Re: [PATCH 1/3] iio: mma8452: add freefall detection for Freescale's accelerometers

[Martin Kepplinger <martink@posteo.de>]

Am 2015-11-14 um 19:03 schrieb Jonathan Cameron:
> On 11/11/15 18:38, 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 values of all activated axis
>> are added and if the *sum* falls *under* the threshold specified
>> (in_accel_mag_falling_value), the appropriate IIO event code
>> is generated.
>>
>> By enabling freefall mode (in_accel_x&y&z_mag_falling_en)
>> all 3 axis are enabled too as this describes a classic freefall
>> detection. Of course the user is free to disable one or more directions.
>>
>> 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_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_falling_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_falling_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>
> Looks pretty good to me (other than obviously the bits Lars already
> picked up on!)
> 
> My only real comment was that you could do the rest of the combined
> possibilities whilst you are here (if you want to!)  You've
> picked the mostly obviously useful one though so maybe leave it
> at that.

I'm not sure what you mean. There is only in_accel_x&y&z_mag_falling_en
documented. So my guess was to have this to enable freefall mode, taking
into account the currently enabled falling axis
(in_accel_x_mag_falling_en, ...).

Plus enabling all of them. The user has to check it anyways, but maybe I
should leave that out (which is a slightly different matter from what
you meant).

> 
> Jonathan
>> ---
>>  drivers/iio/accel/mma8452.c | 114 ++++++++++++++++++++++++++++++++++++++++++--
>>  1 file changed, 111 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
>> index 116a6e4..dedcc1d 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>
>> @@ -144,6 +144,12 @@ struct mma_chip_info {
>>  	u8 ev_count;
>>  };
>>  
>> +enum {
>> +	axis_x,
>> +	axis_y,
>> +	axis_z,
>> +};
>> +
>>  static int mma8452_drdy(struct mma8452_data *data)
>>  {
>>  	int tries = 150;
>> @@ -410,6 +416,74 @@ fail:
>>  	return ret;
>>  }
>>  
>> +static ssize_t mma8452_get_freefall_mode(struct device *dev,
>> +					 struct device_attribute *attr,
>> +					 char *buf)
>> +{
>> +	int val;
>> +	struct mma8452_data *data = iio_priv(i2c_get_clientdata(
>> +					     to_i2c_client(dev)));
>> +	const struct mma_chip_info *chip = data->chip_info;
>> +
>> +	mutex_lock(&data->lock);
>> +	val = i2c_smbus_read_byte_data(data->client, chip->ev_cfg);
>> +	mutex_unlock(&data->lock);
>> +	if (val < 0)
>> +		return val;
>> +
>> +	return scnprintf(buf, PAGE_SIZE, "%d\n",
>> +			 !(val & MMA8452_FF_MT_CFG_OAE));
>> +}
>> +
>> +static ssize_t mma8452_set_freefall_mode(struct device *dev,
>> +					 struct device_attribute *attr,
>> +					 const char *buf,
>> +					 size_t len)
>> +{
>> +	int val, ret;
>> +	u8 user_val;
>> +	struct mma8452_data *data = iio_priv(i2c_get_clientdata(
>> +					     to_i2c_client(dev)));
>> +	const struct mma_chip_info *chip = data->chip_info;
>> +
>> +	ret = kstrtou8(buf, 10, &user_val);
>> +	if (ret)
>> +		goto err;
>> +
>> +	val = i2c_smbus_read_byte_data(data->client, chip->ev_cfg);
>> +	if (val < 0) {
>> +		ret = val;
>> +		goto err;
>> +	}
>> +
>> +	if (user_val && (val & MMA8452_FF_MT_CFG_OAE)) {
>> +		val |= BIT(axis_x + chip->ev_cfg_chan_shift);
>> +		val |= BIT(axis_y + chip->ev_cfg_chan_shift);
>> +		val |= BIT(axis_z + chip->ev_cfg_chan_shift);
>> +		val &= ~MMA8452_FF_MT_CFG_OAE;
>> +	} else if (!user_val && !(val & MMA8452_FF_MT_CFG_OAE)) {
>> +		val &= ~BIT(axis_x + chip->ev_cfg_chan_shift);
>> +		val &= ~BIT(axis_y + chip->ev_cfg_chan_shift);
>> +		val &= ~BIT(axis_z + chip->ev_cfg_chan_shift);
>> +		val |= MMA8452_FF_MT_CFG_OAE;
>> +	}
> It would be a pain to do perhaps and of limited interest, but
> you could support all the combinations as well as separate
> events... (clearly enabling one disables another, but that's fine
> under the ABI)
> 
> (There's a reason we have x&y, x&z, etc :)  Maybe it's one
> to leave for an intersted party to pick up in future if they
> care.
> 
>> +
>> +	ret = mma8452_change_config(data, chip->ev_cfg, val);
>> +	if (ret)
>> +		goto err;
>> +
>> +	return len;
>> +err:
>> +	return ret;
>> +}
>> +
>> +static IIO_DEVICE_ATTR_NAMED(accel_xayaz_mag_falling_en,
>> +			     in_accel_x&y&z_mag_falling_en,
>> +			     S_IRUGO | S_IWUSR,
>> +			     mma8452_get_freefall_mode,
>> +			     mma8452_set_freefall_mode,
>> +			     0);
>> +
> Lars is correct on this one. If it's not getting created something is
> going wrong in an odd fashion!
> 
>>  static int mma8452_set_hp_filter_frequency(struct mma8452_data *data,
>>  					   int val, int val2)
>>  {
>> @@ -631,7 +705,6 @@ 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);
>>  }
>> @@ -640,12 +713,26 @@ 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;
>> +
>> +	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,
>> @@ -758,6 +845,13 @@ static const struct iio_event_spec mma8452_motion_event[] = {
>>  		.mask_shared_by_type = BIT(IIO_EV_INFO_VALUE) |
>>  					BIT(IIO_EV_INFO_PERIOD)
>>  	},
>> +	{
>> +		.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)
>> +	},
>>  };
>>  
>>  /*
>> @@ -768,6 +862,7 @@ 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,
>> +	&iio_dev_attr_accel_xayaz_mag_falling_en.dev_attr.attr,
>>  	NULL,
>>  };
>>  
>> @@ -1057,6 +1152,7 @@ static int mma8452_probe(struct i2c_client *client,
>>  	struct mma8452_data *data;
>>  	struct iio_dev *indio_dev;
>>  	int ret;
>> +	u8 val;
>>  	const struct of_device_id *match;
>>  
>>  	match = of_match_device(mma8452_dt_ids, &client->dev);
>> @@ -1158,6 +1254,18 @@ static int mma8452_probe(struct i2c_client *client,
>>  			return ret;
>>  	}
>>  
>> +	/* don't activate freefall mode on startup */
>> +	ret = i2c_smbus_read_byte_data(data->client, data->chip_info->ev_cfg);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	val = ret;
>> +	ret = i2c_smbus_write_byte_data(client,
>> +					data->chip_info->ev_cfg,
>> +					val | MMA8452_FF_MT_CFG_OAE);
>> +	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,
>>
>