jtag.c

   1 /*
   2  * jtag.c - basic jtag stuff (good excercise!)
   3  *
   4  * build: gcc -Wall jtag.c -o jtag
   5  * author: hackbard@hackdaworld.org
   6  *
   7  */
   8
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <unistd.h>
  12 #include <sys/io.h>
  13 #include <string.h>
  14
  15 // variables
  16
  17 #define u16 unsigned short
  18 #define u8 unsigned char
  19 #define u32 unsigned int
  20
  21 // max devices and ir chain len
  22 #define MAXDEV 64
  23 #define MAXIRLEN 32
  24
  25 typedef struct s_jtdrv {
  26         unsigned long ppaddr;
  27         //int *init(t_jtag *jtag);
  28 } t_jtdrv;
  29
  30 typedef struct s_part {
  31         int irlen;
  32         u32 idcode;
  33 } t_part;
  34
  35 typedef struct s_jtag {
  36         int nod;
  37         int tot_ir_len;
  38         t_part part[MAXDEV];
  39 } t_jtag;
  40
  41 // only parallel III cable by now
  42
  43 #define TDI 0x01
  44 #define TMS 0x04
  45 #define TCK 0x02
  46 #define TDO 0x10
  47
  48 // parport functions
  49
  50 int parport_init(unsigned long ppaddr) {
  51
  52         if(ioperm(ppaddr,1,1)||ioperm(ppaddr+1,1,1)) {
  53                 perror("parport init");
  54                 return -1;
  55         }
  56
  57         return 0;
  58
  59 }
  60
  61 int parport_out(u8 data) {
  62
  63         outb(data,0x378);
  64
  65         return 0;
  66
  67 }
  68
  69 int parport_in(u8 *data) {
  70
  71         *data=inb(0x379);
  72
  73         return 0;
  74
  75 }
  76
  77 // jtag low level functions
  78
  79 u8 jtag_clock(u8 tms,u8 tdi) {
  80
  81         u8 in;
  82         u8 out;
  83         u8 tdo;
  84
  85         out=0;
  86         if(tms) out|=TMS;
  87         if(tdi) out|=TDI;
  88         parport_out(out);
  89
  90         parport_in(&in);
  91
  92         tdo=in&TDO?1:0;
  93
  94         // clock cycle
  95         parport_out(out|TCK);
  96         parport_out(out);
  97
  98         return tdo;
  99
 100 }
 101
 102 // jtag mid level functions
 103
 104 int jtag_reset() {
 105
 106         // 5 times TMS
 107         jtag_clock(1,0);
 108         jtag_clock(1,0);
 109         jtag_clock(1,0);
 110         jtag_clock(1,0);
 111         jtag_clock(1,0);
 112
 113         // go to idle mode
 114         jtag_clock(0,0);
 115
 116         return 0;
 117 }
 118
 119 int jtag_enter_shift_ir() {
 120
 121         jtag_clock(1,0);
 122         jtag_clock(1,0);
 123         jtag_clock(0,0);
 124         jtag_clock(0,0);
 125
 126         return 0;
 127
 128 }
 129
 130 int jtag_leave_shift_ir() {
 131
 132         jtag_clock(1,0);
 133         jtag_clock(1,0);
 134         jtag_clock(0,0);
 135
 136         return 0;
 137
 138 }
 139
 140 int jtag_enter_shift_dr() {
 141
 142         jtag_clock(1,0);
 143         jtag_clock(0,0);
 144         jtag_clock(0,0);
 145
 146         return 0;
 147
 148 }
 149
 150 int jtag_leave_shift_dr() {
 151
 152         jtag_clock(1,0);
 153         jtag_clock(1,0);
 154         jtag_clock(0,0);
 155
 156         return 0;
 157
 158 }
 159
 160 int jtag_read_data(u8 *p,int bitlen) {
 161
 162         u8 in;
 163         int count;
 164
 165         memset(p,0,bitlen+7/8);
 166         count=0;
 167
 168         printf("  <- ");
 169         while(bitlen) {
 170                 in=jtag_clock(0,0);
 171                 p[count/8]|=((in&1)<<(count%8));
 172                 printf("%d",p[count/8]&(1<<(count%8))?1:0);
