Re: [PATCH 2/3] iio: adc: ad7887: convert driver to full DT probing

Alexandru Ardelean
2020-11-18T13:00:13Z

On Tue, Nov 17, 2020 at 6:02 PM Jonathan Cameron
<Jonathan.Cameron@huawei.com> wrote:
>
> On Tue, 17 Nov 2020 17:03:06 +0200
> Alexandru Ardelean <ardeleanalex@gmail.com> wrote:
>
> > On Tue, Nov 17, 2020 at 1:06 PM Jonathan Cameron
> > <Jonathan.Cameron@huawei.com> wrote:
> > >
> > > On Tue, 17 Nov 2020 11:01:11 +0000
> > > Jonathan Cameron <Jonathan.Cameron@Huawei.com> wrote:
> > >
> > > > On Tue, 17 Nov 2020 09:52:53 +0200
> > > > Alexandru Ardelean <alexandru.ardelean@analog.com> wrote:
> > > >
> > > > > This change removes the SPI device table, adds an OF device table instead.
> > > > > This should also be usable for ACPI via PRP0001.
> > > > >
> > > > > This device is usually probed via device-tree, so it makes more sense to
> > > > > use the OF device table.
> > > > >
> > > > > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
> > > > So, we've had a few cases of having to put the device_id table
> > > > back again recently.
> > > > https://lore.kernel.org/linux-iio/20201101152613.2c37581a@archlinux/
> > > >
> > > > They tend to be due to greybus doing it's probing in yet another fashion.
> > > > So far they've been all i2c devices, but I kind of assume it does the same for spi.
> > > > https://elixir.bootlin.com/linux/latest/source/drivers/staging/greybus/spilib.c#L437
> > > >
> > > > How device_get_match_data() plays with that I'm not sure. It probably
> > > > doesn't right now given swnode doesn't have a device_get_match_data() callback.
> > > >
> > > > https://elixir.bootlin.com/linux/latest/source/drivers/base/swnode.c#L539
> > > >
> > > > So after all that I think I've argued myself around to thinking what you have
> > > > here is fine. If someone wants to support this via a swnode then they can
> > > > figure out how to make that work.
> > > >
> > > > +CC Vaishnav and Andy for their input.
> > > >
> > > > Otherwise looks fine to me.
> > >
> > > Having said that.... Why are we going through this dance for driver with
> > > only one compatible? Are there other parts on their way?
> > > If not, perhaps we should just rip out the matching code entirely in
> > > the interests of simplicity.
> >
> > So, this one has a bit of a funny story.
> > There's an AD7888 which is similar in terms of registers but with more channels.
> > Lars did a patch to support it on top of AD7887:
> > https://github.com/analogdevicesinc/linux/commits/iio-ad7888
> >
> > We tried to order a part for this to test the changes, but we got a
> > reply that it's obsolete.
> > The website says it is still in production.
> > So, I was confused about the answer we got. ¯\_(ツ)_/¯
> >
> > In the meantime, I thought I'd take some of the cleanup value of Lars'
> > work and do the cleanup only.
> > We may still find that part somewhere and maybe add it, or maybe
> > another one would come along.
> > I don't know at this point. I'm mostly looking at some of my backlog
> > stuff and trying to cleanup old stuff.
> >
> > I'm fine to simplify the driver now and add the matching bits later.
>
> Sounds good to me.

I'm a bit vague on the message of this reply.
Should I simplify it or leave it as-is?

