gpio: msm: fix get_function return for special pins

The get_function callback wrongly returns 0 for special pins,
return the appropriate pin function by probing into the special
pins data fields to find if the pin is gpio capable.

Fixes: f9bb539460d ("gpio: msm: add support for special pins")
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250401-topic-sm8x50-msm-gpio-special-fixes-v1-1-a1148a02bb16@linaro.org
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>

diff --git a/drivers/gpio/msm_gpio.c b/drivers/gpio/msm_gpio.c
index cea073b..f208eec 100644 (file)
--- a/drivers/gpio/msm_gpio.c
+++ b/drivers/gpio/msm_gpio.c
@@ -192,13 +192,41 @@ static int msm_gpio_get_value(struct udevice *dev, unsigned int gpio)
        return !!(readl(priv->base + GPIO_IN_OUT_REG(dev, gpio)) >> GPIO_IN);
 }
 
+static int msm_gpio_get_function_special(struct msm_gpio_bank *priv,
+                                        unsigned int gpio)
+{
+       unsigned int offset = gpio - priv->pin_data->special_pins_start;
+       const struct msm_special_pin_data *data;
+
+       if (!priv->pin_data->special_pins_data)
+               return GPIOF_UNKNOWN;
+
+       data = &priv->pin_data->special_pins_data[offset];
+
+       /* No I/O fields, cannot control/read the I/O value */
+       if (!data->io_reg || (data->out_bit >= 31 && data->in_bit >= 31))
+               return GPIOF_FUNC;
+
+       /* No Output-Enable register, cannot control I/O direction */
+       if (!data->ctl_reg || data->oe_bit >= 31) {
+               if (data->out_bit >= 31)
+                       return GPIOF_INPUT;
+               else
+                       return GPIOF_OUTPUT;
+       }
+
+       if (readl(priv->base + data->ctl_reg) & BIT(data->oe_bit))
+               return GPIOF_OUTPUT;
+
+       return GPIOF_INPUT;
+}
+
 static int msm_gpio_get_function(struct udevice *dev, unsigned int gpio)
 {
        struct msm_gpio_bank *priv = dev_get_priv(dev);
 
-       /* Always NOP for special pins, assume they're in the correct state */
        if (qcom_is_special_pin(priv->pin_data, gpio))
-               return 0;
+               return msm_gpio_get_function_special(priv, gpio);
 
        if (readl(priv->base + GPIO_CONFIG_REG(dev, gpio)) & GPIO_OE_ENABLE)
                return GPIOF_OUTPUT;