From 4d5cbec9118cbedf2d4ae5b54acaa22862245a4c Mon Sep 17 00:00:00 2001 From: Megan Wachs Date: Thu, 4 May 2017 05:46:05 -0700 Subject: Update SDK For E31/E51 Coreplex IP Evaluation --- software/global_interrupts/global_interrupts.c | 250 +++++++++++++++++++++++++ 1 file changed, 250 insertions(+) create mode 100644 software/global_interrupts/global_interrupts.c (limited to 'software/global_interrupts/global_interrupts.c') diff --git a/software/global_interrupts/global_interrupts.c b/software/global_interrupts/global_interrupts.c new file mode 100644 index 0000000..4d3a554 --- /dev/null +++ b/software/global_interrupts/global_interrupts.c @@ -0,0 +1,250 @@ +// See LICENSE for license details. + +#include +#include +#include "platform.h" +#include +#include "plic/plic_driver.h" +#include "encoding.h" +#include + +#ifndef _SIFIVE_COREPLEXIP_ARTY_H +#error 'global_interrupts' demo only supported for Coreplex IP Eval Kits +#endif + +// Global Instance data for the PLIC +// for use by the PLIC Driver. +plic_instance_t g_plic; + +// Flag for state +int g_switch1Wins; + +// Debounce counter (PWM can't go slow enough) +int g_debounce; + +void debounce(); + +// Structures for registering different interrupt handlers +// for different parts of the application. +typedef void (*interrupt_function_ptr_t) (void); + +// See bsp/env//init.c for how this +// interrupt vector is used. +interrupt_function_ptr_t localISR[32]; + +interrupt_function_ptr_t g_ext_interrupt_handlers[PLIC_NUM_INTERRUPTS]; + +void set_timer() { + + 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 + 10*RTC_FREQ; + *mtimecmp = then; + +} + +/*Entry Point for Machine Timer Interrupt Handler*/ +void mti_isr(){ + + if (g_switch1Wins) { + printf("#### Giving Switch 1 Priority for 10 seconds ####\n"); + // All other things being equal, lower IDs have + // higher priority. We have already set + // Switch 1 to priority 2 + // in the setup, so by giving these equal priority Switch 1 will win. + PLIC_set_priority(&g_plic, INT_EXT_DEVICE_SW_2, 2); + } else { + printf("**** Giving Switch 2 Priority for 10 seconds ****\n"); + // By setting Switch 2 a higher integer priority, it will win over switch 1. + PLIC_set_priority(&g_plic, INT_EXT_DEVICE_SW_2, 3); + } + g_switch1Wins ^= 0x1; + + set_timer(); + +} + +/*Entry Point for PLIC Interrupt Handler*/ +void mei_isr(){ + plic_source int_num = PLIC_claim_interrupt(&g_plic); + if ((int_num >=1 ) && (int_num < PLIC_NUM_INTERRUPTS)) { + g_ext_interrupt_handlers[int_num](); + } + else { + exit(1 + (uintptr_t) int_num); + } + PLIC_complete_interrupt(&g_plic, int_num); +} + +const char * instructions_msg = " \ +\n\ + SIFIVE, INC.\n\ +E31/E51 Coreplex IP Eval Kit 'global_interrupts' demo.\n\ +\n\ +Switches 1 and 2 are enabled as External Global Interrupts \n\ +(they don't go through the PLIC). You an observe priorities.\n\ +Priorities invert every few seconds, which is driven by the \n\ +PWM0 global interrupt. \n\ +\n"; + +void print_instructions() { + + write (STDOUT_FILENO, instructions_msg, strlen(instructions_msg)); + +} + +void invalid_global_isr() { + printf("Unexpected global interrupt!\n"); +} + +void invalid_local_isr() { + printf ("Unexpected local interrupt!\n"); +} + +void switch_1_handler() { + + printf("Switch 1 is on! Even if Switch 2 is on, Switch 1 must have higher priority right now.\n"); + + // Set Green LED + GPIO_REG(GPIO_OUTPUT_VAL) |= (0x1 << GREEN_LED_OFFSET) ; + GPIO_REG(GPIO_OUTPUT_VAL) &= ~((0x1<< RED_LED_OFFSET)); + + debounce(); + +} + +void switch_2_handler() { + printf("Switch 2 is on! Even if Switch 1 is on, Switch 2 must have higher priority right now.