Re: [PATCH v3 11/13] iio: imu: inv_icm42600: add accurate timestamping

Jonathan Cameron
2020-06-14T14:21:14Z

On Mon, 8 Jun 2020 22:42:48 +0200
Jean-Baptiste Maneyrol <jmaneyrol@invensense.com> wrote:

> Add a timestamping mechanism for buffer that provides accurate
> event timestamps when using watermark. This mechanism estimates
> device internal clock by comparing FIFO interrupts delta time and
> device elapsed time computed by parsing FIFO data.
>
> Take interrupt timestamp in hard irq handler and add IIO device
> specific timestamp structures in device private allocation.
>
> Signed-off-by: Jean-Baptiste Maneyrol <jmaneyrol@invensense.com>

As normal I'm going to wuss out on checking the maths in timestamp
calcs - it normally gives me a headache :)

So only remaining thing I think here is to leave it a bit longer
to give time for others to take a look + ideally a sanity check
/ review of the dt bindings.

Thanks

Jonathan

> ---
> drivers/iio/imu/inv_icm42600/Makefile | 1 +
> drivers/iio/imu/inv_icm42600/inv_icm42600.h | 5 +
> .../iio/imu/inv_icm42600/inv_icm42600_accel.c | 40 +++-
> .../imu/inv_icm42600/inv_icm42600_buffer.c | 28 +++
> .../iio/imu/inv_icm42600/inv_icm42600_core.c | 17 +-
> .../iio/imu/inv_icm42600/inv_icm42600_gyro.c | 40 +++-
> .../imu/inv_icm42600/inv_icm42600_timestamp.c | 195 ++++++++++++++++++
> .../imu/inv_icm42600/inv_icm42600_timestamp.h | 85 ++++++++
> 8 files changed, 396 insertions(+), 15 deletions(-)
> create mode 100644 drivers/iio/imu/inv_icm42600/inv_icm42600_timestamp.c
> create mode 100644 drivers/iio/imu/inv_icm42600/inv_icm42600_timestamp.h
>
> diff --git a/drivers/iio/imu/inv_icm42600/Makefile b/drivers/iio/imu/inv_icm42600/Makefile
> index 0f49f6df3647..291714d9aa54 100644
> --- a/drivers/iio/imu/inv_icm42600/Makefile
> +++ b/drivers/iio/imu/inv_icm42600/Makefile
> @@ -6,6 +6,7 @@ inv-icm42600-y += inv_icm42600_gyro.o
> inv-icm42600-y += inv_icm42600_accel.o
> inv-icm42600-y += inv_icm42600_temp.o
> inv-icm42600-y += inv_icm42600_buffer.o
> +inv-icm42600-y += inv_icm42600_timestamp.o
>
> obj-$(CONFIG_INV_ICM42600_I2C) += inv-icm42600-i2c.o
> inv-icm42600-i2c-y += inv_icm42600_i2c.o
> diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600.h b/drivers/iio/imu/inv_icm42600/inv_icm42600.h
> index 7b52d92739c3..c0f5059b13b3 100644
> --- a/drivers/iio/imu/inv_icm42600/inv_icm42600.h
> +++ b/drivers/iio/imu/inv_icm42600/inv_icm42600.h
> @@ -126,6 +126,7 @@ struct inv_icm42600_suspended {
> * @indio_accel: accelerometer IIO device.
> * @buffer: data transfer buffer aligned for DMA.
> * @fifo: FIFO management structure.
> + * @timestamp: interrupt timestamps.
