exynos: Add support for the DisplayPort hotplug detect

Allow this function to be selected using the pinmux API.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/cpu/armv7/exynos/pinmux.c b/arch/arm/cpu/armv7/exynos/pinmux.c
index be43e22..e97cb37 100644
--- a/arch/arm/cpu/armv7/exynos/pinmux.c
+++ b/arch/arm/cpu/armv7/exynos/pinmux.c
@@ -496,6 +496,16 @@
 	case PERIPH_ID_SPI4:
 		exynos5_spi_config(peripheral);
 		break;
+	case PERIPH_ID_DPHPD:
+		/* Set Hotplug detect for DP */
+		gpio_cfg_pin(EXYNOS5_GPIO_X07, S5P_GPIO_FUNC(0x3));
+
+		/*
+		 * Hotplug detect should have an external pullup; disable the
+		 * internal pulldown so they don't fight.
+		 */
+		gpio_set_pull(EXYNOS5_GPIO_X07, S5P_GPIO_PULL_NONE);
+		break;
 	default:
 		debug("%s: invalid peripheral %d", __func__, peripheral);
 		return -1;