From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933914AbcDSTDE (ORCPT ); Tue, 19 Apr 2016 15:03:04 -0400 Received: from saturn.retrosnub.co.uk ([178.18.118.26]:38167 "EHLO saturn.retrosnub.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933880AbcDSTDB (ORCPT ); Tue, 19 Apr 2016 15:03:01 -0400 Subject: Re: [PATCH V4 2/2] thermal: generic-adc: Add ADC based thermal sensor driver To: Laxman Dewangan , robh@kernel.org, edubezval@gmail.com, rui.zhang@intel.com, mark.rutland@arm.com, pawel.moll@arm.com, ijc+devicetree@hellion.org.uk References: <1461050521-6080-1-git-send-email-ldewangan@nvidia.com> <1461050521-6080-2-git-send-email-ldewangan@nvidia.com> Cc: linux-pm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org From: Jonathan Cameron Message-ID: <571680DC.90402@kernel.org> Date: Tue, 19 Apr 2016 20:02:52 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.1 MIME-Version: 1.0 In-Reply-To: <1461050521-6080-2-git-send-email-ldewangan@nvidia.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19/04/16 08:22, Laxman Dewangan wrote: > In some of platform, thermal sensors like NCT thermistors are > connected to the one of ADC channel. The temperature is read by > reading the voltage across the sensor resistance via ADC. Lookup > table for ADC read value to temperature is referred to get > temperature. ADC is read via IIO framework. > > Add support for thermal sensor driver which read the voltage across > sensor resistance from ADC through IIO framework. > > Signed-off-by: Laxman Dewangan Acked-by: Jonathan Cameron primarily for the IIO side of things. > > --- > Changes from V1: > - Use the two dimensional lookup table for temperature vs ADC value. > - Use non devm_ for thermal zone sensor registration as there may be > race between IIO channel release and temperature read. > > Changes from V2: > - None. > > Changes from V3: > - Jonathan suggested to use the iio_channel_read_processed only. Making > changes accordingly. > --- > drivers/thermal/Kconfig | 10 ++ > drivers/thermal/Makefile | 1 + > drivers/thermal/thermal-generic-adc.c | 182 ++++++++++++++++++++++++++++++++++ > 3 files changed, 193 insertions(+) > create mode 100644 drivers/thermal/thermal-generic-adc.c > > diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig > index 594748e..d7d0136 100644 > --- a/drivers/thermal/Kconfig > +++ b/drivers/thermal/Kconfig > @@ -400,4 +400,14 @@ config QCOM_SPMI_TEMP_ALARM > real time die temperature if an ADC is present or an estimate of the > temperature based upon the over temperature stage value. > > +config GENERIC_ADC_THERMAL > + tristate "Generic ADC based thermal sensor" > + depends on IIO > + help > + This enabled a thermal sysfs driver for the temperature sensor > + which is connected to the General Purpose ADC. The ADC channel > + is read via IIO framework and the channel information is provided > + to this driver. This driver reports the temperature by reading ADC > + channel and converts it to temperature based on lookup table. > + > endif > diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile > index d64f7f7..904593a 100644 > --- a/drivers/thermal/Makefile > +++ b/drivers/thermal/Makefile > @@ -49,3 +49,4 @@ obj-$(CONFIG_ST_THERMAL) += st/ > obj-$(CONFIG_TEGRA_SOCTHERM) += tegra/ > obj-$(CONFIG_HISI_THERMAL) += hisi_thermal.o > obj-$(CONFIG_MTK_THERMAL) += mtk_thermal.o > +obj-$(CONFIG_GENERIC_ADC_THERMAL) += thermal-generic-adc.o > diff --git a/drivers/thermal/thermal-generic-adc.c b/drivers/thermal/thermal-generic-adc.c > new file mode 100644 > index 0000000..73f55d6 > --- /dev/null > +++ b/drivers/thermal/thermal-generic-adc.c > @@ -0,0 +1,182 @@ > +/* > + * Generic ADC thermal driver > + * > + * Copyright (C) 2016 NVIDIA CORPORATION. All rights reserved. > + * > + * Author: Laxman Dewangan > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + */ > +#include > +#include > +#include > +#include > +#include > +#include > + > +struct gadc_thermal_info { > + struct device *dev; > + struct thermal_zone_device *tz_dev; > + struct iio_channel *channel; > + s32 *lookup_table; > + int