Re: [PATCH v2 1/1] counter: cros_ec: Add synchronization sensor

Fabien Lahoudere
2019-08-29T11:10:57Z

Le lundi 26 août 2019 à 09:56 +0100, Jonathan Cameron a écrit :
> On Fri, 23 Aug 2019 14:41:27 +0200
> Fabien Lahoudere <fabien.lahoudere@collabora.com> wrote:
>
> > From: Gwendal Grignou <gwendal@chromium.org>
> >
> > EC returns a counter when there is an event on camera vsync.
> > This patch comes from chromeos kernel 4.4
> >
> > Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
> > Signed-off-by: Fabien Lahoudere <fabien.lahoudere@collabora.com>
> >
> > CROS EC sync sensor was originally designed as an IIO device.
> > Now that the counter subsystem will replace IIO_COUNTER, we
> > have to implement a new way to get sync count.
>
> I'm curious. What is this counter used for?

It is a counter of a pin connected to a camera vsync.
It is used to manage correct orientation of the camera when the
gyroscope detect a change.

>
> This combined counter and iio driver isn't something we would
> normally
> want to support. What is the reasoning behind doing both interfaces?

That patch was originally designed using only IIO with IIO_count and
IIO_TIMESTAMP channel. As IIO_COUNT is deprecated, we need to use the
new counter subsystem. So I just split the driver in two part counter
and iio timestamp.

However after your email I did some investigation and did not find any
use of the timestamp for that sensor. Timestamp is just a common
channel implemented on all CROS EC sensors.

So I think I will drop it now and if a timestamp is needed, I will
probably restart the discussion about timestamp in the counter
subsystemif that make sense to have one.

