RE: [PATCH] pinctrl: samsung: Add support for pull-up and pull-down

["Alim Akhtar" <alim.akhtar@samsung.com>]

Hi Vishnu,

> -----Original Message-----
> From: Vishnu Reddy <vishnu.reddy@samsung.com>
> Sent: Wednesday, May 29, 2024 12:30 PM
> To: krzk@kernel.org; s.nawrocki@samsung.com; alim.akhtar@samsung.com;
> linus.walleij@linaro.org
> Cc: linux-arm-kernel@lists.infradead.org; linux-samsung-soc@vger.kernel.org;
> linux-gpio@vger.kernel.org; linux-kernel@vger.kernel.org;
> pankaj.dubey@samsung.com; ravi.patel@samsung.com
> Subject: [PATCH] pinctrl: samsung: Add support for pull-up and pull-down
> 
> gpiolib framework has the implementation of setting up the PUD configuration
> for GPIO pins but there is no driver support.
> 
> Add support to handle the PUD configuration request from the userspace in
> samsung pinctrl driver.
> 
> Signed-off-by: Vishnu Reddy <vishnu.reddy@samsung.com>
> ---
>  drivers/pinctrl/samsung/pinctrl-samsung.c | 51 +++++++++++++++++++++++
> drivers/pinctrl/samsung/pinctrl-samsung.h |  7 ++++
>  2 files changed, 58 insertions(+)
> 
> diff --git a/drivers/pinctrl/samsung/pinctrl-samsung.c
> b/drivers/pinctrl/samsung/pinctrl-samsung.c
> index ed07e23e0912..a4b6eea5e168 100644
> --- a/drivers/pinctrl/samsung/pinctrl-samsung.c
> +++ b/drivers/pinctrl/samsung/pinctrl-samsung.c
> @@ -939,6 +939,56 @@ static int samsung_pinctrl_unregister(struct
> platform_device *pdev,
>  	return 0;
>  }
> 
> +/*
> + * samsung_gpio_set_pud will enable or disable the pull-down and
> + * pull-up for the gpio pins in the PUD register.
> + */
> +static void samsung_gpio_set_pud(struct gpio_chip *gc, unsigned int offset,
> +				 unsigned int value)
> +{
> +	struct samsung_pin_bank *bank = gpiochip_get_data(gc);
> +	const struct samsung_pin_bank_type *type = bank->type;
> +	void __iomem *reg;
> +	unsigned int data;
> +
> +	reg = bank->pctl_base + bank->pctl_offset;
> +	data = readl(reg + type->reg_offset[PINCFG_TYPE_PUD]);
> +	data &= ~(0xf << (offset * 4));
For the mask, you can use "type->fld_width" as that is more generic and will work for all SoC
I didn’t get, why you are multiplying offset with 4? Is this true for all SoC?

> +	data |= value << (offset * 4);
> +	writel(data, reg + type->reg_offset[PINCFG_TYPE_PUD]);
> +}
> +
> +/*
> + * samsung_gpio_set_config will identify the type of PUD config based
> + * on the gpiolib request to enable or disable the PUD configuration.
> + */
> +static int samsung_gpio_set_config(struct gpio_chip *gc, unsigned int offset,
> +				   unsigned long config)
> +{
> +	struct samsung_pin_bank *bank = gpiochip_get_data(gc);
> +	unsigned long flags;
> +	unsigned int value = 0;
> +
> +	switch (pinconf_to_config_param(config)) {
> +	case PIN_CONFIG_BIAS_DISABLE:
> +		value = DISABLE_PIN_PULL_UP_DOWN;
> +		break;
> +	case PIN_CONFIG_BIAS_PULL_DOWN:
> +		value = ENABLE_PIN_PULL_DOWN;
> +		break;
> +	case PIN_CONFIG_BIAS_PULL_UP:
> +		value = ENABLE_PIN_PULL_UP;
> +		break;
> +	default:
> +		return -ENOTSUPP;
> +	}
> +
> +	raw_spin_lock_irqsave(&bank->slock, flags);
> +	samsung_gpio_set_pud(gc, offset, value);
> +	raw_spin_unlock_irqrestore(&bank->slock, flags);
> +	return 0;
> +}
> +
>  static const struct gpio_chip samsung_gpiolib_chip = {
>  	.request = gpiochip_generic_request,
>  	.free = gpiochip_generic_free,
> @@ -948,6 +998,7 @@ static const struct gpio_chip samsung_gpiolib_chip = {
>  	.direction_output = samsung_gpio_direction_output,
>  	.to_irq = samsung_gpio_to_irq,
>  	.add_pin_ranges = samsung_add_pin_ranges,
> +	.set_config = samsung_gpio_set_config,
>  	.owner = THIS_MODULE,
>  };
> 
> diff --git a/drivers/pinctrl/samsung/pinctrl-samsung.h
> b/drivers/pinctrl/samsung/pinctrl-samsung.h
> index ab791afaabf5..23b70ddcaccc 100644
> --- a/drivers/pinctrl/samsung/pinctrl-samsung.h
> +++ b/drivers/pinctrl/samsung/pinctrl-samsung.h
> @@ -61,6 +61,13 @@ enum pincfg_type {
>  #define PIN_CON_FUNC_INPUT		0x0
>  #define PIN_CON_FUNC_OUTPUT		0x1
> 
> +/*
> + * Values for the pin PUD register.
> + */
> +#define DISABLE_PIN_PULL_UP_DOWN	0x0
> +#define ENABLE_PIN_PULL_DOWN		0x1
> +#define ENABLE_PIN_PULL_UP		0x3
Use consistent naming conventions as per this file, so 
PIN_PUD_PULL_UP_DOWN_DISABLE
PIN_PUD_PULL_DOWN_ENABLE
PIN_PUD_PULL_UP_ENABLE

> +
>  /**
>   * enum eint_type - possible external interrupt types.
>   * @EINT_TYPE_NONE: bank does not support external interrupts
> --
> 2.17.1