>
> >
> > >
> > > Jonathan
> > >
> > > >
> > > > Thanks,
> > > >
> > > > Jonathan
> > > >
> > > >
> > > > > ---
> > > > > drivers/iio/adc/ad7887.c | 23 +++++++++++++++--------
> > > > > 1 file changed, 15 insertions(+), 8 deletions(-)
> > > > >
> > > > > diff --git a/drivers/iio/adc/ad7887.c b/drivers/iio/adc/ad7887.c
> > > > > index 06f684c053a0..4f68a1b17ec8 100644
> > > > > --- a/drivers/iio/adc/ad7887.c
> > > > > +++ b/drivers/iio/adc/ad7887.c
> > > > > @@ -40,6 +40,7 @@ enum ad7887_channels {
> > > > >
> > > > > /**
> > > > > * struct ad7887_chip_info - chip specifc information
> > > > > + * @name: the name of the part
> > > > > * @int_vref_mv: the internal reference voltage
> > > > > * @channels: channels specification
> > > > > * @num_channels: number of channels
> > > > > @@ -47,6 +48,7 @@ enum ad7887_channels {
> > > > > * @num_dual_channels: number of channels in dual mode
> > > > > */
> > > > > struct ad7887_chip_info {
> > > > > + const char *name;
> > > > > u16 int_vref_mv;
> > > > > const struct iio_chan_spec *channels;
> > > > > unsigned int num_channels;
> > > > > @@ -218,6 +220,7 @@ static const struct ad7887_chip_info ad7887_chip_info_tbl[] = {
> > > > > * More devices added in future
> > > > > */
> > > > > [ID_AD7887] = {
> > > > > + .name = "ad7887",
> > > > > .channels = ad7887_channels,
> > > > > .num_channels = ARRAY_SIZE(ad7887_channels),
> > > > > .dual_channels = ad7887_dual_channels,
> > > > > @@ -239,12 +242,17 @@ static void ad7887_reg_disable(void *data)
> > > > >
> > > > > static int ad7887_probe(struct spi_device *spi)
> > > > > {
> > > > > + const struct ad7887_chip_info *info;
> > > > > struct ad7887_state *st;
> > > > > struct iio_dev *indio_dev;
> > > > > bool dual_mode;
> > > > > uint8_t mode;
> > > > > int ret;
> > > > >
> > > > > + info = device_get_match_data(&spi->dev);
> > > > > + if (!info)
> > > > > + return -ENODEV;
> > > > > +
> > > > > indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> > > > > if (indio_dev == NULL)
> > > > > return -ENOMEM;
> > > > > @@ -269,13 +277,12 @@ static int ad7887_probe(struct spi_device *spi)
> > > > > return ret;
> > > > > }
> > > > >
> > > > > - st->chip_info =
> > > > > - &ad7887_chip_info_tbl[spi_get_device_id(spi)->driver_data];
> > > > > + st->chip_info = info;
> > > > >
> > > > > spi_set_drvdata(spi, indio_dev);
> > > > > st->spi = spi;
> > > > >
> > > > > - indio_dev->name = spi_get_device_id(spi)->name;
> > > > > + indio_dev->name = st->chip_info->name;
> > > > > indio_dev->info = &ad7887_info;
> > > > > indio_dev->modes = INDIO_DIRECT_MODE;
> > > > >
> > > > > @@ -336,18 +343,18 @@ static int ad7887_probe(struct spi_device *spi)
> > > > > return devm_iio_device_register(&spi->dev, indio_dev);
> > > > > }
> > > > >
> > > > > -static const struct spi_device_id ad7887_id[] = {
> > > > > - {"ad7887", ID_AD7887},
> > > > > - {}
> > > > > +static const struct of_device_id ad7887_of_match[] = {
> > > > > + { .compatible = "adi,ad7887", .data = &ad7887_chip_info_tbl[ID_AD7887] },
> > > > > + { }
> > > > > };
> > > > > -MODULE_DEVICE_TABLE(spi, ad7887_id);
> > > > > +MODULE_DEVICE_TABLE(of, ad7887_of_match);
> > > > >
> > > > > static struct spi_driver ad7887_driver = {
> > > > > .driver = {
> > > > > .name = "ad7887",
> > > > > + .of_match_table = ad7887_of_match,
> > > > > },
> > > > > .probe = ad7887_probe,
> > > > > - .id_table = ad7887_id,
> > > > > };
> > > > > module_spi_driver(ad7887_driver);
> > > > >
> > > >
> > >
>