Hi Everyone,
I’m trying to handle local timer interrupts but I’ve got some problems.
I wrote an ISR which is quite similar to the example in ‘demo_gpio’. For debugging I toggle the blue LED.
In ‘init.c’ I changed two things:
-
Also activate the green LED at the beginning of ‘handle_trap()’ to check whether I jump into this function or not.
-
‘#define USE_M_TIME’
When I start this program on the HiFive 1 the red LED blinks for two seconds.
After this the program freezes.
So why there is no jump into ‘handle_trap()’ -> ‘handle_m_time_interrupt()’?
What I have to do?
Thank you!
main.c
#include <stdio.h>
#include <stdint.h>
#include "stdatomic.h"
#include <unistd.h>
#include "platform.h"
#include "encoding.h"
#include "plic/plic_driver.h"
// Entry Point for Machine Timer Interrupt Handler
void handle_m_time_interrupt()
{
// Debugging
GPIO_REG(GPIO_OUTPUT_VAL) ^= (1 << BLUE_LED_OFFSET);
clear_csr(mie, MIP_MTIP);
volatile uint64_t * mtime = (uint64_t*) (CLINT_CTRL_ADDR + CLINT_MTIME);
volatile uint64_t * mtimecmp = (uint64_t*) (CLINT_CTRL_ADDR + CLINT_MTIMECMP);
uint64_t now = *mtime;
uint64_t then = now + 2 * RTC_FREQ;
*mtimecmp = then;
set_csr(mie, MIP_MTIP);
}
void waitFor(unsigned long time)
{
for(volatile unsigned long i = 0; i < time; i++);
}
// Red LED
void ledRed(unsigned long time)
{
GPIO_REG(GPIO_OUTPUT_VAL) &= ~(1 << RED_LED_OFFSET);
waitFor(time);
GPIO_REG(GPIO_OUTPUT_VAL) |= (1 << RED_LED_OFFSET);
waitFor(time);
}
// Green LED
void ledGreen(unsigned long time)
{
GPIO_REG(GPIO_OUTPUT_VAL) &= ~(1 << GREEN_LED_OFFSET);
waitFor(time);
GPIO_REG(GPIO_OUTPUT_VAL) |= (1 << GREEN_LED_OFFSET);
waitFor(time);
}
// Blue LED
void ledBlue(unsigned long time)
{
GPIO_REG(GPIO_OUTPUT_VAL) &= ~(1 << BLUE_LED_OFFSET);
waitFor(time);
GPIO_REG(GPIO_OUTPUT_VAL) |= (1 << BLUE_LED_OFFSET);
waitFor(time);
}
int main(int argc, char** argv)
{
clear_csr(mie, MIP_MEIP); // Extern PLIC
clear_csr(mie, MIP_MTIP); // Local Timer
clear_csr(mie, MIP_MSIP); // Software
// Timer Config
volatile uint64_t * mtime = (uint64_t*) (CLINT_CTRL_ADDR + CLINT_MTIME);
volatile uint64_t * mtimecmp = (uint64_t*) (CLINT_CTRL_ADDR + CLINT_MTIMECMP);
uint64_t now = *mtime;
uint64_t then = now + 2*RTC_FREQ;
*mtimecmp = then;
set_csr(mie, MIP_MTIP); // Timer
set_csr(mstatus, MSTATUS_MIE); // General
GPIO_REG(GPIO_OUTPUT_EN) |= (1 << GREEN_LED_OFFSET);
GPIO_REG(GPIO_OUTPUT_EN) |= (1 << RED_LED_OFFSET);
GPIO_REG(GPIO_OUTPUT_EN) |= (1 << BLUE_LED_OFFSET);
// LEDs off
GPIO_REG(GPIO_OUTPUT_VAL) |= (1 << BLUE_LED_OFFSET);
GPIO_REG(GPIO_OUTPUT_VAL) |= (1 << RED_LED_OFFSET);
GPIO_REG(GPIO_OUTPUT_VAL) |= (1 << GREEN_LED_OFFSET);
while(1)
{
ledRed(300000); // Debugging
}
return 0;
}
init.c
#include <stdint.h>
#include <stdio.h>
#include <unistd.h>
#include "platform.h"
#include "encoding.h"
#define USE_M_TIME
extern int main(int argc, char** argv);
extern void trap_entry();
..........
#ifdef USE_PLIC
extern void handle_m_ext_interrupt();
#endif
#ifdef USE_M_TIME
extern void handle_m_time_interrupt();
#endif
uintptr_t handle_trap(uintptr_t mcause, uintptr_t epc)
{
// Green LED
GPIO_REG(GPIO_OUTPUT_VAL) &= ~(1 << GREEN_LED_OFFSET);
if (0){
#ifdef USE_PLIC
// External Machine-Level interrupt from PLIC
} else if ((mcause & MCAUSE_INT) && ((mcause & MCAUSE_CAUSE) == IRQ_M_EXT)) {
handle_m_ext_interrupt();
#endif
#ifdef USE_M_TIME
// External Machine-Level interrupt from PLIC
} else if ((mcause & MCAUSE_INT) && ((mcause & MCAUSE_CAUSE) == IRQ_M_TIMER)){
handle_m_time_interrupt();
#endif
}
else {
write(1, "trap\n", 5);
_exit(1 + mcause);
}
return epc;
}
void _init()
{
#ifndef NO_INIT
use_default_clocks();
use_pll(0, 0, 1, 31, 1);
uart_init(115200);
printf("core freq at %d Hz\n", get_cpu_freq());
write_csr(mtvec, &trap_entry);
if (read_csr(misa) & (1 << ('F' - 'A'))) { // if F extension is present
write_csr(mstatus, MSTATUS_FS); // allow FPU instructions without trapping
write_csr(fcsr, 0); // initialize rounding mode, undefined at reset
}
#endif
}
void _fini()
{
}
