Re: [PATCH v4 13/17] iio: cros_ec: Register to cros_ec_sensorhub when EC supports FIFO

[Gwendal Grignou <gwendal@chromium.org>]

The problem are:- in case of a kernel crash while collecting sensor
data: when the kernel restart, the sensors are still sending events. -
we can also enable a sensor behind the iiio driver back through debug
tools: we don

On Sun, Nov 10, 2019 at 5:17 AM Jonathan Cameron <jic23@kernel.org> wrote:
>
> On Tue,  5 Nov 2019 14:26:48 -0800
> Gwendal Grignou <gwendal@chromium.org> wrote:
>
> > When EC supports FIFO, each IIO device registers a callback, to put
> > samples in the buffer when they arrives from the FIFO.
> > We can still use a trigger to collect samples, but there may be some
> > duplications in the buffer: EC has a single FIFO, so once one sensor is
> > using it, all sensors event will be in the FIFO.
> > To be sure events generated by cros_ec_sensorhub or the trigger uses the
> > same time domain, current_timestamp_clock must be set to "boottime".
>
> How is that enforced?
I should have removed this comment: cros_ec_sensors_push_data() now
checks for the iio dev clock_id and add an offset if necessary.
I add a patch for IIO to allow changing timestamp_clock from the
driver itself: I set to default for cros ec sensor to boottime, since
it is the default timestamp source coming from the FIFO.

>  I'd have no problem with core support for IIO
> to allow a driver that has requirements like this to override
> the normal flexibility.
>
> >
> > When no FIFO, the user space app needs to call trigger_new, or better
> > register a high precision timer.
> >
> > Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
> A question + a comment that I'm still not happy with the fact we have
> to protect against a race on startup.  However, we can perhaps make that
> a problem for another day.
>
> Assuming the question on the mode mask change is resolved.
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>
> > ---
> > Changes in v4:
> > - Fix a logic error when the sensor is not "physical", for instance lig
> >   angle: core_init() would return !0 even if there was no error.
> > - Check patch with --strict option
> >     Use sizeof(*obj) instead of sizeof(struct ...obj)
> >     Alignement
> > Change in v3:
> > - Remove double line
> > - Fix indentation
> > - Add code to support iio clock_id setting. Optimized for
> >   CLOCK_BOOTTIME.
> > Change in v2 from "Use triggered buffer only when EC does not support
> > FIFO":
> > - Keep trigger all the time.
> > - Add  devm_add_action to cleanup callback registration.
> > - EC that "reports" legacy sensors do not have FIFO.
> > - Use iiio_is_buffer_enabled instead of checking the scan_mask
> >   before sending samples to buffer.
> > - Add empty lines for visibility.
> >
> >  drivers/iio/accel/cros_ec_accel_legacy.c      |  8 +-
> >  .../cros_ec_sensors/cros_ec_lid_angle.c       |  2 +-
> >  .../common/cros_ec_sensors/cros_ec_sensors.c  |  9 +-
> >  .../cros_ec_sensors/cros_ec_sensors_core.c    | 85 ++++++++++++++++++-
> >  drivers/iio/light/cros_ec_light_prox.c        |  9 +-
> >  drivers/iio/pressure/cros_ec_baro.c           |  9 +-
> >  .../linux/iio/common/cros_ec_sensors_core.h   | 10 ++-
> >  7 files changed, 103 insertions(+), 29 deletions(-)
> >
> > diff --git a/drivers/iio/accel/cros_ec_accel_legacy.c b/drivers/iio/accel/cros_ec_accel_legacy.c
> > index 65f85faf6f31..b9f651e4ce99 100644
> > --- a/drivers/iio/accel/cros_ec_accel_legacy.c
> > +++ b/drivers/iio/accel/cros_ec_accel_legacy.c
> > @@ -171,7 +171,8 @@ static int cros_ec_accel_legacy_probe(struct platform_device *pdev)
> >       if (!indio_dev)
> >               return -ENOMEM;
> >
> > -     ret = cros_ec_sensors_core_init(pdev, indio_dev, true);
> > +     ret = cros_ec_sensors_core_init(pdev, indio_dev, true,
> > +                                     cros_ec_sensors_capture, NULL);
> >       if (ret)
> >               return ret;
> >
> > @@ -191,11 +192,6 @@ static int cros_ec_accel_legacy_probe(struct platform_device *pdev)
> >               state->sign[CROS_EC_SENSOR_Z] = -1;
> >       }
> >
> > -     ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
