1 #include "boot.h" 2 3 #define DEFAULT_SERIAL_PORT 0x3f8 /* ttyS0 */ 4 5 #define XMTRDY 0x20 6 7 #define DLAB 0x80 8 9 #define TXR 0 /* Transmit register (WRITE) */ 10 #define RXR 0 /* Receive register (READ) */ 11 #define IER 1 /* Interrupt Enable */ 12 #define IIR 2 /* Interrupt ID */ 13 #define FCR 2 /* FIFO control */ 14 #define LCR 3 /* Line control */ 15 #define MCR 4 /* Modem control */ 16 #define LSR 5 /* Line Status */ 17 #define MSR 6 /* Modem Status */ 18 #define DLL 0 /* Divisor Latch Low */ 19 #define DLH 1 /* Divisor latch High */ 20 21 #define DEFAULT_BAUD 9600 22 23 static void early_serial_init(int port, int baud) 24 { 25 unsigned char c; 26 unsigned divisor; 27 28 outb(0x3, port + LCR); /* 8n1 */ 29 outb(0, port + IER); /* no interrupt */ 30 outb(0, port + FCR); /* no fifo */ 31 outb(0x3, port + MCR); /* DTR + RTS */ 32 33 divisor = 115200 / baud; 34 c = inb(port + LCR); 35 outb(c | DLAB, port + LCR); 36 outb(divisor & 0xff, port + DLL); 37 outb((divisor >> 8) & 0xff, port + DLH); 38 outb(c & ~DLAB, port + LCR); 39 40 early_serial_base = port; 41 } 42 43 static void parse_earlyprintk(void) 44 { 45 int baud = DEFAULT_BAUD; 46 char arg[32]; 47 int pos = 0; 48 int port = 0; 49 50 if (cmdline_find_option("earlyprintk", arg, sizeof arg) > 0) { 51 char *e; 52 53 if (!strncmp(arg, "serial", 6)) { 54 port = DEFAULT_SERIAL_PORT; 55 pos += 6; 56 } 57 58 if (arg[pos] == ',') 59 pos++; 60 61 if (!strncmp(arg, "ttyS", 4)) { 62 static const int bases[] = { 0x3f8, 0x2f8 }; 63 int idx = 0; 64 65 if (!strncmp(arg + pos, "ttyS", 4)) 66 pos += 4; 67 68 if (arg[pos++] == '1') 69 idx = 1; 70 71 port = bases[idx]; 72 } 73 74 if (arg[pos] == ',') 75 pos++; 76 77 baud = simple_strtoull(arg + pos, &e, 0); 78 if (baud == 0 || arg + pos == e) 79 baud = DEFAULT_BAUD; 80 } 81 82 if (port) 83 early_serial_init(port, baud); 84 } 85 86 #define BASE_BAUD (1843200/16) 87 static unsigned int probe_baud(int port) 88 { 89 unsigned char lcr, dll, dlh; 90 unsigned int quot; 91 92 lcr = inb(port + LCR); 93 outb(lcr | DLAB, port + LCR); 94 dll = inb(port + DLL); 95 dlh = inb(port + DLH); 96 outb(lcr, port + LCR); 97 quot = (dlh << 8) | dll; 98 99 return BASE_BAUD / quot; 100 } 101 102 static void parse_console_uart8250(void) 103 { 104 char optstr[64], *options; 105 int baud = DEFAULT_BAUD; 106 int port = 0; 107 108 /* 109 * console=uart8250,io,0x3f8,115200n8 110 * need to make sure it is last one console ! 111 */ 112 if (cmdline_find_option("console", optstr, sizeof optstr) <= 0) 113 return; 114 115 options = optstr; 116 117 if (!strncmp(options, "uart8250,io,", 12)) 118 port = simple_strtoull(options + 12, &options, 0); 119 else if (!strncmp(options, "uart,io,", 8)) 120 port = simple_strtoull(options + 8, &options, 0); 121 else 122 return; 123 124 if (options && (options[0] == ',')) 125 baud = simple_strtoull(options + 1, &options, 0); 126 else 127 baud = probe_baud(port); 128 129 if (port) 130 early_serial_init(port, baud); 131 } 132 133 void console_init(void) 134 { 135 parse_earlyprintk(); 136 137 if (!early_serial_base) 138 parse_console_uart8250(); 139 } 140