From 5dc11e810676ec4a5acb4423ccd33314bf74f4e5 Mon Sep 17 00:00:00 2001 From: Vignesh R Date: Tue, 31 Mar 2015 16:42:37 +0530 Subject: iio: adc: ti_am335x_adc: make sample delay, open delay, averaging DT parameters Add optional DT properties to set open delay, sample delay and number of averages per sample for each adc step. Open delay, sample delay and averaging are some of the parameters that affect the sampling rate and accuracy of the sample. Making these parameters configurable via DT will help in balancing speed vs accuracy. Signed-off-by: Vignesh R Signed-off-by: Jonathan Cameron --- drivers/iio/adc/ti_am335x_adc.c | 54 ++++++++++++++++++++++++++++++++++++----- 1 file changed, 48 insertions(+), 6 deletions(-) (limited to 'drivers/iio') diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c index 42e444044ea5..942320e32753 100644 --- a/drivers/iio/adc/ti_am335x_adc.c +++ b/drivers/iio/adc/ti_am335x_adc.c @@ -37,6 +37,7 @@ struct tiadc_device { u8 channel_step[8]; int buffer_en_ch_steps; u16 data[8]; + u32 open_delay[8], sample_delay[8], step_avg[8]; }; static unsigned int tiadc_readl(struct tiadc_device *adc, unsigned int reg) @@ -85,6 +86,7 @@ static u32 get_adc_step_bit(struct tiadc_device *adc_dev, int chan) static void tiadc_step_config(struct iio_dev *indio_dev) { struct tiadc_device *adc_dev = iio_priv(indio_dev); + struct device *dev = adc_dev->mfd_tscadc->dev; unsigned int stepconfig; int i, steps = 0; @@ -98,20 +100,47 @@ static void tiadc_step_config(struct iio_dev *indio_dev) * needs to be given to ADC to digitalize data. */ - if (iio_buffer_enabled(indio_dev)) - stepconfig = STEPCONFIG_AVG_16 | STEPCONFIG_FIFO1 - | STEPCONFIG_MODE_SWCNT; - else - stepconfig = STEPCONFIG_AVG_16 | STEPCONFIG_FIFO1; for (i = 0; i < adc_dev->channels; i++) { int chan; chan = adc_dev->channel_line[i]; + + if (adc_dev->step_avg[i] > STEPCONFIG_AVG_16) { + dev_warn(dev, "chan %d step_avg truncating to %d\n", + chan, STEPCONFIG_AVG_16); + adc_dev->step_avg[i] = STEPCONFIG_AVG_16; + } + + if (adc_dev->step_avg[i]) + stepconfig = + STEPCONFIG_AVG(ffs(adc_dev->step_avg[i]) - 1) | + STEPCONFIG_FIFO1; + else + stepconfig = STEPCONFIG_FIFO1; + + if (iio_buffer_enabled(indio_dev)) + stepconfig |= STEPCONFIG_MODE_SWCNT; + tiadc_writel(adc_dev, REG_STEPCONFIG(steps), stepconfig | STEPCONFIG_INP(chan)); + + if (adc_dev->open_delay[i] > STEPDELAY_OPEN_MASK) { + dev_warn(dev, "chan %d open delay truncating to 0x3FFFF\n", + chan); + adc_dev->open_delay[i] = STEPDELAY_OPEN_MASK; + } + + if (adc_dev->sample_delay[i] > 0xFF) { + dev_warn(dev, "chan %d sample delay truncating to 0xFF\n", + chan); + adc_dev->sample_delay[i] = 0xFF; + } + tiadc_writel(adc_dev, REG_STEPDELAY(steps), - STEPCONFIG_OPENDLY); + STEPDELAY_OPEN(adc_dev->open_delay[i]) | + STEPDELAY_SAMPLE(adc_dev->sample_delay[i])); + adc_dev->channel_step[i] = steps; steps++; } @@ -406,9 +435,22 @@ static int tiadc_parse_dt(struct platform_device *pdev, of_property_for_each_u32(node, "ti,adc-channels", prop, cur, val) { adc_dev->channel_line[channels] = val; + + /* Set Default values for optional DT parameters */ + adc_dev->open_delay[channels] = STEPCONFIG_OPENDLY; + adc_dev->sample_delay[channels] = STEPCONFIG_SAMPLEDLY; + adc_dev->step_avg[channels] = 16; + channels++; } + of_property_read_u32_array(node, "ti,chan-step-avg", + adc_dev->step_avg, channels); + of_property_read_u32_array(node, "ti,chan-step-opendelay", + adc_dev->open_delay, channels); + of_property_read_u32_array(node, "ti,chan-step-sampledelay", + adc_dev->sample_delay, channels); + adc_dev->channels = channels; return 0; } -- cgit v1.2.3