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(unsigned int value);
92
93 /**
94 * printhex4() - Output a 4-digit hex value
95 *
96 * @value: Value to output
97 */
98 void printhex4(unsigned int value);
99
100 /**
101 * printhex8() - Output a 8-digit hex value
102 *
103 * @value: Value to output
104 */
105 void printhex8(unsigned int value);
106
107 /**
108 * printdec() - Output a decimalism value
109 *
110 * @value: Value to output
111 */
112 void 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