1 /*
2 * FreeRTOS Kernel V10.6.2
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 STR75x ARM7
31 * port.
32 *----------------------------------------------------------*/
33
34 /* Library includes. */
35 #include "75x_tb.h"
36 #include "75x_eic.h"
37
38 /* Scheduler includes. */
39 #include "FreeRTOS.h"
40 #include "task.h"
41
42 /* Constants required to setup the initial stack. */
43 #define portINITIAL_SPSR ( ( StackType_t ) 0x3f ) /* System mode, THUMB mode, interrupts enabled. */
44 #define portINSTRUCTION_SIZE ( ( StackType_t ) 4 )
45
46 /* Constants required to handle critical sections. */
47 #define portNO_CRITICAL_NESTING ( ( uint32_t ) 0 )
48
49 /* Prescale used on the timer clock when calculating the tick period. */
50 #define portPRESCALE 20
51
52
53 /*-----------------------------------------------------------*/
54
55 /* Setup the TB to generate the tick interrupts. */
56 static void prvSetupTimerInterrupt( void );
57
58 /* ulCriticalNesting will get set to zero when the first task starts. It
59 cannot be initialised to 0 as this will cause interrupts to be enabled
60 during the kernel initialisation process. */
61 uint32_t ulCriticalNesting = ( uint32_t ) 9999;
62
63 /* Tick interrupt routines for preemptive operation. */
64 __arm void vPortPreemptiveTick( void );
65
66 /*-----------------------------------------------------------*/
67
68 /*
69 * Initialise the stack of a task to look exactly as if a call to
70 * portSAVE_CONTEXT had been called.
71 *
72 * See header file for description.
73 */
pxPortInitialiseStack(StackType_t * pxTopOfStack,TaskFunction_t pxCode,void * pvParameters)74 StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
75 {
76 StackType_t *pxOriginalTOS;
77
78 pxOriginalTOS = pxTopOfStack;
79
80 /* To ensure asserts in tasks.c don't fail, although in this case the assert
81 is not really required. */
82 pxTopOfStack--;
83
84 /* Setup the initial stack of the task. The stack is set exactly as
85 expected by the portRESTORE_CONTEXT() macro. */
86
87 /* First on the stack is the return address - which in this case is the
88 start of the task. The offset is added to make the return address appear
89 as it would within an IRQ ISR. */
90 *pxTopOfStack = ( StackType_t ) pxCode + portINSTRUCTION_SIZE;
91 pxTopOfStack--;
92
93 *pxTopOfStack = ( StackType_t ) 0xaaaaaaaa; /* R14 */
94 pxTopOfStack--;
95 *pxTopOfStack = ( StackType_t ) pxOriginalTOS; /* Stack used when task starts goes in R13. */
96 pxTopOfStack--;
97 *pxTopOfStack = ( StackType_t ) 0x12121212; /* R12 */
98 pxTopOfStack--;
99 *pxTopOfStack = ( StackType_t ) 0x11111111; /* R11 */
100 pxTopOfStack--;
101 *pxTopOfStack = ( StackType_t ) 0x10101010; /* R10 */
102 pxTopOfStack--;
103 *pxTopOfStack = ( StackType_t ) 0x09090909; /* R9 */
104 pxTopOfStack--;
105 *pxTopOfStack = ( StackType_t ) 0x08080808; /* R8 */
106 pxTopOfStack--;
107 *pxTopOfStack = ( StackType_t ) 0x07070707; /* R7 */
108 pxTopOfStack--;
109 *pxTopOfStack = ( StackType_t ) 0x06060606; /* R6 */
110 pxTopOfStack--;
111 *pxTopOfStack = ( StackType_t ) 0x05050505; /* R5 */
112 pxTopOfStack--;
113 *pxTopOfStack = ( StackType_t ) 0x04040404; /* R4 */
114 pxTopOfStack--;
115 *pxTopOfStack = ( StackType_t ) 0x03030303; /* R3 */
116 pxTopOfStack--;
117 *pxTopOfStack = ( StackType_t ) 0x02020202; /* R2 */
118 pxTopOfStack--;
119 *pxTopOfStack = ( StackType_t ) 0x01010101; /* R1 */
120 pxTopOfStack--;
121
122 /* When the task starts is will expect to find the function parameter in
123 R0. */
124 *pxTopOfStack = ( StackType_t ) pvParameters; /* R0 */
