Re: [PATCH 2/2] iio: mma8452: add freefall detection for Freescale's accelerometers

[Jonathan Cameron <jic23@kernel.org>]

On 08/12/15 16:21, Martin Kepplinger wrote:
> This adds freefall event detection to the supported devices. It adds
> the in_accel_x&y&z_mag_falling_en iio event attribute, which activates
> freefall mode.
> 
> In freefall mode, the current acceleration magnitude (AND combination
> of all axis values) is compared to the specified threshold.
> If it falls under the threshold (in_accel_mag_falling_value),
> the appropriate IIO event code is generated.
> 
> The values of rising and falling versions of various sysfs files are
> shared, which is compliant to the IIO specification.
> 
> This is what the sysfs "events" directory for these devices looks
> like after this change:
> 
> -rw-r--r--    4096 Oct 23 08:45 in_accel_mag_falling_period
> -rw-r--r--    4096 Oct 23 08:45 in_accel_mag_falling_value
> -rw-r--r--    4096 Oct 23 08:45 in_accel_mag_rising_period
> -rw-r--r--    4096 Oct 23 08:45 in_accel_mag_rising_value
> -r--r--r--    4096 Oct 23 08:45 in_accel_scale
> -rw-r--r--    4096 Oct 23 08:45 in_accel_x&y&z_mag_falling_en
> -rw-r--r--    4096 Oct 23 08:45 in_accel_x_mag_rising_en
> -rw-r--r--    4096 Oct 23 08:45 in_accel_y_mag_rising_en
> -rw-r--r--    4096 Oct 23 08:45 in_accel_z_mag_rising_en
> 
> Signed-off-by: Martin Kepplinger <martin.kepplinger@theobroma-systems.com>
> Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
I think the read back of other events being enabled is broken by this.
Otherwise a few other minor bits and bobs.

Jonathan
> ---
> Other combinations (x&y, x&z or y&z) might be added later. This is the most
> useful for freefall detection.
> 
> 
>  drivers/iio/accel/mma8452.c | 156 ++++++++++++++++++++++++++++++++++++++------
>  1 file changed, 137 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
> index 162bbef..c8ac88c 100644
> --- a/drivers/iio/accel/mma8452.c
> +++ b/drivers/iio/accel/mma8452.c
> @@ -15,7 +15,7 @@
>   *
>   * 7-bit I2C slave address 0x1c/0x1d (pin selectable)
>   *
> - * TODO: orientation / freefall events, autosleep
> + * TODO: orientation events, autosleep
>   */
>  
>  #include <linux/module.h>
> @@ -143,6 +143,14 @@ struct mma_chip_info {
>  	u8 ev_count;
>  };
>  
> +enum {
> +	idx_x,
> +	idx_y,
> +	idx_z,
> +	idx_ts,
> +	idx_xyz,
> +};
I would have slightly prefered the change to this enum to have been
done as a precursor patch as it would have lead to an easily checked
step 1 followed by the interesting stuff in step 2.
> +
>  static int mma8452_drdy(struct mma8452_data *data)
>  {
>  	int tries = 150;
> @@ -409,6 +417,46 @@ fail:
>  	return ret;
>  }
>  
> +static int mma8452_freefall_mode_enabled(struct mma8452_data *data)
> +{
> +	int val;
> +	const struct mma_chip_info *chip = data->chip_info;
> +
> +	val = i2c_smbus_read_byte_data(data->client, chip->ev_cfg);
> +	if (val < 0)
> +		return val;
> +
> +	return !(val & MMA8452_FF_MT_CFG_OAE);
> +}
> +
> +static int mma8452_set_freefall_mode(struct mma8452_data *data, u8 state)
> +{
> +	int val, ret;
> +	const struct mma_chip_info *chip = data->chip_info;
> +
> +	val = i2c_smbus_read_byte_data(data->client, chip->ev_cfg);
> +	if (val < 0)
> +		return val;
> +
> +	if (state && !(mma8452_freefall_mode_enabled(data))) {
> +		val |= BIT(idx_x + chip->ev_cfg_chan_shift);
> +		val |= BIT(idx_y + chip->ev_cfg_chan_shift);
> +		val |= BIT(idx_z + chip->ev_cfg_chan_shift);
> +		val &= ~MMA8452_FF_MT_CFG_OAE;
> +	} else if (!state && mma8452_freefall_mode_enabled(data)) {
> +		val &= ~BIT(idx_x + chip->ev_cfg_chan_shift);
> +		val &= ~BIT(idx_y + chip->ev_cfg_chan_shift);
> +		val &= ~BIT(idx_z + chip->ev_cfg_chan_shift);
> +		val |= MMA8452_FF_MT_CFG_OAE;
> +	}
> +
> +	ret = mma8452_change_config(data, chip->ev_cfg, val);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
>  static int mma8452_set_hp_filter_frequency(struct mma8452_data *data,
>  					   int val, int val2)
>  {
> @@ -602,6 +650,11 @@ static int mma8452_read_event_config(struct iio_dev *indio_dev,
>  	const struct mma_chip_info *chip = data->chip_info;
>  	int ret;
>  
> +	switch (chan->channel2) {
> +	case IIO_MOD_X_AND_Y_AND_Z:
> +		return mma8452_freefall_mode_enabled(data);
> +	}
> +
>  	ret = i2c_smbus_read_byte_data(data->client,
>  				       data->chip_info->ev_cfg);
>  	if (ret < 0)
I may have missed something here, but I think the check for the other events
being enabled needs updating as well.  We are using the same bits in the
register afterall.

