1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0
2cb18ef0dSKees Cook /*
3cb18ef0dSKees Cook * Serial port routines for use during early boot reporting. This code is
4cb18ef0dSKees Cook * included from both the compressed kernel and the regular kernel.
5cb18ef0dSKees Cook */
6f4ed2877SYinghai Lu #include "boot.h"
7f4ed2877SYinghai Lu
8f4ed2877SYinghai Lu #define DEFAULT_SERIAL_PORT 0x3f8 /* ttyS0 */
9f4ed2877SYinghai Lu
10f4ed2877SYinghai Lu #define DLAB 0x80
11f4ed2877SYinghai Lu
12f4ed2877SYinghai Lu #define TXR 0 /* Transmit register (WRITE) */
13f4ed2877SYinghai Lu #define RXR 0 /* Receive register (READ) */
14f4ed2877SYinghai Lu #define IER 1 /* Interrupt Enable */
15f4ed2877SYinghai Lu #define IIR 2 /* Interrupt ID */
16f4ed2877SYinghai Lu #define FCR 2 /* FIFO control */
17f4ed2877SYinghai Lu #define LCR 3 /* Line control */
18f4ed2877SYinghai Lu #define MCR 4 /* Modem control */
19f4ed2877SYinghai Lu #define LSR 5 /* Line Status */
20f4ed2877SYinghai Lu #define MSR 6 /* Modem Status */
21f4ed2877SYinghai Lu #define DLL 0 /* Divisor Latch Low */
22f4ed2877SYinghai Lu #define DLH 1 /* Divisor latch High */
23f4ed2877SYinghai Lu
24f4ed2877SYinghai Lu #define DEFAULT_BAUD 9600
25f4ed2877SYinghai Lu
early_serial_init(int port,int baud)26f4ed2877SYinghai Lu static void early_serial_init(int port, int baud)
27f4ed2877SYinghai Lu {
28f4ed2877SYinghai Lu unsigned char c;
29f4ed2877SYinghai Lu unsigned divisor;
30f4ed2877SYinghai Lu
31f4ed2877SYinghai Lu outb(0x3, port + LCR); /* 8n1 */
32f4ed2877SYinghai Lu outb(0, port + IER); /* no interrupt */
33f4ed2877SYinghai Lu outb(0, port + FCR); /* no fifo */
34f4ed2877SYinghai Lu outb(0x3, port + MCR); /* DTR + RTS */
35f4ed2877SYinghai Lu
36f4ed2877SYinghai Lu divisor = 115200 / baud;
37f4ed2877SYinghai Lu c = inb(port + LCR);
38f4ed2877SYinghai Lu outb(c | DLAB, port + LCR);
39f4ed2877SYinghai Lu outb(divisor & 0xff, port + DLL);
40f4ed2877SYinghai Lu outb((divisor >> 8) & 0xff, port + DLH);
41f4ed2877SYinghai Lu outb(c & ~DLAB, port + LCR);
42f4ed2877SYinghai Lu
43f4ed2877SYinghai Lu early_serial_base = port;
44f4ed2877SYinghai Lu }
45f4ed2877SYinghai Lu
parse_earlyprintk(void)46f4ed2877SYinghai Lu static void parse_earlyprintk(void)
47f4ed2877SYinghai Lu {
48f4ed2877SYinghai Lu int baud = DEFAULT_BAUD;
49f4ed2877SYinghai Lu char arg[32];
50f4ed2877SYinghai Lu int pos = 0;
51f4ed2877SYinghai Lu int port = 0;
52f4ed2877SYinghai Lu
530e96f31eSJordan Borgner if (cmdline_find_option("earlyprintk", arg, sizeof(arg)) > 0) {
54f4ed2877SYinghai Lu char *e;
55f4ed2877SYinghai Lu
56f4ed2877SYinghai Lu if (!strncmp(arg, "serial", 6)) {
57f4ed2877SYinghai Lu port = DEFAULT_SERIAL_PORT;
58f4ed2877SYinghai Lu pos += 6;
59f4ed2877SYinghai Lu }
60f4ed2877SYinghai Lu
61f4ed2877SYinghai Lu if (arg[pos] == ',')
62f4ed2877SYinghai Lu pos++;
63f4ed2877SYinghai Lu
6474b3c444SYinghai Lu /*
6574b3c444SYinghai Lu * make sure we have
6674b3c444SYinghai Lu * "serial,0x3f8,115200"
6774b3c444SYinghai Lu * "serial,ttyS0,115200"
6874b3c444SYinghai Lu * "ttyS0,115200"
6974b3c444SYinghai Lu */
7074b3c444SYinghai Lu if (pos == 7 && !strncmp(arg + pos, "0x", 2)) {
7174b3c444SYinghai Lu port = simple_strtoull(arg + pos, &e, 16);
7274b3c444SYinghai Lu if (port == 0 || arg + pos == e)
7374b3c444SYinghai Lu port = DEFAULT_SERIAL_PORT;
7474b3c444SYinghai Lu else