 173                 count+=1;
 174                 bitlen-=1;
 175         }
 176         printf("\n");
 177
 178         return 0;
 179
 180 }
 181
 182 int jtag_write_data(u8 *p,int bitlen) {
 183
 184         int count;
 185
 186         count=0;
 187
 188         printf("  -> ");
 189         while(bitlen) {
 190                 jtag_clock(0,p[count/8]&(1<<(count%8))?1:0);
 191                 printf("%d",p[count/8]&(1<<(count%8))?1:0);
 192                 bitlen-=1;
 193                 count+=1;
 194         }
 195         printf("\n");
 196
 197         return 0;
 198
 199 }
 200
 201 int jtag_chain_init(t_jtag *jtag) {
 202
 203         int i;
 204         u8 tdo;
 205
 206         jtag_enter_shift_ir();
 207         for(i=0;i<MAXIRLEN*MAXDEV;i++) jtag_clock(0,0);
 208         for(i=0;i<MAXIRLEN*MAXDEV;i++) {
 209                 tdo=jtag_clock(0,1);
 210                 if(tdo)
 211                         break;
 212         }
 213         printf("ir len: %d\n",i);
 214         jtag->tot_ir_len=i;
 215         jtag_leave_shift_ir();
 216
 217         jtag_enter_shift_dr();
 218         for(i=0;i<MAXIRLEN*MAXDEV;i++) jtag_clock(0,0);
 219         for(i=0;i<MAXIRLEN*MAXDEV;i++)
 220                 if(jtag_clock(0,1))
 221                          break;
 222         printf("number of devices: %d\n",i);
 223         jtag->nod=i;
 224         jtag_leave_shift_dr();
 225
 226         jtag_reset();
 227         jtag_enter_shift_dr();
 228         for(i=1;i<=jtag->nod;i++) {
 229                 jtag_read_data((u8 *)&(jtag->part[jtag->nod-i].idcode),32);
 230                 printf("idcode of part %d: %x\n",i,jtag->part[jtag->nod-i].idcode);
 231         }
 232         jtag_leave_shift_dr();
 233
 234         return i;
 235
 236 }
 237
 238 int jtag_set_ir(char *s,int bitlen) {
 239
 240         u8 ir[MAXDEV*MAXIRLEN/8];
 241         int count;
 242
 243         if(bitlen>=MAXDEV*MAXIRLEN) {
 244                 printf("instruction register too big!\n");
 245                 return -1;
 246         }
 247
 248         memset(ir,0,MAXDEV*MAXIRLEN/8*sizeof(u8));
 249         count=0;
 250
 251         printf("set ir: ");
 252         while(bitlen) {
 253                 if(s[count]=='1')
 254                         ir[count/8]|=(1<<(count%8));
 255                 printf("%d",ir[count/8]&(1<<(count%8))?1:0);
 256                 count+=1;
 257                 bitlen-=1;
 258         }
 259         printf("\n");
 260
 261         jtag_enter_shift_ir();
 262         jtag_write_data(ir,count);
 263         jtag_leave_shift_ir();
 264
 265         return 0;
 266
 267 }
 268
 269 int main(int argc,char **argv) {
 270
 271         t_jtag jtag;
 272         u8 io[256];
 273
 274         memset(&jtag,0,sizeof(t_jtag));
 275
 276         printf("parport init ...\n");
 277         parport_init(0x378);
 278         printf("done\n\n");
 279
 280         printf("reset test logic ...\n");
 281         jtag_reset();
 282         printf("done\n\n");
 283
 284         printf("jtag chain init ...\n");
 285         jtag_chain_init(&jtag);
 286         printf("done\n\n");
 287
 288         printf("testing some instructions ...\n\n");
 289         jtag_set_ir("000001000001",12);
 290         jtag_enter_shift_dr();
 291         jtag_read_data(io,64);
 292         jtag_leave_shift_dr();
 293
 294         return 0;
 295
 296 }
 297