pinctrl: mediatek: paris: Rework support for PIN_CONFIG_{INPUT,OUTPUT}_ENABLE

There is a misinterpretation of some of the PIN_CONFIG_* options in this
driver library. PIN_CONFIG_OUTPUT_ENABLE should refer to a buffer or
switch in the output direction of the electrical path. The MediaTek
hardware does not have such a thing. The driver incorrectly maps this
option to the GPIO function's direction.

Likewise, PIN_CONFIG_INPUT_ENABLE should refer to a buffer or switch in
the input direction. The hardware does have such a mechanism, and is
mapped to the IES bit. The driver however sets the direction in addition
to the IES bit, which is incorrect. On readback, the IES bit isn't even
considered.

Ironically, the driver does not support readback for PIN_CONFIG_OUTPUT,
while its readback of PIN_CONFIG_{INPUT,OUTPUT}_ENABLE is what it should
be doing for PIN_CONFIG_OUTPUT.

Rework support for these three options, so that PIN_CONFIG_OUTPUT_ENABLE
is completely removed, PIN_CONFIG_INPUT_ENABLE is only linked to the IES
bit, and PIN_CONFIG_OUTPUT is linked to the GPIO function's direction
and output level.

Fixes: 80525098 ("pinctrl: mediatek: add pinctrl-paris that implements the vendor dt-bindings")
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Message-ID: <20240327091336.3434141-3-wenst@chromium.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/mediatek/pinctrl-paris.c

@@ -165,20 +165,21 @@ static int mtk_pinconf_get(struct pinctrl_dev *pctldev,
 		err = mtk_hw_get_value(hw, desc, PINCTRL_PIN_REG_SR, &ret);
 		break;
 	case PIN_CONFIG_INPUT_ENABLE:
-	case PIN_CONFIG_OUTPUT_ENABLE:
+		err = mtk_hw_get_value(hw, desc, PINCTRL_PIN_REG_IES, &ret);
+		if (!ret)
+			err = -EINVAL;
+		break;
+	case PIN_CONFIG_OUTPUT:
 		err = mtk_hw_get_value(hw, desc, PINCTRL_PIN_REG_DIR, &ret);
 		if (err)
 			break;
-		/*     CONFIG     Current direction return value
-		 * -------------  ----------------- ----------------------
-		 * OUTPUT_ENABLE       output       1 (= HW value)
-		 *                     input        0 (= HW value)
-		 * INPUT_ENABLE        output       0 (= reverse HW value)
-		 *                     input        1 (= reverse HW value)
-		 */
-		if (param == PIN_CONFIG_INPUT_ENABLE)
-			ret = !ret;
 
+		if (!ret) {
+			err = -EINVAL;
+			break;
+		}
+
+		err = mtk_hw_get_value(hw, desc, PINCTRL_PIN_REG_DO, &ret);
 		break;
 	case PIN_CONFIG_INPUT_SCHMITT_ENABLE:
 		err = mtk_hw_get_value(hw, desc, PINCTRL_PIN_REG_DIR, &ret);
@@ -283,26 +284,9 @@ static int mtk_pinconf_set(struct pinctrl_dev *pctldev, unsigned int pin,
 			break;
 		err = hw->soc->bias_set_combo(hw, desc, 0, arg);
 		break;
-	case PIN_CONFIG_OUTPUT_ENABLE:
-		err = mtk_hw_set_value(hw, desc, PINCTRL_PIN_REG_SMT,
-				       MTK_DISABLE);
-		/* Keep set direction to consider the case that a GPIO pin
-		 *  does not have SMT control
-		 */
-		if (err != -ENOTSUPP)
-			break;
-
-		err = mtk_hw_set_value(hw, desc, PINCTRL_PIN_REG_DIR,
-				       MTK_OUTPUT);
-		break;
 	case PIN_CONFIG_INPUT_ENABLE:
 		/* regard all non-zero value as enable */
 		err = mtk_hw_set_value(hw, desc, PINCTRL_PIN_REG_IES, !!arg);
-		if (err)
-			break;
-
-		err = mtk_hw_set_value(hw, desc, PINCTRL_PIN_REG_DIR,
-				       MTK_INPUT);
 		break;
 	case PIN_CONFIG_SLEW_RATE:
 		/* regard all non-zero value as enable */