> */
> struct inv_icm42600_state {
> struct mutex lock;
> @@ -141,6 +142,10 @@ struct inv_icm42600_state {
> struct iio_dev *indio_accel;
> uint8_t buffer[2] ____cacheline_aligned;
> struct inv_icm42600_fifo fifo;
> + struct {
> + int64_t gyro;
> + int64_t accel;
> + } timestamp;
> };
>
> /* Virtual register addresses: @bank on MSB (4 upper bits), @address on LSB */
> diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c b/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c
> index 77cdad99de91..e51e15029116 100644
> --- a/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c
> +++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_accel.c
> @@ -17,6 +17,7 @@
> #include "inv_icm42600.h"
> #include "inv_icm42600_temp.h"
> #include "inv_icm42600_buffer.h"
> +#include "inv_icm42600_timestamp.h"
>
> #define INV_ICM42600_ACCEL_CHAN(_modifier, _index, _ext_info) \
> { \
> @@ -50,6 +51,7 @@ enum inv_icm42600_accel_scan {
> INV_ICM42600_ACCEL_SCAN_Y,
> INV_ICM42600_ACCEL_SCAN_Z,
> INV_ICM42600_ACCEL_SCAN_TEMP,
> + INV_ICM42600_ACCEL_SCAN_TIMESTAMP,
> };
>
> static const struct iio_chan_spec_ext_info inv_icm42600_accel_ext_infos[] = {
> @@ -65,16 +67,18 @@ static const struct iio_chan_spec inv_icm42600_accel_channels[] = {
> INV_ICM42600_ACCEL_CHAN(IIO_MOD_Z, INV_ICM42600_ACCEL_SCAN_Z,
> inv_icm42600_accel_ext_infos),
> INV_ICM42600_TEMP_CHAN(INV_ICM42600_ACCEL_SCAN_TEMP),
> + IIO_CHAN_SOFT_TIMESTAMP(INV_ICM42600_ACCEL_SCAN_TIMESTAMP),
> };
>
> /*
> - * IIO buffer data: size must be a power of 2
> - * 8 bytes: 7 bytes data (accel 6 + temp 1) + 1 byte padding
> + * IIO buffer data: size must be a power of 2 and timestamp aligned
> + * 16 bytes: 7 bytes data (accel 6 + temp 1) + 1 byte padding + 8 bytes timestamp
> */
> struct inv_icm42600_accel_buffer {
> struct inv_icm42600_fifo_sensor_data accel;
> int8_t temp;
> uint8_t padding;
> + int64_t timestamp __aligned(8);
> };
>
> #define INV_ICM42600_SCAN_MASK_ACCEL_3AXIS \
> @@ -95,6 +99,7 @@ static int inv_icm42600_accel_update_scan_mode(struct iio_dev *indio_dev,
> const unsigned long *scan_mask)
> {
> struct inv_icm42600_state *st = iio_device_get_drvdata(indio_dev);
> + struct inv_icm42600_timestamp *ts = iio_priv(indio_dev);
> struct inv_icm42600_sensor_conf conf = INV_ICM42600_SENSOR_CONF_INIT;
> unsigned int fifo_en = 0;
> unsigned int sleep_temp = 0;
> @@ -122,6 +127,7 @@ static int inv_icm42600_accel_update_scan_mode(struct iio_dev *indio_dev,
> }
>
> /* update data FIFO write */
> + inv_icm42600_timestamp_apply_odr(ts, 0, 0, 0);
> ret = inv_icm42600_buffer_set_fifo_en(st, fifo_en | st->fifo.en);
> if (ret)
> goto out_unlock;
> @@ -302,9 +308,11 @@ static int inv_icm42600_accel_read_odr(struct inv_icm42600_state *st,
> return IIO_VAL_INT_PLUS_MICRO;
> }
>
> -static int inv_icm42600_accel_write_odr(struct inv_icm42600_state *st,
> +static int inv_icm42600_accel_write_odr(struct iio_dev *indio_dev,
> int val, int val2)
> {
> + struct inv_icm42600_state *st = iio_device_get_drvdata(indio_dev);
> + struct inv_icm42600_timestamp *ts = iio_priv(indio_dev);
> struct device *dev = regmap_get_device(st->map);
> unsigned int idx;
> struct inv_icm42600_sensor_conf conf = INV_ICM42600_SENSOR_CONF_INIT;
> @@ -323,6 +331,11 @@ static int inv_icm42600_accel_write_odr(struct inv_icm42600_state *st,
> pm_runtime_get_sync(dev);
> mutex_lock(&st->lock);
>
> + ret = inv_icm42600_timestamp_update_odr(ts, inv_icm42600_odr_to_period(conf.odr),
> + iio_buffer_enabled(indio_dev));
> + if (ret)
> + goto out_unlock;
> +
> ret = inv_icm42600_set_accel_conf(st, &conf, NULL);
> if (ret)
> goto out_unlock;
> @@ -612,7 +625,7 @@ static int inv_icm42600_accel_write_raw(struct iio_dev *indio_dev,
> iio_device_release_direct_mode(indio_dev);
> return ret;
> case IIO_CHAN_INFO_SAMP_FREQ:
> - return inv_icm42600_accel_write_odr(st, val, val2);
> + return inv_icm42600_accel_write_odr(indio_dev, val, val2);
> case IIO_CHAN_INFO_CALIBBIAS:
