Message-ID: <20200906155949.6b5fa32b@archlinux>
Date:   Sun, 6 Sep 2020 15:59:49 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Nishant Malpani <nish.malpani25@...il.com>
Cc:     robh+dt@...nel.org, dragos.bogdan@...log.com,
        darius.berghe@...log.com, linux-kernel@...r.kernel.org,
        linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
        andy.shevchenko@...il.com
Subject: Re: [PATCH v2 1/3] iio: gyro: adxrs290: Add triggered buffer
 support

On Thu,  3 Sep 2020 18:39:48 +0530
Nishant Malpani <nish.malpani25@...il.com> wrote:

> Provide a way for continuous data capture by setting up buffer support. The
> data ready signal exposed at the SYNC pin of the ADXRS290 is exploited as
> a hardware interrupt which triggers to fill the buffer.
> 
> Triggered buffer setup was tested with both hardware trigger (DATA_RDY) and
> software triggers (sysfs-trig & hrtimer).
> 
> Signed-off-by: Nishant Malpani <nish.malpani25@...il.com>
Hi Nishant,

A few additional comments

Jonathan

> ---
> 
> Changes in v2:
> 
>   - In adxrs290_set_mode(), move 'if' block outside the locked section
>   - use break statement for error handling instead of goto labels in
>     switch-case blocks
>   - remove outer parentheses when conditional ternary operator is used
>   - use dev_err_probe() saving a few lines of code
>   - re-align 'buffer' variable name in 'struct adxrs290_state'
>   - don't return errors in 'try_reenable' callback
>   - use 'st->spi' inline in 'adxrs290_trigger_handler'
>   - unnecessary to mention default 'shift' (= 0) in
>     iio_chan_spec.scan_type
>   - bring in consistent wrapping of parameters while staying under
>     the advised 80 chars line limit
> ---
>  drivers/iio/gyro/Kconfig    |   2 +
>  drivers/iio/gyro/adxrs290.c | 265 ++++++++++++++++++++++++++++++++++--
>  2 files changed, 253 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/iio/gyro/Kconfig b/drivers/iio/gyro/Kconfig
> index 024a34139875..5824f2edf975 100644
> --- a/drivers/iio/gyro/Kconfig
> +++ b/drivers/iio/gyro/Kconfig
> @@ -44,6 +44,8 @@ config ADIS16260
>  config ADXRS290
>  	tristate "Analog Devices ADXRS290 Dual-Axis MEMS Gyroscope SPI driver"
>  	depends on SPI
> +	select IIO_BUFFER
> +	select IIO_TRIGGERED_BUFFER
>  	help
>  	  Say yes here to build support for Analog Devices ADXRS290 programmable
>  	  digital output gyroscope.
> diff --git a/drivers/iio/gyro/adxrs290.c b/drivers/iio/gyro/adxrs290.c
> index ff989536d2fb..4099b8917d3e 100644
> --- a/drivers/iio/gyro/adxrs290.c
> +++ b/drivers/iio/gyro/adxrs290.c
> @@ -13,8 +13,12 @@
>  #include <linux/module.h>
>  #include <linux/spi/spi.h>
>  
> +#include <linux/iio/buffer.h>
>  #include <linux/iio/iio.h>
>  #include <linux/iio/sysfs.h>
> +#include <linux/iio/trigger.h>
> +#include <linux/iio/triggered_buffer.h>
> +#include <linux/iio/trigger_consumer.h>
>  
>  #define ADXRS290_ADI_ID		0xAD
>  #define ADXRS290_MEMS_ID	0x1D
> @@ -35,7 +39,9 @@
>  #define ADXRS290_READ		BIT(7)
>  #define ADXRS290_TSM		BIT(0)
>  #define ADXRS290_MEASUREMENT	BIT(1)
> -#define ADXRS290_SYNC		GENMASK(1, 0)
> +#define ADXRS290_DATA_RDY_OUT	BIT(0)
> +#define ADXRS290_SYNC_MASK	GENMASK(1, 0)
> +#define ADXRS290_SYNC(x)	FIELD_PREP(ADXRS290_SYNC_MASK, x)
>  #define ADXRS290_LPF_MASK	GENMASK(2, 0)