7574b3c444SYinghai Lu pos = e - arg;
7674b3c444SYinghai Lu } else if (!strncmp(arg + pos, "ttyS", 4)) {
77f4ed2877SYinghai Lu static const int bases[] = { 0x3f8, 0x2f8 };
78f4ed2877SYinghai Lu int idx = 0;
79f4ed2877SYinghai Lu
80b3463001SAlexander Kuleshov /* += strlen("ttyS"); */
81f4ed2877SYinghai Lu pos += 4;
82f4ed2877SYinghai Lu
83f4ed2877SYinghai Lu if (arg[pos++] == '1')
84f4ed2877SYinghai Lu idx = 1;
85f4ed2877SYinghai Lu
86f4ed2877SYinghai Lu port = bases[idx];
87f4ed2877SYinghai Lu }
88f4ed2877SYinghai Lu
89f4ed2877SYinghai Lu if (arg[pos] == ',')
90f4ed2877SYinghai Lu pos++;
91f4ed2877SYinghai Lu
92f4ed2877SYinghai Lu baud = simple_strtoull(arg + pos, &e, 0);
93f4ed2877SYinghai Lu if (baud == 0 || arg + pos == e)
94f4ed2877SYinghai Lu baud = DEFAULT_BAUD;
95f4ed2877SYinghai Lu }
96f4ed2877SYinghai Lu
97f4ed2877SYinghai Lu if (port)
98f4ed2877SYinghai Lu early_serial_init(port, baud);
99f4ed2877SYinghai Lu }
100f4ed2877SYinghai Lu
101f4ed2877SYinghai Lu #define BASE_BAUD (1843200/16)
probe_baud(int port)102f4ed2877SYinghai Lu static unsigned int probe_baud(int port)
103f4ed2877SYinghai Lu {
104f4ed2877SYinghai Lu unsigned char lcr, dll, dlh;
105f4ed2877SYinghai Lu unsigned int quot;
106f4ed2877SYinghai Lu
107f4ed2877SYinghai Lu lcr = inb(port + LCR);
108f4ed2877SYinghai Lu outb(lcr | DLAB, port + LCR);
109f4ed2877SYinghai Lu dll = inb(port + DLL);
110f4ed2877SYinghai Lu dlh = inb(port + DLH);
111f4ed2877SYinghai Lu outb(lcr, port + LCR);
112f4ed2877SYinghai Lu quot = (dlh << 8) | dll;
113f4ed2877SYinghai Lu
114f4ed2877SYinghai Lu return BASE_BAUD / quot;
115f4ed2877SYinghai Lu }
116f4ed2877SYinghai Lu
parse_console_uart8250(void)117f4ed2877SYinghai Lu static void parse_console_uart8250(void)
118f4ed2877SYinghai Lu {
119f4ed2877SYinghai Lu char optstr[64], *options;
120f4ed2877SYinghai Lu int baud = DEFAULT_BAUD;
121f4ed2877SYinghai Lu int port = 0;
122f4ed2877SYinghai Lu
123f4ed2877SYinghai Lu /*
124f4ed2877SYinghai Lu * console=uart8250,io,0x3f8,115200n8
125f4ed2877SYinghai Lu * need to make sure it is last one console !
126f4ed2877SYinghai Lu */
1270e96f31eSJordan Borgner if (cmdline_find_option("console", optstr, sizeof(optstr)) <= 0)
128f4ed2877SYinghai Lu return;
129f4ed2877SYinghai Lu
130f4ed2877SYinghai Lu options = optstr;
131f4ed2877SYinghai Lu
132f4ed2877SYinghai Lu if (!strncmp(options, "uart8250,io,", 12))
133f4ed2877SYinghai Lu port = simple_strtoull(options + 12, &options, 0);
134f4ed2877SYinghai Lu else if (!strncmp(options, "uart,io,", 8))
135f4ed2877SYinghai Lu port = simple_strtoull(options + 8, &options, 0);
136f4ed2877SYinghai Lu else
137f4ed2877SYinghai Lu return;
138f4ed2877SYinghai Lu
139f4ed2877SYinghai Lu if (options && (options[0] == ','))
140f4ed2877SYinghai Lu baud = simple_strtoull(options + 1, &options, 0);
141f4ed2877SYinghai Lu else
142f4ed2877SYinghai Lu baud = probe_baud(port);
143f4ed2877SYinghai Lu
144f4ed2877SYinghai Lu if (port)
145f4ed2877SYinghai Lu early_serial_init(port, baud);
146f4ed2877SYinghai Lu }
147f4ed2877SYinghai Lu
console_init(void)148f4ed2877SYinghai Lu void console_init(void)
149f4ed2877SYinghai Lu {
150f4ed2877SYinghai Lu parse_earlyprintk();
151f4ed2877SYinghai Lu
152f4ed2877SYinghai Lu if (!early_serial_base)
153f4ed2877SYinghai Lu parse_console_uart8250();
154f4ed2877SYinghai Lu }
155