> ret = iio_device_claim_direct_mode(indio_dev);
> if (ret)
> @@ -695,6 +708,7 @@ struct iio_dev *inv_icm42600_accel_init(struct inv_icm42600_state *st)
> {
> struct device *dev = regmap_get_device(st->map);
> const char *name;
> + struct inv_icm42600_timestamp *ts;
> struct iio_dev *indio_dev;
> struct iio_buffer *buffer;
> int ret;
> @@ -703,7 +717,7 @@ struct iio_dev *inv_icm42600_accel_init(struct inv_icm42600_state *st)
> if (!name)
> return ERR_PTR(-ENOMEM);
>
> - indio_dev = devm_iio_device_alloc(dev, 0);
> + indio_dev = devm_iio_device_alloc(dev, sizeof(*ts));
> if (!indio_dev)
> return ERR_PTR(-ENOMEM);
>
> @@ -711,6 +725,9 @@ struct iio_dev *inv_icm42600_accel_init(struct inv_icm42600_state *st)
> if (!buffer)
> return ERR_PTR(-ENOMEM);
>
> + ts = iio_priv(indio_dev);
> + inv_icm42600_timestamp_init(ts, inv_icm42600_odr_to_period(st->conf.accel.odr));
> +
> iio_device_set_drvdata(indio_dev, st);
> indio_dev->name = name;
> indio_dev->info = &inv_icm42600_accel_info;
> @@ -732,17 +749,20 @@ struct iio_dev *inv_icm42600_accel_init(struct inv_icm42600_state *st)
> int inv_icm42600_accel_parse_fifo(struct iio_dev *indio_dev)
> {
> struct inv_icm42600_state *st = iio_device_get_drvdata(indio_dev);
> + struct inv_icm42600_timestamp *ts = iio_priv(indio_dev);
> ssize_t i, size;
> + unsigned int no;
> const void *accel, *gyro, *timestamp;
> const int8_t *temp;
> unsigned int odr;
> + int64_t ts_val;
> /* buffer is copied to userspace, set padding to 0 to avoid data leak */
> struct inv_icm42600_accel_buffer buffer = {
> .padding = 0,
> };
>
> /* parse all fifo packets */
> - for (i = 0; i < st->fifo.count; i += size) {
> + for (i = 0, no = 0; i < st->fifo.count; i += size, ++no) {
> size = inv_icm42600_fifo_decode_packet(&st->fifo.data[i],
> &accel, &gyro, &temp, &timestamp, &odr);
> /* quit if error or FIFO is empty */
> @@ -753,10 +773,16 @@ int inv_icm42600_accel_parse_fifo(struct iio_dev *indio_dev)
> if (accel == NULL || !inv_icm42600_fifo_is_data_valid(accel))
> continue;
>
> + /* update odr */
> + if (odr & INV_ICM42600_SENSOR_ACCEL)
> + inv_icm42600_timestamp_apply_odr(ts, st->fifo.period,
> + st->fifo.nb.total, no);
> +
> /* fill and push data buffer */
> memcpy(&buffer.accel, accel, sizeof(buffer.accel));
> buffer.temp = temp ? *temp : 0;
> - iio_push_to_buffers(indio_dev, &buffer);
> + ts_val = inv_icm42600_timestamp_pop(ts);
> + iio_push_to_buffers_with_timestamp(indio_dev, &buffer, ts_val);
> }
>
> return 0;
> diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_buffer.c b/drivers/iio/imu/inv_icm42600/inv_icm42600_buffer.c
> index e58e6f0c5698..99576b2c171f 100644
> --- a/drivers/iio/imu/inv_icm42600/inv_icm42600_buffer.c
> +++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_buffer.c
> @@ -13,6 +13,7 @@
> #include <linux/iio/buffer.h>
>
> #include "inv_icm42600.h"
> +#include "inv_icm42600_timestamp.h"
> #include "inv_icm42600_buffer.h"
>
> /* FIFO header: 1 byte */
> @@ -374,6 +375,7 @@ static int inv_icm42600_buffer_postdisable(struct iio_dev *indio_dev)
> struct device *dev = regmap_get_device(st->map);
> unsigned int sensor;
> unsigned int *watermark;
> + struct inv_icm42600_timestamp *ts;
> struct inv_icm42600_sensor_conf conf = INV_ICM42600_SENSOR_CONF_INIT;
> unsigned int sleep_temp = 0;
> unsigned int sleep_sensor = 0;
> @@ -383,9 +385,11 @@ static int inv_icm42600_buffer_postdisable(struct iio_dev *indio_dev)
> if (indio_dev == st->indio_gyro) {
> sensor = INV_ICM42600_SENSOR_GYRO;
> watermark = &st->fifo.watermark.gyro;
> + ts = iio_priv(st->indio_gyro);
> } else if (indio_dev == st->indio_accel) {
> sensor = INV_ICM42600_SENSOR_ACCEL;
> watermark = &st->fifo.watermark.accel;
> + ts = iio_priv(st->indio_accel);
> } else {
> return -EINVAL;
> }
> @@ -413,6 +417,8 @@ static int inv_icm42600_buffer_postdisable(struct iio_dev *indio_dev)
> if (!st->fifo.on)
> ret = inv_icm42600_set_temp_conf(st, false, &sleep_temp);
>
> + inv_icm42600_timestamp_reset(ts);
> +
