blob: 4bb281e764a8114df6949962b1bd9272b9f9e173 [file] [log] [blame]
/*
* 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 _thread_entry_wrapper(k_thread_entry_t thread,
void *arg1,
void *arg2,
void *arg3);
void _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 = K_THREAD_STACK_BUFFER(stack);
_ASSERT_VALID_PRIO(priority, thread_func);
struct __esf *stack_init;
_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 = (u32_t)thread_func;
stack_init->a1 = (u32_t)arg1;
stack_init->a2 = (u32_t)arg2;
stack_init->a3 = (u32_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 RISCV32 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 _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 _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 = (u32_t)_thread_entry_wrapper;
thread->callee_saved.sp = (u32_t)stack_init;
thread_monitor_init(thread);
}