Thanks

Fabien

>
> > Signed-off-by: Fabien Lahoudere <fabien.lahoudere@collabora.com>
> > ---
> > Documentation/driver-api/generic-counter.rst | 3 +
> > MAINTAINERS | 7 +
> > drivers/counter/Kconfig | 9 +
> > drivers/counter/Makefile | 1 +
> > drivers/counter/counter.c | 2 +
> > drivers/counter/cros_ec_sensors_sync.c | 208
> > ++++++++++++++++++
> > .../cros_ec_sensors/cros_ec_sensors_core.c | 1 +
> > drivers/mfd/cros_ec_dev.c | 3 +
> > include/linux/counter.h | 1 +
> > 9 files changed, 235 insertions(+)
> > create mode 100644 drivers/counter/cros_ec_sensors_sync.c
> >
> > diff --git a/Documentation/driver-api/generic-counter.rst
> > b/Documentation/driver-api/generic-counter.rst
> > index 8382f01a53e3..beb80714ac8b 100644
> > --- a/Documentation/driver-api/generic-counter.rst
> > +++ b/Documentation/driver-api/generic-counter.rst
> > @@ -44,6 +44,9 @@ Counter interface provides the following
> > available count data types:
> > * COUNT_POSITION:
> > Unsigned integer value representing position.
> >
> > +* COUNT_TALLY:
> > + Unsigned integer value representing tally.
> > +
> > A Count has a count function mode which represents the update
> > behavior
> > for the count data. The Generic Counter interface provides the
> > following
> > available count function modes:
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index e60f5c361969..83bd291d103e 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -3902,6 +3902,13 @@ R: Guenter Roeck <groeck@chromium.org>
> > F: Documentation/devicetree/bindings/sound/google,cros-ec-
> > codec.txt
> > F: sound/soc/codecs/cros_ec_codec.*
> >
> > +CHROMEOS EC COUNTER DRIVER
> > +M: Fabien Lahoudere <fabien.lahoudere@collabora.com>
> > +M: William Breathitt Gray <vilhelm.gray@gmail.com>
> > +L: linux-iio@vger.kernel.org
> > +S: Maintained
> > +F: drivers/counter/cros_ec_sensors_sync.c
> > +
> > CIRRUS LOGIC AUDIO CODEC DRIVERS
> > M: Brian Austin <brian.austin@cirrus.com>
> > M: Paul Handrigan <Paul.Handrigan@cirrus.com>
> > diff --git a/drivers/counter/Kconfig b/drivers/counter/Kconfig
> > index 2967d0a9ff91..22287f5715e5 100644
> > --- a/drivers/counter/Kconfig
> > +++ b/drivers/counter/Kconfig
> > @@ -59,4 +59,13 @@ config FTM_QUADDEC
> > To compile this driver as a module, choose M here: the
> > module will be called ftm-quaddec.
> >
> > +config IIO_CROS_EC_SENSORS_SYNC
> > + tristate "ChromeOS EC Counter Sensors"
> > + depends on IIO_CROS_EC_SENSORS_CORE && IIO
> > + help
> > + Module to handle synchronisation sensors presented by the
> > ChromeOS EC
> > + Sensor hub.
> > + Synchronisation sensors are counter sensors triggered when
> > events
> > + occurs from other subsystems.
> > +
> > endif # COUNTER
> > diff --git a/drivers/counter/Makefile b/drivers/counter/Makefile
> > index 40d35522937d..6fe4c98a446f 100644
> > --- a/drivers/counter/Makefile
> > +++ b/drivers/counter/Makefile
> > @@ -9,3 +9,4 @@ obj-$(CONFIG_104_QUAD_8) += 104-quad-8.o
> > obj-$(CONFIG_STM32_TIMER_CNT) += stm32-timer-cnt.o
> > obj-$(CONFIG_STM32_LPTIMER_CNT) += stm32-lptimer-cnt.o
> > obj-$(CONFIG_FTM_QUADDEC) += ftm-quaddec.o
> > +obj-$(CONFIG_IIO_CROS_EC_SENSORS_SYNC) += cros_ec_sensors_sync.o
> > diff --git a/drivers/counter/counter.c b/drivers/counter/counter.c
> > index 106bc7180cd8..53525b109094 100644
> > --- a/drivers/counter/counter.c
> > +++ b/drivers/counter/counter.c
> > @@ -261,6 +261,7 @@ void counter_count_read_value_set(struct
> > counter_count_read_value *const val,
> > {
> > switch (type) {
> > case COUNTER_COUNT_POSITION:
> > + case COUNTER_COUNT_TALLY:
> > val->len = sprintf(val->buf, "%lu\n", *(unsigned long
> > *)data);
> > break;
> > default:
> > @@ -290,6 +291,7 @@ int counter_count_write_value_get(void *const
> > data,
> >
> > switch (type) {
> > case COUNTER_COUNT_POSITION:
> > + case COUNTER_COUNT_TALLY:
> > err = kstrtoul(val->buf, 0, data);
> > if (err)
> > return err;
> > diff --git a/drivers/counter/cros_ec_sensors_sync.c
