1 /* -*- linux-c -*- ------------------------------------------------------- * 2 * 3 * Copyright (C) 1991, 1992 Linus Torvalds 4 * Copyright 2007 rPath, Inc. - All Rights Reserved 5 * Copyright 2009 Intel Corporation; author H. Peter Anvin 6 * 7 * This file is part of the Linux kernel, and is made available under 8 * the terms of the GNU General Public License version 2. 9 * 10 * ----------------------------------------------------------------------- */ 11 12 /* 13 * Very simple screen and serial I/O 14 */ 15 16 #include "boot.h" 17 18 #define DEFAULT_SERIAL_PORT 0x3f8 /* ttyS0 */ 19 20 static int early_serial_base; 21 22 #define XMTRDY 0x20 23 24 #define DLAB 0x80 25 26 #define TXR 0 /* Transmit register (WRITE) */ 27 #define RXR 0 /* Receive register (READ) */ 28 #define IER 1 /* Interrupt Enable */ 29 #define IIR 2 /* Interrupt ID */ 30 #define FCR 2 /* FIFO control */ 31 #define LCR 3 /* Line control */ 32 #define MCR 4 /* Modem control */ 33 #define LSR 5 /* Line Status */ 34 #define MSR 6 /* Modem Status */ 35 #define DLL 0 /* Divisor Latch Low */ 36 #define DLH 1 /* Divisor latch High */ 37 38 #define DEFAULT_BAUD 9600 39 40 /* 41 * These functions are in .inittext so they can be used to signal 42 * error during initialization. 43 */ 44 45 static void __attribute__((section(".inittext"))) serial_putchar(int ch) 46 { 47 unsigned timeout = 0xffff; 48 49 while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout) 50 cpu_relax(); 51 52 outb(ch, early_serial_base + TXR); 53 } 54 55 static void __attribute__((section(".inittext"))) bios_putchar(int ch) 56 { 57 struct biosregs ireg; 58 59 initregs(&ireg); 60 ireg.bx = 0x0007; 61 ireg.cx = 0x0001; 62 ireg.ah = 0x0e; 63 ireg.al = ch; 64 intcall(0x10, &ireg, NULL); 65 } 66 67 void __attribute__((section(".inittext"))) putchar(int ch) 68 { 69 if (ch == '\n') 70 putchar('\r'); /* \n -> \r\n */ 71 72 bios_putchar(ch); 73 74 if (early_serial_base != 0) 75 serial_putchar(ch); 76 } 77 78 void __attribute__((section(".inittext"))) puts(const char *str) 79 { 80 while (*str) 81 putchar(*str++); 82 } 83 84 /* 85 * Read the CMOS clock through the BIOS, and return the 86 * seconds in BCD. 87 */ 88 89 static u8 gettime(void) 90 { 91 struct biosregs ireg, oreg; 92 93 initregs(&ireg); 94 ireg.ah = 0x02; 95 intcall(0x1a, &ireg, &oreg); 96 97 return oreg.dh; 98 } 99 100 /* 101 * Read from the keyboard 102 */ 103 int getchar(void) 104 { 105 struct biosregs ireg, oreg; 106 107 initregs(&ireg); 108 /* ireg.ah = 0x00; */ 109 intcall(0x16, &ireg, &oreg); 110 111 return oreg.al; 112 } 113 114 static int kbd_pending(void) 115 { 116 struct biosregs ireg, oreg; 117 118 initregs(&ireg); 119 ireg.ah = 0x01; 120 intcall(0x16, &ireg, &oreg); 121 122 return !