Re: [PATCH V2 3/8] iio: mma8452: Basic support for transient events.

[Jonathan Cameron <jic23@kernel.org>]

On 29/07/14 10:01, Martin Fuzzey wrote:
> The event is triggered when the highpass filtered absolute acceleration
> exceeds the threshold.
>
> Signed-off-by: Martin Fuzzey <mfuzzey@parkeon.com>
I am unsure of the best way to handle this high pass filtered threshold.
Suggestions inline.  I'm not happy just throwing it through the
current interface and ignoring the filter...

J
> ---
>  drivers/iio/accel/mma8452.c |  203 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 202 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
> index c46df4e..3415b36 100644
> --- a/drivers/iio/accel/mma8452.c
> +++ b/drivers/iio/accel/mma8452.c
> @@ -9,7 +9,7 @@
>   *
>   * 7-bit I2C slave address 0x1c/0x1d (pin selectable)
>   *
> - * TODO: interrupt, thresholding, orientation / freefall events, autosleep
> + * TODO: orientation / freefall events, autosleep
>   */
>
>  #include <linux/module.h>
> @@ -19,20 +19,33 @@
>  #include <linux/iio/trigger_consumer.h>
>  #include <linux/iio/buffer.h>
>  #include <linux/iio/triggered_buffer.h>
> +#include <linux/iio/events.h>
>  #include <linux/delay.h>
>
>  #define MMA8452_STATUS 0x00
>  #define MMA8452_OUT_X 0x01 /* MSB first, 12-bit  */
>  #define MMA8452_OUT_Y 0x03
>  #define MMA8452_OUT_Z 0x05
> +#define MMA8452_INT_SRC 0x0c
>  #define MMA8452_WHO_AM_I 0x0d
>  #define MMA8452_DATA_CFG 0x0e
> +#define MMA8452_TRANSIENT_CFG 0x1d
> +#define MMA8452_TRANSIENT_CFG_ELE		BIT(4)
> +#define MMA8452_TRANSIENT_CFG_CHAN_MASK(chan)	(BIT(1) << chan)
> +#define MMA8452_TRANSIENT_SRC 0x1e
> +#define MMA8452_TRANSIENT_SRC_XTRANSE		BIT(1)
> +#define MMA8452_TRANSIENT_SRC_YTRANSE		BIT(3)
> +#define MMA8452_TRANSIENT_SRC_ZTRANSE		BIT(5)
> +#define MMA8452_TRANSIENT_THS 0x1f
> +#define MMA8452_TRANSIENT_COUNT 0x20
>  #define MMA8452_OFF_X 0x2f
>  #define MMA8452_OFF_Y 0x30
>  #define MMA8452_OFF_Z 0x31
>  #define MMA8452_CTRL_REG1 0x2a
>  #define MMA8452_CTRL_REG2 0x2b
>  #define MMA8452_CTRL_REG2_RST		BIT(6)
> +#define MMA8452_CTRL_REG4 0x2d
> +#define MMA8452_CTRL_REG5 0x2e
>
>  #define MMA8452_MAX_REG 0x31
>
> @@ -48,6 +61,13 @@
>  #define MMA8452_DATA_CFG_FS_4G 1
>  #define MMA8452_DATA_CFG_FS_8G 2
>
> +#define MMA8452_INT_DRDY	BIT(0)
> +#define MMA8452_INT_FF_MT	BIT(2)
> +#define MMA8452_INT_PULSE	BIT(3)
> +#define MMA8452_INT_LNDPRT	BIT(4)
> +#define MMA8452_INT_TRANS	BIT(5)
> +#define MMA8452_INT_ASLP	BIT(7)
> +
>  #define MMA8452_DEVICE_ID 0x2a
>
>  struct mma8452_data {
> @@ -274,6 +294,117 @@ static int mma8452_write_raw(struct iio_dev *indio_dev,
>  	}
>  }
>
> +static int mma8452_read_thresh(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)
> +{
> +	struct mma8452_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	ret = i2c_smbus_read_byte_data(data->client, MMA8452_TRANSIENT_THS);
> +	if (ret < 0)
> +		return ret;
> +
> +	*val = ret & 0x7f;
> +
> +	return IIO_VAL_INT;
> +}
> +
> +static int mma8452_write_thresh(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)
> +{
> +	struct mma8452_data *data = iio_priv(indio_dev);
> +
> +	return mma8452_change_config(data, MMA8452_TRANSIENT_THS, val & 0x7f);
> +}
> +
> +static int mma8452_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 mma8452_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	ret = i2c_smbus_read_byte_data(data->client, MMA8452_TRANSIENT_CFG);
> +	if (ret < 0)
> +		return ret;
> +
> +	return ret & MMA8452_TRANSIENT_CFG_CHAN_MASK(chan->scan_index) ? 1 : 0;
> +}
> +
> +static int mma8452_write_event_config(struct iio_dev *indio_dev,
> +	const struct iio_chan_spec *chan, enum iio_event_type type,
> +	enum iio_event_direction dir, int state)
> +{
> +	struct mma8452_data *data = iio_priv(indio_dev);
> +	int val;
> +
> +	val = i2c_smbus_read_byte_data(data->client, MMA8452_TRANSIENT_CFG);
> +	if (val < 0)
> +		return val;
> +
> +	if (state)
> +		val |= MMA8452_TRANSIENT_CFG_CHAN_MASK(chan->scan_index);
> +	else
> +		val &= ~MMA8452_TRANSIENT_CFG_CHAN_MASK(chan->scan_index);
> +
> +	val |= MMA8452_TRANSIENT_CFG_ELE;
> +
> +	return mma8452_change_config(data, MMA8452_TRANSIENT_CFG, val);
> +}
> +
> +static void mma8452_push_transient_event(struct iio_dev *indio_dev,
> +						int chan, u64 ts)
> +{
> +	iio_push_event(indio_dev,
> +		IIO_UNMOD_EVENT_CODE(IIO_ACCEL,
> +			chan,
> +			IIO_EV_TYPE_THRESH,
> +			IIO_EV_DIR_RISING),
> +		ts);
> +}
I'd prefer it if you dropped the wrapper.  Makes it more obvious what
is going on below.

