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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: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://lore.kernel.org/r/20210125194824.30549-1-a.fatoum@pengutronix.de
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Ahmad Fatoum 2021-01-25 20:48:23 +01:00 committed by Jonathan Cameron
parent 6c3b615379
commit 8a09054f3e
1 changed files with 31 additions and 8 deletions
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39
drivers/iio/adc/stm32-adc.c
View File

@ -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,