iio:accel:mma8452: check values to be written
[platform/kernel/linux-starfive.git] / drivers / iio / accel / mma8452.c
index 5b80657..42640b1 100644 (file)
@@ -9,29 +9,50 @@
  *
  * 7-bit I2C slave address 0x1c/0x1d (pin selectable)
  *
- * TODO: interrupt, thresholding, orientation / freefall events, autosleep
+ * TODO: orientation / freefall events, autosleep
  */
 
 #include <linux/module.h>
 #include <linux/i2c.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
-#include <linux/iio/trigger_consumer.h>
 #include <linux/iio/buffer.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
 #include <linux/iio/triggered_buffer.h>
+#include <linux/iio/events.h>
 #include <linux/delay.h>
 
 #define MMA8452_STATUS 0x00
 #define MMA8452_OUT_X 0x01 /* MSB first, 12-bit  */
 #define MMA8452_OUT_Y 0x03
 #define MMA8452_OUT_Z 0x05
+#define MMA8452_INT_SRC 0x0c
 #define MMA8452_WHO_AM_I 0x0d
 #define MMA8452_DATA_CFG 0x0e
+#define MMA8452_HP_FILTER_CUTOFF 0x0f
+#define MMA8452_HP_FILTER_CUTOFF_SEL_MASK      (BIT(0) | BIT(1))
+#define MMA8452_TRANSIENT_CFG 0x1d
+#define MMA8452_TRANSIENT_CFG_ELE              BIT(4)
+#define MMA8452_TRANSIENT_CFG_CHAN(chan)       BIT(chan + 1)
+#define MMA8452_TRANSIENT_CFG_HPF_BYP          BIT(0)
+#define MMA8452_TRANSIENT_SRC 0x1e
+#define MMA8452_TRANSIENT_SRC_XTRANSE          BIT(1)
+#define MMA8452_TRANSIENT_SRC_YTRANSE          BIT(3)
+#define MMA8452_TRANSIENT_SRC_ZTRANSE          BIT(5)
+#define MMA8452_TRANSIENT_THS 0x1f
+#define MMA8452_TRANSIENT_THS_MASK     0x7f
+#define MMA8452_TRANSIENT_COUNT 0x20
 #define MMA8452_OFF_X 0x2f
 #define MMA8452_OFF_Y 0x30
 #define MMA8452_OFF_Z 0x31
 #define MMA8452_CTRL_REG1 0x2a
 #define MMA8452_CTRL_REG2 0x2b
+#define MMA8452_CTRL_REG2_RST          BIT(6)
+#define MMA8452_CTRL_REG4 0x2d
+#define MMA8452_CTRL_REG5 0x2e
+
+#define MMA8452_MAX_REG 0x31
 
 #define MMA8452_STATUS_DRDY (BIT(2) | BIT(1) | BIT(0))
 
 #define MMA8452_DATA_CFG_FS_2G 0
 #define MMA8452_DATA_CFG_FS_4G 1
 #define MMA8452_DATA_CFG_FS_8G 2
+#define MMA8452_DATA_CFG_HPF_MASK BIT(4)
+
+#define MMA8452_INT_DRDY       BIT(0)
+#define MMA8452_INT_TRANS      BIT(5)
 
 #define MMA8452_DEVICE_ID 0x2a
 
@@ -106,6 +131,12 @@ static int mma8452_get_int_plus_micros_index(const int (*vals)[2], int n,
        return -EINVAL;
 }
 
+static int mma8452_get_odr_index(struct mma8452_data *data)
+{
+       return (data->ctrl_reg1 & MMA8452_CTRL_DR_MASK) >>
+                       MMA8452_CTRL_DR_SHIFT;
+}
+
 static const int mma8452_samp_freq[8][2] = {
        {800, 0}, {400, 0}, {200, 0}, {100, 0}, {50, 0}, {12, 500000},
        {6, 250000}, {1, 560000}
@@ -121,6 +152,30 @@ static const int mma8452_scales[3][2] = {
        {0, 9577}, {0, 19154}, {0, 38307}
 };
 
