From 7ebe17ed614991a6a11bf3d4523334308a545f52 Mon Sep 17 00:00:00 2001
From: jmcneill <jmcneill@FreeBSD.org>
Date: Mon, 29 Aug 2016 20:01:53 +0000
Subject: [PATCH] When the EFI implementation (like U-Boot) does not support
 WaitForKey, we can emulate efi_cons_poll(0 with a flag and caching the last
 key read with ReadKeyStroke. This fixes the loader.efi countdown timer on
 Pine64 (and other U-Boot + EFI using platforms).

Reviewed by:		imp, manu
Differential Revision:	https://reviews.freebsd.org/D7670
---
 sys/boot/efi/libefi/efi_console.c | 36 ++++++++++++++++++++++++-------
 1 file changed, 28 insertions(+), 8 deletions(-)

diff --git a/sys/boot/efi/libefi/efi_console.c b/sys/boot/efi/libefi/efi_console.c
index 6ad5d3c1e142..450ed46a23f5 100644
--- a/sys/boot/efi/libefi/efi_console.c
+++ b/sys/boot/efi/libefi/efi_console.c
@@ -51,6 +51,9 @@ void HO(void);
 void end_term(void);
 #endif
 
+static EFI_INPUT_KEY key_cur;
+static int key_pending;
+
 static void efi_cons_probe(struct console *);
 static int efi_cons_init(int);
 void efi_cons_putchar(int);
@@ -436,14 +439,20 @@ efi_cons_getchar()
 	EFI_STATUS status;
 	UINTN junk;
 
-	/* Try to read a key stroke. We wait for one if none is pending. */
-	status = conin->ReadKeyStroke(conin, &key);
-	while (status == EFI_NOT_READY) {
-		/* Some EFI implementation (u-boot for example) do not support WaitForKey */
-		if (conin->WaitForKey != NULL)
-			BS->WaitForEvent(1, &conin->WaitForKey, &junk);
+	if (key_pending) {
+		key = key_cur;
+		key_pending = 0;
+	} else {
+		/* Try to read a key stroke. We wait for one if none is pending. */
 		status = conin->ReadKeyStroke(conin, &key);
+		while (status == EFI_NOT_READY) {
+			/* Some EFI implementation (u-boot for example) do not support WaitForKey */
+			if (conin->WaitForKey != NULL)
+				BS->WaitForEvent(1, &conin->WaitForKey, &junk);
+			status = conin->ReadKeyStroke(conin, &key);
+		}
 	}
+
 	switch (key.ScanCode) {
 	case 0x17: /* ESC */
 		return (0x1b);  /* esc */
@@ -456,9 +465,20 @@ efi_cons_getchar()
 int
 efi_cons_poll()
 {
+	EFI_INPUT_KEY key;
+	EFI_STATUS status;
+
+	if (conin->WaitForKey == NULL) {
+		if (key_pending)
+			return (1);
+		status = conin->ReadKeyStroke(conin, &key);
+		if (status == EFI_SUCCESS) {
+			key_cur = key;
+			key_pending = 1;
+		}
+		return (key_pending);
+	}
 
-	if (conin->WaitForKey == NULL)
-		return (1);
 	/* This can clear the signaled state. */
 	return (BS->CheckEvent(conin->WaitForKey) == EFI_SUCCESS);
 }