From: Gabriel Ganne <gabriel.ganne@enea.com>
Date: Mon, 20 Mar 2017 14:13:02 +0000 (+0100)
Subject: armv8 - fix os_cpu_clock_frequency for armv8
X-Git-Tag: v17.04-rc1~16
X-Git-Url: https://gerrit.fd.io/r/gitweb?a=commitdiff_plain;h=1dc2f9284e5b5eb8b300d63cdb8f74ee36cdecb0;p=vpp.git

armv8 - fix os_cpu_clock_frequency for armv8

System timer of ARMv8 runs at a different frequency than the CPU's.
The frequency is fixed, typically in the range 1-50MHz.  It can be
read at CNTFRQ special register.

Change-Id: I6a21a6a9e2df783559df0caec63d5525c2258227
Signed-off-by: Gabriel Ganne <gabriel.ganne@enea.com>
---

diff --git a/src/vppinfra/time.c b/src/vppinfra/time.c
index 2bdb9da4b39..168d7375915 100644
--- a/src/vppinfra/time.c
+++ b/src/vppinfra/time.c
@@ -147,6 +147,12 @@ os_cpu_clock_frequency (void)
   if (clib_cpu_supports_invariant_tsc ())
     return estimate_clock_frequency (1e-3);
 
+#if defined (__aarch64__)
+  u64 tsc;
+  asm volatile ("mrs %0, CNTFRQ_EL0":"=r" (tsc));
+  return (f64) tsc;
+#endif
+
   /* First try /sys version. */
   cpu_freq = clock_frequency_from_sys_filesystem ();
   if (cpu_freq != 0)