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Simon Glass2f964aa2015-01-26 18:27:07 -07001/*
2 * Early debug UART support
3 *
4 * (C) Copyright 2014 Google, Inc
5 * Writte by Simon Glass <sjg@chromium.org>
6 *
7 * SPDX-License-Identifier: GPL-2.0+
8 */
9
10#ifndef _DEBUG_UART_H
11#define _DEBUG_UART_H
12
Simon Glass2f964aa2015-01-26 18:27:07 -070013/*
14 * The debug UART is intended for use very early in U-Boot to debug problems
15 * when an ICE or other debug mechanism is not available.
16 *
17 * To use it you should:
18 * - Make sure your UART supports this interface
19 * - Enable CONFIG_DEBUG_UART
20 * - Enable the CONFIG for your UART to tell it to provide this interface
21 * (e.g. CONFIG_DEBUG_UART_NS16550)
22 * - Define the required settings as needed (see below)
23 * - Call debug_uart_init() before use
24 * - Call printch() to output a character
25 *
26 * Depending on your platform it may be possible to use this UART before a
27 * stack is available.
28 *
29 * If your UART does not support this interface you can probably add support
30 * quite easily. Remember that you cannot use driver model and it is preferred
31 * to use no stack.
32 *
33 * You must not use this UART once driver model is working and the serial
34 * drivers are up and running (done in serial_init()). Otherwise the drivers
35 * may conflict and you will get strange output.
36 *
37 *
38 * To enable the debug UART in your serial driver:
39 *
40 * - #include <debug_uart.h>
41 * - Define debug_uart_init(), trying to avoid using the stack
42 * - Define _debug_uart_putc() as static inline (avoiding stack usage)
43 * - Immediately afterwards, add DEBUG_UART_FUNCS to define the rest of the
44 * functionality (printch(), etc.)
45 */
46
47/**
48 * debug_uart_init() - Set up the debug UART ready for use
49 *
50 * This sets up the UART with the correct baud rate, etc.
51 *
52 * Available CONFIG is:
53 *
54 * - CONFIG_DEBUG_UART_BASE: Base address of UART
55 * - CONFIG_BAUDRATE: Requested baud rate
56 * - CONFIG_DEBUG_UART_CLOCK: Input clock for UART
57 */
58void debug_uart_init(void);
59
60/**
61 * printch() - Output a character to the debug UART
62 *
63 * @ch: Character to output
64 */
Simon Glassd0d73612015-06-23 15:38:32 -060065void printch(int ch);
Simon Glass2f964aa2015-01-26 18:27:07 -070066
67/**
68 * printascii() - Output an ASCII string to the debug UART
69 *
70 * @str: String to output
71 */
Simon Glassd0d73612015-06-23 15:38:32 -060072void printascii(const char *str);
Simon Glass2f964aa2015-01-26 18:27:07 -070073
74/**
75 * printhex2() - Output a 2-digit hex value
76 *
77 * @value: Value to output
78 */
Simon Glassd0d73612015-06-23 15:38:32 -060079void printhex2(uint value);
Simon Glass2f964aa2015-01-26 18:27:07 -070080
81/**
82 * printhex4() - Output a 4-digit hex value
83 *
84 * @value: Value to output
85 */
Simon Glassd0d73612015-06-23 15:38:32 -060086void printhex4(uint value);
Simon Glass2f964aa2015-01-26 18:27:07 -070087
88/**
89 * printhex8() - Output a 8-digit hex value
90 *
91 * @value: Value to output
92 */
Simon Glassd0d73612015-06-23 15:38:32 -060093void printhex8(uint value);
Simon Glass2f964aa2015-01-26 18:27:07 -070094
95/*
96 * Now define some functions - this should be inserted into the serial driver
97 */
98#define DEBUG_UART_FUNCS \
Simon Glassd0d73612015-06-23 15:38:32 -060099 void printch(int ch) \
Simon Glass2f964aa2015-01-26 18:27:07 -0700100 { \
101 _debug_uart_putc(ch); \
102 } \
103\
Simon Glassd0d73612015-06-23 15:38:32 -0600104 void printascii(const char *str) \
Simon Glass2f964aa2015-01-26 18:27:07 -0700105 { \
106 while (*str) \
107 _debug_uart_putc(*str++); \
108 } \
109\
110 static inline void printhex1(uint digit) \
111 { \
112 digit &= 0xf; \
113 _debug_uart_putc(digit > 9 ? digit - 10 + 'a' : digit + '0'); \
114 } \
115\
116 static inline void printhex(uint value, int digits) \
117 { \
118 while (digits-- > 0) \
119 printhex1(value >> (4 * digits)); \
120 } \
121\
Simon Glassd0d73612015-06-23 15:38:32 -0600122 void printhex2(uint value) \
Simon Glass2f964aa2015-01-26 18:27:07 -0700123 { \
124 printhex(value, 2); \
125 } \
126\
Simon Glassd0d73612015-06-23 15:38:32 -0600127 void printhex4(uint value) \
Simon Glass2f964aa2015-01-26 18:27:07 -0700128 { \
129 printhex(value, 4); \
130 } \
131\
Simon Glassd0d73612015-06-23 15:38:32 -0600132 void printhex8(uint value) \
Simon Glass2f964aa2015-01-26 18:27:07 -0700133 { \
134 printhex(value, 8); \
135 }
136
137#endif