1/* SPDX-License-Identifier: GPL-2.0+ */
2/*
3 * Early debug UART support
4 *
5 * (C) Copyright 2014 Google, Inc
6 * Writte by Simon Glass <sjg@chromium.org>
7 */
8
9#ifndef _DEBUG_UART_H
10#define _DEBUG_UART_H
11
12/*
13 * The debug UART is intended for use very early in U-Boot to debug problems
14 * when an ICE or other debug mechanism is not available.
15 *
16 * To use it you should:
17 * - Make sure your UART supports this interface
18 * - Enable CONFIG_DEBUG_UART
19 * - Enable the CONFIG for your UART to tell it to provide this interface
20 *       (e.g. CONFIG_DEBUG_UART_NS16550)
21 * - Define the required settings as needed (see below)
22 * - Call debug_uart_init() before use
23 * - Call printch() to output a character
24 *
25 * Depending on your platform it may be possible to use this UART before a
26 * stack is available.
27 *
28 * If your UART does not support this interface you can probably add support
29 * quite easily. Remember that you cannot use driver model and it is preferred
30 * to use no stack.
31 *
32 * You must not use this UART once driver model is working and the serial
33 * drivers are up and running (done in serial_init()). Otherwise the drivers
34 * may conflict and you will get strange output.
35 *
36 *
37 * To enable the debug UART in your serial driver:
38 *
39 * - #include <debug_uart.h>
40 * - Define _debug_uart_init(), trying to avoid using the stack
41 * - Define _debug_uart_putc() as static inline (avoiding stack usage)
42 * - Immediately afterwards, add DEBUG_UART_FUNCS to define the rest of the
43 *     functionality (printch(), etc.)
44 *
45 * If your board needs additional init for the UART to work, enable
46 * CONFIG_DEBUG_UART_BOARD_INIT and write a function called
47 * board_debug_uart_init() to perform that init. When debug_uart_init() is
48 * called, the init will happen automatically.
49 */
50
51/**
52 * debug_uart_init() - Set up the debug UART ready for use
53 *
54 * This sets up the UART with the correct baud rate, etc.
55 *
56 * Available CONFIG is:
57 *
58 *    - CONFIG_DEBUG_UART_BASE: Base address of UART
59 *    - CONFIG_BAUDRATE: Requested baud rate
60 *    - CONFIG_DEBUG_UART_CLOCK: Input clock for UART
61 */
62void debug_uart_init(void);
63
64#ifdef CONFIG_DEBUG_UART_BOARD_INIT
65void board_debug_uart_init(void);
66#else
67static inline void board_debug_uart_init(void)
68{
69}
70#endif
71
72/**
73 * printch() - Output a character to the debug UART
74 *
75 * @ch:		Character to output
76 */
77void printch(int ch);
78
79/**
80 * printascii() - Output an ASCII string to the debug UART
81 *
82 * @str:	String to output
83 */
84void printascii(const char *str);
85
86/**
87 * printhex2() - Output a 2-digit hex value
88 *
89 * @value:	Value to output
90 */
91void printhex2(unsigned int value);
92
93/**
94 * printhex4() - Output a 4-digit hex value
95 *
96 * @value:	Value to output
97 */
98void printhex4(unsigned int value);
99
100/**
101 * printhex8() - Output a 8-digit hex value
102 *
103 * @value:	Value to output
104 */
105void printhex8(unsigned int value);
106
107/**
108 * printdec() - Output a decimalism value
109 *
110 * @value:	Value to output
111 */
112void printdec(unsigned int value);
113
114#ifdef CONFIG_DEBUG_UART_ANNOUNCE
115#define _DEBUG_UART_ANNOUNCE	printascii("\n<debug_uart>\n");
116#else
117#define _DEBUG_UART_ANNOUNCE
118#endif
119
120#define serial_dout(reg, value)	\
121	serial_out_shift((char *)com_port + \
122		((char *)reg - (char *)com_port) * \
123			(1 << CONFIG_DEBUG_UART_SHIFT), \
124		CONFIG_DEBUG_UART_SHIFT, value)
125#define serial_din(reg) \
126	serial_in_shift((char *)com_port + \
127		((char *)reg - (char *)com_port) * \
128			(1 << CONFIG_DEBUG_UART_SHIFT), \
129		CONFIG_DEBUG_UART_SHIFT)
130
131/*
132 * Now define some functions - this should be inserted into the serial driver
133 */
134#define DEBUG_UART_FUNCS \
135\
136	static inline void _printch(int ch) \
137	{ \
138		if (ch == '\n') \
139			_debug_uart_putc('\r'); \
140		_debug_uart_putc(ch); \
141	} \
142\
143	void printch(int ch) \
144	{ \
145		_printch(ch); \
146	} \
147\
148	void printascii(const char *str) \
149	{ \
150		while (*str) \
151			_printch(*str++); \
152	} \
153\
154	static inline void printhex1(unsigned int digit) \
155	{ \
156		digit &= 0xf; \
157		_debug_uart_putc(digit > 9 ? digit - 10 + 'a' : digit + '0'); \
158	} \
159\
160	static inline void printhex(unsigned int value, int digits) \
161	{ \
162		while (digits-- > 0) \
163			printhex1(value >> (4 * digits)); \
164	} \
165\
166	void printhex2(unsigned int value) \
167	{ \
168		printhex(value, 2); \
169	} \
170\
171	void printhex4(unsigned int value) \
172	{ \
173		printhex(value, 4); \
174	} \
175\
176	void printhex8(unsigned int value) \
177	{ \
178		printhex(value, 8); \
179	} \
180\
181	void printdec(unsigned int value) \
182	{ \
183		if (value > 10) { \
184			printdec(value / 10); \
185			value %= 10; \
186		} else if (value == 10) { \
187			_debug_uart_putc('1'); \
188			value = 0; \
189		} \
190		_debug_uart_putc('0' + value); \
191	} \
192\
193	void debug_uart_init(void) \
194	{ \
195		board_debug_uart_init(); \
196		_debug_uart_init(); \
197		_DEBUG_UART_ANNOUNCE \
198	} \
199
200#endif
201