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Simplify interrupt and RTOS timer tick handlers

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RTOS Timer tick handler is now the same as any other ISR.

This causes a few subtle behaviour changes that seem OK but are worth noting:

* RTOS tick handler sdk__xt_timer_int() is now called from one stack
  frame deeper (inside _xt_isr_handler()), whereas before it was called
  from the level above in UserHandleInterrupt. I can't see any way that
  the extra ~40 bytes of stack use here hurt, though.

* sdk__xt_timer_int() was previous called after all other interrupts
  flagged in the handler, now it's called before the TIMER FRC1 & FRC2
  handlers. The tick handler doesn't appear to do anything particularly
  timing intensive, though.

* GPIO interrupt (value 3) is now lower priority than the SPI
  interrupt (value 2), whereas before it would have been called before
  SPI if both interrupts triggered at once.
This commit is contained in:
Angus Gratton 2015-09-24 10:17:07 +10:00
parent ed8470631f
commit 89c481c606
4 changed files with 31 additions and 68 deletions
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39
core/exception_vectors.S
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@ -469,7 +469,6 @@ CallNMIExceptionHandler:
* LoadStoreCause. */
.literal_position
.balign 4
UserExceptionHandler:
.type UserExceptionHandler, @function
@ -490,46 +489,28 @@ UserExceptionHandler:
wsr a0, ps
rsync
rsr a2, exccause
beqi a2, CAUSE_LVL1INT, UserHandleInterrupt
/* Any UserException cause other than level 1 interrupt should panic */
UserFailOtherExceptionCause:
break 1, 1
call0 sdk_user_fatal_exception_handler
UserHandleInterrupt:
/* Any UserException cause other than a level 1 interrupt is fatal */
bnei a2, CAUSE_LVL1INT, .UserFailOtherExceptionCause
.UserHandleInterrupt:
rsil a0, 1
rsr a2, intenable
rsr a3, interrupt
movi a4, 0x3fff
and a2, a2, a3
and a2, a2, a4 # a2 = 0x3FFF & INTENABLE & INTERRUPT
UserHandleTimer:
movi a3, 0xffbf
and a3, a2, a3 # a3 = a2 with bit 6 cleared
bnez a3, UserTimerDone # If any non-timer interrupt bits set
movi a3, 0x40
sub a12, a2, a3 # a12 = a2 - 0x40 -- Will be zero if bit 6 set
call0 sdk__xt_timer_int # tick timer interrupt
mov a2, a12 # restore a2 from a12, ie zero
beqz a2, UserIntDone
UserTimerDone:
and a2, a2, a4 # a2 = 0x3FFF & INTENABLE & INTERRUPT
call0 _xt_isr_handler
bnez a2, UserHandleTimer
UserIntDone:
beqz a2, UserIntExit
/* FIXME: this code will never be reached */
j sdk__xt_int_exit # once finished, jumps to _xt_user_exit via stack
.literal_position
.UserFailOtherExceptionCause:
break 1, 1
call0 sdk_user_fatal_exception_handler
UserIntExit:
call0 sdk__xt_int_exit # jumps to _xt_user_exit. Never returns here
.section .text
/* _xt_user_exit is used to exit interrupt context. */
/* TODO: Find a better place for this to live. */
/* _xt_user_exit is pushed onto the stack as part of the user exception handler,
restores same set registers which were saved there and returns from exception */
_xt_user_exit:
.global _xt_user_exit
.type _xt_user_exit, @function
l32i a0, sp, 0x8
wsr a0, ps
l32i a0, sp, 0x4