console: add console_flush_stdin()

Add a common helper console_flush_stdin() to drain all pending
characters from stdin. This consolidates the open-coded
while (tstc()) getchar() pattern that appeared in multiple places
across the tree.

Signed-off-by: Gregor Herburger <gregor.herburger@linutronix.de>
Reviewed-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>
Reviewed-by: Simon Glass <sjg@chromium.org>

cmd/conitrace.c

@@ -6,6 +6,7 @@
  * Copyright (c) 2018, Heinrich Schuchardt <xypron.glpk@gmx.de>
  */
 #include <command.h>
+#include <console.h>
 #include <linux/delay.h>
 
 static int do_conitrace(struct cmd_tbl *cmdtp, int flag, int argc,
@@ -17,8 +18,7 @@ static int do_conitrace(struct cmd_tbl *cmdtp, int flag, int argc,
 	printf("To terminate type 'x'\n");
 
 	/* Empty input buffer */
-	while (tstc())
-		getchar();
+	console_flush_stdin();
 
 	for (;;) {
 		int c = getchar();

cmd/eficonfig.c

@@ -6,8 +6,9 @@
  */
 
 #include <ansi.h>
-#include <cli.h>
 #include <charset.h>
+#include <cli.h>
+#include <console.h>
 #include <efi_device_path.h>
 #include <efi_loader.h>
 #include <efi_load_initrd.h>
@@ -167,8 +168,7 @@ static void eficonfig_menu_adjust(struct efimenu *efi_menu, bool add)
 void eficonfig_print_msg(char *msg)
 {
 	/* Flush input */
-	while (tstc())
-		getchar();
+	console_flush_stdin();
 
 	printf(ANSI_CURSOR_HIDE
 	       ANSI_CLEAR_CONSOLE

cmd/eficonfig_sbkey.c

@@ -7,6 +7,7 @@
 
 #include <ansi.h>
 #include <charset.h>
+#include <console.h>
 #include <hexdump.h>
 #include <log.h>
 #include <malloc.h>
@@ -288,8 +289,7 @@ static efi_status_t eficonfig_process_show_siglist(void *data)
 		}
 	}
 
-	while (tstc())
-		getchar();
+	console_flush_stdin();
 
 	printf("\n\n  Press any key to continue");
 	getchar();

common/autoboot.c

@@ -315,15 +315,6 @@ static int passwd_abort_key(uint64_t etime)
 	return abort;
 }
 
-/**
- * flush_stdin() - drops all pending characters from stdin
- */
-static void flush_stdin(void)
-{
-	while (tstc())
-		(void)getchar();
-}
-
 /**
  * fallback_to_sha256() - check whether we should fall back to sha256
  *                        password checking
@@ -354,7 +345,7 @@ static int abortboot_key_sequence(int bootdelay)
 	uint64_t etime = endtick(bootdelay);
 
 	if (IS_ENABLED(CONFIG_AUTOBOOT_FLUSH_STDIN))
-		flush_stdin();
+		console_flush_stdin();
 #  ifdef CONFIG_AUTOBOOT_PROMPT
 	/*
 	 * CONFIG_AUTOBOOT_PROMPT includes the %d for all boards.

common/console.c

@@ -643,6 +643,15 @@ int tstc(void)
 	return serial_tstc();
 }
 
+/**
+ * console_flush_stdin() - drops all pending characters from stdin
+ */
+void console_flush_stdin(void)
+{
+	while (tstc())
+		(void)getchar();
+}
+
 #define PRE_CONSOLE_FLUSHPOINT1_SERIAL			0
 #define PRE_CONSOLE_FLUSHPOINT2_EVERYTHING_BUT_SERIAL	1
 
@@ -914,8 +923,7 @@ int confirm_yesno(void)
 	char str_input[5];
 
 	/* Flush input */
-	while (tstc())
-		getchar();
+	console_flush_stdin();
 	i = 0;
 	while (i < sizeof(str_input)) {
 		str_input[i] = getchar();

include/console.h

@@ -202,6 +202,11 @@ int console_clear(void);
  */
 int console_remove_by_name(const char *name);
 
+/**
+ * console_flush_stdin() - drops all pending characters from stdin
+ */
+void console_flush_stdin(void);
+
 /*
  * CONSOLE multiplexing.
  */

lib/efi_loader/efi_console.c

@@ -9,6 +9,7 @@
 
 #include <ansi.h>
 #include <charset.h>
+#include <console.h>
 #include <efi_device_path.h>
 #include <malloc.h>
 #include <time.h>
@@ -299,8 +300,7 @@ static int query_console_serial(int *rows, int *cols)
 	int n[2];
 
 	/* Empty input buffer */
-	while (tstc())
-		getchar();
+	console_flush_stdin();
 
 	/*
 	 * Not all terminals understand CSI [18t for querying the console size.
@@ -960,8 +960,7 @@ static void efi_cin_check(void)
  */
 static void efi_cin_empty_buffer(void)
 {
-	while (tstc())
-		getchar();
+	console_flush_stdin();
 	key_available = false;
 }