jtag/ports.c

   1 /*******************************************************/
   2 /* file: ports.c                                       */
   3 /* abstract:  This file contains the routines to       */
   4 /*            output values on the JTAG ports, to read */
   5 /*            the TDO bit, and to read a byte of data  */
   6 /*            from the prom                            */
   7 /*                                                     */
   8 /*******************************************************/
   9 #include "ports.h"
  10
  11 #define JTAG_TDO     0x01   /* Data Out */
  12 #define JTAG_TDO_BAR 0x10
  13
  14 #define JTAG_TDI     0x02   /* Data In */
  15 #define JTAG_TDI_BAR 0x20
  16
  17 #define JTAG_TMS     0x04   /* Mode Select */
  18 #define JTAG_TMS_BAR 0x40
  19
  20 #define JTAG_TCK     0x08   /* Clock */
  21 #define JTAG_TCK_BAR 0x80
  22
  23 static unsigned long dito = 0;
  24 #define DITO 200000
  25
  26 /*******************************************************/
  27 /* Swap bytes on little endian systems                 */
  28
  29 short swap(short word) {
  30
  31 char l,r;
  32
  33    r = word & 0xFF;
  34    l = word >> 8;
  35    word = (r << 8) | (l & 0xFF);
  36
  37    return word;
  38 }
  39
  40 /*******************************************************/
  41 /* Write one bit to selected Jtag bit                  */
  42 /* p is the jtag port TMS, TDI or TCK                  */
  43 /* val contains the bit value one or zero              */
  44
  45 void setPort(short p,short val) {
  46    if (val) {
  47       if      (p == TMS) { jtag |=  JTAG_TMS;
  48                            jtag &= ~JTAG_TMS_BAR; }
  49       else if (p == TDI) { jtag |=  JTAG_TDI;
  50                            jtag &= ~JTAG_TDI_BAR; }
  51       else if (p == TCK) { jtag |=  JTAG_TCK;
  52                            jtag &= ~JTAG_TCK_BAR; }
  53       else return;
  54    } else {
  55       if      (p == TMS) { jtag |=  JTAG_TMS_BAR;
  56                            jtag &= ~JTAG_TMS; }
  57       else if (p == TDI) { jtag |=  JTAG_TDI_BAR;
  58                            jtag &= ~JTAG_TDI; }
  59       else if (p == TCK) { jtag |=  JTAG_TCK_BAR;
  60                            jtag &= ~JTAG_TCK; }
  61       else return;
  62    }
  63    if (jtagAddr) *jtagAddr = swap(jtag);
  64
  65    if ((dito++ % DITO) == 0) {
  66       printf("\7.");
  67       fflush(stdout);
  68    }
  69 }
  70
  71 /*******************************************************/
  72 /* read in a byte of data from the input stream        */
  73
  74 void readByte(unsigned char *data) {
  75
  76     *data = (unsigned char) fgetc(inp);
  77 }
  78
  79 /*******************************************************/
  80 /* read the TDO bit from port                          */
  81
  82 unsigned char readTDOBit() {
  83 unsigned short rback;
  84
  85    if (jtagAddr) rback = swap(*jtagAddr);
  86    if (rback & JTAG_TDO)
  87       return (unsigned char) 1;
  88    return (unsigned char) 0;
  89 }
  90
  91 /*****************************************************************************/
  92 /* Wait at least the specified number of microsec.                           */
  93
  94 void waitTime(long microsec) {
  95    setPort(TCK,0);  /* set the TCK port to low  */
  96    usleep(microsec);
  97 }
  98
  99 /*******************************************************/
 100 /* Pulse the TCK clock                                 */
 101
 102 void pulseClock() {
 103
 104     setPort(TCK,0);  /* set the TCK port to low  */
 105     setPort(TCK,1);  /* set the TCK port to high */
 106 }