walnux/arch/arm/arm/arm_initialstate.c
Luchian Mihai c2f9368c7e
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2025-10-31 17:58:46 +02:00

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C

/****************************************************************************
* arch/arm/src/arm/arm_initialstate.c
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdint.h>
#include <string.h>
#include <nuttx/arch.h>
#include "arm.h"
#include "arm_internal.h"
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: up_initial_state
*
* Description:
* A new thread is being started and a new TCB
* has been created. This function is called to initialize
* the processor specific portions of the new TCB.
*
* This function must setup the initial architecture registers
* and/or stack so that execution will begin at tcb->start
* on the next context switch.
*
****************************************************************************/
void up_initial_state(struct tcb_s *tcb)
{
struct xcptcontext *xcp = &tcb->xcp;
uint32_t cpsr;
/* Initialize the initial exception register context structure */
memset(xcp, 0, sizeof(struct xcptcontext));
/* Initialize the idle thread stack */
if (tcb->pid == IDLE_PROCESS_ID)
{
tcb->stack_alloc_ptr = (void *)(g_idle_topstack -
CONFIG_IDLETHREAD_STACKSIZE);
tcb->stack_base_ptr = tcb->stack_alloc_ptr;
tcb->adj_stack_size = CONFIG_IDLETHREAD_STACKSIZE;
#ifdef CONFIG_STACK_COLORATION
/* If stack debug is enabled, then fill the stack with a
* recognizable value that we can use later to test for high
* water marks.
*/
arm_stack_color(tcb->stack_alloc_ptr, 0);
#endif /* CONFIG_STACK_COLORATION */
return;
}
/* Initialize the context registers to stack top */
xcp->regs = (void *)((uint32_t)tcb->stack_base_ptr +
tcb->adj_stack_size -
XCPTCONTEXT_SIZE);
/* Initialize the xcp registers */
memset(xcp->regs, 0, XCPTCONTEXT_SIZE);
/* Save the initial stack pointer */
xcp->regs[REG_SP] = (uint32_t)tcb->stack_base_ptr +
tcb->adj_stack_size;
/* Save the task entry point */
xcp->regs[REG_PC] = (uint32_t)tcb->start;
/* If this task is running PIC, then set the PIC base register to the
* address of the allocated D-Space region.
*/
#ifdef CONFIG_PIC
if (tcb->dspace != NULL)
{
/* Set the PIC base register (probably R10) to the address of the
* alloacated D-Space region.
*/
xcp->regs[REG_PIC] = (uint32_t)tcb->dspace->region;
}
#endif
/* Set supervisor- or user-mode, depending on how NuttX is configured and
* what kind of thread is being started. Disable FIQs in any event
*/
#ifdef CONFIG_BUILD_KERNEL
if ((tcb->flags & TCB_FLAG_TTYPE_MASK) == TCB_FLAG_TTYPE_KERNEL)
{
/* It is a kernel thread.. set supervisor mode */
cpsr = PSR_MODE_SYS | PSR_F_BIT;
}
else
{
/* It is a normal task or a pthread. Set user mode */
cpsr = PSR_MODE_USR | PSR_F_BIT;
}
#else
/* If the kernel build is not selected, then all threads run in
* supervisor-mode.
*/
cpsr = PSR_MODE_SYS | PSR_F_BIT;
#endif
/* Enable or disable interrupts, based on user configuration */
#ifdef CONFIG_SUPPRESS_INTERRUPTS
cpsr |= PSR_I_BIT;
#endif
#ifdef CONFIG_ARM_THUMB
cpsr |= PSR_T_BIT;
#endif
xcp->regs[REG_CPSR] = cpsr;
}