Re: [PATCH v4] iio: driver for Semtech SX9500 proximity solution

[Jonathan Cameron <jic23@kernel.org>]

On 29/12/14 11:33, Vlad Dogaru wrote:
> On Fri, Dec 26, 2014 at 10:31:37AM +0000, Jonathan Cameron wrote:
>> On 22/12/14 12:41, Vlad Dogaru wrote:
>>> Supports buffering, IIO events and changing sampling frequency.
>>>
>>> Datasheet available at:
>>> http://www.semtech.com/images/datasheet/sx9500_ag.pdf
>>>
>>> Signed-off-by: Vlad Dogaru <vlad.dogaru@intel.com>
>> Please pick up any reviewed-by or acked-by tags from
>> previous versions here.
>> Hartmut gave you a reviewed-by.
> 
> Will do that in the next revision, sorry for missing it.
> 
>> Anyhow, one real issue with the unregistering of the trigger and
>> buffer stuff (buffer doesn't depend on irq being present, whereas trigger
>> does). You have it the other way around for unregister (it's correct for
>> the register).
>>
>> Otherwise a few comments inline.
>>
>> Looking pretty good.
>>
>> Jonathan
>>> ---
>>> Changes since v3:
>>>  - remove unnecessary typecast and double negation;
>>>
>>> Changes since v2:
>>>  - use GENMASK, BIT, ARRAY_SIZE macros where appropriate;
>>>  - use bool instead of int for prox_stat;
>>>  - rework sample frequency table code;
>>>  - consolidate event config sanity checks to a single condition;
>>>  - fix bug when deciding to disable proximity IRQ;
>>>  - prefer kzalloc to kmalloc;
>>>  - only cleanup trigger if it was registered (irq > 0);
>>>  - add mention for building as module in Kconfig help text;
>>>
>>> Changes since v1:
>>>  - report raw readings of the channels instead of just 0 or 1.
>>>  - add a new Kconfig section for proximity and leave the lightning sensor in its
>>>    own one.
>>>
>>>  drivers/iio/proximity/Kconfig  |  17 +
>>>  drivers/iio/proximity/Makefile |   1 +
>>>  drivers/iio/proximity/sx9500.c | 739 +++++++++++++++++++++++++++++++++++++++++
>>>  3 files changed, 757 insertions(+)
>>>  create mode 100644 drivers/iio/proximity/sx9500.c
>>>
>>> diff --git a/drivers/iio/proximity/Kconfig b/drivers/iio/proximity/Kconfig
>>> index 0c8cdf5..41a8d8f 100644
>>> --- a/drivers/iio/proximity/Kconfig
>>> +++ b/drivers/iio/proximity/Kconfig
>>> @@ -17,3 +17,20 @@ config AS3935
>>>  	  module will be called as3935
>>>  
>>>  endmenu
>>> +
>>> +menu "Proximity sensors"
>>> +
>>> +config SX9500
>>> +	tristate "SX9500 Semtech proximity sensor"
>>> +	select IIO_BUFFER
>>> +	select IIO_TRIGGERED_BUFFER
>>> +	select REGMAP_I2C
>>> +	depends on I2C
>>> +	help
>>> +	  Say Y here to build a driver for Semtech's SX9500 capacitive
>>> +	  proximity/button sensor.
>>> +
>>> +	  To compile this driver as a module, choose M here: the
>>> +	  module will be called sx9500.
>>> +
>>> +endmenu
>>> diff --git a/drivers/iio/proximity/Makefile b/drivers/iio/proximity/Makefile
>>> index 743adee..9818dc5 100644
>>> --- a/drivers/iio/proximity/Makefile
>>> +++ b/drivers/iio/proximity/Makefile
>>> @@ -4,3 +4,4 @@
>>>  
>>>  # When adding new entries keep the list in alphabetical order
>>>  obj-$(CONFIG_AS3935)		+= as3935.o
>>> +obj-$(CONFIG_SX9500)		+= sx9500.o
>>> diff --git a/drivers/iio/proximity/sx9500.c b/drivers/iio/proximity/sx9500.c
>>> new file mode 100644
>>> index 0000000..24ab48c
>>> --- /dev/null
>>> +++ b/drivers/iio/proximity/sx9500.c
>>> @@ -0,0 +1,739 @@
>>> +/*
>>> + * Copyright (c) 2014 Intel Corporation
>>> + *
>>> + * Driver for Semtech's SX9500 capacitive proximity/button solution.
>>> + * Datasheet available at
>>> + * <http://www.semtech.com/images/datasheet/sx9500.pdf>.
