voron

commit 633f6a73abb4d28ed14bd182e267d1866d99d515
parent 0d4188028ef7ba4662e033a674b23d9ffce84637
Author: oblique <psyberbits@gmail.com>
Date:   Wed,  9 Jan 2013 06:03:11 +0200

rs232.c: check if TX FIFO is full before waiting to get empty.

Diffstat:
M
include/uart.h
 | 
1
+
M
kernel/rs232.c
 | 
13
+++++++++----

2 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/include/uart.h b/include/uart.h
@@ -4,6 +4,7 @@
 #include <inttypes.h>
 
 /* TRM p.4459 */
+#define TX_FIFO_FULL	(1<<0)
 #define TX_FIFO_E	(1<<5)
 #define RX_FIFO_E	(1<<0)
 #define RHR_IT		(1<<0)
diff --git a/kernel/rs232.c b/kernel/rs232.c
@@ -24,13 +24,18 @@ int
 rs232_putchar(int c)
 {
 	if (c == '\n') {
+		if (readl(&uart->ssr) & TX_FIFO_FULL) {
+			while ((readl(&uart->lsr) & TX_FIFO_E) == 0)
+				;
+		}
+		writel('\r', &uart->thr);
+	}
+	/* if UART TX FIFO is full */
+	if (readl(&uart->ssr) & TX_FIFO_FULL) {
+		/* while UART TX FIFO is not empty */
 		while ((readl(&uart->lsr) & TX_FIFO_E) == 0)
 			;
-		writel('\r', &uart->thr);
 	}
-	/* while UART TX FIFO is not empty */
-	while ((readl(&uart->lsr) & TX_FIFO_E) == 0)
-		;
 	/* write the character */
 	writel(c, &uart->thr);
 	return c;