Re: [PATCH v9 4/5] iio: adc: versal-sysmon: add threshold event support

[Erim, Salih]

Hi Andy,

On 18/06/2026 08:09, Andy Shevchenko wrote:
> On Wed, Jun 17, 2026 at 07:01:46PM +0100, Salih Erim wrote:
> > Add threshold event support for temperature and supply voltage
> > channels.
> >
> > Temperature events:
> >    - Rising threshold with configurable value on the device
> >      temperature channel (current max across all satellites)
> >    - Per-channel hysteresis as a millicelsius value
> >    - Event direction is IIO_EV_DIR_RISING (hysteresis mode)
> >
> > Supply voltage events:
> >    - Rising/falling threshold per supply channel
> >    - Per-channel alarm enable via alarm configuration registers
> >
> > The hardware supports both window and hysteresis alarm modes for
> > temperature. This driver uses hysteresis mode, where the upper
> > threshold triggers the alarm and the lower threshold clears it
> > (re-arm point). The hardware has a single ISR bit per temperature
> > channel with no indication of which threshold was crossed, so
> > hysteresis mode is the natural fit. The lower threshold register
> > is computed internally as (upper - hysteresis).
> >
> > Hysteresis is stored in the driver as a millicelsius value,
> > initialized from the hardware registers at probe. Writing the
> > rising threshold or hysteresis recomputes the lower register.
> > ALARM_CONFIG is hard-coded to hysteresis mode during init.
> >
> > The hardware also provides a separate over-temperature (OT)
> > threshold, but it is not exposed through IIO as it serves as a
> > hardware safety mechanism for platform shutdown. OT will be
> > exposed through the thermal framework in a follow-up series.
> >
> > The interrupt handler masks active threshold interrupts (which are
> > level-sensitive) and schedules a delayed worker to poll for condition
> > clear before unmasking. When no hardware IRQ is available, event
> > specs are not attached and interrupt init is skipped, since the
> > I2C regmap backend cannot be called from atomic context.
> >
> > When disabling a supply channel alarm, the group interrupt remains
> > active if any other channel in the same alarm group still has an
> > alarm enabled.
> >
> > A devm cleanup action masks all interrupts on driver unbind to
> > prevent unhandled interrupt storms after the IRQ handler is freed.
>
> A couple of nit-picks below, otherwise
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxx>

Thank you for the review!

> ...
>
> >   #include <linux/cleanup.h>
> >   #include <linux/device.h>
> >   #include <linux/err.h>
> > +#include <linux/interrupt.h>
>
> + limits.h // U16_MAX, et cetera

Will add.
> > +#include <linux/minmax.h>
> >   #include <linux/module.h>
> >   #include <linux/overflow.h>
> >   #include <linux/property.h>
>
> ...
>
> > -static int sysmon_parse_fw(struct iio_dev *indio_dev, struct device *dev)
> > +static int sysmon_parse_fw(struct iio_dev *indio_dev, struct device *dev, int irq)
> >   {
> >        unsigned int num_chan, num_static, idx, temp_chan_idx, volt_chan_idx;
> > -     unsigned int num_supply, num_temp;
> >        struct iio_chan_spec *sysmon_channels;
> > +     unsigned int num_supply, num_temp;
>
> Stray change, and I would expect to see all num_* on one line, and
> all *_idx on another.
>
>          unsigned int num_chan, num_static, num_supply, num_temp;
>          unsigned int idx, temp_chan_idx, volt_chan_idx;
>          struct iio_chan_spec *sysmon_channels;
>
> TL;DR:
> in this patch the above should not be modified as the previous one should
> provide already a nice structure.

Accepted. Will restructure in P2 so P4 inherits cleanly.

Thanks,
Salih

> >        const char *label;
> >        u32 reg;
> >        int ret;
>
> --
> With Best Regards,
> Andy Shevchenko