soc/apollolake: Add early serial driver for BOOTBLOCK_CONSOLE

Early UART driver is for bootblock and romstage. It is supposed to be used
when BOOTBLOCK_CONSOLE is enabled. This also adds few configuration bits
in bootblock requiered for serial to be set up.

Change-Id: I15520d566f107797e68d618885d4379e73d0fa45
Signed-off-by: Andrey Petrov <andrey.petrov@intel.com>
Reviewed-on: https://review.coreboot.org/13677
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

1 files changed, 20 insertions, 0 deletions

diff --git a/src/soc/intel/apollolake/tsc_freq.c b/src/soc/intel/apollolake/tsc_freq.c
new file mode 100644
index 0000000000..b6320eda8f
--- /dev/null
+++ b/src/soc/intel/apollolake/tsc_freq.c
@@ -0,0 +1,20 @@
+/*
+ * 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.
+ */
+
+#include <cpu/x86/msr.h>
+#include <cpu/x86/tsc.h>
+#include <soc/cpu.h>
+
+unsigned long tsc_freq_mhz(void)
+{
+    msr_t msr = rdmsr(MSR_PLATFORM_INFO);
+    return (BASE_CLOCK_MHZ * ((msr.lo >> 8) & 0xff));
+}