>  #define ADXRS290_LPF(x)		FIELD_PREP(ADXRS290_LPF_MASK, x)
>  #define ADXRS290_HPF_MASK	GENMASK(7, 4)
> @@ -50,6 +56,13 @@ enum adxrs290_mode {
>  	ADXRS290_MODE_MEASUREMENT,
>  };
>  
> +enum adxrs290_scan_index {
> +	ADXRS290_IDX_X,
> +	ADXRS290_IDX_Y,
> +	ADXRS290_IDX_TEMP,
> +	ADXRS290_IDX_TS,
> +};
> +
>  struct adxrs290_state {
>  	struct spi_device	*spi;
>  	/* Serialize reads and their subsequent processing */
> @@ -57,6 +70,12 @@ struct adxrs290_state {
>  	enum adxrs290_mode	mode;
>  	unsigned int		lpf_3db_freq_idx;
>  	unsigned int		hpf_3db_freq_idx;
> +	struct iio_trigger      *dready_trig;
> +	/* Ensure correct alignment of timestamp when present */
> +	struct {
> +		s16 channels[3];
> +		s64 ts __aligned(8);
> +	} buffer;
>  };
>  
>  /*
> @@ -192,6 +211,52 @@ static int adxrs290_set_filter_freq(struct iio_dev *indio_dev,
>  	return adxrs290_spi_write_reg(st->spi, ADXRS290_REG_FILTER, val);
>  }
>  
> +static int adxrs290_set_mode(struct iio_dev *indio_dev, enum adxrs290_mode mode)
> +{
> +	struct adxrs290_state *st = iio_priv(indio_dev);
> +	int val, ret;
> +
> +	if (st->mode == mode) {
> +		ret = 0;
> +		goto done;
> +	}
> +
> +	mutex_lock(&st->lock);
> +
> +	ret = spi_w8r8(st->spi, ADXRS290_READ_REG(ADXRS290_REG_POWER_CTL));
> +	if (ret < 0)
> +		goto done;
> +
> +	val = ret;
> +
> +	switch (mode) {
> +	case ADXRS290_MODE_STANDBY:
> +		val &= ~ADXRS290_MEASUREMENT;
> +		break;
> +	case ADXRS290_MODE_MEASUREMENT:
> +		val |= ADXRS290_MEASUREMENT;
> +		break;
> +	default:
> +		ret = -EINVAL;
> +		goto done;
> +	}
> +
> +	ret = adxrs290_spi_write_reg(st->spi,
> +				     ADXRS290_REG_POWER_CTL,
> +				     val);
> +	if (ret < 0) {
> +		dev_err(&st->spi->dev, "unable to set mode: %d\n", ret);
> +		goto done;
> +	}
> +
> +	/* update cached mode */
> +	st->mode = mode;
> +
> +done:
> +	mutex_unlock(&st->lock);
> +	return ret;
> +}
> +
>  static int adxrs290_initial_setup(struct iio_dev *indio_dev)
>  {
>  	struct adxrs290_state *st = iio_priv(indio_dev);
> @@ -203,6 +268,13 @@ static int adxrs290_initial_setup(struct iio_dev *indio_dev)
>  				      ADXRS290_MEASUREMENT | ADXRS290_TSM);
>  }
>  
> +static void adxrs290_chip_off_action(void *data)
> +{
> +	struct iio_dev *indio_dev = data;
> +
> +	adxrs290_set_mode(indio_dev, ADXRS290_MODE_STANDBY);
> +}
> +
>  static int adxrs290_read_raw(struct iio_dev *indio_dev,
>  			     struct iio_chan_spec const *chan,
>  			     int *val,
> @@ -215,24 +287,34 @@ static int adxrs290_read_raw(struct iio_dev *indio_dev,
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_RAW:
> +		ret = iio_device_claim_direct_mode(indio_dev);
> +		if (ret)
> +			return ret;
> +
>  		switch (chan->type) {
>  		case IIO_ANGL_VEL:
>  			ret = adxrs290_get_rate_data(indio_dev,
>  						     ADXRS290_READ_REG(chan->address),
>  						     val);
>  			if (ret < 0)
> -				return ret;
> +				break;
>  
> -			return IIO_VAL_INT;
> +			ret = IIO_VAL_INT;
> +			break;
>  		case IIO_TEMP:
>  			ret = adxrs290_get_temp_data(indio_dev, val);
>  			if (ret < 0)
> -				return ret;
> +				break;
>  
> -			return IIO_VAL_INT;
> +			ret = IIO_VAL_INT;
> +			break;
>  		default:
> -			return -EINVAL;
> +			ret = -EINVAL;
> +			break;
>  		}
> +
> +		iio_device_release_direct_mode(indio_dev);
> +		return ret;
>  	case IIO_CHAN_INFO_SCALE:
