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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 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 AD2DFC35254 for ; Sat, 8 Feb 2020 16:03:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 28436217BA for ; Sat, 8 Feb 2020 16:03:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581177814; bh=a0WCdMsCR3bSWd7XKoKfwiTcys3eZZHiMv/g/dq7LVU=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=vTh/D8/s++SYLcBy/isk+FccxLWJQdvLqRlPy8dQULR8N6qzDaQJPUmPlEzT9BXdd Ho71H69T5oEdT0oLpEh1G77zKLjthkaW7prQYgGPIG7d5WtCqD0Fshjoib8bl2Og0n hClRsc6YqGB5bUOoPSqbZ5bDARuL/j1GEFyqWXJs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727350AbgBHQDd (ORCPT ); Sat, 8 Feb 2020 11:03:33 -0500 Received: from mail.kernel.org ([198.145.29.99]:34460 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727303AbgBHQDd (ORCPT ); Sat, 8 Feb 2020 11:03:33 -0500 Received: from archlinux (cpc149474-cmbg20-2-0-cust94.5-4.cable.virginm.net [82.4.196.95]) (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 1465121775; Sat, 8 Feb 2020 16:03:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581177811; bh=a0WCdMsCR3bSWd7XKoKfwiTcys3eZZHiMv/g/dq7LVU=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=JR8ObQuSzw7x/YcUwXpMfqcH540Ca/D347mJN1OafEsiJiKVvQ/qo7j8vTXutyZvh lqNJNmboQmHcPmApGG21qo+lLVFxgkCHnN7l5m1LsFJLV9ojBC2Rl9xxj1KMQ6RhHm rNOqvMnowZXQWGAsk+IpePuAlyrtjmG9/SJW9vKw= Date: Sat, 8 Feb 2020 16:03:27 +0000 From: Jonathan Cameron To: Olivier Moysan Cc: , , , , , , , , , Subject: Re: [PATCH 2/4] iio: adc: sd modulator: add scale support Message-ID: <20200208160327.334da020@archlinux> In-Reply-To: <20200204101008.11411-3-olivier.moysan@st.com> References: <20200204101008.11411-1-olivier.moysan@st.com> <20200204101008.11411-3-olivier.moysan@st.com> X-Mailer: Claws Mail 3.17.4 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-iio-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org On Tue, 4 Feb 2020 11:10:06 +0100 Olivier Moysan wrote: > Add scale support to sigma delta modulator. > > Signed-off-by: Olivier Moysan I note below that there are probably some complexities around whether vref is used as you have it here or not. A few other bits inline around a race condition introduced in probe / remove. Thanks, Jonathan > --- > drivers/iio/adc/sd_adc_modulator.c | 108 ++++++++++++++++++++++++++--- > 1 file changed, 100 insertions(+), 8 deletions(-) > > diff --git a/drivers/iio/adc/sd_adc_modulator.c b/drivers/iio/adc/sd_adc_modulator.c > index 560d8c7d9d86..a83f35832050 100644 > --- a/drivers/iio/adc/sd_adc_modulator.c > +++ b/drivers/iio/adc/sd_adc_modulator.c > @@ -10,8 +10,7 @@ > #include > #include > #include > - > -static const struct iio_info iio_sd_mod_iio_info; > +#include > > static const struct iio_chan_spec iio_sd_mod_ch = { > .type = IIO_VOLTAGE, > @@ -21,34 +20,126 @@ static const struct iio_chan_spec iio_sd_mod_ch = { > .realbits = 1, > .shift = 0, > }, > + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), This relies on generic sigma delta modulators using an external vref. They might have an internal always on regulator... I would suggest we only support scale for devices with explicitly defined compatibles where we can know what regulators are used etc. For many devices, there will be a single powersupply called vdd-supply or similar in DT. It may also provide a reference voltage. > +}; > + > +static const struct iio_chan_spec iio_sd_mod_ch_ads = { > + .type = IIO_VOLTAGE, > + .indexed = 1, > + .scan_type = { > + .sign = 'u', > + .realbits = 1, > + .shift = 0, > + }, > + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), > + .differential = 1, > +}; > + > +struct iio_sd_mod_priv { > + struct regulator *vref; > + int vref_mv; > +}; > + > +static int iio_sd_mod_read_raw(struct iio_dev *indio_dev, > + struct iio_chan_spec const *chan, int *val, > + int *val2, long mask) > +{ > + struct iio_sd_mod_priv *priv = iio_priv(indio_dev); > + > + switch (mask) { > + case IIO_CHAN_INFO_SCALE: > + *val = priv->vref_mv; > + *val2 = chan->scan_type.realbits; > + return IIO_VAL_INT; > + } > + > + return -EINVAL; > +} > + > +static const struct iio_info iio_sd_mod_iio_info = { > + .read_raw = iio_sd_mod_read_raw, > }; > > static int iio_sd_mod_probe(struct platform_device *pdev) > { > struct device *dev = &pdev->dev; > + struct iio_sd_mod_priv *priv; > struct iio_dev *iio; > + int ret; > > - iio = devm_iio_device_alloc(dev, 0); > + iio = devm_iio_device_alloc(dev, sizeof(*priv)); > if (!iio) > return -ENOMEM; > > + iio->channels = (const struct iio_chan_spec *) > + of_device_get_match_data(&pdev->dev); > + > + priv = iio_priv(iio); > + > iio->dev.parent = dev; > iio->dev.of_node = dev->of_node; > iio->name = dev_name(dev); > iio->info = &iio_sd_mod_iio_info; > iio->modes = INDIO_BUFFER_HARDWARE; > - > iio->num_channels = 1; > - iio->channels = &iio_sd_mod_ch; > > platform_set_drvdata(pdev, iio); > > - return devm_iio_device_register(&pdev->dev, iio); > + priv->vref = devm_regulator_get_optional(dev, "vref"); > + if (IS_ERR(priv->vref)) { > + ret = PTR_ERR(priv->vref); > + if (ret != -ENODEV) { > + if (ret != -EPROBE_DEFER) > + dev_err(dev, "vref get failed, %d\n", ret); > + return ret; > + } > + } > + > + if (!IS_ERR(priv->vref)) { > + ret = regulator_enable(priv->vref); > + if (ret < 0) { > + dev_err(dev, "vref enable failed %d\n", ret); > + return ret; > + } > + > + ret = regulator_get_voltage(priv->vref); > + if (ret < 0) { > + dev_err(dev, "vref get failed, %d\n", ret); > + goto err_regulator_disable; > + } > + > + priv->vref_mv = ret / 1000; > + dev_dbg(dev, "vref+=%dmV\n", priv->vref_mv); > + } > + > + ret = devm_iio_device_register(&pdev->dev, iio); This exposes the userspace and in kernel interfaces. Those are partly dependent on the regulator enable you have above. Using devm_ version fo this interface leaves you with a race in remove. The regulator is disabled before you have remove the interfaces that will only work if we assume it is still on. Hence, you should either use devm_add_action_or_reset magic to ensure we still do everything in the right order, or do it manually by using iio_device_register and iio_device_unregister. > + if (ret < 0) { > + dev_err(dev, "Failed to register sd-modulator, %d\n", ret); > + goto err_regulator_disable; > + } > + > + return 0; > + > +err_regulator_disable: > + regulator_disable(priv->vref); > + > + return ret; > +} > + > +static int iio_sd_mod_remove(struct platform_device *pdev) > +{ > + struct iio_dev *indio_dev = platform_get_drvdata(pdev); > + struct iio_sd_mod_priv *priv = iio_priv(indio_dev); > + > + if (priv->vref) > + return regulator_disable(priv->vref); > + > + return 0; > } > > static const struct of_device_id sd_adc_of_match[] = { > - { .compatible = "sd-modulator" }, > - { .compatible = "ads1201" }, > + { .compatible = "sd-modulator", .data = &iio_sd_mod_ch }, > + { .compatible = "ads1201", .data = &iio_sd_mod_ch_ads }, > { } > }; > MODULE_DEVICE_TABLE(of, sd_adc_of_match); > @@ -59,6 +150,7 @@ static struct platform_driver iio_sd_mod_adc = { > .of_match_table = of_match_ptr(sd_adc_of_match), > }, > .probe = iio_sd_mod_probe, > + .remove = iio_sd_mod_remove, > }; > > module_platform_driver(iio_sd_mod_adc);