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gerrit-public.fairphone.software / kernel / msm-4.19 / 9ecd1c3d6cff05fcfd11517341cc22f61651ec3e / . / arch / x86 / boot / early_serial_console.c
blob: 5df2869c874baced33de00a78a7b693f3237ea0f [file] [log] [blame]
Yinghai Luf4ed2872010-08-02 02:17:31 -0700[diff] [blame]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
23static 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
43static 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
Yinghai Lu74b3c442010-08-29 18:13:10 -0700[diff] [blame]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)) {
Yinghai Luf4ed2872010-08-02 02:17:31 -0700[diff] [blame]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)
99static 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
114static 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
145void console_init(void)
146{
147 parse_earlyprintk();
148
149 if (!early_serial_base)
150 parse_console_uart8250();
151}