Hi Jyoti
some minor things down below.
Other than that, FWIW about the SCMI side of this:
Reviewed-by: Cristian Marussi <cristian.marussi@xxxxxxx>
Thanks
Cristian
On Mon, Feb 08, 2021 at 09:19:18PM +0000, Jyoti Bhayana wrote:
> This change provides ARM SCMI Protocol based IIO device.
> This driver provides support for Accelerometer and Gyroscope using
> SCMI Sensor Protocol extensions added in the SCMIv3.0 ARM specification
>
> Signed-off-by: Jyoti Bhayana <jbhayana@xxxxxxxxxx>
> ---
> MAINTAINERS | 6 +
> drivers/firmware/arm_scmi/driver.c | 2 +-
> drivers/iio/common/Kconfig | 1 +
> drivers/iio/common/Makefile | 1 +
> drivers/iio/common/scmi_sensors/Kconfig | 18 +
> drivers/iio/common/scmi_sensors/Makefile | 5 +
> drivers/iio/common/scmi_sensors/scmi_iio.c | 673 +++++++++++++++++++++
> 7 files changed, 705 insertions(+), 1 deletion(-)
> create mode 100644 drivers/iio/common/scmi_sensors/Kconfig
> create mode 100644 drivers/iio/common/scmi_sensors/Makefile
> create mode 100644 drivers/iio/common/scmi_sensors/scmi_iio.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index b516bb34a8d5..ccf37d43ab41 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -8567,6 +8567,12 @@ S: Maintained
> F: Documentation/devicetree/bindings/iio/multiplexer/io-channel-mux.txt
> F: drivers/iio/multiplexer/iio-mux.c
>
> +IIO SCMI BASED DRIVER
> +M: Jyoti Bhayana <jbhayana@xxxxxxxxxx>
> +L: linux-iio@xxxxxxxxxxxxxxx
> +S: Maintained
> +F: drivers/iio/common/scmi_sensors/scmi_iio.c
> +
> IIO SUBSYSTEM AND DRIVERS
> M: Jonathan Cameron <jic23@xxxxxxxxxx>
> R: Lars-Peter Clausen <lars@xxxxxxxxxx>
> diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
> index 5392e1fc6b4e..248313bbd473 100644
> --- a/drivers/firmware/arm_scmi/driver.c
> +++ b/drivers/firmware/arm_scmi/driver.c
> @@ -741,7 +741,7 @@ static struct scmi_prot_devnames devnames[] = {
> { SCMI_PROTOCOL_SYSTEM, { "syspower" },},
> { SCMI_PROTOCOL_PERF, { "cpufreq" },},
> { SCMI_PROTOCOL_CLOCK, { "clocks" },},
> - { SCMI_PROTOCOL_SENSOR, { "hwmon" },},
> + { SCMI_PROTOCOL_SENSOR, { "hwmon", "iiodev" },},
> { SCMI_PROTOCOL_RESET, { "reset" },},
> { SCMI_PROTOCOL_VOLTAGE, { "regulator" },},
> };
> diff --git a/drivers/iio/common/Kconfig b/drivers/iio/common/Kconfig
> index 2b9ee9161abd..0334b4954773 100644
> --- a/drivers/iio/common/Kconfig
> +++ b/drivers/iio/common/Kconfig
> @@ -6,5 +6,6 @@
> source "drivers/iio/common/cros_ec_sensors/Kconfig"
> source "drivers/iio/common/hid-sensors/Kconfig"
> source "drivers/iio/common/ms_sensors/Kconfig"
> +source "drivers/iio/common/scmi_sensors/Kconfig"
> source "drivers/iio/common/ssp_sensors/Kconfig"
> source "drivers/iio/common/st_sensors/Kconfig"
> diff --git a/drivers/iio/common/Makefile b/drivers/iio/common/Makefile
> index 4bc30bb548e2..fad40e1e1718 100644
> --- a/drivers/iio/common/Makefile
> +++ b/drivers/iio/common/Makefile
> @@ -11,5 +11,6 @@
> obj-y += cros_ec_sensors/
> obj-y += hid-sensors/
> obj-y += ms_sensors/
> +obj-y += scmi_sensors/
> obj-y += ssp_sensors/
> obj-y += st_sensors/
> diff --git a/drivers/iio/common/scmi_sensors/Kconfig b/drivers/iio/common/scmi_sensors/Kconfig
> new file mode 100644
> index 000000000000..67e084cbb1ab
> --- /dev/null
> +++ b/drivers/iio/common/scmi_sensors/Kconfig
> @@ -0,0 +1,18 @@
> +#
> +# IIO over SCMI
> +#
> +# When adding new entries keep the list in alphabetical order
> +
> +menu "IIO SCMI Sensors"
> +
> +config IIO_SCMI
> + tristate "IIO SCMI"
> + depends on ARM_SCMI_PROTOCOL
> + select IIO_BUFFER
> + select IIO_KFIFO_BUF
> + help
> + Say yes here to build support for IIO SCMI Driver.
