[RFC 0/2] iio: Add single and double tap events support

[RFC 0/2] iio: Add single and double tap events support

[Jagath Jog J]

This patch series adds new event type for tap called gesture and direction
is used to differentiate single and double tap. This series adds single
and double tap support for bma400 accelerometer device driver.

Jagath Jog J (2):
  iio: Add new event type gesture and use direction for single and
    double tap
  iio: accel: bma400: Add support for single and double tap events

 Documentation/ABI/testing/sysfs-bus-iio |  19 +++
 drivers/iio/accel/bma400.h              |  11 ++
 drivers/iio/accel/bma400_core.c         | 186 ++++++++++++++++++++++--
 drivers/iio/industrialio-event.c        |   5 +-
 include/uapi/linux/iio/types.h          |   3 +
 tools/iio/iio_event_monitor.c           |   8 +-
 6 files changed, 221 insertions(+), 11 deletions(-)


base-commit: c321674386d8d5597831cbf980f566df8c98d4c1
-- 
2.17.1

[RFC 1/2] iio: Add new event type gesture and use direction for single and double tap

[Jagath Jog J]

Add new event type for tap called gesture and the direction can be used
to differentiate single and double tap. This may be used by accelerometer
sensors to express single and double tap events. For directional tap,
modifiers like IIO_MOD_(X/Y/Z) can be used along with singletap and
doubletap direction.

Signed-off-by: Jagath Jog J <jagathjog1996@gmail.com>
---
 Documentation/ABI/testing/sysfs-bus-iio | 19 +++++++++++++++++++
 drivers/iio/industrialio-event.c        |  5 ++++-
 include/uapi/linux/iio/types.h          |  3 +++
 tools/iio/iio_event_monitor.c           |  8 +++++++-
 4 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index 3e00d7f7ee22..2d4866203ccf 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -2035,3 +2035,22 @@ Description:
 		Available range for the forced calibration value, expressed as:
 
 		- a range specified as "[min step max]"
+
+What:		/sys/.../events/in_accel_gesture_singletap_en
+What:		/sys/.../events/in_accel_gesture_doubletap_en
+KernelVersion:	5.19
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Accelerometer device detects single or double taps and generate
+		events when threshold for minimum tap amplitide passes.
+		E.g. a single tap event is generated when acceleration value
+		crosses the minimum tap amplitude value set. Where tap threshold
+		value is set by using in_accel_gesture_singletap_value.
+
+What:		/sys/.../events/in_accel_gesture_singletap_value
+What:		/sys/.../events/in_accel_gesture_doubletap_value
+KernelVersion:	5.19
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Specifies the threshold value that the device is comparing
+		against to generate the tap gesture event.
diff --git a/drivers/iio/industrialio-event.c b/drivers/iio/industrialio-event.c
index b5e059e15b0a..22d59eb0a8a2 100644
--- a/drivers/iio/industrialio-event.c
+++ b/drivers/iio/industrialio-event.c
@@ -231,12 +231,15 @@ static const char * const iio_ev_type_text[] = {
 	[IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
 	[IIO_EV_TYPE_CHANGE] = "change",
 	[IIO_EV_TYPE_MAG_REFERENCED] = "mag_referenced",
+	[IIO_EV_TYPE_GESTURE] = "gesture",
 };
 
 static const char * const iio_ev_dir_text[] = {
 	[IIO_EV_DIR_EITHER] = "either",
 	[IIO_EV_DIR_RISING] = "rising",
-	[IIO_EV_DIR_FALLING] = "falling"
+	[IIO_EV_DIR_FALLING] = "falling",
+	[IIO_EV_DIR_SINGLETAP] = "singletap",
+	[IIO_EV_DIR_DOUBLETAP] = "doubletap",
 };
 
 static const char * const iio_ev_info_text[] = {
diff --git a/include/uapi/linux/iio/types.h b/include/uapi/linux/iio/types.h
index 472cead10d8d..913864221ac4 100644
--- a/include/uapi/linux/iio/types.h
+++ b/include/uapi/linux/iio/types.h
@@ -105,6 +105,7 @@ enum iio_event_type {
 	IIO_EV_TYPE_MAG_ADAPTIVE,
 	IIO_EV_TYPE_CHANGE,
 	IIO_EV_TYPE_MAG_REFERENCED,
+	IIO_EV_TYPE_GESTURE,
 };
 
 enum iio_event_direction {
@@ -112,6 +113,8 @@ enum iio_event_direction {
 	IIO_EV_DIR_RISING,
 	IIO_EV_DIR_FALLING,
 	IIO_EV_DIR_NONE,
+	IIO_EV_DIR_SINGLETAP,
+	IIO_EV_DIR_DOUBLETAP,
 };
 
 #endif /* _UAPI_IIO_TYPES_H_ */
diff --git a/tools/iio/iio_event_monitor.c b/tools/iio/iio_event_monitor.c
index 2f4581658859..b3b3ea399f67 100644
--- a/tools/iio/iio_event_monitor.c
+++ b/tools/iio/iio_event_monitor.c
@@ -69,12 +69,15 @@ static const char * const iio_ev_type_text[] = {
 	[IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
 	[IIO_EV_TYPE_CHANGE] = "change",
 	[IIO_EV_TYPE_MAG_REFERENCED] = "mag_referenced",
+	[IIO_EV_TYPE_GESTURE] = "gesture",
 };
 
 static const char * const iio_ev_dir_text[] = {
 	[IIO_EV_DIR_EITHER] = "either",
 	[IIO_EV_DIR_RISING] = "rising",
-	[IIO_EV_DIR_FALLING] = "falling"
+	[IIO_EV_DIR_FALLING] = "falling",
+	[IIO_EV_DIR_SINGLETAP] = "singletap",
+	[IIO_EV_DIR_DOUBLETAP] = "doubletap",
 };
 
 static const char * const iio_modifier_names[] = {
@@ -227,6 +230,7 @@ static bool event_is_known(struct iio_event_data *event)
 	case IIO_EV_TYPE_THRESH_ADAPTIVE:
 	case IIO_EV_TYPE_MAG_ADAPTIVE:
 	case IIO_EV_TYPE_CHANGE:
+	case IIO_EV_TYPE_GESTURE:
 		break;
 	default:
 		return false;
@@ -236,6 +240,8 @@ static bool event_is_known(struct iio_event_data *event)
 	case IIO_EV_DIR_EITHER:
 	case IIO_EV_DIR_RISING:
 	case IIO_EV_DIR_FALLING:
+	case IIO_EV_DIR_SINGLETAP:
+	case IIO_EV_DIR_DOUBLETAP:
 	case IIO_EV_DIR_NONE:
 		break;
 	default:
-- 
2.17.1

[RFC 2/2] iio: accel: bma400: Add support for single and double tap events

[Jagath Jog J]

Add support for single and double tap events based on the tap threshold
value and minimum quite time value between the taps. INT1 pin is used to
interrupt and event is pushed to userspace.

Signed-off-by: Jagath Jog J <jagathjog1996@gmail.com>
---
 drivers/iio/accel/bma400.h      |  11 ++
 drivers/iio/accel/bma400_core.c | 186 ++++++++++++++++++++++++++++++--
 2 files changed, 188 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/accel/bma400.h b/drivers/iio/accel/bma400.h
index e8f802a82300..7331474433fa 100644
--- a/drivers/iio/accel/bma400.h
+++ b/drivers/iio/accel/bma400.h
@@ -40,6 +40,7 @@
 #define BMA400_INT_STAT1_REG        0x0f
 #define BMA400_INT_STAT2_REG        0x10
 #define BMA400_INT12_MAP_REG        0x23
+#define BMA400_INT_ENG_OVRUN_MSK    BIT(4)
 
 /* Temperature register */
 #define BMA400_TEMP_DATA_REG        0x11
@@ -105,6 +106,16 @@
 #define BMA400_INT_GEN2_MSK         BIT(3)
 #define BMA400_GEN_HYST_MSK         GENMASK(1, 0)
 
+/* TAP config registers */
+#define BMA400_TAP_CONFIG           0x57
+#define BMA400_TAP_CONFIG1          0x58
+#define BMA400_S_TAP_MSK            BIT(2)
+#define BMA400_D_TAP_MSK            BIT(3)
+#define BMA400_INT_S_TAP_MSK        BIT(10)
+#define BMA400_INT_D_TAP_MSK        BIT(11)
+#define BMA400_TAP_SEN_MSK          GENMASK(2, 0)
+#define BMA400_TAP_QUITE_MSK        GENMASK(3, 2)
+
 /*
  * BMA400_SCALE_MIN macro value represents m/s^2 for 1 LSB before
  * converting to micro values for +-2g range.
diff --git a/drivers/iio/accel/bma400_core.c b/drivers/iio/accel/bma400_core.c
index 517920400df1..2385883707f2 100644
--- a/drivers/iio/accel/bma400_core.c
+++ b/drivers/iio/accel/bma400_core.c
@@ -88,6 +88,7 @@ struct bma400_data {
 	bool step_event_en;
 	bool activity_event_en;
 	unsigned int generic_event_en;
+	unsigned int tap_event_en;
 	/* Correct time stamp alignment */
 	struct {
 		__le16 buff[3];
@@ -216,6 +217,19 @@ static const struct iio_event_spec bma400_accel_event[] = {
 				       BIT(IIO_EV_INFO_HYSTERESIS) |
 				       BIT(IIO_EV_INFO_ENABLE),
 	},
+	{
+		.type = IIO_EV_TYPE_GESTURE,
+		.dir = IIO_EV_DIR_SINGLETAP,
+		.mask_shared_by_type = BIT(IIO_EV_INFO_VALUE) |
+				       BIT(IIO_EV_INFO_ENABLE),
+	},
+	{
+		.type = IIO_EV_TYPE_GESTURE,
+		.dir = IIO_EV_DIR_DOUBLETAP,
+		.mask_shared_by_type = BIT(IIO_EV_INFO_VALUE) |
+				       BIT(IIO_EV_INFO_PERIOD) |
+				       BIT(IIO_EV_INFO_ENABLE),
+	},
 };
 
