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Commit ed859fc1 authored by Martin Kepplinger's avatar Martin Kepplinger Committed by Jonathan Cameron
Browse files

iio: mma8452: add support for oversampling ratio 



This adds the following sysfs files according to the iio ABI:

-rw-r--r--    4096 in_accel_oversampling_ratio
-r--r--r--    4096 in_accel_oversampling_ratio_available

Internally, the device knows about 4 different power modes that differ
in oversampling ratio (and power consumption). We just show the user
what oversampling ratio(s) is/are available, depending on the current
frequency.

The referenced table in the datasheets makes it easier to understand.

Signed-off-by: default avatarMartin Kepplinger <martink@posteo.de>
Signed-off-by: default avatarChristoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent 6994aea7

drivers/iio/accel/mma8452.c

+160 −25
Original line number Diff line number Diff line
@@ -76,6 +76,8 @@ 
#define  MMA8452_CTRL_DR_DEFAULT		0x4 /* 50 Hz sample frequency */

#define MMA8452_CTRL_REG2			0x2b

#define  MMA8452_CTRL_REG2_RST			BIT(6)

#define  MMA8452_CTRL_REG2_MODS_SHIFT		3

#define  MMA8452_CTRL_REG2_MODS_MASK		0x1b

#define MMA8452_CTRL_REG4			0x2d

#define MMA8452_CTRL_REG5			0x2e

#define MMA8452_OFF_X				0x2f
@@ -257,20 +259,17 @@ static const int mma8452_samp_freq[8][2] = { 
	{6, 250000}, {1, 560000}

};



/* Datasheet table 35  (step time vs sample frequency) */

static const int mma8452_transient_time_step_us[8] = {

	1250,

	2500,

	5000,

	10000,

	20000,

	20000,

	20000,

	20000

/* Datasheet table: step time "Relationship with the ODR" (sample frequency) */

static const int mma8452_transient_time_step_us[4][8] = {

	{ 1250, 2500, 5000, 10000, 20000, 20000, 20000, 20000 },  /* normal */

	{ 1250, 2500, 5000, 10000, 20000, 80000, 80000, 80000 },  /* l p l n */

	{ 1250, 2500, 2500, 2500, 2500, 2500, 2500, 2500 },	  /* high res*/

	{ 1250, 2500, 5000, 10000, 20000, 80000, 160000, 160000 } /* l p */

};



/* Datasheet table 18 (normal mode) */

static const int mma8452_hp_filter_cutoff[8][4][2] = {

/* Datasheet table "High-Pass Filter Cutoff Options" */

static const int mma8452_hp_filter_cutoff[4][8][4][2] = {

	{ /* normal */

	{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },		/* 800 Hz sample */

	{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },		/* 400 Hz sample */

	{ {8, 0}, {4, 0}, {2, 0}, {1, 0} },		/* 200 Hz sample */
@@ -279,8 +278,61 @@ static const int mma8452_hp_filter_cutoff[8][4][2] = { 
	{ {2, 0}, {1, 0}, {0, 500000}, {0, 250000} },	/* 12.5 Hz sample */

	{ {2, 0}, {1, 0}, {0, 500000}, {0, 250000} },	/* 6.25 Hz sample */

	{ {2, 0}, {1, 0}, {0, 500000}, {0, 250000} }	/* 1.56 Hz sample */

	},

	{ /* low noise low power */

	{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },

	{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },

	{ {8, 0}, {4, 0}, {2, 0}, {1, 0} },

	{ {4, 0}, {2, 0}, {1, 0}, {0, 500000} },

	{ {2, 0}, {1, 0}, {0, 500000}, {0, 250000} },

	{ {0, 500000}, {0, 250000}, {0, 125000}, {0, 063000} },

	{ {0, 500000}, {0, 250000}, {0, 125000}, {0, 063000} },

	{ {0, 500000}, {0, 250000}, {0, 125000}, {0, 063000} }

	},

	{ /* high resolution */

	{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },

	{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },

	{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },

	{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },

	{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },

	{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },

	{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },

	{ {16, 0}, {8, 0}, {4, 0}, {2, 0} }

	},

	{ /* low power */

	{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },

	{ {8, 0}, {4, 0}, {2, 0}, {1, 0} },

	{ {4, 0}, {2, 0}, {1, 0}, {0, 500000} },

	{ {2, 0}, {1, 0}, {0, 500000}, {0, 250000} },

	{ {1, 0}, {0, 500000}, {0, 250000}, {0, 125000} },

	{ {0, 250000}, {0, 125000}, {0, 063000}, {0, 031000} },

	{ {0, 250000}, {0, 125000}, {0, 063000}, {0, 031000} },

	{ {0, 250000}, {0, 125000}, {0, 063000}, {0, 031000} }

	}

};



