9os

commit 27a83338a8e8dbcd8271b4baba09fa85356b7c5f
parent f40c7be4d1c9a95cd0726ccceb949afd1a03b6a9
Author: Dimitris Papastamos <dimitris.papastamos@arm.com>
Date:   Tue,  6 Nov 2018 11:59:52 +0000

[uart] Add retry count

The retry count is set to an arbitrary number for now.

Change-Id: I24e34fe02a4ee66bd7f0a1f0160e15564af20a70
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>

Diffstat:
M
drivers/uart.c
 | 
26
+++++++++++++++++++-------

1 file changed, 19 insertions(+), 7 deletions(-)
diff --git a/drivers/uart.c b/drivers/uart.c
@@ -1,6 +1,8 @@
 #include <uart.h>
 #include <rcode.h>
 
+#define NRETRY	10000
+
 #define CR	0x30
 #define FBRD	0x28
 #define IBRD	0x24
@@ -36,10 +38,12 @@ static void
 flush(void)
 {
 	char *base = bss->uartbase;
+	int nretry = NRETRY;
 
-	while ((inm32(base + CR) & CR_EN) &&
-	       (inm32(base + FR) & FR_TXFE))
-		;
+	while (nretry-- > 0)
+		if (!((inm32(base + CR) & CR_EN) &&
+		      (inm32(base + FR) & FR_TXFE)))
+			break;
 }
 
 static void
@@ -67,9 +71,13 @@ int
 uartgetc(void)
 {
 	char *base = bss->uartbase;
+	int nretry = NRETRY;
 
-	while (inm32(base + FR) & FR_RXFE)
-		;
+	while (nretry-- > 0)
+		if (!(inm32(base + FR) & FR_RXFE))
+			break;
+	if (nretry == 0)
+		return -1;
 	return inm8(base + DR);
 }
 
@@ -77,9 +85,13 @@ int
 uartputc(int c)
 {
 	char *base = bss->uartbase;
+	int nretry = NRETRY;
 
-	while (inm32(base + FR) & FR_TXFF)
-		;
+	while (nretry-- > 0)
+		if (!(inm32(base + FR) & FR_TXFF))
+			break;
+	if (nretry == 0)
+		return -1;
 	outm8(c, base + DR);
 	return c;
 }