> @@ -620,6 +673,11 @@ static int mma8452_write_event_config(struct iio_dev *indio_dev,
>  	const struct mma_chip_info *chip = data->chip_info;
>  	int val;
>  
> +	switch (chan->channel2) {
> +	case IIO_MOD_X_AND_Y_AND_Z:
> +		return mma8452_set_freefall_mode(data, state);
> +	}
> +
>  	val = i2c_smbus_read_byte_data(data->client, chip->ev_cfg);
>  	if (val < 0)
>  		return val;
> @@ -630,7 +688,6 @@ static int mma8452_write_event_config(struct iio_dev *indio_dev,
>  		val &= ~BIT(chan->scan_index + chip->ev_cfg_chan_shift);
>  
>  	val |= chip->ev_cfg_ele;
> -	val |= MMA8452_FF_MT_CFG_OAE;
>  
>  	return mma8452_change_config(data, chip->ev_cfg, val);
>  }
> @@ -639,12 +696,26 @@ 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;
> +	int src, cfg;
>  
>  	src = i2c_smbus_read_byte_data(data->client, data->chip_info->ev_src);
>  	if (src < 0)
>  		return;
>  
> +	cfg = i2c_smbus_read_byte_data(data->client, data->chip_info->ev_cfg);
> +	if (cfg < 0)
> +		return;
This strikes me as odd.  I'd assume ev_cfg could be cached and avoid the
read here?  It's basically saying if we enable a free fall event all
the individual ones are disabled... 
> +
> +	if (!(cfg & MMA8452_FF_MT_CFG_OAE)) {
> +		iio_push_event(indio_dev,
> +			       IIO_MOD_EVENT_CODE(IIO_ACCEL, 0,
> +						  IIO_MOD_X_AND_Y_AND_Z,
> +						  IIO_EV_TYPE_MAG,
> +						  IIO_EV_DIR_FALLING),
> +			       ts);
> +		return;
> +	}
> +
>  	if (src & data->chip_info->ev_src_xe)
>  		iio_push_event(indio_dev,
>  			       IIO_MOD_EVENT_CODE(IIO_ACCEL, 0, IIO_MOD_X,
> @@ -738,6 +809,27 @@ static int mma8452_reg_access_dbg(struct iio_dev *indio_dev,
>  	return 0;
>  }
>  
> +static const struct iio_event_spec mma8452_freefall_event[] = {
> +	{
> +		.type = IIO_EV_TYPE_MAG,
> +		.dir = IIO_EV_DIR_FALLING,
> +		.mask_separate = BIT(IIO_EV_INFO_ENABLE),
> +		.mask_shared_by_type = BIT(IIO_EV_INFO_VALUE) |
> +					BIT(IIO_EV_INFO_PERIOD) |
> +					BIT(IIO_EV_INFO_HIGH_PASS_FILTER_3DB)
> +	},
> +};
> +
> +static const struct iio_event_spec mma8652_freefall_event[] = {
> +	{
> +		.type = IIO_EV_TYPE_MAG,
> +		.dir = IIO_EV_DIR_FALLING,
> +		.mask_separate = BIT(IIO_EV_INFO_ENABLE),
> +		.mask_shared_by_type = BIT(IIO_EV_INFO_VALUE) |
> +					BIT(IIO_EV_INFO_PERIOD)
> +	},
> +};
> +
>  static const struct iio_event_spec mma8452_transient_event[] = {
>  	{
>  		.type = IIO_EV_TYPE_MAG,
> @@ -774,6 +866,24 @@ static struct attribute_group mma8452_event_attribute_group = {
>  	.attrs = mma8452_event_attributes,
>  };
>  
> +#define MMA8452_FREEFALL_CHANNEL(modifier, idx) { \
> +	.type = IIO_ACCEL, \
> +	.modified = 1, \
> +	.channel2 = modifier, \
> +	.scan_index = idx, \
> +	.event_spec = mma8452_freefall_event, \
> +	.num_event_specs = ARRAY_SIZE(mma8452_freefall_event), \
> +}
> +
> +#define MMA8652_FREEFALL_CHANNEL(modifier, idx) { \
> +	.type = IIO_ACCEL, \
> +	.modified = 1, \
> +	.channel2 = modifier, \
> +	.scan_index = idx, \
This isn't a 'real' channel with data to push into the buffer,
so I'd expect to see an scan_index of -1 to stop it appearing
under there. Same for the other varients.

