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/*
ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
2011,2012 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_v7m.c
* @brief ARMv7-M architecture port code.
*
* @addtogroup ARMCMx_V7M_CORE
* @{
*/
#include "ch.h"
/*===========================================================================*/
/* Port interrupt handlers. */
/*===========================================================================*/
/**
* @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();
}
#if !CORTEX_SIMPLIFIED_PRIORITY || defined(__DOXYGEN__)
/**
* @brief SVC vector.
* @details The SVC vector is used for exception mode re-entering after a
* context switch.
* @note The PendSV vector is only used in advanced kernel mode.
*/
void SVCallVector(void) {
struct extctx *ctxp;
/* Current PSP value.*/
asm volatile ("mrs %0, PSP" : "=r" (ctxp) : : "memory");
/* Discarding the current exception context and positioning the stack to
point to the real one.*/
ctxp++;
#if CORTEX_USE_FPU
/* Restoring the special register SCB_FPCCR.*/
SCB_FPCCR = (uint32_t)ctxp->fpccr;
SCB_FPCAR = SCB_FPCAR + sizeof (struct extctx);
#endif
asm volatile ("msr PSP, %0" : : "r" (ctxp) : "memory");
port_unlock_from_isr();
}
#endif /* !CORTEX_SIMPLIFIED_PRIORITY */
#if CORTEX_SIMPLIFIED_PRIORITY || defined(__DOXYGEN__)
/**
* @brief PendSV vector.
* @details The PendSV vector is used for exception mode re-entering after a
* context switch.
* @note The PendSV vector is only used in compact kernel mode.
*/
void PendSVVector(void) {
struct extctx *ctxp;
/* Current PSP value.*/
asm volatile ("mrs %0, PSP" : "=r" (ctxp) : : "memory");
/* Discarding the current exception context and positioning the stack to
point to the real one.*/
ctxp++;
#if CORTEX_USE_FPU
/* Restoring the special register SCB_FPCCR.*/
SCB_FPCCR = (uint32_t)ctxp->fpccr;
SCB_FPCAR = SCB_FPCAR + sizeof (struct extctx);
#endif
asm volatile ("msr PSP, %0" : : "r" (ctxp) : "memory");
}
#endif /* CORTEX_SIMPLIFIED_PRIORITY */
/*===========================================================================*/
/* Port exported functions. */
/*===========================================================================*/
/**
* @brief Port-related initialization code.
*/
void _port_init(void) {
/* Initialization of the vector table and priority related settings.*/
SCB_VTOR = CORTEX_VTOR_INIT;
SCB_AIRCR = AIRCR_VECTKEY | AIRCR_PRIGROUP(CORTEX_PRIGROUP_INIT);
/* Initialization of the system vectors used by the port.*/
nvicSetSystemHandlerPriority(HANDLER_SVCALL,
CORTEX_PRIORITY_MASK(CORTEX_PRIORITY_SVCALL));
nvicSetSystemHandlerPriority(HANDLER_PENDSV,
CORTEX_PRIORITY_MASK(CORTEX_PRIORITY_PENDSV));
nvicSetSystemHandlerPriority(HANDLER_SYSTICK,
CORTEX_PRIORITY_MASK(CORTEX_PRIORITY_SYSTICK));
}
#if !CH_OPTIMIZE_SPEED
void _port_lock(void) {
register uint32_t tmp asm ("r3") = CORTEX_BASEPRI_KERNEL;
asm volatile ("msr BASEPRI, %0" : : "r" (tmp) : "memory");
}
void _port_unlock(void) {
register uint32_t tmp asm ("r3") = CORTEX_BASEPRI_DISABLED;
asm volatile ("msr BASEPRI, %0" : : "r" (tmp) : "memory");
}
#endif
/**
* @brief Exception exit redirection to _port_switch_from_isr().
*/
void _port_irq_epilogue(void) {
port_lock_from_isr();
if ((SCB_ICSR & ICSR_RETTOBASE) != 0) {
struct extctx *ctxp;
/* Current PSP value.*/
asm volatile ("mrs %0, PSP" : "=r" (ctxp) : : "memory");
/* Adding an artificial exception return context, there is no need to
populate it fully.*/
ctxp--;
asm volatile ("msr PSP, %0" : : "r" (ctxp) : "memory");
ctxp->xpsr = (regarm_t)0x01000000;
/* The exit sequence is different depending on if a preemption is
required or not.*/
if (chSchIsPreemptionRequired()) {
/* Preemption is required we need to enforce a context switch.*/
ctxp->pc = (void *)_port_switch_from_isr;
#if CORTEX_USE_FPU
/* Triggering a lazy FPU state save.*/
asm volatile ("vmrs APSR_nzcv, FPSCR" : : : "memory");
#endif
}
else {
/* Preemption not required, we just need to exit the exception
atomically.*/
ctxp->pc = (void *)_port_exit_from_isr;
}
#if CORTEX_USE_FPU
{
uint32_t fpccr;
/* Saving the special register SCB_FPCCR into the reserved offset of
the Cortex-M4 exception frame.*/
(ctxp + 1)->fpccr = (regarm_t)(fpccr = SCB_FPCCR);
/* Now the FPCCR is modified in order to not restore the FPU status
from the artificial return context.*/
SCB_FPCCR = fpccr | FPCCR_LSPACT;
}
#endif
/* 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 Post-IRQ switch code.
* @details Exception handlers return here for context switching.
*/
#if !defined(__DOXYGEN__)
__attribute__((naked))
#endif
void _port_switch_from_isr(void) {
dbg_check_lock();
chSchDoReschedule();
dbg_check_unlock();
asm volatile ("_port_exit_from_isr:" : : : "memory");
#if !CORTEX_SIMPLIFIED_PRIORITY || defined(__DOXYGEN__)
asm volatile ("svc #0");
#else /* CORTEX_SIMPLIFIED_PRIORITY */
SCB_ICSR = ICSR_PENDSVSET;
port_unlock();
while (TRUE)
;
#endif /* CORTEX_SIMPLIFIED_PRIORITY */
}
/**
* @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) {
asm volatile ("push {r4, r5, r6, r7, r8, r9, r10, r11, lr}"
: : : "memory");
#if CORTEX_USE_FPU
asm volatile ("vpush {s16-s31}" : : : "memory");
#endif
asm volatile ("str sp, [%1, #12] \n\t"
"ldr sp, [%0, #12]" : : "r" (ntp), "r" (otp));
#if CORTEX_USE_FPU
asm volatile ("vpop {s16-s31}" : : : "memory");
#endif
asm volatile ("pop {r4, r5, r6, r7, r8, r9, r10, r11, pc}"
: : : "memory");
}
/**
* @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) {
chSysUnlock();
asm volatile ("mov r0, r5 \n\t"
"blx r4 \n\t"
"bl chThdExit");
}
/** @} */
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