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

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Message-ID: <20201117110111.0000468a@Huawei.com>
Date:   Tue, 17 Nov 2020 11:01:11 +0000
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Alexandru Ardelean <alexandru.ardelean@...log.com>
CC:     <linux-iio@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <jic23@...nel.org>,
        <robh+dt@...nel.org>, Vaishnav M A <vaishnav@...gleboard.org>,
        <andy.shevchenko@...il.com>
Subject: Re: [PATCH 2/3] iio: adc: ad7887: convert driver to full DT probing

On Tue, 17 Nov 2020 09:52:53 +0200
Alexandru Ardelean <alexandru.ardelean@...log.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@...log.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.

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);
>