+/* Datasheet table 35  (step time vs sample frequency) */
+static const int mma8452_transient_time_step_us[8] = {
+       1250,
+       2500,
+       5000,
+       10000,
+       20000,
+       20000,
+       20000,
+       20000
+};
+
+/* Datasheet table 18 (normal mode) */
+static const int mma8452_hp_filter_cutoff[8][4][2] = {
+       { {16, 0}, {8, 0}, {4, 0}, {2, 0} },            /* 800 Hz sample */
+       { {16, 0}, {8, 0}, {4, 0}, {2, 0} },            /* 400 Hz sample */
+       { {8, 0}, {4, 0}, {2, 0}, {1, 0} },             /* 200 Hz sample */
+       { {4, 0}, {2, 0}, {1, 0}, {0, 500000} },        /* 100 Hz sample */
+       { {2, 0}, {1, 0}, {0, 500000}, {0, 250000} },   /* 50 Hz sample */
+       { {2, 0}, {1, 0}, {0, 500000}, {0, 250000} },   /* 12.5 Hz sample */
+       { {2, 0}, {1, 0}, {0, 500000}, {0, 250000} },   /* 6.25 Hz sample */
+       { {2, 0}, {1, 0}, {0, 500000}, {0, 250000} }    /* 1.56 Hz sample */
+};
+
 static ssize_t mma8452_show_samp_freq_avail(struct device *dev,
                                struct device_attribute *attr, char *buf)
 {
@@ -135,9 +190,23 @@ static ssize_t mma8452_show_scale_avail(struct device *dev,
                ARRAY_SIZE(mma8452_scales));
 }
 
+static ssize_t mma8452_show_hp_cutoff_avail(struct device *dev,
+                                           struct device_attribute *attr,
+                                           char *buf)
+{
+       struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+       struct mma8452_data *data = iio_priv(indio_dev);
+       int i = mma8452_get_odr_index(data);
+
+       return mma8452_show_int_plus_micros(buf, mma8452_hp_filter_cutoff[i],
+               ARRAY_SIZE(mma8452_hp_filter_cutoff[0]));
+}
+
 static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(mma8452_show_samp_freq_avail);
 static IIO_DEVICE_ATTR(in_accel_scale_available, S_IRUGO,
        mma8452_show_scale_avail, NULL, 0);
+static IIO_DEVICE_ATTR(in_accel_filter_high_pass_3db_frequency_available,
+                       S_IRUGO, mma8452_show_hp_cutoff_avail, NULL, 0);
 
 static int mma8452_get_samp_freq_index(struct mma8452_data *data,
        int val, int val2)
@@ -153,6 +222,31 @@ static int mma8452_get_scale_index(struct mma8452_data *data,
                ARRAY_SIZE(mma8452_scales), val, val2);
 }
 
+static int mma8452_get_hp_filter_index(struct mma8452_data *data,
+                                      int val, int val2)
+{
+       int i = mma8452_get_odr_index(data);
+
+       return mma8452_get_int_plus_micros_index(mma8452_hp_filter_cutoff[i],
+               ARRAY_SIZE(mma8452_hp_filter_cutoff[0]), val, val2);
+}
+
+static int mma8452_read_hp_filter(struct mma8452_data *data, int *hz, int *uHz)
+{
+       int i, ret;
+
+       ret = i2c_smbus_read_byte_data(data->client, MMA8452_HP_FILTER_CUTOFF);
+       if (ret < 0)
+               return ret;
+
+       i = mma8452_get_odr_index(data);
+       ret &= MMA8452_HP_FILTER_CUTOFF_SEL_MASK;
+       *hz = mma8452_hp_filter_cutoff[i][ret][0];
+       *uHz = mma8452_hp_filter_cutoff[i][ret][1];
+
+       return 0;
+}
+
 static int mma8452_read_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *chan,
                            int *val, int *val2, long mask)
@@ -180,8 +274,7 @@ static int mma8452_read_raw(struct iio_dev *indio_dev,
                *val2 = mma8452_scales[i][1];
                return IIO_VAL_INT_PLUS_MICRO;
        case IIO_CHAN_INFO_SAMP_FREQ:
-               i = (data->ctrl_reg1 & MMA8452_CTRL_DR_MASK) >>
-                       MMA8452_CTRL_DR_SHIFT;
+               i = mma8452_get_odr_index(data);
                *val = mma8452_samp_freq[i][0];
                *val2 = mma8452_samp_freq[i][1];
                return IIO_VAL_INT_PLUS_MICRO;
@@ -192,6 +285,16 @@ static int mma8452_read_raw(struct iio_dev *indio_dev,
                        return ret;
                *val = sign_extend32(ret, 7);
                return IIO_VAL_INT;
+       case IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY:
+               if (data->data_cfg & MMA8452_DATA_CFG_HPF_MASK) {
+                       ret = mma8452_read_hp_filter(data, val, val2);
+                       if (ret < 0)
+                               return ret;
+               } else {
+                       *val = 0;
+                       *val2 = 0;
+               }
+               return IIO_VAL_INT_PLUS_MICRO;
        }
        return -EINVAL;
 }
@@ -233,12 +336,31 @@ fail:
        return ret;
 }
 
