+ struct jtag_tap *tap;
+ tap = ejtag_info->tap;
+ assert(tap != NULL);
+
+ struct scan_field field;
+
+ field.num_bits = 8;
+ field.out_value = &data;
+ field.in_value = NULL;
+
+ jtag_add_dr_scan(tap, 1, &field, TAP_IDLE);
+}
+
+/* Set (to enable) or clear (to disable stepping) the SSt bit (bit 8) in Cp0 Debug reg (reg 23, sel 0) */
+int mips_ejtag_config_step(struct mips_ejtag *ejtag_info, int enable_step)
+{
+ int code_len = enable_step ? 6 : 7;
+
+ uint32_t *code = malloc(code_len * sizeof(uint32_t));
+ if (code == NULL) {
+ LOG_ERROR("Out of memory");
+ return ERROR_FAIL;
+ }
+ uint32_t *code_p = code;
+
+ *code_p++ = MIPS32_MTC0(1, 31, 0); /* move $1 to COP0 DeSave */
+ *code_p++ = MIPS32_MFC0(1, 23, 0), /* move COP0 Debug to $1 */
+ *code_p++ = MIPS32_ORI(1, 1, 0x0100); /* set SSt bit in debug reg */
+ if (!enable_step)
+ *code_p++ = MIPS32_XORI(1, 1, 0x0100); /* clear SSt bit in debug reg */
+
+ *code_p++ = MIPS32_MTC0(1, 23, 0); /* move $1 to COP0 Debug */
+ *code_p++ = MIPS32_B(NEG16((code_len - 1))); /* jump to start */
+ *code_p = MIPS32_MFC0(1, 31, 0); /* move COP0 DeSave to $1 */
+
+ int retval = mips32_pracc_exec(ejtag_info, code_len, code, 0, NULL, 0, NULL, 1);
+
+ free(code);
+ return retval;