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 		/*
62 		 * make sure we have
63 		 *	"serial,0x3f8,115200"
64 		 *	"serial,ttyS0,115200"
65 		 *	"ttyS0,115200"
66 		 */
67 		if (pos == 7 && !strncmp(arg + pos, "0x", 2)) {
68 			port = simple_strtoull(arg + pos, &e, 16);
69 			if (port == 0 || arg + pos == e)
70 				port = DEFAULT_SERIAL_PORT;
71 			else
72 				pos = e - arg;
73 		} else if (!strncmp(arg + pos, "ttyS", 4)) {
74 			static const int bases[] = { 0x3f8, 0x2f8 };
75 			int idx = 0;
76 
77 			if (!strncmp(arg + pos, "ttyS", 4))
78 				pos += 4;
79 
80 			if (arg[pos++] == '1')
81 				idx = 1;
82 
83 			port = bases[idx];
84 		}
85 
86 		if (arg[pos] == ',')
87 			pos++;
88 
89 		baud = simple_strtoull(arg + pos, &e, 0);
90 		if (baud == 0 || arg + pos == e)
91 			baud = DEFAULT_BAUD;
92 	}
93 
94 	if (port)
95 		early_serial_init(port, baud);
96 }
97 
98 #define BASE_BAUD (1843200/16)
99 static unsigned int probe_baud(int port)
100 {
101 	unsigned char lcr, dll, dlh;
102 	unsigned int quot;
103 
104 	lcr = inb(port + LCR);
105 	outb(lcr | DLAB, port + LCR);
106 	dll = inb(port + DLL);
107 	dlh = inb(port + DLH);
108 	outb(lcr, port + LCR);
109 	quot = (dlh << 8) | dll;
110 
111 	return BASE_BAUD / quot;
112 }
113 
114 static void parse_console_uart8250(void)
115 {
116 	char optstr[64], *options;
117 	int baud = DEFAULT_BAUD;
118 	int port = 0;
119 
120 	/*
121 	 * console=uart8250,io,0x3f8,115200n8
122 	 * need to make sure it is last one console !
123 	 */
124 	if (cmdline_find_option("console", optstr, sizeof optstr) <= 0)
125 		return;
126 
127 	options = optstr;
128 
129 	if (!strncmp(options, "uart8250,io,", 12))
130 		port = simple_strtoull(options + 12, &options, 0);
131 	else if (!strncmp(options, "uart,io,", 8))
132 		port = simple_strtoull(options + 8, &options, 0);
133 	else
134 		return;
135 
136 	if (options && (options[0] == ','))
137 		baud = simple_strtoull(options + 1, &options, 0);
138 	else
139 		baud = probe_baud(port);
140 
141 	if (port)
142 		early_serial_init(port, baud);
143 }
144 
145 void console_init(void)
146 {
147 	parse_earlyprintk();
148 
149 	if (!early_serial_base)
150 		parse_console_uart8250();
151 }
152