Also it should be IIO_MOD_EVENT_CODE(IIO_ACCEL, 0, IIO_MOD_X, IIO_EV_TYPE_THRESH, IIO_EV_DIR_RISING).
> +
> +static void mma8452_transient_interrupt(struct iio_dev *indio_dev)
> +{
> +	struct mma8452_data *data = iio_priv(indio_dev);
> +	s64 ts = iio_get_time_ns();
> +	int src;
> +
> +	src = i2c_smbus_read_byte_data(data->client, MMA8452_TRANSIENT_SRC);
> +	if (src < 0)
> +		return;
> +
> +	if (src & MMA8452_TRANSIENT_SRC_XTRANSE)
> +		mma8452_push_transient_event(indio_dev, 0, ts);
> +
> +	if (src & MMA8452_TRANSIENT_SRC_YTRANSE)
> +		mma8452_push_transient_event(indio_dev, 1, ts);
> +
> +	if (src & MMA8452_TRANSIENT_SRC_ZTRANSE)
> +		mma8452_push_transient_event(indio_dev, 2, ts);
> +}
> +
> +static irqreturn_t mma8452_interrupt(int irq, void *p)
> +{
> +	struct iio_dev *indio_dev = p;
> +	struct mma8452_data *data = iio_priv(indio_dev);
> +	int src;
> +
> +	src = i2c_smbus_read_byte_data(data->client, MMA8452_INT_SRC);
> +	if (src < 0)
> +		return IRQ_NONE;
> +
> +	if (src & MMA8452_INT_TRANS) {
> +		mma8452_transient_interrupt(indio_dev);
> +		return IRQ_HANDLED;
> +	}
> +
> +	return IRQ_NONE;
> +}
> +
>  static irqreturn_t mma8452_trigger_handler(int irq, void *p)
>  {
>  	struct iio_poll_func *pf = p;
> @@ -316,6 +447,31 @@ static int mma8452_reg_access_dbg(struct iio_dev *indio_dev,
>  	return ret;
>  }
>
> +static const struct iio_event_spec mma8452_transient_event[] = {
> +	{
This is an interesting new event type - or at least it needs some
indication that it is high pass filtered...

It is closer to a rate of change detector than a threshold, but
not quite the same.

We could add an additional IIO_EV_INFO_HIGH_PASS_FILTER_3DB element
to the event to indicate the event is based on high pass filtered data.

Things will get interesting if there is a second low pass filtered
event of otherwise the same type. I guess we'll then just have to have
indexed events (we have hardware that would allow these, but it has never
made much sense to enable it).

