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From:   "Sa, Nuno" <Nuno.Sa@analog.com>
To:     Ivan Mikhaylov <i.mikhaylov@yadro.com>,
        Jonathan Cameron <jic23@kernel.org>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Peter Meerwald-Stadler <pmeerw@pmeerw.net>
CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>,
        kernel test robot <lkp@intel.com>
Subject: RE: [PATCH v3 1/1] iio: proximity: vcnl3020: add periodic mode
Thread-Topic: [PATCH v3 1/1] iio: proximity: vcnl3020: add periodic mode
Thread-Index: AQHXc/U/Q114uXpUm0OlNRJ4Z2t99Ks6OFFA
Date:   Fri, 9 Jul 2021 07:15:55 +0000
Message-ID: <PH0PR03MB6366A1F0B5AB2963081A8CDB99189@PH0PR03MB6366.namprd03.prod.outlook.com>
References: <20210708124115.558186-1-i.mikhaylov@yadro.com>
 <20210708124115.558186-2-i.mikhaylov@yadro.com>
In-Reply-To: <20210708124115.558186-2-i.mikhaylov@yadro.com>
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Hi Ivan,

This looks good. Some comments inline...

> From: Ivan Mikhaylov <i.mikhaylov@yadro.com>
> Sent: Thursday, July 8, 2021 2:41 PM
> To: Jonathan Cameron <jic23@kernel.org>; Lars-Peter Clausen
> <lars@metafoo.de>; Peter Meerwald-Stadler
> <pmeerw@pmeerw.net>
> Cc: Ivan Mikhaylov <i.mikhaylov@yadro.com>; linux-
> kernel@vger.kernel.org; linux-iio@vger.kernel.org; kernel test robot
> <lkp@intel.com>
> Subject: [PATCH v3 1/1] iio: proximity: vcnl3020: add periodic mode
>=20
> [External]
>=20
> Add the possibility to run proximity sensor in periodic measurement
> mode with thresholds.
>=20
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Ivan Mikhaylov <i.mikhaylov@yadro.com>
> ---
>  drivers/iio/proximity/vcnl3020.c | 297
> ++++++++++++++++++++++++++++++-
>  1 file changed, 295 insertions(+), 2 deletions(-)
>=20
> diff --git a/drivers/iio/proximity/vcnl3020.c
> b/drivers/iio/proximity/vcnl3020.c
> index 43817f6b3086..cd5e9a34b93c 100644
> --- a/drivers/iio/proximity/vcnl3020.c
> +++ b/drivers/iio/proximity/vcnl3020.c
> @@ -3,7 +3,6 @@
>   * Support for Vishay VCNL3020 proximity sensor on i2c bus.
>   * Based on Vishay VCNL4000 driver code.
>   *
> - * TODO: interrupts.
>   */
>=20
>  #include <linux/module.h>
> @@ -11,9 +10,10 @@
>  #include <linux/err.h>
>  #include <linux/delay.h>
>  #include <linux/regmap.h>
> +#include <linux/interrupt.h>
>=20
>  #include <linux/iio/iio.h>
> -#include <linux/iio/sysfs.h>
> +#include <linux/iio/events.h>
>=20
>  #define VCNL3020_PROD_ID	0x21
>=20
> @@ -37,6 +37,21 @@
>  					* measurement
>  					*/
>=20
> +/* Enables periodic proximity measurement */
> +#define VCNL_PS_EN		BIT(1)
> +
> +/* Enables state machine and LP oscillator for self timed
> measurements */
> +#define VCNL_PS_SELFTIMED_EN	BIT(0)
> +
> +/* Bit masks for ICR */
> +
> +/* Enable interrupts on low or high thresholds */
> +#define  VCNL_ICR_THRES_EN	BIT(1)
> +
> +/* Bit masks for ISR */
> +#define VCNL_INT_TH_HI		BIT(0)	/* High threshold hit */
> +#define VCNL_INT_TH_LOW		BIT(1)	/* Low threshold hit */
> +
>  #define VCNL_ON_DEMAND_TIMEOUT_US	100000
>  #define VCNL_POLL_US			20000
>=20
> @@ -215,12 +230,230 @@ static int
> vcnl3020_write_proxy_samp_freq(struct vcnl3020_data *data, int val,
>  	return regmap_write(data->regmap, VCNL_PROXIMITY_RATE,
> index);
>  }
>=20
> +static bool vcnl3020_is_in_periodic_mode(struct vcnl3020_data
> *data)
> +{
> +	int rc;
> +	unsigned int cmd;
> +
> +	rc =3D regmap_read(data->regmap, VCNL_COMMAND, &cmd);
> +	if (rc)
> +		return false;
> +
> +	return !!(cmd & VCNL_PS_SELFTIMED_EN);
> +}
> +
> +static bool vcnl3020_is_thr_enabled(struct vcnl3020_data *data)
> +{
> +	int rc;
> +	unsigned int icr;
> +
> +	rc =3D regmap_read(data->regmap, VCNL_PS_ICR, &icr);
> +	if (rc)
> +		return false;
> +
> +	return !!(icr & VCNL_ICR_THRES_EN);
> +}
> +
> +static int vcnl3020_read_event(struct iio_dev *indio_dev,
> +			       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)
> +{
> +	int rc;
> +	struct vcnl3020_data *data =3D iio_priv(indio_dev);
> +	__be16 res;
> +
> +	switch (info) {
> +	case IIO_EV_INFO_VALUE:
> +		switch (dir) {
> +		case IIO_EV_DIR_RISING:
> +			rc =3D regmap_bulk_read(data->regmap,
> VCNL_PS_HI_THR_HI,
> +					      &res, sizeof(res));

