linux-kernel - Re: [PATCH v2 3/5] iio: mxs-lradc: add scale attribute to channels

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Message-Id: <201307191630.17149.marex@denx.de>
Date:	Fri, 19 Jul 2013 16:30:16 +0200
From:	Marek Vasut <marex@...x.de>
To:	Hector Palacios <hector.palacios@...i.com>
Cc:	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
	devicetree-discuss@...ts.ozlabs.org,
	alexandre.belloni@...e-electrons.com, jic23@...nel.org,
	lars@...afoo.de, fabio.estevam@...escale.com
Subject: Re: [PATCH v2 3/5] iio: mxs-lradc: add scale attribute to channels

Dear Hector Palacios,

> Some LRADC channels have fixed pre-dividers and all have an optional
> divider by two which allows a maximum input voltage of VDDIO - 50mV.
> 
> This patch
>  - adds the scaling info flag to all channels
>  - grabs the max reference voltage per channel from DT
>    (where the fixed pre-dividers apply)
>  - allows to read the scaling attribute (computed from the Vref)
> 
> Signed-off-by: Hector Palacios <hector.palacios@...i.com>.
> ---
>  drivers/staging/iio/adc/mxs-lradc.c | 81
> ++++++++++++++++++++++++------------- 1 file changed, 52 insertions(+), 29
> deletions(-)
> 
> diff --git a/drivers/staging/iio/adc/mxs-lradc.c
> b/drivers/staging/iio/adc/mxs-lradc.c index 91282dc..99e5790 100644
> --- a/drivers/staging/iio/adc/mxs-lradc.c
> +++ b/drivers/staging/iio/adc/mxs-lradc.c
> @@ -141,6 +141,8 @@ struct mxs_lradc {
> 
>  	struct completion	completion;
> 
> +	uint32_t		vref_mv[LRADC_MAX_TOTAL_CHANS];
> +
>  	/*
>  	 * Touchscreen LRADC channels receives a private slot in the CTRL4
>  	 * register, the slot #7. Therefore only 7 slots instead of 8 in the
> @@ -228,39 +230,12 @@ struct mxs_lradc {
>  #define LRADC_RESOLUTION			12
>  #define LRADC_SINGLE_SAMPLE_MASK		((1 << LRADC_RESOLUTION) - 1)
> 
> -/*
> - * Raw I/O operations
> - */
> -static int mxs_lradc_read_raw(struct iio_dev *iio_dev,
> +static int mxs_lradc_read_single(struct iio_dev *iio_dev,
>  			const struct iio_chan_spec *chan,
>  			int *val, int *val2, long m)
>  {
>  	struct mxs_lradc *lradc = iio_priv(iio_dev);
>  	int ret;
> -	unsigned long mask;
> -
> -	if (m != IIO_CHAN_INFO_RAW)
> -		return -EINVAL;
> -
> -	/* Check for invalid channel */
> -	if (chan->channel > LRADC_MAX_TOTAL_CHANS)
> -		return -EINVAL;

This was already resolved, so this patch won't apply I'm afraid.

> -	/* Validate the channel if it doesn't intersect with reserved chans. */
> -	bitmap_set(&mask, chan->channel, 1);
> -	ret = iio_validate_scan_mask_onehot(iio_dev, &mask);
> -	if (ret)
> -		return -EINVAL;
> -
> -	/*
> -	 * See if there is no buffered operation in progess. If there is, simply
> -	 * bail out. This can be improved to support both buffered and raw IO at
> -	 * the same time, yet the code becomes horribly complicated. Therefore I
> -	 * applied KISS principle here.
> -	 */
> -	ret = mutex_trylock(&lradc->lock);
> -	if (!ret)
> -		return -EBUSY;
> 
>  	INIT_COMPLETION(lradc->completion);
> 
> @@ -300,6 +275,47 @@ err:
>  	writel(LRADC_CTRL1_LRADC_IRQ_EN(0),
>  		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
> 
> +	return ret;
> +}
> +
> +/*
> + * Raw I/O operations
> + */
> +static int mxs_lradc_read_raw(struct iio_dev *iio_dev,
> +			const struct iio_chan_spec *chan,
> +			int *val, int *val2, long m)
> +{
> +	struct mxs_lradc *lradc = iio_priv(iio_dev);
> +	int ret;
> +
> +	/*
> +	 * See if there is no buffered operation in progress. If there is, 
simply
> +	 * bail out. This can be improved to support both buffered and raw IO at
> +	 * the same time, yet the code becomes horribly complicated. Therefore I
> +	 * applied KISS principle here.
> +	 */
> +	ret = mutex_trylock(&lradc->lock);
> +	if (!ret)
> +		return -EBUSY;
> +
> +	/* Check for invalid channel */
> +	if (chan->channel > LRADC_MAX_TOTAL_CHANS)
> +		ret = -EINVAL;
> +
> +	switch (m) {
> +	case IIO_CHAN_INFO_RAW:
> +		ret = mxs_lradc_read_single(iio_dev, chan, val, val2, m);
> +		break;
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = lradc->vref_mv[chan->channel];
> +		*val2 = chan->scan_type.realbits;
> +		ret = IIO_VAL_FRACTIONAL_LOG2;
> +		break;
> +	default:
> +		ret = -EINVAL;
> +		break;
> +	}
> +
>  	mutex_unlock(&lradc->lock);
> 
>  	return ret;
> @@ -821,7 +837,8 @@ static const struct iio_buffer_setup_ops
> mxs_lradc_buffer_ops = { .type = (chan_type),					
\
>  	.indexed = 1,						\
>  	.scan_index = (idx),					\
> -	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
> +			      BIT(IIO_CHAN_INFO_SCALE),		\
>  	.channel = (idx),					\
>  	.scan_type = {						\
>  		.sign = 'u',					\
> @@ -960,6 +977,12 @@ static int mxs_lradc_probe(struct platform_device
> *pdev) goto err_addr;
>  	}
> 
> +	/* Grab Vref array from DT */
> +	ret = of_property_read_u32_array(node, "fsl,vref", lradc->vref_mv,
> +					 LRADC_MAX_TOTAL_CHANS);
> +	if (ret)
> +		goto err_addr;
> +
>  	platform_set_drvdata(pdev, iio);
> 
>  	init_completion(&lradc->completion);

Otherwise:

Acked-by: Marek Vasut <marex@...x.de>


Marek Vasut
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