iio: accel: bma400: Add step change event

Added support for event when there is a detection of step change.
INT1 pin is used to interrupt and event is pushed to userspace.
Signed-off-by: Jagath Jog J <jagathjog1996@gmail.com>
Link: https://lore.kernel.org/r/20220505133021.22362-7-jagathjog1996@gmail.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/accel/bma400.h

@@ -39,6 +39,7 @@
 #define BMA400_INT_STAT0_REG        0x0e
 #define BMA400_INT_STAT1_REG        0x0f
 #define BMA400_INT_STAT2_REG        0x10
+#define BMA400_INT12_MAP_REG        0x23
 
 /* Temperature register */
 #define BMA400_TEMP_DATA_REG        0x11
@@ -55,6 +56,7 @@
 #define BMA400_STEP_STAT_REG        0x18
 #define BMA400_STEP_INT_MSK         BIT(0)
 #define BMA400_STEP_RAW_LEN         0x03
+#define BMA400_STEP_STAT_MASK       GENMASK(9, 8)
 
 /*
  * Read-write configuration registers

drivers/iio/accel/bma400_core.c

@@ -25,6 +25,7 @@
 
 #include <linux/iio/iio.h>
 #include <linux/iio/buffer.h>
+#include <linux/iio/events.h>
 #include <linux/iio/trigger.h>
 #include <linux/iio/trigger_consumer.h>
 #include <linux/iio/triggered_buffer.h>
@@ -78,6 +79,7 @@ struct bma400_data {
 	int scale;
 	struct iio_trigger *trig;
 	int steps_enabled;
+	bool step_event_en;
 	/* Correct time stamp alignment */
 	struct {
 		__le16 buff[3];
@@ -176,6 +178,12 @@ static const struct iio_chan_spec_ext_info bma400_ext_info[] = {
 	{ }
 };
 
+static const struct iio_event_spec bma400_step_detect_event = {
+	.type = IIO_EV_TYPE_CHANGE,
+	.dir = IIO_EV_DIR_NONE,
+	.mask_separate = BIT(IIO_EV_INFO_ENABLE),
+};
+
 #define BMA400_ACC_CHANNEL(_index, _axis) { \
 	.type = IIO_ACCEL, \
 	.modified = 1, \
@@ -218,6 +226,8 @@ static const struct iio_chan_spec bma400_channels[] = {
 		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
 				      BIT(IIO_CHAN_INFO_ENABLE),
 		.scan_index = -1, /* No buffer support */
+		.event_spec = &bma400_step_detect_event,
+		.num_event_specs = 1,
 	},
 	IIO_CHAN_SOFT_TIMESTAMP(4),
 };
@@ -907,6 +917,58 @@ static int bma400_write_raw_get_fmt(struct iio_dev *indio_dev,
 	}
 }
 
+static int bma400_read_event_config(struct iio_dev *indio_dev,
+				    const struct iio_chan_spec *chan,
+				    enum iio_event_type type,
+				    enum iio_event_direction dir)
+{
+	struct bma400_data *data = iio_priv(indio_dev);
+
+	switch (chan->type) {
+	case IIO_STEPS:
+		return data->step_event_en;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int bma400_steps_event_enable(struct bma400_data *data, int state)
+{
+	int ret;
+
+	ret = bma400_enable_steps(data, 1);
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(data->regmap, BMA400_INT12_MAP_REG,
+				 BMA400_STEP_INT_MSK,
+				 FIELD_PREP(BMA400_STEP_INT_MSK,
+					    state));
+	if (ret)
+		return ret;
+	data->step_event_en = state;
+	return 0;
+}
+
+static int bma400_write_event_config(struct iio_dev *indio_dev,
+				     const struct iio_chan_spec *chan,
+				     enum iio_event_type type,
+				     enum iio_event_direction dir, int state)
+{
+	struct bma400_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (chan->type) {
+	case IIO_STEPS:
+		mutex_lock(&data->mutex);
+		ret = bma400_steps_event_enable(data, state);
+		mutex_unlock(&data->mutex);
+		return ret;
+	default:
+		return -EINVAL;
+	}
+}
+
 static int bma400_data_rdy_trigger_set_state(struct iio_trigger *trig,
 					     bool state)
 {
@@ -937,6 +999,8 @@ static const struct iio_info bma400_info = {
 	.read_avail        = bma400_read_avail,
 	.write_raw         = bma400_write_raw,
 	.write_raw_get_fmt = bma400_write_raw_get_fmt,
+	.read_event_config = bma400_read_event_config,
+	.write_event_config = bma400_write_event_config,
 };
 
 static const struct iio_trigger_ops bma400_trigger_ops = {
@@ -984,6 +1048,7 @@ static irqreturn_t bma400_interrupt(int irq, void *private)
 {
 	struct iio_dev *indio_dev = private;
 	struct bma400_data *data = iio_priv(indio_dev);
+	s64 timestamp = iio_get_time_ns(indio_dev);
 	int ret;
 
 	/* Lock to protect the data->status */
@@ -998,12 +1063,23 @@ static irqreturn_t bma400_interrupt(int irq, void *private)
 	if (ret || !data->status)
 		goto unlock_err;
 
+	if (FIELD_GET(BMA400_STEP_STAT_MASK, le16_to_cpu(data->status))) {
+		iio_push_event(indio_dev,
+			       IIO_MOD_EVENT_CODE(IIO_STEPS, 0, IIO_NO_MOD,
+						  IIO_EV_TYPE_CHANGE,
+						  IIO_EV_DIR_NONE),
+			       timestamp);
+	}
+
 	if (FIELD_GET(BMA400_INT_DRDY_MSK, le16_to_cpu(data->status))) {
 		mutex_unlock(&data->mutex);
 		iio_trigger_poll_chained(data->trig);
 		return IRQ_HANDLED;
 	}
 
+	mutex_unlock(&data->mutex);
+	return IRQ_HANDLED;
+
 unlock_err:
 	mutex_unlock(&data->mutex);
 	return IRQ_NONE;