> > b/drivers/counter/cros_ec_sensors_sync.c
> > new file mode 100644
> > index 000000000000..b6f5e2c6da9f
> > --- /dev/null
> > +++ b/drivers/counter/cros_ec_sensors_sync.c
> > @@ -0,0 +1,208 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Driver of counter incremented after events on interrupt line in
> > EC.
> > + *
> > + * Copyright 2018 Google, Inc
> > + */
> > +
> > +#include <linux/device.h>
> > +#include <linux/counter.h>
> > +#include <linux/iio/common/cros_ec_sensors_core.h>
> > +#include <linux/iio/triggered_buffer.h>
> > +#include <linux/kernel.h>
> > +#include <linux/mfd/cros_ec.h>
> > +#include <linux/module.h>
> > +#include <linux/platform_device.h>
> > +
> > +#define DRV_NAME "cros-ec-sync"
> > +
> > +/*
> > + * One channel for counter, the other for timestamp.
> > + */
> > +#define MAX_CHANNELS (1)
> > +
> > +/* State data for ec_sensors iio driver. */
> > +struct cros_ec_sensors_sync_state {
> > + /* Shared by all sensors */
> > + struct cros_ec_sensors_core_state core;
> > + struct counter_device counter;
> > + struct iio_chan_spec channels[MAX_CHANNELS];
> > +};
> > +
> > +static int cros_ec_sensors_sync_read(struct iio_dev *indio_dev,
> > + struct iio_chan_spec const *chan,
> > + int *val, int *val2, long mask)
> > +{
> > + struct cros_ec_sensors_sync_state *st = iio_priv(indio_dev);
> > + u16 data;
> > + int ret;
> > +
> > + mutex_lock(&st->core.cmd_lock);
> > + switch (mask) {
> > + case IIO_CHAN_INFO_RAW:
> > + ret = cros_ec_sensors_read_cmd(indio_dev, BIT(0),
> > &data);
> > + if (ret < 0)
> > + break;
> > + ret = IIO_VAL_INT;
> > + *val = data;
> > + break;
> > + default:
> > + ret = cros_ec_sensors_core_read(&st->core, chan, val,
> > val2,
> > + mask);
> > + break;
> > + }
> > + mutex_unlock(&st->core.cmd_lock);
> > + return ret;
> > +}
> > +
> > +static struct iio_info cros_ec_sensors_sync_info = {
> > + .read_raw = &cros_ec_sensors_sync_read,
> > + .read_avail = &cros_ec_sensors_core_read_avail,
> > +};
> > +
> > +static struct counter_count cros_ec_sync_counts = {
> > + .id = 0,
> > + .name = "Cros EC sync counter",
> > +};
> > +
> > +static int cros_ec_sync_cnt_read(struct counter_device *counter,
> > + struct counter_count *count,
> > + struct counter_count_read_value *val)
> > +{
> > + s16 cnt;
> > + int ret;
> > + struct iio_dev *indio_dev = counter->priv;
> > + struct cros_ec_sensors_sync_state *const st =
> > iio_priv(indio_dev);
> > + unsigned long data;
> > +
> > + mutex_lock(&st->core.cmd_lock);
> > + ret = cros_ec_sensors_read_cmd(indio_dev, BIT(0), &cnt);
> > + mutex_unlock(&st->core.cmd_lock);
> > + if (ret != 0) {
> > + dev_warn(&indio_dev->dev, "Unable to read sensor
> > data\n");
> > + return ret;
> > + }
> > +
> > + data = (unsigned long) cnt;
> > + counter_count_read_value_set(val, COUNTER_COUNT_TALLY, &data);
> > +
> > + return 0;
> > +}
> > +
> > +static const struct counter_ops cros_ec_sync_cnt_ops = {
> > + .count_read = cros_ec_sync_cnt_read,
> > +};
> > +
> > +static char *cros_ec_loc[] = {
> > + [MOTIONSENSE_LOC_BASE] = "base",
> > + [MOTIONSENSE_LOC_LID] = "lid",
> > + [MOTIONSENSE_LOC_CAMERA] = "camera",
> > + [MOTIONSENSE_LOC_MAX] = "unknown",
> > +};
> > +
> > +static ssize_t cros_ec_sync_id(struct counter_device *counter,
> > + void *private, char *buf)
> > +{
> > + struct iio_dev *indio_dev = counter->priv;
> > + struct cros_ec_sensors_sync_state *const st =
> > iio_priv(indio_dev);
> > +
> > + return snprintf(buf, PAGE_SIZE, "%d\n", st-
> > >core.param.info.sensor_num);
> > +}
> > +
> > +static ssize_t cros_ec_sync_loc(struct counter_device *counter,
> > + void *private, char *buf)
> > +{
> > + struct iio_dev *indio_dev = counter->priv;
> > + struct cros_ec_sensors_sync_state *const st =
> > iio_priv(indio_dev);
> > +
> > + return snprintf(buf, PAGE_SIZE, "%s\n", cros_ec_loc[st-
> > >core.loc]);
> > +}
> > +
> > +static struct counter_device_ext cros_ec_sync_cnt_ext[] = {
> > + {
> > + .name = "id",
