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 /*-----------------------------------------------------------
30 * Implementation of functions defined in portable.h for the RISC-V port.
31 *----------------------------------------------------------*/
32
33 /* Scheduler includes. */
34 #include "FreeRTOS.h"
35 #include "task.h"
36 #include "portmacro.h"
37
38 /* Standard includes. */
39 #include "string.h"
40
41 #ifdef configCLINT_BASE_ADDRESS
42 #warning "The configCLINT_BASE_ADDRESS constant has been deprecated. configMTIME_BASE_ADDRESS and configMTIMECMP_BASE_ADDRESS are currently being derived from the (possibly 0) configCLINT_BASE_ADDRESS setting. Please update to define configMTIME_BASE_ADDRESS and configMTIMECMP_BASE_ADDRESS directly in place of configCLINT_BASE_ADDRESS. See www.FreeRTOS.org/Using-FreeRTOS-on-RISC-V.html"
43 #endif
44
45 #ifndef configMTIME_BASE_ADDRESS
46 #warning "configMTIME_BASE_ADDRESS must be defined in FreeRTOSConfig.h. If the target chip includes a memory-mapped mtime register then set configMTIME_BASE_ADDRESS to the mapped address. Otherwise set configMTIME_BASE_ADDRESS to 0. See www.FreeRTOS.org/Using-FreeRTOS-on-RISC-V.html"
47 #endif
48
49 #ifndef configMTIMECMP_BASE_ADDRESS
50 #warning "configMTIMECMP_BASE_ADDRESS must be defined in FreeRTOSConfig.h. If the target chip includes a memory-mapped mtimecmp register then set configMTIMECMP_BASE_ADDRESS to the mapped address. Otherwise set configMTIMECMP_BASE_ADDRESS to 0. See www.FreeRTOS.org/Using-FreeRTOS-on-RISC-V.html"
51 #endif
52
53 /* Let the user override the pre-loading of the initial RA. */
54 #ifdef configTASK_RETURN_ADDRESS
55 #define portTASK_RETURN_ADDRESS configTASK_RETURN_ADDRESS
56 #else
57 #define portTASK_RETURN_ADDRESS 0
58 #endif
59
60 /* The stack used by interrupt service routines. Set configISR_STACK_SIZE_WORDS
61 * to use a statically allocated array as the interrupt stack. Alternative leave
62 * configISR_STACK_SIZE_WORDS undefined and update the linker script so that a
63 * linker variable names __freertos_irq_stack_top has the same value as the top
64 * of the stack used by main. Using the linker script method will repurpose the
65 * stack that was used by main before the scheduler was started for use as the
66 * interrupt stack after the scheduler has started. */
67 #ifdef configISR_STACK_SIZE_WORDS
68 static __attribute__( ( aligned( 16 ) ) ) StackType_t xISRStack[ configISR_STACK_SIZE_WORDS ] = { 0 };
69 const StackType_t xISRStackTop = ( StackType_t ) &( xISRStack[ configISR_STACK_SIZE_WORDS & ~portBYTE_ALIGNMENT_MASK ] );
70
71 /* Don't use 0xa5 as the stack fill bytes as that is used by the kernel for
72 * the task stacks, and so will legitimately appear in many positions within
73 * the ISR stack. */
74 #define portISR_STACK_FILL_BYTE 0xee
75 #else
76 extern const uint32_t __freertos_irq_stack_top[];
77 const StackType_t xISRStackTop = ( StackType_t ) __freertos_irq_stack_top;
78 #endif
79
80 /*
81 * Setup the timer to generate the tick interrupts. The implementation in this
82 * file is weak to allow application writers to change the timer used to
83 * generate the tick interrupt.
84 */
85 void vPortSetupTimerInterrupt( void ) __attribute__( ( weak ) );
86
87 /*-----------------------------------------------------------*/
88
89 /* Used to program the machine timer compare register. */
90 uint64_t ullNextTime = 0ULL;
91 const uint64_t * pullNextTime = &ullNextTime;
92 const size_t uxTimerIncrementsForOneTick = ( size_t ) ( ( configCPU_CLOCK_HZ ) / ( configTICK_RATE_HZ ) ); /* Assumes increment won't go over 32-bits. */
93 uint32_t const ullMachineTimerCompareRegisterBase = configMTIMECMP_BASE_ADDRESS;
94 volatile uint64_t * pullMachineTimerCompareRegister = NULL;
95
96 /* Holds the critical nesting value - deliberately non-zero at start up to
97 * ensure interrupts are not accidentally enabled before the scheduler starts. */
98 size_t xCriticalNesting = ( size_t ) 0xaaaaaaaa;
99 size_t * pxCriticalNesting = &xCriticalNesting;
100
101 /* Used to catch tasks that attempt to return from their implementing function. */
102 size_t xTaskReturnAddress = ( size_t ) portTASK_RETURN_ADDRESS;
103
104 /* Set configCHECK_FOR_STACK_OVERFLOW to 3 to add ISR stack checking to task
105 * stack checking. A problem in the ISR stack will trigger an assert, not call
106 * the stack overflow hook function (because the stack overflow hook is specific
107 * to a task stack, not the ISR stack). */
108 #if defined( configISR_STACK_SIZE_WORDS ) && ( configCHECK_FOR_STACK_OVERFLOW > 2 )
109 #warning "This path not tested, or even compiled yet."