Me and Jonathan actually spoke about this in the beginning of
the week [1]. For IIO we enforce that this has to be DMA safe
even though it's a 2 byte transfer... Check on IIO driver's using
' ____cacheline_aligned'. Note, that it actually matters for the
buffer/data to be the last member of the structure...

> +			if (rc < 0)
> +				return rc;
> +			*val =3D be16_to_cpu(res);
> +			return IIO_VAL_INT;
> +		case IIO_EV_DIR_FALLING:
> +			rc =3D regmap_bulk_read(data->regmap,
> VCNL_PS_LO_THR_HI,
> +					      &res, sizeof(res));
> +			if (rc < 0)
> +				return rc;
> +			*val =3D be16_to_cpu(res);
> +			return IIO_VAL_INT;
> +		default:
> +			return -EINVAL;
> +		}
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int vcnl3020_write_event(struct iio_dev *indio_dev,
> +				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)
> +{
> +	int rc;
> +	__be16 buf;
> +	struct vcnl3020_data *data =3D iio_priv(indio_dev);
> +
> +	mutex_lock(&data->lock);
> +
> +	switch (info) {
> +	case IIO_EV_INFO_VALUE:
> +		switch (dir) {
> +		case IIO_EV_DIR_RISING:
> +			/* 16 bit word/ low * high */
> +			buf =3D cpu_to_be16(val);
> +			rc =3D regmap_bulk_write(data->regmap,
> VCNL_PS_HI_THR_HI,
> +					       &buf, sizeof(buf));

Typically, AFAIK, ' regmap_bulk_write()' creates a DMA safe bounce
buffer for you. However I don't thinks that's done with that in mind
and I don't see anywhere on docs that this is something we can rely
on. Thus, I would also use the DMA safe buffer here and not rely on
regmap implementation details...

