cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
Log | Files | Refs | README | LICENSE | sfeed.txt

early_serial_console.c (3581B)

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