/* Datasheet table "MODS Oversampling modes averaging values at each ODR" */

static const u16 mma8452_os_ratio[4][8] = {

	/* 800 Hz, 400 Hz, ... , 1.56 Hz */

	{ 2, 4, 4, 4, 4, 16, 32, 128 },		/* normal */

	{ 2, 4, 4, 4, 4, 4, 8, 32 },		/* low power low noise */

	{ 2, 4, 8, 16, 32, 128, 256, 1024 },	/* high resolution */

	{ 2, 2, 2, 2, 2, 2, 4, 16 }		/* low power */

};



static int mma8452_get_power_mode(struct mma8452_data *data)

{

	int reg;



	reg = i2c_smbus_read_byte_data(data->client,

				       MMA8452_CTRL_REG2);

	if (reg < 0)

		return reg;



	return ((reg & MMA8452_CTRL_REG2_MODS_MASK) >>

		MMA8452_CTRL_REG2_MODS_SHIFT);

}



static ssize_t mma8452_show_samp_freq_avail(struct device *dev,

					    struct device_attribute *attr,

					    char *buf)
@@ -303,13 +355,42 @@ static ssize_t mma8452_show_scale_avail(struct device *dev, 
static ssize_t mma8452_show_hp_cutoff_avail(struct device *dev,

					    struct device_attribute *attr,

					    char *buf)

{

	struct iio_dev *indio_dev = dev_to_iio_dev(dev);

	struct mma8452_data *data = iio_priv(indio_dev);

	int i, j;



	i = mma8452_get_odr_index(data);

	j = mma8452_get_power_mode(data);

	if (j < 0)

		return j;



	return mma8452_show_int_plus_micros(buf, mma8452_hp_filter_cutoff[j][i],

		ARRAY_SIZE(mma8452_hp_filter_cutoff[0][0]));

}



static ssize_t mma8452_show_os_ratio_avail(struct device *dev,

					   struct device_attribute *attr,

					   char *buf)

{

	struct iio_dev *indio_dev = dev_to_iio_dev(dev);

	struct mma8452_data *data = iio_priv(indio_dev);

	int i = mma8452_get_odr_index(data);

	int j;

	u16 val = 0;

	size_t len = 0;



	for (j = 0; j < ARRAY_SIZE(mma8452_os_ratio); j++) {

		if (val == mma8452_os_ratio[j][i])

			continue;



		val = mma8452_os_ratio[j][i];



		len += scnprintf(buf + len, PAGE_SIZE - len, "%d ", val);

	}

	buf[len - 1] = '\n';



	return mma8452_show_int_plus_micros(buf, mma8452_hp_filter_cutoff[i],

		ARRAY_SIZE(mma8452_hp_filter_cutoff[0]));

	return len;

}



static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(mma8452_show_samp_freq_avail);
@@ -317,6 +398,8 @@ static IIO_DEVICE_ATTR(in_accel_scale_available, S_IRUGO, 
		       mma8452_show_scale_avail, NULL, 0);

static IIO_DEVICE_ATTR(in_accel_filter_high_pass_3db_frequency_available,

		       S_IRUGO, mma8452_show_hp_cutoff_avail, NULL, 0);

static IIO_DEVICE_ATTR(in_accel_oversampling_ratio_available, S_IRUGO,

		       mma8452_show_os_ratio_avail, NULL, 0);



static int mma8452_get_samp_freq_index(struct mma8452_data *data,

				       int val, int val2)
@@ -335,24 +418,33 @@ static int mma8452_get_scale_index(struct mma8452_data *data, int val, int val2) 
static int mma8452_get_hp_filter_index(struct mma8452_data *data,

				       int val, int val2)

{

	int i = mma8452_get_odr_index(data);

	int i, j;



	i = mma8452_get_odr_index(data);

	j = mma8452_get_power_mode(data);

	if (j < 0)

		return j;



	return mma8452_get_int_plus_micros_index(mma8452_hp_filter_cutoff[i],

		ARRAY_SIZE(mma8452_hp_filter_cutoff[0]), val, val2);

	return mma8452_get_int_plus_micros_index(mma8452_hp_filter_cutoff[j][i],

		ARRAY_SIZE(mma8452_hp_filter_cutoff[0][0]), val, val2);

}



static int mma8452_read_hp_filter(struct mma8452_data *data, int *hz, int *uHz)

{

	int i, ret;

	int j, i, ret;



	ret = i2c_smbus_read_byte_data(data->client, MMA8452_HP_FILTER_CUTOFF);

	if (ret < 0)

		return ret;



	i = mma8452_get_odr_index(data);

	j = mma8452_get_power_mode(data);

	if (j < 0)

		return j;



	ret &= MMA8452_HP_FILTER_CUTOFF_SEL_MASK;