>  		switch (chan->type) {
>  		case IIO_ANGL_VEL:
> @@ -279,34 +361,52 @@ static int adxrs290_write_raw(struct iio_dev *indio_dev,
>  			      long mask)
>  {
>  	struct adxrs290_state *st = iio_priv(indio_dev);
> -	int lpf_idx, hpf_idx;
> +	int ret, lpf_idx, hpf_idx;
> +
> +	ret = iio_device_claim_direct_mode(indio_dev);
> +	if (ret)
> +		return ret;
>  
>  	switch (mask) {
>  	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
>  		lpf_idx = adxrs290_find_match(adxrs290_lpf_3db_freq_hz_table,
>  					      ARRAY_SIZE(adxrs290_lpf_3db_freq_hz_table),
>  					      val, val2);
> -		if (lpf_idx < 0)
> -			return -EINVAL;
> +		if (lpf_idx < 0) {
> +			ret = -EINVAL;
> +			break;
> +		}
> +
>  		/* caching the updated state of the low-pass filter */
>  		st->lpf_3db_freq_idx = lpf_idx;
>  		/* retrieving the current state of the high-pass filter */
>  		hpf_idx = st->hpf_3db_freq_idx;
> -		return adxrs290_set_filter_freq(indio_dev, lpf_idx, hpf_idx);
> +		ret = adxrs290_set_filter_freq(indio_dev, lpf_idx, hpf_idx);
> +		break;
> +
>  	case IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY:
>  		hpf_idx = adxrs290_find_match(adxrs290_hpf_3db_freq_hz_table,
>  					      ARRAY_SIZE(adxrs290_hpf_3db_freq_hz_table),
>  					      val, val2);
> -		if (hpf_idx < 0)
> -			return -EINVAL;
> +		if (hpf_idx < 0) {
> +			ret = -EINVAL;
> +			break;
> +		}
> +
>  		/* caching the updated state of the high-pass filter */
>  		st->hpf_3db_freq_idx = hpf_idx;
>  		/* retrieving the current state of the low-pass filter */
>  		lpf_idx = st->lpf_3db_freq_idx;
> -		return adxrs290_set_filter_freq(indio_dev, lpf_idx, hpf_idx);
> +		ret = adxrs290_set_filter_freq(indio_dev, lpf_idx, hpf_idx);
> +		break;
> +
> +	default:
> +		ret = -EINVAL;
> +		break;
>  	}
>  
> -	return -EINVAL;
> +	iio_device_release_direct_mode(indio_dev);
> +	return ret;
>  }
>  
>  static int adxrs290_read_avail(struct iio_dev *indio_dev,
> @@ -334,6 +434,69 @@ static int adxrs290_read_avail(struct iio_dev *indio_dev,
>  	}
>  }
>  
> +static int adxrs290_data_rdy_trigger_set_state(struct iio_trigger *trig, bool state)
> +{
> +	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
> +	struct adxrs290_state *st = iio_priv(indio_dev);
> +	int ret;
> +	u8 val;
> +
> +	val = state ? ADXRS290_SYNC(ADXRS290_DATA_RDY_OUT) : 0;
> +
> +	ret = adxrs290_spi_write_reg(st->spi, ADXRS290_REG_DATA_RDY, val);
> +	if (ret < 0)
> +		dev_err(&st->spi->dev, "failed to start data ready interrupt\n");
> +
> +	return ret;
> +}
> +
> +static int adxrs290_reset_trig(struct iio_trigger *trig)
> +{
> +	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
> +	int val;
> +
> +	/*
> +	 * Data ready interrupt is reset after a read of the data registers.
> +	 * Here, we only read the 16b DATAY registers as that marks the end of
> +	 * a read of the data registers and initiates a reset for the interrupt line.
> +	 */
> +	adxrs290_get_rate_data(indio_dev, ADXRS290_READ_REG(ADXRS290_REG_DATAY0), &val);
> +
> +	return 0;
> +}
> +
> +static const struct iio_trigger_ops adxrs290_trigger_ops = {
> +	.set_trigger_state = &adxrs290_data_rdy_trigger_set_state,
> +	.validate_device = &iio_trigger_validate_own_device,
> +	.try_reenable = &adxrs290_reset_trig,
> +};
> +
> +static irqreturn_t adxrs290_trigger_handler(int irq, void *p)
