1 /*
2 * FreeRTOS Kernel <DEVELOPMENT BRANCH>
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 /* Scheduler includes. */
30 #include "FreeRTOS.h"
31 #include "task.h"
32
33 /* Hardware includes. */
34 #include "msp430.h"
35
36 /*-----------------------------------------------------------
37 * Implementation of functions defined in portable.h for the MSP430X port.
38 *----------------------------------------------------------*/
39
40 /* Constants required for hardware setup. The tick ISR runs off the ACLK,
41 * not the MCLK. */
42 #define portACLK_FREQUENCY_HZ ( ( TickType_t ) 32768 )
43 #define portINITIAL_CRITICAL_NESTING ( ( uint16_t ) 10 )
44 #define portFLAGS_INT_ENABLED ( ( StackType_t ) 0x08 )
45
46 /* We require the address of the pxCurrentTCB variable, but don't want to know
47 * any details of its type. */
48 typedef void TCB_t;
49 extern volatile TCB_t * volatile pxCurrentTCB;
50
51 /* Each task maintains a count of the critical section nesting depth. Each
52 * time a critical section is entered the count is incremented. Each time a
53 * critical section is exited the count is decremented - with interrupts only
54 * being re-enabled if the count is zero.
55 *
56 * usCriticalNesting will get set to zero when the scheduler starts, but must
57 * not be initialised to zero as this will cause problems during the startup
58 * sequence. */
59 volatile uint16_t usCriticalNesting = portINITIAL_CRITICAL_NESTING;
60 /*-----------------------------------------------------------*/
61
62
63 /*
64 * Sets up the periodic ISR used for the RTOS tick. This uses timer 0, but
65 * could have alternatively used the watchdog timer or timer 1.
66 */
67 void vPortSetupTimerInterrupt( void );
68 /*-----------------------------------------------------------*/
69
70 /*
71 * Initialise the stack of a task to look exactly as if a call to
72 * portSAVE_CONTEXT had been called.
73 *
74 * See the header file portable.h.
75 */
pxPortInitialiseStack(StackType_t * pxTopOfStack,TaskFunction_t pxCode,void * pvParameters)76 StackType_t * pxPortInitialiseStack( StackType_t * pxTopOfStack,
77 TaskFunction_t pxCode,
78 void * pvParameters )
79 {
80 uint16_t * pusTopOfStack;
81 uint32_t * pulTopOfStack;
82
83 /*
84 * Place a few bytes of known values on the bottom of the stack.
85 * This is just useful for debugging and can be included if required.
86 *
87 * pxTopOfStack = ( StackType_t ) 0x1111;
88 * pxTopOfStack--;
89 * pxTopOfStack = ( StackType_t ) 0x2222;
90 * pxTopOfStack--;
91 * pxTopOfStack = ( StackType_t ) 0x3333;
92 */
93
94 /* StackType_t is either 16 bits or 32 bits depending on the data model.
95 * Some stacked items do not change size depending on the data model so have
96 * to be explicitly cast to the correct size so this function will work
97 * whichever data model is being used. */
98 if( sizeof( StackType_t ) == sizeof( uint16_t ) )
99 {
100 /* Make room for a 20 bit value stored as a 32 bit value. */
101 pusTopOfStack = ( uint16_t * ) pxTopOfStack;
102 pusTopOfStack--;
103 pulTopOfStack = ( uint32_t * ) pusTopOfStack;
104 }
105 else
106 {
107 pulTopOfStack = ( uint32_t * ) pxTopOfStack;
108 }
109
110 *pulTopOfStack = ( uint32_t ) pxCode;
111
112 pusTopOfStack = ( uint16_t * ) pulTopOfStack;
113 pusTopOfStack--;
114 *pusTopOfStack = portFLAGS_INT_ENABLED;
115 pusTopOfStack -= ( sizeof( StackType_t ) / 2 );
116
117 /* From here on the size of stacked items depends on the memory model. */
118 pxTopOfStack = ( StackType_t * ) pusTopOfStack;
119
120 /* Next the general purpose registers. */
121 #ifdef PRELOAD_REGISTER_VALUES
122 *pxTopOfStack = ( StackType_t ) 0xffff;
123 pxTopOfStack--;
124 *pxTopOfStack = ( StackType_t ) 0xeeee;
125 pxTopOfStack--;
126 *pxTopOfStack = ( StackType_t ) 0xdddd;
127 pxTopOfStack--;
128 *pxTopOfStack = ( StackType_t ) pvParameters;
129 pxTopOfStack--;
130 *pxTopOfStack = ( StackType_t ) 0xbbbb;
131 pxTopOfStack--;
132 *pxTopOfStack = ( StackType_t ) 0xaaaa;
133 pxTopOfStack--;
134 *pxTopOfStack = ( StackType_t ) 0x9999;
135 pxTopOfStack--;
136 *pxTopOfStack = ( StackType_t ) 0x8888;
137 pxTopOfStack--;
138 *pxTopOfStack = ( StackType_t ) 0x5555;
139 pxTopOfStack--;
140 *pxTopOfStack = ( StackType_t ) 0x6666;
141 pxTopOfStack--;
142 *pxTopOfStack = ( StackType_t ) 0x5555;
143 pxTopOfStack--;
144 *pxTopOfStack = ( StackType_t ) 0x4444;
145 pxTopOfStack--;
146 #else /* ifdef PRELOAD_REGISTER_VALUES */
147 pxTopOfStack -= 3;
148 *pxTopOfStack = ( StackType_t ) pvParameters;
149 pxTopOfStack -= 9;
150 #endif /* ifdef PRELOAD_REGISTER_VALUES */
151
152
153 /* A variable is used to keep track of the critical section nesting.
154 * This variable has to be stored as part of the task context and is
155 * initially set to zero. */
156 *pxTopOfStack = ( StackType_t ) portNO_CRITICAL_SECTION_NESTING;
157
158 /* Return a pointer to the top of the stack we have generated so this can
159 * be stored in the task control block for the task. */
160 return pxTopOfStack;
161 }
162 /*-----------------------------------------------------------*/
163
vPortEndScheduler(void)164 void vPortEndScheduler( void )
165 {
166 /* It is unlikely that the MSP430 port will get stopped. If required simply
167 * disable the tick interrupt here. */
168 }
169 /*-----------------------------------------------------------*/
170
171 /*
172 * Hardware initialisation to generate the RTOS tick.
173 */
vPortSetupTimerInterrupt(void)174 void vPortSetupTimerInterrupt( void )
175 {
176 vApplicationSetupTimerInterrupt();
177 }
178 /*-----------------------------------------------------------*/
179
180 #pragma vector=configTICK_VECTOR
vTickISREntry(void)181 __interrupt __raw void vTickISREntry( void )
182 {
183 extern void vPortTickISR( void );
184
185 __bic_SR_register_on_exit( SCG1 + SCG0 + OSCOFF + CPUOFF );
186 vPortTickISR();
187 }
188