Re: [PATCH v3] iio: hid: Add temperature sensor support

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On 13/02/17 09:49, Song Hongyan wrote:
> Environmental temperature sensor is a hid defined sensor,
> it measures temperature.
> 
> More information can be found in:
> http://www.usb.org/developers/hidpage/HUTRR39b.pdf
> 
> According to IIO ABI definition, IIO_TEMP data output unit is
> milli degrees Celsius. Add the unit convert from degree to milli degree.
> 
> Signed-off-by: Song Hongyan <hongyan.song@xxxxxxxxx>
Hi Song,

I'm afraid I haven't really been taking a close look at the previous
versions so a few comments inline from me that might otherwise have
come on earlier versions.

I will be looking for a reviewed-by or Ack from Srinivas on this
before taking it (mostly to reflect the effort he has put in on those
earlier reviews!)

Jonathan
> ---
>  .../iio/common/hid-sensors/hid-sensor-attributes.c |   3 +
>  drivers/iio/temperature/Kconfig                    |  14 +
>  drivers/iio/temperature/Makefile                   |   1 +
>  drivers/iio/temperature/hid-sensor-temperature.c   | 326 +++++++++++++++++++++
>  include/linux/hid-sensor-ids.h                     |   4 +
>  5 files changed, 348 insertions(+)
>  create mode 100644 drivers/iio/temperature/hid-sensor-temperature.c
> 
> diff --git a/drivers/iio/common/hid-sensors/hid-sensor-attributes.c b/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
> index 7ef94a9..68c2bb0 100644
> --- a/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
> +++ b/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
> @@ -58,6 +58,9 @@
>  
>  	{HID_USAGE_SENSOR_PRESSURE, 0, 100, 0},
>  	{HID_USAGE_SENSOR_PRESSURE, HID_USAGE_SENSOR_UNITS_PASCAL, 0, 1000000},
> +
> +	{HID_USAGE_SENSOR_TEMPERATURE, 0, 1000, 0},
> +	{HID_USAGE_SENSOR_TEMPERATURE, HID_USAGE_SENSOR_UNITS_DEGREES, 1000, 0},
>  };
>  
>  static int pow_10(unsigned power)
> diff --git a/drivers/iio/temperature/Kconfig b/drivers/iio/temperature/Kconfig
> index 5ea77a7..5f7b9f7 100644
> --- a/drivers/iio/temperature/Kconfig
> +++ b/drivers/iio/temperature/Kconfig
> @@ -19,6 +19,20 @@ config MAXIM_THERMOCOUPLE
>  	  This driver can also be built as a module. If so, the module will
>  	  be called maxim_thermocouple.
>  
> +config HID_SENSOR_TEMP
> +	tristate "HID Environmental temperature sensor"
> +	depends on HID_SENSOR_HUB
> +	select IIO_BUFFER
> +	select IIO_TRIGGERED_BUFFER
> +	select HID_SENSOR_IIO_COMMON
> +	select HID_SENSOR_IIO_TRIGGER
> +	help
> +	  Say yes here to build support for the HID SENSOR
> +	  temperature driver
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called hid-sensor-temperature.
> +
>  config MLX90614
>  	tristate "MLX90614 contact-less infrared sensor"
>  	depends on I2C
> diff --git a/drivers/iio/temperature/Makefile b/drivers/iio/temperature/Makefile
> index 78c3de0..e157eda 100644
> --- a/drivers/iio/temperature/Makefile
> +++ b/drivers/iio/temperature/Makefile
> @@ -7,3 +7,4 @@ obj-$(CONFIG_MLX90614) += mlx90614.o
>  obj-$(CONFIG_TMP006) += tmp006.o
>  obj-$(CONFIG_TSYS01) += tsys01.o
>  obj-$(CONFIG_TSYS02D) += tsys02d.o
> +obj-$(CONFIG_HID_SENSOR_TEMP)   += hid-sensor-temperature.o
> diff --git a/drivers/iio/temperature/hid-sensor-temperature.c b/drivers/iio/temperature/hid-sensor-temperature.c
> new file mode 100644
> index 0000000..84abd2d
> --- /dev/null
> +++ b/drivers/iio/temperature/hid-sensor-temperature.c
> @@ -0,0 +1,326 @@
> +/* HID Sensors Driver
> + * Copyright (c) 2017, Intel Corporation.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program.
> + *
> + */
> +#include <linux/device.h>
> +#include <linux/hid-sensor-hub.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/triggered_buffer.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include "../common/hid-sensors/hid-sensor-trigger.h"
> +
> +struct temperature_state {
> +	struct hid_sensor_common common_attributes;
> +	struct hid_sensor_hub_attribute_info temperature_attr;
> +	s32 temperature_data;
> +	int scale_pre_decml;
> +	int scale_post_decml;
> +	int scale_precision;
> +	int value_offset;
> +};
> +
> +/* Channel definitions */
> +static const struct iio_chan_spec temperature_channels[] = {
> +	{
> +		.type = IIO_TEMP,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |
> +			BIT(IIO_CHAN_INFO_SCALE) |
> +			BIT(IIO_CHAN_INFO_SAMP_FREQ) |
> +			BIT(IIO_CHAN_INFO_HYSTERESIS),
> +		.scan_index = 0,
> +	}
> +};
> +
> +/* Adjust channel real bits based on report descriptor */
> +static void temperature_adjust_channel_bit_mask(struct iio_chan_spec *channels,
> +					int channel, int size)
> +{
> +	channels[channel].scan_type.sign = 's';
> +	/* Real storage bits will change based on the report desc. */
> +	channels[channel].scan_type.realbits = size * 8;
> +	/* Maximum size of a sample to capture is s32 */
> +	channels[channel].scan_type.storagebits = sizeof(s32) * 8;
> +}
> +
> +/* Channel read_raw handler */
> +static int temperature_read_raw(struct iio_dev *indio_dev,
> +				struct iio_chan_spec const *chan,
> +				int *val, int *val2, long mask)
> +{
> +	struct temperature_state *temperature_state = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		if (chan->type == IIO_TEMP) {
> +			hid_sensor_power_state(
> +				&temperature_state->common_attributes, true);
> +			*val = sensor_hub_input_attr_get_raw_value(
> +				temperature_state->common_attributes.hsdev,
> +				HID_USAGE_SENSOR_TEMPERATURE,
> +				HID_USAGE_SENSOR_DATA_ENVIRONMENTAL_TEMPERATURE,
> +				temperature_state->temperature_attr.report_id,
> +				SENSOR_HUB_SYNC);
> +			hid_sensor_power_state(
> +					&temperature_state->common_attributes,
> +					false);
> +		}
This is an oddity.  If you get here without chan->type == IIO_TEMP
(which you can't, but your code is kind of assuming you can)
then you are returning that the data is valid without setting it to
anything.

