1 /***************************************************************************
2 * Copyright (C) 2005 by Dominic Rath *
3 * Dominic.Rath@gmx.de *
5 * Copyright (C) 2007,2008 Øyvind Harboe *
6 * oyvind.harboe@zylin.com *
8 * This program is free software; you can redistribute it and/or modify *
9 * it under the terms of the GNU General Public License as published by *
10 * the Free Software Foundation; either version 2 of the License, or *
11 * (at your option) any later version. *
13 * This program is distributed in the hope that it will be useful, *
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of *
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
16 * GNU General Public License for more details. *
18 * You should have received a copy of the GNU General Public License *
19 * along with this program; if not, write to the *
20 * Free Software Foundation, Inc., *
21 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
22 ***************************************************************************/
29 /* project specific includes */
33 #include "configuration.h"
42 * Function bitbang_stableclocks
43 * issues a number of clock cycles while staying in a stable state.
44 * Because the TMS value required to stay in the RESET state is a 1, whereas
45 * the TMS value required to stay in any of the other stable states is a 0,
46 * this function checks the current stable state to decide on the value of TMS
49 static void bitbang_stableclocks(int num_cycles);
52 bitbang_interface_t *bitbang_interface;
54 /* DANGER!!!! clock absolutely *MUST* be 0 in idle or reset won't work!
56 * Set this to 1 and str912 reset halt will fail.
58 * If someone can submit a patch with an explanation it will be greatly
59 * appreciated, but as far as I can tell (ØH) DCLK is generated upon
60 * clk=0 in TAP_IDLE. Good luck deducing that from the ARM documentation!
61 * The ARM documentation uses the term "DCLK is asserted while in the TAP_IDLE
62 * state". With hardware there is no such thing as *while* in a state. There
63 * are only edges. So clk => 0 is in fact a very subtle state transition that
64 * happens *while* in the TAP_IDLE state. "#&¤"#¤&"#&"#&
66 * For "reset halt" the last thing that happens before srst is asserted
67 * is that the breakpoint is set up. If DCLK is not wiggled one last
68 * time before the reset, then the breakpoint is not set up and
69 * "reset halt" will fail to halt.
72 #define CLOCK_IDLE() 0
75 /* The bitbang driver leaves the TCK 0 when in idle */
76 static void bitbang_end_state(tap_state_t state)
78 if (tap_is_state_stable(state))
79 tap_set_end_state(state);
82 LOG_ERROR("BUG: %i is not a valid end state", state);
87 static void bitbang_state_move(int skip)
90 u8 tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
92 for (i = skip; i < 7; i++)
94 tms = (tms_scan >> i) & 1;
95 bitbang_interface->write(0, tms, 0);
96 bitbang_interface->write(1, tms, 0);
98 bitbang_interface->write(CLOCK_IDLE(), tms, 0);
100 tap_set_state(tap_get_end_state());
103 static void bitbang_path_move(pathmove_command_t *cmd)
105 int num_states = cmd->num_states;
112 if (tap_state_transition(tap_get_state(), false) == cmd->path[state_count])
116 else if (tap_state_transition(tap_get_state(), true) == cmd->path[state_count])
122 LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition", tap_state_name(tap_get_state()), tap_state_name(cmd->path[state_count]));
126 bitbang_interface->write(0, tms, 0);
127 bitbang_interface->write(1, tms, 0);
129 tap_set_state(cmd->path[state_count]);
134 bitbang_interface->write(CLOCK_IDLE(), tms, 0);
136 tap_set_end_state(tap_get_state());
139 static void bitbang_runtest(int num_cycles)
143 tap_state_t saved_end_state = tap_get_end_state();
145 /* only do a state_move when we're not already in IDLE */
146 if (tap_get_state() != TAP_IDLE)
148 bitbang_end_state(TAP_IDLE);
149 bitbang_state_move(0);
152 /* execute num_cycles */
153 for (i = 0; i < num_cycles; i++)
155 bitbang_interface->write(0, 0, 0);
156 bitbang_interface->write(1, 0, 0);
158 bitbang_interface->write(CLOCK_IDLE(), 0, 0);
160 /* finish in end_state */
161 bitbang_end_state(saved_end_state);
162 if (tap_get_state() != tap_get_end_state())
163 bitbang_state_move(0);
167 static void bitbang_stableclocks(int num_cycles)
169 int tms = (tap_get_state() == TAP_RESET ? 1 : 0);
172 /* send num_cycles clocks onto the cable */
173 for (i = 0; i < num_cycles; i++)
175 bitbang_interface->write(1, tms, 0);
176 bitbang_interface->write(0, tms, 0);
182 static void bitbang_scan(int ir_scan, enum scan_type type, u8 *buffer, int scan_size)
184 tap_state_t saved_end_state = tap_get_end_state();
187 if (!((!ir_scan && (tap_get_state() == TAP_DRSHIFT)) || (ir_scan && (tap_get_state() == TAP_IRSHIFT))))
190 bitbang_end_state(TAP_IRSHIFT);
192 bitbang_end_state(TAP_DRSHIFT);
194 bitbang_state_move(0);
195 bitbang_end_state(saved_end_state);
198 for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++)
201 int tms=(bit_cnt==scan_size-1) ? 1 : 0;
204 int bcval=1<<(bit_cnt % 8);
206 /* if we're just reading the scan, but don't care about the output
207 * default to outputting 'low', this also makes valgrind traces more readable,
208 * as it removes the dependency on an uninitialised value
211 if ((type != SCAN_IN) && (buffer[bytec] & bcval))
214 bitbang_interface->write(0, tms, tdi);
217 val=bitbang_interface->read();
219 bitbang_interface->write(1, tms, tdi);
221 if (type != SCAN_OUT)
224 buffer[bytec] |= bcval;
226 buffer[bytec] &= ~bcval;
230 if (tap_get_state() != tap_get_end_state())
232 /* we *KNOW* the above loop transitioned out of
233 * the shift state, so we skip the first state
234 * and move directly to the end state.
