GIO Driver edtinit() Entry Point

The pfxedtinit() entry point is called only in response to a VECTOR line. However, a VECTOR line need not contain a probe or exprobe test of the hardware.

The driver should not assume that its hardware exists; instead it should use the badaddr() kernel function to test the addresses passed in the edt_t object to make sure they are usable (see "Testing Device Physical Addresses").

Example 18-1 displays a skeleton version of the pfxedtinit() entry point of a hypothetical GIO device driver. This example uses GIO-specific functions that are described in a following section, "GIO-Specific Kernel Functions".

Example 18-1 : GIO Driver edtinit() Entry Point

#include <sys/edt.h>
void
hypoth_edtinit(register struct edt *e)
{
   int slot, val;
   /* Check to see if the device is present */
   if(badaddr_val(e->e_base, sizeof(int), &val) ||
         (val && GBD_MASK) != GBD_BOARD_ID) {
      if (showconfig)
         cmn_err (CE_CONT,
            "gbdedtinit: board not installed.");
         return;
   }
   /* figure out slot from base on VECTOR line in 
   /* system file*/
   if(e->e_base == (caddr_t)0xBf400000)
      slot = GIO_SLOT_0;
   else if(e->e_base == (caddr_t)0xBF600000)
      slot = GIO_SLOT_1;
   else {
      cmn_err (CE_NOTE,
      "ERROR from edtinit: Bad base address %x\n",e->e_base);
      return;
   }
#ifdef IP20   /* For Indigo R4000, set up board as a
                 realtime bus master */
   setgioconfig(slot,GIO64_ARB_EXP0_RT|GIO64_ARB_EXP0_MST);
#endif
#ifdef (IP22|IP26)   /* For Indy, Indigo2, set up board as a
                        pipelined realtime bus master  */
   setgioconfig(slot,GIO64_ARB_EXP0_RT|GIO64_ARB_EXP0_PIPED);
#endif
   /* Save the device addresses, because
    * they won't be available later.
    */
   gbd_device[slot == GIO_SLOT_0 ? 0 : 1] =
            (struct gbd_device *)e->e_base;
   gbd_memory[slot == GIO_SLOT_0 ? 0 : 1] =
            (char *)e->e_base2;
              /* Where "unit_#" is any parameter passed to
              /* the interrupt handler (gbdintr) */
   setgiovector(GIO_INTERRUPT_1,slot,gbdintr,unit_#);
}