+static int mma8452_set_hp_filter_frequency(struct mma8452_data *data,
+                                          int val, int val2)
+{
+       int i, reg;
+
+       i = mma8452_get_hp_filter_index(data, val, val2);
+       if (i < 0)
+               return i;
+
+       reg = i2c_smbus_read_byte_data(data->client,
+                                      MMA8452_HP_FILTER_CUTOFF);
+       if (reg < 0)
+               return reg;
+       reg &= ~MMA8452_HP_FILTER_CUTOFF_SEL_MASK;
+       reg |= i;
+
+       return mma8452_change_config(data, MMA8452_HP_FILTER_CUTOFF, reg);
+}
+
 static int mma8452_write_raw(struct iio_dev *indio_dev,
                             struct iio_chan_spec const *chan,
                             int val, int val2, long mask)
 {
        struct mma8452_data *data = iio_priv(indio_dev);
-       int i;
+       int i, ret;
 
        if (iio_buffer_enabled(indio_dev))
                return -EBUSY;
@@ -247,7 +369,7 @@ static int mma8452_write_raw(struct iio_dev *indio_dev,
        case IIO_CHAN_INFO_SAMP_FREQ:
                i = mma8452_get_samp_freq_index(data, val, val2);
                if (i < 0)
-                       return -EINVAL;
+                       return i;
 
                data->ctrl_reg1 &= ~MMA8452_CTRL_DR_MASK;
                data->ctrl_reg1 |= i << MMA8452_CTRL_DR_SHIFT;
@@ -256,7 +378,7 @@ static int mma8452_write_raw(struct iio_dev *indio_dev,
        case IIO_CHAN_INFO_SCALE:
                i = mma8452_get_scale_index(data, val, val2);
                if (i < 0)
-                       return -EINVAL;
+                       return i;
                data->data_cfg &= ~MMA8452_DATA_CFG_FS_MASK;
                data->data_cfg |= i;
                return mma8452_change_config(data, MMA8452_DATA_CFG,
@@ -266,11 +388,219 @@ static int mma8452_write_raw(struct iio_dev *indio_dev,
                        return -EINVAL;
                return mma8452_change_config(data, MMA8452_OFF_X +
                        chan->scan_index, val);
+
+       case IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY:
+               if (val == 0 && val2 == 0) {
+                       data->data_cfg &= ~MMA8452_DATA_CFG_HPF_MASK;
+               } else {
+                       data->data_cfg |= MMA8452_DATA_CFG_HPF_MASK;
+                       ret = mma8452_set_hp_filter_frequency(data, val, val2);
+                       if (ret < 0)
+                               return ret;
+               }
+               return mma8452_change_config(data, MMA8452_DATA_CFG,
+                                               data->data_cfg);
+
+       default:
+               return -EINVAL;
+       }
+}
+
+static int mma8452_read_thresh(struct iio_dev *indio_dev,
+                              const struct iio_chan_spec *chan,
+                              enum iio_event_type type,
+                              enum iio_event_direction dir,
+                              enum iio_event_info info,
+                              int *val, int *val2)
+{
+       struct mma8452_data *data = iio_priv(indio_dev);
+       int ret, us;
+
+       switch (info) {
+       case IIO_EV_INFO_VALUE:
+               ret = i2c_smbus_read_byte_data(data->client,
+                                              MMA8452_TRANSIENT_THS);
+               if (ret < 0)
+                       return ret;
+
+               *val = ret & MMA8452_TRANSIENT_THS_MASK;
+               return IIO_VAL_INT;
+
+       case IIO_EV_INFO_PERIOD:
+               ret = i2c_smbus_read_byte_data(data->client,
+                                              MMA8452_TRANSIENT_COUNT);
+               if (ret < 0)
+                       return ret;
+
+               us = ret * mma8452_transient_time_step_us[
+                               mma8452_get_odr_index(data)];
+               *val = us / USEC_PER_SEC;
+               *val2 = us % USEC_PER_SEC;
+               return IIO_VAL_INT_PLUS_MICRO;
+
+       case IIO_EV_INFO_HIGH_PASS_FILTER_3DB:
+               ret = i2c_smbus_read_byte_data(data->client,
+                                              MMA8452_TRANSIENT_CFG);
+               if (ret < 0)
+                       return ret;
+
+               if (ret & MMA8452_TRANSIENT_CFG_HPF_BYP) {
+                       *val = 0;
+                       *val2 = 0;
+               } else {
+                       ret = mma8452_read_hp_filter(data, val, val2);
+                       if (ret < 0)
+                               return ret;
+               }
+               return IIO_VAL_INT_PLUS_MICRO;
+
        default:
                return -EINVAL;
        }
 }
 
