linux-kernel - Re: [PATCH 2/2] iio: adc: at91_adc: const-ify some driver data

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Message-ID: <20200929165510.1e609883@archlinux>
Date:   Tue, 29 Sep 2020 16:55:10 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Alexandru Ardelean <alexandru.ardelean@...log.com>
Cc:     <linux-iio@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <nicolas.ferre@...rochip.com>,
        <alexandre.belloni@...tlin.com>, <ludovic.desroches@...rochip.com>
Subject: Re: [PATCH 2/2] iio: adc: at91_adc: const-ify some driver data

On Mon, 28 Sep 2020 15:54:24 +0300
Alexandru Ardelean <alexandru.ardelean@...log.com> wrote:

> The main intent is to get rid of the cast for the void-pointer returned by
> of_device_get_match_data().
> 
> This requires const-ifying the 'caps' and 'registers' references on the
> at91_adc_state struct.
> 
> The caps can be obtained also from the old platform_data (in the
> at91_adc_probe_pdata() function), but that cast is not touched in this
> patch, since the old platform_data should be removed/cleaned-away.
> Also, that cast deals with converting a kernel_ulong_t type to a pointer.
> So, updating that cast doesn't yield any benefit.
> 
> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
Good change. I'll pick this up when patch 1 is ready.

Thanks,

Jonathan

> ---
>  drivers/iio/adc/at91_adc.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
> index c9ec0a4a357e..7d846a2852a5 100644
> --- a/drivers/iio/adc/at91_adc.c
> +++ b/drivers/iio/adc/at91_adc.c
> @@ -202,7 +202,7 @@ struct at91_adc_state {
>  	struct mutex		lock;
>  	u8			num_channels;
>  	void __iomem		*reg_base;
> -	struct at91_adc_reg_desc *registers;
> +	const struct at91_adc_reg_desc *registers;
>  	u32			startup_time;
>  	u8			sample_hold_time;
>  	bool			sleep_mode;
> @@ -214,7 +214,7 @@ struct at91_adc_state {
>  	u32			res;		/* resolution used for convertions */
>  	bool			low_res;	/* the resolution corresponds to the lowest one */
>  	wait_queue_head_t	wq_data_avail;
> -	struct at91_adc_caps	*caps;
> +	const struct at91_adc_caps	*caps;
>  
>  	/*
>  	 * Following ADC channels are shared by touchscreen:
> @@ -550,7 +550,7 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
>  {
>  	struct iio_dev *idev = iio_trigger_get_drvdata(trig);
>  	struct at91_adc_state *st = iio_priv(idev);
> -	struct at91_adc_reg_desc *reg = st->registers;
> +	const struct at91_adc_reg_desc *reg = st->registers;
>  	u32 status = at91_adc_readl(st, reg->trigger_register);
>  	int value;
>  	u8 bit;
> @@ -876,7 +876,7 @@ static int at91_adc_probe_dt(struct iio_dev *idev,
>  	if (!node)
>  		return -EINVAL;
>  
> -	st->caps = (struct at91_adc_caps *)of_device_get_match_data(&pdev->dev);
> +	st->caps = of_device_get_match_data(&pdev->dev);
>  
>  	st->use_external = of_property_read_bool(node, "atmel,adc-use-external-triggers");
>