaNF vShDaCRF2OTQw== Received: from smtp (Not Verified[10.32.16.33]) by mmarshal3.atlnz.lc with Trustwave SEG (v7,5,8,10121) id ; Wed, 09 Sep 2020 08:32:55 +1200 Received: from evann-dl.ws.atlnz.lc (evann-dl.ws.atlnz.lc [10.33.23.31]) by smtp (Postfix) with ESMTP id 5833C13EEB7; Wed, 9 Sep 2020 08:32:56 +1200 (NZST) Received: by evann-dl.ws.atlnz.lc (Postfix, from userid 1780) id 79E4D1A4E97; Wed, 9 Sep 2020 08:32:56 +1200 (NZST) From: Evan Nimmo To: wsa@kernel.org, andriy.shevchenko@linux.intel.com, chris.packham@alliedtelesis.co.nz, jarkko.nikula@linux.intel.com, jdelvare@suse.de Cc: linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, Evan Nimmo Subject: [PATCH v4 1/1] i2c: algo-pca: Reapply i2c bus settings after reset Date: Wed, 9 Sep 2020 08:32:47 +1200 Message-Id: <20200908203247.14374-1-evan.nimmo@alliedtelesis.co.nz> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable x-atlnz-ls: pat Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If something goes wrong (such as the SCL being stuck low) then we need to reset the PCA chip. The issue with this is that on reset we lose all config settings and the chip ends up in a disabled state which results in a lock up/high CPU usage. We need to re-apply any configuration that had previously been set and re-enable the chip. Signed-off-by: Evan Nimmo Reviewed-by: Chris Packham Reviewed-by: Andy Shevchenko Reviewed-by: Wolfram Sang --- changes in v2: - changed lowercase "pca to uppercase "PCA". - reworded and reformatted the multiline comment. - moved the clock frequency KERN_INFO closer to the call that sets this. - moved the i2c_bus_settings struct to the more generic i2c.h and removed - the comments indicating this as being for the pca chip. changes in v3: - changed lowercase "cpu" to uppercase "CPU". changes in v4: - renamed the struct i2c_bus_settings struct to struct pca_i2c_bus_settin= gs. - moved the struct pca_i2c_bus_settings struct from i2c.h to i2c-algo-pca= .h. - adjusted the struct field in the struct i2c_algo_pca_data struct to be = of type - struct pca_i2c_bus settings. - removed an extra line in i2c-algo-pca.c drivers/i2c/algos/i2c-algo-pca.c | 35 +++++++++++++++++++++----------- include/linux/i2c-algo-pca.h | 15 ++++++++++++++ 2 files changed, 38 insertions(+), 12 deletions(-) diff --git a/drivers/i2c/algos/i2c-algo-pca.c b/drivers/i2c/algos/i2c-alg= o-pca.c index 710fbef9a9c2..384af88e58ad 100644 --- a/drivers/i2c/algos/i2c-algo-pca.c +++ b/drivers/i2c/algos/i2c-algo-pca.c @@ -41,8 +41,22 @@ static void pca_reset(struct i2c_algo_pca_data *adap) pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IPRESET); pca_outw(adap, I2C_PCA_IND, 0xA5); pca_outw(adap, I2C_PCA_IND, 0x5A); + + /* + * After a reset we need to re-apply any configuration + * (calculated in pca_init) to get the bus in a working state. + */ + pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_IMODE); + pca_outw(adap, I2C_PCA_IND, adap->bus_settings.mode); + pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_ISCLL); + pca_outw(adap, I2C_PCA_IND, adap->bus_settings.tlow); + pca_outw(adap, I2C_PCA_INDPTR, I2C_PCA_ISCLH); + pca_outw(adap, I2C_PCA_IND, adap->bus_settings.thi); + + pca_set_con(adap, I2C_PCA_CON_ENSIO); } else { adap->reset_chip(adap->data); + pca_set_con(adap, I2C_PCA_CON_ENSIO | adap->bus_settings.clock_freq); } } =20 @@ -423,13 +437,14 @@ static int pca_init(struct i2c_adapter *adap) " Use the nominal frequency.\n", adap->name); } =20 - pca_reset(pca_data); - clock =3D pca_clock(pca_data); printk(KERN_INFO "%s: Clock frequency is %dkHz\n", adap->name, freqs[clock]); =20 - pca_set_con(pca_data, I2C_PCA_CON_ENSIO | clock); + /* Store settings as these will be needed when the PCA chip is reset *= / + pca_data->bus_settings.clock_freq =3D clock; + + pca_reset(pca_data); } else { int clock; int mode; @@ -496,19 +511,15 @@ static int pca_init(struct i2c_adapter *adap) thi =3D tlow * min_thi / min_tlow; } =20 + /* Store settings as these will be needed when the PCA chip is reset *= / + pca_data->bus_settings.mode =3D mode; + pca_data->bus_settings.tlow =3D tlow; + pca_data->bus_settings.thi =3D thi; + pca_reset(pca_data); =20 printk(KERN_INFO "%s: Clock frequency is %dHz\n", adap->name, clock * 100); - - pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_IMODE); - pca_outw(pca_data, I2C_PCA_IND, mode); - pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLL); - pca_outw(pca_data, I2C_PCA_IND, tlow); - pca_outw(pca_data, I2C_PCA_INDPTR, I2C_PCA_ISCLH); - pca_outw(pca_data, I2C_PCA_IND, thi); - - pca_set_con(pca_data, I2C_PCA_CON_ENSIO); } udelay(500); /* 500 us for oscillator to stabilise */ =20 diff --git a/include/linux/i2c-algo-pca.h b/include/linux/i2c-algo-pca.h index d03071732db4..7c522fdd9ea7 100644 --- a/include/linux/i2c-algo-pca.h +++ b/include/linux/i2c-algo-pca.h @@ -53,6 +53,20 @@ #define I2C_PCA_CON_SI 0x08 /* Serial Interrupt */ #define I2C_PCA_CON_CR 0x07 /* Clock Rate (MASK) */ =20 +/** + * struct pca_i2c_bus_settings - The configured PCA i2c bus settings + * @mode: Configured i2c bus mode + * @tlow: Configured SCL LOW period + * @thi: Configured SCL HIGH period + * @clock_freq: The configured clock frequency + */ +struct pca_i2c_bus_settings { + int mode; + int tlow; + int thi; + int clock_freq; +}; + struct i2c_algo_pca_data { void *data; /* private low level data */ void (*write_byte) (void *data, int reg, int val); @@ -64,6 +78,7 @@ struct i2c_algo_pca_data { * For PCA9665, use the frequency you want here. */ unsigned int i2c_clock; unsigned int chip; + struct pca_i2c_bus_settings bus_settings; }; =20 int i2c_pca_add_bus(struct i2c_adapter *); --=20 2.27.0