> > + .read = cros_ec_sync_id
> > + },
> > + {
> > + .name = "location",
> > + .read = cros_ec_sync_loc
> > + },
> > +};
> > +
> > +static int cros_ec_sensors_sync_probe(struct platform_device
> > *pdev)
> > +{
> > + struct cros_ec_sensors_sync_state *state;
> > + struct device *dev = &pdev->dev;
> > + struct iio_chan_spec *channel;
> > + struct iio_dev *indio_dev;
> > + int ret;
> > +
> > + indio_dev = devm_iio_device_alloc(dev, sizeof(*state));
> > + if (!indio_dev)
> > + return -ENOMEM;
> > +
> > + ret = cros_ec_sensors_core_init(pdev, indio_dev, true);
> > + if (ret)
> > + return ret;
> > +
> > + indio_dev->info = &cros_ec_sensors_sync_info;
> > + state = iio_priv(indio_dev);
> > +
> > + if (state->core.type != MOTIONSENSE_TYPE_SYNC)
> > + return -EINVAL;
> > +
> > + /* Initialize IIO device */
> > + channel = state->channels;
> > + channel->type = IIO_TIMESTAMP;
> > + channel->channel = -1;
> > + channel->scan_index = 1;
> > + channel->scan_type.sign = 's';
> > + channel->scan_type.realbits = 64;
> > + channel->scan_type.storagebits = 64;
> > +
> > + indio_dev->channels = state->channels;
> > + indio_dev->num_channels = MAX_CHANNELS;
> > +
> > + 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;
> > +
> > + ret = devm_iio_device_register(dev, indio_dev);
>
> Hmm. Wasn't expecting to see that here if it's a counter device.
>
>
> > + if (ret)
> > + return ret;
> > +
> > + /* Initialize counter device */
> > + state->counter.name = dev_name(&pdev->dev);
> > + state->counter.parent = &pdev->dev;
> > + state->counter.counts = &cros_ec_sync_counts;
> > + state->counter.num_counts = 1;
> > + state->counter.priv = indio_dev;
> > + state->counter.ops = &cros_ec_sync_cnt_ops;
> > + state->counter.ext = cros_ec_sync_cnt_ext;
> > + state->counter.num_ext = ARRAY_SIZE(cros_ec_sync_cnt_ext);
> > +
> > + return devm_counter_register(&pdev->dev, &state->counter);
> > +}
> > +
> > +static const struct platform_device_id cros_ec_sensors_sync_ids[]
> > = {
> > + { .name = DRV_NAME, },
> > + { }
> > +};
> > +MODULE_DEVICE_TABLE(platform, cros_ec_sensors_sync_ids);
> > +
> > +static struct platform_driver cros_ec_sensors_sync_platform_driver
> > = {
> > + .driver = {
> > + .name = DRV_NAME,
> > + .pm = &cros_ec_sensors_pm_ops,
> > + },
> > + .probe = cros_ec_sensors_sync_probe,
> > + .id_table = cros_ec_sensors_sync_ids,
> > +};
> > +module_platform_driver(cros_ec_sensors_sync_platform_driver);
> > +
> > +MODULE_DESCRIPTION("ChromeOS EC synchronisation sensor driver");
> > +MODULE_ALIAS("platform:" DRV_NAME);
> > +MODULE_LICENSE("GPL v2");
> > 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 805652250960..2bf183425eaf 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
> > @@ -22,6 +22,7 @@
> > static char *cros_ec_loc[] = {
> > [MOTIONSENSE_LOC_BASE] = "base",
> > [MOTIONSENSE_LOC_LID] = "lid",
> > + [MOTIONSENSE_LOC_CAMERA] = "camera",
> > [MOTIONSENSE_LOC_MAX] = "unknown",
> > };
> >
> > diff --git a/drivers/mfd/cros_ec_dev.c b/drivers/mfd/cros_ec_dev.c
> > index 41dccced5026..1c5c2c38af88 100644
> > --- a/drivers/mfd/cros_ec_dev.c
> > +++ b/drivers/mfd/cros_ec_dev.c
> > @@ -332,6 +332,9 @@ static void cros_ec_sensors_register(struct
> > cros_ec_dev *ec)
> > case MOTIONSENSE_TYPE_ACTIVITY:
> > sensor_cells[id].name = "cros-ec-activity";
> > break;
> > + case MOTIONSENSE_TYPE_SYNC:
> > + sensor_cells[id].name = "cros-ec-sync";
> > + break;
> > default:
> > dev_warn(ec->dev, "unknown type %d\n", resp-
> > >info.type);
> > continue;
> > diff --git a/include/linux/counter.h b/include/linux/counter.h
> > index a061cdcdef7c..1198e675306f 100644
> > --- a/include/linux/counter.h
> > +++ b/include/linux/counter.h
> > @@ -488,6 +488,7 @@ enum counter_signal_value_type {
> >
> > enum counter_count_value_type {
> > COUNTER_COUNT_POSITION = 0,
> > + COUNTER_COUNT_TALLY
> > };
> >
> > void counter_signal_read_value_set(struct
> > counter_signal_read_value *const val,