soc/intel/apollolake: Avoid UART BAR relocation at ramstage

UART bar gets overwritten during resource allocation stage. As result
the serial driver ends up using stale BAR so serial output does not
work. This driver simply tells resource allocator not to change BAR
of UART device.

Change-Id: I81f4f04089106c80bea97f0bbaba890df00c8ac5
Signed-off-by: Andrey Petrov <andrey.petrov@intel.com>
Reviewed-on: https://review.coreboot.org/13997
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins)

src/soc/intel/apollolake/Makefile.inc

@@ -32,6 +32,7 @@ ramstage-y += gpio.c
 ramstage-$(CONFIG_SOC_UART_DEBUG) += uart_early.c
 ramstage-y += memmap.c
 ramstage-y += mmap_boot.c
+ramstage-y += uart.c
 
 CPPFLAGS_common += -I$(src)/soc/intel/apollolake/include
 

src/soc/intel/apollolake/uart.c

@@ -0,0 +1,56 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2015 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.
+ */
+
+/*
+ * The sole purpose of this driver is to avoid BAR to be changed during
+ * resource allocation. Since configuration space is just 32 bytes it
+ * shouldn't cause any fragmentation.
+ */
+
+#include <console/uart.h>
+#include <device/device.h>
+#include <device/pci.h>
+#include <device/pci_ids.h>
+#include <soc/pci_ids.h>
+#include <soc/pci_devs.h>
+
+static void aplk_uart_read_resources(struct device *dev)
+{
+	pci_dev_read_resources(dev);
+
+	if ((IS_ENABLED(CONFIG_SOC_UART_DEBUG) &&
+	    dev->path.pci.devfn == _LPSS_PCI_DEVFN(UART,
+						CONFIG_UART_FOR_CONSOLE))) {
+		/* will override existing resource. */
+		fixed_mem_resource(dev, PCI_BASE_ADDRESS_0,
+				CONFIG_CONSOLE_UART_BASE_ADDRESS >> 10, 4, 0);
+	}
+}
+
+static struct device_operations uart_ops = {
+	.read_resources   = aplk_uart_read_resources,
+	.set_resources    = DEVICE_NOOP,
+	.enable_resources = DEVICE_NOOP,
+	.init             = pci_dev_init,
+	.enable           = DEVICE_NOOP
+};
+
+static const unsigned short uart_ids[] = {
+	PCI_DEVICE_ID_APOLLOLAKE_UART0, PCI_DEVICE_ID_APOLLOLAKE_UART1,
+	PCI_DEVICE_ID_APOLLOLAKE_UART2, PCI_DEVICE_ID_APOLLOLAKE_UART3,
+	0
+};
+
+static const struct pci_driver uart_driver __pci_driver = {
+	.ops     = &uart_ops,
+	.vendor  = PCI_VENDOR_ID_INTEL,
+	.devices = uart_ids
+};