> out_unlock:
> mutex_unlock(&st->lock);
>
> @@ -498,17 +504,26 @@ int inv_icm42600_buffer_fifo_read(struct inv_icm42600_state *st,
>
> int inv_icm42600_buffer_fifo_parse(struct inv_icm42600_state *st)
> {
> + struct inv_icm42600_timestamp *ts;
> int ret;
>
> if (st->fifo.nb.total == 0)
> return 0;
>
> + /* handle gyroscope timestamp and FIFO data parsing */
> + ts = iio_priv(st->indio_gyro);
> + inv_icm42600_timestamp_interrupt(ts, st->fifo.period, st->fifo.nb.total,
> + st->fifo.nb.gyro, st->timestamp.gyro);
> if (st->fifo.nb.gyro > 0) {
> ret = inv_icm42600_gyro_parse_fifo(st->indio_gyro);
> if (ret)
> return ret;
> }
>
> + /* handle accelerometer timestamp and FIFO data parsing */
> + ts = iio_priv(st->indio_accel);
> + inv_icm42600_timestamp_interrupt(ts, st->fifo.period, st->fifo.nb.total,
> + st->fifo.nb.accel, st->timestamp.accel);
> if (st->fifo.nb.accel > 0) {
> ret = inv_icm42600_accel_parse_fifo(st->indio_accel);
> if (ret)
> @@ -521,8 +536,13 @@ int inv_icm42600_buffer_fifo_parse(struct inv_icm42600_state *st)
> int inv_icm42600_buffer_hwfifo_flush(struct inv_icm42600_state *st,
> unsigned int count)
> {
> + struct inv_icm42600_timestamp *ts;
> + int64_t gyro_ts, accel_ts;
> int ret;
>
> + gyro_ts = iio_get_time_ns(st->indio_gyro);
> + accel_ts = iio_get_time_ns(st->indio_accel);
> +
> ret = inv_icm42600_buffer_fifo_read(st, count);
> if (ret)
> return ret;
> @@ -531,12 +551,20 @@ int inv_icm42600_buffer_hwfifo_flush(struct inv_icm42600_state *st,
> return 0;
>
> if (st->fifo.nb.gyro > 0) {
> + ts = iio_priv(st->indio_gyro);
> + inv_icm42600_timestamp_interrupt(ts, st->fifo.period,
> + st->fifo.nb.total, st->fifo.nb.gyro,
> + gyro_ts);
> ret = inv_icm42600_gyro_parse_fifo(st->indio_gyro);
> if (ret)
> return ret;
> }
>
> if (st->fifo.nb.accel > 0) {
> + ts = iio_priv(st->indio_accel);
> + inv_icm42600_timestamp_interrupt(ts, st->fifo.period,
> + st->fifo.nb.total, st->fifo.nb.accel,
> + accel_ts);
> ret = inv_icm42600_accel_parse_fifo(st->indio_accel);
> if (ret)
> return ret;
> diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_core.c b/drivers/iio/imu/inv_icm42600/inv_icm42600_core.c
> index 9e1f6e65fd45..8bd77185ccb7 100644
> --- a/drivers/iio/imu/inv_icm42600/inv_icm42600_core.c
> +++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_core.c
> @@ -19,6 +19,7 @@
>
> #include "inv_icm42600.h"
> #include "inv_icm42600_buffer.h"
> +#include "inv_icm42600_timestamp.h"
>
> static const struct regmap_range_cfg inv_icm42600_regmap_ranges[] = {
> {
> @@ -412,6 +413,16 @@ static int inv_icm42600_setup(struct inv_icm42600_state *st,
> return inv_icm42600_set_conf(st, hw->conf);
> }
>
> +static irqreturn_t inv_icm42600_irq_timestamp(int irq, void *_data)
> +{
> + struct inv_icm42600_state *st = _data;
> +
> + st->timestamp.gyro = iio_get_time_ns(st->indio_gyro);
> + st->timestamp.accel = iio_get_time_ns(st->indio_accel);
> +
> + return IRQ_WAKE_THREAD;
> +}
> +
> static irqreturn_t inv_icm42600_irq_handler(int irq, void *_data)
> {
> struct inv_icm42600_state *st = _data;
> @@ -495,7 +506,7 @@ static int inv_icm42600_irq_init(struct inv_icm42600_state *st, int irq,
> if (ret)
> return ret;
>
> - return devm_request_threaded_irq(dev, irq, NULL,
> + return devm_request_threaded_irq(dev, irq, inv_icm42600_irq_timestamp,
> inv_icm42600_irq_handler, irq_type,
> "inv_icm42600", st);
> }
> @@ -617,6 +628,10 @@ int inv_icm42600_core_probe(struct regmap *regmap, int chip, int irq,
> if (ret)
> return ret;
>
> + ret = inv_icm42600_timestamp_setup(st);
> + if (ret)
> + return ret;
> +
> ret = inv_icm42600_buffer_init(st);
> if (ret)
> return ret;
> diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c b/drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c
> index d53c604ae1de..1924b0b528df 100644
> --- a/drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c
> +++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_gyro.c
> @@ -17,6 +17,7 @@
> #include "inv_icm42600.h"
