arm64: Generic timers support

This patch adds support for the ARM generic timers with A64 instructions
for accessing the timer registers. It uses the physical counter as the
clock source and the virtual counter as sched_clock.

The timer frequency can be specified via DT or read from the CNTFRQ_EL0
register. The physical counter is also accessible from user space
allowing fast gettimeofday() implementation.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 29 insertions, 0 deletions

diff --git a/arch/arm64/include/asm/timex.h b/arch/arm64/include/asm/timex.h
new file mode 100644
index 000000000000..b24a31a7e2c9
--- /dev/null
+++ b/arch/arm64/include/asm/timex.h
@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_TIMEX_H
+#define __ASM_TIMEX_H
+
+/*
+ * Use the current timer as a cycle counter since this is what we use for
+ * the delay loop.
+ */
+#define get_cycles()	({ cycles_t c; read_current_timer(&c); c; })
+
+#include <asm-generic/timex.h>
+
+#define ARCH_HAS_READ_CURRENT_TIMER
+
+#endif