125 pxTopOfStack--;
126
127 /* The status register is set for system mode, with interrupts enabled. */
128 *pxTopOfStack = ( StackType_t ) portINITIAL_SPSR;
129 pxTopOfStack--;
130
131 /* Interrupt flags cannot always be stored on the stack and will
132 instead be stored in a variable, which is then saved as part of the
133 tasks context. */
134 *pxTopOfStack = portNO_CRITICAL_NESTING;
135
136 return pxTopOfStack;
137 }
138 /*-----------------------------------------------------------*/
139
xPortStartScheduler(void)140 BaseType_t xPortStartScheduler( void )
141 {
142 extern void vPortStartFirstTask( void );
143
144 /* Start the timer that generates the tick ISR. Interrupts are disabled
145 here already. */
146 prvSetupTimerInterrupt();
147
148 /* Start the first task. */
149 vPortStartFirstTask();
150
151 /* Should not get here! */
152 return 0;
153 }
154 /*-----------------------------------------------------------*/
155
vPortEndScheduler(void)156 void vPortEndScheduler( void )
157 {
158 /* It is unlikely that the ARM port will require this function as there
159 is nothing to return to. */
160 }
161 /*-----------------------------------------------------------*/
162
vPortPreemptiveTick(void)163 __arm void vPortPreemptiveTick( void )
164 {
165 /* Increment the tick counter. */
166 if( xTaskIncrementTick() != pdFALSE )
167 {
168 /* Select a new task to execute. */
169 vTaskSwitchContext();
170 }
171
172 TB_ClearITPendingBit( TB_IT_Update );
173 }
174 /*-----------------------------------------------------------*/
175
prvSetupTimerInterrupt(void)176 static void prvSetupTimerInterrupt( void )
177 {
178 EIC_IRQInitTypeDef EIC_IRQInitStructure;
179 TB_InitTypeDef TB_InitStructure;
180
181 /* Setup the EIC for the TB. */
182 EIC_IRQInitStructure.EIC_IRQChannelCmd = ENABLE;
183 EIC_IRQInitStructure.EIC_IRQChannel = TB_IRQChannel;
184 EIC_IRQInitStructure.EIC_IRQChannelPriority = 1;
185 EIC_IRQInit(&EIC_IRQInitStructure);
186
187 /* Setup the TB for the generation of the tick interrupt. */
188 TB_InitStructure.TB_Mode = TB_Mode_Timing;
189 TB_InitStructure.TB_CounterMode = TB_CounterMode_Down;
190 TB_InitStructure.TB_Prescaler = portPRESCALE - 1;
191 TB_InitStructure.TB_AutoReload = ( ( configCPU_CLOCK_HZ / portPRESCALE ) / configTICK_RATE_HZ );
192 TB_Init(&TB_InitStructure);
193
194 /* Enable TB Update interrupt */
195 TB_ITConfig(TB_IT_Update, ENABLE);
196
197 /* Clear TB Update interrupt pending bit */
198 TB_ClearITPendingBit(TB_IT_Update);
199
200 /* Enable TB */
201 TB_Cmd(ENABLE);
202 }
203 /*-----------------------------------------------------------*/
204
vPortEnterCritical(void)205 __arm __interwork void vPortEnterCritical( void )
206 {
207 /* Disable interrupts first! */
208 __disable_interrupt();
209
210 /* Now interrupts are disabled ulCriticalNesting can be accessed
211 directly. Increment ulCriticalNesting to keep a count of how many times
212 portENTER_CRITICAL() has been called. */
213 ulCriticalNesting++;
214 }
215 /*-----------------------------------------------------------*/
216
vPortExitCritical(void)217 __arm __interwork void vPortExitCritical( void )
218 {
219 if( ulCriticalNesting > portNO_CRITICAL_NESTING )
220 {
221 /* Decrement the nesting count as we are leaving a critical section. */
222 ulCriticalNesting--;
223
224 /* If the nesting level has reached zero then interrupts should be
225 re-enabled. */
226 if( ulCriticalNesting == portNO_CRITICAL_NESTING )
227 {
228 __enable_interrupt();
229 }
230 }
231 }
232 /*-----------------------------------------------------------*/
233