+static int mma8452_write_thresh(struct iio_dev *indio_dev,
+                               const struct iio_chan_spec *chan,
+                               enum iio_event_type type,
+                               enum iio_event_direction dir,
+                               enum iio_event_info info,
+                               int val, int val2)
+{
+       struct mma8452_data *data = iio_priv(indio_dev);
+       int ret, reg, steps;
+
+       switch (info) {
+       case IIO_EV_INFO_VALUE:
+               if (val < 0 || val > MMA8452_TRANSIENT_THS_MASK)
+                       return -EINVAL;
+
+               return mma8452_change_config(data, MMA8452_TRANSIENT_THS, val);
+
+       case IIO_EV_INFO_PERIOD:
+               steps = (val * USEC_PER_SEC + val2) /
+                               mma8452_transient_time_step_us[
+                                       mma8452_get_odr_index(data)];
+
+               if (steps < 0 || steps > 0xff)
+                       return -EINVAL;
+
+               return mma8452_change_config(data, MMA8452_TRANSIENT_COUNT,
+                                            steps);
+       case IIO_EV_INFO_HIGH_PASS_FILTER_3DB:
+               reg = i2c_smbus_read_byte_data(data->client,
+                                              MMA8452_TRANSIENT_CFG);
+               if (reg < 0)
+                       return reg;
+
+               if (val == 0 && val2 == 0) {
+                       reg |= MMA8452_TRANSIENT_CFG_HPF_BYP;
+               } else {
+                       reg &= ~MMA8452_TRANSIENT_CFG_HPF_BYP;
+                       ret = mma8452_set_hp_filter_frequency(data, val, val2);
+                       if (ret < 0)
+                               return ret;
+               }
+               return mma8452_change_config(data, MMA8452_TRANSIENT_CFG, reg);
+
+       default:
+               return -EINVAL;
+       }
+}
+
+static int mma8452_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 mma8452_data *data = iio_priv(indio_dev);
+       int ret;
+
+       ret = i2c_smbus_read_byte_data(data->client, MMA8452_TRANSIENT_CFG);
+       if (ret < 0)
+               return ret;
+
+       return ret & MMA8452_TRANSIENT_CFG_CHAN(chan->scan_index) ? 1 : 0;
+}
+
+static int mma8452_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 mma8452_data *data = iio_priv(indio_dev);
+       int val;
+
+       val = i2c_smbus_read_byte_data(data->client, MMA8452_TRANSIENT_CFG);
+       if (val < 0)
+               return val;
+
+       if (state)
+               val |= MMA8452_TRANSIENT_CFG_CHAN(chan->scan_index);
+       else
+               val &= ~MMA8452_TRANSIENT_CFG_CHAN(chan->scan_index);
+
+       val |= MMA8452_TRANSIENT_CFG_ELE;
+
+       return mma8452_change_config(data, MMA8452_TRANSIENT_CFG, val);
+}
+
+static void mma8452_transient_interrupt(struct iio_dev *indio_dev)
+{
+       struct mma8452_data *data = iio_priv(indio_dev);
+       s64 ts = iio_get_time_ns();
+       int src;
+
+       src = i2c_smbus_read_byte_data(data->client, MMA8452_TRANSIENT_SRC);
+       if (src < 0)
+               return;
+
+       if (src & MMA8452_TRANSIENT_SRC_XTRANSE)
+               iio_push_event(indio_dev,
+                              IIO_MOD_EVENT_CODE(IIO_ACCEL, 0, IIO_MOD_X,
+                                                 IIO_EV_TYPE_THRESH,
+                                                 IIO_EV_DIR_RISING),
+                              ts);
+
+       if (src & MMA8452_TRANSIENT_SRC_YTRANSE)
+               iio_push_event(indio_dev,
+                              IIO_MOD_EVENT_CODE(IIO_ACCEL, 0, IIO_MOD_Y,
+                                                 IIO_EV_TYPE_THRESH,
+                                                 IIO_EV_DIR_RISING),
+                              ts);
+
+       if (src & MMA8452_TRANSIENT_SRC_ZTRANSE)
+               iio_push_event(indio_dev,
+                              IIO_MOD_EVENT_CODE(IIO_ACCEL, 0, IIO_MOD_Z,
+                                                 IIO_EV_TYPE_THRESH,
+                                                 IIO_EV_DIR_RISING),
+                              ts);
+}
+
+static irqreturn_t mma8452_interrupt(int irq, void *p)
+{
+       struct iio_dev *indio_dev = p;
+       struct mma8452_data *data = iio_priv(indio_dev);
+       int ret = IRQ_NONE;
+       int src;
+
+       src = i2c_smbus_read_byte_data(data->client, MMA8452_INT_SRC);
+       if (src < 0)
+               return IRQ_NONE;
+
+       if (src & MMA8452_INT_DRDY) {
+               iio_trigger_poll_chained(indio_dev->trig);
+               ret = IRQ_HANDLED;
+       }
+
+       if (src & MMA8452_INT_TRANS) {
+               mma8452_transient_interrupt(indio_dev);
+               ret = IRQ_HANDLED;
+       }
+
+       return ret;
+}
+
 static irqreturn_t mma8452_trigger_handler(int irq, void *p)
 {
        struct iio_poll_func *pf = p;
@@ -291,6 +621,55 @@ done:
        return IRQ_HANDLED;
 }
 