> #include "inv_icm42600_temp.h"
> #include "inv_icm42600_buffer.h"
> +#include "inv_icm42600_timestamp.h"
>
> #define INV_ICM42600_GYRO_CHAN(_modifier, _index, _ext_info) \
> { \
> @@ -50,6 +51,7 @@ enum inv_icm42600_gyro_scan {
> INV_ICM42600_GYRO_SCAN_Y,
> INV_ICM42600_GYRO_SCAN_Z,
> INV_ICM42600_GYRO_SCAN_TEMP,
> + INV_ICM42600_GYRO_SCAN_TIMESTAMP,
> };
>
> static const struct iio_chan_spec_ext_info inv_icm42600_gyro_ext_infos[] = {
> @@ -65,16 +67,18 @@ static const struct iio_chan_spec inv_icm42600_gyro_channels[] = {
> INV_ICM42600_GYRO_CHAN(IIO_MOD_Z, INV_ICM42600_GYRO_SCAN_Z,
> inv_icm42600_gyro_ext_infos),
> INV_ICM42600_TEMP_CHAN(INV_ICM42600_GYRO_SCAN_TEMP),
> + IIO_CHAN_SOFT_TIMESTAMP(INV_ICM42600_GYRO_SCAN_TIMESTAMP),
> };
>
> /*
> - * IIO buffer data: size must be a power of 2
> - * 8 bytes: 7 bytes data (gyro 6 + temp 1) + 1 byte padding
> + * IIO buffer data: size must be a power of 2 and timestamp aligned
> + * 16 bytes: 7 bytes data (gyro 6 + temp 1) + 1 byte padding + 8 bytes timestamp
> */
> struct inv_icm42600_gyro_buffer {
> struct inv_icm42600_fifo_sensor_data gyro;
> int8_t temp;
> uint8_t padding;
> + int64_t timestamp __aligned(8);
> };
>
> #define INV_ICM42600_SCAN_MASK_GYRO_3AXIS \
> @@ -95,6 +99,7 @@ static int inv_icm42600_gyro_update_scan_mode(struct iio_dev *indio_dev,
> const unsigned long *scan_mask)
> {
> struct inv_icm42600_state *st = iio_device_get_drvdata(indio_dev);
> + struct inv_icm42600_timestamp *ts = iio_priv(indio_dev);
> struct inv_icm42600_sensor_conf conf = INV_ICM42600_SENSOR_CONF_INIT;
> unsigned int fifo_en = 0;
> unsigned int sleep_gyro = 0;
> @@ -122,6 +127,7 @@ static int inv_icm42600_gyro_update_scan_mode(struct iio_dev *indio_dev,
> }
>
> /* update data FIFO write */
> + inv_icm42600_timestamp_apply_odr(ts, 0, 0, 0);
> ret = inv_icm42600_buffer_set_fifo_en(st, fifo_en | st->fifo.en);
> if (ret)
> goto out_unlock;
> @@ -314,9 +320,11 @@ static int inv_icm42600_gyro_read_odr(struct inv_icm42600_state *st,
> return IIO_VAL_INT_PLUS_MICRO;
> }
>
> -static int inv_icm42600_gyro_write_odr(struct inv_icm42600_state *st,
> +static int inv_icm42600_gyro_write_odr(struct iio_dev *indio_dev,
> int val, int val2)
> {
> + struct inv_icm42600_state *st = iio_device_get_drvdata(indio_dev);
> + struct inv_icm42600_timestamp *ts = iio_priv(indio_dev);
> struct device *dev = regmap_get_device(st->map);
> unsigned int idx;
> struct inv_icm42600_sensor_conf conf = INV_ICM42600_SENSOR_CONF_INIT;
> @@ -335,6 +343,11 @@ static int inv_icm42600_gyro_write_odr(struct inv_icm42600_state *st,
> pm_runtime_get_sync(dev);
> mutex_lock(&st->lock);
>
> + ret = inv_icm42600_timestamp_update_odr(ts, inv_icm42600_odr_to_period(conf.odr),
> + iio_buffer_enabled(indio_dev));
> + if (ret)
> + goto out_unlock;
> +
> ret = inv_icm42600_set_gyro_conf(st, &conf, NULL);
> if (ret)
> goto out_unlock;
> @@ -623,7 +636,7 @@ static int inv_icm42600_gyro_write_raw(struct iio_dev *indio_dev,
> iio_device_release_direct_mode(indio_dev);
> return ret;
> case IIO_CHAN_INFO_SAMP_FREQ:
> - return inv_icm42600_gyro_write_odr(st, val, val2);
> + return inv_icm42600_gyro_write_odr(indio_dev, val, val2);
> case IIO_CHAN_INFO_CALIBBIAS:
> ret = iio_device_claim_direct_mode(indio_dev);
> if (ret)
> @@ -706,6 +719,7 @@ struct iio_dev *inv_icm42600_gyro_init(struct inv_icm42600_state *st)
> {
> struct device *dev = regmap_get_device(st->map);
> const char *name;
> + struct inv_icm42600_timestamp *ts;
> struct iio_dev *indio_dev;
> struct iio_buffer *buffer;
> int ret;
> @@ -714,7 +728,7 @@ struct iio_dev *inv_icm42600_gyro_init(struct inv_icm42600_state *st)
> if (!name)
> return ERR_PTR(-ENOMEM);
>
> - indio_dev = devm_iio_device_alloc(dev, 0);
> + indio_dev = devm_iio_device_alloc(dev, sizeof(*ts));
> if (!indio_dev)
> return ERR_PTR(-ENOMEM);
>
> @@ -722,6 +736,9 @@ struct iio_dev *inv_icm42600_gyro_init(struct inv_icm42600_state *st)
> if (!buffer)
> return ERR_PTR(-ENOMEM);