>>> + *
>>> + * 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 <linux/kernel.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/module.h>
>>> +#include <linux/i2c.h>
>>> +#include <linux/irq.h>
>>> +#include <linux/acpi.h>
>>> +#include <linux/gpio/consumer.h>
>>> +#include <linux/regmap.h>
>>> +
>>> +#include <linux/iio/iio.h>
>>> +#include <linux/iio/buffer.h>
>>> +#include <linux/iio/sysfs.h>
>>> +#include <linux/iio/events.h>
>>> +#include <linux/iio/trigger.h>
>>> +#include <linux/iio/triggered_buffer.h>
>>> +#include <linux/iio/trigger_consumer.h>
>>> +
>>> +#define SX9500_DRIVER_NAME		"sx9500"
>>> +#define SX9500_IRQ_NAME			"sx9500_event"
>>> +#define SX9500_GPIO_NAME		"sx9500_gpio"
>>> +
>>> +/* Register definitions. */
>>> +#define SX9500_REG_IRQ_SRC		0x00
>>> +#define SX9500_REG_STAT			0x01
>>> +#define SX9500_REG_IRQ_MSK		0x03
>>> +
>>> +#define SX9500_REG_PROX_CTRL0		0x06
>>> +#define SX9500_REG_PROX_CTRL1		0x07
>>> +#define SX9500_REG_PROX_CTRL2		0x08
>>> +#define SX9500_REG_PROX_CTRL3		0x09
>>> +#define SX9500_REG_PROX_CTRL4		0x0a
>>> +#define SX9500_REG_PROX_CTRL5		0x0b
>>> +#define SX9500_REG_PROX_CTRL6		0x0c
>>> +#define SX9500_REG_PROX_CTRL7		0x0d
>>> +#define SX9500_REG_PROX_CTRL8		0x0e
>>> +
>>> +#define SX9500_REG_SENSOR_SEL		0x20
>>> +#define SX9500_REG_USE_MSB		0x21
>>> +#define SX9500_REG_USE_LSB		0x22
>>> +#define SX9500_REG_AVG_MSB		0x23
>>> +#define SX9500_REG_AVG_LSB		0x24
>>> +#define SX9500_REG_DIFF_MSB		0x25
>>> +#define SX9500_REG_DIFF_LSB		0x26
>>> +#define SX9500_REG_OFFSET_MSB		0x27
>>> +#define SX9500_REG_OFFSET_LSB		0x28
>>> +
>>> +#define SX9500_REG_RESET		0x7f
>>> +
>>> +/* Write this to REG_RESET to do a soft reset. */
>>> +#define SX9500_SOFT_RESET		0xde
>>> +
>>> +#define SX9500_SCAN_PERIOD_MASK		GENMASK(6, 4)
>>> +#define SX9500_SCAN_PERIOD_SHIFT	4
>>> +
>>> +/*
>>> + * These serve for identifying IRQ source in the IRQ_SRC register, and
>>> + * also for masking the IRQs in the IRQ_MSK register.
>>> + */
>>> +#define SX9500_CLOSE_IRQ		BIT(6)
>>> +#define SX9500_FAR_IRQ			BIT(5)
>>> +#define SX9500_CONVDONE_IRQ		BIT(3)
>>> +
>>> +#define SX9500_PROXSTAT_SHIFT		4
>>> +
>>> +#define SX9500_NUM_CHANNELS		4
>>> +
>>> +struct sx9500_data {
>>> +	struct mutex mutex;
>>> +	struct i2c_client *client;
>>> +	struct iio_trigger *trig;
>>> +	struct regmap *regmap;
>>> +	/*
>>> +	 * Last reading of the proximity status for each channel.  We
>>> +	 * only send an event to user space when this changes.
