Re: [PATCH 3/4] iio: accel: bmc150: Make it possible to configure INT2 instead of INT1

[Stephan Gerhold <stephan@gerhold.net>]

On Mon, Jul 19, 2021 at 09:05:48PM +0300, Andy Shevchenko wrote:
> On Mon, Jul 19, 2021 at 8:29 PM Stephan Gerhold <stephan@gerhold.net> wrote:
> >
> > On Mon, Jul 19, 2021 at 07:19:05PM +0300, Andy Shevchenko wrote:
> > > On Mon, Jul 19, 2021 at 6:11 PM Stephan Gerhold <stephan@gerhold.net> wrote:
> > > > On Mon, Jul 19, 2021 at 06:01:01PM +0300, Andy Shevchenko wrote:
> > > > > On Mon, Jul 19, 2021 at 5:07 PM Linus Walleij <linus.walleij@linaro.org> wrote:
> > > > > > On Mon, Jul 19, 2021 at 1:26 PM Stephan Gerhold <stephan@gerhold.net> wrote:
> 
> ...
> 
> > > > > > >  #include <linux/acpi.h>
> > > > > > > +#include <linux/of_irq.h>
> > > > > > (...)
> > > > > > > +       irq_info = bmc150_accel_interrupts_int1;
> > > > > > > +       if (irq == of_irq_get_byname(dev->of_node, "INT2"))
> > > > > > > +               irq_info = bmc150_accel_interrupts_int2;
> > > > > >
> > > > > > This looks a bit DT-specific, but I don't see that ACPI has
> > > > > > named IRQs so I don't know what to do about it either.
> > > > >
> > > > > Yeah, we only have so far the (de facto) established way of naming
> > > > > GPIO based IRQs, and not IOxAPIC ones.
> > > > >
> > > > > > What does platform_get_irq_byname() do on ACPI systems?
> > > > >
> > > > > See above.
> > > > >
> > > > > > If there is no obvious fix I would leave it like this until the
> > > > > > first ACPI used needing this comes along, but I think maybe
> > > > > > Andy has suggestions.
> > > > >
> > > > > The platform_get_irq_byname() should do something similar that has
> > > > > been done in platform_get_irq() WRT ACPI.
> > > > > Here for sure the platform_get_irq_byname() or its optional variant
> > > > > should be used.
> > > >
> > > > I don't think there is a platform device here, we only have the
> > > > i2c_client or spi_device. That's why I didn't use
> > > > platform_get_irq_byname(). :)
> > > >
> > > > Is there something equivalent for I2C/SPI drivers?
> > >
> > > Not yet. You probably need to supply some code there to allow
> > > multi-IRQ devices (in resource provider agnostic way).
> > >
> > > You need to provide fwnode_get_irq_byname() to be similar with
> > > https://elixir.bootlin.com/linux/latest/source/drivers/base/property.c#L1010
> > >
> > > Then use it in the drivers.
> > >
> > > And/or integrate into frameworks somehow (something in between the
> > > lines: https://elixir.bootlin.com/linux/latest/source/drivers/i2c/i2c-core-base.c#L461).
> > >
> >
> > Well, I don't think anyone has an ACPI use case for this right now so
> > it's probably better if this is done by someone who actually needs this
> > and can test it somewhere. :)
> >
> > I actually just "copied" this approach from some other IIO drivers where
> > this is done similarly (and additionally checked the source code to make
> > sure this won't break anything for ACPI platforms).
> 
> I see in today's Linux Next snapshot:
> 
> drivers/iio/accel/fxls8962af-core.c:774:        irq =
> of_irq_get_byname(of_node, "INT2");
> drivers/iio/accel/mma8452.c:1616:               irq2 =
> of_irq_get_byname(client->dev.of_node, "INT2");
> drivers/iio/gyro/fxas21002c_core.c:834: irq1 = of_irq_get_byname(np, "INT1");
> drivers/iio/imu/adis16480.c:1265:               irq =
> of_irq_get_byname(of_node, adis16480_int_pin_names[i]);
> drivers/iio/imu/bmi160/bmi160_core.c:655:       irq =
> of_irq_get_byname(of_node, "INT1");
> drivers/iio/imu/bmi160/bmi160_core.c:661:       irq =
> of_irq_get_byname(of_node, "INT2");
> 
> I believe we may stop distributing this and actually start using a
> common API. I don't want this to be spread again over all IIO. Btw, I
> have LSM9DS0, which supports two INT pins for IMU and currently it
> uses hard coded pin mapping.
> 

Hm, I'm not quite sure how to implement this. Could you prepare a patch
that would implement such a common API? I would be happy to test it for
the device tree and make use of it in this patch.

To be honest, I mainly implemented support for the interrupt-names
because Jonathan mentioned this would be nice to have [1] and it kind of
fit well together with the BMC156 patch that needs the INT2 support.
I actually just use the if (data->type == BOSCH_BMC156) part from
PATCH 4/4 which does not depend on of_irq_get_byname().

Thanks,
Stephan

[1]: https://lore.kernel.org/linux-iio/20210611185941.3487efc6@jic23-huawei/