begriffs open source - freertos/blob - portable/Rowley/MSP430F449/port.c

1 /*

2 * FreeRTOS SMP Kernel V202110.00

4 *

5 * Permission is hereby granted, free of charge, to any person obtaining a copy of

6 * this software and associated documentation files (the "Software"), to deal in

7 * the Software without restriction, including without limitation the rights to

8 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of

9 * the Software, and to permit persons to whom the Software is furnished to do so,

10 * subject to the following conditions:

11 *

12 * The above copyright notice and this permission notice shall be included in all

13 * copies or substantial portions of the Software.

14 *

15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS

17 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR

18 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER

19 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN

20 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

21 *

22 * https://www.FreeRTOS.org

23 * https://github.com/FreeRTOS

24 *

25 * 1 tab == 4 spaces!

26 */

27

28 /* Scheduler includes. */

29 #include "FreeRTOS.h"

30 #include "task.h"

31

32 /*-----------------------------------------------------------

33 * Implementation of functions defined in portable.h for the MSP430 port.

34 *----------------------------------------------------------*/

35

36 /* Constants required for hardware setup. The tick ISR runs off the ACLK,

37 not the MCLK. */

38 #define portACLK_FREQUENCY_HZ ( ( TickType_t ) 32768 )

39 #define portINITIAL_CRITICAL_NESTING ( ( uint16_t ) 10 )

40 #define portFLAGS_INT_ENABLED ( ( StackType_t ) 0x08 )

41

42 /* We require the address of the pxCurrentTCB variable, but don't want to know

43 any details of its type. */

44 typedef void TCB_t;

45 extern volatile TCB_t * volatile pxCurrentTCB;

46

47 /* Each task maintains a count of the critical section nesting depth. Each

48 time a critical section is entered the count is incremented. Each time a

49 critical section is exited the count is decremented - with interrupts only

50 being re-enabled if the count is zero.

51

52 usCriticalNesting will get set to zero when the scheduler starts, but must

53 not be initialised to zero as this will cause problems during the startup

54 sequence. */

55 volatile uint16_t usCriticalNesting = portINITIAL_CRITICAL_NESTING;

56 /*-----------------------------------------------------------*/

57

58

59 /*

60 * Sets up the periodic ISR used for the RTOS tick. This uses timer 0, but

61 * could have alternatively used the watchdog timer or timer 1.

62 */

63 void prvSetupTimerInterrupt( void );

64 /*-----------------------------------------------------------*/

65

66 /*

67 * Initialise the stack of a task to look exactly as if a call to

68 * portSAVE_CONTEXT had been called.

69 *

70 * See the header file portable.h.

71 */

72 StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )

73 {

74 /*

75 Place a few bytes of known values on the bottom of the stack.

76 This is just useful for debugging and can be included if required.

77

78 *pxTopOfStack = ( StackType_t ) 0x1111;

79 pxTopOfStack--;

80 *pxTopOfStack = ( StackType_t ) 0x2222;

81 pxTopOfStack--;

82 *pxTopOfStack = ( StackType_t ) 0x3333;

83 pxTopOfStack--;

84 */

85

86 /* The msp430 automatically pushes the PC then SR onto the stack before

87 executing an ISR. We want the stack to look just as if this has happened

88 so place a pointer to the start of the task on the stack first - followed

89 by the flags we want the task to use when it starts up. */

90 *pxTopOfStack = ( StackType_t ) pxCode;

91 pxTopOfStack--;

92 *pxTopOfStack = portFLAGS_INT_ENABLED;

93 pxTopOfStack--;

94

95 /* Next the general purpose registers. */

96 *pxTopOfStack = ( StackType_t ) 0x4444;

97 pxTopOfStack--;

98 *pxTopOfStack = ( StackType_t ) 0x5555;

99 pxTopOfStack--;

100 *pxTopOfStack = ( StackType_t ) 0x6666;

101 pxTopOfStack--;

102 *pxTopOfStack = ( StackType_t ) 0x7777;

103 pxTopOfStack--;

104 *pxTopOfStack = ( StackType_t ) 0x8888;

105 pxTopOfStack--;

106 *pxTopOfStack = ( StackType_t ) 0x9999;

107 pxTopOfStack--;

108 *pxTopOfStack = ( StackType_t ) 0xaaaa;

109 pxTopOfStack--;

110 *pxTopOfStack = ( StackType_t ) 0xbbbb;

111 pxTopOfStack--;

112 *pxTopOfStack = ( StackType_t ) 0xcccc;

113 pxTopOfStack--;

114 *pxTopOfStack = ( StackType_t ) 0xdddd;

115 pxTopOfStack--;

116 *pxTopOfStack = ( StackType_t ) 0xeeee;

117 pxTopOfStack--;

118

119 /* When the task starts is will expect to find the function parameter in

120 R15. */

121 *pxTopOfStack = ( StackType_t ) pvParameters;

122 pxTopOfStack--;

123

124 /* A variable is used to keep track of the critical section nesting.

125 This variable has to be stored as part of the task context and is

126 initially set to zero. */

127 *pxTopOfStack = ( StackType_t ) portNO_CRITICAL_SECTION_NESTING;

128

129 /* Return a pointer to the top of the stack we have generated so this can

130 be stored in the task control block for the task. */

131 return pxTopOfStack;

132 }

133 /*-----------------------------------------------------------*/

134

135 void vPortEndScheduler( void )

136 {

137 /* It is unlikely that the MSP430 port will get stopped. If required simply

138 disable the tick interrupt here. */

139 }

140 /*-----------------------------------------------------------*/

141

142 /*

143 * Hardware initialisation to generate the RTOS tick. This uses timer 0

144 * but could alternatively use the watchdog timer or timer 1.

145 */

146 void prvSetupTimerInterrupt( void )

147 {

148 /* Ensure the timer is stopped. */

149 TACTL = 0;

150

151 /* Run the timer of the ACLK. */

152 TACTL = TASSEL_1;

153

154 /* Clear everything to start with. */

155 TACTL |= TACLR;

156

157 /* Set the compare match value according to the tick rate we want. */

158 TACCR0 = portACLK_FREQUENCY_HZ / configTICK_RATE_HZ;

159

160 /* Enable the interrupts. */

161 TACCTL0 = CCIE;

162

163 /* Start up clean. */

164 TACTL |= TACLR;

165

166 /* Up mode. */

167 TACTL |= MC_1;

168 }

169 /*-----------------------------------------------------------*/

170

171

172