timer: Add generic udelay() implementation

Add GENERIC_UDELAY Kconfig option so that a generic
udelay() implementation is provided utilizing the
monotonic timer. That way each board/chipset doesn't
need to duplicate the same udelay(). Additionally,
assume that GENERIC_UDELAY implies init_timer()
is not required.

BUG=None
BRANCH=None
TEST=Built nyan, ryu, and rambi. May need help testing.

Change-Id: I7f511a2324b5aa5d1b2959f4519be85a6a7360e8
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 1a85fbcad778933d13eaef545135abe7e4de46ed
Original-Change-Id: Idd26de19eefc91ee3b0ceddfb1bc2152e19fd8ab
Original-Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/219719
Original-Reviewed-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: http://review.coreboot.org/9334
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

1 files changed, 42 insertions, 0 deletions

diff --git a/src/lib/timer.c b/src/lib/timer.c
new file mode 100644
index 0000000000..a2edc5c96d
--- /dev/null
+++ b/src/lib/timer.c
@@ -0,0 +1,42 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2014 Google Inc.
+ *
+ * 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; version 2 of the License.
+ *
+ * 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <console/console.h>
+#include <timer.h>
+#include <delay.h>
+#include <thread.h>
+
+void udelay(unsigned usec)
+{
+	struct stopwatch sw;
+
+	/*
+	 * As the timer granularity is in microseconds pad the
+	 * requested delay by one to get at least >= requested usec delay.
+	 */
+	usec += 1;
+
+	if (!thread_yield_microseconds(usec))
+		return;
+
+	stopwatch_init_usecs_expire(&sw, usec);
+
+	while (!stopwatch_expired(&sw))
+		;
+}