 #define BMA400_ACC_CHANNEL(_index, _axis) { \
@@ -407,6 +421,14 @@ static int bma400_set_accel_output_data_rate(struct bma400_data *data,
 	unsigned int val;
 	int ret;
 
+	/*
+	 * No need to change ODR when tap event is enabled because
+	 * tap interrupt is operating with the data rate of 200Hz.
+	 * See datasheet page 124.
+	 */
+	if (data->tap_event_en)
+		return -EBUSY;
+
 	if (hz >= BMA400_ACC_ODR_MIN_WHOLE_HZ) {
 		if (uhz || hz > BMA400_ACC_ODR_MAX_HZ)
 			return -EINVAL;
@@ -1012,6 +1034,10 @@ static int bma400_read_event_config(struct iio_dev *indio_dev,
 		case IIO_EV_DIR_FALLING:
 			return FIELD_GET(BMA400_INT_GEN2_MSK,
 					 data->generic_event_en);
+		case IIO_EV_DIR_SINGLETAP:
+			return FIELD_GET(BMA400_S_TAP_MSK, data->tap_event_en);
+		case IIO_EV_DIR_DOUBLETAP:
+			return FIELD_GET(BMA400_D_TAP_MSK, data->tap_event_en);
 		default:
 			return -EINVAL;
 		}
@@ -1101,6 +1127,74 @@ static int bma400_activity_event_en(struct bma400_data *data,
 	return 0;
 }
 
+static int bma400_tap_event_enable(struct bma400_data *data,
+				   enum iio_event_direction dir, int state)
+{
+	int ret;
+	unsigned int mask, field_value;
+
+	if (data->power_mode == POWER_MODE_SLEEP)
+		return -EBUSY;
+
+	/*
+	 * acc_filt1 is the data source for the tap interrupt and it is
+	 * operating on an input data rate of 200Hz.
+	 */
+	if (!data->tap_event_en) {
+		ret = bma400_set_accel_output_data_rate(data, 200, 0);
+		if (ret)
+			return ret;
+	}
+
+	ret = regmap_update_bits(data->regmap, BMA400_INT12_MAP_REG,
+				 BMA400_S_TAP_MSK,
+				 FIELD_PREP(BMA400_S_TAP_MSK, state));
+	if (ret)
+		return ret;
+
+	switch (dir) {
+	case IIO_EV_DIR_SINGLETAP:
+		mask = BMA400_S_TAP_MSK;
+		set_mask_bits(&field_value, BMA400_S_TAP_MSK,
+			      FIELD_PREP(BMA400_S_TAP_MSK, state));
+		break;
+	case IIO_EV_DIR_DOUBLETAP:
+		mask = BMA400_D_TAP_MSK;
+		set_mask_bits(&field_value, BMA400_D_TAP_MSK,
+			      FIELD_PREP(BMA400_D_TAP_MSK, state));
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = regmap_update_bits(data->regmap, BMA400_INT_CONFIG1_REG, mask,
+				 field_value);
+	if (ret)
+		return ret;
+
+	set_mask_bits(&data->tap_event_en, mask, field_value);
+	return 0;
+}
+
+static int bma400_disable_adv_interrupt(struct bma400_data *data)
+{
+	int ret;
+
+	ret = regmap_write(data->regmap, BMA400_INT_CONFIG0_REG, 0);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(data->regmap, BMA400_INT_CONFIG1_REG, 0);
+	if (ret)
+		return ret;
+
+	data->tap_event_en = 0;
+	data->generic_event_en = 0;
+	data->step_event_en = 0;
+	data->activity_event_en = 0;
+	return 0;
+}
+
 static int bma400_write_event_config(struct iio_dev *indio_dev,
 				     const struct iio_chan_spec *chan,
 				     enum iio_event_type type,
@@ -1111,10 +1205,20 @@ static int bma400_write_event_config(struct iio_dev *indio_dev,
 
 	switch (chan->type) {
 	case IIO_ACCEL:
-		mutex_lock(&data->mutex);
-		ret = bma400_activity_event_en(data, dir, state);
-		mutex_unlock(&data->mutex);
-		return ret;
+		switch (type) {
+		case IIO_EV_TYPE_MAG:
+			mutex_lock(&data->mutex);
+			ret = bma400_activity_event_en(data, dir, state);
+			mutex_unlock(&data->mutex);
+			return ret;
+		case IIO_EV_TYPE_GESTURE:
+			mutex_lock(&data->mutex);
+			ret = bma400_tap_event_enable(data, dir, state);
+			mutex_unlock(&data->mutex);
+			return ret;
+		default:
+			return -EINVAL;
+		}
 	case IIO_STEPS:
 		mutex_lock(&data->mutex);
 		ret = bma400_steps_event_enable(data, state);
@@ -1159,8 +1263,8 @@ static int bma400_read_event_value(struct iio_dev *indio_dev,
 	struct bma400_data *data = iio_priv(indio_dev);
 	int ret, reg;
 
-	switch (chan->type) {
-	case IIO_ACCEL:
+	switch (type) {
+	case IIO_EV_TYPE_MAG:
 		reg = get_gen_config_reg(dir);
 		if (reg < 0)
 			return -EINVAL;
@@ -1196,6 +1300,25 @@ static int bma400_read_event_value(struct iio_dev *indio_dev,
 		default:
 			return -EINVAL;
 		}
+	case IIO_EV_TYPE_GESTURE:
+		switch (info) {
+		case IIO_EV_INFO_VALUE:
+			ret = regmap_read(data->regmap,
+					  BMA400_TAP_CONFIG, val);
+			if (ret)
+				return ret;
+			*val = FIELD_GET(BMA400_TAP_SEN_MSK, *val);
+			return IIO_VAL_INT;
+		case IIO_EV_INFO_PERIOD:
+			ret = regmap_read(data->regmap,
+					  BMA400_TAP_CONFIG1, val);
+			if (ret)
+				return ret;
+			*val = FIELD_GET(BMA400_TAP_QUITE_MSK, *val);
+			return IIO_VAL_INT;
+		default:
+			return -EINVAL;
+		}
 	default:
 		return -EINVAL;
 	}
@@ -1211,8 +1334,8 @@ static int bma400_write_event_value(struct iio_dev *indio_dev,
 	struct bma400_data *data = iio_priv(indio_dev);
 	int reg, ret;
 
-	switch (chan->type) {
-	case IIO_ACCEL:
+	switch (type) {
+	case IIO_EV_TYPE_MAG:
 		reg = get_gen_config_reg(dir);
 		if (reg < 0)
 			return -EINVAL;
@@ -1228,7 +1351,6 @@ static int bma400_write_event_value(struct iio_dev *indio_dev,
 		case IIO_EV_INFO_PERIOD:
 			if (val < 1 || val > 65535)
 				return -EINVAL;
-
 			mutex_lock(&data->mutex);
 			put_unaligned_be16(val, &data->duration);
 			ret = regmap_bulk_write(data->regmap,
@@ -1248,6 +1370,30 @@ static int bma400_write_event_value(struct iio_dev *indio_dev,
 		default:
 			return -EINVAL;
 		}
+	case IIO_EV_TYPE_GESTURE:
+		switch (info) {
+		case IIO_EV_INFO_VALUE:
+			if (val < 0 || val > 7)
+				return -EINVAL;
+
+			return regmap_update_bits(data->regmap,
+						  BMA400_TAP_CONFIG,
+						  BMA400_TAP_SEN_MSK,
+						  FIELD_PREP(BMA400_TAP_SEN_MSK,
+							     val));
+
+		case IIO_EV_INFO_PERIOD:
+			if (val < 0 || val > 3)
+				return -EINVAL;
+
+			return regmap_update_bits(data->regmap,
+						  BMA400_TAP_CONFIG1,
+						  BMA400_TAP_QUITE_MSK,
+						  FIELD_PREP(BMA400_TAP_QUITE_MSK,
+							     val));
+		default:
+			return -EINVAL;
+		}
 	default:
 		return -EINVAL;
 	}
@@ -1350,6 +1496,28 @@ static irqreturn_t bma400_interrupt(int irq, void *private)
 	if (ret || !data->status)
 		goto unlock_err;
 
+	/* Disable all advance interrupts if interrupt engine overrun occurs */
+	if (FIELD_GET(BMA400_INT_ENG_OVRUN_MSK, le16_to_cpu(data->status))) {
+		bma400_disable_adv_interrupt(data);
+		dev_err(data->dev, "Interrupt engine overrun\n");
+		goto unlock_err;
+	}
+
+	if (FIELD_GET(BMA400_INT_S_TAP_MSK, le16_to_cpu(data->status)))
+		ev_dir = IIO_EV_DIR_SINGLETAP;
+
+	if (FIELD_GET(BMA400_INT_D_TAP_MSK, le16_to_cpu(data->status)))
+		ev_dir = IIO_EV_DIR_DOUBLETAP;
+
+	if (ev_dir != IIO_EV_DIR_NONE) {
+		iio_push_event(indio_dev,
+			       IIO_MOD_EVENT_CODE(IIO_ACCEL, 0,
+						  IIO_MOD_X_OR_Y_OR_Z,
+						  IIO_EV_TYPE_GESTURE, ev_dir),
+			       timestamp);
+	}
+
+	ev_dir = IIO_EV_DIR_NONE;
 	if (FIELD_GET(BMA400_INT_GEN1_MSK, le16_to_cpu(data->status)))
 		ev_dir = IIO_EV_DIR_RISING;
 
-- 
2.17.1

Re: [RFC 2/2] iio: accel: bma400: Add support for single and double tap events

[Andy Shevchenko]

On Sun, May 29, 2022 at 6:02 AM Jagath Jog J <jagathjog1996@gmail.com> wrote:
>
> Add support for single and double tap events based on the tap threshold
> value and minimum quite time value between the taps. INT1 pin is used to

quiet (see below as well)

The INT1

> interrupt and event is pushed to userspace.

an event

...

