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 */
62 void debug_uart_init(void);
63
64 #ifdef CONFIG_DEBUG_UART_BOARD_INIT
65 void board_debug_uart_init(void);
66 #else
board_debug_uart_init(void)67 static 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 */
77 void printch(int ch);
78
79 /**
80 * printascii() - Output an ASCII string to the debug UART
81 *
82 * @str: String to output
83 */
84 void printascii(const char *str);
85
86 /**
87 * printhex2() - Output a 2-digit hex value
88 *
89 * @value: Value to output
90 */
91 void printhex2(uint value);
92
93 /**
94 * printhex4() - Output a 4-digit hex value
95 *
96 * @value: Value to output
97 */
98 void printhex4(uint value);
99
100 /**
101 * printhex8() - Output a 8-digit hex value
102 *
103 * @value: Value to output
104 */
105 void printhex8(uint value);
106
107 #ifdef CONFIG_DEBUG_UART_ANNOUNCE
108 #define _DEBUG_UART_ANNOUNCE printascii("<debug_uart> ");
109 #else
110 #define _DEBUG_UART_ANNOUNCE
111 #endif
112
113 #define serial_dout(reg, value) \
114 serial_out_shift((char *)com_port + \
115 ((char *)reg - (char *)com_port) * \
116 (1 << CONFIG_DEBUG_UART_SHIFT), \
117 CONFIG_DEBUG_UART_SHIFT, value)
118 #define serial_din(reg) \
119 serial_in_shift((char *)com_port + \
120 ((char *)reg - (char *)com_port) * \
121 (1 << CONFIG_DEBUG_UART_SHIFT), \
122 CONFIG_DEBUG_UART_SHIFT)
123
124 /*
125 * Now define some functions - this should be inserted into the serial driver
126 */
127 #define DEBUG_UART_FUNCS \
128 \
129 static inline void _printch(int ch) \
130 { \
131 if (ch == '\n') \
132 _debug_uart_putc('\r'); \
133 _debug_uart_putc(ch); \
134 } \
135 \
136 void printch(int ch) \
137 { \
138 _printch(ch); \
139 } \
140 \
141 void printascii(const char *str) \
142 { \
143 while (*str) \
144 _printch(*str++); \
145 } \
146 \
147 static inline void printhex1(uint digit) \
148 { \
149 digit &= 0xf; \
150 _debug_uart_putc(digit > 9 ? digit - 10 + 'a' : digit + '0'); \
151 } \
152 \
153 static inline void printhex(uint value, int digits) \
154 { \
155 while (digits-- > 0) \
156 printhex1(value >> (4 * digits)); \
157 } \
158 \
159 void printhex2(uint value) \
160 { \
161 printhex(value, 2); \
162 } \
163 \
164 void printhex4(uint value) \
165 { \
166 printhex(value, 4); \
167 } \
168 \
169 void printhex8(uint value) \
170 { \
171 printhex(value, 8); \
172 } \
173 \
174 void debug_uart_init(void) \
175 { \
176 board_debug_uart_init(); \
177 _debug_uart_init(); \
178 _DEBUG_UART_ANNOUNCE \
179 } \
180
181 #endif
182