> +{
> +	struct iio_poll_func *pf = p;
> +	struct iio_dev *indio_dev = pf->indio_dev;
> +	struct adxrs290_state *st = iio_priv(indio_dev);
> +	u8 tx = ADXRS290_READ_REG(ADXRS290_REG_DATAX0);
> +	int ret;
> +
> +	mutex_lock(&st->lock);
> +
> +	/* exercise a bulk data capture starting from reg DATAX0... */
> +	ret = spi_write_then_read(st->spi, &tx, sizeof(tx), st->buffer.channels,
> +				  sizeof(st->buffer.channels));
> +	if (ret < 0)
> +		goto done;
> +
> +	iio_push_to_buffers_with_timestamp(indio_dev, &st->buffer,
> +					   pf->timestamp);
> +
> +done:
> +	mutex_unlock(&st->lock);
> +	iio_trigger_notify_done(indio_dev->trig);
> +
> +	return IRQ_HANDLED;
> +}
> +
>  #define ADXRS290_ANGL_VEL_CHANNEL(reg, axis) {				\
>  	.type = IIO_ANGL_VEL,						\
>  	.address = reg,							\
> @@ -346,6 +509,13 @@ static int adxrs290_read_avail(struct iio_dev *indio_dev,
>  	.info_mask_shared_by_type_available =				\
>  	BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY) |		\
>  	BIT(IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY),		\
> +	.scan_index = ADXRS290_IDX_##axis,				\
> +	.scan_type = {                                                  \
> +		.sign = 's',                                            \
> +		.realbits = 16,                                         \
> +		.storagebits = 16,                                      \
> +		.endianness = IIO_LE,					\
> +	},                                                              \
>  }
>  
>  static const struct iio_chan_spec adxrs290_channels[] = {
> @@ -356,7 +526,20 @@ static const struct iio_chan_spec adxrs290_channels[] = {
>  		.address = ADXRS290_REG_TEMP0,
>  		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
>  		BIT(IIO_CHAN_INFO_SCALE),
> +		.scan_index = ADXRS290_IDX_TEMP,
> +		.scan_type = {
> +			.sign = 's',
> +			.realbits = 12,
> +			.storagebits = 16,
> +			.endianness = IIO_LE,
> +		},
>  	},
> +	IIO_CHAN_SOFT_TIMESTAMP(ADXRS290_IDX_TS),
> +};
> +
> +static const unsigned long adxrs290_avail_scan_masks[] = {
> +	BIT(ADXRS290_IDX_X) | BIT(ADXRS290_IDX_Y) | BIT(ADXRS290_IDX_TEMP),
> +	0
>  };
>  
>  static const struct iio_info adxrs290_info = {
> @@ -365,6 +548,43 @@ static const struct iio_info adxrs290_info = {
>  	.read_avail = &adxrs290_read_avail,
>  };
>  
> +static int adxrs290_probe_trigger(struct iio_dev *indio_dev)
> +{
> +	struct adxrs290_state *st = iio_priv(indio_dev);
> +	int ret;
> +
> +	if (!st->spi->irq) {
> +		dev_info(&st->spi->dev, "no irq, using polling\n");
> +		return 0;
> +	}
> +
> +	st->dready_trig = devm_iio_trigger_alloc(&st->spi->dev, "%s-dev%d",
> +						 indio_dev->name,
> +						 indio_dev->id);
> +	if (!st->dready_trig)
> +		return -ENOMEM;
> +
> +	st->dready_trig->dev.parent = &st->spi->dev;
> +	st->dready_trig->ops = &adxrs290_trigger_ops;
> +	iio_trigger_set_drvdata(st->dready_trig, indio_dev);
> +
> +	ret = devm_request_irq(&st->spi->dev, st->spi->irq,
> +			       &iio_trigger_generic_data_rdy_poll,
> +			       IRQF_ONESHOT, "adxrs290_irq", st->dready_trig);
> +	if (ret < 0)
> +		return dev_err_probe(&st->spi->dev, ret,
> +				     "request irq %d failed\n", st->spi->irq);
> +
> +	ret = devm_iio_trigger_register(&st->spi->dev, st->dready_trig);
> +	if (ret)
> +		return dev_err_probe(&st->spi->dev, ret,