(oreg.eflags & X86_EFLAGS_ZF); 123 } 124 125 void kbd_flush(void) 126 { 127 for (;;) { 128 if (!kbd_pending()) 129 break; 130 getchar(); 131 } 132 } 133 134 int getchar_timeout(void) 135 { 136 int cnt = 30; 137 int t0, t1; 138 139 t0 = gettime(); 140 141 while (cnt) { 142 if (kbd_pending()) 143 return getchar(); 144 145 t1 = gettime(); 146 if (t0 != t1) { 147 cnt--; 148 t0 = t1; 149 } 150 } 151 152 return 0; /* Timeout! */ 153 } 154 155 static void early_serial_init(int port, int baud) 156 { 157 unsigned char c; 158 unsigned divisor; 159 160 outb(0x3, port + LCR); /* 8n1 */ 161 outb(0, port + IER); /* no interrupt */ 162 outb(0, port + FCR); /* no fifo */ 163 outb(0x3, port + MCR); /* DTR + RTS */ 164 165 divisor = 115200 / baud; 166 c = inb(port + LCR); 167 outb(c | DLAB, port + LCR); 168 outb(divisor & 0xff, port + DLL); 169 outb((divisor >> 8) & 0xff, port + DLH); 170 outb(c & ~DLAB, port + LCR); 171 172 early_serial_base = port; 173 174 printf("Early serial console at I/O port 0x%x baud: %d\n", port, baud); 175 } 176 177 static void parse_earlyprintk(void) 178 { 179 int baud = DEFAULT_BAUD; 180 char arg[32]; 181 int pos = 0; 182 int port = 0; 183 184 if (cmdline_find_option("earlyprintk", arg, sizeof arg) > 0) { 185 char *e; 186 187 if (!strncmp(arg, "serial", 6)) { 188 port = DEFAULT_SERIAL_PORT; 189 pos += 6; 190 } 191 192 if (arg[pos] == ',') 193 pos++; 194 195 if (!strncmp(arg, "ttyS", 4)) { 196 static const int bases[] = { 0x3f8, 0x2f8 }; 197 int idx = 0; 198 199 if (!strncmp(arg + pos, "ttyS", 4)) 200 pos += 4; 201 202 if (arg[pos++] == '1') 203 idx = 1; 204 205 port = bases[idx]; 206 } 207 208 if (arg[pos] == ',') 209 pos++; 210 211 baud = simple_strtoull(arg + pos, &e, 0); 212 if (baud == 0 || arg + pos == e) 213 baud = DEFAULT_BAUD; 214 } 215 216 if (port) 217 early_serial_init(port, baud); 218 } 219 220 #define BASE_BAUD (1843200/16) 221 static unsigned int probe_baud(int port) 222 { 223 unsigned char lcr, dll, dlh; 224 unsigned int quot; 225 226 lcr = inb(port + LCR); 227 outb(lcr | DLAB, port + LCR); 228 dll = inb(port + DLL); 229 dlh = inb(port + DLH); 230 outb(lcr, port + LCR); 231 quot = (dlh << 8) | dll; 232 233 return BASE_BAUD / quot; 234 } 235 236 static void parse_console_uart8250(void) 237 { 238 char optstr[64], *options; 239 int baud = DEFAULT_BAUD; 240 int port = 0; 241 242 /* 243 * console=uart8250,io,0x3f8,115200n8 244 * need to make sure it is last one console ! 245 */ 246 if (cmdline_find_option("console", optstr, sizeof optstr) <= 0) 247 return; 248 249 options = optstr; 250 251 if (!strncmp(options, "uart8250,io,", 12)) 252 port = simple_strtoull(options + 12, &options, 0); 253 else if (!strncmp(options, "uart,io,", 8)) 254 port = simple_strtoull(options + 8, &options, 0); 255 else 256 return; 257 258 if (options && (options[0] == ',')) 259 baud = simple_strtoull(options + 1, &options, 0); 260 else 261 baud = probe_baud(port); 262 263 if (port) 264 early_serial_init(port, baud); 265 } 266 267 void console_init(void) 268 { 269 parse_earlyprintk(); 270 271 if (!early_serial_base) 272 parse_console_uart8250(); 273 } 274