soc/apollolake: Add minimal GPIO driver

This adds the minimal functionality needed to configure SoC pads.

Change-Id: I2e2268eee2b8c822b42a48a95604b0fab86c9833
Signed-off-by: Andrey Petrov <andrey.petrov@intel.com>
Reviewed-on: https://review.coreboot.org/13676
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins)

src/soc/intel/apollolake/gpio.c

@@ -0,0 +1,60 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2015 Intel Corp.
+ * (Written by Alexandru Gagniuc <alexandrux.gagniuc@intel.com> for Intel Corp.)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <soc/gpio.h>
+#include <soc/iosf.h>
+
+/* This list must be in order, from highest pad numbers, to lowest pad numbers*/
+static const struct pad_community {
+	uint16_t first_pad;
+	uint8_t port;
+} gpio_communities[] = {
+	{
+		.port = GPIO_SOUTHWEST,
+		.first_pad = SW_OFFSET,
+	}, {
+		.port = GPIO_WEST,
+		.first_pad = W_OFFSET,
+	}, {
+		.port = GPIO_NORTHWEST,
+		.first_pad = NW_OFFSET,
+	}, {
+		.port = GPIO_NORTH,
+		.first_pad = 0,
+	}
+};
+
+static const struct pad_community *gpio_get_community(uint16_t pad)
+{
+	const struct pad_community *map = gpio_communities;
+
+	while (map->first_pad > pad)
+		map++;
+
+	return map;
+}
+
+void gpio_configure_pad(const struct pad_config *cfg)
+{
+	const struct pad_community *comm = gpio_get_community(cfg->pad);
+	uint16_t config_offset = PAD_CFG_OFFSET(cfg->pad - comm->first_pad);
+	iosf_write(comm->port, config_offset, cfg->config0);
+	iosf_write(comm->port, config_offset + sizeof(uint32_t), cfg->config1);
+}
+
+void gpio_configure_pads(const struct pad_config *cfg, size_t num_pads)
+{
+	uint32_t i;
+
+	for (i = 0; i < num_pads; i++)
+		gpio_configure_pad(cfg + i);
+}