[PATCH 4/4] iio: accel: mma8452: Add single pulse/tap event detection feature for fxls8471.

[Harinath Nampally <harinath922@gmail.com>]

This patch adds following changes to support tap feature:
- defines pulse event related registers
- enables and handles single pulse interrupt for fxls8471
- handles IIO_EV_DIR_EITHER in read/write callbacks
  because event direction for pulse is either rising or
  falling.
- configures read/write event value for pulse latency register
  using IIO_EV_INFO_HYSTERESIS.
- add multiple events like pulse and tranient event spec
  as elements of event_spec array named 'mma8452_accel_events'

Except mma8653 chip all other chips like mma845x and
fxls8471 have single tap detection feature.
Tested thoroughly using iio_event_monitor application on
imx6ul-evk board.

Signed-off-by: Harinath Nampally <harinath922@gmail.com>
---
 drivers/iio/accel/mma8452.c | 156 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 151 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
index 43c3a6b..36f1b56 100644
--- a/drivers/iio/accel/mma8452.c
+++ b/drivers/iio/accel/mma8452.c
@@ -72,6 +72,19 @@
 #define  MMA8452_TRANSIENT_THS_MASK		GENMASK(6, 0)
 #define MMA8452_TRANSIENT_COUNT			0x20
 #define MMA8452_TRANSIENT_CHAN_SHIFT 1
+#define MMA8452_PULSE_CFG			0x21
+#define MMA8452_PULSE_CFG_CHAN(chan)		BIT(chan * 2)
+#define MMA8452_PULSE_CFG_ELE			BIT(6)
+#define MMA8452_PULSE_SRC			0x22
+#define MMA8452_PULSE_SRC_XPULSE		BIT(4)
+#define MMA8452_PULSE_SRC_YPULSE		BIT(5)
+#define MMA8452_PULSE_SRC_ZPULSE		BIT(6)
+#define MMA8452_PULSE_THS			0x23
+#define MMA8452_PULSE_THS_MASK			GENMASK(6, 0)
+#define MMA8452_PULSE_COUNT			0x26
+#define MMA8452_PULSE_CHAN_SHIFT		2
+#define MMA8452_PULSE_LTCY			0x27
+
 #define MMA8452_CTRL_REG1			0x2a
 #define  MMA8452_CTRL_ACTIVE			BIT(0)
 #define  MMA8452_CTRL_DR_MASK			GENMASK(5, 3)
@@ -91,6 +104,7 @@
 
 #define  MMA8452_INT_DRDY			BIT(0)
 #define  MMA8452_INT_FF_MT			BIT(2)
+#define  MMA8452_INT_PULSE			BIT(3)
 #define  MMA8452_INT_TRANS			BIT(5)
 
 #define MMA8451_DEVICE_ID			0x1a
@@ -155,6 +169,16 @@ static const struct mma8452_event_regs trans_ev_regs = {
 		.ev_count = MMA8452_TRANSIENT_COUNT,
 };
 
+static const struct mma8452_event_regs pulse_ev_regs = {
+		.ev_cfg = MMA8452_PULSE_CFG,
+		.ev_cfg_ele = MMA8452_PULSE_CFG_ELE,
+		.ev_cfg_chan_shift = MMA8452_PULSE_CHAN_SHIFT,
+		.ev_src = MMA8452_PULSE_SRC,
+		.ev_ths = MMA8452_PULSE_THS,
+		.ev_ths_mask = MMA8452_PULSE_THS_MASK,
+		.ev_count = MMA8452_PULSE_COUNT,
+};
+
 /**
  * struct mma_chip_info - chip specific data
  * @chip_id:			WHO_AM_I register's value
@@ -784,6 +808,14 @@ static int mma8452_get_event_regs(struct mma8452_data *data,
 		case IIO_EV_DIR_FALLING:
 			*ev_reg = &ff_mt_ev_regs;
 			return 0;
+		case IIO_EV_DIR_EITHER:
+			if (!(data->chip_info->all_events
+					& MMA8452_INT_PULSE) ||
+				!(data->chip_info->enabled_events
+					& MMA8452_INT_PULSE))
+				return -EINVAL;
+			*ev_reg = &pulse_ev_regs;
+			return 0;
 		default:
 			return -EINVAL;
 		}
@@ -848,6 +880,25 @@ static int mma8452_read_event_value(struct iio_dev *indio_dev,
 				return ret;
 		}
 
