389 lines
11 KiB
ArmAsm
389 lines
11 KiB
ArmAsm
/*
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* Copyright (c) 2016 Cadence Design Systems, Inc.
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <xtensa_context.h>
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#include <xtensa_timer.h>
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#include <offsets_short.h>
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#include <kernel_structs.h>
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.extern _interrupt_stack
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.extern _kernel
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#ifdef CONFIG_SYS_CLOCK_EXISTS
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.extern _timer_int_handler
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#endif
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.set _interrupt_stack_top, _interrupt_stack + CONFIG_ISR_STACK_SIZE
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/*
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* _zxt_dispatch(_kernel_t *_kernel, _thread_t *_thread)
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* At this point, the a2 register contains the '&_kernel' and the
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* thread to be swapped in (&_thread) is in a3.
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*/
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.text
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.globl _zxt_dispatch
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.type _zxt_dispatch,@function
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.align 4
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_zxt_dispatch:
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/* Updated current thread: _kernel.current := _kernel.ready_q.cache */
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s32i a3, a2, KERNEL_OFFSET(current) /* _kernel.current := _thread */
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l32i sp, a3, THREAD_OFFSET(sp) /* sp := _thread->topOfStack; */
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/* Determine the type of stack frame. */
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l32i a2, sp, XT_STK_exit /* exit dispatcher or solicited flag */
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bnez a2, .L_frxt_dispatch_stk
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.L_frxt_dispatch_sol:
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/* Solicited stack frame. Restore retval from _Swap */
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l32i a2, a3, THREAD_OFFSET(retval)
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l32i a3, sp, XT_SOL_ps
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#ifdef __XTENSA_CALL0_ABI__
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l32i a12, sp, XT_SOL_a12
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l32i a13, sp, XT_SOL_a13
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l32i a14, sp, XT_SOL_a14
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l32i a15, sp, XT_SOL_a15
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#endif
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l32i a0, sp, XT_SOL_pc
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#if XCHAL_CP_NUM > 0
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/* Ensure wsr.CPENABLE is complete (should be, it was cleared on
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* entry).
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*/
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rsync
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#endif
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/* As soons as PS is restored, interrupts can happen. No need to sync
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* PS.
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*/
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wsr a3, PS
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#ifdef __XTENSA_CALL0_ABI__
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addi sp, sp, XT_SOL_FRMSZ
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ret
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#else
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retw
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#endif
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.L_frxt_dispatch_stk:
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#if XCHAL_CP_NUM > 0
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/* Restore CPENABLE from task's co-processor save area. */
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l32i a2, a3, THREAD_OFFSET(cpStack)
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l16ui a3, a2, XT_CPENABLE
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wsr a3, CPENABLE
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#endif
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/*
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* Interrupt stack frame.
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* Restore full context and return to exit dispatcher.
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*/
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call0 _xt_context_restore
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/* In Call0 ABI, restore callee-saved regs (A12, A13 already
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* restored).
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*/
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#ifdef __XTENSA_CALL0_ABI__
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l32i a14, sp, XT_STK_a14
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l32i a15, sp, XT_STK_a15
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#endif
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#if XCHAL_CP_NUM > 0
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/* Ensure wsr.CPENABLE has completed. */
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rsync
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#endif
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/*
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* Must return via the exit dispatcher corresponding to the entrypoint
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* from which this was called. Interruptee's A0, A1, PS, PC are
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* restored and the interrupt stack frame is deallocated in the exit
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* dispatcher.
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*/
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l32i a0, sp, XT_STK_exit
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ret
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/*
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* _zxt_int_enter
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* void _zxt_int_enter(void)
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*
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* Implements the Xtensa RTOS porting layer's XT_RTOS_INT_ENTER function for
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* freeRTOS. Saves the rest of the interrupt context (not already saved).
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* May only be called from assembly code by the 'call0' instruction, with
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* interrupts disabled.
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* See the detailed description of the XT_RTOS_ENTER macro in xtensa_rtos.h.
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*/
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.globl _zxt_int_enter
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.type _zxt_int_enter,@function
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.align 4
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_zxt_int_enter:
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/* Save a12-13 in the stack frame as required by _xt_context_save. */
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s32i a12, a1, XT_STK_a12
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s32i a13, a1, XT_STK_a13
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/* Save return address in a safe place (free a0). */
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mov a12, a0
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/* Save the rest of the interrupted context (preserves A12-13). */
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call0 _xt_context_save
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/*
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* Save interrupted task's SP in TCB only if not nesting. Manage
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* nesting directly rather than call the generic IntEnter() (in
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* windowed ABI we can't call a C function here anyway because PS.EXCM
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* is still set).
