Regularize timing code

Provide get_timer_value() and get_timer_freq() and use them.  On Arty,
they use mcycle and the known-fixed core frequency, whereas on HiFive1
they use mtime and the known-fixed mtime frequency.

2 files changed, 23 insertions, 1 deletions

diff --git a/bsp/env/freedom-e300-arty/init.c b/bsp/env/freedom-e300-arty/init.c
index 0a80cbb..35b1104 100644
--- a/bsp/env/freedom-e300-arty/init.c
+++ b/bsp/env/freedom-e300-arty/init.c
@@ -9,11 +9,30 @@
 extern int main(int argc, char** argv);
 extern void trap_entry();
 
-uint32_t get_cpu_freq()
+static unsigned long get_cpu_freq()
 {
   return 65000000;
 }
 
+unsigned long get_timer_freq()
+{
+  return get_cpu_freq();
+}
+
+uint64_t get_timer_value()
+{
+#if __riscv_xlen == 32
+  while (1) {
+    uint32_t hi = read_csr(mcycleh);
+    uint32_t lo = read_csr(mcycle);
+    if (hi == read_csr(mcycleh))
+      return ((uint64_t)hi << 32) | lo;
+  }
+#else
+  return read_csr(mcycle);
+#endif
+}
+
 static void uart_init(size_t baud_rate)
 {
   GPIO_REG(GPIO_IOF_SEL) &= ~IOF0_UART0_MASK;
diff --git a/bsp/env/freedom-e300-arty/platform.h b/bsp/env/freedom-e300-arty/platform.h
index 1f62956..d5d6dda 100644
--- a/bsp/env/freedom-e300-arty/platform.h
+++ b/bsp/env/freedom-e300-arty/platform.h
@@ -119,4 +119,7 @@
 #define HAS_BOARD_BUTTONS
 #include "hifive1.h"
 
+unsigned long get_timer_freq(void);
+uint64_t get_timer_value(void);
+
 #endif /* _SIFIVE_PLATFORM_H */