> +#define BMA400_TAP_QUITE_MSK        GENMASK(3, 2)

QUIET ?

...

> +       /*
> +        * No need to change ODR when tap event is enabled because
> +        * tap interrupt is operating with the data rate of 200Hz.
> +        * See datasheet page 124.

When referring to the datasheet, please be more specific, i.e. table /
chart / section number and name, No page needed as it may  be changed
from version to version, also date of the document or revision would
be nice to add.

> +        */

-- 
With Best Regards,
Andy Shevchenko

Re: [RFC 1/2] iio: Add new event type gesture and use direction for single and double tap

[Jonathan Cameron]

On Sun, 29 May 2022 09:31:52 +0530
Jagath Jog J <jagathjog1996@gmail.com> wrote:

> Add new event type for tap called gesture and the direction can be used
> to differentiate single and double tap. This may be used by accelerometer
> sensors to express single and double tap events. For directional tap,
> modifiers like IIO_MOD_(X/Y/Z) can be used along with singletap and
> doubletap direction.
> 
> Signed-off-by: Jagath Jog J <jagathjog1996@gmail.com>

Looks good to me in general. A few comments on the documentation. 

I briefly thought about whether we should make the direction enum dependent
on the type of channel, but then I checked and we have 7 bits for that
fields, so 'hopefully' we will always have plenty of space.

If people start defining 100s of gestures we may need to rethink.

This is bold new userspace ABI, so I definitely want to give this
more time on the list for others to have the opportunity to take a look
and think about whether it works for their devices etc.

Thanks,

Jonathan

> ---
>  Documentation/ABI/testing/sysfs-bus-iio | 19 +++++++++++++++++++
>  drivers/iio/industrialio-event.c        |  5 ++++-
>  include/uapi/linux/iio/types.h          |  3 +++
>  tools/iio/iio_event_monitor.c           |  8 +++++++-
>  4 files changed, 33 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
> index 3e00d7f7ee22..2d4866203ccf 100644
> --- a/Documentation/ABI/testing/sysfs-bus-iio
> +++ b/Documentation/ABI/testing/sysfs-bus-iio
> @@ -2035,3 +2035,22 @@ Description:
>  		Available range for the forced calibration value, expressed as:
>  
>  		- a range specified as "[min step max]"
> +
> +What:		/sys/.../events/in_accel_gesture_singletap_en
> +What:		/sys/.../events/in_accel_gesture_doubletap_en
> +KernelVersion:	5.19
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Accelerometer device detects single or double taps and generate
> +		events when threshold for minimum tap amplitide passes.

I'd keep this a little more vague as different accelerometers have different
magic algorithms to detect this and we don't want to care about how they do
it.

> +		E.g. a single tap event is generated when acceleration value
> +		crosses the minimum tap amplitude value set. Where tap threshold
> +		value is set by using in_accel_gesture_singletap_value.

That's a very simplistic tap detector. Given the control on the threshold
on the bma400 is a whole 3 bits, I'd not what to hazard any guess to
what 'tap sensitivity is'.

So I'd make this description much less specific. (even drop the device type)
Perhaps:

"Device generates an event on a single or double tap".

> +
> +What:		/sys/.../events/in_accel_gesture_singletap_value
> +What:		/sys/.../events/in_accel_gesture_doubletap_value
> +KernelVersion:	5.19
> +Contact:	linux-iio@vger.kernel.org
> +Description:
> +		Specifies the threshold value that the device is comparing
> +		against to generate the tap gesture event.

This is why 'gesture' detection is a pain.   What are the units of this
value?  (typically tap detection is done via some mixture of jerk and
thresholds on the raw acceleration plus temporal constraints).  

Perhaps for now, we just add a sentence that says.

'Units and exact meaning are device specific.' ?



> diff --git a/drivers/iio/industrialio-event.c b/drivers/iio/industrialio-event.c
> index b5e059e15b0a..22d59eb0a8a2 100644
> --- a/drivers/iio/industrialio-event.c
> +++ b/drivers/iio/industrialio-event.c
> @@ -231,12 +231,15 @@ static const char * const iio_ev_type_text[] = {
>  	[IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
>  	[IIO_EV_TYPE_CHANGE] = "change",
>  	[IIO_EV_TYPE_MAG_REFERENCED] = "mag_referenced",
> +	[IIO_EV_TYPE_GESTURE] = "gesture",
>  };
>  
>  static const char * const iio_ev_dir_text[] = {
>  	[IIO_EV_DIR_EITHER] = "either",
>  	[IIO_EV_DIR_RISING] = "rising",
> -	[IIO_EV_DIR_FALLING] = "falling"
> +	[IIO_EV_DIR_FALLING] = "falling",
> +	[IIO_EV_DIR_SINGLETAP] = "singletap",
> +	[IIO_EV_DIR_DOUBLETAP] = "doubletap",
>  };
>  
>  static const char * const iio_ev_info_text[] = {
> diff --git a/include/uapi/linux/iio/types.h b/include/uapi/linux/iio/types.h
> index 472cead10d8d..913864221ac4 100644
> --- a/include/uapi/linux/iio/types.h
> +++ b/include/uapi/linux/iio/types.h
> @@ -105,6 +105,7 @@ enum iio_event_type {
>  	IIO_EV_TYPE_MAG_ADAPTIVE,
>  	IIO_EV_TYPE_CHANGE,
>  	IIO_EV_TYPE_MAG_REFERENCED,
> +	IIO_EV_TYPE_GESTURE,
>  };
>  
>  enum iio_event_direction {
> @@ -112,6 +113,8 @@ enum iio_event_direction {
>  	IIO_EV_DIR_RISING,
>  	IIO_EV_DIR_FALLING,
>  	IIO_EV_DIR_NONE,
> +	IIO_EV_DIR_SINGLETAP,
> +	IIO_EV_DIR_DOUBLETAP,
>  };
>  
>  #endif /* _UAPI_IIO_TYPES_H_ */
> diff --git a/tools/iio/iio_event_monitor.c b/tools/iio/iio_event_monitor.c
> index 2f4581658859..b3b3ea399f67 100644
> --- a/tools/iio/iio_event_monitor.c
> +++ b/tools/iio/iio_event_monitor.c
> @@ -69,12 +69,15 @@ static const char * const iio_ev_type_text[] = {
>  	[IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
>  	[IIO_EV_TYPE_CHANGE] = "change",
>  	[IIO_EV_TYPE_MAG_REFERENCED] = "mag_referenced",
> +	[IIO_EV_TYPE_GESTURE] = "gesture",
>  };
>  
>  static const char * const iio_ev_dir_text[] = {
>  	[IIO_EV_DIR_EITHER] = "either",
>  	[IIO_EV_DIR_RISING] = "rising",
> -	[IIO_EV_DIR_FALLING] = "falling"
> +	[IIO_EV_DIR_FALLING] = "falling",
> +	[IIO_EV_DIR_SINGLETAP] = "singletap",
> +	[IIO_EV_DIR_DOUBLETAP] = "doubletap",
>  };
>  
>  static const char * const iio_modifier_names[] = {
> @@ -227,6 +230,7 @@ static bool event_is_known(struct iio_event_data *event)
>  	case IIO_EV_TYPE_THRESH_ADAPTIVE:
>  	case IIO_EV_TYPE_MAG_ADAPTIVE:
>  	case IIO_EV_TYPE_CHANGE:
> +	case IIO_EV_TYPE_GESTURE:
>  		break;
>  	default:
>  		return false;
> @@ -236,6 +240,8 @@ static bool event_is_known(struct iio_event_data *event)
>  	case IIO_EV_DIR_EITHER:
>  	case IIO_EV_DIR_RISING:
>  	case IIO_EV_DIR_FALLING:
> +	case IIO_EV_DIR_SINGLETAP:
> +	case IIO_EV_DIR_DOUBLETAP:
>  	case IIO_EV_DIR_NONE:
>  		break;
>  	default:

Re: [RFC 2/2] iio: accel: bma400: Add support for single and double tap events

[Jonathan Cameron]

On Sun, 29 May 2022 09:31:53 +0530
Jagath Jog J <jagathjog1996@gmail.com> wrote:

> Add support for single and double tap events based on the tap threshold
> value and minimum quite time value between the taps. INT1 pin is used to
> interrupt and event is pushed to userspace.
> 
> Signed-off-by: Jagath Jog J <jagathjog1996@gmail.com>

Hi Jagath,

A few comments inline.

