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 ***************************************************************************/
31 * Function bitbang_stableclocks
32 * issues a number of clock cycles while staying in a stable state.
33 * Because the TMS value required to stay in the RESET state is a 1, whereas
34 * the TMS value required to stay in any of the other stable states is a 0,
35 * this function checks the current stable state to decide on the value of TMS
38 static void bitbang_stableclocks(int num_cycles);
41 bitbang_interface_t *bitbang_interface;
43 /* DANGER!!!! clock absolutely *MUST* be 0 in idle or reset won't work!
45 * Set this to 1 and str912 reset halt will fail.
47 * If someone can submit a patch with an explanation it will be greatly
48 * appreciated, but as far as I can tell (ØH) DCLK is generated upon
49 * clk=0 in TAP_IDLE. Good luck deducing that from the ARM documentation!
50 * The ARM documentation uses the term "DCLK is asserted while in the TAP_IDLE
51 * state". With hardware there is no such thing as *while* in a state. There
52 * are only edges. So clk => 0 is in fact a very subtle state transition that
53 * happens *while* in the TAP_IDLE state. "#&¤"#¤&"#&"#&
55 * For "reset halt" the last thing that happens before srst is asserted
56 * is that the breakpoint is set up. If DCLK is not wiggled one last
57 * time before the reset, then the breakpoint is not set up and
58 * "reset halt" will fail to halt.
61 #define CLOCK_IDLE() 0
64 /* The bitbang driver leaves the TCK 0 when in idle */
65 static void bitbang_end_state(tap_state_t state)
67 if (tap_is_state_stable(state))
68 tap_set_end_state(state);
71 LOG_ERROR("BUG: %i is not a valid end state", state);
76 static void bitbang_state_move(int skip)
79 u8 tms_scan = tap_get_tms_path(tap_get_state(), tap_get_end_state());
80 int tms_count = tap_get_tms_path_len(tap_get_state(), tap_get_end_state());
82 for (i = skip; i < tms_count; i++)
84 tms = (tms_scan >> i) & 1;
85 bitbang_interface->write(0, tms, 0);
86 bitbang_interface->write(1, tms, 0);
88 bitbang_interface->write(CLOCK_IDLE(), tms, 0);
90 tap_set_state(tap_get_end_state());
93 static void bitbang_path_move(pathmove_command_t *cmd)
95 int num_states = cmd->num_states;
102 if (tap_state_transition(tap_get_state(), false) == cmd->path[state_count])
106 else if (tap_state_transition(tap_get_state(), true) == cmd->path[state_count])
112 LOG_ERROR("BUG: %s -> %s isn't a valid TAP transition", tap_state_name(tap_get_state()), tap_state_name(cmd->path[state_count]));
116 bitbang_interface->write(0, tms, 0);
117 bitbang_interface->write(1, tms, 0);
119 tap_set_state(cmd->path[state_count]);
124 bitbang_interface->write(CLOCK_IDLE(), tms, 0);
126 tap_set_end_state(tap_get_state());
129 static void bitbang_runtest(int num_cycles)
133 tap_state_t saved_end_state = tap_get_end_state();
135 /* only do a state_move when we're not already in IDLE */
136 if (tap_get_state() != TAP_IDLE)
138 bitbang_end_state(TAP_IDLE);
139 bitbang_state_move(0);
142 /* execute num_cycles */
143 for (i = 0; i < num_cycles; i++)
145 bitbang_interface->write(0, 0, 0);
146 bitbang_interface->write(1, 0, 0);
148 bitbang_interface->write(CLOCK_IDLE(), 0, 0);
150 /* finish in end_state */
151 bitbang_end_state(saved_end_state);
152 if (tap_get_state() != tap_get_end_state())
153 bitbang_state_move(0);
157 static void bitbang_stableclocks(int num_cycles)
159 int tms = (tap_get_state() == TAP_RESET ? 1 : 0);
162 /* send num_cycles clocks onto the cable */
163 for (i = 0; i < num_cycles; i++)
165 bitbang_interface->write(1, tms, 0);
166 bitbang_interface->write(0, tms, 0);
172 static void bitbang_scan(bool ir_scan, enum scan_type type, u8 *buffer, int scan_size)
174 tap_state_t saved_end_state = tap_get_end_state();
177 if (!((!ir_scan && (tap_get_state() == TAP_DRSHIFT)) || (ir_scan && (tap_get_state() == TAP_IRSHIFT))))
180 bitbang_end_state(TAP_IRSHIFT);
182 bitbang_end_state(TAP_DRSHIFT);
184 bitbang_state_move(0);
185 bitbang_end_state(saved_end_state);
188 for (bit_cnt = 0; bit_cnt < scan_size; bit_cnt++)
191 int tms=(bit_cnt==scan_size-1) ? 1 : 0;
194 int bcval=1<<(bit_cnt % 8);
196 /* if we're just reading the scan, but don't care about the output
197 * default to outputting 'low', this also makes valgrind traces more readable,
198 * as it removes the dependency on an uninitialised value
201 if ((type != SCAN_IN) && (buffer[bytec] & bcval))
204 bitbang_interface->write(0, tms, tdi);
207 val=bitbang_interface->read();
209 bitbang_interface->write(1, tms, tdi);
211 if (type != SCAN_OUT)
214 buffer[bytec] |= bcval;
216 buffer[bytec] &= ~bcval;
220 if (tap_get_state() != tap_get_end_state())
222 /* we *KNOW* the above loop transitioned out of
223 * the shift state, so we skip the first state
224 * and move directly to the end state.
