[PATCH v8 3/3] iio: accel: adxl355: Add triggered buffer support

[Puranjay Mohan]

Provide a way for continuous data capture by setting up buffer support. The
data ready signal exposed at the DRDY pin of the ADXL355 is exploited as
a hardware interrupt which triggers to fill the buffer.

Signed-off-by: Puranjay Mohan <puranjay12@xxxxxxxxx>
---
 drivers/iio/accel/Kconfig        |   4 ++
 drivers/iio/accel/adxl355.h      |   2 +-
 drivers/iio/accel/adxl355_core.c | 102 ++++++++++++++++++++++++++++++-
 drivers/iio/accel/adxl355_i2c.c  |   3 +-
 drivers/iio/accel/adxl355_spi.c  |   2 +-
 5 files changed, 108 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
index d0c45c809..9c16c1841 100644
--- a/drivers/iio/accel/Kconfig
+++ b/drivers/iio/accel/Kconfig
@@ -69,6 +69,8 @@ config ADXL355_I2C
 	depends on I2C
 	select ADXL355
 	select REGMAP_I2C
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
 	help
 	  Say Y here if you want to build i2c support for the Analog Devices
 	  ADXL355 3-axis digital accelerometer.
@@ -82,6 +84,8 @@ config ADXL355_SPI
 	depends on SPI
 	select ADXL355
 	select REGMAP_SPI
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
 	help
 	  Say Y here if you want to build spi support for the Analog Devices
 	  ADXL355 3-axis digital accelerometer.
diff --git a/drivers/iio/accel/adxl355.h b/drivers/iio/accel/adxl355.h
index 322b0abb8..f0a376e6d 100644
--- a/drivers/iio/accel/adxl355.h
+++ b/drivers/iio/accel/adxl355.h
@@ -15,5 +15,5 @@ extern const struct regmap_access_table adxl355_readable_regs_tbl;
 extern const struct regmap_access_table adxl355_writeable_regs_tbl;
 
 int adxl355_core_probe(struct device *dev, struct regmap *regmap,
-		       const char *name);
+		       const char *name, int irq);
 #endif /* _ADXL355_H_ */
diff --git a/drivers/iio/accel/adxl355_core.c b/drivers/iio/accel/adxl355_core.c
index 47fbb31bc..f9dc2a530 100644
--- a/drivers/iio/accel/adxl355_core.c
+++ b/drivers/iio/accel/adxl355_core.c
@@ -9,6 +9,10 @@
 
 #include <asm/unaligned.h>
 #include <linux/bitfield.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger_consumer.h>
 #include <linux/iio/iio.h>
 #include <linux/limits.h>
 #include <linux/math64.h>
@@ -172,6 +176,7 @@ static const struct adxl355_chan_info adxl355_chans[] = {
 };
 
 struct adxl355_data {
+	int irq;
 	struct regmap *regmap;
 	struct device *dev;
 	struct mutex lock; /* lock to protect op_mode */
@@ -181,6 +186,12 @@ struct adxl355_data {
 	int calibbias[3];
 	int adxl355_hpf_3db_table[7][2];
 	u8 transf_buf[3] ____cacheline_aligned;
+	struct iio_trigger      *dready_trig;
+	/* Ensure correct alignment of timestamp when present */
+	struct {
+		__be32 channels[3];
+		s64 ts;
+	} buffer ____cacheline_aligned;
 };
 
 static int adxl355_set_op_mode(struct adxl355_data *data,
@@ -499,12 +510,46 @@ static int adxl355_read_avail(struct iio_dev *indio_dev,
 	}
 }
 
+static const unsigned long adxl355_avail_scan_masks[] = {
+	GENMASK(3, 0),
+	0
+};
+
 static const struct iio_info adxl355_info = {
 	.read_raw	= adxl355_read_raw,
 	.write_raw	= adxl355_write_raw,
 	.read_avail	= &adxl355_read_avail
 };
 
+static const struct iio_trigger_ops adxl355_trigger_ops = {
+	.validate_device = &iio_trigger_validate_own_device,
+};
+
+static irqreturn_t adxl355_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct adxl355_data *data = iio_priv(indio_dev);
+	int ret;
+
+	mutex_lock(&data->lock);
+
+	ret = regmap_bulk_read(data->regmap, ADXL355_XDATA3_REG,
+			       data->buffer.channels,
+			       9);
+	if (ret)
+		goto out_unlock_notify;
+
+	iio_push_to_buffers_with_timestamp(indio_dev, &data->buffer,
+					   pf->timestamp);
+
+out_unlock_notify:
+	mutex_unlock(&data->lock);
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
 #define ADXL355_ACCEL_CHANNEL(index, reg, axis) {			\
 	.type = IIO_ACCEL,						\
 	.address = reg,							\
@@ -518,6 +563,7 @@ static const struct iio_info adxl355_info = {
 	.info_mask_shared_by_type_available =				\
 		BIT(IIO_CHAN_INFO_SAMP_FREQ) |				\
 		BIT(IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY),	\
+	.scan_index = index,						\
 	.scan_type = {							\
 		.sign = 's',						\
 		.realbits = 20,						\
@@ -537,17 +583,56 @@ static const struct iio_chan_spec adxl355_channels[] = {
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 				      BIT(IIO_CHAN_INFO_SCALE) |
 				      BIT(IIO_CHAN_INFO_OFFSET),
+		.scan_index = 3,
 		.scan_type = {
 			.sign = 's',
 			.realbits = 12,
 			.storagebits = 16,
 			.endianness = IIO_BE,
 		},
-	}
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(4)
 };
 
