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Date: Wed, 4 May 2016 11:47:21 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Martin Kepplinger <martink@...teo.de>, knaack.h@....de,
lars@...afoo.de, pmeerw@...erw.net,
christoph.muellner@...obroma-systems.com, mfuzzey@...keon.com
Cc: linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: mma8452: add support for oversampling ratio
On 25/04/16 13:08, Martin Kepplinger wrote:
> 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@...teo.de>
> Signed-off-by: Christoph Muellner <christoph.muellner@...obroma-systems.com>
Looks good to me - applied to the togreg branch of iio.git which will
sometime before the end of the weekend get pushed out as testing for the
autobuilders to play with it.
Thanks,
Jonathan
> ---
> This is meant to get merged for v4.8 to have time for review and possibly
> testing by others.
>
> thanks,
> martin
>
>
> drivers/iio/accel/mma8452.c | 185 ++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 160 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
> index e225d3c..458c827 100644
> --- a/drivers/iio/accel/mma8452.c
> +++ b/drivers/iio/accel/mma8452.c
> @@ -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)
> @@ -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 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 @@ fail:
> 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
> };
>
>
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