/* FreeRTOS.org V5.2.0 - Copyright (C) 2003-2009 Richard Barry. This file is part of the FreeRTOS.org distribution. FreeRTOS.org is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License (version 2) as published by the Free Software Foundation and modified by the FreeRTOS exception. FreeRTOS.org is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. A special exception to the GPL is included to allow you to distribute a combined work that includes FreeRTOS.org without being obliged to provide the source code for any proprietary components. See the licensing section of http://www.FreeRTOS.org for full details. *************************************************************************** * * * Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation * * * * This is a concise, step by step, 'hands on' guide that describes both * * general multitasking concepts and FreeRTOS specifics. It presents and * * explains numerous examples that are written using the FreeRTOS API. * * Full source code for all the examples is provided in an accompanying * * .zip file. * * * *************************************************************************** 1 tab == 4 spaces! Please ensure to read the configuration and relevant port sections of the online documentation. http://www.FreeRTOS.org - Documentation, latest information, license and contact details. http://www.SafeRTOS.com - A version that is certified for use in safety critical systems. http://www.OpenRTOS.com - Commercial support, development, porting, licensing and training services. */ #include #include #include "ISR_Support.h" .set nomips16 .set noreorder .extern pxCurrentTCB .extern vTaskSwitchContext .extern vPortIncrementTick .extern xISRStackTop .global vPortStartFirstTask .global vPortYieldISR .global vT1InterruptHandler /******************************************************************/ .section .FreeRTOS, "ax", @progbits .set noreorder .set noat .ent vT1InterruptHandler vT1InterruptHandler: portSAVE_CONTEXT jal vPortIncrementTick nop portRESTORE_CONTEXT .end vT1InterruptHandler /******************************************************************/ .section .FreeRTOS, "ax", @progbits .set noreorder .set noat .ent xPortStartScheduler vPortStartFirstTask: /* Simply restore the context of the highest priority task that has been created so far. */ portRESTORE_CONTEXT .end xPortStartScheduler /*******************************************************************/ .section .FreeRTOS, "ax", @progbits .set noreorder .set noat .ent vPortYieldISR vPortYieldISR: /* Make room for the context. First save the current status so we can manipulate it, and the cause and EPC registers so we capture their original values in case of interrupt nesting. */ mfc0 k0, _CP0_CAUSE addiu sp, sp, -portCONTEXT_SIZE mfc0 k1, _CP0_STATUS /* Also save s6 and s5 so we can use them during this interrupt. 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) /* 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 /* Swap to the system stack. This is not conditional on the nesting count as this interrupt is always the lowest priority and therefore the nesting is always 0. */ la sp, xISRStackTop lw sp, (sp) /* Set the nesting count. */ la k0, uxInterruptNesting addiu s6, zero, 1 sw s6, 0(k0) /* s6 holds the EPC value, this is saved with the rest of the context after interrupts are 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. */ 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 s7, 48(s5) sw s6, portEPC_STACK_LOCATION(s5) /* s5 and s6 has already been saved. */ sw s4, 36(s5) sw s3, 32(s5) sw s2, 28(s5) sw s1, 24(s5) sw s0, 20(s5) sw $1, 16(s5) /* s7 is used as a scratch register as this should always be saved across nesting interrupts. */ mfhi s7 sw s7, 12(s5) mflo s7 sw s7, 8(s5) /* Save the stack pointer to the task. */ la s7, pxCurrentTCB lw s7, (s7) sw s5, (s7) /* Set the interrupt mask to the max priority that can use the API. */ di mfc0 s7, _CP0_STATUS ori s7, s7, 1 ori s6, s7, configMAX_SYSCALL_INTERRUPT_PRIORITY << 10 /* This mtc0 re-enables interrupts, but only above configMAX_SYSCALL_INTERRUPT_PRIORITY. */ mtc0 s6, _CP0_STATUS /* Clear the software interrupt in the core. */ mfc0 s6, _CP0_CAUSE addiu s4,zero,-257 and s6, s6, s4 mtc0 s6, _CP0_CAUSE /* Clear the interrupt in the interrupt controller. */ la s6, IFS0CLR addiu s4, zero, 2 sw s4, (s6) jal vTaskSwitchContext nop /* Clear the interrupt mask again. The saved status value is still in s7. */ mtc0 s7, _CP0_STATUS /* Restore the stack pointer from the TCB. */ la s0, pxCurrentTCB lw s0, (s0) lw s5, (s0) /* Restore the rest of the context. */ lw s0, 8(s5) mtlo s0 lw s0, 12(s5) mthi s0 lw $1, 16(s5) lw s0, 20(s5) lw s1, 24(s5) lw s2, 28(s5) lw s3, 32(s5) lw s4, 36(s5) /* s5 is loaded later. */ lw s6, 44(s5) lw s7, 48(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 /* Set nesting back to zero. As the lowest priority interrupt this interrupt cannot have nested. */ la k0, uxInterruptNesting sw zero, 0(k0) /* Switch back to use the real stack pointer. */ add sp, zero, s5 /* Restore the real s5 value. */ lw s5, 40(sp) /* Pop the status and epc values. */ lw k1, portSTATUS_STACK_LOCATION(sp) lw k0, portEPC_STACK_LOCATION(sp) /* Remove stack frame. */ addiu sp, sp, portCONTEXT_SIZE mtc0 k1, _CP0_STATUS ehb mtc0 k0, _CP0_EPC eret nop .end vPortYieldISR