\n"); + + // Set RED LED + GPIO_REG(GPIO_OUTPUT_VAL) &= ~(0x1 << GREEN_LED_OFFSET) ; + GPIO_REG(GPIO_OUTPUT_VAL) |= (0x1<< RED_LED_OFFSET); + + debounce(); +} + +// We use PWM 0 as a +// timer interrupt for debouncing. + +void pwm_0_handler() { + + + if (g_debounce == 0) { + printf(" Done debouncing.\n"); + + //Lower the threshold s.t. the switches can hit. + PLIC_set_threshold(&g_plic, 1); + + // Clear the PWM interrupt + PWM0_REG(PWM_CFG) = 0; + + } else { + // Keep waiting + g_debounce --; + // This clears out the interrupt and re-arms the timer. + PWM0_REG(PWM_CFG) = ((PWM_CFG_ONESHOT) | (PWM_CFG_ZEROCMP)| 0x7 | (PWM_CFG_STICKY)); + + } + +} + +void debounce(int local_interrupt_num) { + + printf(" Starting a debounce.\n"); + + g_debounce = 600; + + // This clears out the interrupt and re-arms the timer. + PWM0_REG(PWM_CFG) = ((PWM_CFG_ONESHOT) | (PWM_CFG_ZEROCMP)| 0x7 | (PWM_CFG_STICKY)); + + // Set the threshold high enough that the + // switches won't cause the interrupt to fire, + // only the PWM or timer interrupts. + PLIC_set_threshold(&g_plic, 4); + +} + +int main(int argc, char **argv) +{ + + for (int gisr = 0; gisr < PLIC_NUM_INTERRUPTS; gisr++){ + g_ext_interrupt_handlers[PLIC_NUM_INTERRUPTS] = invalid_global_isr; + } + g_ext_interrupt_handlers[PWM0_INT_BASE + 0] = pwm_0_handler; + g_ext_interrupt_handlers[INT_EXT_DEVICE_SW_1] = switch_1_handler; + g_ext_interrupt_handlers[INT_EXT_DEVICE_SW_2] = switch_2_handler; + + for (int lisr = 0; lisr < 32; lisr++){ + localISR[lisr] = invalid_local_isr; + } + + localISR[IRQ_M_TIMER] = mti_isr; + localISR[IRQ_M_EXT] = mei_isr; + + print_instructions(); + + // Set up RGB LEDs for a visual. + + GPIO_REG(GPIO_OUTPUT_EN) |= ((0x1<< RED_LED_OFFSET)| (0x1<< GREEN_LED_OFFSET)); + GPIO_REG(GPIO_OUTPUT_VAL) |= (0x1 << GREEN_LED_OFFSET) ; + GPIO_REG(GPIO_OUTPUT_VAL) &= ~(0x1<< RED_LED_OFFSET); + + /************************************************************************** + * Set up the PLIC + * + *************************************************************************/ + PLIC_init(&g_plic, + PLIC_CTRL_ADDR, + PLIC_NUM_INTERRUPTS, + PLIC_NUM_PRIORITIES); + + /************************************************************************** + * Give Switch 1 and Switch 2 Equal priority of 2. + * + *************************************************************************/ + + PLIC_enable_interrupt (&g_plic, PWM0_INT_BASE + 0); + PLIC_enable_interrupt (&g_plic, INT_EXT_DEVICE_SW_1); + PLIC_enable_interrupt (&g_plic, INT_EXT_DEVICE_SW_2); + + // PWM always beats the switches, because we use it + // as a debouncer, and we lower the threshold + // to do so. + + PWM0_REG(PWM_CFG) = 0; + + // Make sure people aren't blinded by LEDs connected here. + PWM0_REG(PWM_CMP0) = 0xFE; + PWM0_REG(PWM_CMP1) = 0xFF; + PWM0_REG(PWM_CMP2) = 0xFF; + PWM0_REG(PWM_CMP3) = 0xFF; + PLIC_set_priority(&g_plic, PWM0_INT_BASE + 0 , 5); + + // Start the switches out at the same priority. Switch1 + // would win. + PLIC_set_priority(&g_plic, INT_EXT_DEVICE_SW_1, 2); + PLIC_set_priority(&g_plic, INT_EXT_DEVICE_SW_2, 2); + + // Set up machine timer interrupt. Every few seconds it + // will invert the switch priorities. + set_timer(); + + // Enable timer interrupts. + set_csr(mie, MIP_MTIP); + + // Enable Global (PLIC) interrupts. + set_csr(mie, MIP_MEIP); + + g_switch1Wins = 1; + + // Enable all interrupts + set_csr(mstatus, MSTATUS_MIE); + + while(1){ + asm volatile ("wfi"); + } + + return 0; + +} -- cgit v1.2.1-18-gbd029