1 /* 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 13 /* 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 * If your board needs additional init for the UART to work, enable 47 * CONFIG_DEBUG_UART_BOARD_INIT and write a function called 48 * board_debug_uart_init() to perform that init. When debug_uart_init() is 49 * called, the init will happen automatically. 50 */ 51 52 /** 53 * debug_uart_init() - Set up the debug UART ready for use 54 * 55 * This sets up the UART with the correct baud rate, etc. 56 * 57 * Available CONFIG is: 58 * 59 * - CONFIG_DEBUG_UART_BASE: Base address of UART 60 * - CONFIG_BAUDRATE: Requested baud rate 61 * - CONFIG_DEBUG_UART_CLOCK: Input clock for UART 62 */ 63 void debug_uart_init(void); 64 65 #ifdef CONFIG_DEBUG_UART_BOARD_INIT 66 void board_debug_uart_init(void); 67 #else 68 static inline void board_debug_uart_init(void) 69 { 70 } 71 #endif 72 73 /** 74 * printch() - Output a character to the debug UART 75 * 76 * @ch: Character to output 77 */ 78 void printch(int ch); 79 int debug_uart_getc(void); 80 int debug_uart_tstc(void); 81 int debug_uart_clrc(void); 82 int debug_uart_setbrg(void); 83 84 /** 85 * printascii() - Output an ASCII string to the debug UART 86 * 87 * @str: String to output 88 */ 89 void printascii(const char *str); 90 91 /** 92 * printhex2() - Output a 2-digit hex value 93 * 94 * @value: Value to output 95 */ 96 void printhex2(uint value); 97 98 /** 99 * printhex4() - Output a 4-digit hex value 100 * 101 * @value: Value to output 102 */ 103 void printhex4(uint value); 104 105 /** 106 * printhex8() - Output a 8-digit hex value 107 * 108 * @value: Value to output 109 */ 110 void printhex8(uint value); 111 112 /** 113 * printdec() - Output a decimalism value 114 * 115 * @value: Value to output 116 */ 117 void printdec(uint value); 118 119 #ifdef CONFIG_DEBUG_UART_ANNOUNCE 120 #define _DEBUG_UART_ANNOUNCE printascii("<debug_uart> "); 121 #else 122 #define _DEBUG_UART_ANNOUNCE 123 #endif 124 125 #define serial_dout(reg, value) \ 126 serial_out_shift((char *)com_port + \ 127 ((char *)reg - (char *)com_port) * \ 128 (1 << CONFIG_DEBUG_UART_SHIFT), \ 129 CONFIG_DEBUG_UART_SHIFT, value) 130 #define serial_din(reg) \ 131 serial_in_shift((char *)com_port + \ 132 ((char *)reg - (char *)com_port) * \ 133 (1 << CONFIG_DEBUG_UART_SHIFT), \ 134 CONFIG_DEBUG_UART_SHIFT) 135 136 /* 137 * Now define some functions - this should be inserted into the serial driver 138 */ 139 #define DEBUG_UART_FUNCS \ 140 \ 141 static inline void _printch(int ch) \ 142 { \ 143 if (ch == '\n') \ 144 _debug_uart_putc('\r'); \ 145 _debug_uart_putc(ch); \ 146 } \ 147 \ 148 void printch(int ch) \ 149 { \ 150 _printch(ch); \ 151 } \ 152 \ 153 int debug_uart_getc(void)\ 154 { \ 155 return _debug_uart_getc(); \ 156 } \ 157 \ 158 int debug_uart_tstc(void)\ 159 { \ 160 return _debug_uart_tstc(true); \ 161 } \ 162 \ 163 int debug_uart_clrc(void)\ 164 { \ 165 return _debug_uart_clrc(); \ 166 } \ 167 \ 168 int debug_uart_setbrg(void)\ 169 { \ 170 return _debug_uart_setbrg(); \ 171 } \ 172 \ 173 void printascii(const char *str) \ 174 { \ 175 while (*str) \ 176 _printch(*str++); \ 177 } \ 178 \ 179 static inline void printhex1(uint digit) \ 180 { \ 181 digit &= 0xf; \ 182 _debug_uart_putc(digit > 9 ? digit - 10 + 'a' : digit + '0'); \ 183 } \ 184 \ 185 static inline void printhex(uint value, int digits) \ 186 { \ 187 while (digits-- > 0) \ 188 printhex1(value >> (4 * digits)); \ 189 } \ 190 \ 191 void printhex2(uint value) \ 192 { \ 193 printhex(value, 2); \ 194 } \ 195 \ 196 void printhex4(uint value) \ 197 { \ 198 printhex(value, 4); \ 199 } \ 200 \ 201 void printhex8(uint value) \ 202 { \ 203 printhex(value, 8); \ 204 } \ 205 \ 206 void printdec(uint value) \ 207 { \ 208 if (value > 10) { \ 209 printdec(value / 10); \ 210 value %= 10; \ 211 } else if (value == 10) { \ 212 _debug_uart_putc('1'); \ 213 value = 0; \ 214 } \ 215 _debug_uart_putc('0' + value); \ 216 } \ 217 \ 218 void debug_uart_init(void) \ 219 { \ 220 board_debug_uart_init(); \ 221 _debug_uart_init(); \ 222 _DEBUG_UART_ANNOUNCE \ 223 } \ 224 225 #endif 226