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Fabrice Gasnier authored
DFSDM conversions can be launched continuously, or using various triggers: - by software - hardware triggers (e.g. like in stm32-adc: TIM, LPTIM, EXTI) - synchronously with DFSDM filter 0. e.g. for filters 1, 2 Launching conversions can be done using two methods: a - injected: - scan mode can be used to convert several channels each time a trigger occurs. - When not is scan mode, channels are converted in sequence, one upon each trigger. b - regular: - supports software triggers or synchronous with filter 0 - single or continuous conversions This patch finalizes DFSDM operating modes using IIO buffer modes: - INDIO_BUFFER_SOFTWARE: regular continuous conversions (no trigger) but limited to 1 channel. Users must set sampling frequency in this case. For filters > 1, conversions can be started synchronously with filter 0. - INDIO_BUFFER_TRIGGERED: triggered conversions uses injected mode for launching conversions. DFSDM can use hardware triggers (e.g. STM32 timer or lptimer), so add INDIO_HARDWARE_TRIGGERED to supported modes. - INDIO_DIRECT_MODE: Only support DMA-based buffer modes. In case no DMA is available, only support single conversions. From userland perspective, to summarize various use cases: 1 - single conversion on any filter: $ cd iio:deviceX $ cat in_voltageY_raw This uses regular a conversion (not continuous) 2 - Using sampling frequency without trigger (single channel, buffer) $ cd iio:deviceX $ echo 100 > sampling_frequency $ echo "" > trigger/current_trigger $ echo 1 > scan_elements/in_voltageY_en $ echo 1 > buffer/enable This uses regular conversion in continuous mode (Frequency is achieved by tuning filter parameters) 3 - sync mode with filter 0: other filters can be converted when using "st,filter0-sync" dt property. The conversions will get started at the same time as filter 0. So for any filters > 1: $ cd iio:deviceX $ echo 100 > sampling_frequency $ echo "" > trigger/current_trigger $ echo 1 > scan_elements/in_voltageY_en $ echo 1 > buffer/enable Then start filter 0 as in 2 above. 4 - Using a hardware trigger (with one channel): - check trigger, configure it: $ cat /sys/bus/iio/devices/trigger1/name tim6_trgo $ echo 100 > /sys/bus/iio/devices/trigger1/sampling_frequency - go to any filter: $ echo 1 > scan_elements/in_voltageY_en $ echo tim6_trgo > trigger/current_trigger $ echo 1 > buffer/enable This uses injected conversion as it uses a hardware trigger (without scan) 5 - Using a hardware trigger (with 2+ channel): Same as in 4/ above, but enable two or more channels in scan_elements. This uses injected conversion as it uses a hardware trigger (with scan mode) Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
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