Initialization Sketch

Initialization Sketch

The code in Example 17-1 represents an outline of the pfxedtinit() entry point for a hypothetical EISA device, showing the allocation of a PIO map, an IRQ, and a DMA channel. The driver supports as many as four identical devices. It keeps information about them in an array of structures, einfo. Each entry to pfxedtinit() initializes one element of this array, as indexed by the ctlr value from the VECTOR statement.

An important point to note in this example is that most of the arguments to pio_map_alloc() can simply be passed as the values from the edt_t received by the entry point.

Example 17-1 : Sketch of EISA Initialization

#include <sys/types.h>
#include <sys/edt.h>
#include <sys/pio.h>
#include <sys/eisa.h>
#include <sys/cmn_err.h>
#define MAX_DEVICE 4
/* Array of info structures about each device. A device
** that does not initialize OK ought to be marked, but
** no such logic is shown.
*/
struct edrv_info {
   caddr_t e_addr[NBASE];     /* pio mapped addr per space */
   int     e_dmachan;         /* dma chan in use */
} einfo[MAX_DEVICE];

#define CARD_ID         0x0163b30a   /* mfr. ID */
#define IRQ_MASK        0x0018       /* acceptable IRQs */
#define DMACHAN_MASK    0x7a         /* acceptable chans */
edrv_edtinit(edt_t *e)
{
   int iospace;         /* index over iospace array */
   int eirq;            /* allocated IRQ # */
   int edma_chan;       /* allocated chan # */
   struct edrv_info *einf; /* -> einfo[n] */
   piomap_t *pmap;

   if (e->e_ctlr < MAX_DEVICE)
      einf = &einfo[e->e_ctlr];
   else
   { /* unknown device, nowhere to put info */
      cmn_err(CE_WARN,"devno too large:%d",e->e_ctlr);
      return;
   }

/* for each nonempty iospace parameter,
** set up a PIO map and save the kv address.
*/
   for (iospace = 0; iospace < NBASE; iospace++) {
      if (!e->e_space[iospace].ios_iopaddr)
         einf->e_addr[iospace] = 0; /* note no addr */
      pmap = pio_mapalloc( /* make a PIO map */
            e->e_bus_type,   /* pass bus type given */
            e->e_adap, /* pass adapter # given */
            &e->e_space[iospace], /* given iospace too */
            PIOMAP_FIXED, /* always fixed for EISA */
            "edrv");
      einf->e_addr[iospace] = pio_mapaddr(pmap,
            e->e_space[iospace].ios_iopaddr);
   }
/* Set up an edge-triggered IRQ for this device.
** Associate it with our interrupt entry point.
** There is no need to remember the assigned IRQ.
*/
   eirq = eisa_ivec_alloc(e->e_adap,IRQ_MASK,EISA_EDGE_IRQ);
   if (eirq < 0) {
      cmn_err(CE_WARN,
         "edrv: ctlr %d could not allocate IRQ\n",
         e->e_ctlr);
      /* should mark einfo unusable */
      return;
   }
   eisa_ivec_set(e->e_adap, eirq, edrv_intr, e->e_ctlr);
/* Allocate a DMA Channel for this device and note
** the number in the device info array.
*/
   edma_chan = eisa_dmachan_alloc(e->e_adap,DMACHAN_MASK);
   if (edma_chan < 0) {
      cmn_err(CE_WARN,
            "edrv: ctlr %d could not allocate DMA Chan\n",
            e->e_ctlr);
      /* should mark einfo unusable */
      return;
   }
   einf->e_dmachan = edma_chan;
}