/*----------------------------------------------------------------------------
 *      RL-ARM - RTX
 *----------------------------------------------------------------------------
 *      Name:    HAL_CA9.c
 *      Purpose: Hardware Abstraction Layer for Cortex-A9
 *      Rev.:    3 Sept 2013
 *----------------------------------------------------------------------------
 *
 * Copyright (c) 2012 - 2013 ARM Limited
 * All rights reserved.
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *  - Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *  - Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *  - Neither the name of ARM  nor the names of its contributors may be used 
 *    to endorse or promote products derived from this software without 
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDERS AND CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *---------------------------------------------------------------------------*/

#include "rt_TypeDef.h"
#include "RTX_Config.h"
#include "rt_System.h"
#include "rt_Task.h"
#include "rt_List.h"
#include "rt_MemBox.h"
#include "rt_HAL_CA.h"


/*----------------------------------------------------------------------------
 *      Functions
 *---------------------------------------------------------------------------*/

//For A-class, set USR/SYS stack
__asm void rt_set_PSP (U32 stack) {
        ARM

        MRS     R1, CPSR
        CPS     #MODE_SYS   ;no effect in USR mode
        ISB
        MOV     SP, R0
        MSR     CPSR_c, R1  ;no effect in USR mode
        ISB
        BX      LR

}

//For A-class, get USR/SYS stack
__asm U32 rt_get_PSP (void) {
        ARM

        MRS     R1, CPSR
        CPS     #MODE_SYS   ;no effect in USR mode
        ISB
        MOV     R0, SP
        MSR     CPSR_c, R1  ;no effect in USR mode
        ISB
        BX      LR
}

/*--------------------------- _alloc_box ------------------------------------*/
__asm void *_alloc_box (void *box_mem) {
    /* Function wrapper for Unprivileged/Privileged mode. */
        ARM

        LDR     R12,=__cpp(rt_alloc_box)
        MRS     R2, CPSR
        LSLS    R2, #28
        BXNE    R12
        SVC     0
        BX      LR
}


/*--------------------------- _free_box -------------------------------------*/
__asm int _free_box (void *box_mem, void *box) {
   /* Function wrapper for Unprivileged/Privileged mode. */
        ARM

        LDR     R12,=__cpp(rt_free_box)
        MRS     R2, CPSR
        LSLS    R2, #28
        BXNE    R12
        SVC     0
        BX      LR

}

/*-------------------------- SVC_Handler -----------------------------------*/

#pragma push
#pragma arm
__asm void SVC_Handler (void) {
        PRESERVE8
        ARM

        IMPORT  rt_tsk_lock
        IMPORT  rt_tsk_unlock
        IMPORT  SVC_Count
        IMPORT  SVC_Table
        IMPORT  rt_stk_check
        IMPORT  FPUEnable

Mode_SVC        EQU     0x13

        SRSFD   SP!, #Mode_SVC         ; Push LR_SVC and SPRS_SVC onto SVC mode stack
        PUSH    {R4}                   ; Push R4 so we can use it as a temp

        MRS     R4,SPSR                ; Get SPSR
        TST     R4,#CPSR_T_BIT         ; Check Thumb Bit
        LDRNEH  R4,[LR,#-2]            ; Thumb: Load Halfword
        BICNE   R4,R4,#0xFF00          ;        Extract SVC Number
        LDREQ   R4,[LR,#-4]            ; ARM:   Load Word
        BICEQ   R4,R4,#0xFF000000      ;        Extract SVC Number

        /* Lock out systick and re-enable interrupts */
        PUSH    {R0-R3,R12,LR}

        AND     R12, SP, #4            ; Ensure stack is 8-byte aligned
        SUB     SP, SP, R12            ; Adjust stack
        PUSH    {R12, LR}              ; Store stack adjustment and dummy LR to SVC stack

