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
Jonathan Cameron
parent
6994aea784
commit
ed859fc17d
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@ -76,6 +76,8 @@
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#define MMA8452_CTRL_DR_DEFAULT 0x4 /* 50 Hz sample frequency */
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#define MMA8452_CTRL_REG2 0x2b
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#define MMA8452_CTRL_REG2_RST BIT(6)
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#define MMA8452_CTRL_REG2_MODS_SHIFT 3
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#define MMA8452_CTRL_REG2_MODS_MASK 0x1b
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#define MMA8452_CTRL_REG4 0x2d
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#define MMA8452_CTRL_REG5 0x2e
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#define MMA8452_OFF_X 0x2f
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@ -257,20 +259,17 @@ static const int mma8452_samp_freq[8][2] = {
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{6, 250000}, {1, 560000}
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};
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/* Datasheet table 35 (step time vs sample frequency) */
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static const int mma8452_transient_time_step_us[8] = {
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1250,
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2500,
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5000,
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10000,
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20000,
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20000,
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20000,
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20000
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/* Datasheet table: step time "Relationship with the ODR" (sample frequency) */
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static const int mma8452_transient_time_step_us[4][8] = {
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{ 1250, 2500, 5000, 10000, 20000, 20000, 20000, 20000 }, /* normal */
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{ 1250, 2500, 5000, 10000, 20000, 80000, 80000, 80000 }, /* l p l n */
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{ 1250, 2500, 2500, 2500, 2500, 2500, 2500, 2500 }, /* high res*/
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{ 1250, 2500, 5000, 10000, 20000, 80000, 160000, 160000 } /* l p */
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};
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/* Datasheet table 18 (normal mode) */
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static const int mma8452_hp_filter_cutoff[8][4][2] = {
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/* Datasheet table "High-Pass Filter Cutoff Options" */
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static const int mma8452_hp_filter_cutoff[4][8][4][2] = {
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{ /* normal */
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{ {16, 0}, {8, 0}, {4, 0}, {2, 0} }, /* 800 Hz sample */
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{ {16, 0}, {8, 0}, {4, 0}, {2, 0} }, /* 400 Hz sample */
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{ {8, 0}, {4, 0}, {2, 0}, {1, 0} }, /* 200 Hz sample */
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@ -279,8 +278,61 @@ static const int mma8452_hp_filter_cutoff[8][4][2] = {
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{ {2, 0}, {1, 0}, {0, 500000}, {0, 250000} }, /* 12.5 Hz sample */
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{ {2, 0}, {1, 0}, {0, 500000}, {0, 250000} }, /* 6.25 Hz sample */
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{ {2, 0}, {1, 0}, {0, 500000}, {0, 250000} } /* 1.56 Hz sample */
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},
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{ /* low noise low power */
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{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },
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{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },
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{ {8, 0}, {4, 0}, {2, 0}, {1, 0} },
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{ {4, 0}, {2, 0}, {1, 0}, {0, 500000} },
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{ {2, 0}, {1, 0}, {0, 500000}, {0, 250000} },
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{ {0, 500000}, {0, 250000}, {0, 125000}, {0, 063000} },
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{ {0, 500000}, {0, 250000}, {0, 125000}, {0, 063000} },
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{ {0, 500000}, {0, 250000}, {0, 125000}, {0, 063000} }
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},
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{ /* high resolution */
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{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },
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{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },
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{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },
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{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },
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{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },
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{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },
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{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },
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{ {16, 0}, {8, 0}, {4, 0}, {2, 0} }
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},
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{ /* low power */
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{ {16, 0}, {8, 0}, {4, 0}, {2, 0} },
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{ {8, 0}, {4, 0}, {2, 0}, {1, 0} },
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{ {4, 0}, {2, 0}, {1, 0}, {0, 500000} },
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{ {2, 0}, {1, 0}, {0, 500000}, {0, 250000} },
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{ {1, 0}, {0, 500000}, {0, 250000}, {0, 125000} },
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{ {0, 250000}, {0, 125000}, {0, 063000}, {0, 031000} },
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{ {0, 250000}, {0, 125000}, {0, 063000}, {0, 031000} },
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{ {0, 250000}, {0, 125000}, {0, 063000}, {0, 031000} }
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}
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};
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/* Datasheet table "MODS Oversampling modes averaging values at each ODR" */
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static const u16 mma8452_os_ratio[4][8] = {
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/* 800 Hz, 400 Hz, ... , 1.56 Hz */
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{ 2, 4, 4, 4, 4, 16, 32, 128 }, /* normal */
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{ 2, 4, 4, 4, 4, 4, 8, 32 }, /* low power low noise */
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{ 2, 4, 8, 16, 32, 128, 256, 1024 }, /* high resolution */
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{ 2, 2, 2, 2, 2, 2, 4, 16 } /* low power */
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};
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static int mma8452_get_power_mode(struct mma8452_data *data)
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{
