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Draft attempt at autocons utility

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Make every effort to do early boot console enablement.
This commit is contained in:
Jarrod Johnson 2019-03-12 19:31:16 -04:00
parent a258653186
commit c5fa0bfd79
1 changed files with 76 additions and 0 deletions
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misc/autocons.c Normal file
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#include <termios.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#define COM1 0x3f8
#define COM2 0x2f8
#define COM3 0x3e8
#define COM4 0x2e8
#define SPEEDNOOP 0
#define SPEED9600 3
#define SPEED19200 4
#define SPEED57600 6
#define SPEED115200 7
int main(int argc, char* argv[]) {
struct termios tty;
int ttyf;
int spcr;
int currspeed;
speed_t cspeed;
char buff[128];
uint64_t address;
spcr = open("/sys/firmware/acpi/tables/SPCR", O_RDONLY);
if (spcr < 0) {
exit(0);
}
if (read(spcr, buff, 80) < 80) {
exit(0);
}
if (buff[8] != 2) exit(0); //revision 2
if (buff[36] != 0) exit(0); //16550 only
if (buff[40] != 1) exit(0); //IO only
address = *(uint64_t *)(buff + 44);
currspeed = buff[58];
if (address == COM1) {
strncpy(buff, "/dev/ttyS0", 128);
} else if (address == COM2) {
strncpy(buff, "/dev/ttyS1", 128);
} else if (address == COM3) {
strncpy(buff, "/dev/ttyS2", 128);
} else if (address == COM4) {
strncpy(buff, "/dev/ttyS3", 128);
} else {
exit(0);
}
if (currspeed == SPEED9600) {
cspeed = B9600;
} else if (currspeed == SPEED19200) {
cspeed = B19200;
} else if (currspeed == SPEED57600) {
cspeed = B57600;
} else if (currspeed == SPEED115200) {
cspeed = B115200;
} else if (currspeed == SPEED115200) {
cspeed = 0;
} else {
exit(0);
}
printf("%s\n", buff);
ttyf = open(buff, O_RDWR | O_NOCTTY);
tcgetattr(ttyf, &tty);
if (cspeed) {
cfsetospeed(&tty, B115200);
cfsetispeed(&tty, B115200);
}
tcsetattr(ttyf, TCSANOW, &tty);
ioctl(ttyf, TIOCCONS, 0);
}