On 17/02/16 17:52, Gregor Boirie wrote:
> Add support for setting and retrieving OverSampling Rate independently for
> each of the temperature and pressure channels. This allows userspace to
> fine tune hardware sampling process according to the following tradeoffs :
> * the higher the OSR, the finer the resolution ;
> * the higher the OSR, the lower the noise ;
> BUT:
> * the higher the OSR, the larger the drift ;
> * the higher the OSR, the longer the response time, i.e. less samples per
> unit of time.
>
> Signed-off-by: Gregor Boirie <gregor.boirie@xxxxxxxxxx>
Whilst this looks fine to me - it's complex enough that I'd like Tomasz to take
a look at it before I apply (ideally anyway!)
> ---
> drivers/iio/pressure/ms5611.h | 20 ++++---
> drivers/iio/pressure/ms5611_core.c | 105 ++++++++++++++++++++++++++++++++++++-
> drivers/iio/pressure/ms5611_i2c.c | 12 ++---
> drivers/iio/pressure/ms5611_spi.c | 19 +++----
> 4 files changed, 133 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/iio/pressure/ms5611.h b/drivers/iio/pressure/ms5611.h
> index 8b08e4b..b07897f 100644
> --- a/drivers/iio/pressure/ms5611.h
> +++ b/drivers/iio/pressure/ms5611.h
> @@ -19,12 +19,6 @@
> #define MS5611_RESET 0x1e
> #define MS5611_READ_ADC 0x00
> #define MS5611_READ_PROM_WORD 0xA0
> -#define MS5611_START_TEMP_CONV 0x58
> -#define MS5611_START_PRESSURE_CONV 0x48
> -
> -#define MS5611_CONV_TIME_MIN 9040
> -#define MS5611_CONV_TIME_MAX 10000
> -
> #define MS5611_PROM_WORDS_NB 8
>
> enum {
> @@ -39,10 +33,24 @@ struct ms5611_chip_info {
> s32 *temp, s32 *pressure);
> };
>
> +/*
> + * OverSampling Rate descriptor.
> + * Warning: cmd MUST be kept aligned on a word boundary (see
> + * m5611_spi_read_adc_temp_and_pressure in ms5611_spi.c).
> + */
> +struct ms5611_osr {
> + unsigned long conv_usec;
> + uint8_t cmd;
> + unsigned short rate;
> +};
> +
> struct ms5611_state {
> void *client;
> struct mutex lock;
>
> + const struct ms5611_osr *pressure_osr;
> + const struct ms5611_osr *temp_osr;
> +
> int (*reset)(struct device *dev);
> int (*read_prom_word)(struct device *dev, int index, u16 *word);
> int (*read_adc_temp_and_pressure)(struct device *dev,
> diff --git a/drivers/iio/pressure/ms5611_core.c b/drivers/iio/pressure/ms5611_core.c
> index 992ad8d..06d453c 100644
> --- a/drivers/iio/pressure/ms5611_core.c
> +++ b/drivers/iio/pressure/ms5611_core.c
> @@ -18,11 +18,44 @@
> #include <linux/delay.h>
> #include <linux/regulator/consumer.h>
>
> +#include <linux/iio/sysfs.h>
> #include <linux/iio/buffer.h>
> #include <linux/iio/triggered_buffer.h>
> #include <linux/iio/trigger_consumer.h>
> #include "ms5611.h"
>
> +#define MS5611_INIT_OSR(_cmd, _conv_usec, _rate) \
> + { .cmd = _cmd, .conv_usec = _conv_usec, .rate = _rate }
> +
> +static const struct ms5611_osr ms5611_avail_pressure_osr[] = {
> + MS5611_INIT_OSR(0x40, 600, 256),
> + MS5611_INIT_OSR(0x42, 1170, 512),
> + MS5611_INIT_OSR(0x44, 2280, 1024),
> + MS5611_INIT_OSR(0x46, 4540, 2048),
> + MS5611_INIT_OSR(0x48, 9040, 4096)
> +};
> +
> +static const struct ms5611_osr ms5611_avail_temp_osr[] = {
> + MS5611_INIT_OSR(0x50, 600, 256),
> + MS5611_INIT_OSR(0x52, 1170, 512),
> + MS5611_INIT_OSR(0x54, 2280, 1024),
