1 files changed, 38 insertions, 0 deletions
diff --git a/arch/mips/loongson2ef/common/early_printk.c b/arch/mips/loongson2ef/common/early_printk.c
new file mode 100644
index 000000000000..5e2a151aa30c
--- /dev/null
+++ b/arch/mips/loongson2ef/common/early_printk.c
@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*  early printk support
+ *
+ *  Copyright (c) 2009 Philippe Vachon <philippe@cowpig.ca>
+ *  Copyright (c) 2009 Lemote Inc.
+ *  Author: Wu Zhangjin, wuzhangjin@gmail.com
+ */
+#include <linux/serial_reg.h>
+#include <asm/setup.h>
+
+#include <loongson.h>
+
+#define PORT(base, offset) (u8 *)(base + offset)
+
+static inline unsigned int serial_in(unsigned char *base, int offset)
+{
+	return readb(PORT(base, offset));
+}
+
+static inline void serial_out(unsigned char *base, int offset, int value)
+{
+	writeb(value, PORT(base, offset));
+}
+
+void prom_putchar(char c)
+{
+	int timeout;
+	unsigned char *uart_base;
+
+	uart_base = (unsigned char *)_loongson_uart_base[0];
+	timeout = 1024;
+
+	while (((serial_in(uart_base, UART_LSR) & UART_LSR_THRE) == 0) &&
+			(timeout-- > 0))
+		;
+
+	serial_out(uart_base, UART_TX, c);
+}