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_flushc(void); 83 int debug_uart_setbrg(void); 84 85 /** 86 * printascii() - Output an ASCII string to the debug UART 87 * 88 * @str: String to output 89 */ 90 void printascii(const char *str); 91 92 /** 93 * printhex2() - Output a 2-digit hex value 94 * 95 * @value: Value to output 96 */ 97 void printhex2(uint value); 98 99 /** 100 * printhex4() - Output a 4-digit hex value 101 * 102 * @value: Value to output 103 */ 104 void printhex4(uint value); 105 106 /** 107 * printhex8() - Output a 8-digit hex value 108 * 109 * @value: Value to output 110 */ 111 void printhex8(uint value); 112 113 /** 114 * printdec() - Output a decimalism value 115 * 116 * @value: Value to output 117 */ 118 void printdec(uint value); 119 120 #ifdef CONFIG_DEBUG_UART_ANNOUNCE 121 #define _DEBUG_UART_ANNOUNCE printascii("<debug_uart> "); 122 #else 123 #define _DEBUG_UART_ANNOUNCE 124 #endif 125 126 #define serial_dout(reg, value) \ 127 serial_out_shift((char *)com_port + \ 128 ((char *)reg - (char *)com_port) * \ 129 (1 << CONFIG_DEBUG_UART_SHIFT), \ 130 CONFIG_DEBUG_UART_SHIFT, value) 131 #define serial_din(reg) \ 132 serial_in_shift((char *)com_port + \ 133 ((char *)reg - (char *)com_port) * \ 134 (1 << CONFIG_DEBUG_UART_SHIFT), \ 135 CONFIG_DEBUG_UART_SHIFT) 136 137 /* 138 * Now define some functions - this should be inserted into the serial driver 139 */ 140 #define DEBUG_UART_FUNCS \ 141 \ 142 static inline void _printch(int ch) \ 143 { \ 144 if (ch == '\n') \ 145 _debug_uart_putc('\r'); \ 146 _debug_uart_putc(ch); \ 147 } \ 148 \ 149 void printch(int ch) \ 150 { \ 151 _printch(ch); \ 152 } \ 153 \ 154 int debug_uart_getc(void)\ 155 { \ 156 return _debug_uart_getc(); \ 157 } \ 158 \ 159 int debug_uart_tstc(void)\ 160 { \ 161 return _debug_uart_tstc(true); \ 162 } \ 163 \ 164 int debug_uart_clrc(void)\ 165 { \ 166 return _debug_uart_clrc(); \ 167 } \ 168 \ 169 int debug_uart_flushc(void)\ 170 { \ 171 return _debug_uart_flushc(); \ 172 } \ 173 \ 174 int debug_uart_setbrg(void)\ 175 { \ 176 return _debug_uart_setbrg(); \ 177 } \ 178 \ 179 void printascii(const char *str) \ 180 { \ 181 while (*str) \ 182 _printch(*str++); \ 183 } \ 184 \ 185 static inline void printhex1(uint digit) \ 186 { \ 187 digit &= 0xf; \ 188 _debug_uart_putc(digit > 9 ? digit - 10 + 'a' : digit + '0'); \ 189 } \ 190 \ 191 static inline void printhex(uint value, int digits) \ 192 { \ 193 while (digits-- > 0) \ 194 printhex1(value >> (4 * digits)); \ 195 } \ 196 \ 197 void printhex2(uint value) \ 198 { \ 199 printhex(value, 2); \ 200 } \ 201 \ 202 void printhex4(uint value) \ 203 { \ 204 printhex(value, 4); \ 205 } \ 206 \ 207 void printhex8(uint value) \ 208 { \ 209 printhex(value, 8); \ 210 } \ 211 \ 212 void printdec(uint value) \ 213 { \ 214 if (value > 10) { \ 215 printdec(value / 10); \ 216 value %= 10; \ 217 } else if (value == 10) { \ 218 _debug_uart_putc('1'); \ 219 value = 0; \ 220 } \ 221 _debug_uart_putc('0' + value); \ 222 } \ 223 \ 224 void debug_uart_init(void) \ 225 { \ 226 board_debug_uart_init(); \ 227 _debug_uart_init(); \ 228 _DEBUG_UART_ANNOUNCE \ 229 } \ 230 231 #endif 232