I'd flip the logic
if (chan->type != IIO_TEMP) {
   return -EINVAL;
}
... normal code flow ...
> +		ret = IIO_VAL_INT;
There is nothing other than a return to be done after this so just
do it directly here instead.  Basic rule of thumb in kernel code is
return as early as possible when there is no unwinding to be done.
Same in all the branches of this switch statement pelase.
> +		break;
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = temperature_state->scale_pre_decml;
> +		*val2 = temperature_state->scale_post_decml;
> +		ret = temperature_state->scale_precision;
> +		break;
> +	case IIO_CHAN_INFO_OFFSET:
> +		*val = temperature_state->value_offset;
> +		ret = IIO_VAL_INT;
> +		break;
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		ret = hid_sensor_read_samp_freq_value(
> +				&temperature_state->common_attributes,
> +				val, val2);
> +		break;
> +	case IIO_CHAN_INFO_HYSTERESIS:
> +		ret = hid_sensor_read_raw_hyst_value(
> +				&temperature_state->common_attributes,
> +				val, val2);
> +		break;
> +	default:
> +		ret = -EINVAL;
> +	}
> +
> +	return ret;
> +}
> +
> +/* Channel write_raw handler */
Perhaps drop the more obvious comments as not necessarily providing
any additional info.  I don't really mind if you feel they are useful
however and want to keep them.
> +static int temperature_write_raw(struct iio_dev *indio_dev,
> +				struct iio_chan_spec const *chan,
> +				int val, int val2, long mask)
> +{
> +	struct temperature_state *temperature_state = iio_priv(indio_dev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		ret = hid_sensor_write_samp_freq_value(
> +				&temperature_state->common_attributes, val,
> +				val2);
As with the read_raw above, return directly within these statements rather than
having to bother with breaking out of the switch and then doing it.
Tidier code that way.

