CR50: refactor debug_printf() for use as a library function

loader/key_ladder.c depends on debug_printf().  Refactor
the printf function so that key_ladder.c need not depend
on main.c.

This change being made in preparation for a future
change which introduces a dependency between RW and
key_ladder.o

BRANCH=none
BUG=chrome-os-partner:43025,chrome-os-partner:47524
TEST=build succeeds

Change-Id: I5c9bf7bd6dd9f76ab6410e6e797973bdb072ec16
Signed-off-by: nagendra modadugu <ngm@google.com>
Reviewed-on: https://chromium-review.googlesource.com/351760
Commit-Ready: Nagendra Modadugu <ngm@google.com>
Tested-by: Nagendra Modadugu <ngm@google.com>
Reviewed-by: Bill Richardson <wfrichar@chromium.org>

3 files changed, 29 insertions, 18 deletions

diff --git a/chip/g/build.mk b/chip/g/build.mk
index 12c3c9079d..d7e7b02cc3 100644
--- a/chip/g/build.mk
+++ b/chip/g/build.mk
@@ -78,6 +78,7 @@ ifneq ($(CONFIG_CUSTOMIZED_RO),)
 custom-ro_objs-y  = chip/g/clock.o
 custom-ro_objs-y += chip/g/dcrypto/sha256.o
 custom-ro_objs-y += chip/g/loader/key_ladder.o
+custom-ro_objs-y += chip/g/loader/debug_printf.o
 custom-ro_objs-y += chip/g/loader/launch.o
 custom-ro_objs-y += chip/g/loader/main.o
 custom-ro_objs-y += chip/g/loader/rom_flash.o
diff --git a/chip/g/loader/debug_printf.c b/chip/g/loader/debug_printf.c
new file mode 100644
index 0000000000..4d7e67b7ec
--- /dev/null
+++ b/chip/g/loader/debug_printf.c
@@ -0,0 +1,28 @@
+/* Copyright 2016 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+#include "debug_printf.h"
+
+#include "printf.h"
+#include "uart.h"
+
+#include "stddef.h"
+
+static int printchar(void *context, int c)
+{
+	if (c == '\n')
+		uart_write_char('\r');
+	uart_write_char(c);
+
+	return 0;
+}
+
+void debug_printf(const char *format, ...)
+{
+	va_list args;
+
+	va_start(args, format);
+	vfnprintf(printchar, NULL, format, args);
+	va_end(args);
+}
diff --git a/chip/g/loader/main.c b/chip/g/loader/main.c
index 985aa34a19..7381e52471 100644
--- a/chip/g/loader/main.c
+++ b/chip/g/loader/main.c
@@ -131,21 +131,3 @@ void interrupt_disable(void)
 {
 	asm("cpsid i");
 }
-
-static int printchar(void *context, int c)
-{
-	if (c == '\n')
-		uart_write_char('\r');
-	uart_write_char(c);
-
-	return 0;
-}
-
-void debug_printf(const char *format, ...)
-{
-	va_list args;
-
-	va_start(args, format);
-	vfnprintf(printchar, NULL, format, args);
-	va_end(args);
-}