>>> +	 */
>>> +	bool prox_stat[SX9500_NUM_CHANNELS];
>>> +	bool event_enabled[SX9500_NUM_CHANNELS];
>>> +	bool trigger_enabled;
>>> +};
>>> +
>>> +static const struct iio_event_spec sx9500_events[] = {
>>> +	{
>>> +		.type = IIO_EV_TYPE_THRESH,
>>> +		.dir = IIO_EV_DIR_EITHER,
>>> +		.mask_separate = BIT(IIO_EV_INFO_ENABLE),
>>> +	},
>>> +};
>>> +
>>> +#define SX9500_CHANNEL(idx)					\
>>> +	{							\
>>> +		.type = IIO_PROXIMITY,				\
>>> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
>>> +		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
>>> +		.indexed = 1,					\
>>> +		.channel = idx,					\
>>> +		.event_spec = sx9500_events,			\
>>> +		.num_event_specs = ARRAY_SIZE(sx9500_events),	\
>>> +		.scan_index = idx,				\
>>> +		.scan_type = {					\
>>> +			.sign = 'u',				\
>>> +			.realbits = 16,				\
>>> +			.storagebits = 16,			\
>>> +			.shift = 0,				\
>>> +		},						\
>>> +	}
>>> +
>>> +static const struct iio_chan_spec sx9500_channels[] = {
>>> +	SX9500_CHANNEL(0),
>>> +	SX9500_CHANNEL(1),
>>> +	SX9500_CHANNEL(2),
>>> +	SX9500_CHANNEL(3),
>>> +	IIO_CHAN_SOFT_TIMESTAMP(4),
>>> +};
>>> +
>>> +static const struct {
>>> +	int val;
>>> +	int val2;
>>> +} sx9500_samp_freq_table[] = {
>>> +	{33, 333333},
>>> +	{16, 666666},
>>> +	{11, 111111},
>>> +	{8, 333333},
>>> +	{6, 666666},
>>> +	{5, 0},
>>> +	{3, 333333},
>>> +	{2, 500000},
>>> +};
>>> +
>>> +static const struct regmap_range sx9500_writable_reg_ranges[] = {
>>> +	regmap_reg_range(SX9500_REG_IRQ_MSK, SX9500_REG_IRQ_MSK),
>>> +	regmap_reg_range(SX9500_REG_PROX_CTRL0, SX9500_REG_PROX_CTRL8),
>>> +	regmap_reg_range(SX9500_REG_SENSOR_SEL, SX9500_REG_SENSOR_SEL),
>>> +	regmap_reg_range(SX9500_REG_OFFSET_MSB, SX9500_REG_OFFSET_LSB),
>>> +	regmap_reg_range(SX9500_REG_RESET, SX9500_REG_RESET),
>>> +};
>>> +
>>> +static const struct regmap_access_table sx9500_writeable_regs = {
>>> +	.yes_ranges = sx9500_writable_reg_ranges,
>>> +	.n_yes_ranges = ARRAY_SIZE(sx9500_writable_reg_ranges),
>>> +};
>>> +
>>> +/*
>>> + * All allocated registers are readable, so we just list unallocated
>>> + * ones.
>>> + */
>>> +static const struct regmap_range sx9500_non_readable_reg_ranges[] = {
>>> +	regmap_reg_range(SX9500_REG_STAT + 1, SX9500_REG_STAT + 1),
>>> +	regmap_reg_range(SX9500_REG_IRQ_MSK + 1, SX9500_REG_PROX_CTRL0 - 1),
>>> +	regmap_reg_range(SX9500_REG_PROX_CTRL8 + 1, SX9500_REG_SENSOR_SEL - 1),
>>> +	regmap_reg_range(SX9500_REG_OFFSET_LSB + 1, SX9500_REG_RESET - 1),
>>> +};
>>> +
>>> +static const struct regmap_access_table sx9500_readable_regs = {
>>> +	.no_ranges = sx9500_non_readable_reg_ranges,
>>> +	.n_no_ranges = ARRAY_SIZE(sx9500_non_readable_reg_ranges),
>>> +};
>>> +
>>> +static const struct regmap_range sx9500_volatile_reg_ranges[] = {
>>> +	regmap_reg_range(SX9500_REG_IRQ_SRC, SX9500_REG_STAT),
>>> +	regmap_reg_range(SX9500_REG_USE_MSB, SX9500_REG_OFFSET_LSB),
>>> +	regmap_reg_range(SX9500_REG_RESET, SX9500_REG_RESET),
>>> +};
>>> +
>>> +static const struct regmap_access_table sx9500_volatile_regs = {
>>> +	.yes_ranges = sx9500_volatile_reg_ranges,
>>> +	.n_yes_ranges = ARRAY_SIZE(sx9500_volatile_reg_ranges),
>>> +};
>>> +
>>> +static const struct regmap_config sx9500_regmap_config = {
>>> +	.reg_bits = 8,
>>> +	.val_bits = 8,
>>> +
>>> +	.max_register = SX9500_REG_RESET,
>>> +	.cache_type = REGCACHE_RBTREE,
>>> +
>>> +	.wr_table = &sx9500_writeable_regs,
>>> +	.rd_table = &sx9500_readable_regs,
>>> +	.volatile_table = &sx9500_volatile_regs,
>>> +};
>>> +
>>> +static int sx9500_read_proximity(struct sx9500_data *data,
>>> +				 const struct iio_chan_spec *chan,
>>> +				 int *val)
>>> +{
>>> +	int ret;
>>> +	__be16 regval;
>>> +
>>> +	ret = regmap_write(data->regmap, SX9500_REG_SENSOR_SEL, chan->channel);
>>> +	if (ret < 0)
>>> +		return ret;
>>> +