> + MS5611_INIT_OSR(0x56, 4540, 2048),
> + MS5611_INIT_OSR(0x58, 9040, 4096)
> +};
> +
> +static const char ms5611_show_osr[] = "256 512 1024 2048 4096";
> +
> +static IIO_CONST_ATTR(oversampling_ratio_available, ms5611_show_osr);
> +
> +static struct attribute *ms5611_attributes[] = {
> + &iio_const_attr_oversampling_ratio_available.dev_attr.attr,
> + NULL,
> +};
> +
> +static const struct attribute_group ms5611_attribute_group = {
> + .attrs = ms5611_attributes,
> +};
> +
> static bool ms5611_prom_is_valid(u16 *prom, size_t len)
> {
> int i, j;
> @@ -239,11 +272,70 @@ static int ms5611_read_raw(struct iio_dev *indio_dev,
> default:
> return -EINVAL;
> }
> + case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> + if (chan->type != IIO_TEMP && chan->type != IIO_PRESSURE)
> + break;
> + mutex_lock(&st->lock);
> + if (chan->type == IIO_TEMP)
> + *val = (int) st->temp_osr->rate;
> + else
> + *val = (int) st->pressure_osr->rate;
> + mutex_unlock(&st->lock);
> + return IIO_VAL_INT;
> }
>
> return -EINVAL;
> }
>
> +static const struct ms5611_osr* ms5611_find_osr(int rate,
> + const struct ms5611_osr *osr,
> + size_t count)
> +{
> + unsigned int r;
> +
> + for (r = 0; r < count; r++)
> + if ((unsigned short) rate == osr[r].rate)
> + break;
> + if (r >= count)
> + return NULL;
> + return &osr[r];
> +}
> +
> +static int ms5611_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int val, int val2, long mask)
> +{
> + struct ms5611_state *st = iio_priv(indio_dev);
> + const struct ms5611_osr *osr = NULL;
> +
> + if (mask != IIO_CHAN_INFO_OVERSAMPLING_RATIO)
> + return -EINVAL;
> +
> + if (chan->type == IIO_TEMP)
> + osr = ms5611_find_osr(val, ms5611_avail_temp_osr,
> + ARRAY_SIZE(ms5611_avail_temp_osr));
> + else if (chan->type == IIO_PRESSURE)
> + osr = ms5611_find_osr(val, ms5611_avail_pressure_osr,
> + ARRAY_SIZE(ms5611_avail_pressure_osr));
> + if (!osr)
> + return -EINVAL;
> +
> + mutex_lock(&st->lock);
> +
> + if (iio_buffer_enabled(indio_dev)) {
> + mutex_unlock(&st->lock);
> + return -EBUSY;
> + }
> +
> + if (chan->type == IIO_TEMP)
> + st->temp_osr = osr;
> + else
> + st->pressure_osr = osr;
> +
> + mutex_unlock(&st->lock);
> + return 0;
> +}
> +
> static const unsigned long ms5611_scan_masks[] = {0x3, 0};
>
> static struct ms5611_chip_info chip_info_tbl[] = {
> @@ -259,7 +351,8 @@ static const struct iio_chan_spec ms5611_channels[] = {
> {
> .type = IIO_PRESSURE,
> .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
> - BIT(IIO_CHAN_INFO_SCALE),
> + BIT(IIO_CHAN_INFO_SCALE) |
> + BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
> .scan_index = 0,
> .scan_type = {
> .sign = 's',
> @@ -271,7 +364,8 @@ static const struct iio_chan_spec ms5611_channels[] = {
> {
> .type = IIO_TEMP,
> .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
> - BIT(IIO_CHAN_INFO_SCALE),
> + BIT(IIO_CHAN_INFO_SCALE) |
> + BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
> .scan_index = 1,
> .scan_type = {
> .sign = 's',
> @@ -285,6 +379,8 @@ static const struct iio_chan_spec ms5611_channels[] = {
>
> static const struct iio_info ms5611_info = {
> .read_raw = &ms5611_read_raw,
> + .write_raw = &ms5611_write_raw,
