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
21static 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
41static 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)
97static 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
112static 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
143void console_init(void)
144{
145	parse_earlyprintk();
146
147	if (!early_serial_base)
148		parse_console_uart8250();
149}
150