>>> +	ret = regmap_bulk_read(data->regmap, SX9500_REG_USE_MSB, &regval, 2);
>>> +	if (ret < 0)
>>> +		return ret;
>>> +
>>> +	*val = 32767 - (s16)be16_to_cpu(regval);
>>> +
>>> +	return IIO_VAL_INT;
>>> +}
>>> +
>>> +static int sx9500_read_samp_freq(struct sx9500_data *data,
>>> +				 int *val, int *val2)
>>> +{
>>> +	int ret;
>>> +	unsigned int regval;
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +	ret = regmap_read(data->regmap, SX9500_REG_PROX_CTRL0, &regval);
>>> +	mutex_unlock(&data->mutex);
>>> +
>>> +	if (ret < 0)
>>> +		return ret;
>>> +
>>> +	regval = (regval & SX9500_SCAN_PERIOD_MASK) >> SX9500_SCAN_PERIOD_SHIFT;
>>> +	*val = sx9500_samp_freq_table[regval].val;
>>> +	*val2 = sx9500_samp_freq_table[regval].val2;
>>> +
>>> +	return IIO_VAL_INT_PLUS_MICRO;
>>> +}
>>> +
>>> +static int sx9500_read_raw(struct iio_dev *indio_dev,
>>> +			   const struct iio_chan_spec *chan,
>>> +			   int *val, int *val2, long mask)
>>> +{
>>> +	struct sx9500_data *data = iio_priv(indio_dev);
>>> +	int ret;
>>> +
>>> +	switch (chan->type) {
>>> +	case IIO_PROXIMITY:
>>> +		switch (mask) {
>>> +		case IIO_CHAN_INFO_RAW:
>>> +			if (iio_buffer_enabled(indio_dev))
>>> +				return -EBUSY;
>>> +			mutex_lock(&data->mutex);
>>> +			ret = sx9500_read_proximity(data, chan, val);
>>> +			mutex_unlock(&data->mutex);
>>> +			return ret;
>>> +		case IIO_CHAN_INFO_SAMP_FREQ:
>>> +			return sx9500_read_samp_freq(data, val, val2);
>>> +		default:
>>> +			return -EINVAL;
>>> +		}
>>> +	default:
>>> +		return -EINVAL;
>>> +	}
>>> +}
>>> +
>>> +static int sx9500_set_samp_freq(struct sx9500_data *data,
>>> +				int val, int val2)
>>> +{
>>> +	int i, ret;
>>> +
>>> +	for (i = 0; i < ARRAY_SIZE(sx9500_samp_freq_table); i++)
>>> +		if (val == sx9500_samp_freq_table[i].val &&
>>> +		    val2 == sx9500_samp_freq_table[i].val2)
>>> +			break;
>>> +
>>> +	if (i == ARRAY_SIZE(sx9500_samp_freq_table))
>>> +		return -EINVAL;
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +
>>> +	ret = regmap_update_bits(data->regmap, SX9500_REG_PROX_CTRL0,
>>> +				 SX9500_SCAN_PERIOD_MASK,
>>> +				 i << SX9500_SCAN_PERIOD_SHIFT);
>>> +
>>> +	mutex_unlock(&data->mutex);
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static int sx9500_write_raw(struct iio_dev *indio_dev,
>>> +			    const struct iio_chan_spec *chan,
>>> +			    int val, int val2, long mask)
>>> +{
>>> +	struct sx9500_data *data = iio_priv(indio_dev);
>>> +
>>> +	switch (chan->type) {
>>> +	case IIO_PROXIMITY:
>>> +		switch (mask) {
>>> +		case IIO_CHAN_INFO_SAMP_FREQ:
>>> +			return sx9500_set_samp_freq(data, val, val2);
>>> +		default:
>>> +			return -EINVAL;
>>> +		}
>>> +	default:
>>> +		return -EINVAL;
>>> +	}
>>> +}
>>> +
>>> +static irqreturn_t sx9500_irq_handler(int irq, void *private)
>>> +{
>>> +	struct iio_dev *indio_dev = private;
>>> +	struct sx9500_data *data = iio_priv(indio_dev);
>>> +
>>> +	if (data->trigger_enabled)
>>> +		iio_trigger_poll(data->trig);
>>> +
>>> +	/*
>>> +	 * Even if no event is enabled, we need to wake the thread to
>>> +	 * clear the interrupt state by reading SX9500_REG_IRQ_SRC.  It
>>> +	 * is not possible to do that here because regmap_read takes a
>>> +	 * mutex.
>>> +	 */
>> Hmm. Normally do that in the try_reenable callback of the trigger.
>> (pretty much what it is there for).  The point of doing that, is that if
>> we have a slow device using the trigger we should prevent the trigger
>> refiring until all are ready.  As it stands here, if we get a big delay
>> on the pollfunc (filling the buffer) the interrupt sitting above that
>> (and below this) might be masked for long enough that the 'event handling'
>> side of things here will have cleared it.  Mind you, if we are running that
>> close to the edge of being able to handle the data rates then all bets
>> are pretty much off anyway wrt not dropping samples.