> > -                     cros_ec_sensors_capture, NULL);
> > -     if (ret)
> > -             return ret;
> > -
> >       return devm_iio_device_register(dev, indio_dev);
> >  }
> >
> > diff --git a/drivers/iio/common/cros_ec_sensors/cros_ec_lid_angle.c b/drivers/iio/common/cros_ec_sensors/cros_ec_lid_angle.c
> > index 1dcc2a16ab2d..e30a59fcf0f9 100644
> > --- a/drivers/iio/common/cros_ec_sensors/cros_ec_lid_angle.c
> > +++ b/drivers/iio/common/cros_ec_sensors/cros_ec_lid_angle.c
> > @@ -97,7 +97,7 @@ static int cros_ec_lid_angle_probe(struct platform_device *pdev)
> >       if (!indio_dev)
> >               return -ENOMEM;
> >
> > -     ret = cros_ec_sensors_core_init(pdev, indio_dev, false);
> > +     ret = cros_ec_sensors_core_init(pdev, indio_dev, false, NULL, NULL);
> >       if (ret)
> >               return ret;
> >
> > diff --git a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c
> > index 7dce04473467..62a0dd970988 100644
> > --- a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c
> > +++ b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors.c
> > @@ -231,7 +231,9 @@ static int cros_ec_sensors_probe(struct platform_device *pdev)
> >       if (!indio_dev)
> >               return -ENOMEM;
> >
> > -     ret = cros_ec_sensors_core_init(pdev, indio_dev, true);
> > +     ret = cros_ec_sensors_core_init(pdev, indio_dev, true,
> > +                                     cros_ec_sensors_capture,
> > +                                     cros_ec_sensors_push_data);
> >       if (ret)
> >               return ret;
> >
> > @@ -293,11 +295,6 @@ static int cros_ec_sensors_probe(struct platform_device *pdev)
> >       else
> >               state->core.read_ec_sensors_data = cros_ec_sensors_read_cmd;
> >
> > -     ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
> > -                     cros_ec_sensors_capture, NULL);
> > -     if (ret)
> > -             return ret;
> > -
> >       return devm_iio_device_register(dev, indio_dev);
> >  }
> >
> > diff --git a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c
> > index b47da497a3c3..904cd26dd31f 100644
> > --- a/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c
> > +++ b/drivers/iio/common/cros_ec_sensors/cros_ec_sensors_core.c
> > @@ -12,6 +12,7 @@
> >  #include <linux/iio/iio.h>
> >  #include <linux/iio/kfifo_buf.h>
> >  #include <linux/iio/trigger_consumer.h>
> > +#include <linux/iio/triggered_buffer.h>
> >  #include <linux/kernel.h>
> >  #include <linux/mfd/cros_ec.h>
> >  #include <linux/module.h>
> > @@ -83,17 +84,78 @@ static void get_default_min_max_freq(enum motionsensor_type type,
> >       }
> >  }
> >
> > +int cros_ec_sensors_push_data(struct iio_dev *indio_dev,
> > +                           s16 *data,
> > +                           s64 timestamp)
> > +{
> > +     struct cros_ec_sensors_core_state *st = iio_priv(indio_dev);
> > +     s16 *out;
> > +     s64 delta;
> > +     unsigned int i;
> > +
> > +     /*
> > +      * It can happen if we get a samples before the iio device is fully
> > +      * registered.
>
> I'd really like to stop that happening as it seems like a nasty racey corner case.
> I'm not convinced there aren't 'half registered' cases we can still hit even
> with this protection.  Hardware should be in a clean state before any
> interrupts etc are registered.
You're right, st can not be null, since devm_iio_device_alloc is
called before cros_ec_sensors_core_init that register the callback.
>
> However if you are sure this protection is enough that can be a job for another day.
>
> I suspect you get away with it because of the next check always failing in
> those racey conditions as can't enable the buffer until we have a fully
> set up device.
>
> > +      */
> > +     if (!st)
> > +             return 0;
> > +
> > +     /*
> > +      * Ignore samples if the buffer is not set: it is needed if the ODR is
> > +      * set but the buffer is not enabled yet.
> > +      */
> > +     if (!iio_buffer_enabled(indio_dev))
> > +             return 0;
This check is necessary:
- in case of a kernel crash while collecting sensor data: when the
kernel restart, the sensors are still sending events.
