linux-kernel - Re: [RFC v7 4/6] gpio: mpfs: add polarfire soc gpio support

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Message-ID: <CACRpkdbRE695f-+do1HYpOZ6e4qxgUBWJzEPO2hTCuZ3xxYHQg@mail.gmail.com>
Date: Mon, 5 Aug 2024 10:04:53 +0200
From: Linus Walleij <linus.walleij@...aro.org>
To: Conor Dooley <conor.dooley@...rochip.com>
Cc: linux-kernel@...r.kernel.org, conor@...nel.org, 
	Marc Zyngier <maz@...nel.org>, Daire McNamara <daire.mcnamara@...rochip.com>, 
	Bartosz Golaszewski <brgl@...ev.pl>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	linux-riscv@...ts.infradead.org, linux-gpio@...r.kernel.org, 
	devicetree@...r.kernel.org, Lewis Hanly <lewis.hanly@...rochip.com>
Subject: Re: [RFC v7 4/6] gpio: mpfs: add polarfire soc gpio support

On Tue, Jul 23, 2024 at 1:28 PM Conor Dooley <conor.dooley@...rochip.com> wrote:


> From: Lewis Hanly <lewis.hanly@...rochip.com>
>
> Add a driver to support the Polarfire SoC gpio controller
>
> Signed-off-by: Lewis Hanly <lewis.hanly@...rochip.com>
> Signed-off-by: Conor Dooley <conor.dooley@...rochip.com>

Just a comment on second thought:

> +config GPIO_POLARFIRE_SOC
> +       bool "Microchip FPGA GPIO support"
> +       depends on OF_GPIO
> +       select GPIOLIB_IRQCHIP

select GPIO_GENERIC?

> +static int mpfs_gpio_direction_input(struct gpio_chip *gc, unsigned int gpio_index)
> +{
> +       struct mpfs_gpio_chip *mpfs_gpio = gpiochip_get_data(gc);
> +       u32 gpio_cfg;
> +       unsigned long flags;
> +
> +       raw_spin_lock_irqsave(&mpfs_gpio->lock, flags);
> +
> +       gpio_cfg = readl(mpfs_gpio->base + MPFS_GPIO_CTRL(gpio_index));
> +       gpio_cfg |= MPFS_GPIO_EN_IN;
> +       gpio_cfg &= ~(MPFS_GPIO_EN_OUT | MPFS_GPIO_EN_OUT_BUF);

OK this part is unique...

> +static int mpfs_gpio_direction_output(struct gpio_chip *gc, unsigned int gpio_index, int value)
> +{
> +       struct mpfs_gpio_chip *mpfs_gpio = gpiochip_get_data(gc);
> +       u32 gpio_cfg;
> +       unsigned long flags;
> +
> +       raw_spin_lock_irqsave(&mpfs_gpio->lock, flags);
> +
> +       gpio_cfg = readl(mpfs_gpio->base + MPFS_GPIO_CTRL(gpio_index));
> +       gpio_cfg |= MPFS_GPIO_EN_OUT | MPFS_GPIO_EN_OUT_BUF;

Also here

> +static int mpfs_gpio_get_direction(struct gpio_chip *gc,
> +                                  unsigned int gpio_index)
> +static int mpfs_gpio_get(struct gpio_chip *gc,
> +                        unsigned int gpio_index)
> +static void mpfs_gpio_set(struct gpio_chip *gc, unsigned int gpio_index, int value)

But these are just MMIO functions.

Is it possible to use augmented generic MMIO, i.e just override these
two functions that
need special handling?

Yours,
Linus Walleij