pci.c

在dos下读写pci卡

#include <dos.h>
#include <stddef.h>

/*---PCI Functions---*/
#define PCI_BIOS_PRESENT          0x01
#define FIND_PCI_DEVICE           0x02
#define READ_CONFIG_DWORD         0x0a
#define PCI_FUNCTION_ID           0xb1

/*---Return Code ---*/
#define SUCCESSFUL               0x00
#define NOT_SUCCESSFUL           0x01

/*---PCI Configuration Space Registers---*/

#define PCI_CS_VENDOR_ID         0x00
#define PCI_CS_DEVICE_ID         0x02
#define PCI_CS_COMMAND           0x04
#define PCI_CS_STATUS            0x06
#define PCI_CS_REVISION_ID       0x08
#define PCI_CS_CLASS_CODE        0x09
#define PCI_CS_CACHE_LINE_SIZE   0x0c
#define PCI_CS_MASTER_LATENCY    0x0d
#define PCI_CS_HEADER_TYPE       0x0e
#define PCI_CS_BIST              0x0f
#define PCI_CS_BASE_ADDRESS_0    0x10
#define PCI_CS_BASE_ADDRESS_1    0x14
#define PCI_CS_BASE_ADDRESS_2    0x18
#define PCI_CS_BASE_ADDRESS_3    0x1c
#define PCI_CS_BASE_ADDRESS_4    0x20
#define PCI_CS_BASE_ADDRESS_5    0x24
#define PCI_CS_SUBSYSTEM_ID      0x2c
#define PCI_CS_EXPANSION_ROM     0x30
#define PCI_CS_INTERRUPT_LINE    0x3c
#define PCI_CS_INTERRUPT_PIN     0x3d

/*---Define macros to obtain individual bytes from a word register---*/
#define TRUE    1
#define FALSE   0
#define HIGH_BYTE(ax) (ax >> 8)
#define LOW_BYTE(ax) (ax & 0xff)
#define CARRY_FLAG 0x01         /* 80x86 Flags Register Carry Flag bit */

typedef unsigned char byte;     /* byte data type */
typedef unsigned short word;    /* word data type */
typedef unsigned long dword;    /* double word data type */

/* Function Prototypes */
static int read_configuration_area(byte function, byte bus_number,
                                   byte device_and_function,
                                   byte register_number, dword *data);

int find_pci_device(word device_id, word vendor_id, word index,
                    byte *bus_number, byte *device_and_function);

int read_configuration_dword(byte bus_number, byte device_and_function,
                             byte register_number, dword *dword_read);

/* Function source code */
int find_pci_device(word device_id,
                    word vendor_id,
                    word index,
                    byte *bus_number,
                    byte *device_and_function)
{
   int ret_status;
   word ax, bx, flags;

   /* Set registers for PCI BIOS call */
   _CX = device_id;
   _DX = vendor_id;
   _SI = index;
   _AH = PCI_FUNCTION_ID;
   _AL = FIND_PCI_DEVICE;

   /* Call PCI BIOS Int 1Ah */
   geninterrupt(0x1a);

   ax = _AX;
   bx = _BX;
   flags = _FLAGS;

   /* if carry flag set, error has occurred */
   if ((flags & CARRY_FLAG) == 0)
     {
       /* Get Return code from BIOS */
       ret_status = HIGH_BYTE(ax);

       if (ret_status == SUCCESSFUL)
        {
          /* Assign Bus Number, Device & Function if successful */
          if (bus_number != NULL)
            { *bus_number = HIGH_BYTE(bx); }

          if (device_and_function != NULL)
            { *device_and_function = LOW_BYTE(bx); }
        }
     }
    else
     { ret_status = NOT_SUCCESSFUL; }

   return (ret_status);
}

int read_configuration_dword(byte bus_number, byte device_and_function,
                             byte register_number, dword *dword_read)
{
   int ret_status;
   dword data;

   /* Read PCI configuration register data */
   ret_status = read_configuration_area(READ_CONFIG_DWORD, bus_number,
                                        device_and_function,
                                        register_number, &data);
   if (ret_status == SUCCESSFUL)
     { *dword_read = data; }

   return (ret_status);
}

static int read_configuration_area(byte function, byte bus_number,
                                   byte device_and_function,
                                   byte register_number, dword *data)
{
   int ret_status;
   word ax, flags;
   dword ecx;

   /* Load entry registers for PCI BIOS */
   _BH = bus_number;
   _BL = device_and_function;
   _DI = register_number;
   _AH = PCI_FUNCTION_ID;
   _AL = function;

   /* Call PCI BIOS Int 1Ah interface */
   geninterrupt(0x1a);

   ecx = _ECX;
   ax = _AX;
   flags = _FLAGS;

   /* if carry flag Set, error has occurred */
   if ((flags & CARRY_FLAG) == 0)
     {
       /* Get Return code from BIOS */
       ret_status = HIGH_BYTE(ax);

       /* If successful, return data */
       if (ret_status == SUCCESSFUL)
         { *data = ecx; }
     }
    else
     { ret_status = NOT_SUCCESSFUL; }

   return (ret_status);
}