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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: Martin Kepplinger <martink@posteo.de>
Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Martin Kepplinger 2016-04-25 14:08:25 +02:00 committed by Jonathan Cameron
parent 6994aea784
commit ed859fc17d
1 changed files with 161 additions and 26 deletions
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187
drivers/iio/accel/mma8452.c
View File

@ -76,6 +76,8 @@
#define MMA8452_CTRL_DR_DEFAULT 0x4 /* 50 Hz sample frequency */ #define MMA8452_CTRL_DR_DEFAULT 0x4 /* 50 Hz sample frequency */
#define MMA8452_CTRL_REG2 0x2b #define MMA8452_CTRL_REG2 0x2b
#define MMA8452_CTRL_REG2_RST BIT(6) #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_REG4 0x2d
#define MMA8452_CTRL_REG5 0x2e #define MMA8452_CTRL_REG5 0x2e
#define MMA8452_OFF_X 0x2f #define MMA8452_OFF_X 0x2f
@ -257,20 +259,17 @@ static const int mma8452_samp_freq[8][2] = {
{6, 250000}, {1, 560000} {6, 250000}, {1, 560000}
}; };
/* Datasheet table 35 (step time vs sample frequency) */ /* Datasheet table: step time "Relationship with the ODR" (sample frequency) */
static const int mma8452_transient_time_step_us[8] = { static const int mma8452_transient_time_step_us[4][8] = {
1250, { 1250, 2500, 5000, 10000, 20000, 20000, 20000, 20000 }, /* normal */
2500, { 1250, 2500, 5000, 10000, 20000, 80000, 80000, 80000 }, /* l p l n */
5000, { 1250, 2500, 2500, 2500, 2500, 2500, 2500, 2500 }, /* high res*/
10000, { 1250, 2500, 5000, 10000, 20000, 80000, 160000, 160000 } /* l p */
20000,
20000,
20000,
20000
}; };
/* Datasheet table 18 (normal mode) */ /* Datasheet table "High-Pass Filter Cutoff Options" */
static const int mma8452_hp_filter_cutoff[8][4][2] = { 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} }, /* 800 Hz sample */
{ {16, 0}, {8, 0}, {4, 0}, {2, 0} }, /* 400 Hz sample */ { {16, 0}, {8, 0}, {4, 0}, {2, 0} }, /* 400 Hz sample */
{ {8, 0}, {4, 0}, {2, 0}, {1, 0} }, /* 200 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} }, /* 12.5 Hz sample */
{ {2, 0}, {1, 0}, {0, 500000}, {0, 250000} }, /* 6.25 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 */ { {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, static ssize_t mma8452_show_samp_freq_avail(struct device *dev,
struct device_attribute *attr, struct device_attribute *attr,
char *buf) char *buf)
@ -306,10 +358,39 @@ static ssize_t mma8452_show_hp_cutoff_avail(struct device *dev,
{ {
struct iio_dev *indio_dev = dev_to_iio_dev(dev); struct iio_dev *indio_dev = dev_to_iio_dev(dev);
struct mma8452_data *data = iio_priv(indio_dev); struct mma8452_data *data = iio_priv(indio_dev);
int i = mma8452_get_odr_index(data); int i, j;
return mma8452_show_int_plus_micros(buf, mma8452_hp_filter_cutoff[i], i = mma8452_get_odr_index(data);
ARRAY_SIZE(mma8452_hp_filter_cutoff[0])); 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 len;
} }
static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(mma8452_show_samp_freq_avail); 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); mma8452_show_scale_avail, NULL, 0);
static IIO_DEVICE_ATTR(in_accel_filter_high_pass_3db_frequency_available, static IIO_DEVICE_ATTR(in_accel_filter_high_pass_3db_frequency_available,
S_IRUGO, mma8452_show_hp_cutoff_avail, NULL, 0); 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, static int mma8452_get_samp_freq_index(struct mma8452_data *data,
int val, int val2) 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, static int mma8452_get_hp_filter_index(struct mma8452_data *data,
int val, int val2) int val, int val2)
{ {
int i = mma8452_get_odr_index(data); int i, j;
return mma8452_get_int_plus_micros_index(mma8452_hp_filter_cutoff[i], i = mma8452_get_odr_index(data);
