Re: [PATCH v2] iio: frequency: ad983x: replace do_div() with div64_ul().

[David Lechner <dlechner@baylibre.com>]

On 4/9/26 10:01 AM, Joshua Crofts wrote:
> Coccinelle reported the following in both ad983x drivers:
> do_div() does a 64-by-32 division, please consider using
> div64_ul instead.
> 
> Fix this by replacing do_div() with div64_ul(), which
> safely handles 64-bit dividends and unsigned long
> divisors across all architectures.
> 
> Signed-off-by: Joshua Crofts <joshua.crofts1@gmail.com>
> ---
> v2:

Please don't send v2 or later revisions in reply to v1. It breaks
some workflows. Start a new thread instead.

>  - resent email with corrected addresses

Instead of a v2, you can just add a RESEND prefix to the subject line
in cases like this. But do include an explanation like this when you
do that.

> 
>  drivers/staging/iio/frequency/ad9832.c | 3 ++-
>  drivers/staging/iio/frequency/ad9834.c | 3 ++-
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/iio/frequency/ad9832.c b/drivers/staging/iio/frequency/ad9832.c
> index b87ea1781b..61ee93263a 100644
> --- a/drivers/staging/iio/frequency/ad9832.c
> +++ b/drivers/staging/iio/frequency/ad9832.c
> @@ -13,6 +13,7 @@
>  #include <linux/device.h>
>  #include <linux/err.h>
>  #include <linux/kernel.h>
> +#include <linux/math64.h>
>  #include <linux/module.h>
>  #include <linux/regulator/consumer.h>
>  #include <linux/slab.h>
> @@ -115,7 +116,7 @@ static unsigned long ad9832_calc_freqreg(unsigned long mclk, unsigned long fout)
>  {
>  	unsigned long long freqreg = (u64)fout *
>  				     (u64)((u64)1L << AD9832_FREQ_BITS);

I would expect checkpatch to complain that there is no blank line
between variable declarations and the rest of the code here.

> -	do_div(freqreg, mclk);
> +	freqreg = div64_ul(freqreg, mclk);
>  	return freqreg;

We can just return directly now.

	return div64_ul(freqreg, mclk);

>  }
>  
> diff --git a/drivers/staging/iio/frequency/ad9834.c b/drivers/staging/iio/frequency/ad9834.c
> index d339d5e8e0..83d0e1360c 100644
> --- a/drivers/staging/iio/frequency/ad9834.c
> +++ b/drivers/staging/iio/frequency/ad9834.c
> @@ -10,6 +10,7 @@
>  #include <linux/workqueue.h>
>  #include <linux/device.h>
>  #include <linux/kernel.h>
> +#include <linux/math64.h>
>  #include <linux/slab.h>
>  #include <linux/sysfs.h>
>  #include <linux/list.h>
> @@ -101,7 +102,7 @@ static unsigned int ad9834_calc_freqreg(unsigned long mclk, unsigned long fout)
>  {
>  	unsigned long long freqreg = (u64)fout * (u64)BIT(AD9834_FREQ_BITS);
>  
> -	do_div(freqreg, mclk);
> +	freqreg = div64_ul(freqreg, mclk);
>  	return freqreg;

ditto.

>  }
>