        BLX     rt_tsk_lock
        CPSIE   i

        POP     {R12, LR}              ; Get stack adjustment & discard dummy LR
        ADD     SP, SP, R12            ; Unadjust stack

        POP     {R0-R3,R12,LR}

        CMP     R4,#0
        BNE     SVC_User

        MRS     R4,SPSR
        PUSH    {R4}                    ; Push R4 so we can use it as a temp
        AND     R4, SP, #4              ; Ensure stack is 8-byte aligned
        SUB     SP, SP, R4              ; Adjust stack
        PUSH    {R4, LR}                ; Store stack adjustment and dummy LR
        BLX     R12
        POP     {R4, LR}                ; Get stack adjustment & discard dummy LR
        ADD     SP, SP, R4              ; Unadjust stack
        POP     {R4}                    ; Restore R4
        MSR     SPSR_CXSF,R4

        /* Here we will be in SVC mode (even if coming in from PendSV_Handler or OS_Tick_Handler) */
Sys_Switch
        LDR     LR,=__cpp(&os_tsk)
        LDM     LR,{R4,LR}              ; os_tsk.run, os_tsk.new
        CMP     R4,LR
        BNE     switching

        PUSH    {R0-R3,R12,LR}

        AND     R12, SP, #4             ; Ensure stack is 8-byte aligned
        SUB     SP, SP, R12             ; Adjust stack
        PUSH    {R12, LR}               ; Store stack adjustment and dummy LR to SVC stack

        CPSID   i
        BLX     rt_tsk_unlock

        POP     {R12, LR}               ; Get stack adjustment & discard dummy LR
        ADD     SP, SP, R12             ; Unadjust stack

        POP     {R0-R3,R12,LR}
        POP     {R4}
        RFEFD   SP!                     ; Return from exception, no task switch

switching
        CLREX
        CMP     R4,#0
        ADDEQ   SP,SP,#12               ; Original R4, LR & SPSR do not need to be popped when we are paging in a different task
        BEQ     SVC_Next                ; Runtask deleted?


        PUSH    {R8-R11} //R4 and LR already stacked
        MOV     R10,R4                  ; Preserve os_tsk.run
        MOV     R11,LR                  ; Preserve os_tsk.new

        ADD     R8,SP,#16               ; Unstack R4,LR
        LDMIA   R8,{R4,LR}

        SUB     SP,SP,#4                ; Make space on the stack for the next instn
        STMIA   SP,{SP}^                ; Put User SP onto stack
        POP     {R8}                    ; Pop User SP into R8

        MRS     R9,SPSR
        STMDB   R8!,{R9}                ; User CPSR
        STMDB   R8!,{LR}                ; User PC
        STMDB   R8,{LR}^                ; User LR
        SUB     R8,R8,#4                ; No writeback for store of User LR
        STMDB   R8!,{R0-R3,R12}         ; User R0-R3,R12
        MOV     R3,R10                  ; os_tsk.run
        MOV     LR,R11                  ; os_tsk.new
        POP     {R9-R12}
        ADD     SP,SP,#12               ; Fix up SP for unstack of R4, LR & SPSR
        STMDB   R8!,{R4-R7,R9-R12}      ; User R4-R11

        //If applicable, stack VFP state
        MRC     p15,0,R1,c1,c0,2        ; VFP/NEON access enabled? (CPACR)
        AND     R2,R1,#0x00F00000
        CMP     R2,#0x00F00000
        BNE     no_outgoing_vfp
        VMRS    R2,FPSCR
        STMDB   R8!,{R2,R4}             ; Push FPSCR, maintain 8-byte alignment
        VSTMDB  R8!,{S0-S31}
        LDRB    R2,[R3,#TCB_STACKF]     ; Record in TCB that VFP state is stacked
        ORR     R2,#2
        STRB    R2,[R3,#TCB_STACKF]

no_outgoing_vfp
        STR     R8,[R3,#TCB_TSTACK]
        MOV     R4,LR

        PUSH    {R4}                    ; Push R4 so we can use it as a temp
        AND     R4, SP, #4              ; Ensure stack is 8-byte aligned
        SUB     SP, SP, R4              ; Adjust stack
        PUSH    {R4, LR}                ; Store stack adjustment and dummy LR to SVC stack