Thanks,

Jonathan

> ---
>  drivers/iio/accel/bma400.h      |  11 ++
>  drivers/iio/accel/bma400_core.c | 186 ++++++++++++++++++++++++++++++--
>  2 files changed, 188 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/iio/accel/bma400.h b/drivers/iio/accel/bma400.h
> index e8f802a82300..7331474433fa 100644
> --- a/drivers/iio/accel/bma400.h
> +++ b/drivers/iio/accel/bma400.h
> @@ -40,6 +40,7 @@
>  #define BMA400_INT_STAT1_REG        0x0f
>  #define BMA400_INT_STAT2_REG        0x10
>  #define BMA400_INT12_MAP_REG        0x23
> +#define BMA400_INT_ENG_OVRUN_MSK    BIT(4)
>  
>  /* Temperature register */
>  #define BMA400_TEMP_DATA_REG        0x11
> @@ -105,6 +106,16 @@
>  #define BMA400_INT_GEN2_MSK         BIT(3)
>  #define BMA400_GEN_HYST_MSK         GENMASK(1, 0)
>  
> +/* TAP config registers */
> +#define BMA400_TAP_CONFIG           0x57
> +#define BMA400_TAP_CONFIG1          0x58
> +#define BMA400_S_TAP_MSK            BIT(2)
> +#define BMA400_D_TAP_MSK            BIT(3)
> +#define BMA400_INT_S_TAP_MSK        BIT(10)
> +#define BMA400_INT_D_TAP_MSK        BIT(11)
> +#define BMA400_TAP_SEN_MSK          GENMASK(2, 0)
> +#define BMA400_TAP_QUITE_MSK        GENMASK(3, 2)
> +
>  /*
>   * BMA400_SCALE_MIN macro value represents m/s^2 for 1 LSB before
>   * converting to micro values for +-2g range.
> diff --git a/drivers/iio/accel/bma400_core.c b/drivers/iio/accel/bma400_core.c
> index 517920400df1..2385883707f2 100644
> --- a/drivers/iio/accel/bma400_core.c
> +++ b/drivers/iio/accel/bma400_core.c
> @@ -88,6 +88,7 @@ struct bma400_data {
>  	bool step_event_en;
>  	bool activity_event_en;
>  	unsigned int generic_event_en;
> +	unsigned int tap_event_en;
>  	/* Correct time stamp alignment */
>  	struct {
>  		__le16 buff[3];
> @@ -216,6 +217,19 @@ static const struct iio_event_spec bma400_accel_event[] = {
>  				       BIT(IIO_EV_INFO_HYSTERESIS) |
>  				       BIT(IIO_EV_INFO_ENABLE),
>  	},
> +	{
> +		.type = IIO_EV_TYPE_GESTURE,
> +		.dir = IIO_EV_DIR_SINGLETAP,
> +		.mask_shared_by_type = BIT(IIO_EV_INFO_VALUE) |
> +				       BIT(IIO_EV_INFO_ENABLE),
> +	},
> +	{
> +		.type = IIO_EV_TYPE_GESTURE,
> +		.dir = IIO_EV_DIR_DOUBLETAP,
> +		.mask_shared_by_type = BIT(IIO_EV_INFO_VALUE) |
> +				       BIT(IIO_EV_INFO_PERIOD) |

Feels like period isn't well defined for this case.  So probably needs a specific
ABI entry and period might not be best choice...  However, period has no logical
other meaning in this case (what does 'amount of time a double tap has been true for before
event mean?') so I think it is fine to use it, as long as ABI docs exist to say what it's
meaning is for this case.

> +				       BIT(IIO_EV_INFO_ENABLE),
> +	},
>  };
>  
>  #define BMA400_ACC_CHANNEL(_index, _axis) { \
> @@ -407,6 +421,14 @@ static int bma400_set_accel_output_data_rate(struct bma400_data *data,
>  	unsigned int val;
>  	int ret;
>  
> +	/*
> +	 * No need to change ODR when tap event is enabled because

Do not change ODR...


> +	 * tap interrupt is operating with the data rate of 200Hz.
> +	 * See datasheet page 124.
> +	 */
> +	if (data->tap_event_en)
> +		return -EBUSY;
> +
>  	if (hz >= BMA400_ACC_ODR_MIN_WHOLE_HZ) {
>  		if (uhz || hz > BMA400_ACC_ODR_MAX_HZ)
>  			return -EINVAL;
> @@ -1012,6 +1034,10 @@ static int bma400_read_event_config(struct iio_dev *indio_dev,
>  		case IIO_EV_DIR_FALLING:
>  			return FIELD_GET(BMA400_INT_GEN2_MSK,
>  					 data->generic_event_en);
> +		case IIO_EV_DIR_SINGLETAP:
> +			return FIELD_GET(BMA400_S_TAP_MSK, data->tap_event_en);
> +		case IIO_EV_DIR_DOUBLETAP:
> +			return FIELD_GET(BMA400_D_TAP_MSK, data->tap_event_en);
>  		default:
>  			return -EINVAL;
>  		}
> @@ -1101,6 +1127,74 @@ static int bma400_activity_event_en(struct bma400_data *data,
>  	return 0;
>  }
>  
> +static int bma400_tap_event_enable(struct bma400_data *data,
> +				   enum iio_event_direction dir, int state)
> +{
> +	int ret;
> +	unsigned int mask, field_value;
> +
> +	if (data->power_mode == POWER_MODE_SLEEP)
> +		return -EBUSY;

There are existing examples of this in driver, but I can't immediately
see how we end up in sleep mode.  Perhaps a comment on why this might happen?

> +
> +	/*
> +	 * acc_filt1 is the data source for the tap interrupt and it is
> +	 * operating on an input data rate of 200Hz.
> +	 */
> +	if (!data->tap_event_en) {

Feels like checking the wrong thing.  If we need 200Hz, check if the
data rate is at 200Hz rather than if the tap_event is not enabled.
Obviously same result, but one seems more obvious.

Also if bma400_set_accel_output_data_rate() is effectively a noop when
the data rate is unchanged (and it should be with regmap caching) then
maybe just call it unconditionally?

This might be a nasty surprise for other users though - so if buffered
output is in use, maybe just don't allow the rate change, even if
that means not enabling tap detection.

> +		ret = bma400_set_accel_output_data_rate(data, 200, 0);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	ret = regmap_update_bits(data->regmap, BMA400_INT12_MAP_REG,
> +				 BMA400_S_TAP_MSK,
> +				 FIELD_PREP(BMA400_S_TAP_MSK, state));
> +	if (ret)
> +		return ret;
> +
> +	switch (dir) {
> +	case IIO_EV_DIR_SINGLETAP:
> +		mask = BMA400_S_TAP_MSK;
> +		set_mask_bits(&field_value, BMA400_S_TAP_MSK,
> +			      FIELD_PREP(BMA400_S_TAP_MSK, state));
> +		break;
> +	case IIO_EV_DIR_DOUBLETAP:
> +		mask = BMA400_D_TAP_MSK;
> +		set_mask_bits(&field_value, BMA400_D_TAP_MSK,
> +			      FIELD_PREP(BMA400_D_TAP_MSK, state));
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	ret = regmap_update_bits(data->regmap, BMA400_INT_CONFIG1_REG, mask,
> +				 field_value);
> +	if (ret)
> +		return ret;
> +
> +	set_mask_bits(&data->tap_event_en, mask, field_value);

blank line here

> +	return 0;
> +}
> +
> +static int bma400_disable_adv_interrupt(struct bma400_data *data)
> +{
> +	int ret;
> +
> +	ret = regmap_write(data->regmap, BMA400_INT_CONFIG0_REG, 0);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_write(data->regmap, BMA400_INT_CONFIG1_REG, 0);
> +	if (ret)
> +		return ret;
> +
> +	data->tap_event_en = 0;
> +	data->generic_event_en = 0;
> +	data->step_event_en = 0;
> +	data->activity_event_en = 0;

blank line here

> +	return 0;
> +}
> +
>  static int bma400_write_event_config(struct iio_dev *indio_dev,
>  				     const struct iio_chan_spec *chan,
>  				     enum iio_event_type type,
> @@ -1111,10 +1205,20 @@ static int bma400_write_event_config(struct iio_dev *indio_dev,
>  
>  	switch (chan->type) {
>  	case IIO_ACCEL:
> -		mutex_lock(&data->mutex);
> -		ret = bma400_activity_event_en(data, dir, state);
> -		mutex_unlock(&data->mutex);
> -		return ret;
> +		switch (type) {
> +		case IIO_EV_TYPE_MAG:
> +			mutex_lock(&data->mutex);
> +			ret = bma400_activity_event_en(data, dir, state);
> +			mutex_unlock(&data->mutex);
> +			return ret;
> +		case IIO_EV_TYPE_GESTURE:
> +			mutex_lock(&data->mutex);
> +			ret = bma400_tap_event_enable(data, dir, state);

Given existing naming event_en would seem more consistent.

> +			mutex_unlock(&data->mutex);
> +			return ret;
> +		default:
> +			return -EINVAL;
> +		}
>  	case IIO_STEPS:
>  		mutex_lock(&data->mutex);
>  		ret = bma400_steps_event_enable(data, state);
> @@ -1159,8 +1263,8 @@ static int bma400_read_event_value(struct iio_dev *indio_dev,
>  	struct bma400_data *data = iio_priv(indio_dev);
>  	int ret, reg;
>  
> -	switch (chan->type) {
> -	case IIO_ACCEL:
> +	switch (type) {
> +	case IIO_EV_TYPE_MAG:
>  		reg = get_gen_config_reg(dir);
>  		if (reg < 0)
>  			return -EINVAL;
> @@ -1196,6 +1300,25 @@ static int bma400_read_event_value(struct iio_dev *indio_dev,
>  		default:
>  			return -EINVAL;
>  		}
> +	case IIO_EV_TYPE_GESTURE:
> +		switch (info) {
> +		case IIO_EV_INFO_VALUE:
> +			ret = regmap_read(data->regmap,
> +					  BMA400_TAP_CONFIG, val);

Line wrap looks a bit premature - BMA400_TAP_CONFIG can fit on previous line.

