1 /*
2 * FreeRTOS Kernel V11.1.0
3 * Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
4 *
5 * SPDX-License-Identifier: MIT
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy of
8 * this software and associated documentation files (the "Software"), to deal in
9 * the Software without restriction, including without limitation the rights to
10 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
11 * the Software, and to permit persons to whom the Software is furnished to do so,
12 * subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in all
15 * copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
19 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
20 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
21 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
22 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23 *
24 * https://www.FreeRTOS.org
25 * https://github.com/FreeRTOS
26 *
27 */
28
29 /*-----------------------------------------------------------
30 * Implementation of functions defined in portable.h for the ST STR71x ARM7
31 * port.
32 *----------------------------------------------------------*/
33
34 /* Library includes. */
35 #include "wdg.h"
36 #include "eic.h"
37
38 /* Standard includes. */
39 #include <stdlib.h>
40
41 /* Scheduler includes. */
42 #include "FreeRTOS.h"
43 #include "task.h"
44
45 /* Constants required to setup the initial stack. */
46 #define portINITIAL_SPSR ( ( StackType_t ) 0x1f ) /* System mode, ARM mode, interrupts enabled. */
47 #define portTHUMB_MODE_BIT ( ( StackType_t ) 0x20 )
48 #define portINSTRUCTION_SIZE ( ( StackType_t ) 4 )
49
50 /* Constants required to handle critical sections. */
51 #define portNO_CRITICAL_NESTING ( ( uint32_t ) 0 )
52
53 #define portMICROS_PER_SECOND 1000000
54
55 /*-----------------------------------------------------------*/
56
57 /* Setup the watchdog to generate the tick interrupts. */
58 static void prvSetupTimerInterrupt( void );
59
60 /* ulCriticalNesting will get set to zero when the first task starts. It
61 * cannot be initialised to 0 as this will cause interrupts to be enabled
62 * during the kernel initialisation process. */
63 uint32_t ulCriticalNesting = ( uint32_t ) 9999;
64
65 /* Tick interrupt routines for cooperative and preemptive operation
66 * respectively. The preemptive version is not defined as __irq as it is called
67 * from an asm wrapper function. */
68 __arm __irq void vPortNonPreemptiveTick( void );
69 void vPortPreemptiveTick( void );
70
71 /*-----------------------------------------------------------*/
72
73 /*
74 * Initialise the stack of a task to look exactly as if a call to
75 * portSAVE_CONTEXT had been called.
76 *
77 * See header file for description.
78 */
pxPortInitialiseStack(StackType_t * pxTopOfStack,TaskFunction_t pxCode,void * pvParameters)79 StackType_t * pxPortInitialiseStack( StackType_t * pxTopOfStack,
80 TaskFunction_t pxCode,
81 void * pvParameters )
82 {
83 StackType_t * pxOriginalTOS;
84
85 pxOriginalTOS = pxTopOfStack;
86
87 /* To ensure asserts in tasks.c don't fail, although in this case the assert
88 * is not really required. */
89 pxTopOfStack--;
90
91 /* Setup the initial stack of the task. The stack is set exactly as
92 * expected by the portRESTORE_CONTEXT() macro. */
93
94 /* First on the stack is the return address - which in this case is the
95 * start of the task. The offset is added to make the return address appear
96 * as it would within an IRQ ISR. */
97 *pxTopOfStack = ( StackType_t ) pxCode + portINSTRUCTION_SIZE;
98 pxTopOfStack--;
99
100 *pxTopOfStack = ( StackType_t ) 0xaaaaaaaa; /* R14 */
101 pxTopOfStack--;
102 *pxTopOfStack = ( StackType_t ) pxOriginalTOS; /* Stack used when task starts goes in R13. */
103 pxTopOfStack--;
104 *pxTopOfStack = ( StackType_t ) 0x12121212; /* R12 */
105 pxTopOfStack--;
106 *pxTopOfStack = ( StackType_t ) 0x11111111; /* R11 */
107 pxTopOfStack--;
108 *pxTopOfStack = ( StackType_t ) 0x10101010; /* R10 */
109 pxTopOfStack--;
110 *pxTopOfStack = ( StackType_t ) 0x09090909; /* R9 */
111 pxTopOfStack--;
112 *pxTopOfStack = ( StackType_t ) 0x08080808; /* R8 */
113 pxTopOfStack--;
114 *pxTopOfStack = ( StackType_t ) 0x07070707; /* R7 */
115 pxTopOfStack--;
116 *pxTopOfStack = ( StackType_t ) 0x06060606; /* R6 */
117 pxTopOfStack--;
118 *pxTopOfStack = ( StackType_t ) 0x05050505; /* R5 */
119 pxTopOfStack--;
120 *pxTopOfStack = ( StackType_t ) 0x04040404; /* R4 */
121 pxTopOfStack--;
122 *pxTopOfStack = ( StackType_t ) 0x03030303; /* R3 */
