/*
 * FreeRTOS Kernel <DEVELOPMENT BRANCH>
 * Copyright (C) 2021 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
 *
 * SPDX-License-Identifier: MIT
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * https://www.FreeRTOS.org
 * https://github.com/FreeRTOS
 *
 */

/* Standard includes. */
#include <stdint.h>

/* Defining MPU_WRAPPERS_INCLUDED_FROM_API_FILE ensures that PRIVILEGED_FUNCTION
 * is defined correctly and privileged functions are placed in correct sections. */
#define MPU_WRAPPERS_INCLUDED_FROM_API_FILE

/* Portasm includes. */
#include "portasm.h"

/* MPU_WRAPPERS_INCLUDED_FROM_API_FILE is needed to be defined only for the
 * header files. */
#undef MPU_WRAPPERS_INCLUDED_FROM_API_FILE

void vRestoreContextOfFirstTask( void ) /* __attribute__ (( naked )) PRIVILEGED_FUNCTION */
{
    __asm volatile
    (
        "	.syntax unified									\n"
        "													\n"
        "	ldr  r2, pxCurrentTCBConst2						\n"/* Read the location of pxCurrentTCB i.e. &( pxCurrentTCB ). */
        "	ldr  r1, [r2]									\n"/* Read pxCurrentTCB. */
        "	ldr  r0, [r1]									\n"/* Read top of stack from TCB - The first item in pxCurrentTCB is the task top of stack. */
        "													\n"
        #if ( configENABLE_MPU == 1 )
            "	dmb												\n"/* Complete outstanding transfers before disabling MPU. */
            "	ldr r2, xMPUCTRLConst2							\n"/* r2 = 0xe000ed94 [Location of MPU_CTRL]. */
            "	ldr r4, [r2]									\n"/* Read the value of MPU_CTRL. */
            "	bic r4, #1										\n"/* r4 = r4 & ~1 i.e. Clear the bit 0 in r4. */
            "	str r4, [r2]									\n"/* Disable MPU. */
            "													\n"
            "	adds r1, #4										\n"/* r1 = r1 + 4. r1 now points to MAIR0 in TCB. */
            "	ldr  r3, [r1]									\n"/* r3 = *r1 i.e. r3 = MAIR0. */
            "	ldr  r2, xMAIR0Const2							\n"/* r2 = 0xe000edc0 [Location of MAIR0]. */
            "	str  r3, [r2]									\n"/* Program MAIR0. */
            "	ldr  r2, xRNRConst2								\n"/* r2 = 0xe000ed98 [Location of RNR]. */
            "	movs r3, #4										\n"/* r3 = 4. */
            "	str  r3, [r2]									\n"/* Program RNR = 4. */
            "	adds r1, #4										\n"/* r1 = r1 + 4. r1 now points to first RBAR in TCB. */
            "	ldr  r2, xRBARConst2							\n"/* r2 = 0xe000ed9c [Location of RBAR]. */
            "	ldmia r1!, {r4-r11}								\n"/* Read 4 set of RBAR/RLAR registers from TCB. */
            "	stmia r2!, {r4-r11}								\n"/* Write 4 set of RBAR/RLAR registers using alias registers. */
            "													\n"
            "	ldr r2, xMPUCTRLConst2							\n"/* r2 = 0xe000ed94 [Location of MPU_CTRL]. */
            "	ldr r4, [r2]									\n"/* Read the value of MPU_CTRL. */
            "	orr r4, #1										\n"/* r4 = r4 | 1 i.e. Set the bit 0 in r4. */
            "	str r4, [r2]									\n"/* Enable MPU. */
            "	dsb												\n"/* Force memory writes before continuing. */
        #endif /* configENABLE_MPU */
        "													\n"
        #if ( configENABLE_MPU == 1 )
            "	ldm  r0!, {r1-r3}								\n"/* Read from stack - r1 = PSPLIM, r2 = CONTROL and r3 = EXC_RETURN. */
            "	msr  psplim, r1									\n"/* Set this task's PSPLIM value. */
            "	msr  control, r2								\n"/* Set this task's CONTROL value. */
            "	adds r0, #32									\n"/* Discard everything up to r0. */
            "	msr  psp, r0									\n"/* This is now the new top of stack to use in the task. */
            "	isb												\n"
            "	mov  r0, #0										\n"
            "	msr  basepri, r0								\n"/* Ensure that interrupts are enabled when the first task starts. */
            "	bx   r3											\n"/* Finally, branch to EXC_RETURN. */
        #else /* configENABLE_MPU */
            "	ldm  r0!, {r1-r2}								\n"/* Read from stack - r1 = PSPLIM and r2 = EXC_RETURN. */
            "	msr  psplim, r1									\n"/* Set this task's PSPLIM value. */
            "	movs r1, #2										\n"/* r1 = 2. */
            "	msr  CONTROL, r1								\n"/* Switch to use PSP in the thread mode. */
            "	adds r0, #32									\n"/* Discard everything up to r0. */
            "	msr  psp, r0									\n"/* This is now the new top of stack to use in the task. */
            "	isb												\n"
            "	mov  r0, #0										\n"
            "	msr  basepri, r0								\n"/* Ensure that interrupts are enabled when the first task starts. */
            "	bx   r2											\n"/* Finally, branch to EXC_RETURN. */
        #endif /* configENABLE_MPU */
        "													\n"
        "	.align 4										\n"
        "pxCurrentTCBConst2: .word pxCurrentTCB				\n"
        #if ( configENABLE_MPU == 1 )
            "xMPUCTRLConst2: .word 0xe000ed94					\n"
            "xMAIR0Const2: .word 0xe000edc0						\n"
            "xRNRConst2: .word 0xe000ed98						\n"
            "xRBARConst2: .word 0xe000ed9c						\n"
        #endif /* configENABLE_MPU */
    );
}
/*-----------------------------------------------------------*/