+static int adxl355_probe_trigger(struct iio_dev *indio_dev)
+{
+	struct adxl355_data *data = iio_priv(indio_dev);
+	int ret;
+
+	if (!data->irq) {
+		dev_info(data->dev, "no irq, using polling\n");
+		return 0;
+	}
+
+	data->dready_trig = devm_iio_trigger_alloc(data->dev, "%s-dev%d",
+						   indio_dev->name,
+						   indio_dev->id);
+	if (!data->dready_trig)
+		return -ENOMEM;
+
+	data->dready_trig->ops = &adxl355_trigger_ops;
+	iio_trigger_set_drvdata(data->dready_trig, indio_dev);
+
+	ret = devm_request_irq(data->dev, data->irq,
+			       &iio_trigger_generic_data_rdy_poll,
+			       IRQF_ONESHOT, "adxl355_irq", data->dready_trig);
+	if (ret < 0)
+		return dev_err_probe(data->dev, ret, "request irq %d failed\n",
+				     data->irq);
+
+	ret = devm_iio_trigger_register(data->dev, data->dready_trig);
+	if (ret) {
+		dev_err(data->dev, "iio trigger register failed\n");
+		return ret;
+	}
+
+	indio_dev->trig = iio_trigger_get(data->dready_trig);
+
+	return 0;
+}
+
 int adxl355_core_probe(struct device *dev, struct regmap *regmap,
-		       const char *name)
+		       const char *name, int irq)
 {
 	struct adxl355_data *data;
 	struct iio_dev *indio_dev;
@@ -560,6 +645,7 @@ int adxl355_core_probe(struct device *dev, struct regmap *regmap,
 	data = iio_priv(indio_dev);
 	data->regmap = regmap;
 	data->dev = dev;
+	data->irq = irq;
 	data->op_mode = ADXL355_STANDBY;
 	mutex_init(&data->lock);
 
@@ -568,6 +654,7 @@ int adxl355_core_probe(struct device *dev, struct regmap *regmap,
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->channels = adxl355_channels;
 	indio_dev->num_channels = ARRAY_SIZE(adxl355_channels);
+	indio_dev->available_scan_masks = adxl355_avail_scan_masks;
 
 	ret = adxl355_setup(data);
 	if (ret < 0) {
@@ -575,6 +662,17 @@ int adxl355_core_probe(struct device *dev, struct regmap *regmap,
 		return ret;
 	}
 
+	ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
+					      &iio_pollfunc_store_time,
+					      &adxl355_trigger_handler, NULL);
+	if (ret < 0)
+		return dev_err_probe(dev, ret,
+				     "iio triggered buffer setup failed\n");
+
+	ret = adxl355_probe_trigger(indio_dev);
+	if (ret < 0)
+		return ret;
+
 	return devm_iio_device_register(dev, indio_dev);
 }
 EXPORT_SYMBOL_GPL(adxl355_core_probe);
diff --git a/drivers/iio/accel/adxl355_i2c.c b/drivers/iio/accel/adxl355_i2c.c
index e3070ee81..c18521819 100644
--- a/drivers/iio/accel/adxl355_i2c.c
+++ b/drivers/iio/accel/adxl355_i2c.c
@@ -31,7 +31,8 @@ static int adxl355_i2c_probe(struct i2c_client *client)
 		return PTR_ERR(regmap);
 	}
 
-	return adxl355_core_probe(&client->dev, regmap, client->name);
+	return adxl355_core_probe(&client->dev, regmap, client->name,
+				  client->irq);
 }
 
 static const struct i2c_device_id adxl355_i2c_id[] = {
diff --git a/drivers/iio/accel/adxl355_spi.c b/drivers/iio/accel/adxl355_spi.c
index a16bd1407..f9ba153f6 100644
--- a/drivers/iio/accel/adxl355_spi.c
+++ b/drivers/iio/accel/adxl355_spi.c
@@ -34,7 +34,7 @@ static int adxl355_spi_probe(struct spi_device *spi)
 		return PTR_ERR(regmap);
 	}
 
-	return adxl355_core_probe(&spi->dev, regmap, id->name);
+	return adxl355_core_probe(&spi->dev, regmap, id->name, spi->irq);
 }
 
 static const struct spi_device_id adxl355_spi_id[] = {
-- 
2.30.1