Date:	Tue, 28 Jul 2015 08:30:14 +0200 (CEST)
From:	Peter Meerwald <pmeerw@...erw.net>
To:	Vladimir Barinov <vladimir.barinov@...entembedded.com>
cc:	Jonathan Cameron <jic23@...nel.org>,
	Hartmut Knaack <knaack.h@....de>,
	Lars-Peter Clausen <lars@...afoo.de>,
	linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
	cory.tusar@...1solutions.com
Subject: Re: [PATCH v2 1/5] iio: adc: hi8435: Holt HI-8435 threshold
 detector

On Tue, 28 Jul 2015, Vladimir Barinov wrote:

> Add Holt threshold detector driver for HI-8435 chip

comments below

some of this new ABI seems rather generic and could probably be moved to 
sysfs-bus-iio
 
> Signed-off-by: Vladimir Barinov <vladimir.barinov@...entembedded.com>
> ---
> Changes in version 2:
> - Added file sysfs-bus-iio-adc-hi8435
> - Changed naming from "discrete ADC" to "threshold detector"
> - Replaced swab16p/swab32p with be16_to_cpup/be32_to_cpup
> - Made *_show and *_store functions static
> - moved out from iio buffers to iio events
> - removed hi8436/hi8437 chips from the driver
> - moved from debounce_soft_delay/enable to debounce_interval via
>   IIO_CHAN_INFO_DEBOUNCE_TIME
> - added name extention "comparator"
> - moved threshold/hysteresis setup via generic iio event sysfs
> - added software mask/unmask channel events
> - added programming sensor outputs while in test mode via
>   IIO_CHAN_INFO_RAW
> - added channels .ext_info for programming sensing mode
> 
>  Documentation/ABI/testing/sysfs-bus-iio-adc-hi8435 |  76 +++
>  drivers/iio/adc/Kconfig                            |  11 +
>  drivers/iio/adc/Makefile                           |   1 +
>  drivers/iio/adc/hi8435.c                           | 659 +++++++++++++++++++++
>  4 files changed, 747 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-adc-hi8435
>  create mode 100644 drivers/iio/adc/hi8435.c
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-adc-hi8435 b/Documentation/ABI/testing/sysfs-bus-iio-adc-hi8435
> new file mode 100644
> index 0000000..2ff5bb3
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-bus-iio-adc-hi8435
> @@ -0,0 +1,76 @@
> +What		/sys/bus/iio/devices/iio:deviceX/in_voltageY_comparator_raw
> +Date:		July 2015
> +KernelVersion:	4.2.0
> +Contact:	source@...entembedded.com
> +Description:
> +		Read value is a voltage threshold measurement from channel Y.
> +		Could be ether 0 if sensor voltage lower then low voltage

either
is lower

> +		threshold or 1 if sensor votlage higher then high voltage

voltage is higher

> +		threshold.
> +		Write value is a programmed sensor output while in self test
> +		mode. Could be ether 0 or 1. The programmed value will be read

either

> +		back if /sys/bus/iio/devices/iio:deviceX/test_enable is set to 1

.

> +
> +What		/sys/bus/iio/devices/iio:deviceX/test_enable
> +Date:		July 2015
> +KernelVersion:	4.2.0
> +Contact:	source@...entembedded.com
> +Description:
> +		Enable/disable the HI-8435 self test mode.
> +		If enabled the in_voltageY_comparator_raw should be read back
> +		accordingly to written value to in_voltageY_comparator_raw
> +
> +What		/sys/bus/iio/devices/iio:deviceX/debounce_time
> +Date:		July 2015
> +KernelVersion:	4.2.0
> +Contact:	source@...entembedded.com
> +Description:
> +		Software debounce interval in millliseconds. If value is

milliseconds

> +		set to 0 then debouncing is disabled
> +
> +What		/sys/bus/iio/devices/iio:deviceX/in_voltageY_comparator_sensing_mode
> +Date:		July 2015
> +KernelVersion:	4.2.0
> +Contact:	source@...entembedded.com
> +Description:
> +		Program sensor type for threshold detector inputs.
> +		Could be ether "GND-Open" or "Supply-Open" modes. Y is a