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*/
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movi a2, _kernel /* a2 := _kernel */
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l32i a3, a2, KERNEL_OFFSET(nested) /* a3 := _kernel->nested */
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addi a3, a3, 1 /* increment nesting count */
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s32i a3, a2, KERNEL_OFFSET(nested) /* save nesting count */
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bnei a3, 1, .Lnested /* !=0 before incr, so nested */
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l32i a3, a2, KERNEL_OFFSET(current)/* a3 := _kernel->current */
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s32i a1, a3, THREAD_OFFSET(sp) /* save SP to Current top of stack */
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movi a1, _interrupt_stack_top /* a1 = top of intr stack */
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.Lnested:
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1:
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mov a0, a12 /* restore return addr and return */
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ret
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/*
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* _zxt_int_exit
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* void _zxt_int_exit(void)
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*
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* Implements the Xtensa RTOS porting layer's XT_RTOS_INT_EXIT function for
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* Zephyr. If required, calls vPortYieldFromInt() to perform task context
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* switching, restore the (possibly) new task's context, and return to the exit
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* dispatcher saved in the task's stack frame at XT_STK_EXIT. May only be
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* called from assembly code by the 'call0' instruction. Does not return to
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* caller. See the description of the XT_RTOS_ENTER macro in xtensa_rtos.h.
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*/
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.globl _zxt_int_exit
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.type _zxt_int_exit,@function
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.align 4
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_zxt_int_exit:
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rsil a0, XCHAL_EXCM_LEVEL /* lock out interrupts */
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movi a2, _kernel
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l32i a3, a2, KERNEL_OFFSET(nested) /* _kernel->nested */
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addi a3, a3, -1 /* decrement nesting count */
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s32i a3, a2, KERNEL_OFFSET(nested) /* save nesting count */
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bnez a3, .Lnesting /* !=0 after decr so still nested */
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/*
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* When using call0 ABI callee-saved registers a12-15 need to be saved
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* before enabling preemption. They were already saved by
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* _zxt_int_enter().
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*/
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#ifdef __XTENSA_CALL0_ABI__
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s32i a14, a1, XT_STK_a14
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s32i a15, a1, XT_STK_a15
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#endif
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#if XCHAL_CP_NUM > 0
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l32i a3, a2, KERNEL_OFFSET(current) /* _thread := _kernel->current */
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l32i a4, a3, THREAD_OFFSET(cpStack)
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rsr a5, CPENABLE
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s16i a5, a4, XT_CPENABLE /* cp_state->cpenable = CPENABLE; */
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movi a3, 0
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wsr a3, CPENABLE /* disable all co-processors */
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#endif
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l32i a3, a2, KERNEL_OFFSET(current) /* _thread := _kernel.current */
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/*
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* Non-preemptible thread ? Do not schedule (see explanation of
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* preempt field in kernel_struct.h).
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*/
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movi a4, _NON_PREEMPT_THRESHOLD
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l16ui a5, a3, THREAD_OFFSET(preempt)
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bgeu a5, a4, .noReschedule
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/* _thread := _kernel.ready_q.cache */
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l32i a3, a2, KERNEL_OFFSET(ready_q_cache)
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.noReschedule:
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/*
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* Swap threads if any is to be swapped in.
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*/
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call0 _zxt_dispatch /* (_kernel@a2, _thread@a3) */
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/* Never returns here. */
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.Lnesting:
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/*
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* We come here only if there was no context switch, that is if this
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* is a nested interrupt, or the interrupted task was not preempted.
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* In either case there's no need to load the SP.
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*/
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/* Restore full context from interrupt stack frame */
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call0 _xt_context_restore
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/*
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* Must return via the exit dispatcher corresponding to the entrypoint
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* from which this was called. Interruptee's A0, A1, PS, PC are
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* restored and the interrupt stack frame is deallocated in the exit
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* dispatcher.
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*/
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l32i a0, sp, XT_STK_exit
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ret
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/*
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* _zxt_timer_int
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* void _zxt_timer_int(void)
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*
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* Implements Xtensa RTOS porting layer's XT_RTOS_TIMER_INT function. Called
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* every timer interrupt. Manages the tick timer and calls
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* xPortSysTickHandler() every tick. See the detailed description of the
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* XT_RTOS_ENTER macro in xtensa_rtos.h. Callable from C. Implemented in
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* assmebly code for performance.
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*
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*/
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.globl _zxt_timer_int
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.type _zxt_timer_int,@function
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.align 4
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_zxt_timer_int:
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/*
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* Xtensa timers work by comparing a cycle counter with a preset value.
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* Once the match occurs an interrupt is generated, and the handler has
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* to set a new cycle count into the comparator. To avoid clock drift
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* due to interrupt latency, the new cycle count is computed from the
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* old, not the time the interrupt was serviced. However if a timer
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* interrupt is ever serviced more than one tick late, it is necessary
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* to process multiple ticks until the new cycle count is in the
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* future, otherwise the next timer interrupt would not occur until
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* after the cycle counter had wrapped (2^32 cycles later).