nlookup_table; > +}; > + > +static int gadc_thermal_adc_to_temp(struct gadc_thermal_info *gti, int val) > +{ > + int temp, adc_hi, adc_lo; > + int i; > + > + for (i = 0; i < gti->nlookup_table; i++) { > + if (val >= gti->lookup_table[2 * i + 1]) > + break; > + } > + > + if (i == 0) { > + temp = gti->lookup_table[0]; > + } else if (i >= (gti->nlookup_table - 1)) { > + temp = gti->lookup_table[2 * (gti->nlookup_table - 1)]; > + } else { > + adc_hi = gti->lookup_table[2 * i - 1]; > + adc_lo = gti->lookup_table[2 * i + 1]; > + temp = gti->lookup_table[2 * i]; > + temp -= ((val - adc_lo) * 1000) / (adc_hi - adc_lo); > + } > + > + return temp; > +} > + > +static int gadc_thermal_get_temp(void *data, int *temp) > +{ > + struct gadc_thermal_info *gti = data; > + int val; > + int ret; > + > + ret = iio_read_channel_processed(gti->channel, &val); > + if (ret < 0) { > + dev_err(gti->dev, "IIO channel read failed %d\n", ret); > + return ret; > + } > + *temp = gadc_thermal_adc_to_temp(gti, val); > + > + return 0; > +} > + > +static const struct thermal_zone_of_device_ops gadc_thermal_ops = { > + .get_temp = gadc_thermal_get_temp, > +}; > + > +static int gadc_thermal_read_linear_lookup_table(struct device *dev, > + struct gadc_thermal_info *gti) > +{ > + struct device_node *np = dev->of_node; > + int ntable; > + int ret; > + > + ntable = of_property_count_elems_of_size(np, "temperature-lookup-table", > + sizeof(u32)); > + if (ntable < 0) { > + dev_err(dev, "Lookup table is not provided\n"); > + return ntable; > + } > + > + if (ntable % 2) { > + dev_err(dev, "Pair of temperature vs ADC read value missing\n"); > + return -EINVAL; > + } > + > + gti->lookup_table = devm_kzalloc(dev, sizeof(*gti->lookup_table) * > + ntable, GFP_KERNEL); > + if (!gti->lookup_table) > + return -ENOMEM; > + > + ret = of_property_read_u32_array(np, "temperature-lookup-table", > + (u32 *)gti->lookup_table, ntable); > + if (ret < 0) { > + dev_err(dev, "Failed to read temperature lookup table: %d\n", > + ret); > + return ret; > + } > + > + gti->nlookup_table = ntable / 2; > + > + return 0; > +} > + > +static int gadc_thermal_probe(struct platform_device *pdev) > +{ > + struct gadc_thermal_info *gti; > + int ret; > + > + if (!pdev->dev.of_node) { > + dev_err(&pdev->dev, "Only DT based supported\n"); > + return -ENODEV; > + } > + > + gti = devm_kzalloc(&pdev->dev, sizeof(*gti), GFP_KERNEL); > + if (!gti) > + return -ENOMEM; > + > + ret = gadc_thermal_read_linear_lookup_table(&pdev->dev, gti); > + if (ret < 0) > + return ret; > + > + gti->dev = &pdev->dev; > + platform_set_drvdata(pdev, gti); > + > + gti->channel = iio_channel_get(&pdev->dev, "sensor-channel"); > + if (IS_ERR(gti->channel)) { > + ret = PTR_ERR(gti->channel); > + dev_err(&pdev->dev, "IIO channel not found: %d\n", ret); > + return ret; > + } > + > + gti->tz_dev = thermal_zone_of_sensor_register(&pdev->dev, 0, > + gti, &gadc_thermal_ops); > + if (IS_ERR(gti->tz_dev)) { > + ret = PTR_ERR(gti->tz_dev); > + dev_err(&pdev->dev, "Thermal zone sensor register failed: %d\n", > + ret); > + goto sensor_fail; > + } > + > + return 0; > + > +sensor_fail: > + iio_channel_release(gti->channel); > + > + return ret; > +} > + > +static int gadc_thermal_remove(struct platform_device *pdev) > +{ > + struct gadc_thermal_info *gti = platform_get_drvdata(pdev); > + > + thermal_zone_of_sensor_unregister(&pdev->dev, gti->tz_dev); > + iio_channel_release(gti->channel); > + > + return 0; > +} > + > +static const struct of_device_id of_adc_thermal_match[] = { > + { .compatible = "generic-adc-thermal", }, > + {}, > +}; > +MODULE_DEVICE_TABLE(of, of_adc_thermal_match); > + > +static struct platform_driver gadc_thermal_driver = { > + .driver = { > + .name = "generic-adc-thermal", > + .of_match_table = of_adc_thermal_match, > + }, > + .probe = gadc_thermal_probe, > + .remove = gadc_thermal_remove, > +}; > + > +module_platform_driver(gadc_thermal_driver); > + > +MODULE_AUTHOR("Laxman Dewangan "); > +MODULE_DESCRIPTION("Generic ADC thermal driver using IIO framework with DT"); > +MODULE_LICENSE("GPL v2"); >