greybus: tracepoints: Add standard Linux tracepoint for TimeSync event

This patch adds a tracepoint to the TimeSync ISR, the purpose of which is
to indicate a TimeSync event has happened. This tracepoint can be enabled
by issuing the following command:

echo 1 > /sys/kernel/debug/tracing/events/greybus/gb_timesync_irq/enable

Synchronization looks like this:

 TIMESTAMP  FUNCTION
    |         |
147.865788: gb_timesync_irq: strobe 1/4 frame-time 2910076529
147.866781: gb_timesync_irq: strobe 2/4 frame-time 2910095689
147.867777: gb_timesync_irq: strobe 3/4 frame-time 2910114820
147.868791: gb_timesync_irq: strobe 4/4 frame-time 2910134038

A ping can be triggered like this:

cat /sys/kernel/debug/greybus/frame-time

And that ping looks like this:

 TIMESTAMP  FUNCTION
    |         |
147.934678: gb_timesync_irq: ping 4/4 frame-time 2911380356
169.280551: gb_timesync_irq: ping 4/4 frame-time 3321221069

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Reviewed-by: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
Acked-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

diff --git a/drivers/staging/greybus/greybus_trace.h b/drivers/staging/greybus/greybus_trace.h
index 342f5adb67087795b6604240dd68da880b3a5de8..7249b8aba583ac29a7cc5669ba22de54343f0f2b 100644 (file)
--- a/drivers/staging/greybus/greybus_trace.h
+++ b/drivers/staging/greybus/greybus_trace.h
@@ -488,6 +488,34 @@ DEFINE_HD_EVENT(gb_hd_in);
 
 #undef DEFINE_HD_EVENT
 
+/*
+ * Occurs on a TimeSync synchronization event or a TimeSync ping event.
+ */
+TRACE_EVENT(gb_timesync_irq,
+
+       TP_PROTO(u8 ping, u8 strobe, u8 count, u64 frame_time),
+
+       TP_ARGS(ping, strobe, count, frame_time),
+
+       TP_STRUCT__entry(
+               __field(u8, ping)
+               __field(u8, strobe)
+               __field(u8, count)
+               __field(u64, frame_time)
+       ),
+
+       TP_fast_assign(
+               __entry->ping = ping;
+               __entry->strobe = strobe;
+               __entry->count = count;
+               __entry->frame_time = frame_time;
+       ),
+
+       TP_printk("%s %d/%d frame-time %llu\n",
+                 __entry->ping ? "ping" : "strobe", __entry->strobe,
+                 __entry->count, __entry->frame_time)
+);
+
 #endif /* _TRACE_GREYBUS_H */
 
 /* This part must be outside protection */

diff --git a/drivers/staging/greybus/timesync.c b/drivers/staging/greybus/timesync.c
index 260b670596bbf36c1f140e00600a8416045393b4..4bf62adf4f7a1f54d94b0f4ae8ed1b99188fb0f6 100644 (file)
--- a/drivers/staging/greybus/timesync.c
+++ b/drivers/staging/greybus/timesync.c
@@ -9,6 +9,7 @@
 #include <linux/debugfs.h>
 #include "greybus.h"
 #include "timesync.h"
+#include "greybus_trace.h"
 
 /*
  * Minimum inter-strobe value of one millisecond is chosen because it
@@ -974,17 +975,19 @@ void gb_timesync_irq(struct gb_timesync_svc *timesync_svc)
 {
        unsigned long flags;
        u64 strobe_time;
+       bool strobe_is_ping = true;
 
        strobe_time = __gb_timesync_get_frame_time(timesync_svc);
 
        spin_lock_irqsave(&timesync_svc->spinlock, flags);
 
        if (timesync_svc->state == GB_TIMESYNC_STATE_PING) {
-               if (timesync_svc->capture_ping)
-                       timesync_svc->ap_ping_frame_time = strobe_time;
-               goto done;
+               if (!timesync_svc->capture_ping)
+                       goto done_nolog;
+               timesync_svc->ap_ping_frame_time = strobe_time;
+               goto done_log;
        } else if (timesync_svc->state != GB_TIMESYNC_STATE_WAIT_SVC) {
-               goto done;
+               goto done_nolog;
        }
 
        timesync_svc->strobe_time[timesync_svc->strobe] = strobe_time;
@@ -993,7 +996,11 @@ void gb_timesync_irq(struct gb_timesync_svc *timesync_svc)
                gb_timesync_set_state(timesync_svc,
                                      GB_TIMESYNC_STATE_AUTHORITATIVE);
        }
-done:
+       strobe_is_ping = false;
+done_log:
+       trace_gb_timesync_irq(strobe_is_ping, timesync_svc->strobe,
+                             GB_TIMESYNC_MAX_STROBES, strobe_time);
+done_nolog:
        spin_unlock_irqrestore(&timesync_svc->spinlock, flags);
 }
 EXPORT_SYMBOL(gb_timesync_irq);