1 /* 2 * Serial port routines for use during early boot reporting. This code is 3 * included from both the compressed kernel and the regular kernel. 4 */ 5 #include "boot.h" 6 7 #define DEFAULT_SERIAL_PORT 0x3f8 /* ttyS0 */ 8 9 #define DLAB 0x80 10 11 #define TXR 0 /* Transmit register (WRITE) */ 12 #define RXR 0 /* Receive register (READ) */ 13 #define IER 1 /* Interrupt Enable */ 14 #define IIR 2 /* Interrupt ID */ 15 #define FCR 2 /* FIFO control */ 16 #define LCR 3 /* Line control */ 17 #define MCR 4 /* Modem control */ 18 #define LSR 5 /* Line Status */ 19 #define MSR 6 /* Modem Status */ 20 #define DLL 0 /* Divisor Latch Low */ 21 #define DLH 1 /* Divisor latch High */ 22 23 #define DEFAULT_BAUD 9600 24 25 static void early_serial_init(int port, int baud) 26 { 27 unsigned char c; 28 unsigned divisor; 29 30 outb(0x3, port + LCR); /* 8n1 */ 31 outb(0, port + IER); /* no interrupt */ 32 outb(0, port + FCR); /* no fifo */ 33 outb(0x3, port + MCR); /* DTR + RTS */ 34 35 divisor = 115200 / baud; 36 c = inb(port + LCR); 37 outb(c | DLAB, port + LCR); 38 outb(divisor & 0xff, port + DLL); 39 outb((divisor >> 8) & 0xff, port + DLH); 40 outb(c & ~DLAB, port + LCR); 41 42 early_serial_base = port; 43 } 44 45 static void parse_earlyprintk(void) 46 { 47 int baud = DEFAULT_BAUD; 48 char arg[32]; 49 int pos = 0; 50 int port = 0; 51 52 if (cmdline_find_option("earlyprintk", arg, sizeof arg) > 0) { 53 char *e; 54 55 if (!strncmp(arg, "serial", 6)) { 56 port = DEFAULT_SERIAL_PORT; 57 pos += 6; 58 } 59 60 if (arg[pos] == ',') 61 pos++; 62 63 /* 64 * make sure we have 65 * "serial,0x3f8,115200" 66 * "serial,ttyS0,115200" 67 * "ttyS0,115200" 68 */ 69 if (pos == 7 && !strncmp(arg + pos, "0x", 2)) { 70 port = simple_strtoull(arg + pos, &e, 16); 71 if (port == 0 || arg + pos == e) 72 port = DEFAULT_SERIAL_PORT; 73 else 74 pos = e - arg; 75 } else if (!strncmp(arg + pos, "ttyS", 4)) { 76 static const int bases[] = { 0x3f8, 0x2f8 }; 77 int idx = 0; 78 79 /* += strlen("ttyS"); */ 80 pos += 4; 81 82 if (arg[pos++] == '1') 83 idx = 1; 84 85 port = bases[idx]; 86 } 87 88 if (arg[pos] == ',') 89 pos++; 90 91 baud = simple_strtoull(arg + pos, &e, 0); 92 if (baud == 0 || arg + pos == e) 93 baud = DEFAULT_BAUD; 94 } 95 96 if (port) 97 early_serial_init(port, baud); 98 } 99 100 #define BASE_BAUD (1843200/16) 101 static unsigned int probe_baud(int port) 102 { 103 unsigned char lcr, dll, dlh; 104 unsigned int quot; 105 106 lcr = inb(port + LCR); 107 outb(lcr | DLAB, port + LCR); 108 dll = inb(port + DLL); 109 dlh = inb(port + DLH); 110 outb(lcr, port + LCR); 111 quot = (dlh << 8) | dll; 112 113 return BASE_BAUD / quot; 114 } 115 116 static void parse_console_uart8250(void) 117 { 118 char optstr[64], *options; 119 int baud = DEFAULT_BAUD; 120 int port = 0; 121 122 /* 123 * console=uart8250,io,0x3f8,115200n8 124 * need to make sure it is last one console ! 125 */ 126 if (cmdline_find_option("console", optstr, sizeof optstr) <= 0) 127 return; 128 129 options = optstr; 130 131 if (!strncmp(options, "uart8250,io,", 12)) 132 port = simple_strtoull(options + 12, &options, 0); 133 else if (!strncmp(options, "uart,io,", 8)) 134 port = simple_strtoull(options + 8, &options, 0); 135 else 136 return; 137 138 if (options && (options[0] == ',')) 139 baud = simple_strtoull(options + 1, &options, 0); 140 else 141 baud = probe_baud(port); 142 143 if (port) 144 early_serial_init(port, baud); 145 } 146 147 void console_init(void) 148 { 149 parse_earlyprintk(); 150 151 if (!early_serial_base) 152 parse_console_uart8250(); 153 } 154