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

[Jonathan Cameron <jic23@kernel.org>]

On Mon, 19 Jul 2021 21:05:48 +0300
Andy Shevchenko <andy.shevchenko@gmail.com> 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.

I'm definitely keen to tidy this up, though I'd also rather not tie it
to this particular series.

> 
> Side note to Jonathan, I believe the below may be (lazily) converted
> to fwnode / device properties APIs.

Yup.  I know we still have a bunch of these to tidy up.
Might take a while to get to them though!

> 
> drivers/iio/adc/ab8500-gpadc.c:1041:    nchans =
> of_get_available_child_count(np);
> drivers/iio/adc/ad7124.c:747:   st->num_channels =
> of_get_available_child_count(np);
> drivers/iio/adc/berlin2-adc.c:287:      struct device_node *parent_np
> = of_get_parent(pdev->dev.of_node);
> drivers/iio/adc/qcom-pm8xxx-xoadc.c:830:        adc->nchans =
> of_get_available_child_count(np);
> drivers/iio/adc/qcom-spmi-adc5.c:650:   channel_name = of_get_property(node,
> drivers/iio/adc/qcom-spmi-adc5.c:813:   adc->nchannels =
> of_get_available_child_count(node);
> drivers/iio/adc/qcom-spmi-vadc.c:743:   vadc->nchannels =
> of_get_available_child_count(node);
> drivers/iio/adc/stm32-adc.c:1630:static int
> stm32_adc_of_get_resolution(struct iio_dev *indio_dev)
> drivers/iio/adc/stm32-adc.c:1935:       ret =
> stm32_adc_of_get_resolution(indio_dev);
> drivers/iio/adc/xilinx-xadc-core.c:1248:        chan_node =
> of_get_child_by_name(np, "xlnx,channels");
> drivers/iio/imu/adis16480.c:1293:static int
> adis16480_of_get_ext_clk_pin(struct adis16480 *st,
> drivers/iio/imu/adis16480.c:1328:       pin =
> adis16480_of_get_ext_clk_pin(st, of_node);
> drivers/iio/imu/inv_mpu6050/inv_mpu_i2c.c:68:           mux_node =
> of_get_child_by_name(dev->of_node, "i2c-gate")
> ;
> drivers/iio/industrialio-core.c:1877:   label =
> of_get_property(indio_dev->dev.of_node, "label", NULL);
> drivers/iio/inkern.c:228:               if (np && !of_get_property(np,
> "io-channel-ranges", NULL))
> drivers/iio/temperature/ltc2983.c:1275: st->num_channels =
> of_get_available_child_count(dev->of_node);
> 
>