>>
>> Probably best to leave it as it is, given there is no obvious solution.
> 
> Understood, I'll leave this as it is for now.
> 
>>> +	return IRQ_WAKE_THREAD;
>>> +}
>>> +
>>> +static irqreturn_t sx9500_irq_thread_handler(int irq, void *private)
>>> +{
>>> +	struct iio_dev *indio_dev = private;
>>> +	struct sx9500_data *data = iio_priv(indio_dev);
>>> +	int ret;
>>> +	unsigned int val, chan;
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +
>>> +	ret = regmap_read(data->regmap, SX9500_REG_IRQ_SRC, &val);
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev, "i2c transfer error in irq\n");
>>> +		goto out;
>>> +	}
>>> +
>>> +	if (!(val & (SX9500_CLOSE_IRQ | SX9500_FAR_IRQ)))
>>> +		goto out;
>>> +
>>> +	ret = regmap_read(data->regmap, SX9500_REG_STAT, &val);
>>> +	if (ret < 0) {
>>> +		dev_err(&data->client->dev, "i2c transfer error in irq\n");
>>> +		goto out;
>>> +	}
>>> +
>>> +	val >>= SX9500_PROXSTAT_SHIFT;
>>> +	for (chan = 0; chan < SX9500_NUM_CHANNELS; chan++) {
>>> +		int dir;
>>> +		u64 ev;
>>> +		bool new_prox = val & BIT(chan);
>>> +
>>> +		if (!data->event_enabled[chan])
>>> +			continue;
>>> +		if (new_prox == data->prox_stat[chan])
>>> +			/* No change on this channel. */
>>> +			continue;
>>> +
>>> +		dir = new_prox ? IIO_EV_DIR_FALLING :
>>> +			IIO_EV_DIR_RISING;
>>> +		ev = IIO_UNMOD_EVENT_CODE(IIO_PROXIMITY,
>>> +					  chan,
>>> +					  IIO_EV_TYPE_THRESH,
>>> +					  dir);
>>> +		iio_push_event(indio_dev, ev, iio_get_time_ns());
>>> +		data->prox_stat[chan] = new_prox;
>>> +	}
>>> +
>>> +out:
>>> +	mutex_unlock(&data->mutex);
>>> +
>>> +	return IRQ_HANDLED;
>>> +}
>>> +
>>> +static int sx9500_read_event_config(struct iio_dev *indio_dev,
>>> +				    const struct iio_chan_spec *chan,
>>> +				    enum iio_event_type type,
>>> +				    enum iio_event_direction dir)
>>> +{
>>> +	struct sx9500_data *data = iio_priv(indio_dev);
>>> +
>>> +	if (chan->type != IIO_PROXIMITY || type != IIO_EV_TYPE_THRESH ||
>>> +	    dir != IIO_EV_DIR_EITHER)
>>> +		return -EINVAL;
>>> +
>>> +	return data->event_enabled[chan->channel];
>>> +}
>>> +
>>> +static int sx9500_write_event_config(struct iio_dev *indio_dev,
>>> +				     const struct iio_chan_spec *chan,
>>> +				     enum iio_event_type type,
>>> +				     enum iio_event_direction dir,
>>> +				     int state)
>>> +{
>>> +	struct sx9500_data *data = iio_priv(indio_dev);
>>> +	int ret, i;
>>> +	bool any_active = false;
>>> +	unsigned int irqmask;
>>> +
>>> +	if (chan->type != IIO_PROXIMITY || type != IIO_EV_TYPE_THRESH ||
>>> +	    dir != IIO_EV_DIR_EITHER)
>>> +		return -EINVAL;
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +
>>> +	data->event_enabled[chan->channel] = state;
>>> +
>>> +	for (i = 0; i < SX9500_NUM_CHANNELS; i++)
>>> +		if (data->event_enabled[i]) {
>>> +			any_active = true;
>>> +			break;
>>> +		}
>>> +
>>> +	irqmask = SX9500_CLOSE_IRQ | SX9500_FAR_IRQ;
>>> +	ret = regmap_update_bits(data->regmap, SX9500_REG_IRQ_MSK,
>>> +				 irqmask, any_active ? irqmask : 0);
>> This logic would be more readable (to my mind) as.
>> if (any_active)
>>    irqmask = SX9500...
>> else
>>    irqmask = 0;
>>
>> ret = regmap_update_bits(data->regmap, SX9500_REG_IRQ_MSK,
>> 			 irqmask, irqmask);
> 
> That won't work as it is above, I think.  The third parameter of the
> call ("mask") is constant with respect to any_active.  Only the last
> parameter ("val") depends on any_active.
good point.  oops.
