This can lead to repeated or skipped samples depending on the clock beat between the capture thread and the chip sampling clock, but will also spare reading/waiting for the Capture Ready Flag and improve the available i2c bandwidth for reading measurements.
Output of iio_info: ...snip... 4 device-specific attributes found: attr 0: in_oversampling_ratio value: 4 attr 1: in_allow_async_readout value: 0 attr 2: integration_time_available value: 140 204 332 588 1100 2116 4156 8244 attr 3: in_sampling_frequency value: 114 Signed-off-by: Marc Titinger <mtitin...@baylibre.com> --- drivers/iio/adc/ina2xx-iio.c | 48 ++++++++++++++++++++++++++++++++++++++------ 1 file changed, 42 insertions(+), 6 deletions(-) diff --git a/drivers/iio/adc/ina2xx-iio.c b/drivers/iio/adc/ina2xx-iio.c index 4a0026c..c153164 100644 --- a/drivers/iio/adc/ina2xx-iio.c +++ b/drivers/iio/adc/ina2xx-iio.c @@ -114,6 +114,7 @@ struct ina2xx_chip_info { int avg; int itb; /* Bus voltage integration time uS */ int its; /* Shunt voltage integration tim uS */ + bool allow_async_readout; }; static const struct ina2xx_config ina2xx_config[] = { @@ -335,6 +336,33 @@ _err: } +static ssize_t ina2xx_allow_async_readout_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct ina2xx_chip_info *chip = iio_priv(dev_to_iio_dev(dev)); + + return sprintf(buf, "%d\n", chip->allow_async_readout); +} + +static ssize_t ina2xx_allow_async_readout_store(struct device *dev, + struct device_attribute *attr, + const char *buf, size_t len) +{ + struct ina2xx_chip_info *chip = iio_priv(dev_to_iio_dev(dev)); + unsigned long val; + int ret; + + ret = kstrtoul((const char *) buf, 10, &val); + if (ret) + return -EINVAL; + + chip->allow_async_readout = !!val; + + return len; +} + + #define INA2XX_CHAN(_type, _index, _address) { \ .type = _type, \ .address = _address, \ @@ -402,11 +430,12 @@ static int ina2xx_work_buffer(struct iio_dev *indio_dev) * GPIO a triggered buffer could be used instead. * For now, we pay for that extra read of the ALERT register */ - do { - ret = regmap_read(chip->regmap, INA226_ALERT_MASK, - &alert); - if (ret < 0) - goto _err; + if (!chip->allow_async_readout) + do { + ret = regmap_read(chip->regmap, INA226_ALERT_MASK, + &alert); + if (ret < 0) + goto _err; alert &= INA266_CVRF; trace_printk("Conversion ready: %d\n", !!alert); @@ -457,7 +486,8 @@ static int ina2xx_capture_thread(void *data) * Poll a bit faster than the chip internal Fs, in case * we wish to sync with the conversion ready flag. */ - sampling_us -= 200; + if (!chip->allow_async_readout) + sampling_us -= 200; do { buffer_us = ina2xx_work_buffer(indio_dev); @@ -480,6 +510,7 @@ int ina2xx_buffer_enable(struct iio_dev *indio_dev) 1000000/sampling_us, chip->avg); trace_printk("Expected work period: %u us\n", sampling_us); + trace_printk("Async readout mode: %d\n", chip->allow_async_readout); prev_ns = iio_get_time_ns(); @@ -519,7 +550,12 @@ static int ina2xx_debug_reg(struct iio_dev *indio_dev, /* frequencies matching the cummulated integration times for vshunt and vbus */ static IIO_CONST_ATTR_INT_TIME_AVAIL("140 204 332 588 1100 2116 4156 8244"); +static IIO_DEVICE_ATTR(in_allow_async_readout, S_IRUGO | S_IWUSR, + ina2xx_allow_async_readout_show, + ina2xx_allow_async_readout_store, 0); + static struct attribute *ina2xx_attributes[] = { + &iio_dev_attr_in_allow_async_readout.dev_attr.attr, &iio_const_attr_integration_time_available.dev_attr.attr, NULL, }; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/