either
mode

modes are all lowercase elsewhere

> +		threshold detector input channel. Channels 0..7, 8..15, 16..23
> +		and 24..31 has common sensor types.
> +
> +What		/sys/bus/iio/devices/iio:deviceX/events/in_voltageY_comparator_thresh_either_en
> +Date:		July 2015
> +KernelVersion:	4.2.0
> +Contact:	source@...entembedded.com
> +Description:
> +		Mask/unmask channel Y events
> +
> +What		/sys/bus/iio/devices/iio:deviceX/in_voltageY_comparator_thresh_falling_value
> +Date:		July 2015
> +KernelVersion:	4.2.0
> +Contact:	source@...entembedded.com
> +Description:
> +		Cahnnel Y low voltage threshold. If sensor input voltage goes lower then

Channel

> +		this value then the threshold falling event is pushed.
> +		Depending on in_voltageY_comparator_sensing_mode the low voltage threshold
> +		is separately set for "GND-Open" and "Supply-Open" modes.
> +		Channels 0..31 has common low threshold values, but could have different

have

> +		sensing_modes.
> +		The low voltage threshold range is between 2..21V.
> +		Hysteresis between low and high thresholds can not be lower then 2 and
> +		can not be odd.
> +
> +What		/sys/bus/iio/devices/iio:deviceX/in_voltageY_comparator_thresh_rising_value
> +Date:		July 2015
> +KernelVersion:	4.2.0
> +Contact:	source@...entembedded.com
> +Description:
> +		Cahnnel Y high voltage threshold. If sensor input voltage goes higher then