+static int mma8452_reg_access_dbg(struct iio_dev *indio_dev,
+                                 unsigned reg, unsigned writeval,
+                                 unsigned *readval)
+{
+       int ret;
+       struct mma8452_data *data = iio_priv(indio_dev);
+
+       if (reg > MMA8452_MAX_REG)
+               return -EINVAL;
+
+       if (!readval)
+               return mma8452_change_config(data, reg, writeval);
+
+       ret = i2c_smbus_read_byte_data(data->client, reg);
+       if (ret < 0)
+               return ret;
+
+       *readval = ret;
+
+       return 0;
+}
+
+static const struct iio_event_spec mma8452_transient_event[] = {
+       {
+               .type = IIO_EV_TYPE_THRESH,
+               .dir = IIO_EV_DIR_RISING,
+               .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_HIGH_PASS_FILTER_3DB)
+       },
+};
+
+/*
+ * Threshold is configured in fixed 8G/127 steps regardless of
+ * currently selected scale for measurement.
+ */
+static IIO_CONST_ATTR_NAMED(accel_transient_scale, in_accel_scale, "0.617742");
+
+static struct attribute *mma8452_event_attributes[] = {
+       &iio_const_attr_accel_transient_scale.dev_attr.attr,
+       NULL,
+};
+
+static struct attribute_group mma8452_event_attribute_group = {
+       .attrs = mma8452_event_attributes,
+       .name = "events",
+};
+
 #define MMA8452_CHANNEL(axis, idx) { \
        .type = IIO_ACCEL, \
        .modified = 1, \
@@ -298,7 +677,8 @@ done:
        .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
                BIT(IIO_CHAN_INFO_CALIBBIAS), \
        .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
-               BIT(IIO_CHAN_INFO_SCALE), \
+               BIT(IIO_CHAN_INFO_SCALE) | \
+               BIT(IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY), \
        .scan_index = idx, \
        .scan_type = { \
                .sign = 's', \
@@ -307,6 +687,8 @@ done:
                .shift = 4, \
                .endianness = IIO_BE, \
        }, \
+       .event_spec = mma8452_transient_event, \
+       .num_event_specs = ARRAY_SIZE(mma8452_transient_event), \
 }
 
