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 RX200 port.
31 *----------------------------------------------------------*/
32
33 /* Scheduler includes. */
34 #include "FreeRTOS.h"
35 #include "task.h"
36
37 /* Library includes. */
38 #include "string.h"
39
40 /* Hardware specifics. */
41 #include "iodefine.h"
42
43 /*-----------------------------------------------------------*/
44
45 /* Tasks should start with interrupts enabled and in Supervisor mode, therefore
46 PSW is set with U and I set, and PM and IPL clear. */
47 #define portINITIAL_PSW ( ( StackType_t ) 0x00030000 )
48
49 /*-----------------------------------------------------------*/
50
51 /* The following lines are to ensure vSoftwareInterruptEntry can be referenced,
52 and therefore installed in the vector table, when the FreeRTOS code is built
53 as a library. */
54 extern BaseType_t vSoftwareInterruptEntry;
55 const BaseType_t * p_vSoftwareInterruptEntry = &vSoftwareInterruptEntry;
56
57 /*-----------------------------------------------------------*/
58
59 /*
60 * Function to start the first task executing - written in asm code as direct
61 * access to registers is required.
62 */
63 static void prvStartFirstTask( void );
64
65 /*
66 * Software interrupt handler. Performs the actual context switch (saving and
67 * restoring of registers). Written in asm code as direct register access is
68 * required.
69 */
70 static void prvYieldHandler( void );
71
72 /*
73 * The entry point for the software interrupt handler. This is the function
74 * that calls the inline asm function prvYieldHandler(). It is installed in
75 * the vector table, but the code that installs it is in prvYieldHandler rather
76 * than using a #pragma.
77 */
78 void vSoftwareInterruptISR( void );
79
80 /*-----------------------------------------------------------*/
81
82 /* This is accessed by the inline assembler functions so is file scope for
83 convenience. */
84 extern void *pxCurrentTCB;
85 extern void vTaskSwitchContext( void );
86
87 /*-----------------------------------------------------------*/
88
89 /*
90 * See header file for description.
91 */
pxPortInitialiseStack(StackType_t * pxTopOfStack,TaskFunction_t pxCode,void * pvParameters)92 StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
93 {
94 /* Offset to end up on 8 byte boundary. */
95 pxTopOfStack--;
96
97 /* R0 is not included as it is the stack pointer. */
98 *pxTopOfStack = 0x00;
99 pxTopOfStack--;
100 *pxTopOfStack = 0x00;
101 pxTopOfStack--;
102 *pxTopOfStack = portINITIAL_PSW;
103 pxTopOfStack--;
104 *pxTopOfStack = ( StackType_t ) pxCode;
105
106 /* When debugging it can be useful if every register is set to a known
107 value. Otherwise code space can be saved by just setting the registers
108 that need to be set. */
109 #ifdef USE_FULL_REGISTER_INITIALISATION
110 {
111 pxTopOfStack--;
112 *pxTopOfStack = 0x12345678; /* r15. */
113 pxTopOfStack--;
114 *pxTopOfStack = 0xaaaabbbb;
115 pxTopOfStack--;
116 *pxTopOfStack = 0xdddddddd;
117 pxTopOfStack--;
118 *pxTopOfStack = 0xcccccccc;
119 pxTopOfStack--;
120 *pxTopOfStack = 0xbbbbbbbb;
121 pxTopOfStack--;
122 *pxTopOfStack = 0xaaaaaaaa;
123 pxTopOfStack--;
124 *pxTopOfStack = 0x99999999;
125 pxTopOfStack--;
126 *pxTopOfStack = 0x88888888;
127 pxTopOfStack--;
128 *pxTopOfStack = 0x77777777;
129 pxTopOfStack--;
130 *pxTopOfStack = 0x66666666;
131 pxTopOfStack--;
132 *pxTopOfStack = 0x55555555;
133 pxTopOfStack--;
134 *pxTopOfStack = 0x44444444;
135 pxTopOfStack--;
136 *pxTopOfStack = 0x33333333;
137 pxTopOfStack--;
138 *pxTopOfStack = 0x22222222;
139 pxTopOfStack--;
140 }
141 #else
142 {
143 pxTopOfStack -= 15;
144 }
145 #endif
146
147 *pxTopOfStack = ( StackType_t ) pvParameters; /* R1 */
148 pxTopOfStack--;
149 *pxTopOfStack = 0x12345678; /* Accumulator. */
150 pxTopOfStack--;
151 *pxTopOfStack = 0x87654321; /* Accumulator. */
152
153 return pxTopOfStack;
154 }
155 /*-----------------------------------------------------------*/
156
xPortStartScheduler(void)157 BaseType_t xPortStartScheduler( void )
158 {
159 extern void vApplicationSetupTimerInterrupt( void );
160
161 /* Use pxCurrentTCB just so it does not get optimised away. */
162 if( pxCurrentTCB != NULL )
163 {
164 /* Call an application function to set up the timer that will generate the
165 tick interrupt. This way the application can decide which peripheral to
166 use. A demo application is provided to show a suitable example. */
167 vApplicationSetupTimerInterrupt();
168
169 /* Enable the software interrupt. */
170 _IEN( _ICU_SWINT ) = 1;
171
172 /* Ensure the software interrupt is clear. */
173 _IR( _ICU_SWINT ) = 0;
174
175 /* Ensure the software interrupt is set to the kernel priority. */
176 _IPR( _ICU_SWINT ) = configKERNEL_INTERRUPT_PRIORITY;
177
178 /* Start the first task. */
179 prvStartFirstTask();
180 }
181
182 /* Just to make sure the function is not optimised away. */
183 ( void ) vSoftwareInterruptISR();
184
185 /* Should not get here. */
186 return pdFAIL;
187 }
188 /*-----------------------------------------------------------*/
189
190 #pragma inline_asm prvStartFirstTask
prvStartFirstTask(void)191 static void prvStartFirstTask( void )
192 {
193 /* When starting the scheduler there is nothing that needs moving to the
194 interrupt stack because the function is not called from an interrupt.