        BLX     rt_stk_check

        POP     {R4, LR}                ; Get stack adjustment & discard dummy LR
        ADD     SP, SP, R4              ; Unadjust stack
        POP     {R4}                    ; Restore R4

        MOV     LR,R4

SVC_Next  //R4 == os_tsk.run, LR == os_tsk.new, R0-R3, R5-R12 corruptible
        LDR     R1,=__cpp(&os_tsk)      ; os_tsk.run = os_tsk.new
        STR     LR,[R1]
        LDRB    R1,[LR,#TCB_TID]        ; os_tsk.run->task_id
        LSL     R1,#8                   ; Store PROCID
        MCR     p15,0,R1,c13,c0,1       ; Write CONTEXTIDR

        LDR     R0,[LR,#TCB_TSTACK]     ; os_tsk.run->tsk_stack

        //Does incoming task have VFP state in stack?
        LDRB    R3,[LR,#TCB_STACKF]
        TST     R3,#0x2
        MRC     p15,0,R1,c1,c0,2        ; Read CPACR
        ANDEQ   R1,R1,#0xFF0FFFFF       ; Disable VFP access if incoming task does not have stacked VFP state
        ORRNE   R1,R1,#0x00F00000       ; Enable VFP access if incoming task does have stacked VFP state
        MCR     p15,0,R1,c1,c0,2        ; Write CPACR
        BEQ     no_incoming_vfp
        ISB                             ; We only need the sync if we enabled, otherwise we will context switch before next VFP instruction anyway
        VLDMIA  R0!,{S0-S31}
        LDR     R2,[R0]
        VMSR    FPSCR,R2
        ADD     R0,R0,#8

no_incoming_vfp
        LDR     R1,[R0,#60]             ; Restore User CPSR
        MSR     SPSR_CXSF,R1
        LDMIA   R0!,{R4-R11}            ; Restore User R4-R11
        ADD     R0,R0,#4                ; Restore User R1-R3,R12
        LDMIA   R0!,{R1-R3,R12}
        LDMIA   R0,{LR}^                ; Restore User LR
        ADD     R0,R0,#4                ; No writeback for load to user LR
        LDMIA   R0!,{LR}                ; Restore User PC
        ADD     R0,R0,#4                ; Correct User SP for unstacked user CPSR

        PUSH    {R0}                    ; Push R0 onto stack
        LDMIA   SP,{SP}^                ; Get R0 off stack into User SP
        ADD     SP,SP,#4                ; Put SP back

        LDR     R0,[R0,#-32]            ; Restore R0

        PUSH    {R0-R3,R12,LR}

        AND     R12, SP, #4             ; Ensure stack is 8-byte aligned
        SUB     SP, SP, R12             ; Adjust stack
        PUSH    {R12, LR}               ; Store stack adjustment and dummy LR to SVC stack

        CPSID   i
        BLX     rt_tsk_unlock

        POP     {R12, LR}               ; Get stack adjustment & discard dummy LR
        ADD     SP, SP, R12             ; Unadjust stack

        POP     {R0-R3,R12,LR}

        MOVS    PC,LR                   ; Return from exception


        /*------------------- User SVC -------------------------------*/

SVC_User
        LDR     R12,=SVC_Count
        LDR     R12,[R12]
        CMP     R4,R12                  ; Check for overflow
        BHI     SVC_Done

