Re: [PATCH v4] iio: mma8452: add freefall detection for Freescale's accelerometers

From: Peter Meerwald-Stadler
Date: Wed Jan 13 2016 - 08:53:55 EST

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In reply to: Martin Kepplinger: "[PATCH v4] iio: mma8452: add freefall detection for Freescale's accelerometers"
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Hello,

> This adds freefall event detection to the supported devices. It adds
> the in_accel_x&y&z_mag_falling_en iio event attribute, which activates
> freefall mode.
>
> In freefall mode, the current acceleration magnitude (AND combination
> of all axis values) is compared to the specified threshold.
> If it falls under the threshold (in_accel_mag_falling_value),
> the appropriate IIO event code is generated.
>
> This is what the sysfs "events" directory for these devices looks
> like after this change:
>
> -rw-r--r-- 4096 Oct 23 08:45 in_accel_mag_falling_period
> -rw-r--r-- 4096 Oct 23 08:45 in_accel_mag_falling_value
> -rw-r--r-- 4096 Oct 23 08:45 in_accel_mag_rising_period
> -rw-r--r-- 4096 Oct 23 08:45 in_accel_mag_rising_value
> -r--r--r-- 4096 Oct 23 08:45 in_accel_scale
> -rw-r--r-- 4096 Oct 23 08:45 in_accel_x&y&z_mag_falling_en
> -rw-r--r-- 4096 Oct 23 08:45 in_accel_x_mag_rising_en
> -rw-r--r-- 4096 Oct 23 08:45 in_accel_y_mag_rising_en
> -rw-r--r-- 4096 Oct 23 08:45 in_accel_z_mag_rising_en

I think it is a very good idea to have this for review, thanks!

minor comments below

> Signed-off-by: Martin Kepplinger <martin.kepplinger@xxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Christoph Muellner <christoph.muellner@xxxxxxxxxxxxxxxxxxxxx>
> ---
> revision history
> ----------------
> v1:
> initial post
> v2:
> build all from correct event and channel spec structs
> v3:
> rising and falling are treated as equal now. Until last time, I had
> misunderstood the iio events' user API definition. This works and
> values always reflect the current state of operation.
> v4:
> fix error that caused a build warning
>
> drivers/iio/accel/mma8452.c | 156 +++++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 139 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
> index ccc632a..9534c3a 100644
> --- a/drivers/iio/accel/mma8452.c
> +++ b/drivers/iio/accel/mma8452.c
> @@ -15,7 +15,7 @@
> *
> * 7-bit I2C slave address 0x1c/0x1d (pin selectable)
> *
> - * TODO: orientation / freefall events, autosleep
> + * TODO: orientation events, autosleep
> */
>
> #include <linux/module.h>
> @@ -416,6 +416,46 @@ fail:
> return ret;
> }
>
> +static int mma8452_freefall_mode_enabled(struct mma8452_data *data)
> +{
> + int val;
> + const struct mma_chip_info *chip = data->chip_info;
> +
> + val = i2c_smbus_read_byte_data(data->client, chip->ev_cfg);
> + if (val < 0)
> + return val;
> +
> + return !(val & MMA8452_FF_MT_CFG_OAE);

I'd appreciate a comment what the possible return values of this function
are and their purpose

> +}
> +
> +static int mma8452_set_freefall_mode(struct mma8452_data *data, u8 state)

state seems to be used as a bool, maybe it should be bool

> +{
> + int val, ret;

strictly, only one of the two variable is necessary

> + const struct mma_chip_info *chip = data->chip_info;
> +
> + val = i2c_smbus_read_byte_data(data->client, chip->ev_cfg);
> + if (val < 0)
> + return val;
> +
> + if (state && !(mma8452_freefall_mode_enabled(data))) {
> + val |= BIT(idx_x + chip->ev_cfg_chan_shift);
> + val |= BIT(idx_y + chip->ev_cfg_chan_shift);
> + val |= BIT(idx_z + chip->ev_cfg_chan_shift);
> + val &= ~MMA8452_FF_MT_CFG_OAE;
> + } else if (!state && mma8452_freefall_mode_enabled(data)) {
> + val &= ~BIT(idx_x + chip->ev_cfg_chan_shift);
> + val &= ~BIT(idx_y + chip->ev_cfg_chan_shift);
> + val &= ~BIT(idx_z + chip->ev_cfg_chan_shift);
> + val |= MMA8452_FF_MT_CFG_OAE;
> + }
> +
> + ret = mma8452_change_config(data, chip->ev_cfg, val);
> + if (ret)
> + return ret;
> +
> + return 0;
> +}
> +
> static int mma8452_set_hp_filter_frequency(struct mma8452_data *data,
> int val, int val2)
> {
> @@ -609,12 +649,22 @@ static int mma8452_read_event_config(struct iio_dev *indio_dev,

