src/superio/smsc/smscsuperio/early_serial.c

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2
   3 #include <arch/io.h>
   4 #include <device/pnp_ops.h>
   5 #include <device/pnp_def.h>
   6 #include <stdint.h>
   7
   8 #include "smscsuperio.h"
   9
  10 #define SMSC_ENTRY_KEY 0x55
  11 #define SMSC_EXIT_KEY 0xAA
  12
  13 /* Enable configuration: pass entry key '0x87' into index port dev. */
  14 static void pnp_enter_conf_state(pnp_devfn_t dev)
  15 {
  16         u16 port = dev >> 8;
  17         outb(SMSC_ENTRY_KEY, port);
  18 }
  19
  20 /* Disable configuration: pass exit key '0xAA' into index port dev. */
  21 static void pnp_exit_conf_state(pnp_devfn_t dev)
  22 {
  23         u16 port = dev >> 8;
  24         outb(SMSC_EXIT_KEY, port);
  25 }
  26
  27 /**
  28  * Enable the specified serial port.
  29  *
  30  * @param dev The device to use.
  31  * @param iobase The I/O base of the serial port (usually 0x3f8/0x2f8).
  32  */
  33 void smscsuperio_enable_serial(pnp_devfn_t dev, u16 iobase)
  34 {
  35         pnp_enter_conf_state(dev);
  36         pnp_set_logical_device(dev);
  37         pnp_set_enable(dev, 0);
  38         pnp_set_iobase(dev, PNP_IDX_IO0, iobase);
  39         switch (iobase) {
  40         case 0x03f8:
  41                 pnp_set_irq(dev, PNP_IDX_IRQ0, 4);
  42                 break;
  43         case 0x02f8:
  44                 pnp_set_irq(dev, PNP_IDX_IRQ0, 3);
  45                 break;
  46         }
  47         pnp_set_enable(dev, 1);
  48         pnp_exit_conf_state(dev);
  49 }