soc/intel/cannonlake: Add UART initialization

Cannonlake has built-in UART driver as part of LPSS block. However port
mapped decoders are in use as well.

Change-Id: I9f209bf29c1748c5beea31bc6b31cb07a1e14195
Signed-off-by: Andrey Petrov <andrey.petrov@intel.com>
Reviewed-on: https://review.coreboot.org/20063
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/soc/intel/cannonlake/uart.c

@@ -0,0 +1,67 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2017 Intel Corporation
+ *
+ * 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; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <assert.h>
+#include <console/uart.h>
+#include <device/pci_def.h>
+#include <intelblocks/gpio.h>
+#include <intelblocks/lpss.h>
+#include <intelblocks/pcr.h>
+#include <intelblocks/uart.h>
+#include <soc/pch.h>
+#include <soc/pci_devs.h>
+#include <soc/pcr_ids.h>
+#include <soc/iomap.h>
+
+/* Clock divider parameters for 115200 baud rate */
+#define CLK_M_VAL	0x30
+#define CLK_N_VAL	0xc35
+
+static const struct port {
+	struct pad_config pads[2]; /* just TX and RX */
+	device_t dev;
+} uart_ports[] = {
+	{.dev = PCH_DEV_UART0,
+	 .pads = { PAD_CFG_NF(GPP_C8, NONE, DEEP, NF1), /* RX */
+		   PAD_CFG_NF(GPP_C9, NONE, DEEP, NF1)} /* TX */
+	},
+	{.dev = PCH_DEV_UART1,
+	 .pads = { PAD_CFG_NF(GPP_C12, NONE, DEEP, NF1), /* RX */
+		   PAD_CFG_NF(GPP_C13, NONE, DEEP, NF1)} /* TX */
+	},
+	{.dev = PCH_DEV_UART2,
+	 .pads = { PAD_CFG_NF(GPP_C20, NONE, DEEP, NF1), /* RX */
+		   PAD_CFG_NF(GPP_C21, NONE, DEEP, NF1)} /* TX */
+	}
+};
+
+void pch_uart_init(void)
+{
+	uintptr_t base;
+	const struct port *p;
+
+	assert(CONFIG_UART_FOR_CONSOLE < ARRAY_SIZE(uart_ports));
+	p = &uart_ports[CONFIG_UART_FOR_CONSOLE];
+	base = uart_platform_base(CONFIG_UART_FOR_CONSOLE);
+
+	uart_common_init(p->dev, base, CLK_M_VAL, CLK_N_VAL);
+	gpio_configure_pads(p->pads, ARRAY_SIZE(p->pads));
+}
+
+uintptr_t uart_platform_base(int idx)
+{
+	/* We can only have one serial console at a time */
+	return UART_DEBUG_BASE_ADDRESS;
+}