> +	.event_spec = mma8652_freefall_event, \
> +	.num_event_specs = ARRAY_SIZE(mma8652_freefall_event), \
> +}
> +
>  #define MMA8452_CHANNEL(axis, idx, bits) { \
>  	.type = IIO_ACCEL, \
>  	.modified = 1, \
> @@ -816,31 +926,35 @@ static struct attribute_group mma8452_event_attribute_group = {
>  }
>  
>  static const struct iio_chan_spec mma8452_channels[] = {
> -	MMA8452_CHANNEL(X, 0, 12),
> -	MMA8452_CHANNEL(Y, 1, 12),
> -	MMA8452_CHANNEL(Z, 2, 12),
> -	IIO_CHAN_SOFT_TIMESTAMP(3),
> +	MMA8452_CHANNEL(X, idx_x, 12),
> +	MMA8452_CHANNEL(Y, idx_y, 12),
> +	MMA8452_CHANNEL(Z, idx_z, 12),
> +	IIO_CHAN_SOFT_TIMESTAMP(idx_ts),
> +	MMA8452_FREEFALL_CHANNEL(IIO_MOD_X_AND_Y_AND_Z, idx_xyz),
>  };
>  
>  static const struct iio_chan_spec mma8453_channels[] = {
> -	MMA8452_CHANNEL(X, 0, 10),
> -	MMA8452_CHANNEL(Y, 1, 10),
> -	MMA8452_CHANNEL(Z, 2, 10),
> -	IIO_CHAN_SOFT_TIMESTAMP(3),
> +	MMA8452_CHANNEL(X, idx_x, 10),
> +	MMA8452_CHANNEL(Y, idx_y, 10),
> +	MMA8452_CHANNEL(Z, idx_z, 10),
> +	IIO_CHAN_SOFT_TIMESTAMP(idx_ts),
> +	MMA8452_FREEFALL_CHANNEL(IIO_MOD_X_AND_Y_AND_Z, idx_xyz),
>  };
>  
>  static const struct iio_chan_spec mma8652_channels[] = {
> -	MMA8652_CHANNEL(X, 0, 12),
> -	MMA8652_CHANNEL(Y, 1, 12),
> -	MMA8652_CHANNEL(Z, 2, 12),
> -	IIO_CHAN_SOFT_TIMESTAMP(3),
> +	MMA8652_CHANNEL(X, idx_x, 12),
> +	MMA8652_CHANNEL(Y, idx_y, 12),
> +	MMA8652_CHANNEL(Z, idx_z, 12),
> +	IIO_CHAN_SOFT_TIMESTAMP(idx_ts),
> +	MMA8652_FREEFALL_CHANNEL(IIO_MOD_X_AND_Y_AND_Z, idx_xyz),
>  };
>  
>  static const struct iio_chan_spec mma8653_channels[] = {
> -	MMA8652_CHANNEL(X, 0, 10),
> -	MMA8652_CHANNEL(Y, 1, 10),
> -	MMA8652_CHANNEL(Z, 2, 10),
> -	IIO_CHAN_SOFT_TIMESTAMP(3),
> +	MMA8652_CHANNEL(X, idx_x, 10),
> +	MMA8652_CHANNEL(Y, idx_y, 10),
> +	MMA8652_CHANNEL(Z, idx_z, 10),
> +	IIO_CHAN_SOFT_TIMESTAMP(idx_ts),
> +	MMA8652_FREEFALL_CHANNEL(IIO_MOD_X_AND_Y_AND_Z, idx_xyz),
>  };
>  
>  enum {
> @@ -1183,6 +1297,10 @@ static int mma8452_probe(struct i2c_client *client,
>  	if (ret < 0)
>  		goto buffer_cleanup;
>  
> +	ret = mma8452_set_freefall_mode(data, 0);
> +	if (ret)
> +		return ret;
> +
>  	return 0;
>  
>  buffer_cleanup:
>