1 files changed, 60 insertions, 0 deletions
diff --git a/arch/efi/efi/clocksource.c b/arch/efi/efi/clocksource.c
new file mode 100644
index 0000000000..2f33b43cce
--- /dev/null
+++ b/arch/efi/efi/clocksource.c
@@ -0,0 +1,60 @@
+#include <common.h>
+#include <efi.h>
+#include <mach/efi.h>
+#include <clock.h>
+
+#ifdef __x86_64__
+uint64_t ticks_read(void)
+{
+	uint64_t a, d;
+
+	__asm__ volatile ("rdtsc" : "=a" (a), "=d" (d));
+
+	return (d << 32) | a;
+}
+#else
+uint64_t ticks_read(void)
+{
+	uint64_t val;
+
+	__asm__ volatile ("rdtsc" : "=A" (val));
+
+	return val;
+}
+#endif
+
+static uint64_t freq;
+
+/* count TSC ticks during a millisecond delay */
+static uint64_t ticks_freq(void)
+{
+	uint64_t ticks_start, ticks_end;
+
+	ticks_start = ticks_read();
+	BS->stall(1000);
+	ticks_end = ticks_read();
+
+	return (ticks_end - ticks_start) * 1000;
+}
+
+static uint64_t efi_clocksource_read(void)
+{
+	return 1000 * 1000 * ticks_read() / freq;
+}
+
+static struct clocksource cs = {
+	.read   = efi_clocksource_read,
+	.mask   = CLOCKSOURCE_MASK(64),
+	.shift  = 0,
+};
+
+int efi_clocksource_init(void)
+{
+	cs.mult = clocksource_hz2mult(1000 * 1000, cs.shift);
+
+	freq = ticks_freq();
+
+	init_clock(&cs);
+
+	return 0;
+}