- we can also enable a sensor behind the iiio driver back through
debug tools: the sensor will send sample, but the iio driver is not
ready for them.
> > +
> > +     out = (s16 *)st->samples;
> > +     for_each_set_bit(i,
> > +                      indio_dev->active_scan_mask,
> > +                      indio_dev->masklength) {
> > +             *out = data[i];
> > +             out++;
> > +     }
> > +
> > +     if (iio_device_get_clock(indio_dev) != CLOCK_BOOTTIME)
> > +             delta = iio_get_time_ns(indio_dev) - cros_ec_get_time_ns();
> > +     else
> > +             delta = 0;
> > +
> > +     iio_push_to_buffers_with_timestamp(indio_dev, st->samples,
> > +                                        timestamp + delta);
> > +
> > +     return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(cros_ec_sensors_push_data);
> > +
> > +static void cros_ec_sensors_core_clean(void *arg)
> > +{
> > +     struct platform_device *pdev = (struct platform_device *)arg;
> > +     struct cros_ec_sensorhub *sensor_hub =
> > +             dev_get_drvdata(pdev->dev.parent);
> > +     struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> > +     struct cros_ec_sensors_core_state *st = iio_priv(indio_dev);
> > +     u8 sensor_num = st->param.info.sensor_num;
> > +
> > +     cros_ec_sensorhub_unregister_push_data(sensor_hub, sensor_num);
> > +}
> > +
> >  /**
> >   * cros_ec_sensors_core_init() - basic initialization of the core structure
> >   * @pdev:            platform device created for the sensors
> >   * @indio_dev:               iio device structure of the device
> >   * @physical_device: true if the device refers to a physical device
> > + * @trigger_capture:    function pointer to call buffer is triggered,
> > + *    for backward compatibility.
> > + * @push_data:          function to call when cros_ec_sensorhub receives
> > + *    a sample for that sensor.
> >   *
> >   * Return: 0 on success, -errno on failure.
> >   */
> >  int cros_ec_sensors_core_init(struct platform_device *pdev,
> >                             struct iio_dev *indio_dev,
> > -                           bool physical_device)
> > +                           bool physical_device,
> > +                           cros_ec_sensors_capture_t trigger_capture,
> > +                           cros_ec_sensorhub_push_data_cb_t push_data)
> >  {
> >       struct device *dev = &pdev->dev;
> >       struct cros_ec_sensors_core_state *state = iio_priv(indio_dev);
> > @@ -132,8 +194,6 @@ int cros_ec_sensors_core_init(struct platform_device *pdev,
> >       indio_dev->name = pdev->name;
> >
> >       if (physical_device) {
> > -             indio_dev->modes = INDIO_DIRECT_MODE;
> > -
>
> This particular changes seems odd. Are we dropping access via sysfs?
> From what I recall we don't actually do much with this currently in the
> IIO core, but we 'might' in future ;)
Should not have been removed.

>
> >               state->param.cmd = MOTIONSENSE_CMD_INFO;
> >               state->param.info.sensor_num = sensor_platform->sensor_num;
> >               ret = cros_ec_motion_send_host_cmd(state, 0);
> > @@ -162,6 +222,25 @@ int cros_ec_sensors_core_init(struct platform_device *pdev,
> >                       state->frequencies[2] =
> >                           state->resp->info_3.max_frequency;
> >               }
> > +
> > +             ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
> > +                                                   trigger_capture, NULL);
> > +             if (ret)
> > +                     return ret;
> > +
> > +             if (cros_ec_check_features(ec, EC_FEATURE_MOTION_SENSE_FIFO)) {
> > +                     ret = cros_ec_sensorhub_register_push_data(sensor_hub,
> > +                                             sensor_platform->sensor_num,
> > +                                             indio_dev, push_data);
> > +                     if (ret)
> > +                             return ret;
> > +
> > +                     ret = devm_add_action_or_reset(dev,
> > +                                             cros_ec_sensors_core_clean,
> > +                                             pdev);
> > +                     if (ret)