Only use dev_err_probe for calls that are requesting hardware resources
that may not yet be available.  The purpose is to handle deferred probing
neatly.  Here coming back later is unlikely to help as nothing will have
changed.

> +				     "iio trigger register failed\n");
> +
> +	indio_dev->trig = iio_trigger_get(st->dready_trig);
> +
> +	return 0;
> +}
> +
>  static int adxrs290_probe(struct spi_device *spi)
>  {
>  	struct iio_dev *indio_dev;
> @@ -384,6 +604,7 @@ static int adxrs290_probe(struct spi_device *spi)
>  	indio_dev->channels = adxrs290_channels;
>  	indio_dev->num_channels = ARRAY_SIZE(adxrs290_channels);
>  	indio_dev->info = &adxrs290_info;
> +	indio_dev->available_scan_masks = adxrs290_avail_scan_masks;
>  
>  	mutex_init(&st->lock);
>  
> @@ -416,6 +637,11 @@ static int adxrs290_probe(struct spi_device *spi)
>  	/* max transition time to measurement mode */
>  	msleep(ADXRS290_MAX_TRANSITION_TIME_MS);
>  
> +	ret = devm_add_action_or_reset(&spi->dev, adxrs290_chip_off_action,
> +				       indio_dev);
> +	if (ret < 0)
> +		return ret;
> +
As per comment on v1 (sent just now :) I would move this into the init function.

I don't think it has anything to do with the rest of this patch, so pull it
out as a precursor change before the rest of the set.

>  	ret = adxrs290_get_3db_freq(indio_dev, &val, &val2);
>  	if (ret < 0)
>  		return ret;
> @@ -423,6 +649,17 @@ static int adxrs290_probe(struct spi_device *spi)
>  	st->lpf_3db_freq_idx = val;
>  	st->hpf_3db_freq_idx = val2;
>  
> +	ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
> +					      &iio_pollfunc_store_time,
> +					      &adxrs290_trigger_handler, NULL);
> +	if (ret < 0)
> +		return dev_err_probe(&spi->dev, ret,
> +				     "iio triggered buffer setup failed\n");
> +
> +	ret = adxrs290_probe_trigger(indio_dev);
> +	if (ret < 0)
> +		return ret;
> +
>  	return devm_iio_device_register(&spi->dev, indio_dev);
>  }
>  

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