linux-kernel - Re: [PATCH v2] gpio: dwapb: Add support for next generation of X-Gene SoC

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Date:   Fri, 17 Feb 2017 12:23:10 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Hoan Tran <hotran@....com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Alexandre Courbot <gnurou@...il.com>,
        Jamie Iles <jamie@...ieiles.com>,
        Weike Chen <alvin.chen@...el.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Loc Ho <lho@....com>, Duc Dang <dhdang@....com>
Subject: Re: [PATCH v2] gpio: dwapb: Add support for next generation of X-Gene SoC

On Fri, Feb 17, 2017 at 3:01 AM, Hoan Tran <hotran@....com> wrote:
> Next generation of X-Gene SoC's GPIO hardware register map is very
> similar to DW GPIO. It only differs by a few register addresses.
> This patch modifies DW GPIO driver to accommodate the difference
> in a few register addresses.

> --- a/drivers/gpio/gpio-dwapb.c
> +++ b/drivers/gpio/gpio-dwapb.c
> @@ -55,6 +56,13 @@
>  #define GPIO_SWPORT_DR_SIZE    (GPIO_SWPORTB_DR - GPIO_SWPORTA_DR)
>  #define GPIO_SWPORT_DDR_SIZE   (GPIO_SWPORTB_DDR - GPIO_SWPORTA_DDR)
>
> +#define GPIO_REG_OFFSET_V2     1

+ empty line

> +#define GPIO_INTMASK_V2                0x44
> +#define GPIO_INTTYPE_LEVEL_V2  0x34
> +#define GPIO_INT_POLARITY_V2   0x38
> +#define GPIO_INTSTATUS_V2      0x3c
> +#define GPIO_PORTA_EOI_V2      0x40

> +       unsigned int            flags;

> +static inline u32 gpio_reg_convert(struct dwapb_gpio *gpio, unsigned int offset)
> +{

> +       if (!(gpio->flags & GPIO_REG_OFFSET_V2))
> +               return offset;

I would split this to to functions:

... u32 gpio_reg_convert(...) {
 if (gpio->flags & ...)
  return gpio_reg_v2_convert();
 return offset;
}

> +       switch (offset) {
> +       case GPIO_INTMASK:
> +               return GPIO_INTMASK_V2;
> +       case GPIO_INTTYPE_LEVEL:
> +               return GPIO_INTTYPE_LEVEL_V2;
> +       case GPIO_INT_POLARITY:
> +               return GPIO_INT_POLARITY_V2;
> +       case GPIO_INTSTATUS:
> +               return GPIO_INTSTATUS_V2;
> +       case GPIO_PORTA_EOI:
> +               return GPIO_PORTA_EOI_V2;
> +       }
> +
> +       return offset;
> +}

> -       return gc->read_reg(reg_base + offset);
> +       return gc->read_reg(reg_base + gpio_reg_convert(gpio, offset));

I'm still not convinced why we can't use

gc->read_reg = ..._read_reg_v2;

It will be called only in case of v2.

Sorry if I missed the point.

>  static int dwapb_gpio_to_irq(struct gpio_chip *gc, unsigned offset)
> @@ -336,8 +366,8 @@ static void dwapb_configure_irqs(struct dwapb_gpio *gpio,
>                 ct->chip.irq_disable = dwapb_irq_disable;
>                 ct->chip.irq_request_resources = dwapb_irq_reqres;
>                 ct->chip.irq_release_resources = dwapb_irq_relres;
> -               ct->regs.ack = GPIO_PORTA_EOI;
> -               ct->regs.mask = GPIO_INTMASK;
> +               ct->regs.ack = gpio_reg_convert(gpio, GPIO_PORTA_EOI);
> +               ct->regs.mask = gpio_reg_convert(gpio, GPIO_INTMASK);
>                 ct->type = IRQ_TYPE_LEVEL_MASK;
>         }
>
> @@ -520,6 +550,21 @@ static void dwapb_gpio_unregister(struct dwapb_gpio *gpio)
>         return pdata;
>  }


> +static const struct of_device_id dwapb_of_match[] = {
> +       { .compatible = "snps,dw-apb-gpio", .data = (void *)0},
> +       { .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},
> +       {"APMC0D81", GPIO_REG_OFFSET_V2},
> +       { }
> +};
> +MODULE_DEVICE_TABLE(acpi, dwapb_acpi_match);
> +

Since you are adding stuff here, I would consider at least two patches:
1. Move tables up here
2. Add and enable V2

or even 3:
1. Move tables
2. Extend functionality
3. Add ACPI ID

> +       of_devid = of_match_device(dwapb_of_match, dev);
> +       if (of_devid) {

Why not to follow the below pattern, i.e.

if (dev.of_node) {
      const struct of_device_id *of_id;
...
} else if (has_acpi_companion(...)) {
...
}

?

> +               if (of_devid->data)
> +                       gpio->flags = (uintptr_t)of_devid->data;

Type inconsistency.
(unsigned int) would work.

> +       } else {
> +               const struct acpi_device_id *acpi_id;
> +
> +               acpi_id = acpi_match_device(dwapb_acpi_match, &pdev->dev);
> +               if (acpi_id) {
> +                       if (acpi_id->driver_data)
> +                               gpio->flags = acpi_id->driver_data;
> +               }
> +       }

> @@ -581,19 +642,6 @@ static int dwapb_gpio_remove(struct platform_device *pdev)

> -static const struct of_device_id dwapb_of_match[] = {
> -       { .compatible = "snps,dw-apb-gpio" },
> -       { /* Sentinel */ }
> -};
> -MODULE_DEVICE_TABLE(of, dwapb_of_match);
> -
> -static const struct acpi_device_id dwapb_acpi_match[] = {
> -       {"HISI0181", 0},
> -       {"APMC0D07", 0},
> -       { }
> -};
> -MODULE_DEVICE_TABLE(acpi, dwapb_acpi_match);
> -

-- 
With Best Regards,
Andy Shevchenko