> + This provides ARM SCMI Protocol based IIO device.
> + This driver provides support for accelerometer and gyroscope
> + sensors available on SCMI based platforms.
> +endmenu
> diff --git a/drivers/iio/common/scmi_sensors/Makefile b/drivers/iio/common/scmi_sensors/Makefile
> new file mode 100644
> index 000000000000..f13140a2575a
> --- /dev/null
> +++ b/drivers/iio/common/scmi_sensors/Makefile
> @@ -0,0 +1,5 @@
> +# SPDX - License - Identifier : GPL - 2.0 - only
> +#
> +# Makefile for the IIO over SCMI
> +#
> +obj-$(CONFIG_IIO_SCMI) += scmi_iio.o
> diff --git a/drivers/iio/common/scmi_sensors/scmi_iio.c b/drivers/iio/common/scmi_sensors/scmi_iio.c
> new file mode 100644
> index 000000000000..093b1fc24e27
> --- /dev/null
> +++ b/drivers/iio/common/scmi_sensors/scmi_iio.c
> @@ -0,0 +1,673 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/*
> + * System Control and Management Interface(SCMI) based IIO sensor driver
> + *
> + * Copyright (C) 2021 Google LLC
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/kfifo_buf.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/kernel.h>
> +#include <linux/kthread.h>
> +#include <linux/module.h>
> +#include <linux/scmi_protocol.h>
> +#include <linux/time.h>
> +#include <linux/types.h>
> +
> +#define SCMI_IIO_NUM_OF_AXIS 3
> +
> +struct scmi_iio_priv {
> + struct scmi_handle *handle;
> + const struct scmi_sensor_info *sensor_info;
> + struct iio_dev *indio_dev;
> + /* adding one additional channel for timestamp */
> + long long iio_buf[SCMI_IIO_NUM_OF_AXIS + 1];
> + struct notifier_block sensor_update_nb;
> + u32 *freq_avail;
> +};
> +
> +static int scmi_iio_sensor_update_cb(struct notifier_block *nb,
> + unsigned long event, void *data)
> +{
> + struct scmi_sensor_update_report *sensor_update = data;
> + struct iio_dev *scmi_iio_dev;
> + struct scmi_iio_priv *sensor;
> + s8 tstamp_scale;
> + u64 time, time_ns;
> + int i;
> +
> + if (sensor_update->readings_count == 0)
> + return NOTIFY_DONE;
> +
> + sensor = container_of(nb, struct scmi_iio_priv, sensor_update_nb);
> +
> + for (i = 0; i < sensor_update->readings_count; i++)
> + sensor->iio_buf[i] = sensor_update->readings[i].value;
> +
> + if (!sensor->sensor_info->timestamped) {
> + time_ns = ktime_to_ns(sensor_update->timestamp);
> + } else {
> + /*
> + * All the axes are supposed to have the same value for timestamp.
> + * We are just using the values from the Axis 0 here.
> + */
> + time = sensor_update->readings[0].timestamp;
> +
> + /*
> + * Timestamp returned by SCMI is in seconds and is equal to
> + * time * power-of-10 multiplier(tstamp_scale) seconds.
> + * Converting the timestamp to nanoseconds below.