> +			if (rc < 0)
> +				goto out_mutex;
> +			rc =3D IIO_VAL_INT;
> +			goto out_mutex;
> +		case IIO_EV_DIR_FALLING:
> +			buf =3D cpu_to_be16(val);
> +			rc =3D regmap_bulk_write(data->regmap,
> VCNL_PS_LO_THR_HI,
> +					       &buf, sizeof(buf));
> +			if (rc < 0)
> +				goto out_mutex;
> +			rc =3D IIO_VAL_INT;
> +			goto out_mutex;
> +		default:
> +			rc =3D -EINVAL;
> +			goto out_mutex;
> +		}
> +	default:
> +		rc =3D -EINVAL;
> +		goto out_mutex;
> +	}
> +out_mutex:
> +	mutex_unlock(&data->lock);
> +
> +	return rc;
> +}
> +
> +static int vcnl3020_enable_periodic(struct iio_dev *indio_dev,
> +				    struct vcnl3020_data *data)
> +{
> +	int rc;
> +	int cmd;
> +
> +	mutex_lock(&data->lock);
> +
> +	/* Enable periodic measurement of proximity data. */
> +	cmd =3D VCNL_PS_EN | VCNL_PS_SELFTIMED_EN;
> +
> +	rc =3D regmap_write(data->regmap, VCNL_COMMAND, cmd);
> +	if (rc)
> +		goto out_mutex;
> +
> +	/*
> +	 * Enable interrupts on threshold, for proximity data by
> +	 * default.
> +	 */
> +	rc =3D regmap_write(data->regmap, VCNL_PS_ICR,
> VCNL_ICR_THRES_EN);
> +
> +out_mutex:
> +	mutex_unlock(&data->lock);
> +
> +	return rc;
> +}
> +
> +static int vcnl3020_disable_periodic(struct iio_dev *indio_dev,
> +				     struct vcnl3020_data *data)
> +{
> +	int rc;
> +
> +	mutex_lock(&data->lock);
> +
> +	rc =3D regmap_write(data->regmap, VCNL_COMMAND, 0);
> +	if (rc)
> +		goto out_mutex;
> +
> +	rc =3D regmap_write(data->regmap, VCNL_PS_ICR, 0);
> +	if (rc)
> +		goto out_mutex;
> +
> +	/* Clear interrupt flag bit */
> +	rc =3D regmap_write(data->regmap, VCNL_ISR, 0);
> +
> +out_mutex:
> +	mutex_unlock(&data->lock);
> +
> +	return rc;
> +}
> +
> +static int vcnl3020_config_threshold(struct iio_dev *indio_dev, bool
> state)
> +{
> +	struct vcnl3020_data *data =3D iio_priv(indio_dev);
> +
> +	if (state) {
> +		return vcnl3020_enable_periodic(indio_dev, data);
> +	} else {
> +		if (!vcnl3020_is_thr_enabled(data))
> +			return 0;
> +		return vcnl3020_disable_periodic(indio_dev, data);
> +	}
> +}
> +
> +static int vcnl3020_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)
> +{
> +	switch (chan->type) {
> +	case IIO_PROXIMITY:
> +		return vcnl3020_config_threshold(indio_dev, state);
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int vcnl3020_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 vcnl3020_data *data =3D iio_priv(indio_dev);
> +
> +	switch (chan->type) {
> +	case IIO_PROXIMITY:
> +		return vcnl3020_is_thr_enabled(data);
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct iio_event_spec vcnl3020_event_spec[] =3D {
> +	{
> +		.type =3D IIO_EV_TYPE_THRESH,
> +		.dir =3D IIO_EV_DIR_RISING,
> +		.mask_separate =3D BIT(IIO_EV_INFO_VALUE),
> +	}, {
> +		.type =3D IIO_EV_TYPE_THRESH,
> +		.dir =3D IIO_EV_DIR_FALLING,
> +		.mask_separate =3D BIT(IIO_EV_INFO_VALUE),
> +	}, {
> +		.type =3D IIO_EV_TYPE_THRESH,
> +		.dir =3D IIO_EV_DIR_EITHER,
> +		.mask_separate =3D BIT(IIO_EV_INFO_ENABLE),
> +	},
> +};
> +
>  static const struct iio_chan_spec vcnl3020_channels[] =3D {
>  	{
>  		.type =3D IIO_PROXIMITY,
>  		.info_mask_separate =3D BIT(IIO_CHAN_INFO_RAW) |
>  				      BIT(IIO_CHAN_INFO_SAMP_FREQ),
>  		.info_mask_separate_available =3D
> BIT(IIO_CHAN_INFO_SAMP_FREQ),
> +		.event_spec =3D vcnl3020_event_spec,
> +		.num_event_specs =3D
> ARRAY_SIZE(vcnl3020_event_spec),
>  	},
>  };
>=20
> @@ -233,6 +466,11 @@ static int vcnl3020_read_raw(struct iio_dev
> *indio_dev,
>=20
>  	switch (mask) {
>  	case IIO_CHAN_INFO_RAW:
> +
> +		/* Protect against event capture. */
> +		if (vcnl3020_is_in_periodic_mode(data))
> +			return -EBUSY;

This does not give you any guarantee that you won't end up calling
'vcnl3020_measure_proximity()' with periodic mode enabled... The
'if()' should be done under the same data lock that you use for
enabling/disabling this mode. Just push the check inside
'vcnl3020_measure_proximity()'.

