linux-kernel - Re: [PATCH] iio: adc: ad7887: Cleanup channel assignment

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Date:   Sat, 23 Nov 2019 16:39:52 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Beniamin Bia <beniamin.bia@...log.com>
Cc:     <lars@...afoo.de>, <Michael.Hennerich@...log.com>,
        <pmeerw@...erw.net>, <linux-iio@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <biabeniamin@...look.com>,
        <knaack.h@....de>
Subject: Re: [PATCH] iio: adc: ad7887: Cleanup channel assignment

On Mon, 18 Nov 2019 17:09:27 +0200
Beniamin Bia <beniamin.bia@...log.com> wrote:

> The channels specification assignment in chip info was simplified.
> This patch makes supporting other devices by this driver easier.
> 
> Signed-off-by: Beniamin Bia <beniamin.bia@...log.com>

I'm not entirely keen on the trick with channel ordering to support
the use of the second input as vref.

I would just pay the cost of having two different iio_chan_spec
arrays and pick the relevant one.

Jonathan


> ---
>  drivers/iio/adc/ad7887.c | 71 ++++++++++++++++++----------------------
>  1 file changed, 31 insertions(+), 40 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7887.c b/drivers/iio/adc/ad7887.c
> index 6223043e432b..65d1338d9392 100644
> --- a/drivers/iio/adc/ad7887.c
> +++ b/drivers/iio/adc/ad7887.c
> @@ -43,11 +43,12 @@ enum ad7887_channels {
>  /**
>   * struct ad7887_chip_info - chip specifc information
>   * @int_vref_mv:	the internal reference voltage
> - * @channel:		channel specification
> + * @channels:		channels specification
>   */
>  struct ad7887_chip_info {
>  	u16				int_vref_mv;
> -	struct iio_chan_spec		channel[3];
> +	const struct iio_chan_spec	*channels;
> +	unsigned int			num_channels;
>  };
>  
>  struct ad7887_state {
> @@ -183,45 +184,36 @@ static int ad7887_read_raw(struct iio_dev *indio_dev,
>  	return -EINVAL;
>  }
>  
> +#define AD7887_CHANNEL(x) { \
> +	.type = IIO_VOLTAGE, \
> +	.indexed = 1, \
> +	.channel = (x), \
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> +	.address = (x), \
> +	.scan_index = (x), \
> +	.scan_type = { \
> +		.sign = 'u', \
> +		.realbits = 12, \
> +		.storagebits = 16, \
> +		.shift = 0, \
> +		.endianness = IIO_BE, \
> +	}, \
> +}
> +
> +static const struct iio_chan_spec ad7887_channels[] = {
> +	IIO_CHAN_SOFT_TIMESTAMP(8),
> +	AD7887_CHANNEL(0),
> +	AD7887_CHANNEL(1),
> +};
>  
>  static const struct ad7887_chip_info ad7887_chip_info_tbl[] = {
>  	/*
>  	 * More devices added in future
>  	 */
>  	[ID_AD7887] = {
> -		.channel[0] = {
> -			.type = IIO_VOLTAGE,
> -			.indexed = 1,
> -			.channel = 1,
> -			.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> -			.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
> -			.address = 1,
> -			.scan_index = 1,
> -			.scan_type = {
> -				.sign = 'u',
> -				.realbits = 12,
> -				.storagebits = 16,
> -				.shift = 0,
> -				.endianness = IIO_BE,
> -			},
> -		},
> -		.channel[1] = {
> -			.type = IIO_VOLTAGE,
> -			.indexed = 1,
> -			.channel = 0,
> -			.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> -			.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
> -			.address = 0,
> -			.scan_index = 0,
> -			.scan_type = {
> -				.sign = 'u',
> -				.realbits = 12,
> -				.storagebits = 16,
> -				.shift = 0,
> -				.endianness = IIO_BE,
> -			},
> -		},
> -		.channel[2] = IIO_CHAN_SOFT_TIMESTAMP(2),
> +		.channels = ad7887_channels,
> +		.num_channels = ARRAY_SIZE(ad7887_channels),
>  		.int_vref_mv = 2500,
>  	},
>  };
> @@ -284,6 +276,9 @@ static int ad7887_probe(struct spi_device *spi)
>  	spi_message_init(&st->msg[AD7887_CH0]);
>  	spi_message_add_tail(&st->xfer[0], &st->msg[AD7887_CH0]);
>  
> +	indio_dev->channels = st->chip_info->channels;
> +	indio_dev->num_channels = st->chip_info->num_channels;
> +
>  	if (pdata && pdata->en_dual) {
>  		st->tx_cmd_buf[2] = AD7887_CH_AIN1 | mode;
>  
> @@ -305,12 +300,8 @@ static int ad7887_probe(struct spi_device *spi)
>  
>  		spi_message_init(&st->msg[AD7887_CH1]);
>  		spi_message_add_tail(&st->xfer[3], &st->msg[AD7887_CH1]);
> -
> -		indio_dev->channels = st->chip_info->channel;
> -		indio_dev->num_channels = 3;
>  	} else {
> -		indio_dev->channels = &st->chip_info->channel[1];
> -		indio_dev->num_channels = 2;
> +		indio_dev->num_channels = st->chip_info->num_channels - 1;
>  	}
>  
>  	ret = iio_triggered_buffer_setup(indio_dev, &iio_pollfunc_store_time,