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 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