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 /* GCC/HCS12 port by Jefferson L Smith, 2005 */
30
31 /* Scheduler includes. */
32 #include "FreeRTOS.h"
33 #include "task.h"
34
35 /* Port includes */
36 #include <sys/ports_def.h>
37
38 /*-----------------------------------------------------------
39 * Implementation of functions defined in portable.h for the HCS12 port.
40 *----------------------------------------------------------*/
41
42
43 /*
44 * Configure a timer to generate the RTOS tick at the frequency specified
45 * within FreeRTOSConfig.h.
46 */
47 static void prvSetupTimerInterrupt( void );
48
49 /* NOTE: Interrupt service routines must be in non-banked memory - as does the
50 * scheduler startup function. */
51 #define ATTR_NEAR __attribute__( ( near ) )
52
53 /* Manual context switch function. This is the SWI ISR. */
54 /* __attribute__((interrupt)) */
55 void ATTR_NEAR vPortYield( void );
56
57 /* Tick context switch function. This is the timer ISR. */
58 /* __attribute__((interrupt)) */
59 void ATTR_NEAR vPortTickInterrupt( void );
60
61 /* Function in non-banked memory which actually switches to first task. */
62 BaseType_t ATTR_NEAR xStartSchedulerNear( void );
63
64 /* Calls to portENTER_CRITICAL() can be nested. When they are nested the
65 * critical section should not be left (i.e. interrupts should not be re-enabled)
66 * until the nesting depth reaches 0. This variable simply tracks the nesting
67 * depth. Each task maintains it's own critical nesting depth variable so
68 * uxCriticalNesting is saved and restored from the task stack during a context
69 * switch. */
70 volatile UBaseType_t uxCriticalNesting = 0x80; /* un-initialized */
71
72 /*-----------------------------------------------------------*/
73
74 /*
75 * See header file for description.
76 */
pxPortInitialiseStack(StackType_t * pxTopOfStack,TaskFunction_t pxCode,void * pvParameters)77 StackType_t * pxPortInitialiseStack( StackType_t * pxTopOfStack,
78 TaskFunction_t pxCode,
79 void * pvParameters )
80 {
81 /* Setup the initial stack of the task. The stack is set exactly as
82 * expected by the portRESTORE_CONTEXT() macro. In this case the stack as
83 * expected by the HCS12 RTI instruction. */
84
85
86 /* The address of the task function is placed in the stack byte at a time. */
87 *pxTopOfStack = ( StackType_t ) *( ( ( StackType_t * ) ( &pxCode ) ) + 1 );
88 *--pxTopOfStack = ( StackType_t ) *( ( ( StackType_t * ) ( &pxCode ) ) + 0 );
89
90 /* Next are all the registers that form part of the task context. */
91
92 /* Y register */
93 *--pxTopOfStack = ( StackType_t ) 0xff;
94 *--pxTopOfStack = ( StackType_t ) 0xee;
95
96 /* X register */
97 *--pxTopOfStack = ( StackType_t ) 0xdd;
98 *--pxTopOfStack = ( StackType_t ) 0xcc;
99
100 /* A register contains parameter high byte. */
101 *--pxTopOfStack = ( StackType_t ) *( ( ( StackType_t * ) ( &pvParameters ) ) + 0 );
102
103 /* B register contains parameter low byte. */
104 *--pxTopOfStack = ( StackType_t ) *( ( ( StackType_t * ) ( &pvParameters ) ) + 1 );
105
106 /* CCR: Note that when the task starts interrupts will be enabled since
107 * "I" bit of CCR is cleared */
108 *--pxTopOfStack = ( StackType_t ) 0x80; /* keeps Stop disabled (MCU default) */
109
110 /* tmp softregs used by GCC. Values right now don't matter. */
111 __asm( "\n\
112 movw _.frame, 2,-%0 \n\
113 movw _.tmp, 2,-%0 \n\
114 movw _.z, 2,-%0 \n\
115 movw _.xy, 2,-%0 \n\
116 ;movw _.d2, 2,-%0 \n\
117 ;movw _.d1, 2,-%0 \n\
118 " : "=A" ( pxTopOfStack ) : "0" ( pxTopOfStack ) );
119
120 #ifdef BANKED_MODEL
