1 files changed, 52 insertions, 0 deletions
diff --git a/arch/mips/boot/compressed/uart-16550.c b/arch/mips/boot/compressed/uart-16550.c
new file mode 100644
index 0000000000..96d28f2111
--- /dev/null
+++ b/arch/mips/boot/compressed/uart-16550.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 16550 compatible uart based serial debug support for zboot
+ */
+
+#include <linux/types.h>
+#include <linux/serial_reg.h>
+
+#include <asm/addrspace.h>
+
+#if defined(CONFIG_MACH_LOONGSON64) || defined(CONFIG_MIPS_MALTA)
+#define UART_BASE 0x1fd003f8
+#define PORT(offset) (CKSEG1ADDR(UART_BASE) + (offset))
+#endif
+
+#ifdef CONFIG_AR7
+#include <ar7.h>
+#define PORT(offset) (CKSEG1ADDR(AR7_REGS_UART0) + (4 * offset))
+#endif
+
+#ifdef CONFIG_MACH_INGENIC
+#define INGENIC_UART_BASE_ADDR	(0x10030000 + 0x1000 * CONFIG_ZBOOT_INGENIC_UART)
+#define PORT(offset) (CKSEG1ADDR(INGENIC_UART_BASE_ADDR) + (4 * offset))
+#endif
+
+#ifndef IOTYPE
+#define IOTYPE char
+#endif
+
+#ifndef PORT
+#error please define the serial port address for your own machine
+#endif
+
+static inline unsigned int serial_in(int offset)
+{
+	return *((volatile IOTYPE *)PORT(offset)) & 0xFF;
+}
+
+static inline void serial_out(int offset, int value)
+{
+	*((volatile IOTYPE *)PORT(offset)) = value & 0xFF;
+}
+
+void putc(char c)
+{
+	int timeout = 1000000;
+
+	while (((serial_in(UART_LSR) & UART_LSR_THRE) == 0) && (timeout-- > 0))
+		;
+
+	serial_out(UART_TX, c);
+}