dm: gpio: Implement open drain for MPC85XX GPIO

This patch implements the open-drain setting feature for the MPC85XX
GPIO controller.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: York Sun <york.sun@nxp.com>

drivers/gpio/Kconfig

@@ -193,9 +193,9 @@ config MPC85XX_GPIO
 	  configurable to match the actual GPIO count of the SoC (e.g. the
 	  32/32/23 banks of the P1022 SoC).
 
-	  The standard functions of input/output mode, and output value setting
-	  are supported; the open-drain capability of the controller is not
-	  supported yet.
+	  Aside from the standard functions of input/output mode, and output
+	  value setting, the open-drain feature, which can configure individual
+	  GPIOs to work as open-drain outputs, is supported.
 
 	  The driver has been tested on MPC85XX, but it is likely that other
 	  PowerQUICC III devices will work as well.

drivers/gpio/mpc85xx_gpio.c

@@ -73,6 +73,25 @@ static inline void mpc85xx_gpio_set_high(struct ccsr_gpio *base, u32 gpios)
 	setbits_be32(&base->gpdir, gpios);
 }
 
+static inline int mpc85xx_gpio_open_drain_val(struct ccsr_gpio *base, u32 mask)
+{
+	return in_be32(&base->gpodr) & mask;
+}
+
+static inline void mpc85xx_gpio_open_drain_on(struct ccsr_gpio *base, u32
+					      gpios)
+{
+	/* GPODR register 1 -> open drain on */
+	setbits_be32(&base->gpodr, gpios);
+}
+
+static inline void mpc85xx_gpio_open_drain_off(struct ccsr_gpio *base,
+					       u32 gpios)
+{
+	/* GPODR register 0 -> open drain off (actively driven) */
+	clrbits_be32(&base->gpodr, gpios);
+}
+
 static int mpc85xx_gpio_direction_input(struct udevice *dev, unsigned gpio)
 {
 	struct mpc85xx_gpio_data *data = dev_get_priv(dev);
@@ -115,6 +134,26 @@ static int mpc85xx_gpio_get_value(struct udevice *dev, unsigned gpio)
 	}
 }
 
+static int mpc85xx_gpio_get_open_drain(struct udevice *dev, unsigned gpio)
+{
+	struct mpc85xx_gpio_data *data = dev_get_priv(dev);
+
+	return !!mpc85xx_gpio_open_drain_val(data->base, gpio_mask(gpio));
+}
+
+static int mpc85xx_gpio_set_open_drain(struct udevice *dev, unsigned gpio,
+				       int value)
+{
+	struct mpc85xx_gpio_data *data = dev_get_priv(dev);
+
+	if (value) {
+		mpc85xx_gpio_open_drain_on(data->base, gpio_mask(gpio));
+	} else {
+		mpc85xx_gpio_open_drain_off(data->base, gpio_mask(gpio));
+	}
+	return 0;
+}
+
 static int mpc85xx_gpio_get_function(struct udevice *dev, unsigned gpio)
 {
 	struct mpc85xx_gpio_data *data = dev_get_priv(dev);
@@ -168,6 +207,8 @@ static const struct dm_gpio_ops gpio_mpc85xx_ops = {
 	.direction_output	= mpc85xx_gpio_direction_output,
 	.get_value		= mpc85xx_gpio_get_value,
 	.set_value		= mpc85xx_gpio_set_value,
+	.get_open_drain		= mpc85xx_gpio_get_open_drain,
+	.set_open_drain		= mpc85xx_gpio_set_open_drain,
 	.get_function 		= mpc85xx_gpio_get_function,
 };