Channel

> +		this value then the threshold rising event is pushed.
> +		Depending on in_voltageY_comparator_sensing_mode the high voltage threshold
> +		is separately set for "GND-Open" and "Supply-Open" modes.
> +		Channels 0..31 has common high threshold values, but could have different
> +		sensing_modes.
> +		The high voltage threshold range is between 3..22V.
> +		Hysteresis between low and high thresholds can not be lower then 2 and
> +		can not be odd.
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index eb0cd89..553c91e 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -170,6 +170,17 @@ config EXYNOS_ADC
>  	  of SoCs for drivers such as the touchscreen and hwmon to use to share
>  	  this resource.
>  
> +config HI8435
> +	tristate "Holt Integrated Circuits HI-8435 threshold detector"
> +	select IIO_TRIGGERED_EVENT
> +	depends on SPI
> +	help
> +	  If you say yes here you get support for Holt Integrated Circuits
> +	  HI-8435 chip.
> +
> +	  This driver can also be built as a module. If so, the module will be
> +	  called hi8435.
> +
>  config LP8788_ADC
>  	tristate "LP8788 ADC driver"
>  	depends on MFD_LP8788
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index a096210..00f367aa 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -19,6 +19,7 @@ obj-$(CONFIG_BERLIN2_ADC) += berlin2-adc.o
>  obj-$(CONFIG_DA9150_GPADC) += da9150-gpadc.o
>  obj-$(CONFIG_CC10001_ADC) += cc10001_adc.o
>  obj-$(CONFIG_EXYNOS_ADC) += exynos_adc.o
> +obj-$(CONFIG_HI8435) += hi8435.o
>  obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
>  obj-$(CONFIG_MAX1027) += max1027.o
>  obj-$(CONFIG_MAX1363) += max1363.o
> diff --git a/drivers/iio/adc/hi8435.c b/drivers/iio/adc/hi8435.c
> new file mode 100644
> index 0000000..5739a7c
> --- /dev/null
> +++ b/drivers/iio/adc/hi8435.c
> @@ -0,0 +1,659 @@
> +/*
> + * Holt Integrated Circuits HI-8435 threshold detector driver
> + *
> + * Copyright (C) 2015 Zodiac Inflight Innovations
> + * Copyright (C) 2015 Cogent Embedded, Inc.
> + *
> + * This program is free software; you can redistribute  it and/or modify it
> + * under  the terms of  the GNU General  Public License as published by the
> + * Free Software Foundation;  either version 2 of the  License, or (at your
> + * option) any later version.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/iio/events.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/iio/trigger.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/iio/triggered_event.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/of_gpio.h>
> +#include <linux/spi/spi.h>
> +#include <linux/workqueue.h>
> +
> +#include <linux/interrupt.h>
> +
> +#define DRV_NAME "hi8435"
> +
> +/* Register offsets for HI-8435 */
> +#define HI8435_CTRL_REG			0x02
> +#define HI8435_PSEN_REG			0x04
> +#define HI8435_TMDATA_REG		0x1E
> +#define HI8435_GOCENHYS_REG		0x3A
> +#define HI8435_SOCENHYS_REG		0x3C
> +#define HI8435_SO7_0_REG		0x10
> +#define HI8435_SO15_8_REG		0x12
> +#define HI8435_SO23_16_REG		0x14
> +#define HI8435_SO31_24_REG		0x16
> +#define HI8435_SO31_0_REG		0x78
> +
> +#define HI8435_WRITE_OPCODE		0x00
> +#define HI8435_READ_OPCODE		0x80
> +
> +/* CTRL register bits */
> +#define HI8435_CTRL_TEST		0x01
> +#define HI8435_CTRL_SRST		0x02
> +
> +#define HI8435_DEBOUNCE_DELAY_MAX	1000	/* msec */
> +#define HI8435_DEBOUNCE_DELAY_DEF	100	/* msec */
> +
> +struct hi8435_priv {
> +	struct spi_device *spi;
> +	struct mutex lock;
> +	struct delayed_work work;
> +
> +	int reset_gpio;
> +	int debounce_interval; /* msec */