123 pxTopOfStack--;
124 *pxTopOfStack = ( StackType_t ) 0x02020202; /* R2 */
125 pxTopOfStack--;
126 *pxTopOfStack = ( StackType_t ) 0x01010101; /* R1 */
127 pxTopOfStack--;
128
129 /* When the task starts is will expect to find the function parameter in
130 * R0. */
131 *pxTopOfStack = ( StackType_t ) pvParameters; /* R0 */
132 pxTopOfStack--;
133
134 /* The status register is set for system mode, with interrupts enabled. */
135 *pxTopOfStack = ( StackType_t ) portINITIAL_SPSR;
136
137 if( ( ( uint32_t ) pxCode & 0x01UL ) != 0x00UL )
138 {
139 /* We want the task to start in thumb mode. */
140 *pxTopOfStack |= portTHUMB_MODE_BIT;
141 }
142
143 pxTopOfStack--;
144
145 /* Interrupt flags cannot always be stored on the stack and will
146 * instead be stored in a variable, which is then saved as part of the
147 * tasks context. */
148 *pxTopOfStack = portNO_CRITICAL_NESTING;
149
150 return pxTopOfStack;
151 }
152 /*-----------------------------------------------------------*/
153
xPortStartScheduler(void)154 BaseType_t xPortStartScheduler( void )
155 {
156 extern void vPortStartFirstTask( void );
157
158 /* Start the timer that generates the tick ISR. Interrupts are disabled
159 * here already. */
160 prvSetupTimerInterrupt();
161
162 /* Start the first task. */
163 vPortStartFirstTask();
164
165 /* Should not get here! */
166 return 0;
167 }
168 /*-----------------------------------------------------------*/
169
vPortEndScheduler(void)170 void vPortEndScheduler( void )
171 {
172 /* It is unlikely that the ARM port will require this function as there
173 * is nothing to return to. */
174 }
175 /*-----------------------------------------------------------*/
176
177 /* The cooperative scheduler requires a normal IRQ service routine to
178 * simply increment the system tick. */
vPortNonPreemptiveTick(void)179 __arm __irq void vPortNonPreemptiveTick( void )
180 {
181 /* Increment the tick count - which may wake some tasks but as the
182 * preemptive scheduler is not being used any woken task is not given
183 * processor time no matter what its priority. */
184 xTaskIncrementTick();
185
186 /* Clear the interrupt in the watchdog and EIC. */
187 WDG->SR = 0x0000;
188 portCLEAR_EIC();
189 }
190 /*-----------------------------------------------------------*/
191
192 /* This function is called from an asm wrapper, so does not require the __irq
193 * keyword. */
vPortPreemptiveTick(void)194 void vPortPreemptiveTick( void )
195 {
196 /* Increment the tick counter. */
197 if( xTaskIncrementTick() != pdFALSE )
198 {
199 /* Select a new task to execute. */
200 vTaskSwitchContext();
201 }
202
203 /* Clear the interrupt in the watchdog and EIC. */
204 WDG->SR = 0x0000;
205 portCLEAR_EIC();
206 }
207 /*-----------------------------------------------------------*/
208
prvSetupTimerInterrupt(void)209 static void prvSetupTimerInterrupt( void )
210 {
211 /* Set the watchdog up to generate a periodic tick. */
212 WDG_ECITConfig( DISABLE );
213 WDG_CntOnOffConfig( DISABLE );
214 WDG_PeriodValueConfig( portMICROS_PER_SECOND / configTICK_RATE_HZ );
215
216 /* Setup the tick interrupt in the EIC. */
217 EIC_IRQChannelPriorityConfig( WDG_IRQChannel, 1 );
218 EIC_IRQChannelConfig( WDG_IRQChannel, ENABLE );
219 EIC_IRQConfig( ENABLE );
220 WDG_ECITConfig( ENABLE );
221
222 /* Start the timer - interrupts are actually disabled at this point so
223 * it is safe to do this here. */
224 WDG_CntOnOffConfig( ENABLE );
225 }
226 /*-----------------------------------------------------------*/
227
vPortEnterCritical(void)228 __arm __interwork void vPortEnterCritical( void )
229 {
230 /* Disable interrupts first! */
231 __disable_interrupt();
232
233 /* Now that interrupts are disabled, ulCriticalNesting can be accessed
234 * directly. Increment ulCriticalNesting to keep a count of how many times
235 * portENTER_CRITICAL() has been called. */
236 ulCriticalNesting++;
237 }
238 /*-----------------------------------------------------------*/
239
vPortExitCritical(void)240 __arm __interwork void vPortExitCritical( void )
241 {
242 if( ulCriticalNesting > portNO_CRITICAL_NESTING )
243 {
244 /* Decrement the nesting count as we are leaving a critical section. */
245 ulCriticalNesting--;
246
247 /* If the nesting level has reached zero then interrupts should be
248 * re-enabled. */
249 if( ulCriticalNesting == portNO_CRITICAL_NESTING )
250 {
251 __enable_interrupt();
252 }
253 }
254 }
255 /*-----------------------------------------------------------*/
256