BaseType_t xIsPrivileged( void ) /* __attribute__ (( naked )) */
{
    __asm volatile
    (
        "	mrs r0, control									\n"/* r0 = CONTROL. */
        "	tst r0, #1										\n"/* Perform r0 & 1 (bitwise AND) and update the conditions flag. */
        "	ite ne											\n"
        "	movne r0, #0									\n"/* CONTROL[0]!=0. Return false to indicate that the processor is not privileged. */
        "	moveq r0, #1									\n"/* CONTROL[0]==0. Return true to indicate that the processor is privileged. */
        "	bx lr											\n"/* Return. */
        "													\n"
        "	.align 4										\n"
        ::: "r0", "memory"
    );
}
/*-----------------------------------------------------------*/

void vRaisePrivilege( void ) /* __attribute__ (( naked )) PRIVILEGED_FUNCTION */
{
    __asm volatile
    (
        "	mrs  r0, control								\n"/* Read the CONTROL register. */
        "	bic r0, #1										\n"/* Clear the bit 0. */
        "	msr  control, r0								\n"/* Write back the new CONTROL value. */
        "	bx lr											\n"/* Return to the caller. */
        ::: "r0", "memory"
    );
}
/*-----------------------------------------------------------*/

void vResetPrivilege( void ) /* __attribute__ (( naked )) */
{
    __asm volatile
    (
        "	mrs r0, control									\n"/* r0 = CONTROL. */
        "	orr r0, #1										\n"/* r0 = r0 | 1. */
        "	msr control, r0									\n"/* CONTROL = r0. */
        "	bx lr											\n"/* Return to the caller. */
        ::: "r0", "memory"
    );
}
/*-----------------------------------------------------------*/

void vStartFirstTask( void ) /* __attribute__ (( naked )) PRIVILEGED_FUNCTION */
{
    __asm volatile
    (
        "	ldr r0, xVTORConst								\n"/* Use the NVIC offset register to locate the stack. */
        "	ldr r0, [r0]									\n"/* Read the VTOR register which gives the address of vector table. */
        "	ldr r0, [r0]									\n"/* The first entry in vector table is stack pointer. */
        "	msr msp, r0										\n"/* Set the MSP back to the start of the stack. */
        "	cpsie i											\n"/* Globally enable interrupts. */
        "	cpsie f											\n"
        "	dsb												\n"
        "	isb												\n"
        "	svc %0											\n"/* System call to start the first task. */
        "	nop												\n"
        "													\n"
        "   .align 4										\n"
        "xVTORConst: .word 0xe000ed08						\n"
        ::"i" ( portSVC_START_SCHEDULER ) : "memory"
    );
}
/*-----------------------------------------------------------*/

