1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * 16550 compatible uart based serial debug support for zboot
4  */
5 
6 #include <linux/types.h>
7 #include <linux/serial_reg.h>
8 
9 #include <asm/addrspace.h>
10 
11 #define UART_BASE 0x1fe001e0
12 #define PORT(offset) (TO_UNCACHE(UART_BASE) + (offset))
13 
14 #ifndef IOTYPE
15 #define IOTYPE char
16 #endif
17 
18 #ifndef PORT
19 #error please define the serial port address for your own machine
20 #endif
21 
serial_in(int offset)22 static inline unsigned int serial_in(int offset)
23 {
24 	return *((volatile IOTYPE *)PORT(offset)) & 0xFF;
25 }
26 
serial_out(int offset, int value)27 static inline void serial_out(int offset, int value)
28 {
29 	*((volatile IOTYPE *)PORT(offset)) = value & 0xFF;
30 }
31 
putc(char c)32 void putc(char c)
33 {
34 	int timeout = 1000000;
35 
36 	while (((serial_in(UART_LSR) & UART_LSR_THRE) == 0) && (timeout-- > 0))
37 		;
38 
39 	serial_out(UART_TX, c);
40 }
41