linux-kernel - Re: [PATCH v1 1/1] gpio: dwapb: clarify usage of the register file version

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Message-ID: <20211201122734.o7m5xb6zh4ngjpo7@mobilestation>
Date:   Wed, 1 Dec 2021 15:27:34 +0300
From:   Serge Semin <fancer.lancer@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Hoan Tran <hoan@...amperecomputing.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>
Subject: Re: [PATCH v1 1/1] gpio: dwapb: clarify usage of the register file
 version

On Tue, Nov 30, 2021 at 06:49:56PM +0200, Andy Shevchenko wrote:
> First of all, it's obvious that different versions can't be provided
> simultaneously. Hence, versions can't be bit masks.
> 
> Second, due to above we have to mask out the version field in the flags
> and only that can be evaluated against the certain version.
> 
> Clarify all above by:
>  - introducing GPIO_REG_OFFSET_V1 and GPIO_REG_OFFSET_MASK
>  - replacing conditional to mask out bits and compare to a version
> 
> Luckily there is no functional change (at least intended), so no need
> to backport this.

Seems reasonable. Thanks.
Acked-by: Serge Semin <fancer.lancer@...il.com>

-Sergey

> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/gpio/gpio-dwapb.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-dwapb.c b/drivers/gpio/gpio-dwapb.c
> index f98fa33e1679..ec0767d7800d 100644
> --- a/drivers/gpio/gpio-dwapb.c
> +++ b/drivers/gpio/gpio-dwapb.c
> @@ -53,7 +53,9 @@
>  #define GPIO_SWPORT_DR_STRIDE	0x0c /* register stride 3*32 bits */
>  #define GPIO_SWPORT_DDR_STRIDE	0x0c /* register stride 3*32 bits */
>  
> +#define GPIO_REG_OFFSET_V1	0
>  #define GPIO_REG_OFFSET_V2	1
> +#define GPIO_REG_OFFSET_MASK	BIT(0)
>  
>  #define GPIO_INTMASK_V2		0x44
>  #define GPIO_INTTYPE_LEVEL_V2	0x34
> @@ -141,7 +143,7 @@ static inline u32 gpio_reg_v2_convert(unsigned int offset)
>  
>  static inline u32 gpio_reg_convert(struct dwapb_gpio *gpio, unsigned int offset)
>  {
> -	if (gpio->flags & GPIO_REG_OFFSET_V2)
> +	if ((gpio->flags & GPIO_REG_OFFSET_MASK) == GPIO_REG_OFFSET_V2)
>  		return gpio_reg_v2_convert(offset);
>  
>  	return offset;
> @@ -668,15 +670,15 @@ static int dwapb_get_clks(struct dwapb_gpio *gpio)
>  }
>  
>  static const struct of_device_id dwapb_of_match[] = {
> -	{ .compatible = "snps,dw-apb-gpio", .data = (void *)0},
> +	{ .compatible = "snps,dw-apb-gpio", .data = (void *)GPIO_REG_OFFSET_V1},
>  	{ .compatible = "apm,xgene-gpio-v2", .data = (void *)GPIO_REG_OFFSET_V2},
>  	{ /* Sentinel */ }
>  };
>  MODULE_DEVICE_TABLE(of, dwapb_of_match);
>  
>  static const struct acpi_device_id dwapb_acpi_match[] = {
> -	{"HISI0181", 0},
> -	{"APMC0D07", 0},
> +	{"HISI0181", GPIO_REG_OFFSET_V1},
> +	{"APMC0D07", GPIO_REG_OFFSET_V1},
>  	{"APMC0D81", GPIO_REG_OFFSET_V2},
>  	{ }
>  };
> -- 
> 2.33.0
>