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*
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* do {
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* ticks++;
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* old_ccompare = read_ccompare_i();
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* write_ccompare_i( old_ccompare + divisor );
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* service one tick;
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* diff = read_ccount() - old_ccompare;
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* } while ( diff > divisor );
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*/
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ENTRY(16)
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.L_xt_timer_int_catchup:
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#ifdef CONFIG_SYS_CLOCK_EXISTS
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#if CONFIG_XTENSA_INTERNAL_TIMER || (CONFIG_XTENSA_TIMER_IRQ < 0)
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/* Update the timer comparator for the next tick. */
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#ifdef XT_CLOCK_FREQ
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movi a2, XT_TICK_DIVISOR /* a2 = comparator increment */
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#else
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movi a3, _xt_tick_divisor
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l32i a2, a3, 0 /* a2 = comparator increment */
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#endif
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rsr a3, XT_CCOMPARE /* a3 = old comparator value */
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add a4, a3, a2 /* a4 = new comparator value */
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wsr a4, XT_CCOMPARE /* update comp. and clear interrupt */
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esync
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#endif /* CONFIG_XTENSA_INTERNAL_TIMER || (CONFIG_XTENSA_TIMER_IRQ < 0) */
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#ifdef __XTENSA_CALL0_ABI__
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/* Preserve a2 and a3 across C calls. */
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s32i a2, sp, 4
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s32i a3, sp, 8
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/* TODO: movi a2, _xt_interrupt_table */
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movi a3, _timer_int_handler
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/* TODO: l32i a2, a2, 0 */
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callx0 a3
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/* Restore a2 and a3. */
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l32i a2, sp, 4
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l32i a3, sp, 8
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#else
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/* TODO: movi a6, _xt_interrupt_table */
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movi a7, _timer_int_handler
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/* TODO: l32i a6, a6, 0 */
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callx4 a7
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#endif
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#if CONFIG_XTENSA_INTERNAL_TIMER || (CONFIG_XTENSA_TIMER_IRQ < 0)
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/* Check if we need to process more ticks to catch up. */
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esync /* ensure comparator update complete */
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rsr a4, CCOUNT /* a4 = cycle count */
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sub a4, a4, a3 /* diff = ccount - old comparator */
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blt a2, a4, .L_xt_timer_int_catchup /* repeat while diff > divisor */
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#endif /* CONFIG_XTENSA_INTERNAL_TIMER || (CONFIG_XTENSA_TIMER_IRQ < 0) */
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#endif
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RET(16)
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/*
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* _zxt_tick_timer_init
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* void _zxt_tick_timer_init(void)
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*
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* Initialize timer and timer interrupt handler (_xt_tick_divisor_init() has
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* already been been called).
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* Callable from C (obeys ABI conventions on entry).
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*
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*/
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.globl _zxt_tick_timer_init
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.type _zxt_tick_timer_init,@function
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.align 4
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_zxt_tick_timer_init:
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ENTRY(48)
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#ifdef CONFIG_SYS_CLOCK_EXISTS
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#if CONFIG_XTENSA_INTERNAL_TIMER || (CONFIG_XTENSA_TIMER_IRQ < 0)
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/* Set up the periodic tick timer (assume enough time to complete
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* init).
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*/
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#ifdef XT_CLOCK_FREQ
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movi a3, XT_TICK_DIVISOR
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#else
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movi a2, _xt_tick_divisor
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l32i a3, a2, 0
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#endif
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rsr a2, CCOUNT /* current cycle count */
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add a2, a2, a3 /* time of first timer interrupt */
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wsr a2, XT_CCOMPARE /* set the comparator */
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/*
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Enable the timer interrupt at the device level. Don't write directly
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to the INTENABLE register because it may be virtualized.
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*/
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#ifdef __XTENSA_CALL0_ABI__
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movi a2, XT_TIMER_INTEN
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call0 _xt_ints_on
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#else
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movi a6, XT_TIMER_INTEN
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call4 _xt_ints_on
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#endif
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#endif
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#endif /* CONFIG_XTENSA_INTERNAL_TIMER || (CONFIG_XTENSA_TIMER_IRQ < 0) */
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RET(48)
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/*
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* _zxt_task_coproc_state
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* void _zxt_task_coproc_state(void)
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*
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* Implements the Xtensa RTOS porting layer's XT_RTOS_CP_STATE function.
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*
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* May only be called when a task is running, not within an interrupt handler
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* (returns 0 in that case).
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* May only be called from assembly code by the 'call0' instruction.
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* Does NOT obey ABI conventions.
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* Returns in A15 a pointer to the base of the co-processor state save area
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* for the current task.
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* See the detailed description of the XT_RTOS_ENTER macro in xtensa_rtos.h.
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*
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*/
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#if XCHAL_CP_NUM > 0
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.globl _zxt_task_coproc_state
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.type _zxt_task_coproc_state,@function
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.align 4
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_zxt_task_coproc_state:
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movi a2, _kernel
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l32i a15, a2, KERNEL_OFFSET(nested)
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bnez a15, 1f
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l32i a2, a2, KERNEL_OFFSET(current)
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beqz a2, 1f
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l32i a15, a2, THREAD_OFFSET(cpStack)
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ret
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1: movi a15, 0
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2: ret
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#endif /* XCHAL_CP_NUM > 0 */
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