>
> + ts = iio_priv(indio_dev);
> + inv_icm42600_timestamp_init(ts, inv_icm42600_odr_to_period(st->conf.gyro.odr));
> +
> iio_device_set_drvdata(indio_dev, st);
> indio_dev->name = name;
> indio_dev->info = &inv_icm42600_gyro_info;
> @@ -743,17 +760,20 @@ struct iio_dev *inv_icm42600_gyro_init(struct inv_icm42600_state *st)
> int inv_icm42600_gyro_parse_fifo(struct iio_dev *indio_dev)
> {
> struct inv_icm42600_state *st = iio_device_get_drvdata(indio_dev);
> + struct inv_icm42600_timestamp *ts = iio_priv(indio_dev);
> ssize_t i, size;
> + unsigned int no;
> const void *accel, *gyro, *timestamp;
> const int8_t *temp;
> unsigned int odr;
> + int64_t ts_val;
> /* buffer is copied to userspace, set padding to 0 to avoid data leak */
> struct inv_icm42600_gyro_buffer buffer = {
> .padding = 0,
> };
>
> /* parse all fifo packets */
> - for (i = 0; i < st->fifo.count; i += size) {
> + for (i = 0, no = 0; i < st->fifo.count; i += size, ++no) {
> size = inv_icm42600_fifo_decode_packet(&st->fifo.data[i],
> &accel, &gyro, &temp, &timestamp, &odr);
> /* quit if error or FIFO is empty */
> @@ -764,10 +784,16 @@ int inv_icm42600_gyro_parse_fifo(struct iio_dev *indio_dev)
> if (gyro == NULL || !inv_icm42600_fifo_is_data_valid(gyro))
> continue;
>
> + /* update odr */
> + if (odr & INV_ICM42600_SENSOR_GYRO)
> + inv_icm42600_timestamp_apply_odr(ts, st->fifo.period,
> + st->fifo.nb.total, no);
> +
> /* fill and push data buffer */
> memcpy(&buffer.gyro, gyro, sizeof(buffer.gyro));
> buffer.temp = temp ? *temp : 0;
> - iio_push_to_buffers(indio_dev, &buffer);
> + ts_val = inv_icm42600_timestamp_pop(ts);
> + iio_push_to_buffers_with_timestamp(indio_dev, &buffer, ts_val);
> }
>
> return 0;
> diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_timestamp.c b/drivers/iio/imu/inv_icm42600/inv_icm42600_timestamp.c
> new file mode 100644
> index 000000000000..7f2dc41f807b
> --- /dev/null
> +++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_timestamp.c
> @@ -0,0 +1,195 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (C) 2020 Invensense, Inc.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/regmap.h>
> +#include <linux/math64.h>
> +
> +#include "inv_icm42600.h"
> +#include "inv_icm42600_timestamp.h"
> +
> +/* internal chip period is 32kHz, 31250ns */
> +#define INV_ICM42600_TIMESTAMP_PERIOD 31250
> +/* allow a jitter of +/- 2% */
> +#define INV_ICM42600_TIMESTAMP_JITTER 2
> +/* compute min and max periods accepted */
> +#define INV_ICM42600_TIMESTAMP_MIN_PERIOD(_p) \
> + (((_p) * (100 - INV_ICM42600_TIMESTAMP_JITTER)) / 100)
> +#define INV_ICM42600_TIMESTAMP_MAX_PERIOD(_p) \
> + (((_p) * (100 + INV_ICM42600_TIMESTAMP_JITTER)) / 100)
> +
> +/* Add a new value inside an accumulator and update the estimate value */
> +static void inv_update_acc(struct inv_icm42600_timestamp_acc *acc, uint32_t val)
> +{
> + uint64_t sum = 0;
> + size_t i;
> +
> + acc->values[acc->idx++] = val;
> + if (acc->idx >= ARRAY_SIZE(acc->values))
> + acc->idx = 0;
> +
> + /* compute the mean of all stored values, use 0 as empty slot */
> + for (i = 0; i < ARRAY_SIZE(acc->values); ++i) {
> + if (acc->values[i] == 0)
> + break;
> + sum += acc->values[i];
> + }
> +
> + acc->val = div_u64(sum, i);
> +}
> +
> +void inv_icm42600_timestamp_init(struct inv_icm42600_timestamp *ts,
> + uint32_t period)
> +{
> + /* initial odr for sensor after reset is 1kHz */
> + const uint32_t default_period = 1000000;
> +
> + /* current multiplier and period values after reset */
> + ts->mult = default_period / INV_ICM42600_TIMESTAMP_PERIOD;
> + ts->period = default_period;
> + /* new set multiplier is the one from chip initialization */
> + ts->new_mult = period / INV_ICM42600_TIMESTAMP_PERIOD;
> +
> + /* use theoretical value for chip period */
> + inv_update_acc(&ts->chip_period, INV_ICM42600_TIMESTAMP_PERIOD);
> +}
> +
> +int inv_icm42600_timestamp_setup(struct inv_icm42600_state *st)
> +{
> + unsigned int val;
> +