>  		rc =3D vcnl3020_measure_proximity(data, val);
>  		if (rc)
>  			return rc;
> @@ -254,6 +492,10 @@ static int vcnl3020_write_raw(struct iio_dev
> *indio_dev,
>  	int rc;
>  	struct vcnl3020_data *data =3D iio_priv(indio_dev);
>=20
> +	/* Protect against event capture. */
> +	if (vcnl3020_is_in_periodic_mode(data))
> +		return -EBUSY;

ditto...

[1]: https://marc.info/?l=3Dlinux-kernel&m=3D162556231125061&w=3D2
- Nuno S=E1

>  	switch (mask) {
>  	case IIO_CHAN_INFO_SAMP_FREQ:
>  		rc =3D iio_device_claim_direct_mode(indio_dev);
> @@ -287,6 +529,10 @@ static const struct iio_info vcnl3020_info =3D {
>  	.read_raw =3D vcnl3020_read_raw,
>  	.write_raw =3D vcnl3020_write_raw,
>  	.read_avail =3D vcnl3020_read_avail,
> +	.read_event_value =3D vcnl3020_read_event,
> +	.write_event_value =3D vcnl3020_write_event,
> +	.read_event_config =3D vcnl3020_read_event_config,
> +	.write_event_config =3D vcnl3020_write_event_config,
>  };
>=20
>  static const struct regmap_config vcnl3020_regmap_config =3D {
> @@ -295,6 +541,40 @@ static const struct regmap_config
> vcnl3020_regmap_config =3D {
>  	.max_register	=3D VCNL_PS_MOD_ADJ,
>  };
>=20
> +static irqreturn_t vcnl3020_handle_irq_thread(int irq, void *p)
> +{
> +	struct iio_dev *indio_dev =3D p;
> +	struct vcnl3020_data *data =3D iio_priv(indio_dev);
> +	unsigned int isr;
> +	int rc;
> +
> +	rc =3D regmap_read(data->regmap, VCNL_ISR, &isr);
> +	if (rc) {
> +		dev_err(data->dev, "Error (%d) reading reg (0x%x)\n",
> +			rc, VCNL_ISR);
> +		return IRQ_HANDLED;
> +	}
> +
> +	if (isr & VCNL_ICR_THRES_EN) {
> +		iio_push_event(indio_dev,
> +
> IIO_UNMOD_EVENT_CODE(IIO_PROXIMITY,
> +						    1,
> +						    IIO_EV_TYPE_THRESH,
> +						    IIO_EV_DIR_RISING),
> +			       iio_get_time_ns(indio_dev));
> +
> +		rc =3D regmap_write(data->regmap, VCNL_ISR,
> +				  isr & VCNL_ICR_THRES_EN);
> +		if (rc)
> +			dev_err(data->dev, "Error (%d) writing in reg
> (0x%x)\n",
> +				rc, VCNL_ISR);
> +	} else {
> +		return IRQ_NONE;
> +	}
> +
> +	return IRQ_HANDLED;
> +}
> +
>  static int vcnl3020_probe(struct i2c_client *client)
>  {
>  	struct vcnl3020_data *data;
> @@ -327,6 +607,19 @@ static int vcnl3020_probe(struct i2c_client
> *client)
>  	indio_dev->name =3D "vcnl3020";
>  	indio_dev->modes =3D INDIO_DIRECT_MODE;
>=20
> +	if (client->irq) {
> +		rc =3D devm_request_threaded_irq(&client->dev, client-
> >irq,
> +					       NULL,
> vcnl3020_handle_irq_thread,
> +					       IRQF_ONESHOT, indio_dev-
> >name,
> +					       indio_dev);
> +		if (rc) {
> +			dev_err(&client->dev,
> +				"Error (%d) irq request failed (%u)\n",
> rc,
> +				client->irq);
> +			return rc;
> +		}
> +	}
> +
>  	return devm_iio_device_register(&client->dev, indio_dev);
>  }
>=20
> --
> 2.31.1