HiFive1 AON Watchdog example

3 files changed, 231 insertions, 0 deletions

diff --git a/software/watchdog/.gitignore b/software/watchdog/.gitignore
new file mode 100644
index 0000000..35566c7
--- /dev/null
+++ b/software/watchdog/.gitignore
@@ -0,0 +1 @@
+demo_gpio
diff --git a/software/watchdog/Makefile b/software/watchdog/Makefile
new file mode 100644
index 0000000..f614a4e
--- /dev/null
+++ b/software/watchdog/Makefile
@@ -0,0 +1,9 @@
+TARGET = watchdog
+CFLAGS += -O2 -fno-builtin-printf -DUSE_PLIC -DUSE_M_TIME
+
+BSP_BASE = ../../bsp
+
+C_SRCS += watchdog.c
+C_SRCS += $(BSP_BASE)/drivers/plic/plic_driver.c
+
+include $(BSP_BASE)/env/common.mk
diff --git a/software/watchdog/watchdog.c b/software/watchdog/watchdog.c
new file mode 100644
index 0000000..672ed68
--- /dev/null
+++ b/software/watchdog/watchdog.c
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+// 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>
+#include "stdatomic.h"
+
+void reset_demo (void);
+
+// Structures for registering different interrupt handlers
+// for different parts of the application.
+typedef void (*function_ptr_t) (void);
+void no_interrupt_handler (void) {};
+function_ptr_t g_ext_interrupt_handlers[PLIC_NUM_INTERRUPTS];
+
+
+// Instance data for the PLIC.
+plic_instance_t g_plic;
+
+
+/**
+* use mtime to wait for a specified number of ticks.
+* async determins if this is a busy wait, or if
+* an irq is scheduled
+*/
+void mtime_wait( uint64_t ticks, uint32_t async)
+{
+
+    volatile uint64_t * mtime  = (uint64_t*) (CLINT_CTRL_ADDR + CLINT_MTIME);
+    uint64_t now = *mtime;
+    
+    //if async, schedule irq
+    if(async) {
+      volatile uint64_t * mtimecmp = (uint64_t*) (CLINT_CTRL_ADDR + CLINT_MTIMECMP);
+      uint64_t then = now + ticks; 
+      *mtimecmp = then;
+      set_csr(mie, MIP_MTIP);
+
+    } else  {
+      //else busy wait
+      uint64_t then = now + ticks;
+      while(*mtime<then) {}
+
+    }
+
+}
+
+/*Entry Point for PLIC Interrupt Handler*/
+void handle_m_ext_interrupt(){
+  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);
+}
+
+//global countdown timer
+static uint32_t countdown = 10;
+/*Entry Point for Machine Timer Interrupt Handler*/
+void handle_m_time_interrupt(){
+
+  //cleare the timer irq
+  clear_csr(mie, MIP_MTIP);
+
+  //schedule next timer irq for 1 second
+  mtime_wait(1*RTC_FREQ, 1);
+
+  //flash a led
+  GPIO_REG(GPIO_OUTPUT_VAL) ^=	(0x1 << BLUE_LED_OFFSET);
+  
+  //print the count
+  printf("watchdog reset in %d\n", countdown--);
+}
+
+
+const char * instructions_msg = " \
+\n\
+                SIFIVE, INC.\n\
+\n\
+         5555555555555555555555555\n\
+        5555                   5555\n\
+       5555                     5555\n\
+      5555                       5555\n\
+     5555       5555555555555555555555\n\
+    5555       555555555555555555555555\n\
+   5555                             5555\n\
+  5555                               5555\n\
+ 5555                                 5555\n\
+5555555555555555555555555555          55555\n\
+ 55555           555555555           55555\n\
+   55555           55555           55555\n\
+     55555           5           55555\n\
+       55555                   55555\n\
+         55555               55555\n\
+           55555           55555\n\
+             55555       55555\n\
+               55555   55555\n\
+                 555555555\n\
+                   55555\n\
+                     5\n\
+\n\
+This application demonstrates the functionality of\n\
+the watchdog timer present in the HiFive1 AON peripheral.\n\
+\n\
+The Watchdog timer will expire in 10 seconds resulting in\n\
+a software reset.\n\
+\n\
+Press a key to prevent a reset\n\
+";
+
+void print_instructions() {
+
+  write (STDOUT_FILENO, instructions_msg, strlen(instructions_msg));
+
+}
+
+
+/**
+* Flash the red led for a second, then set up
+* blue for blinking during mtime irq
+*/
+void led_init() {
+
+
+  // Set up the GPIOs such that the LED GPIO
+  // can be used as both Inputs and Outputs.
