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riscv32: rename to riscv

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With the upcoming riscv64 support, it is best to use "riscv" as the
subdirectory name and common symbols as riscv32 and riscv64 support
code is almost identical. Then later decide whether 32-bit or 64-bit
compilation is wanted.

Redirects for the web documentation are also included.

Then zephyrbot complained about this:

"
New files added that are not covered in CODEOWNERS:

dts/riscv/microsemi-miv.dtsi
dts/riscv/riscv32-fe310.dtsi

Please add one or more entries in the CODEOWNERS file to cover
those files
"

So I assigned them to those who created them. Feel free to readjust
as necessary.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
This commit is contained in:
Nicolas Pitre 2019-07-17 13:17:05 -04:00 • committed by Andrew Boie
commit 1f4b5ddd0f
159 changed files with 125 additions and 118 deletions
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67
arch/riscv/core/thread.c Normal file
View file

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/*
* 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 = (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 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 = (u32_t)z_thread_entry_wrapper;
thread->callee_saved.sp = (u32_t)stack_init;
}