> + */
> + tstamp_scale = sensor->sensor_info->tstamp_scale +
> + const_ilog2(NSEC_PER_SEC) / const_ilog2(10);
> + if (tstamp_scale < 0)
> + time_ns =
> + div64_u64(time, int_pow(10, abs(tstamp_scale)));
> + else
> + time_ns = time * int_pow(10, tstamp_scale);
> + }
> +
> + scmi_iio_dev = sensor->indio_dev;
> + iio_push_to_buffers_with_timestamp(scmi_iio_dev, sensor->iio_buf,
> + time_ns);
> + return NOTIFY_OK;
> +}
> +
> +static int scmi_iio_buffer_preenable(struct iio_dev *iio_dev)
> +{
> + struct scmi_iio_priv *sensor = iio_priv(iio_dev);
> + u32 sensor_id = sensor->sensor_info->id;
> + u32 sensor_config = 0;
> + int err;
> +
> + if (sensor->sensor_info->timestamped)
> + sensor_config |= FIELD_PREP(SCMI_SENS_CFG_TSTAMP_ENABLED_MASK,
> + SCMI_SENS_CFG_TSTAMP_ENABLE);
> +
> + sensor_config |= FIELD_PREP(SCMI_SENS_CFG_SENSOR_ENABLED_MASK,
> + SCMI_SENS_CFG_SENSOR_ENABLE);
> +
> + err = sensor->handle->notify_ops->register_event_notifier(sensor->handle,
> + SCMI_PROTOCOL_SENSOR, SCMI_EVENT_SENSOR_UPDATE,
> + &sensor_id, &sensor->sensor_update_nb);
> + if (err) {
> + dev_err(&iio_dev->dev,
> + "Error in registering sensor update notifier for sensor %s err %d",
> + sensor->sensor_info->name, err);
> + return err;
> + }
> +
> + err = sensor->handle->sensor_ops->config_set(sensor->handle,
> + sensor->sensor_info->id, sensor_config);
> + if (err) {
> + sensor->handle->notify_ops->unregister_event_notifier(sensor->handle,
> + SCMI_PROTOCOL_SENSOR,
> + SCMI_EVENT_SENSOR_UPDATE, &sensor_id,
> + &sensor->sensor_update_nb);
> + dev_err(&iio_dev->dev, "Error in enabling sensor %s err %d",
> + sensor->sensor_info->name, err);
> + }
> +
> + return err;
> +}
> +
> +static int scmi_iio_buffer_postdisable(struct iio_dev *iio_dev)
> +{
> + struct scmi_iio_priv *sensor = iio_priv(iio_dev);
> + u32 sensor_id = sensor->sensor_info->id;
> + u32 sensor_config = 0;
> + int err;
> +
> + sensor_config |= FIELD_PREP(SCMI_SENS_CFG_SENSOR_ENABLED_MASK,
> + SCMI_SENS_CFG_SENSOR_DISABLE);
> +
> + err = sensor->handle->notify_ops->unregister_event_notifier(sensor->handle,
> + SCMI_PROTOCOL_SENSOR, SCMI_EVENT_SENSOR_UPDATE,
> + &sensor_id, &sensor->sensor_update_nb);
> + if (err) {
> + dev_err(&iio_dev->dev,
> + "Error in unregistering sensor update notifier for sensor %s err %d",
> + sensor->sensor_info->name, err);
> + return err;
> + }
> +
> + err = sensor->handle->sensor_ops->config_set(sensor->handle, sensor_id,
> + sensor_config);
> + if (err) {
> + dev_err(&iio_dev->dev,
> + "Error in disabling sensor %s with err %d",
> + sensor->sensor_info->name, err);
> + }
> +
> + return err;
> +}
> +
> +static const struct iio_buffer_setup_ops scmi_iio_buffer_ops = {
> + .preenable = scmi_iio_buffer_preenable,
> + .postdisable = scmi_iio_buffer_postdisable,
> +};
This is just a question, I'm not suggesting to change anything here at
this point to be clear, since it works just fine as it is.
Following up a previous email, given these are called on enable/disable
by sysfs, is there a specific reason why you configure here, inside
these ops, also timestamping and callbacks i.e. each time the sensor is
turned on/off by sysfs ? ... instead of just, as an example, enabling
in _preenable the sensor while registering callbacks and enabling
timestamping once for all earlier during probe phase ?
(likewise for _postdisable -> remove)
AFAIU the spec says notifications are emitted for sensors which has
requested them (via SENSOR_CONTINUOUS_UPDATE_NOTIFY) BUT only if the
sensor is enabled as a whole (via proper CONFIG_SET as you do), so
that enabling/disabling the sensor as a whole should result in starting/
stopping the notification flow without the need of unregistering the
callbacks everytime. (same goes with the timestamping)
In other words, I would expect the sensor to maintain its state (on the
platform side) even when going through enable/disable cycles, so that
it 'remembers' that timestamping/notifications were enabled across an
on/off.
This would reduce the number of SCMI messages exchanges between the
kernel and the platform and should be supported by both, but as said,
it's more of a question for the future, not necessarily for this series.