+	case IIO_EV_INFO_HYSTERESIS:
+		if (!(data->chip_info->all_events & MMA8452_INT_PULSE) ||
+			!(data->chip_info->enabled_events & MMA8452_INT_PULSE))
+			return -EINVAL;
+
+		ret = i2c_smbus_read_byte_data(data->client,
+						MMA8452_PULSE_LTCY);
+		if (ret < 0)
+			return ret;
+
+		power_mode = mma8452_get_power_mode(data);
+		if (power_mode < 0)
+			return power_mode;
+
+		us = ret * mma8452_time_step_us[power_mode][
+				mma8452_get_odr_index(data)];
+		*val = us / USEC_PER_SEC;
+		*val2 = us % USEC_PER_SEC;
+
 		return IIO_VAL_INT_PLUS_MICRO;
 
 	default:
@@ -908,6 +959,24 @@ static int mma8452_write_event_value(struct iio_dev *indio_dev,
 
 		return mma8452_change_config(data, MMA8452_TRANSIENT_CFG, reg);
 
+	case IIO_EV_INFO_HYSTERESIS:
+		if (!(data->chip_info->all_events & MMA8452_INT_PULSE) ||
+			!(data->chip_info->enabled_events & MMA8452_INT_PULSE))
+			return -EINVAL;
+
+		ret = mma8452_get_power_mode(data);
+		if (ret < 0)
+			return ret;
+
+		steps = (val * USEC_PER_SEC + val2) /
+				mma8452_time_step_us[ret][
+					mma8452_get_odr_index(data)];
+
+		if (steps < 0 || steps > 0xff)
+			return -EINVAL;
+
+		return mma8452_change_config(data, MMA8452_PULSE_LTCY, steps);
+
 	default:
 		return -EINVAL;
 	}
@@ -937,6 +1006,14 @@ static int mma8452_read_event_config(struct iio_dev *indio_dev,
 
 		return !!(ret & BIT(chan->scan_index +
 				ev_regs->ev_cfg_chan_shift));
+	case IIO_EV_DIR_EITHER:
+		ret = i2c_smbus_read_byte_data(data->client,
+				ev_regs->ev_cfg);
+		if (ret < 0)
+			return ret;
+
+		return !!(ret & BIT(chan->scan_index *
+				ev_regs->ev_cfg_chan_shift));
 	default:
 		return -EINVAL;
 	}
@@ -988,6 +1065,25 @@ static int mma8452_write_event_config(struct iio_dev *indio_dev,
 		val |= ev_regs->ev_cfg_ele;
 
 		return mma8452_change_config(data, ev_regs->ev_cfg, val);
+
+	case IIO_EV_DIR_EITHER:
+		val = i2c_smbus_read_byte_data(data->client, ev_regs->ev_cfg);
+		if (val < 0)
+			return val;
+
+		if (state) {
+			val &= ~BIT(chan->scan_index *
+					ev_regs->ev_cfg_chan_shift);
+			val |= BIT(chan->scan_index *
+					ev_regs->ev_cfg_chan_shift);
+		} else {
+			val &= ~BIT(chan->scan_index *
+					ev_regs->ev_cfg_chan_shift);
+		}
+
+		val |= ev_regs->ev_cfg_ele;
+
+		return mma8452_change_config(data, ev_regs->ev_cfg, val);
 	default:
 		return -EINVAL;
 	}
@@ -1025,6 +1121,38 @@ static void mma8452_transient_interrupt(struct iio_dev *indio_dev)
 			       ts);
 }
 
