armcm_boot: Add generic code for early board init on armcm machines

Add basic ARM Cortex-M C init code and build linker scripts to
src/generic/ code.  This can be used to simplify the various ARM board
code.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2019-08-21 12:05:56 -04:00
parent 351910c5ac
commit 2a2cf1f536
5 changed files with 202 additions and 0 deletions

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@ -209,6 +209,50 @@ const int initial_pins_size PROGMEM = ARRAY_SIZE(initial_pins);
Handlers.append(HandleInitialPins())
######################################################################
# ARM IRQ vector table generation
######################################################################
# Create ARM IRQ vector table from interrupt handler declarations
class Handle_arm_irq:
def __init__(self):
self.irqs = {}
self.ctr_dispatch = { 'DECL_ARMCM_IRQ': self.decl_armcm_irq }
def decl_armcm_irq(self, req):
func, num = req.split()[1:]
num = decode_integer(num)
if num in self.irqs and self.irqs[num] != func:
error("Conflicting IRQ definition %d (old %s new %s)"
% (num, self.irqs[num], func))
self.irqs[num] = func
def update_data_dictionary(self, data):
pass
def generate_code(self, options):
armcm_offset = 16
if 1 - armcm_offset not in self.irqs:
# The ResetHandler was not defined - don't build VectorTable
return ""
max_irq = max(self.irqs.keys())
table = [" DefaultHandler,\n"] * (max_irq + armcm_offset + 1)
defs = []
for num, func in self.irqs.items():
if num < 1 - armcm_offset:
error("Invalid IRQ %d (%s)" % (num, func))
defs.append("extern void %s(void);\n" % (func,))
table[num + armcm_offset] = " %s,\n" % (func,)
table[0] = " &_stack_end,\n"
fmt = """
extern void DefaultHandler(void);
extern uint32_t _stack_end;
%s
const void *VectorTable[] __visible __section(".vector_table") = {
%s};
"""
return fmt % (''.join(defs), ''.join(table))
Handlers.append(Handle_arm_irq())
######################################################################
# Wire protocol commands and responses
######################################################################

73
src/generic/armcm_boot.c Normal file
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@ -0,0 +1,73 @@
// ARM Cortex-M vector table and initial bootup handling
//
// Copyright (C) 2019 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include "armcm_boot.h" // DECL_ARMCM_IRQ
#include "board/internal.h" // SystemInit
// Symbols created by armcm_boot.lds.S linker script
extern uint32_t _data_start, _data_end, _data_flash;
extern uint32_t _bss_start, _bss_end, _stack_start;
/****************************************************************
* Basic interrupt handlers
****************************************************************/
// Initial code entry point - invoked by the processor after a reset
void
ResetHandler(void)
{
// Copy global variables from flash to ram
uint32_t count = (&_data_end - &_data_start) * 4;
__builtin_memcpy(&_data_start, &_data_flash, count);
// Clear the bss segment
__builtin_memset(&_bss_start, 0, (&_bss_end - &_bss_start) * 4);
barrier();
// Initializing the C library isn't needed...
//__libc_init_array();
// Initialize the machine
SystemInit();
// Run the main code
extern int main(void);
main();
// The main() call should not return
for (;;)
;
}
DECL_ARMCM_IRQ(ResetHandler, -15);
// Code called for any undefined interrupts
void
DefaultHandler(void)
{
for (;;)
;
}
/****************************************************************
* Dynamic memory range
****************************************************************/
// Return the start of memory available for dynamic allocations
void *
dynmem_start(void)
{
return &_bss_end;
}
// Return the end of memory available for dynamic allocations
void *
dynmem_end(void)
{
return &_stack_start;
}

20
src/generic/armcm_boot.h Normal file
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@ -0,0 +1,20 @@
#ifndef __GENERIC_ARMCM_BOOT_H
#define __GENERIC_ARMCM_BOOT_H
#include "ctr.h" // DECL_CTR_INT
// Declare an IRQ handler
#define DECL_ARMCM_IRQ(FUNC, NUM) \
DECL_CTR_INT("DECL_ARMCM_IRQ " __stringify(FUNC), (NUM))
// Statically declare an IRQ handler and run-time enable it
#define armcm_enable_irq(FUNC, NUM, PRIORITY) do { \
DECL_ARMCM_IRQ(FUNC, (NUM)); \
NVIC_SetPriority((NUM), (PRIORITY)); \
NVIC_EnableIRQ((NUM)); \
} while (0)
// Vectors created by scripts/buildcommands.py from DECL_ARMCM_IRQ commands
extern const void * const VectorTable[];
#endif // armcm_boot.h

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@ -0,0 +1,63 @@
// Generic ARM Cortex-M linker script
//
// Copyright (C) 2019 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU GPLv3 license.
#include "autoconf.h" // CONFIG_FLASH_START
OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
OUTPUT_ARCH(arm)
MEMORY
{
rom (rx) : ORIGIN = CONFIG_FLASH_START , LENGTH = CONFIG_FLASH_SIZE
ram (rwx) : ORIGIN = CONFIG_RAM_START , LENGTH = CONFIG_RAM_SIZE
}
SECTIONS
{
.text : {
. = ALIGN(4);
KEEP(*(.vector_table))
*(.text .text.*)
*(.rodata .rodata*)
} > rom
. = ALIGN(4);
_data_flash = .;
.data : AT (_data_flash)
{
. = ALIGN(4);
_data_start = .;
*(.ramfunc .ramfunc.*);
*(.data .data.*);
. = ALIGN(4);
_data_end = .;
} > ram
.bss (NOLOAD) :
{
. = ALIGN(4);
_bss_start = .;
*(.bss .bss.*)
*(COMMON)
. = ALIGN(4);
_bss_end = .;
} > ram
_stack_start = CONFIG_RAM_START + CONFIG_RAM_SIZE - CONFIG_STACK_SIZE ;
.stack _stack_start (NOLOAD) :
{
. = . + CONFIG_STACK_SIZE;
_stack_end = .;
} > ram
/DISCARD/ : {
// The .init/.fini sections are used by __libc_init_array(), but
// that isn't needed so no need to include them in the binary.
*(.init)
*(.fini)
}
}

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@ -5,6 +5,7 @@
// This file may be distributed under the terms of the GNU GPLv3 license.
#include "autoconf.h" // CONFIG_CLOCK_FREQ
#include "armcm_boot.h" // DECL_ARMCM_IRQ
#include "board/internal.h" // SysTick
#include "board/irq.h" // irq_disable
#include "board/misc.h" // timer_from_us
@ -160,6 +161,7 @@ SysTick_Handler(void)
timer_set_diff(diff);
irq_enable();
}
DECL_ARMCM_IRQ(SysTick_Handler, SysTick_IRQn);
// Make sure timer_repeat_until doesn't wrap 32bit comparisons
void