[PATCH] lib: utils/serial: Modify uart_getc to a blocking function

[Xiang W]

If uart_getc is non-blocking, if the sending end is faster than the
receiving end, the data received by some functions(sbi_gets) is
incomplete

Signed-off-by: Xiang W <wxjstz at 126.com>
---
 lib/utils/serial/gaisler-uart.c |  5 ++---
 lib/utils/serial/shakti-uart.c  |  7 +++----
 lib/utils/serial/sifive-uart.c  |  9 +++++----
 lib/utils/serial/uart8250.c     |  6 +++---
 lib/utils/sys/htif.c            | 11 +++++------
 5 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/lib/utils/serial/gaisler-uart.c b/lib/utils/serial/gaisler-uart.c
index 49298e9..1dc5ae0 100644
--- a/lib/utils/serial/gaisler-uart.c
+++ b/lib/utils/serial/gaisler-uart.c
@@ -51,9 +51,8 @@ static void gaisler_uart_putc(char ch)
 
 static int gaisler_uart_getc(void)
 {
-	u32 ret = get_reg(UART_REG_STATUS);
-	if (!(ret & UART_STATUS_DATAREADY))
-		return -1;
+	while (!(get_reg(UART_REG_STATUS) & UART_STATUS_DATAREADY))
+		;
 	return get_reg(UART_REG_DATA) & UART_DATA_DATA;
 }
 
diff --git a/lib/utils/serial/shakti-uart.c b/lib/utils/serial/shakti-uart.c
index e77a985..a5b72aa 100644
--- a/lib/utils/serial/shakti-uart.c
+++ b/lib/utils/serial/shakti-uart.c
@@ -32,10 +32,9 @@ static void shakti_uart_putc(char ch)
 
 static int shakti_uart_getc(void)
 {
-	u16 status = readw(uart_base + REG_STATUS);
-	if (status & UART_RX_FULL)
-		return readb(uart_base + REG_RX);
-	return -1;
+	while (!(readw(uart_base + REG_STATUS) & UART_RX_FULL))
+		;
+	return readb(uart_base + REG_RX);
 }
 
 static struct sbi_console_device shakti_console = {
diff --git a/lib/utils/serial/sifive-uart.c b/lib/utils/serial/sifive-uart.c
index 57d80fa..68a9ca7 100644
--- a/lib/utils/serial/sifive-uart.c
+++ b/lib/utils/serial/sifive-uart.c
@@ -76,10 +76,11 @@ static void sifive_uart_putc(char ch)
 
 static int sifive_uart_getc(void)
 {
-	u32 ret = get_reg(UART_REG_RXFIFO);
-	if (!(ret & UART_RXFIFO_EMPTY))
-		return ret & UART_RXFIFO_DATA;
-	return -1;
+	u32 ret;
+	do
+		ret = get_reg(UART_REG_RXFIFO);
+	while (ret & UART_RXFIFO_EMPTY);
+	return ret & UART_RXFIFO_DATA;
 }
 
 static struct sbi_console_device sifive_console = {
diff --git a/lib/utils/serial/uart8250.c b/lib/utils/serial/uart8250.c
index 1cf6624..bab8111 100644
--- a/lib/utils/serial/uart8250.c
+++ b/lib/utils/serial/uart8250.c
@@ -79,9 +79,9 @@ static void uart8250_putc(char ch)
 
 static int uart8250_getc(void)
 {
-	if (get_reg(UART_LSR_OFFSET) & UART_LSR_DR)
-		return get_reg(UART_RBR_OFFSET);
-	return -1;
+	while (!(get_reg(UART_LSR_OFFSET) & UART_LSR_DR))
+		;
+	return get_reg(UART_RBR_OFFSET);
 }
 
 static struct sbi_console_device uart8250_console = {
diff --git a/lib/utils/sys/htif.c b/lib/utils/sys/htif.c
index 7c69c7f..dfda30a 100644
--- a/lib/utils/sys/htif.c
+++ b/lib/utils/sys/htif.c
@@ -47,7 +47,7 @@
 
 volatile uint64_t tohost __attribute__((section(".htif")));
 volatile uint64_t fromhost __attribute__((section(".htif")));
-static int htif_console_buf;
+static int htif_console_buf = -1;
 static spinlock_t htif_lock = SPIN_LOCK_INITIALIZER;
 
 static void __check_fromhost()
@@ -130,12 +130,11 @@ static int htif_getc(void)
 
 	spin_lock(&htif_lock);
 
-	__check_fromhost();
+	while (htif_console_buf < 0)
+		__check_fromhost();
 	ch = htif_console_buf;
-	if (ch >= 0) {
-		htif_console_buf = -1;
-		__set_tohost(HTIF_DEV_CONSOLE, HTIF_CONSOLE_CMD_GETC, 0);
-	}
+	htif_console_buf = -1;
+	__set_tohost(HTIF_DEV_CONSOLE, HTIF_CONSOLE_CMD_GETC, 0);
 
 	spin_unlock(&htif_lock);
 
-- 
2.30.2