Re: [PATCH v5 1/1] iio/scmi: Adding support for IIO SCMI Based Sensors

From: Jonathan Cameron
Date: Tue Feb 16 2021 - 15:06:42 EST

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In reply to: Cristian Marussi: "Re: [PATCH v5 1/1] iio/scmi: Adding support for IIO SCMI Based Sensors"
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On Tue, 16 Feb 2021 10:20:59 +0000
Cristian Marussi <cristian.marussi@xxxxxxx> wrote:

> Hi Jyoti,
>
> On Mon, Feb 15, 2021 at 04:14:57PM -0800, Jyoti Bhayana wrote:
> > Hi Jonathan/Cristian,
> >
> > I have uploaded v6 of the IIO SCMI patch. Not sure if you got a chance to
> > review that version and if any further changes are needed.
>
> Seen that, for the SCMI part seemed fine to me, I'll just have still to
> reply.

I'll confess I'm not rushing reviewing this, simply because it's
proved complex / unusual enough that I want to have another hard look at it
+ we have a bit of time now. I can't fall back on semi conscious reviewing
for this one ;)

Apologies for the delay in the meantime!

Jonathan

>
> > My IIO SCMI patch is independent of Cristian series mentioned at
> > https://lore.kernel.org/linux-arm-kernel/20210202221555.41167-1-cristian.marussi@xxxxxxx/
> > right?
>
> Yes, that's true, your patch is independent and goes in as it is now, and I'll
> rebase my series on yours on a dedicated branch and make all the needed
> (small) interface changes.
>
> > and it can be merged without the Cristian Series right? Are there plans to
> > merge my v6 of the IIO SCMI patch and Cristian latest series in the same
> > linux tree version?
>
> Yes absolutely, your driver can be merged as it is without my series, but due
> to the timing they ended up targeting the same Linux version 5.13 at the
> end, so they will be merged both in v5.13, yours first as it is now, mine
> immediately rebased on top of it aftewards: the end result will be both
> series in the same v5.13 but as distinct patches. (so you can still backport
> yours on v5.4 as you're doing now.)
>
> Thanks
>
> Cristian
>
> >
> > Thanks,
> > Jyoti
> >
> > On Mon, Feb 15, 2021 at 6:48 AM Cristian Marussi <cristian.marussi@xxxxxxx>
> > wrote:
> >
> > > On Mon, Feb 15, 2021 at 11:07:56AM +0000, Jonathan Cameron wrote:
> > > > On Mon, 15 Feb 2021 09:25:26 +0000
> > > > Cristian Marussi <cristian.marussi@xxxxxxx> wrote:
> > > >
> > > > > On Fri, Feb 12, 2021 at 07:18:58PM +0000, Jonathan Cameron wrote:
> > > > > > On Wed, 10 Feb 2021 21:46:19 +0000
> > > > > > Cristian Marussi <cristian.marussi@xxxxxxx> wrote:
> > > > > >
> > > > > > > Hi Jyoti,
> > > > > > >
> > > > > > > On Wed, Feb 10, 2021 at 11:19:35AM -0800, Jyoti Bhayana wrote:
> > > > > > > > Hi Cristian,
> > > > > > > >
> > > > > > > > Thanks for the feedback. Regarding registering callbacks at the
> > > probe time
> > > > > > > > instead of .preenable, I have tried it before but I think due to
> > > some
> > > > > > > > issues(don't remember it now maybe on the platform side) I kept
> > > it at the
> > > > > > > > .preenable level.
> > > > > > > >
> > > > > > > > But you are right, that it will be nice to move it at the probe
> > > level
> > > > > > > > instead. I will try again and test if it works and would move it
> > > at the
> > > > > > > > probe level. Regarding the unregistering of the notifier, is it
> > > required at
> > > > > > > > the remove of iio driver or scmi driver will take care of it?
> > > > > > > > Because if I add unregister at the iio driver remove level, I
> > > would have to
> > > > > > > > iterate all the sensors again and unregister them.
> > > > > > >
> > > > > > > Yes you are right if you move callbacks registration once for all
> > > to the
> > > > > > > .probe step you'll have to unregister them all in a .remove.
> > > > > > >
> > > > > > > BUT I think instead you should stick with your current solution
> > > given
> > > > > > > it's working fine anyway and it's supported by the notification
> > > > > > > framework and also for another reason I'm going to explain down
> > > below
> > > > > > > (which is also the reason why I asked you this at first :D)
> > > > > > >
> > > > > > > As you may remember I'm refactoring all the SCMI internals in a
> > > separate
> > > > > > > series to ease modularization and vendor protocols support, and
> > > that will
> > > > > > > lead also to some changes in the SCMI driver interface that you
> > > use:
> > > > > > > amongst other things one interesting addition will be a new devres
> > > managed
> > > > > > > notification registration method, something like:
> > > > > > >
> > > > > > > handle->notify_ops->devm_register_notifier(sdev, ...);
