src/superio/smsc/sio1007/early_serial.c

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2
   3 #include <stdint.h>
   4 #include <arch/io.h>
   5 #include "sio1007.h"
   6
   7 void sio1007_setreg(u16 lpc_port, u8 reg, u8 value, u8 mask)
   8 {
   9         u8 reg_value;
  10
  11         outb(reg, lpc_port);
  12         reg_value = inb(lpc_port + 1);
  13         reg_value &= ~mask;
  14         reg_value |= (value & mask);
  15         outb(reg_value, lpc_port + 1);
  16 }
  17
  18 int sio1007_enable_uart_at(u16 port)
  19 {
  20         /* Enable config mode. */
  21         outb(0x55, port);
  22         if (inb(port) != 0x55)
  23                 return 0; /* There is no LPC device at this address. */
  24
  25         /* Registers 12 and 13 hold config address, look for a match. */
  26         outb(0x12, port);
  27         if (inb(port + 1) != (port & 0xff))
  28                 return 0;
  29
  30         outb(0x13, port);
  31         if (inb(port + 1) != (port >> 8))
  32                 return 0;
  33
  34         /* This must be the sio1007, enable the UART. */
  35         /* turn on power */
  36         sio1007_setreg(port, 0x2, 1 << 3, 1 << 3);
  37         /* enable high speed */
  38         sio1007_setreg(port, 0xc, 1 << 6, 1 << 6);
  39         /* set the base address */
  40         sio1007_setreg(port, 0x24, CONFIG_TTYS0_BASE >> 2, 0xff);
  41
  42         /* Disable config mode. */
  43         outb(0xaa, port);
  44         return 1;
  45 }