On Wed, Jun 26, 2013 at 10:51:12AM +0200, Alexandre Belloni wrote: > The low resolution ADC of the mxs is able to read an internal temperature > sensor, expose that using hwmon. > > Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx> > --- Wouldn't it make more sense to use iio-hwmon and improve it if necessary ? Guenter > .../devicetree/bindings/hwmon/mxs-cputemp.txt | 18 +++ > Documentation/hwmon/mxs-cputemp | 29 +++++ > drivers/hwmon/Kconfig | 10 ++ > drivers/hwmon/Makefile | 1 + > drivers/hwmon/mxs-cputemp.c | 132 +++++++++++++++++++++ > 5 files changed, 190 insertions(+) > create mode 100644 Documentation/devicetree/bindings/hwmon/mxs-cputemp.txt > create mode 100644 Documentation/hwmon/mxs-cputemp > create mode 100644 drivers/hwmon/mxs-cputemp.c > > diff --git a/Documentation/devicetree/bindings/hwmon/mxs-cputemp.txt b/Documentation/devicetree/bindings/hwmon/mxs-cputemp.txt > new file mode 100644 > index 0000000..7d3ae47 > --- /dev/null > +++ b/Documentation/devicetree/bindings/hwmon/mxs-cputemp.txt > @@ -0,0 +1,18 @@ > +mxs cputemp hwmon sensors > +------------------------- > + > +See: Documentation/hwmon/mxs-cputemp > + > +Required properties: > +- compatible: should be "fsl,mxs-internal-temp" > +- io-channels: should list the two adc channels needed to calculate the > + temperature > +- io-channel-names: should map the previously listed adc channels to the "min" > + and "max" value > + > +Example: > + temp { > + compatible = "fsl,mxs-internal-temp"; > + io-channels = <&lradc 8>, <&lradc 9>; > + io-channel-names = "min", "max"; > + }; > diff --git a/Documentation/hwmon/mxs-cputemp b/Documentation/hwmon/mxs-cputemp > new file mode 100644 > index 0000000..6c6201f > --- /dev/null > +++ b/Documentation/hwmon/mxs-cputemp > @@ -0,0 +1,29 @@ > +Kernel driver mxs-cputemp > +========================= > + > +Supported chips: > + * Freescale i.mx28 > + Datasheet: i.MX28 Applications Processor Reference Manual, Rev. 1, 2010 > + http://cache.freescale.com/files/dsp/doc/ref_manual/MCIMX28RM.pdf > + > +Author: Alexandre Belloni > + > +Description > +----------- > +This driver permits reading the internal die temperature sensor embedded inside > +Freescale i.mx28 SoCs. This sensor is read through two channels of the on chip > +Low-Resolution ADC. After calculation, the three-sigma error of the temperature > +sensor should be within ± 1.5% in degrees Kelvin. Additionally, the temperature > +sampling has a three-sigma sample-to-sample variation of 2 degrees Kelvin. If > +desired, this error can be removed by oversampling and averaging the temperature > +result. > + > +The formula is: > + (Channel9 – Channel8) * Gain_correction/4 > + > +As recommended by the datasheet, Gain_correction is equal to 1.012. > + > +sysfs entries > +------------- > +temp1_input Measured and corrected temperature in millidegrees Celsius > + > diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig > index 0428e8a..2daf794 100644 > --- a/drivers/hwmon/Kconfig > +++ b/drivers/hwmon/Kconfig > @@ -929,6 +929,16 @@ config SENSORS_MCP3021 > This driver can also be built as a module. If so, the module > will be called mcp3021. > > +config SENSORS_MXS_CPU > + tristate "MXS internal CPU temperature sensor" > + depends on MXS_LRADC > + help > + If you say yes here you get support for the i.mx28 internal > + temperature sensor. > + > + This driver can also be built as a module. If so, the module > + will be called mxs-cputemp > + > config SENSORS_NCT6775 > tristate "Nuvoton NCT6775F and compatibles" > depends on !PPC > diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile > index d17d3e6..366c92d 100644 > --- a/drivers/hwmon/Makefile > +++ b/drivers/hwmon/Makefile > @@ -108,6 +108,7 @@ obj-$(CONFIG_SENSORS_MAX6650) += max6650.o > obj-$(CONFIG_SENSORS_MAX6697) += max6697.o > obj-$(CONFIG_SENSORS_MC13783_ADC)+= mc13783-adc.o > obj-$(CONFIG_SENSORS_MCP3021) += mcp3021.o > +obj-$(CONFIG_SENSORS_MXS_CPU) += mxs-cputemp.o > obj-$(CONFIG_SENSORS_NCT6775) += nct6775.o > obj-$(CONFIG_SENSORS_NTC_THERMISTOR) += ntc_thermistor.o > obj-$(CONFIG_SENSORS_PC87360) += pc87360.o > diff --git a/drivers/hwmon/mxs-cputemp.c b/drivers/hwmon/mxs-cputemp.c > new file mode 100644 > index 0000000..a312fb5 > --- /dev/null > +++ b/drivers/hwmon/mxs-cputemp.c > @@ -0,0 +1,132 @@ > +/* > + * Driver for the mxs internal temperature sensor > + * > + * Copyright 2013 Free Electrons > + * > + * Licensed under the GPLv2 or later. > + */ > + > +#define DRVNAME "mxs-hwmon" > + > +#include <linux/device.h> > +#include <linux/err.h> > +#include <linux/hwmon.h> > +#include <linux/hwmon-sysfs.h> > +#include <linux/module.h> > +#include <linux/of.h> > +#include <linux/of_device.h> > +#include <linux/platform_device.h> > +#include <linux/iio/consumer.h> > + > +#define GAIN_CORRECTION 1012 > + > +/* The value we calculate from the ADCs is in Kelvins, don't forget to convert > + * it to Celsius */ > +#define VALUES_TO_MILLIC(min, max) ((max - min) * GAIN_CORRECTION / 4 - 272150) > + > +struct mxs_hwmon_data { > + struct device *hwmon_dev; > + struct iio_channel *chan_min; > + struct iio_channel *chan_max; > +}; > + > +static int mxs_hwmon_show_temp(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + int err, val_min, val_max; > + > + struct mxs_hwmon_data *data = dev_get_drvdata(dev); > + > + err = iio_read_channel_raw(data->chan_min, &val_min); > + if (err < 0) > + return err; > + > + err = iio_read_channel_raw(data->chan_max, &val_max); > + if (err < 0) > + return err; > + > + return sprintf(buf, "%u\n", VALUES_TO_MILLIC(val_min, val_max)); > +} > + > +static DEVICE_ATTR(temp1_input, S_IRUGO, mxs_hwmon_show_temp, NULL); > + > +static int mxs_hwmon_probe(struct platform_device *pdev) > +{ > + int err; > + struct mxs_hwmon_data *data; > + > + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); > + if (!data) > + return -ENOMEM; > + > + platform_set_drvdata(pdev, data); > + > + err = device_create_file(&pdev->dev, &dev_attr_temp1_input); > + if (err) > + return err; > + > + data->chan_min = iio_channel_get(&pdev->dev, "min"); > + if (IS_ERR(data->chan_min)) { > + err = PTR_ERR(data->chan_min); > + goto error_chan_min; > + } > + > + data->chan_max = iio_channel_get(&pdev->dev, "max"); > + if (IS_ERR(data->chan_max)) { > + err = PTR_ERR(data->chan_max); > + goto error_chan_max; > + } > + > + data->hwmon_dev = hwmon_device_register(&pdev->dev); > + if (IS_ERR(data->hwmon_dev)) { > + err = PTR_ERR(data->hwmon_dev); > + goto error_hwmon; > + } > + > + return 0; > + > +error_hwmon: > + iio_channel_release(data->chan_max); > +error_chan_max: > + iio_channel_release(data->chan_min); > +error_chan_min: > + device_remove_file(&pdev->dev, &dev_attr_temp1_input); > + > + return err; > +} > + > +static int mxs_hwmon_remove(struct platform_device *pdev) > +{ > + struct mxs_hwmon_data *data = platform_get_drvdata(pdev); > + > + iio_channel_release(data->chan_min); > + iio_channel_release(data->chan_max); > + hwmon_device_unregister(data->hwmon_dev); > + > + device_remove_file(&pdev->dev, &dev_attr_temp1_input); > + > + return 0; > +} > + > +static struct of_device_id mxs_hwmon_of_match[] = { > + { .compatible = "fsl,mxs-internal-temp", }, > + {} > +}; > +MODULE_DEVICE_TABLE(of, mxs_hwmon_of_match); > + > +static struct platform_driver mxs_hwmon_driver = { > + .probe = mxs_hwmon_probe, > + .remove = mxs_hwmon_remove, > + .driver = { > + .name = DRVNAME, > + .owner = THIS_MODULE, > + .of_match_table = mxs_hwmon_of_match, > + }, > +}; > + > +module_platform_driver(mxs_hwmon_driver); > + > +MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>"); > +MODULE_DESCRIPTION("Freescale i.MX28 hwmon sensor driver"); > +MODULE_LICENSE("GPL v2"); > +MODULE_ALIAS("platform:mxs-hwmon"); > -- > 1.8.1.2 > > -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html