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

[Jonathan Cameron <jic23@kernel.org>]

On 14/11/15 18:45, Martin Kepplinger wrote:
> 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, ...).
Sure, but the set of modifiers allows for
in_accel_x&y_mag_falling_* etc and they aren't documented in this particular
form simply because no driver has used them yet ;)

> 
> 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,
>>>
>>
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-iio" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>