> +			if (ret)
> +				return ret;
> +			*val = FIELD_GET(BMA400_TAP_SEN_MSK, *val);
> +			return IIO_VAL_INT;
> +		case IIO_EV_INFO_PERIOD:
> +			ret = regmap_read(data->regmap,
> +					  BMA400_TAP_CONFIG1, val);
> +			if (ret)
> +				return ret;
> +			*val = FIELD_GET(BMA400_TAP_QUITE_MSK, *val);
> +			return IIO_VAL_INT;
> +		default:
> +			return -EINVAL;
> +		}
>  	default:
>  		return -EINVAL;
>  	}
> @@ -1211,8 +1334,8 @@ static int bma400_write_event_value(struct iio_dev *indio_dev,
>  	struct bma400_data *data = iio_priv(indio_dev);
>  	int reg, ret;
>  
> -	switch (chan->type) {
> -	case IIO_ACCEL:
> +	switch (type) {
> +	case IIO_EV_TYPE_MAG:
>  		reg = get_gen_config_reg(dir);
>  		if (reg < 0)
>  			return -EINVAL;
> @@ -1228,7 +1351,6 @@ static int bma400_write_event_value(struct iio_dev *indio_dev,
>  		case IIO_EV_INFO_PERIOD:
>  			if (val < 1 || val > 65535)
>  				return -EINVAL;
> -
>  			mutex_lock(&data->mutex);
>  			put_unaligned_be16(val, &data->duration);
>  			ret = regmap_bulk_write(data->regmap,
> @@ -1248,6 +1370,30 @@ static int bma400_write_event_value(struct iio_dev *indio_dev,
>  		default:
>  			return -EINVAL;
>  		}
> +	case IIO_EV_TYPE_GESTURE:
> +		switch (info) {
> +		case IIO_EV_INFO_VALUE:
> +			if (val < 0 || val > 7)

Add an _avail for the event control perhaps?
I think we never brought those into the core code, so you'll have to do
it manually by registering the additional event attr.

There are some examples in tree such as light/tsl2591

> +				return -EINVAL;
> +
> +			return regmap_update_bits(data->regmap,
> +						  BMA400_TAP_CONFIG,
> +						  BMA400_TAP_SEN_MSK,
> +						  FIELD_PREP(BMA400_TAP_SEN_MSK,
> +							     val));
> +
> +		case IIO_EV_INFO_PERIOD:
> +			if (val < 0 || val > 3)
> +				return -EINVAL;
> +
> +			return regmap_update_bits(data->regmap,
> +						  BMA400_TAP_CONFIG1,
> +						  BMA400_TAP_QUITE_MSK,
> +						  FIELD_PREP(BMA400_TAP_QUITE_MSK,
> +							     val));
> +		default:
> +			return -EINVAL;
> +		}
>  	default:
>  		return -EINVAL;
>  	}
> @@ -1350,6 +1496,28 @@ static irqreturn_t bma400_interrupt(int irq, void *private)
>  	if (ret || !data->status)
>  		goto unlock_err;
>  
> +	/* Disable all advance interrupts if interrupt engine overrun occurs */

Add a reference, or more detail on why this is the correct action if we get
an engine overrun.

> +	if (FIELD_GET(BMA400_INT_ENG_OVRUN_MSK, le16_to_cpu(data->status))) {
> +		bma400_disable_adv_interrupt(data);
> +		dev_err(data->dev, "Interrupt engine overrun\n");
> +		goto unlock_err;
> +	}
> +
> +	if (FIELD_GET(BMA400_INT_S_TAP_MSK, le16_to_cpu(data->status)))
> +		ev_dir = IIO_EV_DIR_SINGLETAP;
> +
> +	if (FIELD_GET(BMA400_INT_D_TAP_MSK, le16_to_cpu(data->status)))

If both can occur, send two events. If not, else if

> +		ev_dir = IIO_EV_DIR_DOUBLETAP;
> +
> +	if (ev_dir != IIO_EV_DIR_NONE) {
> +		iio_push_event(indio_dev,
> +			       IIO_MOD_EVENT_CODE(IIO_ACCEL, 0,
> +						  IIO_MOD_X_OR_Y_OR_Z,
> +						  IIO_EV_TYPE_GESTURE, ev_dir),
> +			       timestamp);
> +	}
> +
> +	ev_dir = IIO_EV_DIR_NONE;
>  	if (FIELD_GET(BMA400_INT_GEN1_MSK, le16_to_cpu(data->status)))
>  		ev_dir = IIO_EV_DIR_RISING;
>  

Re: [RFC 2/2] iio: accel: bma400: Add support for single and double tap events

[Jagath Jog J]

Hi Jonathan and Andy.

On Sat, Jun 4, 2022 at 8:22 PM Jonathan Cameron <jic23@kernel.org> wrote:
>
> On Sun, 29 May 2022 09:31:53 +0530
> Jagath Jog J <jagathjog1996@gmail.com> wrote:
>
> > Add support for single and double tap events based on the tap threshold
> > value and minimum quite time value between the taps. INT1 pin is used to
> > interrupt and event is pushed to userspace.
> >
> > Signed-off-by: Jagath Jog J <jagathjog1996@gmail.com>
>
> Hi Jagath,
>
> A few comments inline.
>
> Thanks,
>
> Jonathan
>
> > ---
> >  drivers/iio/accel/bma400.h      |  11 ++
> >  drivers/iio/accel/bma400_core.c | 186 ++++++++++++++++++++++++++++++--
> >  2 files changed, 188 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/iio/accel/bma400.h b/drivers/iio/accel/bma400.h
> > index e8f802a82300..7331474433fa 100644
> > --- a/drivers/iio/accel/bma400.h
> > +++ b/drivers/iio/accel/bma400.h
> > @@ -40,6 +40,7 @@
> >  #define BMA400_INT_STAT1_REG        0x0f
> >  #define BMA400_INT_STAT2_REG        0x10
> >  #define BMA400_INT12_MAP_REG        0x23
> > +#define BMA400_INT_ENG_OVRUN_MSK    BIT(4)
> >
> >  /* Temperature register */
> >  #define BMA400_TEMP_DATA_REG        0x11
> > @@ -105,6 +106,16 @@
> >  #define BMA400_INT_GEN2_MSK         BIT(3)
> >  #define BMA400_GEN_HYST_MSK         GENMASK(1, 0)
> >
> > +/* TAP config registers */
> > +#define BMA400_TAP_CONFIG           0x57
> > +#define BMA400_TAP_CONFIG1          0x58
> > +#define BMA400_S_TAP_MSK            BIT(2)
> > +#define BMA400_D_TAP_MSK            BIT(3)
> > +#define BMA400_INT_S_TAP_MSK        BIT(10)
> > +#define BMA400_INT_D_TAP_MSK        BIT(11)
> > +#define BMA400_TAP_SEN_MSK          GENMASK(2, 0)
> > +#define BMA400_TAP_QUITE_MSK        GENMASK(3, 2)

Andy, I will correct this QUITE in the next patch version.

> > +
> >  /*
> >   * BMA400_SCALE_MIN macro value represents m/s^2 for 1 LSB before
> >   * converting to micro values for +-2g range.
> > diff --git a/drivers/iio/accel/bma400_core.c b/drivers/iio/accel/bma400_core.c
> > index 517920400df1..2385883707f2 100644
> > --- a/drivers/iio/accel/bma400_core.c
> > +++ b/drivers/iio/accel/bma400_core.c
> > @@ -88,6 +88,7 @@ struct bma400_data {
> >       bool step_event_en;
> >       bool activity_event_en;
> >       unsigned int generic_event_en;
> > +     unsigned int tap_event_en;
> >       /* Correct time stamp alignment */
> >       struct {
> >               __le16 buff[3];
> > @@ -216,6 +217,19 @@ static const struct iio_event_spec bma400_accel_event[] = {
> >                                      BIT(IIO_EV_INFO_HYSTERESIS) |
> >                                      BIT(IIO_EV_INFO_ENABLE),
> >       },
> > +     {
> > +             .type = IIO_EV_TYPE_GESTURE,
> > +             .dir = IIO_EV_DIR_SINGLETAP,
> > +             .mask_shared_by_type = BIT(IIO_EV_INFO_VALUE) |
> > +                                    BIT(IIO_EV_INFO_ENABLE),
> > +     },
> > +     {
> > +             .type = IIO_EV_TYPE_GESTURE,
> > +             .dir = IIO_EV_DIR_DOUBLETAP,
> > +             .mask_shared_by_type = BIT(IIO_EV_INFO_VALUE) |
> > +                                    BIT(IIO_EV_INFO_PERIOD) |
>
> Feels like period isn't well defined for this case.  So probably needs a specific
> ABI entry and period might not be best choice...  However, period has no logical
> other meaning in this case (what does 'amount of time a double tap has been true for before
> event mean?') so I think it is fine to use it, as long as ABI docs exist to say what it's
> meaning is for this case.

I will add ABI docs for the period.

>
> > +                                    BIT(IIO_EV_INFO_ENABLE),
> > +     },
> >  };
> >
> >  #define BMA400_ACC_CHANNEL(_index, _axis) { \
> > @@ -407,6 +421,14 @@ static int bma400_set_accel_output_data_rate(struct bma400_data *data,
> >       unsigned int val;
> >       int ret;
> >
> > +     /*
> > +      * No need to change ODR when tap event is enabled because
>
> Do not change ODR...
>
>
> > +      * tap interrupt is operating with the data rate of 200Hz.
> > +      * See datasheet page 124.

I will update this with the proper datasheet section details.