226 bitbang_state_move(1);
230 int bitbang_execute_queue(void)
232 jtag_command_t *cmd = jtag_command_queue; /* currently processed command */
238 if (!bitbang_interface)
240 LOG_ERROR("BUG: Bitbang interface called, but not yet initialized");
244 /* return ERROR_OK, unless a jtag_read_buffer returns a failed check
245 * that wasn't handled by a caller-provided error handler
249 if(bitbang_interface->blink)
250 bitbang_interface->blink(1);
257 #ifdef _DEBUG_JTAG_IO_
258 LOG_DEBUG("reset trst: %i srst %i", cmd->cmd.reset->trst, cmd->cmd.reset->srst);
260 if ((cmd->cmd.reset->trst == 1) || (cmd->cmd.reset->srst && (jtag_reset_config & RESET_SRST_PULLS_TRST)))
262 tap_set_state(TAP_RESET);
264 bitbang_interface->reset(cmd->cmd.reset->trst, cmd->cmd.reset->srst);
267 #ifdef _DEBUG_JTAG_IO_
268 LOG_DEBUG("runtest %i cycles, end in %s", cmd->cmd.runtest->num_cycles, tap_state_name(cmd->cmd.runtest->end_state) );
270 if (cmd->cmd.runtest->end_state != TAP_INVALID)
271 bitbang_end_state(cmd->cmd.runtest->end_state);
272 bitbang_runtest(cmd->cmd.runtest->num_cycles);
275 case JTAG_STABLECLOCKS:
276 /* this is only allowed while in a stable state. A check for a stable
277 * state was done in jtag_add_clocks()
279 bitbang_stableclocks(cmd->cmd.stableclocks->num_cycles);
283 #ifdef _DEBUG_JTAG_IO_
284 LOG_DEBUG("statemove end in %s", tap_state_name(cmd->cmd.statemove->end_state));
286 if (cmd->cmd.statemove->end_state != TAP_INVALID)
287 bitbang_end_state(cmd->cmd.statemove->end_state);
288 bitbang_state_move(0);
291 #ifdef _DEBUG_JTAG_IO_
292 LOG_DEBUG("pathmove: %i states, end in %s", cmd->cmd.pathmove->num_states,
293 tap_state_name(cmd->cmd.pathmove->path[cmd->cmd.pathmove->num_states - 1]));
295 bitbang_path_move(cmd->cmd.pathmove);
298 #ifdef _DEBUG_JTAG_IO_
299 LOG_DEBUG("%s scan end in %s", (cmd->cmd.scan->ir_scan) ? "IR" : "DR", tap_state_name(cmd->cmd.scan->end_state) );
301 if (cmd->cmd.scan->end_state != TAP_INVALID)
302 bitbang_end_state(cmd->cmd.scan->end_state);
303 scan_size = jtag_build_buffer(cmd->cmd.scan, &buffer);
304 type = jtag_scan_type(cmd->cmd.scan);
305 bitbang_scan(cmd->cmd.scan->ir_scan, type, buffer, scan_size);
306 if (jtag_read_buffer(buffer, cmd->cmd.scan) != ERROR_OK)
307 retval = ERROR_JTAG_QUEUE_FAILED;
312 #ifdef _DEBUG_JTAG_IO_
313 LOG_DEBUG("sleep %i", cmd->cmd.sleep->us);
315 jtag_sleep(cmd->cmd.sleep->us);
318 LOG_ERROR("BUG: unknown JTAG command type encountered");
323 if(bitbang_interface->blink)
324 bitbang_interface->blink(0);