Commit 8a09054f authored by Ahmad Fatoum's avatar Ahmad Fatoum Committed by Jonathan Cameron
Browse files

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 <has@pengutronix.de>
Acked-by: default avatarFabrice Gasnier <fabrice.gasnier@foss.st.com>
Signed-off-by: default avatarAhmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.kernel.org/r/20210125194824.30549-1-a.fatoum@pengutronix.de


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent 6c3b6153

drivers/iio/adc/stm32-adc.c

+31 −8
Original line number Diff line number Diff line
@@ -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,