[PATCH] bsp/leon3: Use interrupt timestamping counter

[Sebastian Huber]

Use the interrupt controller timestamping counter for the CPU counter if
available since it runs with a high frequency.
---
 c/src/lib/libbsp/sparc/leon3/include/leon.h       |    7 ++
 c/src/lib/libbsp/sparc/leon3/startup/cpucounter.c |   90 +++++++++++++++------
 2 files changed, 71 insertions(+), 26 deletions(-)

diff --git a/c/src/lib/libbsp/sparc/leon3/include/leon.h b/c/src/lib/libbsp/sparc/leon3/include/leon.h
index 476ed5c..2887091 100644
--- a/c/src/lib/libbsp/sparc/leon3/include/leon.h
+++ b/c/src/lib/libbsp/sparc/leon3/include/leon.h
@@ -399,6 +399,13 @@ static inline uint32_t leon3_get_data_cache_config_register(void)
   return leon3_get_system_register(0xc);
 }
 
+static bool leon3_irqmp_has_timestamp(
+  volatile struct irqmp_timestamp_regs *irqmp_ts
+)
+{
+  return (irqmp_ts->control >> 27) > 0;
+}
+
 #endif /* !ASM */
 
 #ifdef __cplusplus
diff --git a/c/src/lib/libbsp/sparc/leon3/startup/cpucounter.c b/c/src/lib/libbsp/sparc/leon3/startup/cpucounter.c
index 44faf92..b975e1c 100644
--- a/c/src/lib/libbsp/sparc/leon3/startup/cpucounter.c
+++ b/c/src/lib/libbsp/sparc/leon3/startup/cpucounter.c
@@ -21,6 +21,14 @@ static volatile struct gptimer_regs *adev_to_gpt(struct ambapp_dev *adev)
   return (volatile struct gptimer_regs *) DEV_TO_APB(adev)->start;
 }
 
+static CPU_Counter_ticks timestamp_counter_difference(
+  CPU_Counter_ticks second,
+  CPU_Counter_ticks first
+)
+{
+  return second - first;
+}
+
 static CPU_Counter_ticks free_counter_difference(
   CPU_Counter_ticks second,
   CPU_Counter_ticks first
@@ -54,39 +62,69 @@ static void gpt_counter_initialize(
   rtems_counter_initialize_converter(frequency);
 }
 
+static unsigned int get_tstamp(volatile struct irqmp_timestamp_regs *irqmp_ts)
+{
+  return irqmp_ts->control >> 27;
+}
+
 void leon3_cpu_counter_initialize(void)
 {
+  volatile struct irqmp_timestamp_regs *irqmp_ts =
+    &LEON3_IrqCtrl_Regs->timestamp[0];
   struct ambapp_dev *adev;
   int idx = 1;
 
-  adev = (void *) ambapp_for_each(
-    &ambapp_plb,
-    OPTIONS_ALL | OPTIONS_APB_SLVS,
-    VENDOR_GAISLER,
-    GAISLER_GPTIMER,
-    ambapp_find_by_idx,
-    &idx
-  );
-  if (adev != NULL) {
-    /* Use the second GPTIMER if available */
-    volatile struct gptimer_regs *gpt = adev_to_gpt(adev);
-    uint32_t max_frequency = ambapp_freq_get(&ambapp_plb, adev);
-    unsigned min_prescaler = 8;
-    uint32_t frequency = max_frequency / min_prescaler;
+  if (leon3_irqmp_has_timestamp(irqmp_ts)) {
+    /* Use the interrupt controller timestamp counter if available */
 
-    gpt->scaler_reload = min_prescaler - 1;
-    gpt->timer[0].reload = 0xffffffff;
-    gpt->timer[0].ctrl = LEON3_GPTIMER_EN | LEON3_GPTIMER_RL
-      | LEON3_GPTIMER_LD;
+    /* Enable interrupt timestamping for an arbitrary interrupt line */
+    irqmp_ts->control = 0x1;
+
+    _SPARC_Counter_initialize(
+      (volatile const uint32_t *) &irqmp_ts->counter,
+      timestamp_counter_difference
+    );
 
-    gpt_counter_initialize(gpt, 0, frequency, free_counter_difference);
-  } else if (LEON3_Timer_Regs != NULL) {
-    /* Fall back to the first GPTIMER if available */
-    gpt_counter_initialize(
-      LEON3_Timer_Regs,
-      LEON3_CLOCK_INDEX,
-      LEON3_GPTIMER_0_FREQUENCY_SET_BY_BOOT_LOADER,
-      clock_counter_difference
+    /* Get and set the frequency */
+    adev = (void *) ambapp_for_each(
+      &ambapp_plb,
+      OPTIONS_ALL | OPTIONS_APB_SLVS,
+      VENDOR_GAISLER,
+      GAISLER_IRQMP,
+      ambapp_find_by_idx,
+      NULL
     );
+    rtems_counter_initialize_converter(ambapp_freq_get(&ambapp_plb, adev));
+  } else {
+    adev = (void *) ambapp_for_each(
+      &ambapp_plb,
+      OPTIONS_ALL | OPTIONS_APB_SLVS,
+      VENDOR_GAISLER,
+      GAISLER_GPTIMER,
+      ambapp_find_by_idx,
+      &idx
+    );
+    if (adev != NULL) {
+      /* Use the second GPTIMER if available */
+      volatile struct gptimer_regs *gpt = adev_to_gpt(adev);
+      uint32_t max_frequency = ambapp_freq_get(&ambapp_plb, adev);
+      unsigned min_prescaler = 8;
+      uint32_t frequency = max_frequency / min_prescaler;
+
+      gpt->scaler_reload = min_prescaler - 1;
+      gpt->timer[0].reload = 0xffffffff;
+      gpt->timer[0].ctrl = LEON3_GPTIMER_EN | LEON3_GPTIMER_RL
+        | LEON3_GPTIMER_LD;
+
+      gpt_counter_initialize(gpt, 0, frequency, free_counter_difference);
+    } else if (LEON3_Timer_Regs != NULL) {
+      /* Fall back to the first GPTIMER if available */
+      gpt_counter_initialize(
+        LEON3_Timer_Regs,
+        LEON3_CLOCK_INDEX,
+        LEON3_GPTIMER_0_FREQUENCY_SET_BY_BOOT_LOADER,
+        clock_counter_difference
+      );
+    }
   }
 }
-- 
1.7.7