I find the return values of this functions difficult to understand,
comment would be good

> const struct mma_chip_info *chip = data->chip_info;
> int ret;
>
> - ret = i2c_smbus_read_byte_data(data->client,
> - data->chip_info->ev_cfg);
> - if (ret < 0)
> - return ret;
> + switch (dir) {
> + case IIO_EV_DIR_FALLING:
> + return mma8452_freefall_mode_enabled(data);
> + case IIO_EV_DIR_RISING:
> + if (mma8452_freefall_mode_enabled(data))
> + return 0;
> +
> + ret = i2c_smbus_read_byte_data(data->client,
> + data->chip_info->ev_cfg);
> + if (ret < 0)
> + return ret;
>
> - return !!(ret & BIT(chan->scan_index + chip->ev_cfg_chan_shift));
> + return !!(ret & BIT(chan->scan_index + chip->ev_cfg_chan_shift));
> + default:
> + return -EINVAL;
> + }
> }
>
> static int mma8452_write_event_config(struct iio_dev *indio_dev,
> @@ -627,19 +677,34 @@ static int mma8452_write_event_config(struct iio_dev *indio_dev,
> const struct mma_chip_info *chip = data->chip_info;
> int val;
>
> - val = i2c_smbus_read_byte_data(data->client, chip->ev_cfg);
> - if (val < 0)
> - return val;
> -
> - if (state)
> - val |= BIT(chan->scan_index + chip->ev_cfg_chan_shift);
> - else
> - val &= ~BIT(chan->scan_index + chip->ev_cfg_chan_shift);
> + switch (dir) {
> + case IIO_EV_DIR_FALLING:
> + return mma8452_set_freefall_mode(data, state);
> + case IIO_EV_DIR_RISING:
> + val = i2c_smbus_read_byte_data(data->client, chip->ev_cfg);
> + if (val < 0)
> + return val;
> +
> + if (state) {
> + if (mma8452_freefall_mode_enabled(data)) {
> + val &= ~BIT(idx_x + chip->ev_cfg_chan_shift);
> + val &= ~BIT(idx_y + chip->ev_cfg_chan_shift);
> + val &= ~BIT(idx_z + chip->ev_cfg_chan_shift);
> + val |= MMA8452_FF_MT_CFG_OAE;
> + }
> + val |= BIT(chan->scan_index + chip->ev_cfg_chan_shift);
> + } else {
> + if (mma8452_freefall_mode_enabled(data))
> + return -EBUSY;
> + val &= ~BIT(chan->scan_index + chip->ev_cfg_chan_shift);
> + }
>
> - val |= chip->ev_cfg_ele;
> - val |= MMA8452_FF_MT_CFG_OAE;
> + val |= chip->ev_cfg_ele;
>
> - return mma8452_change_config(data, chip->ev_cfg, val);
> + return mma8452_change_config(data, chip->ev_cfg, val);
> + default:
> + return -EINVAL;
> + }
> }
>
> static void mma8452_transient_interrupt(struct iio_dev *indio_dev)
> @@ -652,6 +717,16 @@ static void mma8452_transient_interrupt(struct iio_dev *indio_dev)
> if (src < 0)
> return;
>
> + if (mma8452_freefall_mode_enabled(data)) {
> + iio_push_event(indio_dev,
> + IIO_MOD_EVENT_CODE(IIO_ACCEL, 0,
> + IIO_MOD_X_AND_Y_AND_Z,
> + IIO_EV_TYPE_MAG,
> + IIO_EV_DIR_FALLING),
> + ts);
> + return;
> + }
> +
> if (src & data->chip_info->ev_src_xe)
> iio_push_event(indio_dev,
> IIO_MOD_EVENT_CODE(IIO_ACCEL, 0, IIO_MOD_X,
> @@ -745,6 +820,27 @@ static int mma8452_reg_access_dbg(struct iio_dev *indio_dev,
> return 0;
> }
>
> +static const struct iio_event_spec mma8452_freefall_event[] = {
> + {
> + .type = IIO_EV_TYPE_MAG,
> + .dir = IIO_EV_DIR_FALLING,
> + .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)
> + },
> +};
> +