> 
> I'll change it to:
> 
> irqmask = SX9500_CLOSE_IRQ | SX9500_FAR_IRQ;
> 
> if (any_active)
> 	ret = regmap_update_bits(data->regmap, SX9500_REG_IRQ_MSK,
> 				 irqmask, irqmask);
> else
> 	ret = regmap_update_bits(data->regmap, SX9500_REG_IRQ_MSK,
> 				 irqmask, 0);
> 
>> Putting a trinary operator in an argument list is just uggly ;)
>>> +
>>> +	mutex_unlock(&data->mutex);
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static IIO_CONST_ATTR_SAMP_FREQ_AVAIL(
>>> +	"2.500000 3.333333 5 6.666666 8.333333 11.111111 16.666666 33.333333");
>>> +
>>> +static struct attribute *sx9500_attributes[] = {
>>> +	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
>>> +	NULL,
>>> +};
>>> +
>>> +static const struct attribute_group sx9500_attribute_group = {
>>> +	.attrs = sx9500_attributes,
>>> +};
>>> +
>>> +static const struct iio_info sx9500_info = {
>>> +	.driver_module = THIS_MODULE,
>>> +	.attrs = &sx9500_attribute_group,
>>> +	.read_raw = &sx9500_read_raw,
>>> +	.write_raw = &sx9500_write_raw,
>>> +	.read_event_config = &sx9500_read_event_config,
>>> +	.write_event_config = &sx9500_write_event_config,
>>> +};
>>> +
>>> +static int sx9500_set_trigger_state(struct iio_trigger *trig,
>>> +				    bool state)
>>> +{
>>> +	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
>>> +	struct sx9500_data *data = iio_priv(indio_dev);
>>> +	int ret;
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +
>>> +	ret = regmap_update_bits(data->regmap, SX9500_REG_IRQ_MSK,
>>> +				 SX9500_CONVDONE_IRQ,
>>> +				 state ? SX9500_CONVDONE_IRQ : 0);
>>> +	if (ret == 0)
>>> +		data->trigger_enabled = state;
>>> +
>>> +	mutex_unlock(&data->mutex);
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static const struct iio_trigger_ops sx9500_trigger_ops = {
>>> +	.set_trigger_state = sx9500_set_trigger_state,
>>> +	.owner = THIS_MODULE,
>>> +};
>>> +
>>> +static irqreturn_t sx9500_trigger_handler(int irq, void *private)
>>> +{
>>> +	struct iio_poll_func *pf = private;
>>> +	struct iio_dev *indio_dev = pf->indio_dev;
>>> +	struct sx9500_data *data = iio_priv(indio_dev);
>>> +	s16 *buf;
>>> +	int val, bit, ret, i = 0;
>>> +
>>> +	buf = kzalloc(indio_dev->scan_bytes, GFP_KERNEL);
>> Generally a bad idea to have allocations in here (they don't change
>> from scan to scan of the device channels). We have the update_scan_mode
>> callback to allow this to be done whenever the scan mode (and hence scan_bytes)
>> changes.  Mind you, this part isn't terribly fast so it doesn't matter
>> that much if you'd rather leave the allocation here for clarity.
> 
> I thought that a small allocation would be harmless (at most 12 bytes,
> including timestamp).  Still, I had forgotten about update_scan_code,
> I'll use that in the next revision.
> 
> I think it's a good idea to change the dummy driver as well, as right
> now it's also using kmalloc in a trigger handler.  I'll send an RFC for
> that.
good idea.