> +	u32 debounce_val; /* prev value to compare during software debounce */
> +
> +	unsigned long event_scan_mask; /* soft mask/unmask channels events */
> +	unsigned int event_prev_val;
> +
> +	unsigned threshold_lo[2]; /* GND-Open and Supply-Open thresholds */
> +	unsigned threshold_hi[2]; /* GND-Open and Supply-Open threshold */
> +	u8 reg_buffer[4] ____cacheline_aligned;
> +};
> +
> +static int hi8435_readb(struct hi8435_priv *priv, u8 reg, u8 *val)
> +{
> +	reg |= HI8435_READ_OPCODE;
> +	return spi_write_then_read(priv->spi, &reg, 1, val, 1);
> +}
> +
> +static int hi8435_readw(struct hi8435_priv *priv, u8 reg, u16 *val)
> +{
> +	int ret;
> +
> +	reg |= HI8435_READ_OPCODE;
> +	ret = spi_write_then_read(priv->spi, &reg, 1, val, 2);
> +	*val = be16_to_cpup(val);
> +
> +	return ret;
> +}
> +
> +static int hi8435_readl(struct hi8435_priv *priv, u8 reg, u32 *val)
> +{
> +	int ret;
> +
> +	reg |= HI8435_READ_OPCODE;
> +	ret = spi_write_then_read(priv->spi, &reg, 1, val, 4);
> +	*val = be32_to_cpup(val);
> +
> +	return ret;
> +}
> +
> +static int hi8435_writeb(struct hi8435_priv *priv, u8 reg, u8 val)
> +{
> +	priv->reg_buffer[0] = reg | HI8435_WRITE_OPCODE;
> +	priv->reg_buffer[1] = val;
> +
> +	return spi_write(priv->spi, priv->reg_buffer, 2);
> +}
> +
> +static int hi8435_writew(struct hi8435_priv *priv, u8 reg, u16 val)
> +{
> +	priv->reg_buffer[0] = reg | HI8435_WRITE_OPCODE;
> +	priv->reg_buffer[1] = (val >> 8) & 0xff;
> +	priv->reg_buffer[2] = val & 0xff;
> +
> +	return spi_write(priv->spi, priv->reg_buffer, 3);
> +}
> +
> +static ssize_t hi8435_test_enable_show(struct device *dev,
> +				       struct device_attribute *attr, char *buf)
> +{
> +	struct hi8435_priv *priv = iio_priv(dev_to_iio_dev(dev));
> +	int ret;
> +	u8 reg;
> +
> +	ret = hi8435_readb(priv, HI8435_CTRL_REG, &reg);
> +	if (ret < 0)
> +		return ret;
> +
> +	return sprintf(buf, "%d\n", reg & HI8435_CTRL_TEST);
> +}
> +
> +static ssize_t hi8435_test_enable_store(struct device *dev,
> +					struct device_attribute *attr,
> +					const char *buf, size_t len)
> +{
> +	struct hi8435_priv *priv = iio_priv(dev_to_iio_dev(dev));
> +	unsigned int val;
> +	int ret;
> +
> +	ret = kstrtouint(buf, 10, &val);
> +	if (ret)
> +		return ret;
> +
> +	hi8435_writeb(priv, HI8435_CTRL_REG, val ? HI8435_CTRL_TEST : 0);
> +
> +	return len;
> +}
> +
> +static IIO_DEVICE_ATTR(test_enable, S_IRUGO | S_IWUSR,
> +	hi8435_test_enable_show, hi8435_test_enable_store, 0);
> +
> +static struct attribute *hi8435_attributes[] = {
> +	&iio_dev_attr_test_enable.dev_attr.attr,
> +	NULL,
> +};
> +
> +static struct attribute_group hi8435_attribute_group = {
> +	.attrs = hi8435_attributes,
> +};
> +
> +static int hi8435_read_raw(struct iio_dev *idev,
> +			   const struct iio_chan_spec *chan,
> +			   int *val, int *val2, long mask)
> +{
> +	struct hi8435_priv *priv = iio_priv(idev);
> +	int ret;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		ret = hi8435_readl(priv, HI8435_SO31_0_REG, val);
> +		if (ret < 0)
> +			return ret;
> +		*val = !!(*val & BIT(chan->channel));
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_DEBOUNCE_TIME:
> +		*val = priv->debounce_interval;
> +		return IIO_VAL_INT;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int hi8435_write_raw(struct iio_dev *idev,
> +			    const struct iio_chan_spec *chan,
> +			    int val, int val2, long mask)
> +{
> +	struct hi8435_priv *priv = iio_priv(idev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		/* program sensors outputs in test mode */
> +		hi8435_writeb(priv, HI8435_TMDATA_REG, val ? 0x1 : 0x2);

