From e008ed03839d46388f184206d634021fd083dc78 Mon Sep 17 00:00:00 2001
From: Drew Barbier <dbarbi1@gmail.com>
Date: Wed, 26 Jul 2017 14:55:16 -0500
Subject: only save/restore "caller" registers on trap entry

---
 .../vectored_interrupts/vectored_interrupts.c      | 216 +++++++++++++++++++++
 1 file changed, 216 insertions(+)
 create mode 100644 FreedomStudio/E31FPGA/vectored_interrupts/vectored_interrupts.c

(limited to 'FreedomStudio/E31FPGA')

diff --git a/FreedomStudio/E31FPGA/vectored_interrupts/vectored_interrupts.c b/FreedomStudio/E31FPGA/vectored_interrupts/vectored_interrupts.c
new file mode 100644
index 0000000..8958105
--- /dev/null
+++ b/FreedomStudio/E31FPGA/vectored_interrupts/vectored_interrupts.c
@@ -0,0 +1,216 @@
+// See LICENSE for license details.
+
+#include <stdio.h>
+#include <stdlib.h>
+#include "platform.h"
+#include <string.h>
+#include "plic/plic_driver.h"
+#include "encoding.h"
+#include <unistd.h>
+
+#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;
+
+// Structures for registering different interrupt handlers
+// for different parts of the application.
+typedef void (*interrupt_function_ptr_t) (void);
+//array of function pointers which contains the PLIC
+//interrupt handlers
+interrupt_function_ptr_t g_ext_interrupt_handlers[PLIC_NUM_INTERRUPTS];
+
+const char * instructions_msg = " \
+\n\
+                SIFIVE, INC.\n\
+E31/E51 Coreplex IP Eval Kit 'vectored_interrupts' demo.  \n\
+\n\
+This demo demonstrates Vectored Interrupts capabilities of\n\
+the E31/E51 Coreplex. The vector table is defined in      \n\
+bsp/env/ventry.S                                          \n\
+Button 0 is a global external interrupt routed to the PLIC.\n\
+Button 1 is a local interrupt.\n\
+\n";
+
+void print_instructions() {
+
+  write (STDOUT_FILENO, instructions_msg, strlen(instructions_msg));
+
+}
+
+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 + 1*RTC_FREQ;
+  *mtimecmp = then;
+
+  set_csr(mie, MIP_MTIP);
+}
+
+/*Entry Point for Machine Timer Interrupt Handler*/
+/*called from bsp/env/ventry.s          */
+void handle_m_time_interrupt(){
+  static uint32_t onoff=1;
+
+  clear_csr(mie, MIP_MTIP);
+
+  // Set Green LED
+  if(onoff)	{
+	  GPIO_REG(GPIO_OUTPUT_VAL)  |=  (0x1 << GREEN_LED_OFFSET) ;
+	  onoff=0;
+  }else	{
+	  GPIO_REG(GPIO_OUTPUT_VAL)  &=  ~((0x1 << GREEN_LED_OFFSET)) ;
+	  onoff=1;
+  }
+  set_timer();
+
+  //re-enable button1 irq
+  set_csr(mie, MIP_MLIP(LOCAL_INT_BTN_1));
+
+}
+
+/*Synchronous Trap Handler*/
+/*called from bsp/env/ventry.s          */
+void handle_sync_trap(uintptr_t mcause, uintptr_t epc ) {
+    write(1, "vUnhandled Trap:\n", 16);
+    _exit(1 + mcause);
+}
+
+/*Entry Point for PLIC Interrupt Handler*/
+/*called from bsp/env/ventry.s          */
+void handle_m_external_interrupt(){
+  printf("In PLIC handler\n");
+  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);
+}
+
+//default empty PLIC handler
+void invalid_global_isr() {