> > +      */
> > +     if (data->tap_event_en)
> > +             return -EBUSY;
> > +
> >       if (hz >= BMA400_ACC_ODR_MIN_WHOLE_HZ) {
> >               if (uhz || hz > BMA400_ACC_ODR_MAX_HZ)
> >                       return -EINVAL;
> > @@ -1012,6 +1034,10 @@ static int bma400_read_event_config(struct iio_dev *indio_dev,
> >               case IIO_EV_DIR_FALLING:
> >                       return FIELD_GET(BMA400_INT_GEN2_MSK,
> >                                        data->generic_event_en);
> > +             case IIO_EV_DIR_SINGLETAP:
> > +                     return FIELD_GET(BMA400_S_TAP_MSK, data->tap_event_en);
> > +             case IIO_EV_DIR_DOUBLETAP:
> > +                     return FIELD_GET(BMA400_D_TAP_MSK, data->tap_event_en);
> >               default:
> >                       return -EINVAL;
> >               }
> > @@ -1101,6 +1127,74 @@ static int bma400_activity_event_en(struct bma400_data *data,
> >       return 0;
> >  }
> >
> > +static int bma400_tap_event_enable(struct bma400_data *data,
> > +                                enum iio_event_direction dir, int state)
> > +{
> > +     int ret;
> > +     unsigned int mask, field_value;
> > +
> > +     if (data->power_mode == POWER_MODE_SLEEP)
> > +             return -EBUSY;
>
> There are existing examples of this in driver, but I can't immediately
> see how we end up in sleep mode.  Perhaps a comment on why this might happen?
>
> > +
> > +     /*
> > +      * acc_filt1 is the data source for the tap interrupt and it is
> > +      * operating on an input data rate of 200Hz.
> > +      */
> > +     if (!data->tap_event_en) {
>
> Feels like checking the wrong thing.  If we need 200Hz, check if the
> data rate is at 200Hz rather than if the tap_event is not enabled.
> Obviously same result, but one seems more obvious.

if (!data->tap_event_en)
This checking is to make sure not to execute
bma400_set_accel_output_data_rate() function while disabling the
tap event to avoid the negative (-EBUSY) return value from the
function bma400_set_accel_output_data_rate() when either of
the tap is enabled.

>
> Also if bma400_set_accel_output_data_rate() is effectively a noop when
> the data rate is unchanged (and it should be with regmap caching) then
> maybe just call it unconditionally?
>
> This might be a nasty surprise for other users though - so if buffered
> output is in use, maybe just don't allow the rate change, even if
> that means not enabling tap detection.
>
> > +             ret = bma400_set_accel_output_data_rate(data, 200, 0);
> > +             if (ret)
> > +                     return ret;
> > +     }
> > +
> > +     ret = regmap_update_bits(data->regmap, BMA400_INT12_MAP_REG,
> > +                              BMA400_S_TAP_MSK,
> > +                              FIELD_PREP(BMA400_S_TAP_MSK, state));
> > +     if (ret)
> > +             return ret;
> > +
> > +     switch (dir) {
> > +     case IIO_EV_DIR_SINGLETAP:
> > +             mask = BMA400_S_TAP_MSK;
> > +             set_mask_bits(&field_value, BMA400_S_TAP_MSK,
> > +                           FIELD_PREP(BMA400_S_TAP_MSK, state));
> > +             break;
> > +     case IIO_EV_DIR_DOUBLETAP:
> > +             mask = BMA400_D_TAP_MSK;
> > +             set_mask_bits(&field_value, BMA400_D_TAP_MSK,
> > +                           FIELD_PREP(BMA400_D_TAP_MSK, state));
> > +             break;
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +
> > +     ret = regmap_update_bits(data->regmap, BMA400_INT_CONFIG1_REG, mask,
> > +                              field_value);
> > +     if (ret)
> > +             return ret;
> > +
> > +     set_mask_bits(&data->tap_event_en, mask, field_value);
>
> blank line here
>
> > +     return 0;
> > +}
> > +
> > +static int bma400_disable_adv_interrupt(struct bma400_data *data)
> > +{
> > +     int ret;
> > +
> > +     ret = regmap_write(data->regmap, BMA400_INT_CONFIG0_REG, 0);
> > +     if (ret)
> > +             return ret;
> > +
> > +     ret = regmap_write(data->regmap, BMA400_INT_CONFIG1_REG, 0);
> > +     if (ret)
> > +             return ret;
> > +
> > +     data->tap_event_en = 0;
> > +     data->generic_event_en = 0;
> > +     data->step_event_en = 0;
> > +     data->activity_event_en = 0;
>
> blank line here
>
> > +     return 0;
> > +}
> > +
> >  static int bma400_write_event_config(struct iio_dev *indio_dev,
> >                                    const struct iio_chan_spec *chan,
> >                                    enum iio_event_type type,
> > @@ -1111,10 +1205,20 @@ static int bma400_write_event_config(struct iio_dev *indio_dev,
> >
> >       switch (chan->type) {
> >       case IIO_ACCEL:
> > -             mutex_lock(&data->mutex);
> > -             ret = bma400_activity_event_en(data, dir, state);
> > -             mutex_unlock(&data->mutex);
> > -             return ret;
> > +             switch (type) {
> > +             case IIO_EV_TYPE_MAG:
> > +                     mutex_lock(&data->mutex);
> > +                     ret = bma400_activity_event_en(data, dir, state);
> > +                     mutex_unlock(&data->mutex);
> > +                     return ret;
> > +             case IIO_EV_TYPE_GESTURE:
> > +                     mutex_lock(&data->mutex);
> > +                     ret = bma400_tap_event_enable(data, dir, state);
>
> Given existing naming event_en would seem more consistent.
>
> > +                     mutex_unlock(&data->mutex);
> > +                     return ret;
> > +             default:
> > +                     return -EINVAL;
> > +             }
> >       case IIO_STEPS:
> >               mutex_lock(&data->mutex);
> >               ret = bma400_steps_event_enable(data, state);
> > @@ -1159,8 +1263,8 @@ static int bma400_read_event_value(struct iio_dev *indio_dev,
> >       struct bma400_data *data = iio_priv(indio_dev);
> >       int ret, reg;
> >
> > -     switch (chan->type) {
> > -     case IIO_ACCEL:
> > +     switch (type) {
> > +     case IIO_EV_TYPE_MAG:
> >               reg = get_gen_config_reg(dir);
> >               if (reg < 0)
> >                       return -EINVAL;
> > @@ -1196,6 +1300,25 @@ static int bma400_read_event_value(struct iio_dev *indio_dev,
> >               default:
> >                       return -EINVAL;
> >               }
> > +     case IIO_EV_TYPE_GESTURE:
> > +             switch (info) {
> > +             case IIO_EV_INFO_VALUE:
> > +                     ret = regmap_read(data->regmap,
> > +                                       BMA400_TAP_CONFIG, val);
>
> Line wrap looks a bit premature - BMA400_TAP_CONFIG can fit on previous line.
>
> > +                     if (ret)
> > +                             return ret;
> > +                     *val = FIELD_GET(BMA400_TAP_SEN_MSK, *val);
> > +                     return IIO_VAL_INT;
> > +             case IIO_EV_INFO_PERIOD:
> > +                     ret = regmap_read(data->regmap,
> > +                                       BMA400_TAP_CONFIG1, val);
> > +                     if (ret)
> > +                             return ret;
> > +                     *val = FIELD_GET(BMA400_TAP_QUITE_MSK, *val);
> > +                     return IIO_VAL_INT;
> > +             default:
> > +                     return -EINVAL;
> > +             }
> >       default:
> >               return -EINVAL;
> >       }
> > @@ -1211,8 +1334,8 @@ static int bma400_write_event_value(struct iio_dev *indio_dev,
> >       struct bma400_data *data = iio_priv(indio_dev);
> >       int reg, ret;
> >
> > -     switch (chan->type) {
> > -     case IIO_ACCEL:
> > +     switch (type) {
> > +     case IIO_EV_TYPE_MAG:
> >               reg = get_gen_config_reg(dir);
> >               if (reg < 0)
> >                       return -EINVAL;
> > @@ -1228,7 +1351,6 @@ static int bma400_write_event_value(struct iio_dev *indio_dev,
> >               case IIO_EV_INFO_PERIOD:
> >                       if (val < 1 || val > 65535)
> >                               return -EINVAL;
> > -
> >                       mutex_lock(&data->mutex);
> >                       put_unaligned_be16(val, &data->duration);
> >                       ret = regmap_bulk_write(data->regmap,
> > @@ -1248,6 +1370,30 @@ static int bma400_write_event_value(struct iio_dev *indio_dev,
> >               default:
> >                       return -EINVAL;
> >               }
> > +     case IIO_EV_TYPE_GESTURE:
> > +             switch (info) {
> > +             case IIO_EV_INFO_VALUE:
> > +                     if (val < 0 || val > 7)
>
> Add an _avail for the event control perhaps?
> I think we never brought those into the core code, so you'll have to do
> it manually by registering the additional event attr.
>
> There are some examples in tree such as light/tsl2591

Thanks for the suggestion I will add _avail for value and also
I will address other comments in the next patch.