236 bitbang_state_move(1);
240 int bitbang_execute_queue(void)
242 jtag_command_t *cmd = jtag_command_queue; /* currently processed command */
248 if (!bitbang_interface)
250 LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
254 /* return ERROR_OK, unless a jtag_read_buffer returns a failed check
255 * that wasn't handled by a caller-provided error handler
259 if(bitbang_interface->blink)
260 bitbang_interface->blink(1);
267 #ifdef _DEBUG_JTAG_IO_
268 LOG_DEBUG("end_state: %s", tap_state_name(cmd->cmd.end_state->end_state) );
270 if (cmd->cmd.end_state->end_state != TAP_INVALID)
271 bitbang_end_state(cmd->cmd.end_state->end_state);
274 #ifdef _DEBUG_JTAG_IO_
275 LOG_DEBUG("reset trst: %i srst %i", cmd->cmd.reset->trst, cmd->cmd.reset->srst);
277 if ((cmd->cmd.reset->trst == 1) || (cmd->cmd.reset->srst && (jtag_reset_config & RESET_SRST_PULLS_TRST)))
279 tap_set_state(TAP_RESET);
281 bitbang_interface->reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
284 #ifdef _DEBUG_JTAG_IO_
285 LOG_DEBUG("runtest %i cycles, end in %s", cmd->cmd.runtest->num_cycles, tap_state_name(cmd->cmd.runtest->end_state) );
287 if (cmd->cmd.runtest->end_state != TAP_INVALID)
288 bitbang_end_state(cmd->cmd.runtest->end_state);
289 bitbang_runtest(cmd->cmd.runtest->num_cycles);
292 case JTAG_STABLECLOCKS:
293 /* this is only allowed while in a stable state. A check for a stable
294 * state was done in jtag_add_clocks()
296 bitbang_stableclocks(cmd->cmd.stableclocks->num_cycles);
300 #ifdef _DEBUG_JTAG_IO_
301 LOG_DEBUG("statemove end in %s", tap_state_name(cmd->cmd.statemove->end_state));
303 if (cmd->cmd.statemove->end_state != TAP_INVALID)
304 bitbang_end_state(cmd->cmd.statemove->end_state);
305 bitbang_state_move(0);
308 #ifdef _DEBUG_JTAG_IO_
309 LOG_DEBUG("pathmove: %i states, end in %s", cmd->cmd.pathmove->num_states,
310 tap_state_name(cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]));
312 bitbang_path_move(cmd->cmd.pathmove);
315 #ifdef _DEBUG_JTAG_IO_
316 LOG_DEBUG("%s scan end in %s", (cmd->cmd.scan->ir_scan) ? "IR" : "DR", tap_state_name(cmd->cmd.scan->end_state) );
318 if (cmd->cmd.scan->end_state != TAP_INVALID)
319 bitbang_end_state(cmd->cmd.scan->end_state);
320 scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
321 type = jtag_scan_type(cmd->cmd.scan);
322 bitbang_scan(cmd->cmd.scan->ir_scan, type, buffer, scan_size);
323 if (jtag_read_buffer(buffer, cmd->cmd.scan) != ERROR_OK)
324 retval = ERROR_JTAG_QUEUE_FAILED;
329 #ifdef _DEBUG_JTAG_IO_
330 LOG_DEBUG("sleep %i", cmd->cmd.sleep->us);
332 jtag_sleep(cmd->cmd.sleep->us);
335 LOG_ERROR("BUG: unknown JTAG command type encountered");
340 if(bitbang_interface->blink)
341 bitbang_interface->blink(0);