 static const struct iio_chan_spec mma8452_channels[] = {
@@ -319,6 +701,7 @@ static const struct iio_chan_spec mma8452_channels[] = {
 static struct attribute *mma8452_attributes[] = {
        &iio_dev_attr_sampling_frequency_available.dev_attr.attr,
        &iio_dev_attr_in_accel_scale_available.dev_attr.attr,
+       &iio_dev_attr_in_accel_filter_high_pass_3db_frequency_available.dev_attr.attr,
        NULL
 };
 
@@ -330,11 +713,107 @@ static const struct iio_info mma8452_info = {
        .attrs = &mma8452_group,
        .read_raw = &mma8452_read_raw,
        .write_raw = &mma8452_write_raw,
+       .event_attrs = &mma8452_event_attribute_group,
+       .read_event_value = &mma8452_read_thresh,
+       .write_event_value = &mma8452_write_thresh,
+       .read_event_config = &mma8452_read_event_config,
+       .write_event_config = &mma8452_write_event_config,
+       .debugfs_reg_access = &mma8452_reg_access_dbg,
        .driver_module = THIS_MODULE,
 };
 
 static const unsigned long mma8452_scan_masks[] = {0x7, 0};
 
+static int mma8452_data_rdy_trigger_set_state(struct iio_trigger *trig,
+                                             bool state)
+{
+       struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
+       struct mma8452_data *data = iio_priv(indio_dev);
+       int reg;
+
+       reg = i2c_smbus_read_byte_data(data->client, MMA8452_CTRL_REG4);
+       if (reg < 0)
+               return reg;
+
+       if (state)
+               reg |= MMA8452_INT_DRDY;
+       else
+               reg &= ~MMA8452_INT_DRDY;
+
+       return mma8452_change_config(data, MMA8452_CTRL_REG4, reg);
+}
+
+static int mma8452_validate_device(struct iio_trigger *trig,
+                                  struct iio_dev *indio_dev)
+{
+       struct iio_dev *indio = iio_trigger_get_drvdata(trig);
+
+       if (indio != indio_dev)
+               return -EINVAL;
+
+       return 0;
+}
+
+static const struct iio_trigger_ops mma8452_trigger_ops = {
+       .set_trigger_state = mma8452_data_rdy_trigger_set_state,
+       .validate_device = mma8452_validate_device,
+       .owner = THIS_MODULE,
+};
+
+static int mma8452_trigger_setup(struct iio_dev *indio_dev)
+{
+       struct mma8452_data *data = iio_priv(indio_dev);
+       struct iio_trigger *trig;
+       int ret;
+
+       trig = devm_iio_trigger_alloc(&data->client->dev, "%s-dev%d",
+                                     indio_dev->name,
+                                     indio_dev->id);
+       if (!trig)
+               return -ENOMEM;
+
+       trig->dev.parent = &data->client->dev;
+       trig->ops = &mma8452_trigger_ops;
+       iio_trigger_set_drvdata(trig, indio_dev);
+
+       ret = iio_trigger_register(trig);
+       if (ret)
+               return ret;
+
+       indio_dev->trig = trig;
+       return 0;
+}
+
+static void mma8452_trigger_cleanup(struct iio_dev *indio_dev)
+{
+       if (indio_dev->trig)
+               iio_trigger_unregister(indio_dev->trig);
+}
+
+static int mma8452_reset(struct i2c_client *client)
+{
+       int i;
+       int ret;
+
+       ret = i2c_smbus_write_byte_data(client, MMA8452_CTRL_REG2,
+                                       MMA8452_CTRL_REG2_RST);
+       if (ret < 0)
+               return ret;
+
+       for (i = 0; i < 10; i++) {
+               usleep_range(100, 200);
+               ret = i2c_smbus_read_byte_data(client, MMA8452_CTRL_REG2);
+               if (ret == -EIO)
+                       continue; /* I2C comm reset */
+               if (ret < 0)
+                       return ret;
+               if (!(ret & MMA8452_CTRL_REG2_RST))
+                       return 0;
+       }
+
+       return -ETIMEDOUT;
+}
+
 static int mma8452_probe(struct i2c_client *client,
                         const struct i2c_device_id *id)
 {
@@ -365,10 +844,7 @@ static int mma8452_probe(struct i2c_client *client,
        indio_dev->num_channels = ARRAY_SIZE(mma8452_channels);
        indio_dev->available_scan_masks = mma8452_scan_masks;
 