121 /* The page of the task. */
122 *--pxTopOfStack = 0x30; /* can only directly start in PPAGE 0x30 */
123 #endif
124
125 /* The critical nesting depth is initialised with 0 (meaning not in
126 * a critical section). */
127 *--pxTopOfStack = ( StackType_t ) 0x00;
128
129
130 return pxTopOfStack;
131 }
132 /*-----------------------------------------------------------*/
133
vPortEndScheduler(void)134 void vPortEndScheduler( void )
135 {
136 /* It is unlikely that the HCS12 port will get stopped. */
137 }
138 /*-----------------------------------------------------------*/
139
prvSetupTimerInterrupt(void)140 static void prvSetupTimerInterrupt( void )
141 {
142 /* Enable hardware RTI timer */
143 /* Ignores configTICK_RATE_HZ */
144 RTICTL = 0x50; /* 16 MHz xtal: 976.56 Hz, 1024mS */
145 CRGINT |= 0x80; /* RTIE */
146 }
147 /*-----------------------------------------------------------*/
148
xPortStartScheduler(void)149 BaseType_t xPortStartScheduler( void )
150 {
151 /* xPortStartScheduler() does not start the scheduler directly because
152 * the header file containing the xPortStartScheduler() prototype is part
153 * of the common kernel code, and therefore cannot use the CODE_SEG pragma.
154 * Instead it simply calls the locally defined xNearStartScheduler() -
155 * which does use the CODE_SEG pragma. */
156
157 int16_t register d;
158
159 __asm( "jmp xStartSchedulerNear ; will never return" : "=d" ( d ) );
160 return d;
161 }
162 /*-----------------------------------------------------------*/
163
xStartSchedulerNear(void)164 BaseType_t xStartSchedulerNear( void )
165 {
166 /* Configure the timer that will generate the RTOS tick. Interrupts are
167 * disabled when this function is called. */
168 prvSetupTimerInterrupt();
169
170 /* Restore the context of the first task. */
171 portRESTORE_CONTEXT();
172
173 portISR_TAIL();
174
175 /* Should not get here! */
176 return pdFALSE;
177 }
178 /*-----------------------------------------------------------*/
179
180 /*
181 * Context switch functions. These are interrupt service routines.
182 */
183
184 /*
185 * Manual context switch forced by calling portYIELD(). This is the SWI
186 * handler.
187 */
vPortYield(void)188 void vPortYield( void )
189 {
190 portISR_HEAD();
191
192 /* NOTE: This is the trap routine (swi) although not defined as a trap.
193 * It will fill the stack the same way as an ISR in order to mix preemtion
194 * and cooperative yield. */
195
196 portSAVE_CONTEXT();
197 vTaskSwitchContext();
198 portRESTORE_CONTEXT();
199
200 portISR_TAIL();
201 }
202 /*-----------------------------------------------------------*/
203
204 /*
205 * RTOS tick interrupt service routine. If the cooperative scheduler is
206 * being used then this simply increments the tick count. If the
207 * preemptive scheduler is being used a context switch can occur.
208 */
vPortTickInterrupt(void)209 void vPortTickInterrupt( void )
210 {
211 portISR_HEAD();
212
213 /* Clear tick timer flag */
214 CRGFLG = 0x80;
215
216 #if configUSE_PREEMPTION == 1
217 {
218 /* A context switch might happen so save the context. */
219 portSAVE_CONTEXT();
220
221 /* Increment the tick ... */
222 if( xTaskIncrementTick() != pdFALSE )
223 {
224 /* A context switch is necessary. */
225 vTaskSwitchContext();
226 }
227
228 /* Restore the context of a task - which may be a different task
229 * to that interrupted. */
230 portRESTORE_CONTEXT();
231 }
232 #else /* if configUSE_PREEMPTION == 1 */
233 {
234 xTaskIncrementTick();
235 }
236 #endif /* if configUSE_PREEMPTION == 1 */
237
238 portISR_TAIL();
239 }
240