+  GPIO_REG(GPIO_INPUT_EN)    &= ~((0x1<< RED_LED_OFFSET) | (0x1<< GREEN_LED_OFFSET) | (0x1 << BLUE_LED_OFFSET)) ;
+  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));
+
+  //flash red led to indicate reset
+  GPIO_REG(GPIO_OUTPUT_VAL)  &=   ~(0x1 << RED_LED_OFFSET) ;
+  mtime_wait(1*RTC_FREQ,0);
+  GPIO_REG(GPIO_OUTPUT_VAL)  |=   (0x1 << RED_LED_OFFSET) ;
+}
+
+/**
+* initialize the watchdog to reset in
+* 5 seconds
+**/
+void watchdog_init()  {
+
+
+//reset in 10 seconds
+AON_REG(AON_WDOGKEY) = AON_WDOGKEY_VALUE;
+AON_REG(AON_WDOGCMP) = 11;
+//wdogconfig: : wdogrsten | enablealways | reset to 0 | max scale
+AON_REG(AON_WDOGKEY) = AON_WDOGKEY_VALUE;
+AON_REG(AON_WDOGCFG) |= (AON_WDOGCFG_RSTEN | AON_WDOGCFG_ENALWAYS |\
+                        AON_WDOGCFG_ZEROCMP | AON_WDOGCFG_SCALE) ;
+
+}
+
+void reset_demo ()  {
+
+  // Disable the machine & timer interrupts until setup is done.
+  clear_csr(mie, MIP_MEIP);
+  clear_csr(mie, MIP_MTIP);
+
+  //enable uart input
+  UART0_REG(UART_REG_RXCTRL) = UART_RXEN;
+
+  /**************************************************************************
+   * Set up the PLIC
+   *************************************************************************/
+  PLIC_init(&g_plic,
+	    PLIC_CTRL_ADDR,
+	    PLIC_NUM_INTERRUPTS,
+	    PLIC_NUM_PRIORITIES);
+
+  for (int ii = 0; ii < PLIC_NUM_INTERRUPTS; ii ++){
+    g_ext_interrupt_handlers[ii] = no_interrupt_handler;
+  }
+
+
+  led_init();
+  print_instructions();
+  watchdog_init();
+  
+  // Enable the Machine-External bit in MIE
+  set_csr(mie, MIP_MEIP);
+  // Enable interrupts in general.
+  set_csr(mstatus, MSTATUS_MIE);
+}
+
+int main(int argc, char **argv)
+{
+
+  reset_demo();
+  //schedule a 1 second timer 
+  mtime_wait(1*RTC_FREQ,1);
+
+ 
+  while (1){
+    char c;
+    if(((int32_t) UART0_REG(UART_REG_RXFIFO)) > 0){
+        //flash green led to indicate Kick
+        GPIO_REG(GPIO_OUTPUT_VAL)  &=   ~(0x1 << GREEN_LED_OFFSET) ;  
+
+        printf("Feeding Watchdog.\nHiFive1 will reset in 10 seconds.\n");
+        countdown = 10;
+        AON_REG(AON_WDOGKEY) = AON_WDOGKEY_VALUE;
+        AON_REG(AON_WDOGFEED) = AON_WDOGFEED_VALUE;
+
+        //busy wait a bit so the user sees the led blink
+        mtime_wait(5000, 0);
+        //turn off led
+        GPIO_REG(GPIO_OUTPUT_VAL)  |=   (0x1 << GREEN_LED_OFFSET) ;
+    }
+  }
+
+  return 0;
+
+}