intel/fsp_broadwell_de: Add timestamp functionality

Add a little code to enable timestamps on FSP based implementation
of Broadwell-DE. I have tested it by reading back the timestamps
with cbmem utility once the board has booted into Lubuntu.

Change-Id: Idaa65a22a00382bf0c37acf2f5a1e07c6b1b42d9
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/21932
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/soc/intel/fsp_broadwell_de/Makefile.inc

@@ -16,6 +16,7 @@ ramstage-y += cpu.c
 ramstage-y += chip.c
 ramstage-y += northcluster.c
 ramstage-y += ramstage.c
+ramstage-y += tsc_freq.c
 romstage-y += memmap.c
 ramstage-y += memmap.c
 ramstage-y += southcluster.c
@@ -24,11 +25,13 @@ ramstage-y += reset.c
 ramstage-y += acpi.c
 ramstage-y += smbus_common.c
 ramstage-y += smbus.c
+romstage-y += tsc_freq.c
 ramstage-y += smi.c
 ramstage-$(CONFIG_HAVE_SMI_HANDLER) += smmrelocate.c
 ramstage-$(CONFIG_HAVE_SMI_HANDLER) += pmutil.c
 smm-$(CONFIG_HAVE_SMI_HANDLER) += pmutil.c
 smm-$(CONFIG_HAVE_SMI_HANDLER) += smihandler.c
+smm-$(CONFIG_HAVE_SMI_HANDLER) += tsc_freq.c
 
 CPPFLAGS_common += -I$(src)/soc/intel/fsp_broadwell_de/include
 CPPFLAGS_common += -I$(src)/soc/intel/fsp_broadwell_de/fsp

src/soc/intel/fsp_broadwell_de/include/soc/broadwell_de.h

@@ -26,4 +26,7 @@
 #define TSEG_BASE		0xa8	/* TSEG base */
 #define TSEG_LIMIT		0xac	/* TSEG limit */
 
+/* CPU bus clock is fixed at 100MHz */
+#define CPU_BCLK		100
+
 #endif /* _SOC_BROADWELL_DE_H_ */

src/soc/intel/fsp_broadwell_de/tsc_freq.c

@@ -0,0 +1,28 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2014 Google Inc.
+ *
+ * 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 <stdint.h>
+#include <cpu/x86/msr.h>
+#include <cpu/x86/tsc.h>
+#include <soc/msr.h>
+#include <soc/broadwell_de.h>
+
+unsigned long tsc_freq_mhz(void)
+{
+	msr_t platform_info;
+
+	platform_info = rdmsr(MSR_PLATFORM_INFO);
+	return CPU_BCLK * ((platform_info.lo >> 8) & 0xff);
+}