68 lines
2.4 KiB
C
68 lines
2.4 KiB
C
/*
|
|
* Copyright (c) 2016 Jean-Paul Etienne <fractalclone@gmail.com>
|
|
*
|
|
* SPDX-License-Identifier: Apache-2.0
|
|
*/
|
|
|
|
#include <kernel.h>
|
|
#include <arch/cpu.h>
|
|
#include <kernel_structs.h>
|
|
#include <wait_q.h>
|
|
#include <string.h>
|
|
|
|
void z_thread_entry_wrapper(k_thread_entry_t thread,
|
|
void *arg1,
|
|
void *arg2,
|
|
void *arg3);
|
|
|
|
void z_new_thread(struct k_thread *thread, k_thread_stack_t *stack,
|
|
size_t stack_size, k_thread_entry_t thread_func,
|
|
void *arg1, void *arg2, void *arg3,
|
|
int priority, unsigned int options)
|
|
{
|
|
char *stack_memory = Z_THREAD_STACK_BUFFER(stack);
|
|
Z_ASSERT_VALID_PRIO(priority, thread_func);
|
|
|
|
struct __esf *stack_init;
|
|
|
|
z_new_thread_init(thread, stack_memory, stack_size, priority, options);
|
|
|
|
/* Initial stack frame for thread */
|
|
stack_init = (struct __esf *)
|
|
STACK_ROUND_DOWN(stack_memory +
|
|
stack_size - sizeof(struct __esf));
|
|
|
|
/* Setup the initial stack frame */
|
|
stack_init->a0 = (ulong_t)thread_func;
|
|
stack_init->a1 = (ulong_t)arg1;
|
|
stack_init->a2 = (ulong_t)arg2;
|
|
stack_init->a3 = (ulong_t)arg3;
|
|
/*
|
|
* Following the RISC-V architecture,
|
|
* the MSTATUS register (used to globally enable/disable interrupt),
|
|
* as well as the MEPC register (used to by the core to save the
|
|
* value of the program counter at which an interrupt/exception occcurs)
|
|
* need to be saved on the stack, upon an interrupt/exception
|
|
* and restored prior to returning from the interrupt/exception.
|
|
* This shall allow to handle nested interrupts.
|
|
*
|
|
* Given that context switching is performed via a system call exception
|
|
* within the RISCV architecture implementation, initially set:
|
|
* 1) MSTATUS to SOC_MSTATUS_DEF_RESTORE in the thread stack to enable
|
|
* interrupts when the newly created thread will be scheduled;
|
|
* 2) MEPC to the address of the z_thread_entry_wrapper in the thread
|
|
* stack.
|
|
* Hence, when going out of an interrupt/exception/context-switch,
|
|
* after scheduling the newly created thread:
|
|
* 1) interrupts will be enabled, as the MSTATUS register will be
|
|
* restored following the MSTATUS value set within the thread stack;
|
|
* 2) the core will jump to z_thread_entry_wrapper, as the program
|
|
* counter will be restored following the MEPC value set within the
|
|
* thread stack.
|
|
*/
|
|
stack_init->mstatus = SOC_MSTATUS_DEF_RESTORE;
|
|
stack_init->mepc = (ulong_t)z_thread_entry_wrapper;
|
|
|
|
thread->callee_saved.sp = (ulong_t)stack_init;
|
|
}
|