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 <redacted>
---
 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 d1163cde1..45397dcce 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>

@@ -153,6 +157,7 @@ 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 */

@@ -162,6 +167,12 @@ 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,

@@ -493,12 +504,46 @@ 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,                                                 \

@@ -512,6 +557,7 @@ 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,                                         \

@@ -531,17 +577,56 @@ 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;

@@ -554,6 +639,7 @@ 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);

@@ -562,6 +648,7 @@ 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) {

@@ -569,6 +656,17 @@ 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