iio: ti-adc0832: add triggered buffer support

This adds triggered buffer support for the ti-adc0832 driver.  Tested with
ADC0831 and ADC0832 by using SYSFS trigger.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Hartmut Knaack <knaack.h@gmx.de>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Peter Meerwald-Stadler <pmeerw@pmeerw.net>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/adc/Kconfig

@@ -459,6 +459,8 @@ config TI_ADC081C
 config TI_ADC0832
 	tristate "Texas Instruments ADC0831/ADC0832/ADC0834/ADC0838"
 	depends on SPI
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
 	help
 	  If you say yes here you get support for Texas Instruments ADC0831,
 	  ADC0832, ADC0834, ADC0838 ADC chips.

drivers/iio/adc/ti-adc0832.c

@@ -14,6 +14,10 @@
 #include <linux/spi/spi.h>
 #include <linux/iio/iio.h>
 #include <linux/regulator/consumer.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger_consumer.h>
 
 enum {
 	adc0831,
@@ -38,10 +42,16 @@ struct adc0832 {
 		.indexed = 1,						\
 		.channel = chan,					\
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
-		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE)	\
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+		.scan_index = chan,					\
+		.scan_type = {						\
+			.sign = 'u',					\
+			.realbits = 8,					\
+			.storagebits = 8,				\
+		},							\
 	}
 
-#define ADC0832_VOLTAGE_CHANNEL_DIFF(chan1, chan2)			\
+#define ADC0832_VOLTAGE_CHANNEL_DIFF(chan1, chan2, si)			\
 	{								\
 		.type = IIO_VOLTAGE,					\
 		.indexed = 1,						\
@@ -49,18 +59,26 @@ struct adc0832 {
 		.channel2 = (chan2),					\
 		.differential = 1,					\
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
-		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE)	\
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+		.scan_index = si,					\
+		.scan_type = {						\
+			.sign = 'u',					\
+			.realbits = 8,					\
+			.storagebits = 8,				\
+		},							\
 	}
 
 static const struct iio_chan_spec adc0831_channels[] = {
-	ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1),
+	ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 0),
+	IIO_CHAN_SOFT_TIMESTAMP(1),
 };
 
 static const struct iio_chan_spec adc0832_channels[] = {
 	ADC0832_VOLTAGE_CHANNEL(0),
 	ADC0832_VOLTAGE_CHANNEL(1),
-	ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1),
-	ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0),
+	ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 2),
+	ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0, 3),
+	IIO_CHAN_SOFT_TIMESTAMP(4),
 };
 
 static const struct iio_chan_spec adc0834_channels[] = {
@@ -68,10 +86,11 @@ static const struct iio_chan_spec adc0834_channels[] = {
 	ADC0832_VOLTAGE_CHANNEL(1),
 	ADC0832_VOLTAGE_CHANNEL(2),
 	ADC0832_VOLTAGE_CHANNEL(3),
-	ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1),
-	ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0),
-	ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3),
-	ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2),
+	ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 4),
+	ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0, 5),
+	ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3, 6),
+	ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2, 7),
+	IIO_CHAN_SOFT_TIMESTAMP(8),
 };
 
 static const struct iio_chan_spec adc0838_channels[] = {
@@ -83,14 +102,15 @@ static const struct iio_chan_spec adc0838_channels[] = {
 	ADC0832_VOLTAGE_CHANNEL(5),
 	ADC0832_VOLTAGE_CHANNEL(6),
 	ADC0832_VOLTAGE_CHANNEL(7),
-	ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1),
-	ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0),
-	ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3),
-	ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2),
-	ADC0832_VOLTAGE_CHANNEL_DIFF(4, 5),
-	ADC0832_VOLTAGE_CHANNEL_DIFF(5, 4),
-	ADC0832_VOLTAGE_CHANNEL_DIFF(6, 7),
-	ADC0832_VOLTAGE_CHANNEL_DIFF(7, 6),
+	ADC0832_VOLTAGE_CHANNEL_DIFF(0, 1, 8),
+	ADC0832_VOLTAGE_CHANNEL_DIFF(1, 0, 9),
+	ADC0832_VOLTAGE_CHANNEL_DIFF(2, 3, 10),
+	ADC0832_VOLTAGE_CHANNEL_DIFF(3, 2, 11),
+	ADC0832_VOLTAGE_CHANNEL_DIFF(4, 5, 12),
+	ADC0832_VOLTAGE_CHANNEL_DIFF(5, 4, 13),
+	ADC0832_VOLTAGE_CHANNEL_DIFF(6, 7, 14),
+	ADC0832_VOLTAGE_CHANNEL_DIFF(7, 6, 15),
+	IIO_CHAN_SOFT_TIMESTAMP(16),
 };
 
 static int adc0831_adc_conversion(struct adc0832 *adc)
@@ -178,6 +198,42 @@ static const struct iio_info adc0832_info = {
 	.driver_module = THIS_MODULE,
 };
 
+static irqreturn_t adc0832_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct adc0832 *adc = iio_priv(indio_dev);
+	u8 data[24] = { }; /* 16x 1 byte ADC data + 8 bytes timestamp */
+	int scan_index;
+	int i = 0;
+
+	mutex_lock(&adc->lock);
+
+	for_each_set_bit(scan_index, indio_dev->active_scan_mask,
+			 indio_dev->masklength) {
+		const struct iio_chan_spec *scan_chan =
+				&indio_dev->channels[scan_index];
+		int ret = adc0832_adc_conversion(adc, scan_chan->channel,
+						 scan_chan->differential);
+		if (ret < 0) {
+			dev_warn(&adc->spi->dev,
+				 "failed to get conversion data\n");
+			goto out;
+		}
+
+		data[i] = ret;
+		i++;
+	}
+	iio_push_to_buffers_with_timestamp(indio_dev, data,
+					   iio_get_time_ns(indio_dev));
+out:
+	mutex_unlock(&adc->lock);
+
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
 static int adc0832_probe(struct spi_device *spi)
 {
 	struct iio_dev *indio_dev;
@@ -233,9 +289,20 @@ static int adc0832_probe(struct spi_device *spi)
 
 	spi_set_drvdata(spi, indio_dev);
 
+	ret = iio_triggered_buffer_setup(indio_dev, NULL,
+					 adc0832_trigger_handler, NULL);
+	if (ret)
+		goto err_reg_disable;
+
 	ret = iio_device_register(indio_dev);
 	if (ret)
-		regulator_disable(adc->reg);
+		goto err_buffer_cleanup;
+
+	return 0;
+err_buffer_cleanup:
+	iio_triggered_buffer_cleanup(indio_dev);
+err_reg_disable:
+	regulator_disable(adc->reg);
 
 	return ret;
 }
@@ -246,6 +313,7 @@ static int adc0832_remove(struct spi_device *spi)
 	struct adc0832 *adc = iio_priv(indio_dev);
 
 	iio_device_unregister(indio_dev);
+	iio_triggered_buffer_cleanup(indio_dev);
 	regulator_disable(adc->reg);
 
 	return 0;