+static void mma8452_pulse_interrupt(struct iio_dev *indio_dev)
+{
+	struct mma8452_data *data = iio_priv(indio_dev);
+	s64 ts = iio_get_time_ns(indio_dev);
+	int src;
+
+	src = i2c_smbus_read_byte_data(data->client, MMA8452_PULSE_SRC);
+	if (src < 0)
+		return;
+
+	if (src & MMA8452_PULSE_SRC_XPULSE)
+		iio_push_event(indio_dev,
+			       IIO_MOD_EVENT_CODE(IIO_ACCEL, 0, IIO_MOD_X,
+						  IIO_EV_TYPE_MAG,
+						  IIO_EV_DIR_EITHER),
+			       ts);
+
+	if (src & MMA8452_PULSE_SRC_YPULSE)
+		iio_push_event(indio_dev,
+			       IIO_MOD_EVENT_CODE(IIO_ACCEL, 0, IIO_MOD_Y,
+						  IIO_EV_TYPE_MAG,
+						  IIO_EV_DIR_EITHER),
+			       ts);
+
+	if (src & MMA8452_PULSE_SRC_ZPULSE)
+		iio_push_event(indio_dev,
+			       IIO_MOD_EVENT_CODE(IIO_ACCEL, 0, IIO_MOD_Z,
+						  IIO_EV_TYPE_MAG,
+						  IIO_EV_DIR_EITHER),
+			       ts);
+}
+
 static irqreturn_t mma8452_interrupt(int irq, void *p)
 {
 	struct iio_dev *indio_dev = p;
@@ -1063,6 +1191,11 @@ static irqreturn_t mma8452_interrupt(int irq, void *p)
 		ret = IRQ_HANDLED;
 	}
 
+	if (src & MMA8452_INT_PULSE) {
+		mma8452_pulse_interrupt(indio_dev);
+		ret = IRQ_HANDLED;
+	}
+
 	return ret;
 }
 
@@ -1130,8 +1263,10 @@ static const struct iio_event_spec mma8652_freefall_event[] = {
 	},
 };
 
-static const struct iio_event_spec mma8452_transient_event[] = {
+
+static const struct iio_event_spec mma8452_accel_events[] = {
 	{
+		//trasient event
 		.type = IIO_EV_TYPE_MAG,
 		.dir = IIO_EV_DIR_RISING,
 		.mask_separate = BIT(IIO_EV_INFO_ENABLE),
@@ -1139,6 +1274,15 @@ static const struct iio_event_spec mma8452_transient_event[] = {
 					BIT(IIO_EV_INFO_PERIOD) |
 					BIT(IIO_EV_INFO_HIGH_PASS_FILTER_3DB)
 	},
+	{
+		//pulse event
+		.type = IIO_EV_TYPE_MAG,
+		.dir = IIO_EV_DIR_EITHER,
+		.mask_separate = BIT(IIO_EV_INFO_ENABLE),
+		.mask_shared_by_type = BIT(IIO_EV_INFO_VALUE) |
+					BIT(IIO_EV_INFO_PERIOD) |
+					BIT(IIO_EV_INFO_HYSTERESIS)
+	},
 };
 
 static const struct iio_event_spec mma8452_motion_event[] = {
@@ -1202,8 +1346,8 @@ static struct attribute_group mma8452_event_attribute_group = {
 		.shift = 16 - (bits), \
 		.endianness = IIO_BE, \
 	}, \
-	.event_spec = mma8452_transient_event, \
-	.num_event_specs = ARRAY_SIZE(mma8452_transient_event), \
+	.event_spec = mma8452_accel_events, \
+	.num_event_specs = ARRAY_SIZE(mma8452_accel_events), \
 }
 
 #define MMA8652_CHANNEL(axis, idx, bits) { \
@@ -1368,9 +1512,11 @@ static const struct mma_chip_info mma_chip_info_table[] = {
 		 */
 		.all_events = MMA8452_INT_DRDY |
 					MMA8452_INT_TRANS |
-					MMA8452_INT_FF_MT,
+					MMA8452_INT_FF_MT |
+					MMA8452_INT_PULSE,
 		.enabled_events = MMA8452_INT_TRANS |
-					MMA8452_INT_FF_MT,
+					MMA8452_INT_FF_MT |
+					MMA8452_INT_PULSE,
 	},
 };
 
-- 
2.7.4