uint32_t ulSetInterruptMask( void ) /* __attribute__(( naked )) PRIVILEGED_FUNCTION */
{
    __asm volatile
    (
        "	mrs r0, basepri									\n"/* r0 = basepri. Return original basepri value. */
        "	mov r1, %0										\n"/* r1 = configMAX_SYSCALL_INTERRUPT_PRIORITY. */
        "	msr basepri, r1									\n"/* Disable interrupts upto configMAX_SYSCALL_INTERRUPT_PRIORITY. */
        "	dsb												\n"
        "	isb												\n"
        "	bx lr											\n"/* Return. */
        ::"i" ( configMAX_SYSCALL_INTERRUPT_PRIORITY ) : "memory"
    );
}
/*-----------------------------------------------------------*/

void vClearInterruptMask( __attribute__( ( unused ) ) uint32_t ulMask ) /* __attribute__(( naked )) PRIVILEGED_FUNCTION */
{
    __asm volatile
    (
        "	msr basepri, r0									\n"/* basepri = ulMask. */
        "	dsb												\n"
        "	isb												\n"
        "	bx lr											\n"/* Return. */
        ::: "memory"
    );
}
/*-----------------------------------------------------------*/

void PendSV_Handler( void ) /* __attribute__ (( naked )) PRIVILEGED_FUNCTION */
{
    __asm volatile
    (
        "	.syntax unified									\n"
        "													\n"
        "	mrs r0, psp										\n"/* Read PSP in r0. */
        #if ( configENABLE_FPU == 1 )
            "	tst lr, #0x10									\n"/* Test Bit[4] in LR. Bit[4] of EXC_RETURN is 0 if the FPU is in use. */
            "	it eq											\n"
            "	vstmdbeq r0!, {s16-s31}							\n"/* Store the FPU registers which are not saved automatically. */
        #endif /* configENABLE_FPU */
        #if ( configENABLE_MPU == 1 )
            "	mrs r1, psplim									\n"/* r1 = PSPLIM. */
            "	mrs r2, control									\n"/* r2 = CONTROL. */
            "	mov r3, lr										\n"/* r3 = LR/EXC_RETURN. */
            "	stmdb r0!, {r1-r11}								\n"/* Store on the stack - PSPLIM, CONTROL, LR and registers that are not automatically saved. */
        #else /* configENABLE_MPU */
            "	mrs r2, psplim									\n"/* r2 = PSPLIM. */
            "	mov r3, lr										\n"/* r3 = LR/EXC_RETURN. */
            "	stmdb r0!, {r2-r11}								\n"/* Store on the stack - PSPLIM, LR and registers that are not automatically saved. */
        #endif /* configENABLE_MPU */
        "													\n"
        "	ldr r2, pxCurrentTCBConst						\n"/* Read the location of pxCurrentTCB i.e. &( pxCurrentTCB ). */
        "	ldr r1, [r2]									\n"/* Read pxCurrentTCB. */
        "	str r0, [r1]									\n"/* Save the new top of stack in TCB. */
        "													\n"
        "	mov r0, %0										\n"/* r0 = configMAX_SYSCALL_INTERRUPT_PRIORITY */
        "	msr basepri, r0									\n"/* Disable interrupts upto configMAX_SYSCALL_INTERRUPT_PRIORITY. */
        "	dsb												\n"
        "	isb												\n"
        "	bl vTaskSwitchContext							\n"
        "	mov r0, #0										\n"/* r0 = 0. */
        "	msr basepri, r0									\n"/* Enable interrupts. */
        "													\n"
        "	ldr r2, pxCurrentTCBConst						\n"/* Read the location of pxCurrentTCB i.e. &( pxCurrentTCB ). */
        "	ldr r1, [r2]									\n"/* Read pxCurrentTCB. */
        "	ldr r0, [r1]									\n"/* The first item in pxCurrentTCB is the task top of stack. r0 now points to the top of stack. */
        "													\n"
        #if ( configENABLE_MPU == 1 )
            "	dmb												\n"/* Complete outstanding transfers before disabling MPU. */
            "	ldr r2, xMPUCTRLConst							\n"/* r2 = 0xe000ed94 [Location of MPU_CTRL]. */
            "	ldr r4, [r2]									\n"/* Read the value of MPU_CTRL. */
            "	bic r4, #1										\n"/* r4 = r4 & ~1 i.e. Clear the bit 0 in r4. */