>
> > +                             return -EINVAL;
> > +
> > +                     return regmap_update_bits(data->regmap,
> > +                                               BMA400_TAP_CONFIG,
> > +                                               BMA400_TAP_SEN_MSK,
> > +                                               FIELD_PREP(BMA400_TAP_SEN_MSK,
> > +                                                          val));
> > +
> > +             case IIO_EV_INFO_PERIOD:
> > +                     if (val < 0 || val > 3)
> > +                             return -EINVAL;
> > +
> > +                     return regmap_update_bits(data->regmap,
> > +                                               BMA400_TAP_CONFIG1,
> > +                                               BMA400_TAP_QUITE_MSK,
> > +                                               FIELD_PREP(BMA400_TAP_QUITE_MSK,
> > +                                                          val));
> > +             default:
> > +                     return -EINVAL;
> > +             }
> >       default:
> >               return -EINVAL;
> >       }
> > @@ -1350,6 +1496,28 @@ static irqreturn_t bma400_interrupt(int irq, void *private)
> >       if (ret || !data->status)
> >               goto unlock_err;
> >
> > +     /* Disable all advance interrupts if interrupt engine overrun occurs */
>
> Add a reference, or more detail on why this is the correct action if we get
> an engine overrun.
>
> > +     if (FIELD_GET(BMA400_INT_ENG_OVRUN_MSK, le16_to_cpu(data->status))) {
> > +             bma400_disable_adv_interrupt(data);
> > +             dev_err(data->dev, "Interrupt engine overrun\n");
> > +             goto unlock_err;
> > +     }
> > +
> > +     if (FIELD_GET(BMA400_INT_S_TAP_MSK, le16_to_cpu(data->status)))
> > +             ev_dir = IIO_EV_DIR_SINGLETAP;
> > +
> > +     if (FIELD_GET(BMA400_INT_D_TAP_MSK, le16_to_cpu(data->status)))
>
> If both can occur, send two events. If not, else if
>
> > +             ev_dir = IIO_EV_DIR_DOUBLETAP;
> > +
> > +     if (ev_dir != IIO_EV_DIR_NONE) {
> > +             iio_push_event(indio_dev,
> > +                            IIO_MOD_EVENT_CODE(IIO_ACCEL, 0,
> > +                                               IIO_MOD_X_OR_Y_OR_Z,
> > +                                               IIO_EV_TYPE_GESTURE, ev_dir),
> > +                            timestamp);
> > +     }
> > +
> > +     ev_dir = IIO_EV_DIR_NONE;
> >       if (FIELD_GET(BMA400_INT_GEN1_MSK, le16_to_cpu(data->status)))
> >               ev_dir = IIO_EV_DIR_RISING;
> >
>

Re: [RFC 2/2] iio: accel: bma400: Add support for single and double tap events

[Jonathan Cameron]

On Sun, 5 Jun 2022 10:38:10 +0530
Jagath Jog J <jagathjog1996@gmail.com> wrote:

> Hi Jonathan and Andy.
> 
> On Sat, Jun 4, 2022 at 8:22 PM Jonathan Cameron <jic23@kernel.org> wrote:
> >
> > On Sun, 29 May 2022 09:31:53 +0530
> > Jagath Jog J <jagathjog1996@gmail.com> wrote:
> >  
> > > Add support for single and double tap events based on the tap threshold
> > > value and minimum quite time value between the taps. INT1 pin is used to
> > > interrupt and event is pushed to userspace.
> > >
> > > Signed-off-by: Jagath Jog J <jagathjog1996@gmail.com>  
> >
> > Hi Jagath,
> >
> > A few comments inline.
> >
> > Thanks,
> >
> > Jonathan



> > > +
> > > +     /*
> > > +      * acc_filt1 is the data source for the tap interrupt and it is
> > > +      * operating on an input data rate of 200Hz.
> > > +      */
> > > +     if (!data->tap_event_en) {  
> >
> > Feels like checking the wrong thing.  If we need 200Hz, check if the
> > data rate is at 200Hz rather than if the tap_event is not enabled.
> > Obviously same result, but one seems more obvious.  
> 
> if (!data->tap_event_en)
> This checking is to make sure not to execute
> bma400_set_accel_output_data_rate() function while disabling the
> tap event to avoid the negative (-EBUSY) return value from the
> function bma400_set_accel_output_data_rate() when either of
> the tap is enabled.

Ah. Fair enough. It's a little odd looking though. You could push
the check out of bma400_set_accel_output_data_rate() and into
write_raw though would need to be within the lock to avoid potential
race conditions.  Perhaps just not worth the effort.

Jonathan

Re: [RFC 2/2] iio: accel: bma400: Add support for single and double tap events

[Jagath Jog J]

 Hi Jonathan,

On Sat, Jun 4, 2022 at 8:22 PM Jonathan Cameron <jic23@kernel.org> wrote:
>
> On Sun, 29 May 2022 09:31:53 +0530
> Jagath Jog J <jagathjog1996@gmail.com> wrote:
>
> > Add support for single and double tap events based on the tap threshold
> > value and minimum quite time value between the taps. INT1 pin is used to
> > interrupt and event is pushed to userspace.
> >
> > Signed-off-by: Jagath Jog J <jagathjog1996@gmail.com>
>
> Hi Jagath,
>
> A few comments inline.
>
> Thanks,
>
> Jonathan
>
> > ---
> >  drivers/iio/accel/bma400.h      |  11 ++
> >  drivers/iio/accel/bma400_core.c | 186 ++++++++++++++++++++++++++++++--
> >  2 files changed, 188 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/iio/accel/bma400.h b/drivers/iio/accel/bma400.h
> > index e8f802a82300..7331474433fa 100644
> > --- a/drivers/iio/accel/bma400.h
> > +++ b/drivers/iio/accel/bma400.h
> > @@ -40,6 +40,7 @@
> >  #define BMA400_INT_STAT1_REG        0x0f
> >  #define BMA400_INT_STAT2_REG        0x10
> >  #define BMA400_INT12_MAP_REG        0x23
> > +#define BMA400_INT_ENG_OVRUN_MSK    BIT(4)
> >
> >  /* Temperature register */
> >  #define BMA400_TEMP_DATA_REG        0x11
> > @@ -105,6 +106,16 @@
> >  #define BMA400_INT_GEN2_MSK         BIT(3)
> >  #define BMA400_GEN_HYST_MSK         GENMASK(1, 0)
> >
> > +/* TAP config registers */
> > +#define BMA400_TAP_CONFIG           0x57
> > +#define BMA400_TAP_CONFIG1          0x58
> > +#define BMA400_S_TAP_MSK            BIT(2)
> > +#define BMA400_D_TAP_MSK            BIT(3)
> > +#define BMA400_INT_S_TAP_MSK        BIT(10)
> > +#define BMA400_INT_D_TAP_MSK        BIT(11)
> > +#define BMA400_TAP_SEN_MSK          GENMASK(2, 0)
> > +#define BMA400_TAP_QUITE_MSK        GENMASK(3, 2)
> > +
> >  /*
> >   * BMA400_SCALE_MIN macro value represents m/s^2 for 1 LSB before
> >   * converting to micro values for +-2g range.
> > diff --git a/drivers/iio/accel/bma400_core.c b/drivers/iio/accel/bma400_core.c
> > index 517920400df1..2385883707f2 100644
> > --- a/drivers/iio/accel/bma400_core.c
> > +++ b/drivers/iio/accel/bma400_core.c
> > @@ -88,6 +88,7 @@ struct bma400_data {
> >       bool step_event_en;
> >       bool activity_event_en;
> >       unsigned int generic_event_en;
> > +     unsigned int tap_event_en;
> >       /* Correct time stamp alignment */
> >       struct {
> >               __le16 buff[3];
> > @@ -216,6 +217,19 @@ static const struct iio_event_spec bma400_accel_event[] = {
> >                                      BIT(IIO_EV_INFO_HYSTERESIS) |
> >                                      BIT(IIO_EV_INFO_ENABLE),
> >       },
> > +     {
> > +             .type = IIO_EV_TYPE_GESTURE,
> > +             .dir = IIO_EV_DIR_SINGLETAP,
> > +             .mask_shared_by_type = BIT(IIO_EV_INFO_VALUE) |
> > +                                    BIT(IIO_EV_INFO_ENABLE),
> > +     },
> > +     {
> > +             .type = IIO_EV_TYPE_GESTURE,
> > +             .dir = IIO_EV_DIR_DOUBLETAP,
> > +             .mask_shared_by_type = BIT(IIO_EV_INFO_VALUE) |
> > +                                    BIT(IIO_EV_INFO_PERIOD) |
>
> Feels like period isn't well defined for this case.  So probably needs a specific
> ABI entry and period might not be best choice...  However, period has no logical
> other meaning in this case (what does 'amount of time a double tap has been true for before
> event mean?') so I think it is fine to use it, as long as ABI docs exist to say what it's
> meaning is for this case.
>
> > +                                    BIT(IIO_EV_INFO_ENABLE),
> > +     },
> >  };
> >
> >  #define BMA400_ACC_CHANNEL(_index, _axis) { \
> > @@ -407,6 +421,14 @@ static int bma400_set_accel_output_data_rate(struct bma400_data *data,
> >       unsigned int val;
> >       int ret;
> >
> > +     /*
> > +      * No need to change ODR when tap event is enabled because
>
> Do not change ODR...
>
>
> > +      * tap interrupt is operating with the data rate of 200Hz.
> > +      * See datasheet page 124.
> > +      */
> > +     if (data->tap_event_en)
> > +             return -EBUSY;
> > +
> >       if (hz >= BMA400_ACC_ODR_MIN_WHOLE_HZ) {
> >               if (uhz || hz > BMA400_ACC_ODR_MAX_HZ)
> >                       return -EINVAL;
> > @@ -1012,6 +1034,10 @@ static int bma400_read_event_config(struct iio_dev *indio_dev,
> >               case IIO_EV_DIR_FALLING:
> >                       return FIELD_GET(BMA400_INT_GEN2_MSK,
> >                                        data->generic_event_en);
> > +             case IIO_EV_DIR_SINGLETAP:
> > +                     return FIELD_GET(BMA400_S_TAP_MSK, data->tap_event_en);
> > +             case IIO_EV_DIR_DOUBLETAP:
> > +                     return FIELD_GET(BMA400_D_TAP_MSK, data->tap_event_en);
> >               default:
> >                       return -EINVAL;
> >               }
> > @@ -1101,6 +1127,74 @@ static int bma400_activity_event_en(struct bma400_data *data,
> >       return 0;
> >  }
> >
> > +static int bma400_tap_event_enable(struct bma400_data *data,
> > +                                enum iio_event_direction dir, int state)
> > +{
> > +     int ret;
> > +     unsigned int mask, field_value;
> > +
> > +     if (data->power_mode == POWER_MODE_SLEEP)
> > +             return -EBUSY;
>
> There are existing examples of this in driver, but I can't immediately
> see how we end up in sleep mode.  Perhaps a comment on why this might happen?

Currently, only during the driver unwinding the device is put into sleep mode.
I should be checking whether the device is in normal mode or not since
the tap interrupts only in normal mode. I will change this.

