src/southbridge/via/vt8235/vt8235_early_serial.c

   1 /*
   2  * Enable the serial evices on the VIA
   3  */
   4
   5
   6 /* The base address is 0x15c, 0x2e, depending on config bytes */
   7
   8 #define SIO_BASE 0x3f0
   9 #define SIO_DATA  SIO_BASE+1
  10
  11 static void vt8235_writepnpaddr(uint8_t val)
  12 {
  13         outb(val, 0x2e);
  14         outb(val, 0xeb);
  15 }
  16
  17 static void vt8235_writepnpdata(uint8_t val)
  18 {
  19         outb(val, 0x2f);
  20         outb(val, 0xeb);
  21 }
  22
  23
  24 static void vt8235_writesiobyte(uint16_t reg, uint8_t val)
  25 {
  26         outb(val, reg);
  27 }
  28
  29 static void vt8235_writesioword(uint16_t reg, uint16_t val)
  30 {
  31         outw(val, reg);
  32 }
  33
  34
  35 /* regs we use: 85, and the southbridge devfn is defined by the
  36    mainboard
  37  */
  38
  39 static void enable_vt8235_serial(void)
  40 {
  41         // turn on pnp
  42         vt8235_writepnpaddr(0x87);
  43         vt8235_writepnpaddr(0x87);
  44         // now go ahead and set up com1.
  45         // set address
  46         vt8235_writepnpaddr(0x7);
  47         vt8235_writepnpdata(0x2);
  48         // enable serial out
  49         vt8235_writepnpaddr(0x30);
  50         vt8235_writepnpdata(0x1);
  51         // serial port 1 base address (FEh)
  52         vt8235_writepnpaddr(0x60);
  53         vt8235_writepnpdata(0xfe);
  54         // serial port 1 IRQ (04h)
  55         vt8235_writepnpaddr(0x70);
  56         vt8235_writepnpdata(0x4);
  57         // serial port 1 control
  58         vt8235_writepnpaddr(0xf0);
  59         vt8235_writepnpdata(0x2);
  60         // turn of pnp
  61         vt8235_writepnpaddr(0xaa);
  62
  63         // set up reg to set baud rate.
  64         vt8235_writesiobyte(0x3fb, 0x80);
  65         // Set 115 kb
  66         vt8235_writesioword(0x3f8, 1);
  67         // Set 9.6 kb
  68         //      WRITESIOWORD(0x3f8, 12)
  69         // now set no parity, one stop, 8 bits
  70         vt8235_writesiobyte(0x3fb, 3);
  71         // now turn on RTS, DRT
  72         vt8235_writesiobyte(0x3fc, 3);
  73         // Enable interrupts
  74         vt8235_writesiobyte(0x3f9, 0xf);
  75         // should be done. Dump a char for fun.
  76         vt8235_writesiobyte(0x3f8, 48);
  77 }