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=-15.5 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 306FAC4361B for ; Sun, 13 Dec 2020 17:21:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 07FAD23380 for ; Sun, 13 Dec 2020 17:21:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2437478AbgLMRV2 (ORCPT ); Sun, 13 Dec 2020 12:21:28 -0500 Received: from mail.kernel.org ([198.145.29.99]:39426 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2395405AbgLMRV2 (ORCPT ); Sun, 13 Dec 2020 12:21:28 -0500 Received: from archlinux (cpc108967-cmbg20-2-0-cust86.5-4.cable.virginm.net [81.101.6.87]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 11AED2313B; Sun, 13 Dec 2020 17:20:45 +0000 (UTC) Date: Sun, 13 Dec 2020 17:20:42 +0000 From: Jonathan Cameron To: Alexandre Belloni Cc: Lars-Peter Clausen , Peter Meerwald-Stadler , linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 5/6] iio:common:ms_sensors:ms_sensors_i2c: add support for alternative PROM layout Message-ID: <20201213172042.76b2e028@archlinux> In-Reply-To: <20201209234857.1521453-6-alexandre.belloni@bootlin.com> References: <20201209234857.1521453-1-alexandre.belloni@bootlin.com> <20201209234857.1521453-6-alexandre.belloni@bootlin.com> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 10 Dec 2020 00:48:56 +0100 Alexandre Belloni wrote: > Currently, only the 112bit PROM on 7 words is supported. However the ms58xx PROM _with_ 7 words (perhaps?) > family also have devices with a 128bit PROM on 8 words. See AN520: > C-CODE EXAMPLE FOR MS56XX, MS57XX (EXCEPT ANALOG SENSOR), AND MS58XX SERIES > PRESSURE SENSORS and the various device datasheets. > > The difference is that the CRC is the 4 LSBs of word7 instead of being the > 4 MSBs of word0. > > Signed-off-by: Alexandre Belloni > --- > .../iio/common/ms_sensors/ms_sensors_i2c.c | 70 ++++++++++++++++--- > 1 file changed, 59 insertions(+), 11 deletions(-) > > diff --git a/drivers/iio/common/ms_sensors/ms_sensors_i2c.c b/drivers/iio/common/ms_sensors/ms_sensors_i2c.c > index 872f90459e2e..d97ca3e1b1d7 100644 > --- a/drivers/iio/common/ms_sensors/ms_sensors_i2c.c > +++ b/drivers/iio/common/ms_sensors/ms_sensors_i2c.c > @@ -488,21 +488,18 @@ int ms_sensors_ht_read_humidity(struct ms_ht_dev *dev_data, > EXPORT_SYMBOL(ms_sensors_ht_read_humidity); > > /** > - * ms_sensors_tp_crc_valid() - CRC check function for > + * ms_sensors_tp_crc4() - Calculate PROM CRC for > * Temperature and pressure devices. > * This function is only used when reading PROM coefficients > * > * @prom: pointer to PROM coefficients array > * > - * Return: True if CRC is ok. > + * Return: CRC. > */ > -static bool ms_sensors_tp_crc_valid(u16 *prom) > +static u8 ms_sensors_tp_crc4(u16 *prom) > { > unsigned int cnt, n_bit; > - u16 n_rem = 0x0000, crc_read = prom[0], crc = (*prom & 0xF000) >> 12; > - > - prom[MS_SENSORS_TP_PROM_WORDS_NB - 1] = 0; > - prom[0] &= 0x0FFF; /* Clear the CRC computation part */ > + u16 n_rem = 0x0000; > > for (cnt = 0; cnt < MS_SENSORS_TP_PROM_WORDS_NB * 2; cnt++) { > if (cnt % 2 == 1) > @@ -517,10 +514,55 @@ static bool ms_sensors_tp_crc_valid(u16 *prom) > n_rem <<= 1; > } > } > - n_rem >>= 12; > - prom[0] = crc_read; > > - return n_rem == crc; > + return n_rem >> 12; > +} > + > +/** > + * ms_sensors_tp_crc_valid_112() - CRC check function for > + * Temperature and pressure devices for 112bit PROM. > + * This function is only used when reading PROM coefficients > + * > + * @prom: pointer to PROM coefficients array > + * > + * Return: CRC. That's a bit confusing. Perhaps return if CRC correct Sometimes CRC is used to refer to particular bits and sometimes to the check (i.e. whether it is right). > + */ > +static bool ms_sensors_tp_crc_valid_112(u16 *prom) > +{ > + u16 w0 = prom[0], crc_read = (w0 & 0xF000) >> 12; > + u8 crc; > + > + prom[0] &= 0x0FFF; /* Clear the CRC computation part */ > + prom[MS_SENSORS_TP_PROM_WORDS_NB - 1] = 0; > + > + crc = ms_sensors_tp_crc4(prom); > + > + prom[0] = w0; > + > + return crc == crc_read; > +} > + > +/** > + * ms_sensors_tp_crc_valid_128() - CRC check function for > + * Temperature and pressure devices for 128bit PROM. > + * This function is only used when reading PROM coefficients > + * > + * @prom: pointer to PROM coefficients array > + * > + * Return: CRC. > + */ > +static bool ms_sensors_tp_crc_valid_128(u16 *prom) > +{ > + u16 w7 = prom[7], crc_read = w7 & 0x000F; > + u8 crc; > + > + prom[7] &= 0xFF00; /* Clear the CRC and LSB part */ > + > + crc = ms_sensors_tp_crc4(prom); > + > + prom[7] = w7; > + > + return crc == crc_read; > } > > /** > @@ -535,6 +577,7 @@ static bool ms_sensors_tp_crc_valid(u16 *prom) > int ms_sensors_tp_read_prom(struct ms_tp_dev *dev_data) > { > int i, ret; > + bool valid; > > for (i = 0; i < dev_data->hw->prom_len; i++) { > ret = ms_sensors_read_prom_word( > @@ -546,7 +589,12 @@ int ms_sensors_tp_read_prom(struct ms_tp_dev *dev_data) > return ret; > } > > - if (!ms_sensors_tp_crc_valid(dev_data->prom)) { > + if (dev_data->hw->prom_len == 8) > + valid = ms_sensors_tp_crc_valid_128(dev_data->prom); > + else > + valid = ms_sensors_tp_crc_valid_112(dev_data->prom); > + > + if (!valid) { > dev_err(&dev_data->client->dev, > "Calibration coefficients crc check error\n"); > return -ENODEV;