110
111 static const uint8_t ucExpectedStackBytes[] =
112 {
113 portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, \
114 portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, \
115 portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, \
116 portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, \
117 portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE, portISR_STACK_FILL_BYTE
118 }; \
119
120 #define portCHECK_ISR_STACK() configASSERT( ( memcmp( ( void * ) xISRStack, ( void * ) ucExpectedStackBytes, sizeof( ucExpectedStackBytes ) ) == 0 ) )
121 #else /* if defined( configISR_STACK_SIZE_WORDS ) && ( configCHECK_FOR_STACK_OVERFLOW > 2 ) */
122 /* Define the function away. */
123 #define portCHECK_ISR_STACK()
124 #endif /* configCHECK_FOR_STACK_OVERFLOW > 2 */
125
126 /*-----------------------------------------------------------*/
127
128 #if ( configMTIME_BASE_ADDRESS != 0 ) && ( configMTIMECMP_BASE_ADDRESS != 0 )
129
vPortSetupTimerInterrupt(void)130 void vPortSetupTimerInterrupt( void )
131 {
132 uint32_t ulCurrentTimeHigh, ulCurrentTimeLow;
133 volatile uint32_t * const pulTimeHigh = ( volatile uint32_t * const ) ( ( configMTIME_BASE_ADDRESS ) + 4UL ); /* 8-byte type so high 32-bit word is 4 bytes up. */
134 volatile uint32_t * const pulTimeLow = ( volatile uint32_t * const ) ( configMTIME_BASE_ADDRESS );
135 volatile uint32_t ulHartId;
136
137 __asm volatile ( "csrr %0, mhartid" : "=r" ( ulHartId ) );
138
139 pullMachineTimerCompareRegister = ( volatile uint64_t * ) ( ullMachineTimerCompareRegisterBase + ( ulHartId * sizeof( uint64_t ) ) );
140
141 do
142 {
143 ulCurrentTimeHigh = *pulTimeHigh;
144 ulCurrentTimeLow = *pulTimeLow;
145 } while( ulCurrentTimeHigh != *pulTimeHigh );
146
147 ullNextTime = ( uint64_t ) ulCurrentTimeHigh;
148 ullNextTime <<= 32ULL; /* High 4-byte word is 32-bits up. */
149 ullNextTime |= ( uint64_t ) ulCurrentTimeLow;
150 ullNextTime += ( uint64_t ) uxTimerIncrementsForOneTick;
151 *pullMachineTimerCompareRegister = ullNextTime;
152
153 /* Prepare the time to use after the next tick interrupt. */
154 ullNextTime += ( uint64_t ) uxTimerIncrementsForOneTick;
155 }
156
157 #endif /* ( configMTIME_BASE_ADDRESS != 0 ) && ( configMTIME_BASE_ADDRESS != 0 ) */
158 /*-----------------------------------------------------------*/
159
xPortStartScheduler(void)160 BaseType_t xPortStartScheduler( void )
161 {
162 extern void xPortStartFirstTask( void );
163
164 #if ( configASSERT_DEFINED == 1 )
165 {
166 /* Check alignment of the interrupt stack - which is the same as the
167 * stack that was being used by main() prior to the scheduler being
168 * started. */
169 configASSERT( ( xISRStackTop & portBYTE_ALIGNMENT_MASK ) == 0 );
170
171 #ifdef configISR_STACK_SIZE_WORDS
172 {
173 memset( ( void * ) xISRStack, portISR_STACK_FILL_BYTE, sizeof( xISRStack ) );
174 }
175 #endif /* configISR_STACK_SIZE_WORDS */
176 }
177 #endif /* configASSERT_DEFINED */
178
179 /* If there is a CLINT then it is ok to use the default implementation
180 * in this file, otherwise vPortSetupTimerInterrupt() must be implemented to
181 * configure whichever clock is to be used to generate the tick interrupt. */
182 vPortSetupTimerInterrupt();
183
184 #if ( ( configMTIME_BASE_ADDRESS != 0 ) && ( configMTIMECMP_BASE_ADDRESS != 0 ) )
185 {
186 /* Enable mtime and external interrupts. 1<<7 for timer interrupt,
187 * 1<<11 for external interrupt. _RB_ What happens here when mtime is
188 * not present as with pulpino? */
189 __asm volatile ( "csrs mie, %0" ::"r" ( 0x880 ) );
190 }
191 #endif /* ( configMTIME_BASE_ADDRESS != 0 ) && ( configMTIMECMP_BASE_ADDRESS != 0 ) */
192
193 xPortStartFirstTask();
194
195 /* Should not get here as after calling xPortStartFirstTask() only tasks
196 * should be executing. */
197 return pdFAIL;
198 }
199 /*-----------------------------------------------------------*/
200
vPortEndScheduler(void)201 void vPortEndScheduler( void )
202 {
203 /* Not implemented. */
204 for( ; ; )
205 {
206 }
207 }
208 /*-----------------------------------------------------------*/
209