        LDR     R12,=SVC_Table-4
        LDR     R12,[R12,R4,LSL #2]     ; Load SVC Function Address
        MRS     R4,SPSR                 ; Save SPSR
        PUSH    {R4}                    ; Push R4 so we can use it as a temp
        AND     R4, SP, #4              ; Ensure stack is 8-byte aligned
        SUB     SP, SP, R4              ; Adjust stack
        PUSH    {R4, LR}                ; Store stack adjustment and dummy LR
        BLX     R12                     ; Call SVC Function
        POP     {R4, LR}                ; Get stack adjustment & discard dummy LR
        ADD     SP, SP, R4              ; Unadjust stack
        POP     {R4}                    ; Restore R4
        MSR     SPSR_CXSF,R4            ; Restore SPSR

SVC_Done
        PUSH    {R0-R3,R12,LR}

        PUSH    {R4}                    ; Push R4 so we can use it as a temp
        AND     R4, SP, #4              ; Ensure stack is 8-byte aligned
        SUB     SP, SP, R4              ; Adjust stack
        PUSH    {R4, LR}                ; Store stack adjustment and dummy LR

        CPSID   i
        BLX     rt_tsk_unlock

        POP     {R4, LR}                ; Get stack adjustment & discard dummy LR
        ADD     SP, SP, R4              ; Unadjust stack
        POP     {R4}                    ; Restore R4

        POP     {R0-R3,R12,LR}
        POP     {R4}
        RFEFD   SP!                     ; Return from exception
}
#pragma pop

#pragma push
#pragma arm
__asm void PendSV_Handler (U32 IRQn) {
    ARM

    IMPORT  rt_tsk_lock
    IMPORT  IRQNestLevel

    ADD     SP,SP,#8 //fix up stack pointer (R0 has been pushed and will never be popped, R1 was pushed for stack alignment)

    //Disable systick interrupts, then write EOIR. We want interrupts disabled before we enter the context switcher.
    PUSH    {R0, R1}
    BLX     rt_tsk_lock
    POP     {R0, R1}
    LDR     R1, =__cpp(&GICInterface_BASE)
    LDR     R1, [R1, #0]
    STR     R0, [R1, #0x10]

    LDR     R0, =IRQNestLevel           ; Get address of nesting counter
    LDR     R1, [R0]
    SUB     R1, R1, #1                  ; Decrement nesting counter
    STR     R1, [R0]

    BLX     __cpp(rt_pop_req)

    POP     {R1, LR}                ; Get stack adjustment & discard dummy LR
    ADD     SP, SP, R1              ; Unadjust stack

    LDR     R0,[SP,#24]
    MSR     SPSR_CXSF,R0
    POP     {R0-R3,R12}             ; Leave SPSR & LR on the stack
    PUSH    {R4}
    B       Sys_Switch
}
#pragma pop


#pragma push
#pragma arm
__asm void OS_Tick_Handler (U32 IRQn) {
    ARM

    IMPORT  rt_tsk_lock
    IMPORT  IRQNestLevel

    ADD     SP,SP,#8 //fix up stack pointer (R0 has been pushed and will never be popped, R1 was pushed for stack alignment)

    PUSH    {R0, R1}
    BLX     rt_tsk_lock
    POP     {R0, R1}
    LDR     R1, =__cpp(&GICInterface_BASE)
    LDR     R1, [R1, #0]
    STR     R0, [R1, #0x10]

    LDR     R0, =IRQNestLevel           ; Get address of nesting counter
    LDR     R1, [R0]
    SUB     R1, R1, #1                  ; Decrement nesting counter
    STR     R1, [R0]

    BLX      __cpp(os_tick_irqack)
    BLX      __cpp(rt_systick)

    POP     {R1, LR}                ; Get stack adjustment & discard dummy LR
    ADD     SP, SP, R1              ; Unadjust stack

    LDR     R0,[SP,#24]
    MSR     SPSR_CXSF,R0
    POP     {R0-R3,R12}             ; Leave SPSR & LR on the stack
    PUSH    {R4}
    B       Sys_Switch
}
#pragma pop


/*----------------------------------------------------------------------------
 * end of file
 *---------------------------------------------------------------------------*/
