iio: imu: adis_trigger: Allow level interrupts for FIFO readings

Currently, adis library allows configuration only for edge interrupts,
needed for data ready sampling.
This patch removes the restriction for level interrupts for devices
which have FIFO support.
Furthermore, in case of devices which have FIFO support,
devm_request_threaded_irq is used for interrupt allocation, to avoid
flooding the processor with the FIFO watermark level interrupt, which
is active until enough data has been read from the FIFO.
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Signed-off-by: Ramona Gradinariu <ramona.bolboaca13@gmail.com>
Link: https://lore.kernel.org/r/20240527142618.275897-7-ramona.bolboaca13@gmail.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/adis_trigger.c

@@ -34,17 +34,24 @@ static int adis_validate_irq_flag(struct adis *adis)
 	if (adis->data->unmasked_drdy)
 		adis->irq_flag |= IRQF_NO_AUTOEN;
 	/*
-	 * Typically this devices have data ready either on the rising edge or
-	 * on the falling edge of the data ready pin. This checks enforces that
-	 * one of those is set in the drivers... It defaults to
-	 * IRQF_TRIGGER_RISING for backward compatibility with devices that
-	 * don't support changing the pin polarity.
+	 * Typically adis devices without FIFO have data ready either on the
+	 * rising edge or on the falling edge of the data ready pin.
+	 * IMU devices with FIFO support have the watermark pin level driven
+	 * either high or low when the FIFO is filled with the desired number
+	 * of samples.
+	 * It defaults to IRQF_TRIGGER_RISING for backward compatibility with
+	 * devices that don't support changing the pin polarity.
 	 */
 	if (direction == IRQF_TRIGGER_NONE) {
 		adis->irq_flag |= IRQF_TRIGGER_RISING;
 		return 0;
 	} else if (direction != IRQF_TRIGGER_RISING &&
-		   direction != IRQF_TRIGGER_FALLING) {
+		   direction != IRQF_TRIGGER_FALLING && !adis->data->has_fifo) {
+		dev_err(&adis->spi->dev, "Invalid IRQ mask: %08lx\n",
+			adis->irq_flag);
+		return -EINVAL;
+	} else if (direction != IRQF_TRIGGER_HIGH &&
+		   direction != IRQF_TRIGGER_LOW && adis->data->has_fifo) {
 		dev_err(&adis->spi->dev, "Invalid IRQ mask: %08lx\n",
 			adis->irq_flag);
 		return -EINVAL;
@@ -77,6 +84,14 @@ int devm_adis_probe_trigger(struct adis *adis, struct iio_dev *indio_dev)
 	if (ret)
 		return ret;
 
+	if (adis->data->has_fifo)
+		ret = devm_request_threaded_irq(&adis->spi->dev, adis->spi->irq,
+						NULL,
+						&iio_trigger_generic_data_rdy_poll,
+						adis->irq_flag | IRQF_ONESHOT,
+						indio_dev->name,
+						adis->trig);
+	else
 		ret = devm_request_irq(&adis->spi->dev, adis->spi->irq,
 				       &iio_trigger_generic_data_rdy_poll,
 				       adis->irq_flag,

include/linux/iio/imu/adis.h

@@ -85,6 +85,7 @@ struct adis_data {
 	bool unmasked_drdy;
 
 	bool has_paging;
+	bool has_fifo;
 
 	unsigned int burst_reg_cmd;
 	unsigned int burst_len;