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Rohit Grover
Diff: Source/portable/RVDS/ARM_CM0/port.c
- Revision:
- 1:fc62ab66aa39
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/Source/portable/RVDS/ARM_CM0/port.c Fri Mar 02 09:46:03 2018 +0000
@@ -0,0 +1,340 @@
+/*
+ FreeRTOS V7.6.0 - Copyright (C) 2013 Real Time Engineers Ltd.
+ All rights reserved
+
+ VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
+
+ ***************************************************************************
+ * *
+ * FreeRTOS provides completely free yet professionally developed, *
+ * robust, strictly quality controlled, supported, and cross *
+ * platform software that has become a de facto standard. *
+ * *
+ * Help yourself get started quickly and support the FreeRTOS *
+ * project by purchasing a FreeRTOS tutorial book, reference *
+ * manual, or both from: http://www.FreeRTOS.org/Documentation *
+ * *
+ * Thank you! *
+ * *
+ ***************************************************************************
+
+ This file is part of the FreeRTOS distribution.
+
+ FreeRTOS 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.
+
+ >>! NOTE: The modification to the GPL is included to allow you to distribute
+ >>! a combined work that includes FreeRTOS without being obliged to provide
+ >>! the source code for proprietary components outside of the FreeRTOS
+ >>! kernel.
+
+ FreeRTOS 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. Full license text is available from the following
+ link: http://www.freertos.org/a00114.html
+
+ 1 tab == 4 spaces!
+
+ ***************************************************************************
+ * *
+ * Having a problem? Start by reading the FAQ "My application does *
+ * not run, what could be wrong?" *
+ * *
+ * http://www.FreeRTOS.org/FAQHelp.html *
+ * *
+ ***************************************************************************
+
+ http://www.FreeRTOS.org - Documentation, books, training, latest versions,
+ license and Real Time Engineers Ltd. contact details.
+
+ http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
+ including FreeRTOS+Trace - an indispensable productivity tool, a DOS
+ compatible FAT file system, and our tiny thread aware UDP/IP stack.
+
+ http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
+ Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS
+ licenses offer ticketed support, indemnification and middleware.
+
+ http://www.SafeRTOS.com - High Integrity Systems also provide a safety
+ engineered and independently SIL3 certified version for use in safety and
+ mission critical applications that require provable dependability.
+
+ 1 tab == 4 spaces!
+*/
+
+/*-----------------------------------------------------------
+ * Implementation of functions defined in portable.h for the ARM CM0 port.
+ *----------------------------------------------------------*/
+
+/* Scheduler includes. */
+#include "FreeRTOS.h"
+#include "task.h"
+
+/* Constants required to manipulate the NVIC. */
+#define portNVIC_SYSTICK_CTRL ( ( volatile unsigned long *) 0xe000e010 )
+#define portNVIC_SYSTICK_LOAD ( ( volatile unsigned long *) 0xe000e014 )
+#define portNVIC_INT_CTRL ( ( volatile unsigned long *) 0xe000ed04 )
+#define portNVIC_SYSPRI2 ( ( volatile unsigned long *) 0xe000ed20 )
+#define portNVIC_SYSTICK_CLK 0x00000004
+#define portNVIC_SYSTICK_INT 0x00000002
+#define portNVIC_SYSTICK_ENABLE 0x00000001
+#define portNVIC_PENDSVSET 0x10000000
+#define portMIN_INTERRUPT_PRIORITY ( 255UL )
+#define portNVIC_PENDSV_PRI ( portMIN_INTERRUPT_PRIORITY << 16UL )
+#define portNVIC_SYSTICK_PRI ( portMIN_INTERRUPT_PRIORITY << 24UL )
+
+/* Constants required to set up the initial stack. */
+#define portINITIAL_XPSR ( 0x01000000 )
+
+/* Constants used with memory barrier intrinsics. */
+#define portSY_FULL_READ_WRITE ( 15 )
+
+/* Each task maintains its own interrupt status in the critical nesting
+variable. */
+static unsigned portBASE_TYPE uxCriticalNesting = 0xaaaaaaaa;
+
+/*
+ * Setup the timer to generate the tick interrupts.
