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 ***************************************************************************/
28 #include <jtag/interface.h>
29 #include <jtag/commands.h>
32 * Function bitbang_stableclocks
33 * issues a number of clock cycles while staying in a stable state.
34 * Because the TMS value required to stay in the RESET state is a 1, whereas
35 * the TMS value required to stay in any of the other stable states is a 0,
36 * this function checks the current stable state to decide on the value of TMS
39 static void bitbang_stableclocks(int num_cycles);
42 struct bitbang_interface *bitbang_interface;
44 /* DANGER!!!! clock absolutely *MUST* be 0 in idle or reset won't work!
46 * Set this to 1 and str912 reset halt will fail.
48 * If someone can submit a patch with an explanation it will be greatly
49 * appreciated, but as far as I can tell (ØH) DCLK is generated upon
50 * clk = 0 in TAP_IDLE. Good luck deducing that from the ARM documentation!
51 * The ARM documentation uses the term "DCLK is asserted while in the TAP_IDLE
52 * state". With hardware there is no such thing as *while* in a state. There
53 * are only edges. So clk => 0 is in fact a very subtle state transition that
54 * happens *while* in the TAP_IDLE state. "#&¤"#¤&"#&"#&
56 * For "reset halt" the last thing that happens before srst is asserted
57 * is that the breakpoint is set up. If DCLK is not wiggled one last
58 * time before the reset, then the breakpoint is not set up and
59 * "reset halt" will fail to halt.
62 #define CLOCK_IDLE() 0
65 /* The bitbang driver leaves the TCK 0 when in idle */
66 static void bitbang_end_state(tap_state_t state)
68 if (tap_is_state_stable(state))
69 tap_set_end_state(state);
72 LOG_ERROR("BUG: %i is not a valid end state", state);
77 static void bitbang_state_move(int skip)
80 uint8_t tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
81 int tms_count = tap_get_tms_path_len(tap_get_state(), tap_get_end_state());
83 for (i = skip; i < tms_count; i++)
85 tms = (tms_scan >> i) & 1;
86 bitbang_interface->write(0, tms, 0);
87 bitbang_interface->write(1, tms, 0);
89 bitbang_interface->write(CLOCK_IDLE(), tms, 0);
91 tap_set_state(tap_get_end_state());
96 * Clock a bunch of TMS (or SWDIO) transitions, to change the JTAG
97 * (or SWD) state machine.
99 static int bitbang_execute_tms(struct jtag_command *cmd)
101 unsigned num_bits = cmd->cmd.tms->num_bits;
102 const uint8_t *bits = cmd->cmd.tms->bits;
104 DEBUG_JTAG_IO("TMS: %d bits", num_bits);
107 for (unsigned i = 0; i < num_bits; i++)
109 tms = ((bits[i/8] >> (i % 8)) & 1);
110 bitbang_interface->write(0, tms, 0);
111 bitbang_interface->write(1, tms, 0);
113 bitbang_interface->write(CLOCK_IDLE(), tms, 0);
119 static void bitbang_path_move(struct pathmove_command *cmd)
121 int num_states = cmd->num_states;
128 if (tap_state_transition(tap_get_state(), false) == cmd->path[state_count])
132 else if (tap_state_transition(tap_get_state(), true) == cmd->path[state_count])
138 LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition", tap_state_name(tap_get_state()), tap_state_name(cmd->path[state_count]));
142 bitbang_interface->write(0, tms, 0);
143 bitbang_interface->write(1, tms, 0);
145 tap_set_state(cmd->path[state_count]);
150 bitbang_interface->write(CLOCK_IDLE(), tms, 0);
152 tap_set_end_state(tap_get_state());
155 static void bitbang_runtest(int num_cycles)
159 tap_state_t saved_end_state = tap_get_end_state();
161 /* only do a state_move when we're not already in IDLE */
162 if (tap_get_state() != TAP_IDLE)
164 bitbang_end_state(TAP_IDLE);
165 bitbang_state_move(0);
168 /* execute num_cycles */
169 for (i = 0; i < num_cycles; i++)
171 bitbang_interface->write(0, 0, 0);
172 bitbang_interface->write(1, 0, 0);
174 bitbang_interface->write(CLOCK_IDLE(), 0, 0);
176 /* finish in end_state */
177 bitbang_end_state(saved_end_state);
178 if (tap_get_state() != tap_get_end_state())
179 bitbang_state_move(0);
