| /* |
| * 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); |
| } |