1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Serial port routines for use during early boot reporting. This code is
4*4882a593Smuzhiyun * included from both the compressed kernel and the regular kernel.
5*4882a593Smuzhiyun */
6*4882a593Smuzhiyun #include "boot.h"
7*4882a593Smuzhiyun
8*4882a593Smuzhiyun #define DEFAULT_SERIAL_PORT 0x3f8 /* ttyS0 */
9*4882a593Smuzhiyun
10*4882a593Smuzhiyun #define DLAB 0x80
11*4882a593Smuzhiyun
12*4882a593Smuzhiyun #define TXR 0 /* Transmit register (WRITE) */
13*4882a593Smuzhiyun #define RXR 0 /* Receive register (READ) */
14*4882a593Smuzhiyun #define IER 1 /* Interrupt Enable */
15*4882a593Smuzhiyun #define IIR 2 /* Interrupt ID */
16*4882a593Smuzhiyun #define FCR 2 /* FIFO control */
17*4882a593Smuzhiyun #define LCR 3 /* Line control */
18*4882a593Smuzhiyun #define MCR 4 /* Modem control */
19*4882a593Smuzhiyun #define LSR 5 /* Line Status */
20*4882a593Smuzhiyun #define MSR 6 /* Modem Status */
21*4882a593Smuzhiyun #define DLL 0 /* Divisor Latch Low */
22*4882a593Smuzhiyun #define DLH 1 /* Divisor latch High */
23*4882a593Smuzhiyun
24*4882a593Smuzhiyun #define DEFAULT_BAUD 9600
25*4882a593Smuzhiyun
early_serial_init(int port,int baud)26*4882a593Smuzhiyun static void early_serial_init(int port, int baud)
27*4882a593Smuzhiyun {
28*4882a593Smuzhiyun unsigned char c;
29*4882a593Smuzhiyun unsigned divisor;
30*4882a593Smuzhiyun
31*4882a593Smuzhiyun outb(0x3, port + LCR); /* 8n1 */
32*4882a593Smuzhiyun outb(0, port + IER); /* no interrupt */
33*4882a593Smuzhiyun outb(0, port + FCR); /* no fifo */
34*4882a593Smuzhiyun outb(0x3, port + MCR); /* DTR + RTS */
35*4882a593Smuzhiyun
36*4882a593Smuzhiyun divisor = 115200 / baud;
37*4882a593Smuzhiyun c = inb(port + LCR);
38*4882a593Smuzhiyun outb(c | DLAB, port + LCR);
39*4882a593Smuzhiyun outb(divisor & 0xff, port + DLL);
40*4882a593Smuzhiyun outb((divisor >> 8) & 0xff, port + DLH);
41*4882a593Smuzhiyun outb(c & ~DLAB, port + LCR);
42*4882a593Smuzhiyun
43*4882a593Smuzhiyun early_serial_base = port;
44*4882a593Smuzhiyun }
45*4882a593Smuzhiyun
parse_earlyprintk(void)46*4882a593Smuzhiyun static void parse_earlyprintk(void)
47*4882a593Smuzhiyun {
48*4882a593Smuzhiyun int baud = DEFAULT_BAUD;
49*4882a593Smuzhiyun char arg[32];
50*4882a593Smuzhiyun int pos = 0;
51*4882a593Smuzhiyun int port = 0;
52*4882a593Smuzhiyun
53*4882a593Smuzhiyun if (cmdline_find_option("earlyprintk", arg, sizeof(arg)) > 0) {
54*4882a593Smuzhiyun char *e;
55*4882a593Smuzhiyun
56*4882a593Smuzhiyun if (!strncmp(arg, "serial", 6)) {
57*4882a593Smuzhiyun port = DEFAULT_SERIAL_PORT;
58*4882a593Smuzhiyun pos += 6;
59*4882a593Smuzhiyun }
60*4882a593Smuzhiyun
61*4882a593Smuzhiyun if (arg[pos] == ',')
62*4882a593Smuzhiyun pos++;
63*4882a593Smuzhiyun
64*4882a593Smuzhiyun /*
65*4882a593Smuzhiyun * make sure we have
66*4882a593Smuzhiyun * "serial,0x3f8,115200"
67*4882a593Smuzhiyun * "serial,ttyS0,115200"
68*4882a593Smuzhiyun * "ttyS0,115200"
69*4882a593Smuzhiyun */
70*4882a593Smuzhiyun if (pos == 7 && !strncmp(arg + pos, "0x", 2)) {
71*4882a593Smuzhiyun port = simple_strtoull(arg + pos, &e, 16);
72*4882a593Smuzhiyun if (port == 0 || arg + pos == e)
73*4882a593Smuzhiyun port = DEFAULT_SERIAL_PORT;
74*4882a593Smuzhiyun else