183 static void bitbang_stableclocks(int num_cycles)
185 int tms = (tap_get_state() == TAP_RESET ? 1 : 0);
188 /* send num_cycles clocks onto the cable */
189 for (i = 0; i < num_cycles; i++)
191 bitbang_interface->write(1, tms, 0);
192 bitbang_interface->write(0, tms, 0);
198 static void bitbang_scan(bool ir_scan, enum scan_type type, uint8_t *buffer, int scan_size)
200 tap_state_t saved_end_state = tap_get_end_state();
203 if (!((!ir_scan && (tap_get_state() == TAP_DRSHIFT)) || (ir_scan && (tap_get_state() == TAP_IRSHIFT))))
206 bitbang_end_state(TAP_IRSHIFT);
208 bitbang_end_state(TAP_DRSHIFT);
210 bitbang_state_move(0);
211 bitbang_end_state(saved_end_state);
214 for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++)
217 int tms = (bit_cnt == scan_size-1) ? 1 : 0;
219 int bytec = bit_cnt/8;
220 int bcval = 1 << (bit_cnt % 8);
222 /* if we're just reading the scan, but don't care about the output
223 * default to outputting 'low', this also makes valgrind traces more readable,
224 * as it removes the dependency on an uninitialised value
227 if ((type != SCAN_IN) && (buffer[bytec] & bcval))
230 bitbang_interface->write(0, tms, tdi);
232 if (type != SCAN_OUT)
233 val = bitbang_interface->read();
235 bitbang_interface->write(1, tms, tdi);
237 if (type != SCAN_OUT)
240 buffer[bytec] |= bcval;
242 buffer[bytec] &= ~bcval;
246 if (tap_get_state() != tap_get_end_state())
248 /* we *KNOW* the above loop transitioned out of
249 * the shift state, so we skip the first state
250 * and move directly to the end state.
252 bitbang_state_move(1);
256 int bitbang_execute_queue(void)
258 struct jtag_command *cmd = jtag_command_queue; /* currently processed command */
264 if (!bitbang_interface)
266 LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
270 /* return ERROR_OK, unless a jtag_read_buffer returns a failed check
271 * that wasn't handled by a caller-provided error handler
275 if (bitbang_interface->blink)
276 bitbang_interface->blink(1);
283 #ifdef _DEBUG_JTAG_IO_
284 LOG_DEBUG("reset trst: %i srst %i", cmd->cmd.reset->trst, cmd->cmd.reset->srst);
286 if ((cmd->cmd.reset->trst == 1) || (cmd->cmd.reset->srst && (jtag_get_reset_config() & RESET_SRST_PULLS_TRST)))
288 tap_set_state(TAP_RESET);
290 bitbang_interface->reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
293 #ifdef _DEBUG_JTAG_IO_
294 LOG_DEBUG("runtest %i cycles, end in %s", cmd->cmd.runtest->num_cycles, tap_state_name(cmd->cmd.runtest->end_state));
296 bitbang_end_state(cmd->cmd.runtest->end_state);
297 bitbang_runtest(cmd->cmd.runtest->num_cycles);
300 case JTAG_STABLECLOCKS:
301 /* this is only allowed while in a stable state. A check for a stable
302 * state was done in jtag_add_clocks()
304 bitbang_stableclocks(cmd->cmd.stableclocks->num_cycles);
308 #ifdef _DEBUG_JTAG_IO_
309 LOG_DEBUG("statemove end in %s", tap_state_name(cmd->cmd.statemove->end_state));
311 bitbang_end_state(cmd->cmd.statemove->end_state);
312 bitbang_state_move(0);
315 #ifdef _DEBUG_JTAG_IO_
316 LOG_DEBUG("pathmove: %i states, end in %s", cmd->cmd.pathmove->num_states,
317 tap_state_name(cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]));
319 bitbang_path_move(cmd->cmd.pathmove);
322 #ifdef _DEBUG_JTAG_IO_
323 LOG_DEBUG("%s scan end in %s", (cmd->cmd.scan->ir_scan) ? "IR" : "DR", tap_state_name(cmd->cmd.scan->end_state));
325 bitbang_end_state(cmd->cmd.scan->end_state);
326 scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
327 type = jtag_scan_type(cmd->cmd.scan);
328 bitbang_scan(cmd->cmd.scan->ir_scan, type, buffer, scan_size);
329 if (jtag_read_buffer(buffer, cmd->cmd.scan) != ERROR_OK)
330 retval = ERROR_JTAG_QUEUE_FAILED;
335 #ifdef _DEBUG_JTAG_IO_
336 LOG_DEBUG("sleep %" PRIi32, cmd->cmd.sleep->us);
338 jtag_sleep(cmd->cmd.sleep->us);
341 retval = bitbang_execute_tms(cmd);
344 LOG_ERROR("BUG: unknown JTAG command type encountered");
349 if (bitbang_interface->blink)
350 bitbang_interface->blink(0);