195 Just ensure the current stack is the user stack. */
196 SETPSW U
197
198 /* Obtain the location of the stack associated with which ever task
199 pxCurrentTCB is currently pointing to. */
200 MOV.L #_pxCurrentTCB, R15
201 MOV.L [R15], R15
202 MOV.L [R15], R0
203
204 /* Restore the registers from the stack of the task pointed to by
205 pxCurrentTCB. */
206 POP R15
207 MVTACLO R15 /* Accumulator low 32 bits. */
208 POP R15
209 MVTACHI R15 /* Accumulator high 32 bits. */
210 POPM R1-R15 /* R1 to R15 - R0 is not included as it is the SP. */
211 RTE /* This pops the remaining registers. */
212 NOP
213 NOP
214 }
215 /*-----------------------------------------------------------*/
216
217 #pragma interrupt ( vTickISR( vect = _VECT( configTICK_VECTOR ), enable ) )
vTickISR(void)218 void vTickISR( void )
219 {
220 /* Increment the tick, and perform any processing the new tick value
221 necessitates. */
222 set_ipl( configMAX_SYSCALL_INTERRUPT_PRIORITY );
223 {
224 if( xTaskIncrementTick() != pdFALSE )
225 {
226 taskYIELD();
227 }
228 }
229 set_ipl( configKERNEL_INTERRUPT_PRIORITY );
230 }
231 /*-----------------------------------------------------------*/
232
vSoftwareInterruptISR(void)233 void vSoftwareInterruptISR( void )
234 {
235 prvYieldHandler();
236 }
237 /*-----------------------------------------------------------*/
238
239 #pragma inline_asm prvYieldHandler
prvYieldHandler(void)240 static void prvYieldHandler( void )
241 {
242 /* Re-enable interrupts. */
243 SETPSW I
244
245 /* Move the data that was automatically pushed onto the interrupt stack when
246 the interrupt occurred from the interrupt stack to the user stack.
247
248 R15 is saved before it is clobbered. */
249 PUSH.L R15
250
251 /* Read the user stack pointer. */
252 MVFC USP, R15
253
254 /* Move the address down to the data being moved. */
255 SUB #12, R15
256 MVTC R15, USP
257
258 /* Copy the data across. */
259 MOV.L [ R0 ], [ R15 ] ; R15
260 MOV.L 4[ R0 ], 4[ R15 ] ; PC
261 MOV.L 8[ R0 ], 8[ R15 ] ; PSW
262
263 /* Move the interrupt stack pointer to its new correct position. */
264 ADD #12, R0
265
266 /* All the rest of the registers are saved directly to the user stack. */
267 SETPSW U
268
269 /* Save the rest of the general registers (R15 has been saved already). */
270 PUSHM R1-R14
271
272 /* Save the accumulator. */
273 MVFACHI R15
274 PUSH.L R15
275 MVFACMI R15 ; Middle order word.
276 SHLL #16, R15 ; Shifted left as it is restored to the low order word.
277 PUSH.L R15
278
279 /* Save the stack pointer to the TCB. */
280 MOV.L #_pxCurrentTCB, R15
281 MOV.L [ R15 ], R15
282 MOV.L R0, [ R15 ]
283
284 /* Ensure the interrupt mask is set to the syscall priority while the kernel
285 structures are being accessed. */
286 MVTIPL #configMAX_SYSCALL_INTERRUPT_PRIORITY
287
288 /* Select the next task to run. */
289 BSR.A _vTaskSwitchContext
290
291 /* Reset the interrupt mask as no more data structure access is required. */
292 MVTIPL #configKERNEL_INTERRUPT_PRIORITY
293
294 /* Load the stack pointer of the task that is now selected as the Running
295 state task from its TCB. */
296 MOV.L #_pxCurrentTCB,R15
297 MOV.L [ R15 ], R15
298 MOV.L [ R15 ], R0
299
300 /* Restore the context of the new task. The PSW (Program Status Word) and
301 PC will be popped by the RTE instruction. */
302 POP R15
303 MVTACLO R15
304 POP R15
305 MVTACHI R15
306 POPM R1-R15
307 RTE
308 NOP
309 NOP
310 }
311 /*-----------------------------------------------------------*/
312
vPortEndScheduler(void)313 void vPortEndScheduler( void )
314 {
315 /* Not implemented in ports where there is nothing to return to.
316 Artificially force an assert. */
317 configASSERT( pxCurrentTCB == NULL );
318
319 /* The following line is just to prevent the symbol getting optimised away. */
320 ( void ) vTaskSwitchContext();
321 }
322 /*-----------------------------------------------------------*/
323
