x86: Add TSC timer

This timer runs at a rate that can be calculated, well over 100MHz. It is
ideal for accurate timing and does not need interrupt servicing.

Tidy up some old broken and unneeded implementations at the same time.

To provide a consistent view of boot time, we use the same time
base as coreboot. Use the base timestamp supplied by coreboot
as U-Boot's base time.

Signed-off-by: Simon Glass <sjg@chromium.org>base
Signed-off-by: Simon Glass <sjg@chromium.org>

2 files changed, 104 insertions, 0 deletions

diff --git a/arch/x86/lib/Makefile b/arch/x86/lib/Makefile
index 962593d..0bc8c2f 100644
--- a/arch/x86/lib/Makefile
+++ b/arch/x86/lib/Makefile
@@ -37,6 +37,7 @@ COBJS-y	+= relocate.o
 COBJS-y += physmem.o
 COBJS-y	+= string.o
 COBJS-$(CONFIG_SYS_X86_ISR_TIMER)	+= timer.o
+COBJS-$(CONFIG_SYS_X86_TSC_TIMER)	+= tsc_timer.o
 COBJS-$(CONFIG_VIDEO_VGA)	+= video.o
 COBJS-$(CONFIG_CMD_ZBOOT)	+= zimage.o
 
diff --git a/arch/x86/lib/tsc_timer.c b/arch/x86/lib/tsc_timer.c
new file mode 100644
index 0000000..d931e5f
--- /dev/null
+++ b/arch/x86/lib/tsc_timer.c
@@ -0,0 +1,103 @@
+/*
+ * Copyright (c) 2012 The Chromium OS Authors.
+ *
+ * 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.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <malloc.h>
+#include <asm/io.h>
+#include <asm/i8254.h>
+#include <asm/ibmpc.h>
+#include <asm/msr.h>
+#include <asm/u-boot-x86.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+void timer_set_base(u64 base)
+{
+	gd->arch.tsc_base = base;
+}
+
+/*
+ * Get the number of CPU time counter ticks since it was read first time after
+ * restart. This yields a free running counter guaranteed to take almost 6
+ * years to wrap around even at 100GHz clock rate.
+ */
+u64 get_ticks(void)
+{
+	u64 now_tick = rdtsc();
+
+	/* We assume that 0 means the base hasn't been set yet */
+	if (!gd->arch.tsc_base)
+		panic("No tick base available");
+	return now_tick - gd->arch.tsc_base;
+}
+
+#define PLATFORM_INFO_MSR 0xce
+
+/* Get the speed of the TSC timer in MHz */
+unsigned long get_tbclk_mhz(void)
+{
+	u32 ratio;
+	u64 platform_info = native_read_msr(PLATFORM_INFO_MSR);
+
+	/* 100MHz times Max Non Turbo ratio */
+	ratio = (platform_info >> 8) & 0xff;
+	return 100 * ratio;
+}
+
+unsigned long get_tbclk(void)
+{
+	return get_tbclk_mhz() * 1000 * 1000;
+}
+
+static ulong get_ms_timer(void)
+{
+	return (get_ticks() * 1000) / get_tbclk();
+}
+
+ulong get_timer(ulong base)
+{
+	return get_ms_timer() - base;
+}
+
+ulong timer_get_us(void)
+{
+	return get_ticks() / get_tbclk_mhz();
+}
+
+ulong timer_get_boot_us(void)
+{
+	return timer_get_us();
+}
+
+void __udelay(unsigned long usec)
+{
+	u64 now = get_ticks();
+	u64 stop;
+
+	stop = now + usec * get_tbclk_mhz();
+
+	while ((int64_t)(stop - get_ticks()) > 0)
+		;
+}
+
+int timer_init(void)
+{
+	/* Nothing to do here - the timer needs no init */
+	return 0;
+}