This patch adds support for buffered readings for the 3-axis
accelerometer mxc4005.

Signed-off-by: Teodora Baluta <teodora.bal...@intel.com>
---
 drivers/iio/accel/Kconfig   |  2 ++
 drivers/iio/accel/mxc4005.c | 75 ++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 73 insertions(+), 4 deletions(-)

diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
index 7f534a3..e8d135e 100644
--- a/drivers/iio/accel/Kconfig
+++ b/drivers/iio/accel/Kconfig
@@ -140,6 +140,8 @@ config MMA9553
 config MXC4005
        tristate "Memsic MXC4005XC 3-Axis Accelerometer Driver"
        depends on I2C
+       select IIO_BUFFER
+       select IIO_TRIGGERED_BUFFER
        select REGMAP_I2C
        help
          Say yes here to build support for the Memsic MXC4005XC 3-axis
diff --git a/drivers/iio/accel/mxc4005.c b/drivers/iio/accel/mxc4005.c
index 0f0410c..114c14d 100644
--- a/drivers/iio/accel/mxc4005.c
+++ b/drivers/iio/accel/mxc4005.c
@@ -19,6 +19,9 @@
 #include <linux/acpi.h>
 #include <linux/regmap.h>
 #include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger_consumer.h>
 
 #define MXC4005_DRV_NAME               "mxc4005"
 #define MXC4005_REGMAP_NAME            "mxc4005_regmap"
@@ -54,6 +57,7 @@ struct mxc4005_data {
        struct i2c_client *client;
        struct mutex mutex;
        struct regmap *regmap;
+       s16 buffer[8];
 };
 
 /*
@@ -125,6 +129,20 @@ static const struct regmap_config mxc4005_regmap_config = {
        .writeable_reg = mxc4005_is_writeable_reg,
 };
 
+static int mxc4005_read_xyz(struct mxc4005_data *data)
+{
+       int ret;
+
+       ret = regmap_bulk_read(data->regmap, MXC4005_REG_XOUT_UPPER,
+                              (u8 *) data->buffer, sizeof(data->buffer));
+       if (ret < 0) {
+               dev_err(&data->client->dev, "failed to read axes\n");
+               return ret;
+       }
+
+       return 0;
+}
+
 static int mxc4005_read_axis(struct mxc4005_data *data,
                             int axis)
 {
@@ -190,6 +208,7 @@ static int mxc4005_read_raw(struct iio_dev *indio_dev,
                            int *val, int *val2, long mask)
 {
        struct mxc4005_data *data = iio_priv(indio_dev);
+       int axis = chan->scan_index;
        int ret;
 
        switch (mask) {
@@ -200,12 +219,13 @@ static int mxc4005_read_raw(struct iio_dev *indio_dev,
                                return -EBUSY;
 
                        mutex_lock(&data->mutex);
-                       ret = mxc4005_read_axis(data, chan->address);
+                       ret = mxc4005_read_axis(data, axis);
                        mutex_unlock(&data->mutex);
                        if (ret < 0)
                                return ret;
                        ret = be16_to_cpu(ret);
-                       *val = sign_extend32(ret >> 4, 11);
+                       *val = sign_extend32(ret >> chan->scan_type.shift,
+                                            chan->scan_type.realbits - 1);
                        return IIO_VAL_INT;
                default:
                        return -EINVAL;
@@ -259,17 +279,47 @@ static const struct iio_info mxc4005_info = {
        .type = IIO_ACCEL,                                      \
        .modified = 1,                                          \
        .channel2 = IIO_MOD_##_axis,                            \
-       .address = AXIS_##_axis,                                \
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),           \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),   \
+       .scan_index = AXIS_##_axis,                             \
+       .scan_type = {                                          \
+               .sign = 's',                                    \
+               .realbits = 12,                                 \
+               .storagebits = 16,                              \
+               .shift = 4,                                     \
+               .endianness = IIO_BE,                           \
+       },                                                      \
 }
 
 static const struct iio_chan_spec mxc4005_channels[] = {
        MXC4005_CHANNEL(X),
        MXC4005_CHANNEL(Y),
        MXC4005_CHANNEL(Z),
+       IIO_CHAN_SOFT_TIMESTAMP(3),
 };
 
+static irqreturn_t mxc4005_trigger_handler(int irq, void *private)
+{
+       struct iio_poll_func *pf = private;
+       struct iio_dev *indio_dev = pf->indio_dev;
+       struct mxc4005_data *data = iio_priv(indio_dev);
+       int ret;
+
+       mutex_lock(&data->mutex);
+       ret = mxc4005_read_xyz(data);
+       mutex_unlock(&data->mutex);
+       if (ret < 0)
+               goto err;
+
+       iio_push_to_buffers_with_timestamp(indio_dev, data->buffer,
+                                          iio_get_time_ns());
+
+err:
+       iio_trigger_notify_done(indio_dev->trig);
+
+       return IRQ_HANDLED;
+}
+
 static int mxc4005_chip_init(struct mxc4005_data *data)
 {
        int ret;
@@ -324,14 +374,29 @@ static int mxc4005_probe(struct i2c_client *client,
        indio_dev->modes = INDIO_DIRECT_MODE;
        indio_dev->info = &mxc4005_info;
 
+       ret = iio_triggered_buffer_setup(indio_dev,
+                                        &iio_pollfunc_store_time,
+                                        mxc4005_trigger_handler,
+                                        NULL);
+       if (ret < 0) {
+               dev_err(&client->dev,
+                       "failed to setup iio triggered buffer\n");
+               return ret;
+       }
+
        ret = iio_device_register(indio_dev);
        if (ret < 0) {
                dev_err(&client->dev,
                        "unable to register iio device %d\n", ret);
-               return ret;
+               goto err_buffer_cleanup;
        }
 
        return 0;
+
+err_buffer_cleanup:
+       iio_triggered_buffer_cleanup(indio_dev);
+
+       return ret;
 }
 
 static int mxc4005_remove(struct i2c_client *client)
@@ -340,6 +405,8 @@ static int mxc4005_remove(struct i2c_client *client)
 
        iio_device_unregister(indio_dev);
 
+       iio_triggered_buffer_cleanup(indio_dev);
+
        return 0;
 }
 
-- 
1.9.1

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