| /* | |
| * 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 | |
| * | |
| */ | |
| #include "FreeRTOSConfig.h" | |
| #define portCONTEXT_SIZE 132 | |
| #define portEPC_STACK_LOCATION 124 | |
| #define portSTATUS_STACK_LOCATION 128 | |
| /******************************************************************/ | |
| .macro portSAVE_CONTEXT | |
| /* Make room for the context. First save the current status so it can be | |
| manipulated, and the cause and EPC registers so their original values are | |
| captured. */ | |
| mfc0 k0, _CP0_CAUSE | |
| addiu sp, sp, -portCONTEXT_SIZE | |
| mfc0 k1, _CP0_STATUS | |
| /* Also save s6 and s5 so they can be used. Any nesting interrupts should | |
| maintain the values of these registers across the ISR. */ | |
| sw s6, 44(sp) | |
| sw s5, 40(sp) | |
| sw k1, portSTATUS_STACK_LOCATION(sp) | |
| /* Prepare to enable interrupts above the current priority. */ | |
| srl k0, k0, 0xa | |
| ins k1, k0, 10, 6 | |
| ins k1, zero, 1, 4 | |
| /* s5 is used as the frame pointer. */ | |
| add s5, zero, sp | |
| /* Check the nesting count value. */ | |
| la k0, uxInterruptNesting | |
| lw s6, (k0) | |
| /* If the nesting count is 0 then swap to the the system stack, otherwise | |
| the system stack is already being used. */ | |
| bne s6, zero, 1f | |
| nop | |
| /* Swap to the system stack. */ | |
| la sp, xISRStackTop | |
| lw sp, (sp) | |
| /* Increment and save the nesting count. */ | |
| 1: addiu s6, s6, 1 | |
| sw s6, 0(k0) | |
| /* s6 holds the EPC value, this is saved after interrupts are re-enabled. */ | |
| mfc0 s6, _CP0_EPC | |
| /* Re-enable interrupts. */ | |
| mtc0 k1, _CP0_STATUS | |
| /* Save the context into the space just created. s6 is saved again | |
| here as it now contains the EPC value. No other s registers need be | |
| saved. */ | |
| sw ra, 120(s5) | |
| sw s8, 116(s5) | |
| sw t9, 112(s5) | |
| sw t8, 108(s5) | |
| sw t7, 104(s5) | |
| sw t6, 100(s5) | |
| sw t5, 96(s5) | |
| sw t4, 92(s5) | |
| sw t3, 88(s5) | |
| sw t2, 84(s5) | |
| sw t1, 80(s5) | |
| sw t0, 76(s5) | |
| sw a3, 72(s5) | |
| sw a2, 68(s5) | |
| sw a1, 64(s5) | |
| sw a0, 60(s5) | |
| sw v1, 56(s5) | |
| sw v0, 52(s5) | |
| sw s6, portEPC_STACK_LOCATION(s5) | |
| sw $1, 16(s5) | |
| /* s6 is used as a scratch register. */ | |
| mfhi s6 | |
| sw s6, 12(s5) | |
| mflo s6 | |
| sw s6, 8(s5) | |
| /* Update the task stack pointer value if nesting is zero. */ | |
| la s6, uxInterruptNesting | |
| lw s6, (s6) | |
| addiu s6, s6, -1 | |
| bne s6, zero, 1f | |
| nop | |
| /* Save the stack pointer. */ | |
| la s6, uxSavedTaskStackPointer | |
| sw s5, (s6) | |
| 1: | |
| .endm | |
| /******************************************************************/ | |
| .macro portRESTORE_CONTEXT | |
| /* Restore the stack pointer from the TCB. This is only done if the | |
| nesting count is 1. */ | |
| la s6, uxInterruptNesting | |
| lw s6, (s6) | |
| addiu s6, s6, -1 | |
| bne s6, zero, 1f | |
| nop | |
| la s6, uxSavedTaskStackPointer | |
| lw s5, (s6) | |
| /* Restore the context. */ | |
| 1: lw s6, 8(s5) | |
| mtlo s6 | |
| lw s6, 12(s5) | |
| mthi s6 | |
| lw $1, 16(s5) | |
| /* s6 is loaded as it was used as a scratch register and therefore saved | |
| as part of the interrupt context. */ | |
| lw s6, 44(s5) | |
| lw v0, 52(s5) | |
| lw v1, 56(s5) | |
| lw a0, 60(s5) | |
| lw a1, 64(s5) | |
| lw a2, 68(s5) | |
| lw a3, 72(s5) | |
| lw t0, 76(s5) | |
| lw t1, 80(s5) | |
| lw t2, 84(s5) | |
| lw t3, 88(s5) | |
| lw t4, 92(s5) | |
| lw t5, 96(s5) | |
| lw t6, 100(s5) | |
| lw t7, 104(s5) | |
| lw t8, 108(s5) | |
| lw t9, 112(s5) | |
| lw s8, 116(s5) | |
| lw ra, 120(s5) | |
| /* Protect access to the k registers, and others. */ | |
| di | |
| ehb | |
| /* Decrement the nesting count. */ | |
| la k0, uxInterruptNesting | |
| lw k1, (k0) | |
| addiu k1, k1, -1 | |
| sw k1, 0(k0) | |
| lw k0, portSTATUS_STACK_LOCATION(s5) | |
| lw k1, portEPC_STACK_LOCATION(s5) | |
| /* Leave the stack in its original state. First load sp from s5, then | |
| restore s5 from the stack. */ | |
| add sp, zero, s5 | |
| lw s5, 40(sp) | |
| addiu sp, sp, portCONTEXT_SIZE | |
| mtc0 k0, _CP0_STATUS | |
| mtc0 k1, _CP0_EPC | |
| ehb | |
| eret | |
| nop | |
| .endm | |