> > > > > > >
> > > > > > > With such method you could just move your registration to the
> > > .probe
> > > > > > > step and just forget about it, without the need to add any
> > > unregistration
> > > > > > > in the .remove step, since the core will take care to remove all
> > > the
> > > > > > > callbacks at driver unloading time.
> > > > > > >
> > > > > > > Now, this series, which is here if you want to have a look:
> > > > > > >
> > > > > > >
> > > https://lore.kernel.org/linux-arm-kernel/20210202221555.41167-1-cristian.marussi@xxxxxxx/
> > > > > > >
> > > > > > > is already taking care to port any existent SCMI driver to the new
> > > interface,
> > > > > > > so when your IIODEV SCMI driver will be finally queued somewhere
> > > for merge, I
> > > > > > > can in turn rebase my series on yours and take care to port your
> > > driver too to
> > > > > > > the new interface applying the changes above in the context of my
> > > series.
> > > > > > > (and ask you to review of course :D)
> > > > > >
> > > > > > I'm guessing you probably want this driver in an immutable branch
> > > then
> > > > > > rather than having to wait another cycle for it to tick through to a
> > > > > > a sensible upstream?
> > > > > >
> > > > >
> > > > > Hi Jonathan
> > > > >
> > > > > the above series (still pending a final review from Sudeep) is targeted
> > > > > at 5.13 at this point and usually it'd be queued via Sudeep
> > > for-next/scmi
> > > > > which in turn goes via the ARM soc branch.
> > > > >
> > > > > Having said that, I'm not really familiar enough with this sort of
> > > clashes
> > > > > to know how they should be properly handled, so I'll stick to what you
> > > > > and Sudeep would think it's better :D (..and I'm pinging him to have a
> > > say)
> > > > >
> > > > > Thanks
> > > > >
> > > > > Cristian
> > > > Hi Cristian,
> > > >
> > > > So this driver will also be 5.13 material now (merge window for IIO
> > > effectively
> > > > closes 1-2 weeks before Linus opens the main one).
> > > >
> > > > The way we normally handle cases like this where we likely to have
> > > dependencies
> > > > on a patch set from two separate directions is to do what is known as an
> > > > immutable branch. This is a branch that would probably be based on
> > > 5.12-rc1
> > > > containing just this driver.
> > > >
> > > > Then both trees, in this case IIO and scmi merge that branch. The magic
> > > > of git then means that when Linus gets the eventual pull requests for
> > > > the two trees, the git IDs and content will be the same and the history
> > > > of that particular set of files will be cleanly maintained.
> > > >
> > > > This happens quite a lot for certain parts of the kernel because there
> > > are
> > > > a lot of cross dependencies.
> > > >
> > > Hi Jonathan
> > >
> > > thanks for clarifying.
> > >
> > > Cristian
> > >
> > > > @Sudeep, that work for you? Have to wait for 5.12-rc1 though to give
> > > > us a sensible base.
> > > >
> > > > Jonathan
> > > >
> > > > >
> > > > > > Jonathan
> > > > > >
> > > > > > >
> > > > > > > I'm saying that is better if you keep your series as it is for now
> > > > > > > (old interface + .preenable/.postdisable regs/unregs) because, as
> > > said,
> > > > > > > with the new interface the devm_ methods will ease the registration
> > > > > > > @probe time, and also especially because the new interface is not
> > > (and
> > > > > > > most probably won't) be part of the v5.4 backport that you are
> > > testing
> > > > > > > against: so if you stick with your current solution you'll have a
> > > > > > > working patch easily backportable now, and once queued I'll port
> > > it to
> > > > > > > the interface using devm_ (so simplifying it)
> > > > > > >
> > > > > > > In this context, it would be indeed important to know if in
> > > general moving
> > > > > > > registration to the probe phase (which should be fine by the spec)
> > > poses
> > > > > > > any kind of problem. (and that's reason why asked it)
> > > > > > >
> > > > > > > Hope to have been clear despite the flood of words :D
> > > > > > >
> > > > > > > Thanks
> > > > > > >
> > > > > > > Cristian
> > > > > > >
> > > > > > > >
> > > > > > > > Thanks,
> > > > > > > > Jyoti
> > > > > > > >
> > > > > > > > On Tue, Feb 9, 2021 at 3:56 AM Cristian Marussi <
> > > cristian.marussi@xxxxxxx>
> > > > > > > > wrote:
> > > > > > > >
> > > > > > > > > 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;
> > > > > > > > > > +}
> > > > > > > > > > +
> > > > > > > > >
> > > > > >
> > > >
> > >

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