+ */
+static void prvSetupTimerInterrupt( void );
+
+/*
+ * Exception handlers.
+ */
+void xPortPendSVHandler( void );
+void xPortSysTickHandler( void );
+void vPortSVCHandler( void );
+
+/*
+ * Start first task is a separate function so it can be tested in isolation.
+ */
+static void prvPortStartFirstTask( void );
+
+/*
+ * Used to catch tasks that attempt to return from their implementing function.
+ */
+static void prvTaskExitError( void );
+
+/*-----------------------------------------------------------*/
+
+/*
+ * See header file for description.
+ */
+portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
+{
+ /* Simulate the stack frame as it would be created by a context switch
+ interrupt. */
+ pxTopOfStack--; /* Offset added to account for the way the MCU uses the stack on entry/exit of interrupts. */
+ *pxTopOfStack = portINITIAL_XPSR; /* xPSR */
+ pxTopOfStack--;
+ *pxTopOfStack = ( portSTACK_TYPE ) pxCode; /* PC */
+ pxTopOfStack--;
+ *pxTopOfStack = ( portSTACK_TYPE ) prvTaskExitError; /* LR */
+ pxTopOfStack -= 5; /* R12, R3, R2 and R1. */
+ *pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */
+ pxTopOfStack -= 8; /* R11..R4. */
+
+ return pxTopOfStack;
+}
+/*-----------------------------------------------------------*/
+
+static void prvTaskExitError( void )
+{
+ /* A function that implements a task must not exit or attempt to return to
+ its caller as there is nothing to return to. If a task wants to exit it
+ should instead call vTaskDelete( NULL ).
+
+ Artificially force an assert() to be triggered if configASSERT() is
+ defined, then stop here so application writers can catch the error. */
+ configASSERT( uxCriticalNesting == ~0UL );
+ portDISABLE_INTERRUPTS();
+ for( ;; );
+}
+/*-----------------------------------------------------------*/
+
+void vPortSVCHandler( void )
+{
+ /* This function is no longer used, but retained for backward
+ compatibility. */
+}
+/*-----------------------------------------------------------*/
+
+__asm void prvPortStartFirstTask( void )
+{
+ extern pxCurrentTCB;
+
+ PRESERVE8
+
+ /* The MSP stack is not reset as, unlike on M3/4 parts, there is no vector
+ table offset register that can be used to locate the initial stack value.
+ Not all M0 parts have the application vector table at address 0. */
+
+ ldr r3, =pxCurrentTCB /* Obtain location of pxCurrentTCB. */
+ ldr r1, [r3]
+ ldr r0, [r1] /* The first item in pxCurrentTCB is the task top of stack. */
+ adds r0, #32 /* Discard everything up to r0. */
+ msr psp, r0 /* This is now the new top of stack to use in the task. */
+ movs r0, #2 /* Switch to the psp stack. */
+ msr CONTROL, r0
+ pop {r0-r5} /* Pop the registers that are saved automatically. */
+ mov lr, r5 /* lr is now in r5. */
+ cpsie i /* The first task has its context and interrupts can be enabled. */
+ pop {pc} /* Finally, pop the PC to jump to the user defined task code. */
+
+ ALIGN
+}
+/*-----------------------------------------------------------*/
+
+/*
+ * See header file for description.