+  printf("Unexpected global interrupt!\n");
+}
+
+/* b0 global interrupt isr                */
+/*called from handle_m_external_interrupt */
+void button_0_handler() {
+  static uint32_t onoff=1;
+  // Set Green LED
+
+  printf("In Button 0 handler\n");
+
+  if(onoff)	{
+	  GPIO_REG(GPIO_OUTPUT_VAL)  |=  (0x1 << BLUE_LED_OFFSET) ;
+	  onoff=0;
+  }else	{
+	  GPIO_REG(GPIO_OUTPUT_VAL)  &=  ~((0x1 << BLUE_LED_OFFSET)) ;
+	  onoff=1;
+  }
+
+  //clear irq - interrupt pending register is write 1 to clear
+  GPIO_REG(GPIO_FALL_IP) |= (1<<BUTTON_0_OFFSET);
+}
+
+/*b1 local vectored irq handler         */
+/*called from bsp/env/ventry.s          */
+void handle_local_interrupt5() {
+  static uint32_t onoff=1;
+  // Set Green LED
+
+  printf("In Button 1 handler\n");
+
+  if(onoff)	{
+	  GPIO_REG(GPIO_OUTPUT_VAL)  |=  (0x1 << RED_LED_OFFSET) ;
+	  onoff=0;
+  }else	{
+	  GPIO_REG(GPIO_OUTPUT_VAL)  &=  ~((0x1 << RED_LED_OFFSET)) ;
+	  onoff=1;
+  }
+
+  //debounce by turning off until next timer tick
+  clear_csr(mie, MIP_MLIP(LOCAL_INT_BTN_1));
+}
+
+/*configures Button0 as a global gpio irq*/
+void b0_irq_init()  {
+
+    //dissable hw io function
+    GPIO_REG(GPIO_IOF_EN )    &=  ~(1 << BUTTON_0_OFFSET);
+
+    //set to input
+    GPIO_REG(GPIO_INPUT_EN)   |= (1<<BUTTON_0_OFFSET);
+    GPIO_REG(GPIO_PULLUP_EN)  |= (1<<BUTTON_0_OFFSET);
+
+    //set to interrupt on falling edge
+    GPIO_REG(GPIO_FALL_IE)    |= (1<<BUTTON_0_OFFSET);
+
+    PLIC_init(&g_plic,
+  	    PLIC_CTRL_ADDR,
+  	    PLIC_NUM_INTERRUPTS,
+  	    PLIC_NUM_PRIORITIES);
+
+    PLIC_enable_interrupt (&g_plic, INT_DEVICE_BUTTON_0);
+    PLIC_set_priority(&g_plic, INT_DEVICE_BUTTON_0, 2);
+    g_ext_interrupt_handlers[INT_DEVICE_BUTTON_0] = button_0_handler;
+}
+
+/*configures Button1 as a local interrupt*/
+void b1_irq_init()  {
+
+    //enable the interrupt
+    set_csr(mie, MIP_MLIP(LOCAL_INT_BTN_1));
+
+}
+
+/*turn down the brightness, and configure GPIO */
+void led_init() {
+  // 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;
+  // Set up RGB LEDs for a visual.
+  GPIO_REG(GPIO_OUTPUT_EN)   |=  ((0x1<< RED_LED_OFFSET)| (0x1<< GREEN_LED_OFFSET)| (0x1<< BLUE_LED_OFFSET));
+  GPIO_REG(GPIO_OUTPUT_VAL)  &=  ~((0x1<< RED_LED_OFFSET) | (0x1<< GREEN_LED_OFFSET) | (0x1<< BLUE_LED_OFFSET));
+
+}
+
+int main(int argc, char **argv)
+{
+  //setup default global interrupt handler
+  for (int gisr = 0; gisr < PLIC_NUM_INTERRUPTS; gisr++){
+    g_ext_interrupt_handlers[PLIC_NUM_INTERRUPTS] = invalid_global_isr;
+  }
+  
+  print_instructions();
+  
+  led_init();
+  b0_irq_init();
+  b1_irq_init();
+
+  // Set up machine timer interrupt.
+  set_timer();
+
+  // Enable Global (PLIC) interrupts.
+  set_csr(mie, MIP_MEIP);
+  
+  // Enable all interrupts
+  set_csr(mstatus, MSTATUS_MIE);
+
+
+  while(1){
+    asm volatile ("wfi");
+  }
+  
+  return 0;
+
+}
-- 
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