LXR syslinux/memdump/serial.c

   1#include <stdbool.h>
   2#include <stdio.h>
   3
   4#include "mystuff.h"
   5#include "file.h"
   6#include "io.h"
   7
   8enum {
   9    THR = 0,
  10    RBR = 0,
  11    DLL = 0,
  12    DLM = 1,
  13    IER = 1,
  14    IIR = 2,
  15    FCR = 2,
  16    LCR = 3,
  17    MCR = 4,
  18    LSR = 5,
  19    MSR = 6,
  20    SCR = 7,
  21};
  22
  23int serial_init(struct serial_if *sif)
  24{
  25    uint16_t port = sif->port;
  26    uint8_t dll, dlm, lcr;
  27
  28    /* Set 115200n81 */
  29    outb(0x83, port + LCR);
  30    outb(0x01, port + DLL);
  31    outb(0x00, port + DLM);
  32    (void)inb(port + IER);      /* Synchronize */
  33    dll = inb(port + DLL);
  34    dlm = inb(port + DLM);
  35    lcr = inb(port + LCR);
  36    outb(0x03, port + LCR);
  37    (void)inb(port + IER);      /* Synchronize */
  38
  39    if (dll != 0x01 || dlm != 0x00 || lcr != 0x83)
  40        return -1;              /* This doesn't look like a serial port */
  41
  42    /* Disable interrupts */
  43    outb(port + IER, 0);
  44
  45    /* Enable 16550A FIFOs if available */
  46    outb(port + FCR, 0x01);     /* Enable FIFO */
  47    (void)inb(port + IER);      /* Synchronize */
  48    if (inb(port + IIR) < 0xc0)
  49        outb(port + FCR, 0x00); /* Disable FIFOs if non-functional */
  50    (void)inb(port + IER);      /* Synchronize */
  51
  52    return 0;
  53}
  54
  55void serial_write(struct serial_if *sif, const void *data, size_t n)
  56{
  57    uint16_t port = sif->port;
  58    const char *p = data;
  59    uint8_t lsr;
  60
  61    while (n--) {
  62        do {
  63            lsr = inb(port + LSR);
  64        } while (!(lsr & 0x20));
  65
  66        outb(*p++, port + THR);
  67    }
  68}
  69
  70void serial_read(struct serial_if *sif, void *data, size_t n)
  71{
  72    uint16_t port = sif->port;
  73    char *p = data;
  74    uint8_t lsr;
  75
  76    while (n--) {
  77        do {
  78            lsr = inb(port + LSR);
  79        } while (!(lsr & 0x01));
  80
  81        *p++ = inb(port + RBR);
  82    }
  83}
  84