| Message ID | 20200324202736.243314-1-gwendal@chromium.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | Cros EC sensor hub FIFO support | expand |
On Tue, Mar 24, 2020 at 10:28 PM Gwendal Grignou <gwendal@chromium.org> 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@gmail.com> # 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 >
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. 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