On Tue, Mar 24, 2020 at 10:28 PM Gwendal Grignou <gwendal@xxxxxxxxxxxx> wrote: > > This patchset adds a sensorhub driver for spreading sensor > events coming from the Embedded controller sensor FIFO: > > +---------------+ +--------------+ +---- > | cros_ec_accel | | cros_ec_gyro | | ... > +---------------+ +--------------+ +---- > id:0 \ id:1 | / id:.. > +------------------------------+ > | cros-ec-sensorhub | > +------------------------------+ > | cros_ec_dev | > +------------------------------+ > | cros_ec_i2c, cros_ec_lpc, .. | > +------------------------------+ > | > EC > > When new sensors events are present, the EC raises and interrupt, > sensorhub reads the FIFO and uses the 'id' field to spread the event to > the proper IIO sensors. This stack is similar to the HID sensor input > stack. > > The patch set allows the host to receive MEMS sensor sample > asynchronously from ChromeOS Emebedded Controller (EC). > > Given the EC and the host are not synchronized, the timestamp generated > by the EC drifts and the AP interrupt latency adds variable delay. > > When events arrive, the driver stores the time of the interrupt and use > that information to convert the timestamp from the EC time domain to the > AP time domain. To prevent the errors from the interrupt time variation, > a median filter smooth the timestamp generation and prevents timestamps > to go in the past. > > When a batch of sensor events arrives, the sensor hub ring code spreads > the timestamps. > > The buffer interaface is presentid through the IIO ABI. > And extra parameter - flush - (presents on HID and ST sensor hub > implementation) force the EC to send accumulated events in its queue, > without waiting for buffer hwfifo_timeout to expire. > > To access sensor data, we can use iio_readdev like: > iio_readdev -T 10000 -s 4 -b 2 iio:device4 > > When FIFO is not supported by the EC, a trigger is present in the > directory. After registering a trigger, setting sampling_frequency, > the latest data collected by the sensor will be retrieved by the host > when the trigger expires. > > When cros_ec_accel_legacy driver is used, no FIFO is supported and the > sampling frequency for the accelerometers is hard coded at 10Hz. > Acked-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx> # for drivers/platform/chrome bits > Gwendal Grignou (11): > platform: chrome: sensorhub: Add FIFO support > platform: chrome: sensorhub: Add code to spread timestmap > platform: chrome: sensorhub: Add median filter > iio: cros_ec: Move function description to .c file > iio: expose iio_device_set_clock > iio: cros_ec: Register to cros_ec_sensorhub when EC supports FIFO > iio: cros_ec: Remove pm function > iio: cros_ec: Expose hwfifo_timeout > iio: cros_ec: Report hwfifo_watermark_max > iio: cros_ec: Use Hertz as unit for sampling frequency > iio: cros_ec: flush as hwfifo attribute > > drivers/iio/accel/cros_ec_accel_legacy.c | 8 +- > .../cros_ec_sensors/cros_ec_lid_angle.c | 3 +- > .../common/cros_ec_sensors/cros_ec_sensors.c | 13 +- > .../cros_ec_sensors/cros_ec_sensors_core.c | 404 +++++-- > drivers/iio/industrialio-core.c | 8 +- > drivers/iio/light/cros_ec_light_prox.c | 15 +- > drivers/iio/pressure/cros_ec_baro.c | 14 +- > drivers/platform/chrome/Makefile | 4 +- > drivers/platform/chrome/cros_ec_sensorhub.c | 107 +- > .../platform/chrome/cros_ec_sensorhub_ring.c | 1002 +++++++++++++++++ > .../linux/iio/common/cros_ec_sensors_core.h | 104 +- > include/linux/iio/iio.h | 2 + > .../linux/platform_data/cros_ec_sensorhub.h | 166 +++ > 13 files changed, 1612 insertions(+), 238 deletions(-) > create mode 100644 drivers/platform/chrome/cros_ec_sensorhub_ring.c > > -- > 2.25.1.696.g5e7596f4ac-goog > -- With Best Regards, Andy Shevchenko
