linux-kernel - Re: [PATCH 4/4] gpio: tqmx86: add support for changing GPIO directions

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Message-ID: <CAMRc=McKcRbXsmKq-qBfK62PCzR3sgRp6592c2pGAztVo5omCA@mail.gmail.com>
Date: Wed, 11 Dec 2024 16:13:58 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Matthias Schiffer <matthias.schiffer@...tq-group.com>
Cc: Linus Walleij <linus.walleij@...aro.org>, linux@...tq-group.com, 
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] gpio: tqmx86: add support for changing GPIO directions

On Mon, Dec 9, 2024 at 11:36 AM Matthias Schiffer
<matthias.schiffer@...tq-group.com> wrote:
>
> Only GPIOs 4..7 have IRQ support on the TQMx86 variants currently handled
> by the driver, but apart from that, changing directions works fine. The
> default directions are left unchanged (0..3 output, 4..7 input) to match
> the COM Express specification.
>
> A tqmx86_gpio_set() variant without locking is introduced as a new
> helper.
>
> Signed-off-by: Matthias Schiffer <matthias.schiffer@...tq-group.com>
> ---
>  drivers/gpio/gpio-tqmx86.c | 46 ++++++++++++++++++++++++++------------
>  1 file changed, 32 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpio/gpio-tqmx86.c b/drivers/gpio/gpio-tqmx86.c
> index 54e7e193bb209..4c7e7b5950426 100644
> --- a/drivers/gpio/gpio-tqmx86.c
> +++ b/drivers/gpio/gpio-tqmx86.c
> @@ -84,6 +84,14 @@ static int tqmx86_gpio_get(struct gpio_chip *chip, unsigned int offset)
>         return !!(tqmx86_gpio_read(gpio, TQMX86_GPIOD) & BIT(offset));
>  }
>
> +static void _tqmx86_gpio_set(struct tqmx86_gpio_data *gpio, unsigned int offset,
> +                            int value)
> +       __must_hold(&gpio->spinlock)
> +{
> +       __assign_bit(offset, gpio->output, value);
> +       tqmx86_gpio_write(gpio, bitmap_get_value8(gpio->output, 0), TQMX86_GPIOD);
> +}
> +
>  static void tqmx86_gpio_set(struct gpio_chip *chip, unsigned int offset,
>                             int value)
>  {
> @@ -91,40 +99,50 @@ static void tqmx86_gpio_set(struct gpio_chip *chip, unsigned int offset,
>         unsigned long flags;
>
>         raw_spin_lock_irqsave(&gpio->spinlock, flags);
> -       __assign_bit(offset, gpio->output, value);
> -       tqmx86_gpio_write(gpio, bitmap_get_value8(gpio->output, 0), TQMX86_GPIOD);
> +       _tqmx86_gpio_set(gpio, offset, value);
>         raw_spin_unlock_irqrestore(&gpio->spinlock, flags);
>  }
>
>  static int tqmx86_gpio_direction_input(struct gpio_chip *chip,
>                                        unsigned int offset)
>  {
> -       /* Direction cannot be changed. Validate is an input. */
> -       if (BIT(offset) & TQMX86_DIR_INPUT_MASK)
> -               return 0;
> -       else
> -               return -EINVAL;
> +       struct tqmx86_gpio_data *gpio = gpiochip_get_data(chip);
> +       unsigned long flags;
> +
> +       raw_spin_lock_irqsave(&gpio->spinlock, flags);
> +       tqmx86_gpio_clrsetbits(gpio, BIT(offset), 0, TQMX86_GPIODD);
> +       raw_spin_unlock_irqrestore(&gpio->spinlock, flags);

Maybe switch to using lock guards if you're changing the code anyway?

Bart

> +
> +       return 0;
>  }
>
>  static int tqmx86_gpio_direction_output(struct gpio_chip *chip,
>                                         unsigned int offset,
>                                         int value)
>  {
> -       /* Direction cannot be changed, validate is an output */
> -       if (BIT(offset) & TQMX86_DIR_INPUT_MASK)
> -               return -EINVAL;
> +       struct tqmx86_gpio_data *gpio = gpiochip_get_data(chip);
> +       unsigned long flags;
> +
> +       raw_spin_lock_irqsave(&gpio->spinlock, flags);
> +       _tqmx86_gpio_set(gpio, offset, value);
> +       tqmx86_gpio_clrsetbits(gpio, 0, BIT(offset), TQMX86_GPIODD);
> +       raw_spin_unlock_irqrestore(&gpio->spinlock, flags);
>
> -       tqmx86_gpio_set(chip, offset, value);
>         return 0;
>  }
>
>  static int tqmx86_gpio_get_direction(struct gpio_chip *chip,
>                                      unsigned int offset)
>  {
> -       if (TQMX86_DIR_INPUT_MASK & BIT(offset))
> -               return GPIO_LINE_DIRECTION_IN;
> +       struct tqmx86_gpio_data *gpio = gpiochip_get_data(chip);
> +       u8 val;
> +
> +       val = tqmx86_gpio_read(gpio, TQMX86_GPIODD);
> +
> +       if (val & BIT(offset))
> +               return GPIO_LINE_DIRECTION_OUT;
>
> -       return GPIO_LINE_DIRECTION_OUT;
> +       return GPIO_LINE_DIRECTION_IN;
>  }
>
>  static void tqmx86_gpio_irq_config(struct tqmx86_gpio_data *gpio, int hwirq)
> --
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