From 493a4c8af7a4939d96d6e2601282ca4a07c7570e Mon Sep 17 00:00:00 2001
From: Simon Glass <sjg@chromium.org>
Date: Thu, 2 Jul 2020 21:12:13 -0600
Subject: [PATCH] console: Add a way to output to serial only

In the video drivers it is useful to print errors while debugging but
doing so risks an infinite loop as the debugging info itself may go
through the video drivers.

Add a new console function that prints information only to the serial
device, thus making it safe for use in debugging.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
---
 common/console.c  | 28 ++++++++++++++++++++++------
 include/console.h | 13 +++++++++++++
 2 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/common/console.c b/common/console.c
index 7b9816979a..07c483f820 100644
--- a/common/console.c
+++ b/common/console.c
@@ -229,18 +229,34 @@ static void console_putc(int file, const char c)
 	}
 }
 
-static void console_puts_noserial(int file, const char *s)
+/**
+ * console_puts_select() - Output a string to all console devices
+ *
+ * @file: File number to output to (e,g, stdout, see stdio.h)
+ * @serial_only: true to output only to serial, false to output to everything
+ *	else
+ * @s: String to output
+ */
+static void console_puts_select(int file, bool serial_only, const char *s)
 {
 	int i;
 	struct stdio_dev *dev;
 
 	for (i = 0; i < cd_count[file]; i++) {
+		bool is_serial;
+
 		dev = console_devices[file][i];
-		if (dev->puts != NULL && !console_dev_is_serial(dev))
+		is_serial = console_dev_is_serial(dev);
+		if (dev->puts && serial_only == is_serial)
 			dev->puts(dev, s);
 	}
 }
 
+void console_puts_select_stderr(bool serial_only, const char *s)
+{
+	console_puts_select(stderr, serial_only, s);
+}
+
 static void console_puts(int file, const char *s)
 {
 	int i;
@@ -275,9 +291,9 @@ static inline void console_putc(int file, const char c)
 	stdio_devices[file]->putc(stdio_devices[file], c);
 }
 
-static inline void console_puts_noserial(int file, const char *s)
+void console_puts_select(int file, bool serial_only, const char *s)
 {
-	if (!console_dev_is_serial(stdio_devices[file]))
+	if (serial_only == console_dev_is_serial(stdio_devices[file]))
 		stdio_devices[file]->puts(stdio_devices[file], s);
 }
 
@@ -489,7 +505,7 @@ static void print_pre_console_buffer(int flushpoint)
 		puts(buf_out);
 		break;
 	case PRE_CONSOLE_FLUSHPOINT2_EVERYTHING_BUT_SERIAL:
-		console_puts_noserial(stdout, buf_out);
+		console_puts_select(stdout, false, buf_out);
 		break;
 	}
 }
@@ -776,7 +792,7 @@ int console_announce_r(void)
 
 	display_options_get_banner(false, buf, sizeof(buf));
 
-	console_puts_noserial(stdout, buf);
+	console_puts_select(stdout, false, buf);
 #endif
 
 	return 0;
diff --git a/include/console.h b/include/console.h
index 74afe22b7e..4c6b8f2614 100644
--- a/include/console.h
+++ b/include/console.h
@@ -7,6 +7,8 @@
 #ifndef __CONSOLE_H
 #define __CONSOLE_H
 
+#include <stdbool.h>
+
 extern char console_buffer[];
 
 /* common/console.c */
@@ -72,6 +74,17 @@ int console_record_avail(void);
  */
 int console_announce_r(void);
 
+/**
+ * console_puts_select_stderr() - Output a string to selected console devices
+ *
+ * This writes to stderr only. It is useful for outputting errors
+ *
+ * @serial_only: true to output only to serial, false to output to everything
+ *	else
+ * @s: String to output
+ */
+void console_puts_select_stderr(bool serial_only, const char *s);
+
 /*
  * CONSOLE multiplexing.
  */
-- 
2.39.5