> + .attrs = &ms5611_attribute_group,
> .driver_module = THIS_MODULE,
> };
>
> @@ -319,6 +415,11 @@ int ms5611_probe(struct iio_dev *indio_dev, struct device *dev,
>
> mutex_init(&st->lock);
> st->chip_info = &chip_info_tbl[type];
> + st->temp_osr =
> + &ms5611_avail_temp_osr[ARRAY_SIZE(ms5611_avail_temp_osr) - 1];
> + st->pressure_osr =
> + &ms5611_avail_pressure_osr[ARRAY_SIZE(ms5611_avail_pressure_osr)
> + - 1];
> indio_dev->dev.parent = dev;
> indio_dev->name = name;
> indio_dev->info = &ms5611_info;
> diff --git a/drivers/iio/pressure/ms5611_i2c.c b/drivers/iio/pressure/ms5611_i2c.c
> index ae67539..b482ca4 100644
> --- a/drivers/iio/pressure/ms5611_i2c.c
> +++ b/drivers/iio/pressure/ms5611_i2c.c
> @@ -62,23 +62,23 @@ static int ms5611_i2c_read_adc_temp_and_pressure(struct device *dev,
> {
> int ret;
> struct ms5611_state *st = iio_priv(dev_to_iio_dev(dev));
> + const struct ms5611_osr *osr = st->temp_osr;
>
> - ret = i2c_smbus_write_byte(st->client, MS5611_START_TEMP_CONV);
> + ret = i2c_smbus_write_byte(st->client, osr->cmd);
> if (ret < 0)
> return ret;
>
> - usleep_range(MS5611_CONV_TIME_MIN, MS5611_CONV_TIME_MAX);
> -
> + usleep_range(osr->conv_usec, osr->conv_usec + (osr->conv_usec / 10UL));
> ret = ms5611_i2c_read_adc(st, temp);
> if (ret < 0)
> return ret;
>
> - ret = i2c_smbus_write_byte(st->client, MS5611_START_PRESSURE_CONV);
> + osr = st->pressure_osr;
> + ret = i2c_smbus_write_byte(st->client, osr->cmd);
> if (ret < 0)
> return ret;
>
> - usleep_range(MS5611_CONV_TIME_MIN, MS5611_CONV_TIME_MAX);
> -
> + usleep_range(osr->conv_usec, osr->conv_usec + (osr->conv_usec / 10UL));
> return ms5611_i2c_read_adc(st, pressure);
> }
>
> diff --git a/drivers/iio/pressure/ms5611_spi.c b/drivers/iio/pressure/ms5611_spi.c
> index 5cc009e..aa6cf2d 100644
> --- a/drivers/iio/pressure/ms5611_spi.c
> +++ b/drivers/iio/pressure/ms5611_spi.c
> @@ -55,28 +55,29 @@ static int ms5611_spi_read_adc(struct device *dev, s32 *val)
> static int ms5611_spi_read_adc_temp_and_pressure(struct device *dev,
> s32 *temp, s32 *pressure)
> {
> - u8 cmd;
> int ret;
> struct ms5611_state *st = iio_priv(dev_to_iio_dev(dev));
> + const struct ms5611_osr *osr = st->temp_osr;
>
> - cmd = MS5611_START_TEMP_CONV;
> - ret = spi_write_then_read(st->client, &cmd, 1, NULL, 0);
> + /*
> + * Warning: &osr->cmd MUST be aligned on a word boundary since used as
> + * 2nd argument (void*) of spi_write_then_read.
> + */
> + ret = spi_write_then_read(st->client, &osr->cmd, 1, NULL, 0);
> if (ret < 0)
> return ret;
>
> - usleep_range(MS5611_CONV_TIME_MIN, MS5611_CONV_TIME_MAX);
> -
> + usleep_range(osr->conv_usec, osr->conv_usec + (osr->conv_usec / 10UL));
> ret = ms5611_spi_read_adc(dev, temp);
> if (ret < 0)
> return ret;
>
> - cmd = MS5611_START_PRESSURE_CONV;
> - ret = spi_write_then_read(st->client, &cmd, 1, NULL, 0);
> + osr = st->pressure_osr;
> + ret = spi_write_then_read(st->client, &osr->cmd, 1, NULL, 0);
> if (ret < 0)
> return ret;
>
> - usleep_range(MS5611_CONV_TIME_MIN, MS5611_CONV_TIME_MAX);
> -
> + usleep_range(osr->conv_usec, osr->conv_usec + (osr->conv_usec / 10UL));
> return ms5611_spi_read_adc(dev, pressure);
> }
>
>
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