> 
>>> +	if (!buf) {
>>> +		dev_err(&data->client->dev,
>>> +			"failed to allocate memory in trigger handler\n");
>>> +		return IRQ_HANDLED;
>>> +	}
>>> +
>>> +	mutex_lock(&data->mutex);
>>> +
>>> +	for_each_set_bit(bit, indio_dev->buffer->scan_mask,
>>> +			 indio_dev->masklength) {
>>> +		ret = sx9500_read_proximity(data, &indio_dev->channels[bit],
>>> +					    &val);
>>> +		if (ret < 0)
>>> +			goto out;
>>> +
>>> +		buf[i++] = val;
>>> +	}
>>> +
>>> +	iio_push_to_buffers_with_timestamp(indio_dev, buf,
>>> +					   iio_get_time_ns());
>>> +
>>> +out:
>>> +	mutex_unlock(&data->mutex);
>>> +
>>> +	kfree(buf);
>>> +
>>> +	iio_trigger_notify_done(indio_dev->trig);
>>> +
>>> +	return IRQ_HANDLED;
>>> +}
>>> +
>>> +struct sx9500_reg_default {
>>> +	u8 reg;
>>> +	u8 def;
>>> +};
>>> +
>>> +static const struct sx9500_reg_default sx9500_default_regs[] = {
>>> +	{
>>> +		.reg = SX9500_REG_PROX_CTRL1,
>>> +		/* Shield enabled, small range. */
>>> +		.def = 0x43,
>>> +	},
>>> +	{
>>> +		.reg = SX9500_REG_PROX_CTRL2,
>>> +		/* x8 gain, 167kHz frequency, finest resolution. */
>>> +		.def = 0x77,
>>> +	},
>>> +	{
>>> +		.reg = SX9500_REG_PROX_CTRL3,
>>> +		/* Doze enabled, 2x scan period doze, no raw filter. */
>>> +		.def = 0x40,
>>> +	},
>>> +	{
>>> +		.reg = SX9500_REG_PROX_CTRL4,
>>> +		/* Average threshold. */
>>> +		.def = 0x30,
>>> +	},
>>> +	{
>>> +		.reg = SX9500_REG_PROX_CTRL5,
>>> +		/*
>>> +		 * Debouncer off, lowest average negative filter,
>>> +		 * highest average postive filter.
>>> +		 */
>>> +		.def = 0x0f,
>>> +	},
>>> +	{
>>> +		.reg = SX9500_REG_PROX_CTRL6,
>>> +		/* Proximity detection threshold: 280 */
>>> +		.def = 0x0e,
>>> +	},
>>> +	{
>>> +		.reg = SX9500_REG_PROX_CTRL7,
>>> +		/*
>>> +		 * No automatic compensation, compensate each pin
>>> +		 * independently, proximity hysteresis: 32, close
>>> +		 * debouncer off, far debouncer off.
>>> +		 */
>>> +		.def = 0x00,
>>> +	},
>>> +	{
>>> +		.reg = SX9500_REG_PROX_CTRL8,
>>> +		/* No stuck timeout, no periodic compensation. */
>>> +		.def = 0x00,
>>> +	},
>>> +	{
>>> +		.reg = SX9500_REG_PROX_CTRL0,
>>> +		/* Scan period: 30ms, all sensors enabled. */
>>> +		.def = 0x0f,
>>> +	},
>>> +};
>>> +
>>> +static int sx9500_init_device(struct iio_dev *indio_dev)
>>> +{
>>> +	struct sx9500_data *data = iio_priv(indio_dev);
>>> +	int ret, i;
>>> +	unsigned int val;
>>> +
>>> +	ret = regmap_write(data->regmap, SX9500_REG_IRQ_MSK, 0);
>>> +	if (ret < 0)
>>> +		return ret;
>>> +
>>> +	ret = regmap_write(data->regmap, SX9500_REG_RESET,
>>> +			   SX9500_SOFT_RESET);
>>> +	if (ret < 0)
>>> +		return ret;
>>> +
>>> +	ret = regmap_read(data->regmap, SX9500_REG_IRQ_SRC, &val);
>>> +	if (ret < 0)
>>> +		return ret;
>>> +
>>> +	for (i = 0; i < ARRAY_SIZE(sx9500_default_regs); i++) {
>>> +		ret = regmap_write(data->regmap,
>>> +				   sx9500_default_regs[i].reg,
>>> +				   sx9500_default_regs[i].def);
>>> +		if (ret < 0)
>>> +			return ret;
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int sx9500_gpio_probe(struct i2c_client *client,
>>> +			     struct sx9500_data *data)
>>> +{
>>> +	struct device *dev;
>>> +	struct gpio_desc *gpio;
>>> +	int ret;
>>> +
>>> +	if (!client)
>>> +		return -EINVAL;
>>> +
>>> +	dev = &client->dev;
>>> +
>>> +	/* data ready gpio interrupt pin */
>>> +	gpio = devm_gpiod_get_index(dev, SX9500_GPIO_NAME, 0);
>>> +	if (IS_ERR(gpio)) {
>>> +		dev_err(dev, "acpi gpio get index failed\n");
>>> +		return PTR_ERR(gpio);
>>> +	}
>>> +
>>> +	ret = gpiod_direction_input(gpio);
>>> +	if (ret)
>>> +		return ret;
>>> +
>>> +	ret = gpiod_to_irq(gpio);
>>> +
>>> +	dev_dbg(dev, "GPIO resource, no:%d irq:%d\n", desc_to_gpio(gpio), ret);
