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ARM11: improved reset support 

Teach ARM11 how to use:

 - the new "reset-assert" event
 - vector catch to implement "reset halt"
 - use SRST more like other cores do
 - ... including leaving post-SRST delays up to config scripts

This gives OMAP2420 the ability to reset, and doesn't seem to
cause new iMX31 problems.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
This commit is contained in:
David Brownell 2009-12-14 19:56:36 -08:00
parent 27b13e3377
commit bb77e5d32f
1 changed files with 57 additions and 50 deletions
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107
src/target/arm11.c
View File

@ -352,7 +352,9 @@ static int arm11_poll(struct target *target)
return retval;
target_call_event_callbacks(target,
old_state == TARGET_DEBUG_RUNNING ? TARGET_EVENT_DEBUG_HALTED : TARGET_EVENT_HALTED);
(old_state == TARGET_DEBUG_RUNNING)
? TARGET_EVENT_DEBUG_HALTED
: TARGET_EVENT_HALTED);
}
}
else
@ -749,67 +751,72 @@ static int arm11_step(struct target *target, int current,
static int arm11_assert_reset(struct target *target)
{
int retval;
struct arm11_common *arm11 = target_to_arm11(target);
retval = arm11_check_init(arm11);
if (retval != ERROR_OK)
return retval;
/* optionally catch reset vector */
if (target->reset_halt && !(arm11_vcr & 1))
arm11_sc7_set_vcr(arm11, arm11_vcr | 1);
target->state = TARGET_UNKNOWN;
/* we would very much like to reset into the halted, state,
* but resetting and halting is second best... */
if (target->reset_halt)
{
CHECK_RETVAL(target_halt(target));
/* Issue some kind of warm reset. */
if (target_has_event_action(target, TARGET_EVENT_RESET_ASSERT)) {
target_handle_event(target, TARGET_EVENT_RESET_ASSERT);
} else if (jtag_get_reset_config() & RESET_HAS_SRST) {
/* REVISIT handle "pulls" cases, if there's
* hardware that needs them to work.
*/
jtag_add_reset(0, 1);
} else {
LOG_ERROR("%s: how to reset?", target_name(target));
return ERROR_FAIL;
}
/* registers are now invalid */
register_cache_invalidate(arm11->arm.core_cache);
/* srst is funny. We can not do *anything* else while it's asserted
* and it has unkonwn side effects. Make sure no other code runs
* meanwhile.
*
* Code below assumes srst:
*
* - Causes power-on-reset (but of what parts of the system?). Bug
* in arm11?
*
* - Messes us TAP state without asserting trst.
*
* - There is another bug in the arm11 core. When you generate an access to
* external logic (for example ddr controller via AHB bus) and that block
* is not configured (perhaps it is still held in reset), that transaction
* will never complete. This will hang arm11 core but it will also hang
* JTAG controller. Nothing, short of srst assertion will bring it out of
* this.
*
* Mysteries:
*
* - What should the PC be after an srst reset when starting in the halted
* state?
*/
jtag_add_reset(0, 1);
jtag_add_reset(0, 0);
/* How long do we have to wait? */
jtag_add_sleep(5000);
/* un-mess up TAP state */
jtag_add_tlr();
retval = jtag_execute_queue();
if (retval != ERROR_OK)
{
return retval;
}
target->state = TARGET_RESET;
return ERROR_OK;
}
/*
* - There is another bug in the arm11 core. (iMX31 specific again?)
* When you generate an access to external logic (for example DDR
* controller via AHB bus) and that block is not configured (perhaps
* it is still held in reset), that transaction will never complete.
* This will hang arm11 core but it will also hang JTAG controller.
* Nothing short of srst assertion will bring it out of this.
*/
static int arm11_deassert_reset(struct target *target)
{
struct arm11_common *arm11 = target_to_arm11(target);
int retval;
/* be certain SRST is off */
jtag_add_reset(0, 0);
/* WORKAROUND i.MX31 problems: SRST goofs the TAP, and resets
* at least DSCR. OMAP24xx doesn't show that problem, though
* SRST-only reset seems to be problematic for other reasons.
* (Secure boot sequences being one likelihood!)
*/
jtag_add_tlr();
retval = arm11_poll(target);
if (target->reset_halt) {
if (target->state != TARGET_HALTED) {
LOG_WARNING("%s: ran after reset and before halt ...",
target_name(target));
if ((retval = target_halt(target)) != ERROR_OK)
return retval;
}
}
/* maybe restore vector catch config */
if (target->reset_halt && !(arm11_vcr & 1))
arm11_sc7_set_vcr(arm11, arm11_vcr);
return ERROR_OK;
}