The macro clk_div_mask() currently wraps to zero when width is 32 due to
1 << 32 being undefined behavior. This leads to incorrect mask generation
and prevents correct retrieval of register field values for 32-bit-wide
dividers.

Although it is unlikely to exhaust all U32_MAX div, some clock IPs may rely
on a 32-bit val entry in their div_table to match a div, so providing a
full 32-bit mask is necessary.

Fix this by casting 1 to long, ensuring proper behavior for valid widths up
to 32.

Signed-off-by: Junhui Liu <junhui.liu@pigmoral.tech>
---
 include/linux/clk-provider.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 630705a47129453c241f1b1755f2c2f2a7ed8f77..a651ccaf1b44ff905c2bd4b9a7043f9e2169d27f 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -720,7 +720,7 @@ struct clk_divider {
 	spinlock_t	*lock;
 };
 
-#define clk_div_mask(width)	((1 << (width)) - 1)
+#define clk_div_mask(width)	((1L << (width)) - 1)
 #define to_clk_divider(_hw) container_of(_hw, struct clk_divider, hw)
 
 #define CLK_DIVIDER_ONE_BASED		BIT(0)

-- 
2.51.0

On Mon, Sep 22, 2025 at 10:51:47PM +0800, Junhui Liu wrote:
> The macro clk_div_mask() currently wraps to zero when width is 32 due to
> 1 << 32 being undefined behavior. This leads to incorrect mask generation
> and prevents correct retrieval of register field values for 32-bit-wide
> dividers.
> 
> Although it is unlikely to exhaust all U32_MAX div, some clock IPs may rely
> on a 32-bit val entry in their div_table to match a div, so providing a
> full 32-bit mask is necessary.
> 
> Fix this by casting 1 to long, ensuring proper behavior for valid widths up
> to 32.
> 
> Signed-off-by: Junhui Liu <junhui.liu@pigmoral.tech>
> ---
>  include/linux/clk-provider.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> index 630705a47129453c241f1b1755f2c2f2a7ed8f77..a651ccaf1b44ff905c2bd4b9a7043f9e2169d27f 100644
> --- a/include/linux/clk-provider.h
> +++ b/include/linux/clk-provider.h
> @@ -720,7 +720,7 @@ struct clk_divider {
>  	spinlock_t	*lock;
>  };
>  
> -#define clk_div_mask(width)	((1 << (width)) - 1)
> +#define clk_div_mask(width)	((1L << (width)) - 1)
Reviewed-by: Troy Mitchell <troy.mitchell@linux.spacemit.com>
>  #define to_clk_divider(_hw) container_of(_hw, struct clk_divider, hw)
>  
>  #define CLK_DIVIDER_ONE_BASED		BIT(0)
> 
> -- 
> 2.51.0
> 
> 
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