no error checking

> +		return 0;
> +	case IIO_CHAN_INFO_DEBOUNCE_TIME:
> +		if (val < 0)
> +			return -EINVAL;
> +		if (val > HI8435_DEBOUNCE_DELAY_MAX)
> +			val = HI8435_DEBOUNCE_DELAY_MAX;
> +		priv->debounce_interval = val;
> +		return 0;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int hi8435_read_event_config(struct iio_dev *idev,
> +				    const struct iio_chan_spec *chan,
> +				    enum iio_event_type type,
> +				    enum iio_event_direction dir)
> +{
> +	struct hi8435_priv *priv = iio_priv(idev);
> +
> +	return !!(priv->event_scan_mask & BIT(chan->channel));
> +}
> +
> +static int hi8435_write_event_config(struct iio_dev *idev,
> +				     const struct iio_chan_spec *chan,
> +				     enum iio_event_type type,
> +				     enum iio_event_direction dir, int state)
> +{
> +	struct hi8435_priv *priv = iio_priv(idev);
> +
> +	priv->event_scan_mask &= ~BIT(chan->channel);
> +	if (state)
> +		priv->event_scan_mask |= BIT(chan->channel);
> +
> +	return 0;
> +}
> +
> +static int hi8435_read_event_value(struct iio_dev *idev,
> +				   const struct iio_chan_spec *chan,
> +				   enum iio_event_type type,
> +				   enum iio_event_direction dir,
> +				   enum iio_event_info info,
> +				   int *val, int *val2)
> +{
> +	struct hi8435_priv *priv = iio_priv(idev);
> +	int ret;
> +	u8 mode, psen;
> +	u16 reg;
> +
> +	ret = hi8435_readb(priv, HI8435_PSEN_REG, &psen);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Supply-Open or GND-Open sensing mode */
> +	mode = !!(psen & BIT(chan->channel / 8));
> +
> +	ret = hi8435_readw(priv, mode ? HI8435_SOCENHYS_REG :
> +				 HI8435_GOCENHYS_REG, &reg);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (dir == IIO_EV_DIR_FALLING)
> +		*val = ((reg & 0xff) - (reg >> 8)) / 2;
> +
> +	if (dir == IIO_EV_DIR_RISING)
> +		*val = ((reg & 0xff) + (reg >> 8)) / 2;
> +
> +	return IIO_VAL_INT;
> +}
> +
> +static int hi8435_write_event_value(struct iio_dev *idev,
> +				    const struct iio_chan_spec *chan,
> +				    enum iio_event_type type,
> +				    enum iio_event_direction dir,
> +				    enum iio_event_info info,
> +				    int val, int val2)
> +{
> +	struct hi8435_priv *priv = iio_priv(idev);
> +	int ret;
> +	u8 mode, psen;
> +	u16 reg;
> +
> +	ret = hi8435_readb(priv, HI8435_PSEN_REG, &psen);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* Supply-Open or GND-Open sensing mode */
> +	mode = !!(psen & BIT(chan->channel / 8));
> +
> +	ret = hi8435_readw(priv, mode ? HI8435_SOCENHYS_REG :
> +				 HI8435_GOCENHYS_REG, &reg);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (dir == IIO_EV_DIR_FALLING) {
> +		/* falling threshold range 2..21V, hysteresis minimum 2V */
> +		if (val < 2 || val > 21 || (val + 1) >= priv->threshold_hi[mode])
> +			return -EINVAL;
> +
> +		if (val == priv->threshold_lo[mode])
> +			return 0;
> +
> +		priv->threshold_lo[mode] = val;
> +
> +		/* hysteresis must not be odd */
> +		if ((priv->threshold_hi[mode] - priv->threshold_lo[mode]) % 2)
> +			priv->threshold_hi[mode]--;
> +	}
> +
> +	if (dir == IIO_EV_DIR_RISING) {
> +		/* rising threshold range 3..22V, hysteresis minimum 2V */
> +		if (val < 3 || val > 22 || val <= (priv->threshold_lo[mode] + 1))
> +			return -EINVAL;
> +
> +		if (val == priv->threshold_hi[mode])
> +			return 0;
> +
