Re: [PATCH 1/3] pinctrl: sunxi: Add support for fetching pinconf settings from hardware

[Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>]

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On Tue, Oct 04, 2016 at 09:51:10AM +0800, Chen-Yu Tsai wrote:
> The sunxi pinctrl driver only caches whatever pinconf setting was last
> set on a given pingroup. This is not particularly helpful, nor is it
> correct.
> 
> Fix this by actually reading the hardware registers and returning
> the correct results or error codes. Also filter out unsupported
> pinconf settings. Since this driver has a peculiar setup of 1 pin
> per group, we can support both pin and pingroup pinconf setting
> read back with the same code. The sunxi_pconf_reg helper and code
> structure is inspired by pinctrl-msm.
> 
> With this done we can also claim to support generic pinconf, by
> setting .is_generic = true in pinconf_ops.
> 
> Signed-off-by: Chen-Yu Tsai <wens-jdAy2FN1RRM@public.gmane.org>
> ---
>  drivers/pinctrl/sunxi/pinctrl-sunxi.c | 85 +++++++++++++++++++++++++++++++++--
>  1 file changed, 82 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pinctrl/sunxi/pinctrl-sunxi.c b/drivers/pinctrl/sunxi/pinctrl-sunxi.c
> index 54455af566ec..609843c9a65c 100644
> --- a/drivers/pinctrl/sunxi/pinctrl-sunxi.c
> +++ b/drivers/pinctrl/sunxi/pinctrl-sunxi.c
> @@ -10,6 +10,7 @@
>   * warranty of any kind, whether express or implied.
>   */
>  
> +#include <dt-bindings/pinctrl/sun4i-a10.h>
>  #include <linux/io.h>
>  #include <linux/clk.h>
>  #include <linux/gpio/driver.h>
> @@ -269,15 +270,91 @@ static const struct pinctrl_ops sunxi_pctrl_ops = {
>  	.get_group_pins		= sunxi_pctrl_get_group_pins,
>  };
>  
> +static int sunxi_pconf_reg(unsigned pin, enum pin_config_param param,
> +			   u32 *offset, u32 *shift, u32 *mask)
> +{
> +	switch (param) {
> +	case PIN_CONFIG_DRIVE_STRENGTH:
> +		*offset = sunxi_dlevel_reg(pin);
> +		*shift = sunxi_dlevel_offset(pin);
> +		*mask = DLEVEL_PINS_MASK;
> +		break;
> +
> +	case PIN_CONFIG_BIAS_PULL_UP:
> +	case PIN_CONFIG_BIAS_PULL_DOWN:
> +	case PIN_CONFIG_BIAS_DISABLE:
> +		*offset = sunxi_pull_reg(pin);
> +		*shift = sunxi_pull_offset(pin);
> +		*mask = PULL_PINS_MASK;
> +		break;
> +
> +	default:
> +		return -ENOTSUPP;
> +	}
> +
> +	return 0;
> +}
> +
> +static int sunxi_pconf_get(struct pinctrl_dev *pctldev, unsigned pin,
> +			   unsigned long *config)
> +{
> +	struct sunxi_pinctrl *pctl = pinctrl_dev_get_drvdata(pctldev);
> +	enum pin_config_param param = pinconf_to_config_param(*config);
> +	u32 offset, shift, mask, val;
> +	u16 arg;
> +	int ret;
> +
> +	pin -= pctl->desc->pin_base;
> +
> +	ret = sunxi_pconf_reg(pin, param, &offset, &shift, &mask);
> +	if (ret < 0)
> +		return ret;
> +
> +	val = (readl(pctl->membase + offset) >> shift) & mask;
> +
> +	switch (pinconf_to_config_param(*config)) {
> +	case PIN_CONFIG_DRIVE_STRENGTH:
> +		arg = (val + 1) * 10;
> +		break;
> +
> +	case PIN_CONFIG_BIAS_PULL_UP:
> +		if (val != SUN4I_PINCTRL_PULL_UP)
> +			return -EINVAL;
> +		arg = 1; /* hardware is weak pull-up */
> +		break;
> +
> +	case PIN_CONFIG_BIAS_PULL_DOWN:
> +		if (val != SUN4I_PINCTRL_PULL_DOWN)
> +			return -EINVAL;
> +		arg = 1; /* hardware is weak pull-down */
> +		break;
> +
> +	case PIN_CONFIG_BIAS_DISABLE:
> +		if (val != SUN4I_PINCTRL_NO_PULL)
> +			return -EINVAL;
> +		arg = 0;
> +		break;
> +
> +	default:
> +		/* sunxi_pconf_reg should catch anything unsupported */
> +		WARN_ON(1);
> +		return -ENOTSUPP;

This should be EINVAL. The operation is supported, but one of the
argument is not valid.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com