> > +                             return ret;
> > +             }
> >       }
> >
> >       return 0;
> > diff --git a/drivers/iio/light/cros_ec_light_prox.c b/drivers/iio/light/cros_ec_light_prox.c
> > index d85a391e50c5..698b2ee81ebf 100644
> > --- a/drivers/iio/light/cros_ec_light_prox.c
> > +++ b/drivers/iio/light/cros_ec_light_prox.c
> > @@ -178,7 +178,9 @@ static int cros_ec_light_prox_probe(struct platform_device *pdev)
> >       if (!indio_dev)
> >               return -ENOMEM;
> >
> > -     ret = cros_ec_sensors_core_init(pdev, indio_dev, true);
> > +     ret = cros_ec_sensors_core_init(pdev, indio_dev, true,
> > +                                     cros_ec_sensors_capture,
> > +                                     cros_ec_sensors_push_data);
> >       if (ret)
> >               return ret;
> >
> > @@ -237,11 +239,6 @@ static int cros_ec_light_prox_probe(struct platform_device *pdev)
> >
> >       state->core.read_ec_sensors_data = cros_ec_sensors_read_cmd;
> >
> > -     ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
> > -                                           cros_ec_sensors_capture, NULL);
> > -     if (ret)
> > -             return ret;
> > -
> >       return devm_iio_device_register(dev, indio_dev);
> >  }
> >
> > diff --git a/drivers/iio/pressure/cros_ec_baro.c b/drivers/iio/pressure/cros_ec_baro.c
> > index 2354302375de..e1c86b22676c 100644
> > --- a/drivers/iio/pressure/cros_ec_baro.c
> > +++ b/drivers/iio/pressure/cros_ec_baro.c
> > @@ -134,7 +134,9 @@ static int cros_ec_baro_probe(struct platform_device *pdev)
> >       if (!indio_dev)
> >               return -ENOMEM;
> >
> > -     ret = cros_ec_sensors_core_init(pdev, indio_dev, true);
> > +     ret = cros_ec_sensors_core_init(pdev, indio_dev, true,
> > +                                     cros_ec_sensors_capture,
> > +                                     cros_ec_sensors_push_data);
> >       if (ret)
> >               return ret;
> >
> > @@ -180,11 +182,6 @@ static int cros_ec_baro_probe(struct platform_device *pdev)
> >
> >       state->core.read_ec_sensors_data = cros_ec_sensors_read_cmd;
> >
> > -     ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
> > -                                           cros_ec_sensors_capture, NULL);
> > -     if (ret)
> > -             return ret;
> > -
> >       return devm_iio_device_register(dev, indio_dev);
> >  }
> >
> > diff --git a/include/linux/iio/common/cros_ec_sensors_core.h b/include/linux/iio/common/cros_ec_sensors_core.h
> > index 0af918978f97..b8f573ca9dcc 100644
> > --- a/include/linux/iio/common/cros_ec_sensors_core.h
> > +++ b/include/linux/iio/common/cros_ec_sensors_core.h
> > @@ -12,6 +12,7 @@
> >  #include <linux/irqreturn.h>
> >  #include <linux/platform_data/cros_ec_commands.h>
> >  #include <linux/platform_data/cros_ec_proto.h>
> > +#include <linux/platform_data/cros_ec_sensorhub.h>
> >
> >  enum {
> >       CROS_EC_SENSOR_X,
> > @@ -32,6 +33,8 @@ enum {
> >  /* Minimum sampling period to use when device is suspending */
> >  #define CROS_EC_MIN_SUSPEND_SAMPLING_FREQUENCY 1000  /* 1 second */
> >
> > +typedef irqreturn_t (*cros_ec_sensors_capture_t)(int irq, void *p);
> > +
> >  /**
> >   * struct cros_ec_sensors_core_state - state data for EC sensors IIO driver
> >   * @ec:                              cros EC device structure
> > @@ -87,9 +90,14 @@ int cros_ec_sensors_read_cmd(struct iio_dev *indio_dev, unsigned long scan_mask,
> >
> >  struct platform_device;
> >  int cros_ec_sensors_core_init(struct platform_device *pdev,
> > -                           struct iio_dev *indio_dev, bool physical_device);
> > +                           struct iio_dev *indio_dev, bool physical_device,
> > +                           cros_ec_sensors_capture_t trigger_capture,
> > +                           cros_ec_sensorhub_push_data_cb_t push_data);
> >
> >  irqreturn_t cros_ec_sensors_capture(int irq, void *p);
> > +int cros_ec_sensors_push_data(struct iio_dev *indio_dev,
> > +                           s16 *data,
> > +                           s64 timestamp);
> >
> >  int cros_ec_motion_send_host_cmd(struct cros_ec_sensors_core_state *st,
> >                                u16 opt_length);
>