-       data->ctrl_reg1 = MMA8452_CTRL_ACTIVE |
-               (MMA8452_CTRL_DR_DEFAULT << MMA8452_CTRL_DR_SHIFT);
-       ret = i2c_smbus_write_byte_data(client, MMA8452_CTRL_REG1,
-               data->ctrl_reg1);
+       ret = mma8452_reset(client);
        if (ret < 0)
                return ret;
 
@@ -378,18 +854,77 @@ static int mma8452_probe(struct i2c_client *client,
        if (ret < 0)
                return ret;
 
+       /*
+        * By default set transient threshold to max to avoid events if
+        * enabling without configuring threshold.
+        */
+       ret = i2c_smbus_write_byte_data(client, MMA8452_TRANSIENT_THS,
+                                       MMA8452_TRANSIENT_THS_MASK);
+       if (ret < 0)
+               return ret;
+
+       if (client->irq) {
+               /*
+                * Although we enable the transient interrupt source once and
+                * for all here the transient event detection itself is not
+                * enabled until userspace asks for it by
+                * mma8452_write_event_config()
+                */
+               int supported_interrupts = MMA8452_INT_DRDY | MMA8452_INT_TRANS;
+               int enabled_interrupts = MMA8452_INT_TRANS;
+
+               /* Assume wired to INT1 pin */
+               ret = i2c_smbus_write_byte_data(client,
+                                               MMA8452_CTRL_REG5,
+                                               supported_interrupts);
+               if (ret < 0)
+                       return ret;
+
+               ret = i2c_smbus_write_byte_data(client,
+                                               MMA8452_CTRL_REG4,
+                                               enabled_interrupts);
+               if (ret < 0)
+                       return ret;
+
+               ret = mma8452_trigger_setup(indio_dev);
+               if (ret < 0)
+                       return ret;
+       }
+
+       data->ctrl_reg1 = MMA8452_CTRL_ACTIVE |
+               (MMA8452_CTRL_DR_DEFAULT << MMA8452_CTRL_DR_SHIFT);
+       ret = i2c_smbus_write_byte_data(client, MMA8452_CTRL_REG1,
+                                       data->ctrl_reg1);
+       if (ret < 0)
+               goto trigger_cleanup;
+
        ret = iio_triggered_buffer_setup(indio_dev, NULL,
                mma8452_trigger_handler, NULL);
        if (ret < 0)
-               return ret;
+               goto trigger_cleanup;
+
+       if (client->irq) {
+               ret = devm_request_threaded_irq(&client->dev,
+                                               client->irq,
+                                               NULL, mma8452_interrupt,
+                                               IRQF_TRIGGER_LOW | IRQF_ONESHOT,
+                                               client->name, indio_dev);
+               if (ret)
+                       goto buffer_cleanup;
+       }
 
        ret = iio_device_register(indio_dev);
        if (ret < 0)
                goto buffer_cleanup;
+
        return 0;
 
 buffer_cleanup:
        iio_triggered_buffer_cleanup(indio_dev);
+
+trigger_cleanup:
+       mma8452_trigger_cleanup(indio_dev);
+
        return ret;
 }
 
@@ -399,6 +934,7 @@ static int mma8452_remove(struct i2c_client *client)
 
        iio_device_unregister(indio_dev);
        iio_triggered_buffer_cleanup(indio_dev);
+       mma8452_trigger_cleanup(indio_dev);
        mma8452_standby(iio_priv(indio_dev));
 
        return 0;
@@ -433,6 +969,7 @@ static const struct of_device_id mma8452_dt_ids[] = {
        { .compatible = "fsl,mma8452" },
        { }
 };
+MODULE_DEVICE_TABLE(of, mma8452_dt_ids);
 
 static struct i2c_driver mma8452_driver = {
        .driver = {