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
   8 enum {
   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
  23 int 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
  55 void 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
  70 void 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 }