boards: nrf52840_pca10090: Convert to use the new GPIO API

Update the code configuring pins that control the routing of certain
lines on the board, to take advantage of the introduced possibility
of configuring a pin as output with specified initial state.

Additionally, use `gpio_pin_get_raw` instead of `gpio_pin_get` for
checking the reset pin state, to save a few bytes in flash.

Signed-off-by: Andrzej Głąbek <[email protected]>

Author: anangl

boards/arm/nrf52840_pca10090/board.c

@@ -176,20 +176,16 @@ static int pins_configure(struct device *port, const struct pin_config cfg[],
 {
 	int err;
 
-	/* Write to the pins before configuring them as output,
-	 * to make sure we are driving them to the correct level
-	 * right after they are configured.
-	 */
 	for (size_t i = 0; i < pins; i++) {
-		/* The swiches on the board are active low, so we need
-		 * to negate the IS_ENABLED() value from the tables.
+		/* A given pin controlling the switch needs to be driven
+		 * to the low state to activate the routing indicated by
+		 * the corresponding IS_ENABLED() macro in the table,
+		 * so configure the pin as output with the proper initial
+		 * state.
 		 */
-		err = gpio_pin_set(port, cfg[i].pin, !cfg[i].val);
-		if (err) {
-			return cfg[i].pin;
-		}
-
-		err = gpio_pin_configure(port, cfg[i].pin, GPIO_OUTPUT);
+		u32_t flag = (cfg[i].val ? GPIO_OUTPUT_LOW
+					 : GPIO_OUTPUT_HIGH);
+		err = gpio_pin_configure(port, cfg[i].pin, flag);
 		if (err) {
 			return cfg[i].pin;
 		}
@@ -218,7 +214,7 @@ static void reset_pin_wait_low(struct device *port, u32_t pin)
 
 	/* Wait until the pin is pulled low */
 	do {
-		val = gpio_pin_get(port, pin);
+		val = gpio_pin_get_raw(port, pin);
 	} while (val > 0);
 }