1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
|
/*
FreeRTOS.org V5.3.0 - 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.
**NOTE** The 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. Alternative commercial
license and support terms are also available upon request. See the
licensing section of http://www.FreeRTOS.org for full details.
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.
***************************************************************************
* *
* 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.
*/
/*-----------------------------------------------------------
* Implementation of functions defined in portable.h for the MicroBlaze port.
*----------------------------------------------------------*/
/* Scheduler includes. */
#include "FreeRTOS.h"
#include "task.h"
/* Standard includes. */
#include <string.h>
/* hardware/software platform specific defines */
#define DISABLE_C_PROTOTYPES
#include <devices.h>
/* Tasks are started with interrupts enabled. */
#define portINITIAL_INTERRUPT_ENABLE ( ( portSTACK_TYPE ) INTERRUPT_GLOBAL_ENABLE )
/* Tasks are started with a critical section nesting of 0 - however prior
to the scheduler being commenced we don't want the critical nesting level
to reach zero, so it is initialised to a high value. */
#define portINITIAL_NESTING_VALUE ( 0xff )
/* The stack used by the ISR is filled with a known value to assist in
debugging. */
#define portISR_STACK_FILL_VALUE 0x55555555
/* Counts the nesting depth of calls to portENTER_CRITICAL(). Each task
maintains it's own count, so this variable is saved as part of the task
context. */
volatile unsigned portBASE_TYPE uxCriticalNesting = portINITIAL_NESTING_VALUE;
/* To limit the amount of stack required by each task, this port uses a
separate stack for interrupts. */
unsigned portLONG *pulISRStack;
/*-----------------------------------------------------------*/
/*
* Sets up the periodic ISR used for the RTOS tick. This uses timer 0, but
* could have alternatively used the watchdog timer or timer 1.
*/
static void prvSetupTimerInterrupt( void );
/*-----------------------------------------------------------*/
/*
* Initialise the stack of a task to look exactly as if a call to
* portSAVE_CONTEXT had been made.
*
* See the header file portable.h.
*/
portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
{
/* Function call parameters. */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) pvParameters;
/* Place initial PC (task entry point) */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) pxCode; /* PC */
/* Place initial value for INTERRUPT global ENABLE */
pxTopOfStack--;
*pxTopOfStack = portINITIAL_INTERRUPT_ENABLE; /* interrupt state (global enable) */
/* Stack an initial value for the critical section nesting. This
is initialised to zero as tasks are started with interrupts enabled. */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x00;
/* Place an initial value for all temporary registers mapped to mem[0..16] by gcc */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x11111111; /* mem[0] */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x22222222; /* mem[4] */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x33333333; /* mem[8] */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x44444444; /* mem[12] */
/* Return a pointer to the top of the stack we have generated so this can
be stored in the task control block for the task. */
return pxTopOfStack;
}
/*-----------------------------------------------------------*/
portBASE_TYPE xPortStartScheduler( void )
{
extern void ( __FreeRTOS_interrupt_handler )( void );
extern void ( vStartFirstTask )( void );
/* Setup the FreeRTOS interrupt handler */
*(volatile unsigned *) INTERRUPT_VECTOR = (unsigned) __FreeRTOS_interrupt_handler;
/* Setup the hardware to generate the tick. Interrupts are disabled when
this function is called. */
prvSetupTimerInterrupt();
/* Allocate the stack to be used by the interrupt handler. */
pulISRStack = ( unsigned portLONG * ) pvPortMalloc( configMINIMAL_STACK_SIZE * sizeof( portSTACK_TYPE ) );
/* Restore the context of the first task that is going to run. */
if( pulISRStack != NULL )
{
/* Fill the ISR stack with a known value to facilitate debugging. */
memset( pulISRStack, portISR_STACK_FILL_VALUE, configMINIMAL_STACK_SIZE * sizeof( portSTACK_TYPE ) );
pulISRStack += ( configMINIMAL_STACK_SIZE - 1 );
/* Kick off the first task. */
vStartFirstTask();
}
/* Should not get here as the tasks are now running! */
return pdFALSE;
}
/*-----------------------------------------------------------*/
void vPortEndScheduler( void )
{
/* Not implemented. */
}
/*-----------------------------------------------------------*/
/*
* Manual context switch called by portYIELD or taskYIELD.
*/
void vPortYield( void )
{
extern void VPortYieldASM( void );
/* Perform the context switch in a critical section to assure it is
not interrupted by the tick ISR. It is not a problem to do this as
each task maintains it's own interrupt status. */
portENTER_CRITICAL();
/* Jump directly to the yield function to ensure there is no
compiler generated prologue code. */
asm volatile ( "im VPortYieldASM \n\t" \
"call \n\t" );
portEXIT_CRITICAL();
}
/*-----------------------------------------------------------*/
/*
* Hardware initialisation to generate the RTOS tick.
*/
static void prvSetupTimerInterrupt( void )
{
const unsigned portLONG ulCounterValue = configCPU_CLOCK_HZ / configTICK_RATE_HZ;
/* Initialize and start timer1 counter */
*(volatile unsigned *) TIMER1_PORT = ulCounterValue;
*(volatile unsigned *) TIMERS_CONTROL = TIMER1_ENABLE;
/* Enable timer1 interrupt while maintaining other bit states
but disable global enable */
*(volatile unsigned *) INTERRUPT_ENABLE &= ~INTERRUPT_GLOBAL_ENABLE;
*(volatile unsigned *) INTERRUPT_ENABLE |= INTERRUPT_TIMER1;
}
/*-----------------------------------------------------------*/
/*
* The interrupt handler placed in the interrupt vector when the scheduler is
* started. The task context has already been saved when this is called.
* This handler determines the interrupt source and calls the relevant
* peripheral handler.
*/
void vTaskISRHandler( void )
{
void vTickISR(void);
unsigned int_status = *(volatile unsigned *) INTERRUPT_STATUS;
if(int_status & INTERRUPT_TIMER1) vTickISR();
}
/*-----------------------------------------------------------*/
/*
* Handler for the timer interrupt.
*/
void vTickISR( void )
{
/* Increment the RTOS tick - this might cause a task to unblock. */
vTaskIncrementTick();
/* Clear the timer interrupt */
/* ... in this platform, timer interrupt is cleared automatically */
/* If we are using the preemptive scheduler then we also need to determine
if this tick should cause a context switch. */
#if configUSE_PREEMPTION == 1
vTaskSwitchContext();
#endif
}
/*-----------------------------------------------------------*/
void zpu_disable_interrupts(void)
{
*(volatile unsigned *) INTERRUPT_ENABLE &= ~INTERRUPT_GLOBAL_ENABLE;
}
void zpu_enable_interrupts(void)
{
*(volatile unsigned *) INTERRUPT_ENABLE |= INTERRUPT_GLOBAL_ENABLE;
}
/*-----------------------------------------------------------*/
void zpu_enter_critical(void)
{
portDISABLE_INTERRUPTS();
uxCriticalNesting++;
}
void zpu_exit_critical(void)
{
if( --uxCriticalNesting == 0 )
{
portENABLE_INTERRUPTS();
}
}
|