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static int sx9500_probe(struct i2c_client *client,
>>> +			const struct i2c_device_id *id)
>>> +{
>>> +	int ret;
>>> +	struct iio_dev *indio_dev;
>>> +	struct sx9500_data *data;
>>> +
>>> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
>>> +	if (indio_dev == NULL)
>>> +		return -ENOMEM;
>>> +
>>> +	data = iio_priv(indio_dev);
>>> +	data->client = client;
>>> +	mutex_init(&data->mutex);
>>> +	data->trigger_enabled = false;
>>> +
>>> +	data->regmap = devm_regmap_init_i2c(client, &sx9500_regmap_config);
>>> +	if (IS_ERR(data->regmap))
>>> +		return PTR_ERR(data->regmap);
>>> +
>>> +	sx9500_init_device(indio_dev);
>>> +
>>> +	indio_dev->dev.parent = &client->dev;
>>> +	indio_dev->name = SX9500_DRIVER_NAME;
>>> +	indio_dev->channels = sx9500_channels;
>>> +	indio_dev->num_channels = ARRAY_SIZE(sx9500_channels);
>>> +	indio_dev->info = &sx9500_info;
>>> +	indio_dev->modes = INDIO_DIRECT_MODE;
>>> +	i2c_set_clientdata(client, indio_dev);
>>> +
>>> +	if (client->irq <= 0)
>>> +		client->irq = sx9500_gpio_probe(client, data);
>>> +
>>> +	if (client->irq > 0) {
>>> +		ret = devm_request_threaded_irq(&client->dev, client->irq,
>>> +				sx9500_irq_handler, sx9500_irq_thread_handler,
>>> +				IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
>>> +				SX9500_IRQ_NAME, indio_dev);
>>> +		if (ret < 0)
>>> +			return ret;
>>> +
>>> +		data->trig = devm_iio_trigger_alloc(&client->dev,
>>> +				"%s-dev%d", indio_dev->name, indio_dev->id);
>>> +		if (!data->trig)
>>> +			return -ENOMEM;
>>> +
>>> +		data->trig->dev.parent = &client->dev;
>>> +		data->trig->ops = &sx9500_trigger_ops;
>>> +		iio_trigger_set_drvdata(data->trig, indio_dev);
>>> +
>>> +		ret = iio_trigger_register(data->trig);
>>> +		if (ret)
>>> +			return ret;
>>> +	}
>>> +
>>> +	ret = iio_triggered_buffer_setup(indio_dev, NULL,
>>> +					 sx9500_trigger_handler, NULL);
>>> +	if (ret < 0)
>>> +		goto out_trigger_unregister;
>>> +
>>> +	ret = iio_device_register(indio_dev);
>>> +	if (ret < 0)
>>> +		goto out_buffer_cleanup;
>>> +
>>> +	return 0;
>>> +
>>> +out_buffer_cleanup:
>>> +	if (client->irq > 0)
>>> +		iio_triggered_buffer_cleanup(indio_dev);
>>> +out_trigger_unregister:
>>> +	iio_trigger_unregister(data->trig);
>> Trigger registration is dependent on the irq being valid,
>> not the triggered_buffer (could perhaps use a trigger from elsewhere).
>>
>>> +
>>> +	return ret;
>>> +}
>>> +
>>> +static int sx9500_remove(struct i2c_client *client)
>>> +{
>>> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
>>> +	struct sx9500_data *data = iio_priv(indio_dev);
>>> +
>>> +	iio_device_unregister(indio_dev);
>>> +	if (client->irq > 0)
>>> +		iio_triggered_buffer_cleanup(indio_dev);
>>> +	iio_trigger_unregister(data->trig);
>> You have the wrong line protected by if (client->irq > 0)
>> It's the trigger that needs the irq, not the triggered_buffer.
> 
> Makes sense, good catch!
> 
>>
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static const struct acpi_device_id sx9500_acpi_match[] = {
>>> +	{"SSX9500", 0},
>>> +	{ },
>>> +};
>>> +MODULE_DEVICE_TABLE(acpi, sx9500_acpi_match);
>>> +
>>> +static const struct i2c_device_id sx9500_id[] = {
>>> +	{"sx9500", 0},
>>> +	{}
>>> +};
>>> +MODULE_DEVICE_TABLE(i2c, sx9500_id);
>>> +
>>> +static struct i2c_driver sx9500_driver = {
>>> +	.driver = {
>>> +		.name	= SX9500_DRIVER_NAME,
>>> +		.acpi_match_table = ACPI_PTR(sx9500_acpi_match),
>>> +	},
>>> +	.probe		= sx9500_probe,
>>> +	.remove		= sx9500_remove,
>>> +	.id_table	= sx9500_id,
>>> +};
>>> +module_i2c_driver(sx9500_driver);
>>> +
>>> +MODULE_AUTHOR("Vlad Dogaru <vlad.dogaru@intel.com>");
>>> +MODULE_DESCRIPTION("Driver for Semtech SX9500 proximity sensor");
>>> +MODULE_LICENSE("GPL v2");
>>>
>>