ARRAY_SIZE(mma8452_hp_filter_cutoff[0]), val, val2); j = mma8452_get_power_mode(data);
if (j < 0)
return j;
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) 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); ret = i2c_smbus_read_byte_data(data->client, MMA8452_HP_FILTER_CUTOFF);
if (ret < 0) if (ret < 0)
return ret; return ret;
i = mma8452_get_odr_index(data); i = mma8452_get_odr_index(data);
j = mma8452_get_power_mode(data);
if (j < 0)
return j;
ret &= MMA8452_HP_FILTER_CUTOFF_SEL_MASK; ret &= MMA8452_HP_FILTER_CUTOFF_SEL_MASK;
*hz = mma8452_hp_filter_cutoff[i][ret][0]; *hz = mma8452_hp_filter_cutoff[j][i][ret][0];
*uHz = mma8452_hp_filter_cutoff[i][ret][1]; *uHz = mma8452_hp_filter_cutoff[j][i][ret][1];
return 0; return 0;
} }
@ -414,6 +506,15 @@ static int mma8452_read_raw(struct iio_dev *indio_dev,
} }
return IIO_VAL_INT_PLUS_MICRO; 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; return -EINVAL;
@ -480,6 +581,21 @@ fail:
return ret; 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 */ /* 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) 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, return mma8452_change_config(data, MMA8452_DATA_CFG,
data->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: default:
return -EINVAL; return -EINVAL;
} }
@ -610,7 +734,7 @@ static int mma8452_read_thresh(struct iio_dev *indio_dev,
int *val, int *val2) int *val, int *val2)
{ {
struct mma8452_data *data = iio_priv(indio_dev); struct mma8452_data *data = iio_priv(indio_dev);
int ret, us; int ret, us, power_mode;
switch (info) { switch (info) {
case IIO_EV_INFO_VALUE: case IIO_EV_INFO_VALUE:
@ -629,7 +753,11 @@ static int mma8452_read_thresh(struct iio_dev *indio_dev,
if (ret < 0) if (ret < 0)
return ret; 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)]; mma8452_get_odr_index(data)];
*val = us / USEC_PER_SEC; *val = us / USEC_PER_SEC;
*val2 = us % USEC_PER_SEC; *val2 = us % USEC_PER_SEC;
@ -677,8 +805,12 @@ static int mma8452_write_thresh(struct iio_dev *indio_dev,
val); val);
case IIO_EV_INFO_PERIOD: case IIO_EV_INFO_PERIOD:
ret = mma8452_get_power_mode(data);
if (ret < 0)
return ret;
steps = (val * USEC_PER_SEC + val2) / steps = (val * USEC_PER_SEC + val2) /
mma8452_transient_time_step_us[ mma8452_transient_time_step_us[ret][
mma8452_get_odr_index(data)]; mma8452_get_odr_index(data)];
if (steps < 0 || steps > 0xff) if (steps < 0 || steps > 0xff)
@ -978,7 +1110,8 @@ static struct attribute_group mma8452_event_attribute_group = {
BIT(IIO_CHAN_INFO_CALIBBIAS), \ BIT(IIO_CHAN_INFO_CALIBBIAS), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \ .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_HIGH_PASS_FILTER_3DB_FREQUENCY), \ BIT(IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY) | \
BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
.scan_index = idx, \ .scan_index = idx, \
.scan_type = { \ .scan_type = { \
.sign = 's', \ .sign = 's', \
@ -998,7 +1131,8 @@ static struct attribute_group mma8452_event_attribute_group = {
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
BIT(IIO_CHAN_INFO_CALIBBIAS), \ BIT(IIO_CHAN_INFO_CALIBBIAS), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \ .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_index = idx, \
.scan_type = { \ .scan_type = { \
.sign = 's', \ .sign = 's', \
@ -1171,6 +1305,7 @@ static struct attribute *mma8452_attributes[] = {
&iio_dev_attr_sampling_frequency_available.dev_attr.attr, &iio_dev_attr_sampling_frequency_available.dev_attr.attr,
&iio_dev_attr_in_accel_scale_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_filter_high_pass_3db_frequency_available.dev_attr.attr,
&iio_dev_attr_in_accel_oversampling_ratio_available.dev_attr.attr,
NULL NULL
}; };