> +		priv->threshold_hi[mode] = val;
> +
> +		/* hysteresis must not be odd */
> +		if ((priv->threshold_hi[mode] - priv->threshold_lo[mode]) % 2)
> +			priv->threshold_lo[mode]++;
> +	}
> +
> +	/* program thresholds */
> +	mutex_lock(&priv->lock);
> +
> +	ret = hi8435_readw(priv, mode ? HI8435_SOCENHYS_REG :
> +				 HI8435_GOCENHYS_REG, &reg);
> +	if (ret < 0) {
> +		mutex_unlock(&priv->lock);
> +		return ret;
> +	}
> +
> +	/* hysteresis */
> +	reg = priv->threshold_hi[mode] - priv->threshold_lo[mode];
> +	reg <<= 8;
> +	/* threshold center */
> +	reg |= (priv->threshold_hi[mode] + priv->threshold_lo[mode]);
> +
> +	hi8435_writew(priv, mode ? HI8435_SOCENHYS_REG :
> +			    HI8435_GOCENHYS_REG, reg);
> +
> +	mutex_unlock(&priv->lock);
> +
> +	return 0;
> +}
> +
> +static const struct iio_event_spec hi8435_events[] = {
> +	{
> +		.type = IIO_EV_TYPE_THRESH,
> +		.dir = IIO_EV_DIR_RISING,
> +		.mask_separate = BIT(IIO_EV_INFO_VALUE),
> +	}, {
> +		.type = IIO_EV_TYPE_THRESH,
> +		.dir = IIO_EV_DIR_FALLING,
> +		.mask_separate = BIT(IIO_EV_INFO_VALUE),
> +	}, {
> +		.type = IIO_EV_TYPE_THRESH,
> +		.dir = IIO_EV_DIR_EITHER,
> +		.mask_separate = BIT(IIO_EV_INFO_ENABLE),
> +	},
> +};
> +
> +static int hi8435_get_sensing_mode(struct iio_dev *idev,
> +				   const struct iio_chan_spec *chan)
> +{
> +	struct hi8435_priv *priv = iio_priv(idev);
> +	int ret;
> +	u8 reg;
> +
> +	ret = hi8435_readb(priv, HI8435_PSEN_REG, &reg);
> +	if (ret < 0)
> +		return ret;
> +
> +	return !!(reg & BIT(chan->channel / 8));
> +}
> +
> +static int hi8435_set_sensing_mode(struct iio_dev *idev,
> +				   const struct iio_chan_spec *chan,
> +				   unsigned int mode)
> +{
> +	struct hi8435_priv *priv = iio_priv(idev);
> +	int ret;
> +	u8 reg;
> +
> +	mutex_lock(&priv->lock);
> +
> +	ret = hi8435_readb(priv, HI8435_PSEN_REG, &reg);
> +	if (ret < 0) {
> +		mutex_unlock(&priv->lock);
> +		return ret;
> +	}
> +
> +	reg &= ~BIT(chan->channel / 8);
> +	if (mode)
> +		reg |= BIT(chan->channel / 8);
> +
> +	hi8435_writeb(priv, HI8435_PSEN_REG, reg);
> +
> +	mutex_unlock(&priv->lock);
> +
> +	return 0;
> +}
> +
> +static const char * const hi8435_sensing_modes[] = { "GND-Open",
> +						     "Supply-Open" };
> +
> +static const struct iio_enum hi8435_sensing_mode = {
> +	.items = hi8435_sensing_modes,
> +	.num_items = ARRAY_SIZE(hi8435_sensing_modes),
> +	.get = hi8435_get_sensing_mode,
> +	.set = hi8435_set_sensing_mode,
> +};
> +
> +static const struct iio_chan_spec_ext_info hi8435_ext_info[] = {
> +	IIO_ENUM("sensing_mode", IIO_SEPARATE, &hi8435_sensing_mode),
> +	{},
> +};
> +
> +#define HI8435_VOLTAGE_CHANNEL(num)					\
> +{									\
> +	.type = IIO_VOLTAGE,						\
> +	.indexed = 1,							\
> +	.channel = num,							\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),			\
> +	.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_DEBOUNCE_TIME),	\
> +	.event_spec = hi8435_events,					\
> +	.num_event_specs = ARRAY_SIZE(hi8435_events),			\
> +	.ext_info = hi8435_ext_info,					\
> +	.extend_name = "comparator"					\
> +}
> +
> +static const struct iio_chan_spec hi8435_channels[] = {
> +	HI8435_VOLTAGE_CHANNEL(0),
> +	HI8435_VOLTAGE_CHANNEL(1),
> +	HI8435_VOLTAGE_CHANNEL(2),
> +	HI8435_VOLTAGE_CHANNEL(3),
> +	HI8435_VOLTAGE_CHANNEL(4),
> +	HI8435_VOLTAGE_CHANNEL(5),