+ */
+portBASE_TYPE xPortStartScheduler( void )
+{
+ /* Make PendSV, CallSV and SysTick the same priroity as the kernel. */
+ *(portNVIC_SYSPRI2) |= portNVIC_PENDSV_PRI;
+ *(portNVIC_SYSPRI2) |= portNVIC_SYSTICK_PRI;
+
+ /* Start the timer that generates the tick ISR. Interrupts are disabled
+ here already. */
+ prvSetupTimerInterrupt();
+
+ /* Initialise the critical nesting count ready for the first task. */
+ uxCriticalNesting = 0;
+
+ /* Start the first task. */
+ prvPortStartFirstTask();
+
+ /* Should not get here! */
+ return 0;
+}
+/*-----------------------------------------------------------*/
+
+void vPortEndScheduler( void )
+{
+ /* It is unlikely that the CM0 port will require this function as there
+ is nothing to return to. */
+}
+/*-----------------------------------------------------------*/
+
+void vPortYield( void )
+{
+ /* Set a PendSV to request a context switch. */
+ *( portNVIC_INT_CTRL ) = portNVIC_PENDSVSET;
+
+ /* Barriers are normally not required but do ensure the code is completely
+ within the specified behaviour for the architecture. */
+ __dsb( portSY_FULL_READ_WRITE );
+ __isb( portSY_FULL_READ_WRITE );
+}
+/*-----------------------------------------------------------*/
+
+void vPortEnterCritical( void )
+{
+ portDISABLE_INTERRUPTS();
+ uxCriticalNesting++;
+ __dsb( portSY_FULL_READ_WRITE );
+ __isb( portSY_FULL_READ_WRITE );
+}
+/*-----------------------------------------------------------*/
+
+void vPortExitCritical( void )
+{
+ uxCriticalNesting--;
+ if( uxCriticalNesting == 0 )
+ {
+ portENABLE_INTERRUPTS();
+ }
+}
+/*-----------------------------------------------------------*/
+
+__asm unsigned long ulSetInterruptMaskFromISR( void )
+{
+ mrs r0, PRIMASK
+ cpsid i
+ bx lr
+}
+/*-----------------------------------------------------------*/
+
+__asm void vClearInterruptMaskFromISR( unsigned long ulMask )
+{
+ msr PRIMASK, r0
+ bx lr
+}
+/*-----------------------------------------------------------*/
+
+__asm void xPortPendSVHandler( void )
+{
+ extern vTaskSwitchContext
+ extern pxCurrentTCB
+
+ PRESERVE8
+
+ mrs r0, psp
+
+ ldr r3, =pxCurrentTCB /* Get the location of the current TCB. */
+ ldr r2, [r3]
+
+ subs r0, #32 /* Make space for the remaining low registers. */
+ str r0, [r2] /* Save the new top of stack. */
+ stmia r0!, {r4-r7} /* Store the low registers that are not saved automatically. */
+ mov r4, r8 /* Store the high registers. */
+ mov r5, r9
+ mov r6, r10
+ mov r7, r11
+ stmia r0!, {r4-r7}
+
+ push {r3, r14}
+ cpsid i
+ bl vTaskSwitchContext
+ cpsie i
+ pop {r2, r3} /* lr goes in r3. r2 now holds tcb pointer. */
+
+ ldr r1, [r2]
+ ldr r0, [r1] /* The first item in pxCurrentTCB is the task top of stack. */
+ adds r0, #16 /* Move to the high registers. */
+ ldmia r0!, {r4-r7} /* Pop the high registers. */
+ mov r8, r4
+ mov r9, r5
+ mov r10, r6
+ mov r11, r7
+
+ msr psp, r0 /* Remember the new top of stack for the task. */
+
+ subs r0, #32 /* Go back for the low registers that are not automatically restored. */
+ ldmia r0!, {r4-r7} /* Pop low registers. */
+
+ bx r3
+ ALIGN
+}
+/*-----------------------------------------------------------*/
+
+void xPortSysTickHandler( void )
+{
+unsigned long ulPreviousMask;
+
+ ulPreviousMask = portSET_INTERRUPT_MASK_FROM_ISR();
+ {
+ /* Increment the RTOS tick. */
+ if( xTaskIncrementTick() != pdFALSE )
+ {
+ /* Pend a context switch. */
+ *(portNVIC_INT_CTRL) = portNVIC_PENDSVSET;
+ }
+ }
+ portCLEAR_INTERRUPT_MASK_FROM_ISR( ulPreviousMask );
+}
+/*-----------------------------------------------------------*/
+
+/*
+ * Setup the systick timer to generate the tick interrupts at the required
+ * frequency.
+ */
+void prvSetupTimerInterrupt( void )
+{
+ /* Configure SysTick to interrupt at the requested rate. */
+ *(portNVIC_SYSTICK_LOAD) = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;
+ *(portNVIC_SYSTICK_CTRL) = portNVIC_SYSTICK_CLK | portNVIC_SYSTICK_INT | portNVIC_SYSTICK_ENABLE;
+}
+/*-----------------------------------------------------------*/
+