            "	str r4, [r2]									\n"/* Disable MPU. */
            "													\n"
            "	adds r1, #4										\n"/* r1 = r1 + 4. r1 now points to MAIR0 in TCB. */
            "	ldr r3, [r1]									\n"/* r3 = *r1 i.e. r3 = MAIR0. */
            "	ldr r2, xMAIR0Const								\n"/* r2 = 0xe000edc0 [Location of MAIR0]. */
            "	str r3, [r2]									\n"/* Program MAIR0. */
            "	ldr r2, xRNRConst								\n"/* r2 = 0xe000ed98 [Location of RNR]. */
            "	movs r3, #4										\n"/* r3 = 4. */
            "	str r3, [r2]									\n"/* Program RNR = 4. */
            "	adds r1, #4										\n"/* r1 = r1 + 4. r1 now points to first RBAR in TCB. */
            "	ldr r2, xRBARConst								\n"/* r2 = 0xe000ed9c [Location of RBAR]. */
            "	ldmia r1!, {r4-r11}								\n"/* Read 4 sets of RBAR/RLAR registers from TCB. */
            "	stmia r2!, {r4-r11}								\n"/* Write 4 set of RBAR/RLAR registers using alias registers. */
            "													\n"
            "	ldr r2, xMPUCTRLConst							\n"/* r2 = 0xe000ed94 [Location of MPU_CTRL]. */
            "	ldr r4, [r2]									\n"/* Read the value of MPU_CTRL. */
            "	orr r4, #1										\n"/* r4 = r4 | 1 i.e. Set the bit 0 in r4. */
            "	str r4, [r2]									\n"/* Enable MPU. */
            "	dsb												\n"/* Force memory writes before continuing. */
        #endif /* configENABLE_MPU */
        "													\n"
        #if ( configENABLE_MPU == 1 )
            "	ldmia r0!, {r1-r11}								\n"/* Read from stack - r1 = PSPLIM, r2 = CONTROL, r3 = LR and r4-r11 restored. */
        #else /* configENABLE_MPU */
            "	ldmia r0!, {r2-r11}								\n"/* Read from stack - r2 = PSPLIM, r3 = LR and r4-r11 restored. */
        #endif /* configENABLE_MPU */
        "													\n"
        #if ( configENABLE_FPU == 1 )
            "	tst r3, #0x10									\n"/* Test Bit[4] in LR. Bit[4] of EXC_RETURN is 0 if the FPU is in use. */
            "	it eq											\n"
            "	vldmiaeq r0!, {s16-s31}							\n"/* Restore the FPU registers which are not restored automatically. */
        #endif /* configENABLE_FPU */
        "													\n"
        #if ( configENABLE_MPU == 1 )
            "	msr psplim, r1									\n"/* Restore the PSPLIM register value for the task. */
            "	msr control, r2									\n"/* Restore the CONTROL register value for the task. */
        #else /* configENABLE_MPU */
            "	msr psplim, r2									\n"/* Restore the PSPLIM register value for the task. */
        #endif /* configENABLE_MPU */
        "	msr psp, r0										\n"/* Remember the new top of stack for the task. */
        "	bx r3											\n"
        "													\n"
        "	.align 4										\n"
        "pxCurrentTCBConst: .word pxCurrentTCB				\n"
        #if ( configENABLE_MPU == 1 )
            "xMPUCTRLConst: .word 0xe000ed94					\n"
            "xMAIR0Const: .word 0xe000edc0						\n"
            "xRNRConst: .word 0xe000ed98						\n"
            "xRBARConst: .word 0xe000ed9c						\n"
        #endif /* configENABLE_MPU */
        ::"i" ( configMAX_SYSCALL_INTERRUPT_PRIORITY )
    );
}
/*-----------------------------------------------------------*/

void SVC_Handler( void ) /* __attribute__ (( naked )) PRIVILEGED_FUNCTION */
{
    __asm volatile
    (
        "	tst lr, #4										\n"
        "	ite eq											\n"
        "	mrseq r0, msp									\n"
        "	mrsne r0, psp									\n"
        "	ldr r1, svchandler_address_const				\n"
        "	bx r1											\n"
        "													\n"
        "	.align 4										\n"
        "svchandler_address_const: .word vPortSVCHandler_C	\n"
    );
}
/*-----------------------------------------------------------*/