> +	HI8435_VOLTAGE_CHANNEL(6),
> +	HI8435_VOLTAGE_CHANNEL(7),
> +	HI8435_VOLTAGE_CHANNEL(8),
> +	HI8435_VOLTAGE_CHANNEL(9),
> +	HI8435_VOLTAGE_CHANNEL(10),
> +	HI8435_VOLTAGE_CHANNEL(11),
> +	HI8435_VOLTAGE_CHANNEL(12),
> +	HI8435_VOLTAGE_CHANNEL(13),
> +	HI8435_VOLTAGE_CHANNEL(14),
> +	HI8435_VOLTAGE_CHANNEL(15),
> +	HI8435_VOLTAGE_CHANNEL(16),
> +	HI8435_VOLTAGE_CHANNEL(17),
> +	HI8435_VOLTAGE_CHANNEL(18),
> +	HI8435_VOLTAGE_CHANNEL(19),
> +	HI8435_VOLTAGE_CHANNEL(20),
> +	HI8435_VOLTAGE_CHANNEL(21),
> +	HI8435_VOLTAGE_CHANNEL(22),
> +	HI8435_VOLTAGE_CHANNEL(23),
> +	HI8435_VOLTAGE_CHANNEL(24),
> +	HI8435_VOLTAGE_CHANNEL(25),
> +	HI8435_VOLTAGE_CHANNEL(26),
> +	HI8435_VOLTAGE_CHANNEL(27),
> +	HI8435_VOLTAGE_CHANNEL(28),
> +	HI8435_VOLTAGE_CHANNEL(29),
> +	HI8435_VOLTAGE_CHANNEL(30),
> +	HI8435_VOLTAGE_CHANNEL(31),
> +	IIO_CHAN_SOFT_TIMESTAMP(32),
> +};
> +
> +static const struct iio_info hi8435_info = {
> +	.driver_module = THIS_MODULE,
> +	.attrs = &hi8435_attribute_group,
> +	.read_raw = hi8435_read_raw,
> +	.write_raw = hi8435_write_raw,
> +	.read_event_config = &hi8435_read_event_config,
> +	.write_event_config = hi8435_write_event_config,
> +	.read_event_value = &hi8435_read_event_value,
> +	.write_event_value = &hi8435_write_event_value,
> +};
> +
> +static void hi8435_iio_push_event(struct iio_dev *idev, unsigned int val)
> +{
> +	struct hi8435_priv *priv = iio_priv(idev);
> +	enum iio_event_direction dir;
> +	unsigned int i;
> +	unsigned int status = priv->event_prev_val ^ val;
> +
> +	if (!status)
> +		return;
> +
> +	for_each_set_bit(i, &priv->event_scan_mask, 32) {
> +		if (!(status & BIT(i)))
> +			continue;
> +
> +		dir = val & BIT(i) ? IIO_EV_DIR_RISING : IIO_EV_DIR_FALLING;
> +
> +		iio_push_event(idev,
> +			       IIO_UNMOD_EVENT_CODE(IIO_VOLTAGE, i,
> +						    IIO_EV_TYPE_THRESH, dir),
> +			       iio_get_time_ns());
> +	}
> +
> +	priv->event_prev_val = val;
> +}
> +
> +static void hi8435_debounce_work(struct work_struct *work)
> +{
> +	struct hi8435_priv *priv = container_of(work, struct hi8435_priv,
> +						work.work);
> +	struct iio_dev *idev = spi_get_drvdata(priv->spi);
> +	u32 val;
> +	int ret;
> +
> +	ret = hi8435_readl(priv, HI8435_SO31_0_REG, &val);
> +	if (ret < 0)
> +		return;
> +
> +	if (val == priv->debounce_val)
> +		hi8435_iio_push_event(idev, val);
> +	else
> +		dev_warn(&priv->spi->dev, "filtered by software debounce");
> +}
> +
> +static irqreturn_t hi8435_trigger_handler(int irq, void *private)
> +{
> +	struct iio_poll_func *pf = private;
> +	struct iio_dev *idev = pf->indio_dev;
> +	struct hi8435_priv *priv = iio_priv(idev);
> +	u32 val;
> +	int ret;
> +
> +	ret = hi8435_readl(priv, HI8435_SO31_0_REG, &val);
> +	if (ret < 0)
> +		goto err_read;
> +
> +	if (priv->debounce_interval) {
> +		priv->debounce_val = val;
> +		schedule_delayed_work(&priv->work,
> +				msecs_to_jiffies(priv->debounce_interval));
> +	} else {
> +		hi8435_iio_push_event(idev, val);
> +	}
> +
> +err_read:
> +	iio_trigger_notify_done(idev->trig);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static void hi8435_parse_dt(struct hi8435_priv *priv)
> +{
> +	struct device_node *np = priv->spi->dev.of_node;
> +	int ret;
> +
> +	ret = of_get_named_gpio(np, "holt,reset-gpios", 0);