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int reg;
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reg = i2c_smbus_read_byte_data(data->client,
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MMA8452_CTRL_REG2);
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if (reg < 0)
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return reg;
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return ((reg & MMA8452_CTRL_REG2_MODS_MASK) >>
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MMA8452_CTRL_REG2_MODS_SHIFT);
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}
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static ssize_t mma8452_show_samp_freq_avail(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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@ -306,10 +358,39 @@ static ssize_t mma8452_show_hp_cutoff_avail(struct device *dev,
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{
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struct iio_dev *indio_dev = dev_to_iio_dev(dev);
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struct mma8452_data *data = iio_priv(indio_dev);
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int i = mma8452_get_odr_index(data);
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int i, j;
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return mma8452_show_int_plus_micros(buf, mma8452_hp_filter_cutoff[i],
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ARRAY_SIZE(mma8452_hp_filter_cutoff[0]));
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i = mma8452_get_odr_index(data);
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j = mma8452_get_power_mode(data);
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if (j < 0)
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return j;
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return mma8452_show_int_plus_micros(buf, mma8452_hp_filter_cutoff[j][i],
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ARRAY_SIZE(mma8452_hp_filter_cutoff[0][0]));
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}
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static ssize_t mma8452_show_os_ratio_avail(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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struct iio_dev *indio_dev = dev_to_iio_dev(dev);
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struct mma8452_data *data = iio_priv(indio_dev);
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int i = mma8452_get_odr_index(data);
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int j;
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u16 val = 0;
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size_t len = 0;
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for (j = 0; j < ARRAY_SIZE(mma8452_os_ratio); j++) {
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if (val == mma8452_os_ratio[j][i])
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continue;
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val = mma8452_os_ratio[j][i];
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len += scnprintf(buf + len, PAGE_SIZE - len, "%d ", val);
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}
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buf[len - 1] = '\n';
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return len;
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}
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static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(mma8452_show_samp_freq_avail);
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@ -317,6 +398,8 @@ static IIO_DEVICE_ATTR(in_accel_scale_available, S_IRUGO,
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mma8452_show_scale_avail, NULL, 0);
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static IIO_DEVICE_ATTR(in_accel_filter_high_pass_3db_frequency_available,
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S_IRUGO, mma8452_show_hp_cutoff_avail, NULL, 0);
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static IIO_DEVICE_ATTR(in_accel_oversampling_ratio_available, S_IRUGO,
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mma8452_show_os_ratio_avail, NULL, 0);
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static int mma8452_get_samp_freq_index(struct mma8452_data *data,
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int val, int val2)
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@ -335,24 +418,33 @@ static int mma8452_get_scale_index(struct mma8452_data *data, int val, int val2)
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static int mma8452_get_hp_filter_index(struct mma8452_data *data,
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int val, int val2)
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{
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int i = mma8452_get_odr_index(data);
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int i, j;
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return mma8452_get_int_plus_micros_index(mma8452_hp_filter_cutoff[i],
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ARRAY_SIZE(mma8452_hp_filter_cutoff[0]), val, val2);
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i = mma8452_get_odr_index(data);
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j = mma8452_get_power_mode(data);
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if (j < 0)
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return j;
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return mma8452_get_int_plus_micros_index(mma8452_hp_filter_cutoff[j][i],
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ARRAY_SIZE(mma8452_hp_filter_cutoff[0][0]), val, val2);
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}
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static int mma8452_read_hp_filter(struct mma8452_data *data, int *hz, int *uHz)
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{
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int i, ret;
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int j, i, ret;
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ret = i2c_smbus_read_byte_data(data->client, MMA8452_HP_FILTER_CUTOFF);
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if (ret < 0)
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return ret;
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i = mma8452_get_odr_index(data);
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j = mma8452_get_power_mode(data);
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if (j < 0)
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return j;
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ret &= MMA8452_HP_FILTER_CUTOFF_SEL_MASK;
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*hz = mma8452_hp_filter_cutoff[i][ret][0];
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*uHz = mma8452_hp_filter_cutoff[i][ret][1];
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*hz = mma8452_hp_filter_cutoff[j][i][ret][0];
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*uHz = mma8452_hp_filter_cutoff[j][i][ret][1];
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return 0;
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}
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@ -414,6 +506,15 @@ static int mma8452_read_raw(struct iio_dev *indio_dev,
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}
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return IIO_VAL_INT_PLUS_MICRO;
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case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
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ret = mma8452_get_power_mode(data);
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if (ret < 0)
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return ret;
