arch/alpha/kernel/ns87312.c

   1 /*
   2  *      linux/arch/alpha/kernel/ns87312.c
   3  */
   4
   5 #include <linux/init.h>
   6 #include <asm/io.h>
   7 #include "proto.h"
   8
   9
  10 /*
  11  * The SRM console *disables* the IDE interface, this code ensures it's
  12  * enabled.
  13  *
  14  * This code bangs on a control register of the 87312 Super I/O chip
  15  * that implements parallel port/serial ports/IDE/FDI.  Depending on
  16  * the motherboard, the Super I/O chip can be configured through a
  17  * pair of registers that are located either at I/O ports 0x26e/0x26f
  18  * or 0x398/0x399.  Unfortunately, autodetecting which base address is
  19  * in use works only once (right after a reset).  The Super I/O chip
  20  * has the additional quirk that configuration register data must be
  21  * written twice (I believe this is a safety feature to prevent
  22  * accidental modification---fun, isn't it?).
  23  */
  24
  25 void __init
  26 ns87312_enable_ide(long ide_base)
  27 {
  28         int data;
  29         unsigned long flags;
  30
  31         local_irq_save(flags);
  32         outb(0, ide_base);              /* set the index register for reg #0 */
  33         data = inb(ide_base+1);         /* read the current contents */
  34         outb(0, ide_base);              /* set the index register for reg #0 */
  35         outb(data | 0x40, ide_base+1);  /* turn on IDE */
  36         outb(data | 0x40, ide_base+1);  /* turn on IDE, really! */
  37         local_irq_restore(flags);
  38 }