1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
|
/*
ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
2011 Giovanni Di Sirio.
This file is part of ChibiOS/RT.
ChibiOS/RT is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
ChibiOS/RT is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @file GCC/ARMCMx/chcore_v6m.c
* @brief ARMv6-M architecture port code.
*
* @addtogroup ARMCMx_V6M_CORE
* @{
*/
#include "ch.h"
/**
* @brief System Timer vector.
* @details This interrupt is used as system tick.
* @note The timer must be initialized in the startup code.
*/
CH_IRQ_HANDLER(SysTickVector) {
CH_IRQ_PROLOGUE();
chSysLockFromIsr();
chSysTimerHandlerI();
chSysUnlockFromIsr();
CH_IRQ_EPILOGUE();
}
/**
* @brief NMI vector.
* @details The NMI vector is used for exception mode re-entering after a
* context switch.
*/
void NMIVector(void) {
register struct extctx *ctxp;
/* Discarding the current exception context and positioning the stack to
point to the real one.*/
asm volatile ("mrs %0, PSP" : "=r" (ctxp) : : "memory");
ctxp++;
asm volatile ("msr PSP, %0" : : "r" (ctxp) : "memory");
port_unlock_from_isr();
}
/**
* @brief Post-IRQ switch code.
* @details The switch is performed in thread context then an NMI exception
* is enforced in order to return to the exact point before the
* preemption.
*/
#if !defined(__DOXYGEN__)
__attribute__((naked))
#endif
void _port_switch_from_isr(void) {
chSchDoRescheduleI();
SCB_ICSR = ICSR_NMIPENDSET;
/* The following loop should never be executed, the NMI will kick in
immediately.*/
while (TRUE)
;
}
#define PUSH_CONTEXT(sp) { \
asm volatile ("push {r4, r5, r6, r7, lr} \n\t" \
"mov r4, r8 \n\t" \
"mov r5, r9 \n\t" \
"mov r6, r10 \n\t" \
"mov r7, r11 \n\t" \
"push {r4, r5, r6, r7}" : : : "memory"); \
}
#define POP_CONTEXT(sp) { \
asm volatile ("pop {r4, r5, r6, r7} \n\t" \
"mov r8, r4 \n\t" \
"mov r9, r5 \n\t" \
"mov r10, r6 \n\t" \
"mov r11, r7 \n\t" \
"pop {r4, r5, r6, r7, pc}" : : "r" (sp) : "memory"); \
}
/**
* @brief Performs a context switch between two threads.
* @details This is the most critical code in any port, this function
* is responsible for the context switch between 2 threads.
* @note The implementation of this code affects <b>directly</b> the context
* switch performance so optimize here as much as you can.
*
* @param[in] ntp the thread to be switched in
* @param[in] otp the thread to be switched out
*/
#if !defined(__DOXYGEN__)
__attribute__((naked))
#endif
void port_switch(Thread *ntp, Thread *otp) {
register struct intctx *r13 asm ("r13");
/* Stack overflow check, if enabled.*/
#if CH_DBG_ENABLE_STACK_CHECK
if ((void *)(r13 - 1) < (void *)(otp + 1))
asm volatile ("movs r0, #0 \n\t"
"b chDbgPanic");
#endif /* CH_DBG_ENABLE_STACK_CHECK */
PUSH_CONTEXT(r13);
otp->p_ctx.r13 = r13;
r13 = ntp->p_ctx.r13;
POP_CONTEXT(r13);
}
/**
* @brief IRQ epilogue code.
*
* @param[in] lr value of the @p LR register on ISR entry
*/
void _port_irq_epilogue(regarm_t lr) {
if (lr != (regarm_t)0xFFFFFFF1) {
port_lock_from_isr();
if (chSchIsRescRequiredExI()) {
register struct extctx *ctxp;
/* Adding an artificial exception return context, there is no need to
populate it fully.*/
asm volatile ("mrs %0, PSP" : "=r" (ctxp) : : "memory");
ctxp--;
asm volatile ("msr PSP, %0" : : "r" (ctxp) : "memory");
ctxp->pc = _port_switch_from_isr;
ctxp->xpsr = (regarm_t)0x01000000;
/* Note, returning without unlocking is intentional, this is done in
order to keep the rest of the context switching atomic.*/
return;
}
port_unlock_from_isr();
}
}
/**
* @brief Start a thread by invoking its work function.
* @details If the work function returns @p chThdExit() is automatically
* invoked.
*/
void _port_thread_start(void) {
port_unlock();
asm volatile ("mov r0, r5 \n\t"
"blx r4 \n\t"
"bl chThdExit");
}
/** @} */
|