From a0e831653ef93912c442a6d30dcb29fe94ecf050 Mon Sep 17 00:00:00 2001 From: Miquel Raynal Date: Tue, 21 Sep 2021 13:54:04 +0200 Subject: [PATCH] iio: adc: max1027: Introduce an end of conversion helper For now this helper only waits for the maximum duration of a single conversion. In practice, a "temperature measurement" will take twice this time because it will also carry another analog conversion but as here we will only care about the temperature conversion which happens first, we can still only wait for a single sample and get the right data. This helper will soon be improved to properly handle the end of conversion interrupt as well as a higher number of samples. Signed-off-by: Miquel Raynal Link: https://lore.kernel.org/r/20210921115408.66711-13-miquel.raynal@bootlin.com Signed-off-by: Jonathan Cameron --- drivers/iio/adc/max1027.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c index 1748b96..009203d 100644 --- a/drivers/iio/adc/max1027.c +++ b/drivers/iio/adc/max1027.c @@ -60,6 +60,9 @@ #define MAX1027_NAVG_32 (0x03 << 2) #define MAX1027_AVG_EN BIT(4) +/* Device can achieve 300ksps so we assume a 3.33us conversion delay */ +#define MAX1027_CONVERSION_UDELAY 4 + enum max1027_id { max1027, max1029, @@ -272,6 +275,15 @@ struct max1027_state { u8 reg ____cacheline_aligned; }; +static int max1027_wait_eoc(struct iio_dev *indio_dev) +{ + unsigned int conversion_time = MAX1027_CONVERSION_UDELAY; + + usleep_range(conversion_time, conversion_time * 2); + + return 0; +} + /* Scan from chan 0 to the highest requested channel. Include temperature on demand. */ static int max1027_configure_chans_and_start(struct iio_dev *indio_dev) { @@ -331,9 +343,11 @@ static int max1027_read_single_value(struct iio_dev *indio_dev, /* * For an unknown reason, when we use the mode "10" (write * conversion register), the interrupt doesn't occur every time. - * So we just wait 1 ms. + * So we just wait the maximum conversion time and deliver the value. */ - mdelay(1); + ret = max1027_wait_eoc(indio_dev); + if (ret) + return ret; /* Read result */ ret = spi_read(st->spi, st->buffer, (chan->type == IIO_TEMP) ? 4 : 2); -- 2.7.4