> + /* enable timestamp register */
> + val = INV_ICM42600_TMST_CONFIG_TMST_TO_REGS_EN |
> + INV_ICM42600_TMST_CONFIG_TMST_EN;
> + return regmap_update_bits(st->map, INV_ICM42600_REG_TMST_CONFIG,
> + INV_ICM42600_TMST_CONFIG_MASK, val);
> +}
> +
> +int inv_icm42600_timestamp_update_odr(struct inv_icm42600_timestamp *ts,
> + uint32_t period, bool fifo)
> +{
> + /* when FIFO is on, prevent odr change if one is already pending */
> + if (fifo && ts->new_mult != 0)
> + return -EAGAIN;
> +
> + ts->new_mult = period / INV_ICM42600_TIMESTAMP_PERIOD;
> +
> + return 0;
> +}
> +
> +static bool inv_validate_period(uint32_t period, uint32_t mult)
> +{
> + const uint32_t chip_period = INV_ICM42600_TIMESTAMP_PERIOD;
> + uint32_t period_min, period_max;
> +
> + /* check that period is acceptable */
> + period_min = INV_ICM42600_TIMESTAMP_MIN_PERIOD(chip_period) * mult;
> + period_max = INV_ICM42600_TIMESTAMP_MAX_PERIOD(chip_period) * mult;
> + if (period > period_min && period < period_max)
> + return true;
> + else
> + return false;
> +}
> +
> +static bool inv_compute_chip_period(struct inv_icm42600_timestamp *ts,
> + uint32_t mult, uint32_t period)
> +{
> + uint32_t new_chip_period;
> +
> + if (!inv_validate_period(period, mult))
> + return false;
> +
> + /* update chip internal period estimation */
> + new_chip_period = period / mult;
> + inv_update_acc(&ts->chip_period, new_chip_period);
> +
> + return true;
> +}
> +
> +void inv_icm42600_timestamp_interrupt(struct inv_icm42600_timestamp *ts,
> + uint32_t fifo_period, size_t fifo_nb,
> + size_t sensor_nb, int64_t timestamp)
> +{
> + struct inv_icm42600_timestamp_interval *it;
> + int64_t delta, interval;
> + const uint32_t fifo_mult = fifo_period / INV_ICM42600_TIMESTAMP_PERIOD;
> + uint32_t period = ts->period;
> + int32_t m;
> + bool valid = false;
> +
> + if (fifo_nb == 0)
> + return;
> +
> + /* update interrupt timestamp and compute chip and sensor periods */
> + it = &ts->it;
> + it->lo = it->up;
> + it->up = timestamp;
> + delta = it->up - it->lo;
> + if (it->lo != 0) {
> + /* compute period: delta time divided by number of samples */
> + period = div_s64(delta, fifo_nb);
> + valid = inv_compute_chip_period(ts, fifo_mult, period);
> + /* update sensor period if chip internal period is updated */
> + if (valid)
> + ts->period = ts->mult * ts->chip_period.val;
> + }
> +
> + /* no previous data, compute theoritical value from interrupt */
> + if (ts->timestamp == 0) {
> + /* elapsed time: sensor period * sensor samples number */
> + interval = (int64_t)ts->period * (int64_t)sensor_nb;
> + ts->timestamp = it->up - interval;
> + return;
> + }
> +
> + /* if interrupt interval is valid, sync with interrupt timestamp */
> + if (valid) {
> + /* compute measured fifo_period */
> + fifo_period = fifo_mult * ts->chip_period.val;
> + /* delta time between last sample and last interrupt */
> + delta = it->lo - ts->timestamp;
> + /* if there are multiple samples, go back to first one */
> + while (delta >= (fifo_period * 3 / 2))
> + delta -= fifo_period;
> + /* compute maximal adjustment value */
> + m = INV_ICM42600_TIMESTAMP_MAX_PERIOD(ts->period) - ts->period;
> + if (delta > m)
> + delta = m;
> + else if (delta < -m)
> + delta = -m;
> + ts->timestamp += delta;
> + }
> +}
> +
> +void inv_icm42600_timestamp_apply_odr(struct inv_icm42600_timestamp *ts,
> + uint32_t fifo_period, size_t fifo_nb,
> + unsigned int fifo_no)
> +{
> + int64_t interval;
> + uint32_t fifo_mult;
> +
> + if (ts->new_mult == 0)
> + return;
> +
> + /* update to new multiplier and update period */
> + ts->mult = ts->new_mult;
> + ts->new_mult = 0;
> + ts->period = ts->mult * ts->chip_period.val;
> +
> + /*
> + * After ODR change the time interval with the previous sample is
> + * undertermined (depends when the change occures). So we compute the
> + * timestamp from the current interrupt using the new FIFO period, the
> + * total number of samples and the current sample numero.