	*hz = mma8452_hp_filter_cutoff[i][ret][0];

	*uHz = mma8452_hp_filter_cutoff[i][ret][1];

	*hz = mma8452_hp_filter_cutoff[j][i][ret][0];

	*uHz = mma8452_hp_filter_cutoff[j][i][ret][1];



	return 0;

}
@@ -414,6 +506,15 @@ static int mma8452_read_raw(struct iio_dev *indio_dev, 
		}



		return IIO_VAL_INT_PLUS_MICRO;

	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:

		ret = mma8452_get_power_mode(data);

		if (ret < 0)

			return ret;



		i = mma8452_get_odr_index(data);



		*val = mma8452_os_ratio[ret][i];

		return IIO_VAL_INT;

	}



	return -EINVAL;
@@ -480,6 +581,21 @@ static int mma8452_change_config(struct mma8452_data *data, u8 reg, u8 val) 
	return ret;

}



static int mma8452_set_power_mode(struct mma8452_data *data, u8 mode)

{

	int reg;



	reg = i2c_smbus_read_byte_data(data->client,

				       MMA8452_CTRL_REG2);

	if (reg < 0)

		return reg;



	reg &= ~MMA8452_CTRL_REG2_MODS_MASK;

	reg |= mode << MMA8452_CTRL_REG2_MODS_SHIFT;



	return mma8452_change_config(data, MMA8452_CTRL_REG2, reg);

}



/* returns >0 if in freefall mode, 0 if not or <0 if an error occurred */

static int mma8452_freefall_mode_enabled(struct mma8452_data *data)

{
@@ -597,6 +713,14 @@ static int mma8452_write_raw(struct iio_dev *indio_dev, 
		return mma8452_change_config(data, MMA8452_DATA_CFG,

					     data->data_cfg);



	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:

		ret = mma8452_get_odr_index(data);



		for (i = 0; i < ARRAY_SIZE(mma8452_os_ratio); i++) {

			if (mma8452_os_ratio[i][ret] == val)

				return mma8452_set_power_mode(data, i);

		}



	default:

		return -EINVAL;

	}
@@ -610,7 +734,7 @@ static int mma8452_read_thresh(struct iio_dev *indio_dev, 
			       int *val, int *val2)

{

	struct mma8452_data *data = iio_priv(indio_dev);

	int ret, us;

	int ret, us, power_mode;



	switch (info) {

	case IIO_EV_INFO_VALUE:
@@ -629,7 +753,11 @@ static int mma8452_read_thresh(struct iio_dev *indio_dev, 
		if (ret < 0)

			return ret;



		us = ret * mma8452_transient_time_step_us[

		power_mode = mma8452_get_power_mode(data);

		if (power_mode < 0)

			return power_mode;



		us = ret * mma8452_transient_time_step_us[power_mode][

				mma8452_get_odr_index(data)];

		*val = us / USEC_PER_SEC;

		*val2 = us % USEC_PER_SEC;
@@ -677,8 +805,12 @@ static int mma8452_write_thresh(struct iio_dev *indio_dev, 
					     val);



	case IIO_EV_INFO_PERIOD:

		ret = mma8452_get_power_mode(data);

		if (ret < 0)

			return ret;



		steps = (val * USEC_PER_SEC + val2) /

				mma8452_transient_time_step_us[

				mma8452_transient_time_step_us[ret][

					mma8452_get_odr_index(data)];



		if (steps < 0 || steps > 0xff)
@@ -978,7 +1110,8 @@ static struct attribute_group mma8452_event_attribute_group = { 
			      BIT(IIO_CHAN_INFO_CALIBBIAS), \

	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \

			BIT(IIO_CHAN_INFO_SCALE) | \

			BIT(IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY), \

			BIT(IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY) | \

			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \

	.scan_index = idx, \

	.scan_type = { \

		.sign = 's', \
@@ -998,7 +1131,8 @@ static struct attribute_group mma8452_event_attribute_group = { 
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \

		BIT(IIO_CHAN_INFO_CALIBBIAS), \

	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \

		BIT(IIO_CHAN_INFO_SCALE), \

		BIT(IIO_CHAN_INFO_SCALE) | \

		BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \

	.scan_index = idx, \

	.scan_type = { \

		.sign = 's', \
@@ -1171,6 +1305,7 @@ static struct attribute *mma8452_attributes[] = { 
	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,

	&iio_dev_attr_in_accel_scale_available.dev_attr.attr,

	&iio_dev_attr_in_accel_filter_high_pass_3db_frequency_available.dev_attr.attr,

	&iio_dev_attr_in_accel_oversampling_ratio_available.dev_attr.attr,

	NULL

};