return hid_sensor....
> +		break;
> +	case IIO_CHAN_INFO_HYSTERESIS:
> +		ret = hid_sensor_write_raw_hyst_value(
> +				&temperature_state->common_attributes, val,
> +				val2);
> +		break;
> +	default:
> +		ret = -EINVAL;
> +	}
> +
> +	return ret;
> +}
> +
> +static const struct iio_info temperature_info = {
> +	.driver_module = THIS_MODULE,
> +	.read_raw = &temperature_read_raw,
> +	.write_raw = &temperature_write_raw,
> +};
> +
> +/* Callback handler to send event after all samples are received and captured */
> +static int temperature_proc_event(struct hid_sensor_hub_device *hsdev,
> +				unsigned int usage_id, void *pdev)
> +{
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +	struct temperature_state *temperature_state = iio_priv(indio_dev);
> +
> +	if (atomic_read(&temperature_state->common_attributes.data_ready))
> +		iio_push_to_buffers(indio_dev,
> +					&temperature_state->temperature_data);
> +	return 0;
> +}
> +
> +/* Capture samples in local storage */
> +static int temperature_capture_sample(struct hid_sensor_hub_device *hsdev,
> +				unsigned int usage_id, size_t raw_len,
> +				char *raw_data, void *pdev)
> +{
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +	struct temperature_state *temperature_state = iio_priv(indio_dev);
> +
> +	switch (usage_id) {
> +	case HID_USAGE_SENSOR_DATA_ENVIRONMENTAL_TEMPERATURE:
> +		temperature_state->temperature_data = *(s32 *)raw_data;
> +		return 0;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +/* Parse report which is specific to an usage id*/
> +static int temperature_parse_report(struct platform_device *pdev,
> +				struct hid_sensor_hub_device *hsdev,
> +				struct iio_chan_spec *channels,
> +				unsigned int usage_id,
> +				struct temperature_state *st)
> +{
> +	int ret;
> +
> +	ret = sensor_hub_input_get_attribute_info(hsdev, HID_INPUT_REPORT,
> +			usage_id,
> +			HID_USAGE_SENSOR_DATA_ENVIRONMENTAL_TEMPERATURE,
> +			&st->temperature_attr);
> +	if (ret < 0)
> +		return ret;
> +
> +	temperature_adjust_channel_bit_mask(channels, 0,
> +					st->temperature_attr.size);
> +
> +	st->scale_precision = hid_sensor_format_scale(
> +				HID_USAGE_SENSOR_TEMPERATURE,
> +				&st->temperature_attr,
> +				&st->scale_pre_decml, &st->scale_post_decml);
> +
> +	/* Set Sensitivity field ids, when there is no individual modifier */
> +	if (st->common_attributes.sensitivity.index < 0)
> +		sensor_hub_input_get_attribute_info(hsdev,
> +			HID_FEATURE_REPORT, usage_id,
> +			HID_USAGE_SENSOR_DATA_MOD_CHANGE_SENSITIVITY_ABS |
> +			HID_USAGE_SENSOR_DATA_ENVIRONMENTAL_TEMPERATURE,
> +			&st->common_attributes.sensitivity);
> +
> +	return ret;
> +}
> +
> +static struct hid_sensor_hub_callbacks temperature_callbacks = {
> +	.send_event = &temperature_proc_event,
> +	.capture_sample = &temperature_capture_sample,
> +};
> +
> +/* Function to initialize the processing for usage id */
> +static int hid_temperature_probe(struct platform_device *pdev)
> +{
> +	static const char *name = "temperature";
> +	struct iio_dev *indio_dev;
> +	struct temperature_state *temperature_state;
Maybe shorten the variable name to lead to some shorter lines later?
temp_st for example would I think convey enough meaning.

> +	struct hid_sensor_hub_device *hsdev = pdev->dev.platform_data;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&pdev->dev,
> +				sizeof(struct temperature_state));
Ever so slight preference for sizeof(*temperature_state)

> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	temperature_state = iio_priv(indio_dev);
> +	temperature_state->common_attributes.hsdev = hsdev;
> +	temperature_state->common_attributes.pdev = pdev;
> +
> +	ret = hid_sensor_parse_common_attributes(hsdev,
> +					HID_USAGE_SENSOR_TEMPERATURE,
> +					&temperature_state->common_attributes);
> +	if (ret)
> +		return ret;
> +
> +	indio_dev->channels = devm_kmemdup(&indio_dev->dev,
maybe rename as temp_chans as verbosity not adding much here.
> +					temperature_channels,
> +					sizeof(temperature_channels),
> +					GFP_KERNEL);
> +	if (!indio_dev->channels)
> +		return -ENOMEM;
> +
> +	ret = temperature_parse_report(pdev, hsdev,
> +				(struct iio_chan_spec *)indio_dev->channels,

This is casting away a const, which I don't particularly like.
I'd prefer that you used a local variable, got everthing setup as you like
and then assigned indio_dev->channels to it.  Semantically slightly nicer as
assumption is that they are const if accessed via this element of struct
iio_dev (here we obviously know we can change them but it's still not nice!)