75*4882a593Smuzhiyun pos = e - arg;
76*4882a593Smuzhiyun } else if (!strncmp(arg + pos, "ttyS", 4)) {
77*4882a593Smuzhiyun static const int bases[] = { 0x3f8, 0x2f8 };
78*4882a593Smuzhiyun int idx = 0;
79*4882a593Smuzhiyun
80*4882a593Smuzhiyun /* += strlen("ttyS"); */
81*4882a593Smuzhiyun pos += 4;
82*4882a593Smuzhiyun
83*4882a593Smuzhiyun if (arg[pos++] == '1')
84*4882a593Smuzhiyun idx = 1;
85*4882a593Smuzhiyun
86*4882a593Smuzhiyun port = bases[idx];
87*4882a593Smuzhiyun }
88*4882a593Smuzhiyun
89*4882a593Smuzhiyun if (arg[pos] == ',')
90*4882a593Smuzhiyun pos++;
91*4882a593Smuzhiyun
92*4882a593Smuzhiyun baud = simple_strtoull(arg + pos, &e, 0);
93*4882a593Smuzhiyun if (baud == 0 || arg + pos == e)
94*4882a593Smuzhiyun baud = DEFAULT_BAUD;
95*4882a593Smuzhiyun }
96*4882a593Smuzhiyun
97*4882a593Smuzhiyun if (port)
98*4882a593Smuzhiyun early_serial_init(port, baud);
99*4882a593Smuzhiyun }
100*4882a593Smuzhiyun
101*4882a593Smuzhiyun #define BASE_BAUD (1843200/16)
probe_baud(int port)102*4882a593Smuzhiyun static unsigned int probe_baud(int port)
103*4882a593Smuzhiyun {
104*4882a593Smuzhiyun unsigned char lcr, dll, dlh;
105*4882a593Smuzhiyun unsigned int quot;
106*4882a593Smuzhiyun
107*4882a593Smuzhiyun lcr = inb(port + LCR);
108*4882a593Smuzhiyun outb(lcr | DLAB, port + LCR);
109*4882a593Smuzhiyun dll = inb(port + DLL);
110*4882a593Smuzhiyun dlh = inb(port + DLH);
111*4882a593Smuzhiyun outb(lcr, port + LCR);
112*4882a593Smuzhiyun quot = (dlh << 8) | dll;
113*4882a593Smuzhiyun
114*4882a593Smuzhiyun return BASE_BAUD / quot;
115*4882a593Smuzhiyun }
116*4882a593Smuzhiyun
parse_console_uart8250(void)117*4882a593Smuzhiyun static void parse_console_uart8250(void)
118*4882a593Smuzhiyun {
119*4882a593Smuzhiyun char optstr[64], *options;
120*4882a593Smuzhiyun int baud = DEFAULT_BAUD;
121*4882a593Smuzhiyun int port = 0;
122*4882a593Smuzhiyun
123*4882a593Smuzhiyun /*
124*4882a593Smuzhiyun * console=uart8250,io,0x3f8,115200n8
125*4882a593Smuzhiyun * need to make sure it is last one console !
126*4882a593Smuzhiyun */
127*4882a593Smuzhiyun if (cmdline_find_option("console", optstr, sizeof(optstr)) <= 0)
128*4882a593Smuzhiyun return;
129*4882a593Smuzhiyun
130*4882a593Smuzhiyun options = optstr;
131*4882a593Smuzhiyun
132*4882a593Smuzhiyun if (!strncmp(options, "uart8250,io,", 12))
133*4882a593Smuzhiyun port = simple_strtoull(options + 12, &options, 0);
134*4882a593Smuzhiyun else if (!strncmp(options, "uart,io,", 8))
135*4882a593Smuzhiyun port = simple_strtoull(options + 8, &options, 0);
136*4882a593Smuzhiyun else
137*4882a593Smuzhiyun return;
138*4882a593Smuzhiyun
139*4882a593Smuzhiyun if (options && (options[0] == ','))
140*4882a593Smuzhiyun baud = simple_strtoull(options + 1, &options, 0);
141*4882a593Smuzhiyun else
142*4882a593Smuzhiyun baud = probe_baud(port);
143*4882a593Smuzhiyun
144*4882a593Smuzhiyun if (port)
145*4882a593Smuzhiyun early_serial_init(port, baud);
146*4882a593Smuzhiyun }
147*4882a593Smuzhiyun
console_init(void)148*4882a593Smuzhiyun void console_init(void)
149*4882a593Smuzhiyun {
150*4882a593Smuzhiyun parse_earlyprintk();
151*4882a593Smuzhiyun
152*4882a593Smuzhiyun if (!early_serial_base)
153*4882a593Smuzhiyun parse_console_uart8250();
154*4882a593Smuzhiyun }
155