> +		.type = IIO_EV_TYPE_THRESH,
> +		.dir = IIO_EV_DIR_RISING,
> +		.mask_separate = BIT(IIO_EV_INFO_ENABLE),
> +		.mask_shared_by_type = BIT(IIO_EV_INFO_VALUE),
> +	},
> +};
> +
> +/**
> + * Threshold is configured in fixed 8G/127 steps regardless of
> + * currently selected scale for measurement.
> + */
> +static IIO_CONST_ATTR_NAMED(accel_transient_scale, in_accel_scale, "0.617742");
> +
> +static struct attribute *mma8452_event_attributes[] = {
> +	&iio_const_attr_accel_transient_scale.dev_attr.attr,
This needs documenting under Documentation/ABI/testing/
> +	NULL,
> +};
> +
> +static struct attribute_group mma8452_event_attribute_group = {
> +	.attrs = mma8452_event_attributes,
> +	.name = "events",
> +};
> +
>  #define MMA8452_CHANNEL(axis, idx) { \
>  	.type = IIO_ACCEL, \
>  	.modified = 1, \
> @@ -332,6 +488,8 @@ static int mma8452_reg_access_dbg(struct iio_dev *indio_dev,
>  		.shift = 4, \
>  		.endianness = IIO_BE, \
>  	}, \
> +	.event_spec = mma8452_transient_event, \
> +	.num_event_specs = ARRAY_SIZE(mma8452_transient_event), \
>  }
>
>  static const struct iio_chan_spec mma8452_channels[] = {
> @@ -355,6 +513,11 @@ static const struct iio_info mma8452_info = {
>  	.attrs = &mma8452_group,
>  	.read_raw = &mma8452_read_raw,
>  	.write_raw = &mma8452_write_raw,
> +	.event_attrs = &mma8452_event_attribute_group,
> +	.read_event_value = &mma8452_read_thresh,
> +	.write_event_value = &mma8452_write_thresh,
> +	.read_event_config = &mma8452_read_event_config,
> +	.write_event_config = &mma8452_write_event_config,
>  	.debugfs_reg_access = &mma8452_reg_access_dbg,
>  	.driver_module = THIS_MODULE,
>  };
> @@ -425,6 +588,31 @@ static int mma8452_probe(struct i2c_client *client,
>  	if (ret < 0)
>  		return ret;
>
> +	/*
> +	 * By default set transient threshold to max to avoid events if
> +	 * enabling without configuring threshold
> +	 */
Why are we enabling it in the probe?  Would normally expect events to
only be enabled from userspace once the device is up and running...

> +	ret = i2c_smbus_write_byte_data(client, MMA8452_TRANSIENT_THS, 0x7f);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (client->irq) {
> +		int supported_interrupts = MMA8452_INT_TRANS;
> +
> +		/* Assume wired to INT1 pin */
> +		ret = i2c_smbus_write_byte_data(client,
> +						MMA8452_CTRL_REG5,
> +						supported_interrupts);
> +		if (ret < 0)
> +			return ret;
> +
> +		ret = i2c_smbus_write_byte_data(client,
> +						MMA8452_CTRL_REG4,
> +						supported_interrupts);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
>  	data->ctrl_reg1 = MMA8452_CTRL_ACTIVE |
>  		(MMA8452_CTRL_DR_DEFAULT << MMA8452_CTRL_DR_SHIFT);
>  	ret = i2c_smbus_write_byte_data(client, MMA8452_CTRL_REG1,
> @@ -440,8 +628,21 @@ static int mma8452_probe(struct i2c_client *client,
>  	ret = iio_device_register(indio_dev);
>  	if (ret < 0)
>  		goto buffer_cleanup;
We'd normally do this in the other order.  Hence have everything up
and running before we expose the userspace interfaces in iio_device_register.
> +
> +	if (client->irq) {
> +		ret = devm_request_threaded_irq(&client->dev,
> +						client->irq,
> +						NULL, mma8452_interrupt,
> +						IRQF_TRIGGER_LOW | IRQF_ONESHOT,
> +						client->name, indio_dev);
> +		if (ret)
> +			goto device_cleanup;
> +	}
>  	return 0;
>
> +device_cleanup:
> +	iio_device_unregister(indio_dev);
> +
>  buffer_cleanup:
>  	iio_triggered_buffer_cleanup(indio_dev);
>  	return ret;
>
> --
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