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