> +				HID_USAGE_SENSOR_TEMPERATURE,
> +				temperature_state);
> +	if (ret)
> +		return ret;
> +
> +	indio_dev->num_channels = ARRAY_SIZE(temperature_channels);
> +	indio_dev->dev.parent = &pdev->dev;
> +	indio_dev->info = &temperature_info;
> +	indio_dev->name = name;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +
> +	ret = devm_iio_triggered_buffer_setup(&pdev->dev, indio_dev,
> +					&iio_pollfunc_store_time,
Oddity here as you don't actually use the timestamp...
> +					NULL, NULL);
> +	if (ret)
> +		return ret;
> +
> +	atomic_set(&temperature_state->common_attributes.data_ready, 0);
> +	ret = hid_sensor_setup_trigger(indio_dev, name,
> +				&temperature_state->common_attributes);
> +	if (ret)
> +		return ret;
> +
> +	platform_set_drvdata(pdev, indio_dev);
> +
> +	temperature_callbacks.pdev = pdev;
> +	ret = sensor_hub_register_callback(hsdev, HID_USAGE_SENSOR_TEMPERATURE,
> +					&temperature_callbacks);
> +	if (ret)
> +		goto error_remove_trigger;
> +
> +	ret = devm_iio_device_register(indio_dev->dev.parent, indio_dev);
> +	if (ret)
> +		goto error_remove_callback;
> +
> +	return ret;
> +
> +error_remove_callback:
> +	sensor_hub_remove_callback(hsdev, HID_USAGE_SENSOR_TEMPERATURE);
> +error_remove_trigger:
> +	hid_sensor_remove_trigger(&temperature_state->common_attributes);
> +	return ret;
> +}
> +
> +/* Function to deinitialize the processing for usage id */
> +static int hid_temperature_remove(struct platform_device *pdev)
> +{
> +	struct hid_sensor_hub_device *hsdev = pdev->dev.platform_data;
Is it just me that feels that for consistence there should be a
platform_get_platform_data() function?
A well, can't say it would really add anything, just my sense of
consistency kicking in ;)
Anyhow, not really anything to do with this driver review so feel
free to ignore!

> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +	struct temperature_state *temperature_state = iio_priv(indio_dev);
> +
> +	sensor_hub_remove_callback(hsdev, HID_USAGE_SENSOR_TEMPERATURE);
> +	hid_sensor_remove_trigger(&temperature_state->common_attributes);
> +
> +	return 0;
> +}
> +
> +static const struct platform_device_id hid_temperature_ids[] = {
> +	{
> +		/* Format: HID-SENSOR-usage_id_in_hex_lowercase */
> +		.name = "HID-SENSOR-200033",
> +	},
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(platform, hid_temperature_ids);
> +
> +static struct platform_driver hid_temperature_platform_driver = {
> +	.id_table = hid_temperature_ids,
> +	.driver = {
> +		.name	= KBUILD_MODNAME,
> +		.pm	= &hid_sensor_pm_ops,
> +	},
> +	.probe		= hid_temperature_probe,
> +	.remove		= hid_temperature_remove,
> +};
> +module_platform_driver(hid_temperature_platform_driver);
> +
> +MODULE_DESCRIPTION("HID Environmental temperature sensor");
> +MODULE_AUTHOR("Song Hongyan <hongyan.song@xxxxxxxxx>");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/hid-sensor-ids.h b/include/linux/hid-sensor-ids.h
> index bab8375..ecec978 100644
> --- a/include/linux/hid-sensor-ids.h
> +++ b/include/linux/hid-sensor-ids.h
> @@ -45,6 +45,10 @@
>  #define HID_USAGE_SENSOR_DATA_ATMOSPHERIC_PRESSURE              0x200430
>  #define HID_USAGE_SENSOR_ATMOSPHERIC_PRESSURE                   0x200431
>  
> +/* Tempreture (200033) */
> +#define	HID_USAGE_SENSOR_TEMPERATURE				0x200033
> +#define	HID_USAGE_SENSOR_DATA_ENVIRONMENTAL_TEMPERATURE		0x200434
> +
>  /* Gyro 3D: (200076) */
>  #define HID_USAGE_SENSOR_GYRO_3D				0x200076
>  #define HID_USAGE_SENSOR_DATA_ANGL_VELOCITY			0x200456
> 

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