> + */
> + if (ts->timestamp != 0) {
> + /* compute measured fifo period */
> + fifo_mult = fifo_period / INV_ICM42600_TIMESTAMP_PERIOD;
> + fifo_period = fifo_mult * ts->chip_period.val;
> + /* computes time interval between interrupt and this sample */
> + interval = (int64_t)(fifo_nb - fifo_no) * (int64_t)fifo_period;
> + ts->timestamp = ts->it.up - interval;
> + }
> +}
> diff --git a/drivers/iio/imu/inv_icm42600/inv_icm42600_timestamp.h b/drivers/iio/imu/inv_icm42600/inv_icm42600_timestamp.h
> new file mode 100644
> index 000000000000..4e4f331d4fe4
> --- /dev/null
> +++ b/drivers/iio/imu/inv_icm42600/inv_icm42600_timestamp.h
> @@ -0,0 +1,85 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +/*
> + * Copyright (C) 2020 Invensense, Inc.
> + */
> +
> +#ifndef INV_ICM42600_TIMESTAMP_H_
> +#define INV_ICM42600_TIMESTAMP_H_
> +
> +#include <linux/kernel.h>
> +
> +struct inv_icm42600_state;
> +
> +/**
> + * struct inv_icm42600_timestamp_interval - timestamps interval
> + * @lo: interval lower bound
> + * @up: interval upper bound
> + */
> +struct inv_icm42600_timestamp_interval {
> + int64_t lo;
> + int64_t up;
> +};
> +
> +/**
> + * struct inv_icm42600_timestamp_acc - accumulator for computing an estimation
> + * @val: current estimation of the value, the mean of all values
> + * @idx: current index of the next free place in values table
> + * @values: table of all measured values, use for computing the mean
> + */
> +struct inv_icm42600_timestamp_acc {
> + uint32_t val;
> + size_t idx;
> + uint32_t values[32];
> +};
> +
> +/**
> + * struct inv_icm42600_timestamp - timestamp management states
> + * @it: interrupts interval timestamps
> + * @timestamp: store last timestamp for computing next data timestamp
> + * @mult: current internal period multiplier
> + * @new_mult: new set internal period multiplier (not yet effective)
> + * @period: measured current period of the sensor
> + * @chip_period: accumulator for computing internal chip period
> + */
> +struct inv_icm42600_timestamp {
> + struct inv_icm42600_timestamp_interval it;
> + int64_t timestamp;
> + uint32_t mult;
> + uint32_t new_mult;
> + uint32_t period;
> + struct inv_icm42600_timestamp_acc chip_period;
> +};
> +
> +void inv_icm42600_timestamp_init(struct inv_icm42600_timestamp *ts,
> + uint32_t period);
> +
> +int inv_icm42600_timestamp_setup(struct inv_icm42600_state *st);
> +
> +int inv_icm42600_timestamp_update_odr(struct inv_icm42600_timestamp *ts,
> + uint32_t period, bool fifo);
> +
> +void inv_icm42600_timestamp_interrupt(struct inv_icm42600_timestamp *ts,
> + uint32_t fifo_period, size_t fifo_nb,
> + size_t sensor_nb, int64_t timestamp);
> +
> +static inline int64_t
> +inv_icm42600_timestamp_pop(struct inv_icm42600_timestamp *ts)
> +{
> + ts->timestamp += ts->period;
> + return ts->timestamp;
> +}
> +
> +void inv_icm42600_timestamp_apply_odr(struct inv_icm42600_timestamp *ts,
> + uint32_t fifo_period, size_t fifo_nb,
> + unsigned int fifo_no);
> +
> +static inline void
> +inv_icm42600_timestamp_reset(struct inv_icm42600_timestamp *ts)
> +{
> + const struct inv_icm42600_timestamp_interval interval_init = {0LL, 0LL};
> +
> + ts->it = interval_init;
> + ts->timestamp = 0;
> +}
> +
> +#endif