> +	priv->reset_gpio = ret < 0 ? 0 : ret;
> +
> +	ret = of_property_read_u32(np, "holt,debounce-interval",
> +				   &priv->debounce_interval);
> +	if (ret)
> +		priv->debounce_interval = 0;
> +	if (priv->debounce_interval > HI8435_DEBOUNCE_DELAY_MAX)
> +		priv->debounce_interval = HI8435_DEBOUNCE_DELAY_MAX;
> +}
> +
> +static int hi8435_probe(struct spi_device *spi)
> +{
> +	struct iio_dev *idev;
> +	struct hi8435_priv *priv;
> +	int ret;
> +
> +	idev = devm_iio_device_alloc(&spi->dev, sizeof(*priv));
> +	if (!idev)
> +		return -ENOMEM;
> +
> +	priv = iio_priv(idev);
> +	priv->spi = spi;
> +
> +	if (spi->dev.of_node)
> +		hi8435_parse_dt(priv);
> +
> +	spi_set_drvdata(spi, idev);
> +	mutex_init(&priv->lock);
> +	INIT_DELAYED_WORK(&priv->work, hi8435_debounce_work);
> +
> +	idev->dev.parent	= &spi->dev;
> +	idev->name		= spi_get_device_id(spi)->name;
> +	idev->modes		= INDIO_DIRECT_MODE;
> +	idev->info		= &hi8435_info;
> +	idev->channels		= hi8435_channels;
> +	idev->num_channels	= ARRAY_SIZE(hi8435_channels);
> +
> +	if (priv->reset_gpio) {
> +		ret = devm_gpio_request(&spi->dev, priv->reset_gpio, idev->name);
> +		if (!ret) {
> +			/* chip hardware reset */
> +			gpio_direction_output(priv->reset_gpio, 0);
> +			udelay(5);
> +			gpio_direction_output(priv->reset_gpio, 1);
> +		}
> +	} else {
> +		/* chip software reset */
> +		hi8435_writeb(priv, HI8435_CTRL_REG, HI8435_CTRL_SRST);
> +		/* get out from reset state */
> +		hi8435_writeb(priv, HI8435_CTRL_REG, 0);
> +	}
> +
> +	/* unmask all events */
> +	priv->event_scan_mask = ~(0);
> +	/* initialize default thresholds */
> +	priv->threshold_lo[0] = priv->threshold_lo[1] = 2;
> +	priv->threshold_hi[0] = priv->threshold_hi[1] = 4;
> +	hi8435_writew(priv, HI8435_GOCENHYS_REG, 0x206);
> +	hi8435_writew(priv, HI8435_SOCENHYS_REG, 0x206);
> +
> +	ret = iio_triggered_event_setup(idev, NULL, hi8435_trigger_handler);
> +	if (ret)
> +		return ret;
> +
> +	ret = iio_device_register(idev);
> +	if (ret < 0) {
> +		dev_err(&spi->dev, "unable to register device\n");
> +		goto unregister_triggered_event;
> +	}
> +
> +	return 0;
> +
> +unregister_triggered_event:
> +	iio_triggered_event_cleanup(idev);
> +	return ret;
> +}
> +
> +static int hi8435_remove(struct spi_device *spi)
> +{
> +	struct iio_dev *idev = spi_get_drvdata(spi);
> +	struct hi8435_priv *priv = iio_priv(idev);
> +
> +	cancel_delayed_work_sync(&priv->work);
> +	iio_device_unregister(idev);
> +	iio_triggered_event_cleanup(idev);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id hi8435_dt_ids[] = {
> +	{ .compatible = "holt,hi8435" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, hi8435_dt_ids);
> +
> +static const struct spi_device_id hi8435_id[] = {
> +	{ "hi8435", 0},
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(spi, hi8435_id);
> +
> +static struct spi_driver hi8435_driver = {
> +	.driver	= {
> +		.name		= DRV_NAME,
> +		.of_match_table	= of_match_ptr(hi8435_dt_ids),
> +	},
> +	.probe		= hi8435_probe,
> +	.remove		= hi8435_remove,
> +	.id_table	= hi8435_id,
> +};
> +module_spi_driver(hi8435_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Vladimir Barinov");
> +MODULE_DESCRIPTION("HI-8435 threshold detector");
> 

-- 

Peter Meerwald
+43-664-2444418 (mobile)
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