From 8a09054f3e8afd0521309b15baab716fa7454785 Mon Sep 17 00:00:00 2001 From: Ahmad Fatoum Date: Mon, 25 Jan 2021 20:48:23 +0100 Subject: [PATCH] iio: adc: stm32-adc: enable timestamping for non-DMA usage For non-DMA usage, we have an easy way to associate a timestamp with a sample: iio_pollfunc_store_time stores a timestamp in the primary trigger IRQ handler and stm32_adc_trigger_handler runs in the IRQ thread to push out the buffer along with the timestamp. For this to work, the driver needs to register an IIO_TIMESTAMP channel. Do this. For DMA, it's not as easy, because we don't push the buffers out of stm32_adc_trigger, but out of stm32_adc_dma_buffer_done, which runs in a tasklet scheduled after a DMA completion. Preferably, the DMA controller would copy us the timestamp into that buffer as well. Until this is implemented, restrict timestamping support to only PIO. For low-frequency sampling, PIO is probably good enough. Cc: Holger Assmann Acked-by: Fabrice Gasnier Signed-off-by: Ahmad Fatoum Link: https://lore.kernel.org/r/20210125194824.30549-1-a.fatoum@pengutronix.de Signed-off-by: Jonathan Cameron --- drivers/iio/adc/stm32-adc.c | 39 +++++++++++++++++++++++++++++++-------- 1 file changed, 31 insertions(+), 8 deletions(-) diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c index f7c53cea509a..b25386b19373 100644 --- a/drivers/iio/adc/stm32-adc.c +++ b/drivers/iio/adc/stm32-adc.c @@ -177,7 +177,7 @@ struct stm32_adc_cfg { * @offset: ADC instance register offset in ADC block * @cfg: compatible configuration data * @completion: end of single conversion completion - * @buffer: data buffer + * @buffer: data buffer + 8 bytes for timestamp if enabled * @clk: clock for this adc instance * @irq: interrupt for this adc instance * @lock: spinlock @@ -200,7 +200,7 @@ struct stm32_adc { u32 offset; const struct stm32_adc_cfg *cfg; struct completion completion; - u16 buffer[STM32_ADC_MAX_SQ]; + u16 buffer[STM32_ADC_MAX_SQ + 4] __aligned(8); struct clk *clk; int irq; spinlock_t lock; /* interrupt lock */ @@ -1714,7 +1714,7 @@ static void stm32_adc_chan_init_one(struct iio_dev *indio_dev, } } -static int stm32_adc_chan_of_init(struct iio_dev *indio_dev) +static int stm32_adc_chan_of_init(struct iio_dev *indio_dev, bool timestamping) { struct device_node *node = indio_dev->dev.of_node; struct stm32_adc *adc = iio_priv(indio_dev); @@ -1762,6 +1762,9 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev) return -EINVAL; } + if (timestamping) + num_channels++; + channels = devm_kcalloc(&indio_dev->dev, num_channels, sizeof(struct iio_chan_spec), GFP_KERNEL); if (!channels) @@ -1812,6 +1815,19 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev) stm32_adc_smpr_init(adc, channels[i].channel, smp); } + if (timestamping) { + struct iio_chan_spec *timestamp = &channels[scan_index]; + + timestamp->type = IIO_TIMESTAMP; + timestamp->channel = -1; + timestamp->scan_index = scan_index; + timestamp->scan_type.sign = 's'; + timestamp->scan_type.realbits = 64; + timestamp->scan_type.storagebits = 64; + + scan_index++; + } + indio_dev->num_channels = scan_index; indio_dev->channels = channels; @@ -1871,6 +1887,7 @@ static int stm32_adc_probe(struct platform_device *pdev) struct device *dev = &pdev->dev; irqreturn_t (*handler)(int irq, void *p) = NULL; struct stm32_adc *adc; + bool timestamping = false; int ret; if (!pdev->dev.of_node) @@ -1927,16 +1944,22 @@ static int stm32_adc_probe(struct platform_device *pdev) if (ret < 0) return ret; - ret = stm32_adc_chan_of_init(indio_dev); - if (ret < 0) - return ret; - ret = stm32_adc_dma_request(dev, indio_dev); if (ret < 0) return ret; - if (!adc->dma_chan) + if (!adc->dma_chan) { + /* For PIO mode only, iio_pollfunc_store_time stores a timestamp + * in the primary trigger IRQ handler and stm32_adc_trigger_handler + * runs in the IRQ thread to push out buffer along with timestamp. + */ handler = &stm32_adc_trigger_handler; + timestamping = true; + } + + ret = stm32_adc_chan_of_init(indio_dev, timestamping); + if (ret < 0) + goto err_dma_disable; ret = iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time, handler, -- 2.11.0