sam3x: Add gpio_init convenience function.

include/libopencm3/sam3x/gpio.h

@@ -22,6 +22,19 @@
 
 #include <libopencm3/sam3x/pio.h>
 
+/* flags may be or'd together, but only contain one of
+ * GPOUTPUT, PERIPHA and PERIPHB */
+enum gpio_flags {
+	GPIO_FLAG_GPINPUT = 0,
+	GPIO_FLAG_GPOUTPUT = 1,
+	GPIO_FLAG_PERIPHA = 2,
+	GPIO_FLAG_PERIPHB = 3,
+	GPIO_FLAG_OPEN_DRAIN = 4,
+	GPIO_FLAG_PULL_UP = 8,
+};
+
+void gpio_init(u32 gpioport, u32 pins, enum gpio_flags flags);
+
 static inline void gpio_set(u32 gpioport, u32 gpios)
 {
 	PIO_SODR(gpioport) = gpios;

lib/sam3x/gpio.c

@@ -19,6 +19,40 @@
 
 #include <libopencm3/sam3x/gpio.h>
 
+void gpio_init(u32 port, u32 pins, enum gpio_flags flags)
+{
+	switch (flags & 3) {
+	case GPIO_FLAG_GPINPUT:
+		/* input mode doesn't really exist, so we make a high
+		 * output in open-drain mode
+		 */
+		PIO_SODR(port) = pins;
+		flags |= GPIO_FLAG_OPEN_DRAIN;
+		/* fall through */
+	case GPIO_FLAG_GPOUTPUT:
+		PIO_OER(port) = pins;
+		PIO_PER(port) = pins;
+		break;
+	case GPIO_FLAG_PERIPHA:
+		PIO_ABSR(port) &= ~pins;
+		PIO_PDR(port) = pins;
+		break;
+	case GPIO_FLAG_PERIPHB:
+		PIO_ABSR(port) |= pins;
+		PIO_PDR(port) = pins;
+	}
+
+	if (flags & GPIO_FLAG_OPEN_DRAIN)
+		PIO_MDER(port) = pins;
+	else
+		PIO_MDDR(port) = pins;
+
+	if (flags & GPIO_FLAG_PULL_UP)
+		PIO_PUER(port) = pins;
+	else
+		PIO_PUDR(port) = pins;
+}
+
 void gpio_toggle(u32 gpioport, u32 gpios)
 {
 	u32 odsr = PIO_ODSR(gpioport);