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i = mma8452_get_odr_index(data);
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*val = mma8452_os_ratio[ret][i];
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return IIO_VAL_INT;
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}
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return -EINVAL;
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@ -480,6 +581,21 @@ fail:
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return ret;
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}
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static int mma8452_set_power_mode(struct mma8452_data *data, u8 mode)
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{
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int reg;
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reg = i2c_smbus_read_byte_data(data->client,
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MMA8452_CTRL_REG2);
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if (reg < 0)
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return reg;
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reg &= ~MMA8452_CTRL_REG2_MODS_MASK;
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reg |= mode << MMA8452_CTRL_REG2_MODS_SHIFT;
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return mma8452_change_config(data, MMA8452_CTRL_REG2, reg);
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}
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/* returns >0 if in freefall mode, 0 if not or <0 if an error occurred */
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static int mma8452_freefall_mode_enabled(struct mma8452_data *data)
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{
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@ -597,6 +713,14 @@ static int mma8452_write_raw(struct iio_dev *indio_dev,
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return mma8452_change_config(data, MMA8452_DATA_CFG,
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data->data_cfg);
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case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
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ret = mma8452_get_odr_index(data);
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for (i = 0; i < ARRAY_SIZE(mma8452_os_ratio); i++) {
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if (mma8452_os_ratio[i][ret] == val)
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return mma8452_set_power_mode(data, i);
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}
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default:
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return -EINVAL;
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}
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@ -610,7 +734,7 @@ static int mma8452_read_thresh(struct iio_dev *indio_dev,
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int *val, int *val2)
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{
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struct mma8452_data *data = iio_priv(indio_dev);
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int ret, us;
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int ret, us, power_mode;
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switch (info) {
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case IIO_EV_INFO_VALUE:
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@ -629,7 +753,11 @@ static int mma8452_read_thresh(struct iio_dev *indio_dev,
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if (ret < 0)
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return ret;
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us = ret * mma8452_transient_time_step_us[
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power_mode = mma8452_get_power_mode(data);
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if (power_mode < 0)
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return power_mode;
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us = ret * mma8452_transient_time_step_us[power_mode][
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mma8452_get_odr_index(data)];
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*val = us / USEC_PER_SEC;
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*val2 = us % USEC_PER_SEC;
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@ -677,8 +805,12 @@ static int mma8452_write_thresh(struct iio_dev *indio_dev,
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val);
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case IIO_EV_INFO_PERIOD:
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ret = mma8452_get_power_mode(data);
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if (ret < 0)
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return ret;
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steps = (val * USEC_PER_SEC + val2) /
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mma8452_transient_time_step_us[
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mma8452_transient_time_step_us[ret][
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mma8452_get_odr_index(data)];
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if (steps < 0 || steps > 0xff)
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@ -978,7 +1110,8 @@ static struct attribute_group mma8452_event_attribute_group = {
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BIT(IIO_CHAN_INFO_CALIBBIAS), \
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.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
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BIT(IIO_CHAN_INFO_SCALE) | \
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BIT(IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY), \
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BIT(IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY) | \
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BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
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.scan_index = idx, \
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.scan_type = { \
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.sign = 's', \
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@ -998,7 +1131,8 @@ static struct attribute_group mma8452_event_attribute_group = {
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
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BIT(IIO_CHAN_INFO_CALIBBIAS), \
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.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
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BIT(IIO_CHAN_INFO_SCALE), \
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BIT(IIO_CHAN_INFO_SCALE) | \
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BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
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.scan_index = idx, \
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.scan_type = { \
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.sign = 's', \
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@ -1171,6 +1305,7 @@ static struct attribute *mma8452_attributes[] = {
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&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
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&iio_dev_attr_in_accel_scale_available.dev_attr.attr,
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&iio_dev_attr_in_accel_filter_high_pass_3db_frequency_available.dev_attr.attr,
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&iio_dev_attr_in_accel_oversampling_ratio_available.dev_attr.attr,
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NULL
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};
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