> +
[snip]
> +static int scmi_iio_set_sampling_freq_avail(struct iio_dev *iio_dev)
> +{
> + u64 cur_interval_ns, low_interval_ns, high_interval_ns, step_size_ns,
> + hz, uhz;
> + unsigned int cur_interval, low_interval, high_interval, step_size;
> + struct scmi_iio_priv *sensor = iio_priv(iio_dev);
> + int i;
> +
> + sensor->freq_avail =
> + devm_kzalloc(&iio_dev->dev,
> + sizeof(*sensor->freq_avail) *
> + (sensor->sensor_info->intervals.count * 2),
> + GFP_KERNEL);
> + if (!sensor->freq_avail)
> + return -ENOMEM;
> +
> + if (sensor->sensor_info->intervals.segmented) {
> + low_interval = sensor->sensor_info->intervals
> + .desc[SCMI_SENS_INTVL_SEGMENT_LOW];
> + low_interval_ns = scmi_iio_convert_interval_to_ns(low_interval);
> + convert_ns_to_freq(low_interval_ns, &hz, &uhz);
> + sensor->freq_avail[0] = hz;
> + sensor->freq_avail[1] = uhz;
> +
> + step_size = sensor->sensor_info->intervals
> + .desc[SCMI_SENS_INTVL_SEGMENT_STEP];
> + step_size_ns = scmi_iio_convert_interval_to_ns(step_size);
> + convert_ns_to_freq(step_size_ns, &hz, &uhz);
> + sensor->freq_avail[2] = hz;
> + sensor->freq_avail[3] = uhz;
> +
> + high_interval = sensor->sensor_info->intervals
> + .desc[SCMI_SENS_INTVL_SEGMENT_HIGH];
> + high_interval_ns =
> + scmi_iio_convert_interval_to_ns(high_interval);
> + convert_ns_to_freq(high_interval_ns, &hz, &uhz);
> + sensor->freq_avail[4] = hz;
> + sensor->freq_avail[5] = uhz;
> + } else {
> + for (i = 0; i < sensor->sensor_info->intervals.count; i++) {
> + cur_interval = sensor->sensor_info->intervals.desc[i];
> + cur_interval_ns =
> + scmi_iio_convert_interval_to_ns(cur_interval);
> + convert_ns_to_freq(cur_interval_ns, &hz, &uhz);
> + sensor->freq_avail[i * 2] = hz;
> + sensor->freq_avail[i * 2 + 1] = uhz;
> + }
> + }
> + return 0;
> +}
> +
> +static int scmi_iio_buffers_setup(struct iio_dev *scmi_iiodev)
> +{
> + struct iio_buffer *buffer;
> +
> + buffer = devm_iio_kfifo_allocate(&scmi_iiodev->dev);
> + if (!buffer)
> + return -ENOMEM;
> +
> + iio_device_attach_buffer(scmi_iiodev, buffer);
> + scmi_iiodev->modes |= INDIO_BUFFER_SOFTWARE;
> + scmi_iiodev->setup_ops = &scmi_iio_buffer_ops;
> + return 0;
> +}
> +
> +struct iio_dev *scmi_alloc_iiodev(struct device *dev,
> + struct scmi_handle *handle,
> + const struct scmi_sensor_info *sensor_info)
> +{
> + struct iio_chan_spec *iio_channels;
> + struct scmi_iio_priv *sensor;
> + enum iio_modifier modifier;
> + enum iio_chan_type type;
> + struct iio_dev *iiodev;
> + int i, ret;
> +
> + iiodev = devm_iio_device_alloc(dev, sizeof(*sensor));
> + if (!iiodev)
> + return ERR_PTR(-ENOMEM);
> +
> + iiodev->modes = INDIO_DIRECT_MODE;
> + iiodev->dev.parent = dev;
> + sensor = iio_priv(iiodev);
> + sensor->handle = handle;
> + sensor->sensor_info = sensor_info;
> + sensor->sensor_update_nb.notifier_call = scmi_iio_sensor_update_cb;
> + sensor->indio_dev = iiodev;
> +
> + /* adding one additional channel for timestamp */
> + iiodev->num_channels = sensor_info->num_axis + 1;
> + iiodev->name = sensor_info->name;
> + iiodev->info = &scmi_iio_info;
> +
> + iio_channels =
> + devm_kzalloc(dev,
> + sizeof(*iio_channels) * (iiodev->num_channels),
> + GFP_KERNEL);
> + if (!iio_channels)
> + return ERR_PTR(-ENOMEM);
> +
> + scmi_iio_set_sampling_freq_avail(iiodev);
You don't check this for retval, and it could fail with -ENOMEM.
> +
> + for (i = 0; i < sensor_info->num_axis; i++) {
> + ret = scmi_iio_get_chan_type(sensor_info->axis[i].type, &type);
> + if (ret < 0)
> + return ERR_PTR(ret);
> +
> + ret = scmi_iio_get_chan_modifier(sensor_info->axis[i].name,
> + &modifier);
> + if (ret < 0)
> + return ERR_PTR(ret);
> +
> + scmi_iio_set_data_channel(&iio_channels[i], type, modifier,
> + sensor_info->axis[i].id);
> + }
> +
> + scmi_iio_set_timestamp_channel(&iio_channels[i], i);
> + iiodev->channels = iio_channels;
> + return iiodev;
> +}
> +