>
> > +
> > +     /*
> > +      * acc_filt1 is the data source for the tap interrupt and it is
> > +      * operating on an input data rate of 200Hz.
> > +      */
> > +     if (!data->tap_event_en) {
>
> Feels like checking the wrong thing.  If we need 200Hz, check if the
> data rate is at 200Hz rather than if the tap_event is not enabled.
> Obviously same result, but one seems more obvious.

if (!data->tap_event_en)
As I mentioned in the previous mail this checking is to make sure
not to execute bma400_set_accel_output_data_rate() function
while disabling the tap event.

>
> Also if bma400_set_accel_output_data_rate() is effectively a noop when
> the data rate is unchanged (and it should be with regmap caching) then
> maybe just call it unconditionally?
>
> This might be a nasty surprise for other users though - so if buffered
> output is in use, maybe just don't allow the rate change, even if
> that means not enabling tap detection.

In this case, if the tap is enabled before the buffer do I need to disable
the tap events before enabling buffer?
I have tested tap events with continuous trigger buffer read but only
thing is, it is not possible to change the data rate.

Thanks,
Jagath

Re: [RFC 2/2] iio: accel: bma400: Add support for single and double tap events

[Jonathan Cameron]

On Wed, 8 Jun 2022 00:14:08 +0530
Jagath Jog J <jagathjog1996@gmail.com> wrote:

>  Hi Jonathan,
> 
> On Sat, Jun 4, 2022 at 8:22 PM Jonathan Cameron <jic23@kernel.org> wrote:
> >
> > On Sun, 29 May 2022 09:31:53 +0530
> > Jagath Jog J <jagathjog1996@gmail.com> wrote:
> >  
> > > Add support for single and double tap events based on the tap threshold
> > > value and minimum quite time value between the taps. INT1 pin is used to
> > > interrupt and event is pushed to userspace.
> > >
> > > Signed-off-by: Jagath Jog J <jagathjog1996@gmail.com>  
> >
> > Hi Jagath,
> >
> > A few comments inline.
> >
> > Thanks,
> >
> > Jonathan
> >  
> > > ---
> > >  drivers/iio/accel/bma400.h      |  11 ++
> > >  drivers/iio/accel/bma400_core.c | 186 ++++++++++++++++++++++++++++++--
> > >  2 files changed, 188 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/drivers/iio/accel/bma400.h b/drivers/iio/accel/bma400.h
> > > index e8f802a82300..7331474433fa 100644
> > > --- a/drivers/iio/accel/bma400.h
> > > +++ b/drivers/iio/accel/bma400.h
> > > @@ -40,6 +40,7 @@
> > >  #define BMA400_INT_STAT1_REG        0x0f
> > >  #define BMA400_INT_STAT2_REG        0x10
> > >  #define BMA400_INT12_MAP_REG        0x23
> > > +#define BMA400_INT_ENG_OVRUN_MSK    BIT(4)
> > >
> > >  /* Temperature register */
> > >  #define BMA400_TEMP_DATA_REG        0x11
> > > @@ -105,6 +106,16 @@
> > >  #define BMA400_INT_GEN2_MSK         BIT(3)
> > >  #define BMA400_GEN_HYST_MSK         GENMASK(1, 0)
> > >
> > > +/* TAP config registers */
> > > +#define BMA400_TAP_CONFIG           0x57
> > > +#define BMA400_TAP_CONFIG1          0x58
> > > +#define BMA400_S_TAP_MSK            BIT(2)
> > > +#define BMA400_D_TAP_MSK            BIT(3)
> > > +#define BMA400_INT_S_TAP_MSK        BIT(10)
> > > +#define BMA400_INT_D_TAP_MSK        BIT(11)
> > > +#define BMA400_TAP_SEN_MSK          GENMASK(2, 0)
> > > +#define BMA400_TAP_QUITE_MSK        GENMASK(3, 2)
> > > +
> > >  /*
> > >   * BMA400_SCALE_MIN macro value represents m/s^2 for 1 LSB before
> > >   * converting to micro values for +-2g range.
> > > diff --git a/drivers/iio/accel/bma400_core.c b/drivers/iio/accel/bma400_core.c
> > > index 517920400df1..2385883707f2 100644
> > > --- a/drivers/iio/accel/bma400_core.c
> > > +++ b/drivers/iio/accel/bma400_core.c
> > > @@ -88,6 +88,7 @@ struct bma400_data {
> > >       bool step_event_en;
> > >       bool activity_event_en;
> > >       unsigned int generic_event_en;
> > > +     unsigned int tap_event_en;
> > >       /* Correct time stamp alignment */
> > >       struct {
> > >               __le16 buff[3];
> > > @@ -216,6 +217,19 @@ static const struct iio_event_spec bma400_accel_event[] = {
> > >                                      BIT(IIO_EV_INFO_HYSTERESIS) |
> > >                                      BIT(IIO_EV_INFO_ENABLE),
> > >       },
> > > +     {
> > > +             .type = IIO_EV_TYPE_GESTURE,
> > > +             .dir = IIO_EV_DIR_SINGLETAP,
> > > +             .mask_shared_by_type = BIT(IIO_EV_INFO_VALUE) |
> > > +                                    BIT(IIO_EV_INFO_ENABLE),
> > > +     },
> > > +     {
> > > +             .type = IIO_EV_TYPE_GESTURE,
> > > +             .dir = IIO_EV_DIR_DOUBLETAP,
> > > +             .mask_shared_by_type = BIT(IIO_EV_INFO_VALUE) |
> > > +                                    BIT(IIO_EV_INFO_PERIOD) |  
> >
> > Feels like period isn't well defined for this case.  So probably needs a specific
> > ABI entry and period might not be best choice...  However, period has no logical
> > other meaning in this case (what does 'amount of time a double tap has been true for before
> > event mean?') so I think it is fine to use it, as long as ABI docs exist to say what it's
> > meaning is for this case.
> >  
> > > +                                    BIT(IIO_EV_INFO_ENABLE),
> > > +     },
> > >  };
> > >
> > >  #define BMA400_ACC_CHANNEL(_index, _axis) { \
> > > @@ -407,6 +421,14 @@ static int bma400_set_accel_output_data_rate(struct bma400_data *data,
> > >       unsigned int val;
> > >       int ret;
> > >
> > > +     /*
> > > +      * No need to change ODR when tap event is enabled because  
> >
> > Do not change ODR...
> >
> >  
> > > +      * tap interrupt is operating with the data rate of 200Hz.
> > > +      * See datasheet page 124.
> > > +      */
> > > +     if (data->tap_event_en)
> > > +             return -EBUSY;
> > > +
> > >       if (hz >= BMA400_ACC_ODR_MIN_WHOLE_HZ) {
> > >               if (uhz || hz > BMA400_ACC_ODR_MAX_HZ)
> > >                       return -EINVAL;
> > > @@ -1012,6 +1034,10 @@ static int bma400_read_event_config(struct iio_dev *indio_dev,
> > >               case IIO_EV_DIR_FALLING:
> > >                       return FIELD_GET(BMA400_INT_GEN2_MSK,
> > >                                        data->generic_event_en);
> > > +             case IIO_EV_DIR_SINGLETAP:
> > > +                     return FIELD_GET(BMA400_S_TAP_MSK, data->tap_event_en);
> > > +             case IIO_EV_DIR_DOUBLETAP:
> > > +                     return FIELD_GET(BMA400_D_TAP_MSK, data->tap_event_en);
> > >               default:
> > >                       return -EINVAL;
> > >               }
> > > @@ -1101,6 +1127,74 @@ static int bma400_activity_event_en(struct bma400_data *data,
> > >       return 0;
> > >  }
> > >
> > > +static int bma400_tap_event_enable(struct bma400_data *data,
> > > +                                enum iio_event_direction dir, int state)
> > > +{
> > > +     int ret;
> > > +     unsigned int mask, field_value;
> > > +
> > > +     if (data->power_mode == POWER_MODE_SLEEP)
> > > +             return -EBUSY;  
> >
> > There are existing examples of this in driver, but I can't immediately
> > see how we end up in sleep mode.  Perhaps a comment on why this might happen?  
> 
> Currently, only during the driver unwinding the device is put into sleep mode.
> I should be checking whether the device is in normal mode or not since
> the tap interrupts only in normal mode. I will change this.
> 
> >  
> > > +
> > > +     /*
> > > +      * acc_filt1 is the data source for the tap interrupt and it is
> > > +      * operating on an input data rate of 200Hz.
> > > +      */
> > > +     if (!data->tap_event_en) {  
> >
> > Feels like checking the wrong thing.  If we need 200Hz, check if the
> > data rate is at 200Hz rather than if the tap_event is not enabled.
> > Obviously same result, but one seems more obvious.  
> 
> if (!data->tap_event_en)
> As I mentioned in the previous mail this checking is to make sure
> not to execute bma400_set_accel_output_data_rate() function
> while disabling the tap event.
Add more to the comment.  I'll think a bit more on this in next version.
> 
> >
> > Also if bma400_set_accel_output_data_rate() is effectively a noop when
> > the data rate is unchanged (and it should be with regmap caching) then
> > maybe just call it unconditionally?
> >
> > This might be a nasty surprise for other users though - so if buffered
> > output is in use, maybe just don't allow the rate change, even if
> > that means not enabling tap detection.  
> 
> In this case, if the tap is enabled before the buffer do I need to disable
> the tap events before enabling buffer?
> I have tested tap events with continuous trigger buffer read but only
> thing is, it is not possible to change the data rate.
Another option is to just fail the buffer start if if a different frequency
is requested or fail to start the tap detection in the first place
if sampling_frequency isn't set correctly.  (spit out a message to the
log though as it's a bit of an odd corner case!)

Jonathan

> 
> Thanks,
> Jagath