> +static const struct iio_event_spec mma8652_freefall_event[] = {
> + {
> + .type = IIO_EV_TYPE_MAG,
> + .dir = IIO_EV_DIR_FALLING,
> + .mask_separate = BIT(IIO_EV_INFO_ENABLE),
> + .mask_shared_by_type = BIT(IIO_EV_INFO_VALUE) |
> + BIT(IIO_EV_INFO_PERIOD)
> + },
> +};
> +
> static const struct iio_event_spec mma8452_transient_event[] = {
> {
> .type = IIO_EV_TYPE_MAG,
> @@ -781,6 +877,24 @@ static struct attribute_group mma8452_event_attribute_group = {
> .attrs = mma8452_event_attributes,
> };
>
> +#define MMA8452_FREEFALL_CHANNEL(modifier) { \
> + .type = IIO_ACCEL, \
> + .modified = 1, \
> + .channel2 = modifier, \
> + .scan_index = -1, \
> + .event_spec = mma8452_freefall_event, \
> + .num_event_specs = ARRAY_SIZE(mma8452_freefall_event), \
> +}
> +
> +#define MMA8652_FREEFALL_CHANNEL(modifier) { \
> + .type = IIO_ACCEL, \
> + .modified = 1, \
> + .channel2 = modifier, \
> + .scan_index = -1, \
> + .event_spec = mma8652_freefall_event, \
> + .num_event_specs = ARRAY_SIZE(mma8652_freefall_event), \
> +}
> +
> #define MMA8452_CHANNEL(axis, idx, bits) { \
> .type = IIO_ACCEL, \
> .modified = 1, \
> @@ -827,6 +941,7 @@ static const struct iio_chan_spec mma8452_channels[] = {
> MMA8452_CHANNEL(Y, idx_y, 12),
> MMA8452_CHANNEL(Z, idx_z, 12),
> IIO_CHAN_SOFT_TIMESTAMP(idx_ts),
> + MMA8452_FREEFALL_CHANNEL(IIO_MOD_X_AND_Y_AND_Z),
> };
>
> static const struct iio_chan_spec mma8453_channels[] = {
> @@ -834,6 +949,7 @@ static const struct iio_chan_spec mma8453_channels[] = {
> MMA8452_CHANNEL(Y, idx_y, 10),
> MMA8452_CHANNEL(Z, idx_z, 10),
> IIO_CHAN_SOFT_TIMESTAMP(idx_ts),
> + MMA8452_FREEFALL_CHANNEL(IIO_MOD_X_AND_Y_AND_Z),
> };
>
> static const struct iio_chan_spec mma8652_channels[] = {
> @@ -841,6 +957,7 @@ static const struct iio_chan_spec mma8652_channels[] = {
> MMA8652_CHANNEL(Y, idx_y, 12),
> MMA8652_CHANNEL(Z, idx_z, 12),
> IIO_CHAN_SOFT_TIMESTAMP(idx_ts),
> + MMA8652_FREEFALL_CHANNEL(IIO_MOD_X_AND_Y_AND_Z),
> };
>
> static const struct iio_chan_spec mma8653_channels[] = {
> @@ -848,6 +965,7 @@ static const struct iio_chan_spec mma8653_channels[] = {
> MMA8652_CHANNEL(Y, idx_y, 10),
> MMA8652_CHANNEL(Z, idx_z, 10),
> IIO_CHAN_SOFT_TIMESTAMP(idx_ts),
> + MMA8652_FREEFALL_CHANNEL(IIO_MOD_X_AND_Y_AND_Z),
> };
>
> enum {
> @@ -1190,6 +1308,10 @@ static int mma8452_probe(struct i2c_client *client,
> if (ret < 0)
> goto buffer_cleanup;
>
> + ret = mma8452_set_freefall_mode(data, 0);
> + if (ret)
> + return ret;
> +
> return 0;
>
> buffer_cleanup:
>

--

Peter Meerwald-Stadler
+43-664-2444418 (mobile)

Next message: Karol Herbst: "Re: [PATCH] drm: nouveau: fix nouveau_debugfs_init prototype"
Previous message: Mark Rutland: "Re: [PATCH v3 07/21] arm64: move kernel image to base of vmalloc area"
In reply to: Martin Kepplinger: "[PATCH v4] iio: mma8452: add freefall detection for Freescale's accelerometers"
Next in thread: Martin Kepplinger: "Re: [PATCH v4] iio: mma8452: add freefall detection for Freescale's accelerometers"
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