greybus: timesync: Add debugfs entry to display frame-ping in ktime

This patch makes a debugfs entry in
/sys/kernel/debug/greybus/X-svc/frame-ktime that generates a TimeSync ping
event to the system and then subsequently presents that data to user-space
as a ktime/timespec clock-monotonic value rather than as a raw frame-time,
to aid humans in debugging and understanding frame-time and to provide an
example of the converting a frame-time to timespec/ktime to other
developers.

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

diff --git a/drivers/staging/greybus/timesync.c b/drivers/staging/greybus/timesync.c
index ebc61ef..87cbe10 100644 (file)
--- a/drivers/staging/greybus/timesync.c
+++ b/drivers/staging/greybus/timesync.c
@@ -69,6 +69,7 @@ struct gb_timesync_svc {
        struct mutex mutex;     /* Per SVC mutex for regular synchronization */
 
        struct dentry *frame_time_dentry;
+       struct dentry *frame_ktime_dentry;
        struct workqueue_struct *work_queue;
        wait_queue_head_t wait_queue;
        struct delayed_work delayed_work;
@@ -506,6 +507,7 @@ static int gb_timesync_to_timespec(struct gb_timesync_svc *timesync_svc,
        bool add;
        int ret = 0;
 
+       memset(ts, 0x00, sizeof(*ts));
        mutex_lock(&timesync_svc->mutex);
        spin_lock_irqsave(&timesync_svc->spinlock, flags);
 
@@ -575,7 +577,6 @@ static size_t gb_timesync_log_frame_time(struct gb_timesync_svc *timesync_svc,
        size_t off;
 
        /* AP/SVC */
-       memset(buf, 0x00, buflen);
        off = snprintf(buf, buflen, "timesync: ping-time ap=%llu %s=%llu ",
                       timesync_svc->ap_ping_frame_time, dev_name(&svc->dev),
                       timesync_svc->svc_ping_frame_time);
@@ -604,6 +605,65 @@ static size_t gb_timesync_log_frame_time(struct gb_timesync_svc *timesync_svc,
        return off;
 }
 
+static size_t gb_timesync_log_frame_ktime(struct gb_timesync_svc *timesync_svc,
+                                         char *buf, size_t buflen)
+{
+       struct gb_svc *svc = timesync_svc->svc;
+       struct gb_host_device *hd;
+       struct gb_timesync_interface *timesync_interface;
+       struct gb_interface *interface;
+       struct timespec ts;
+       unsigned int len;
+       size_t off;
+
+       /* AP */
+       gb_timesync_to_timespec(timesync_svc, timesync_svc->ap_ping_frame_time,
+                               &ts);
+       off = snprintf(buf, buflen, "timesync: ping-time ap=%lu.%lu ",
+                      ts.tv_sec, ts.tv_nsec);
+       len = buflen - off;
+       if (len >= buflen)
+               goto done;
+
+       /* SVC */
+       gb_timesync_to_timespec(timesync_svc, timesync_svc->svc_ping_frame_time,
+                               &ts);
+       off += snprintf(&buf[off], len, "%s=%lu.%lu ", dev_name(&svc->dev),
+                       ts.tv_sec, ts.tv_nsec);
+       len = buflen - off;
+       if (len >= buflen)
+               goto done;
+
+       /* APB/GPB */
+       hd = timesync_svc->timesync_hd->hd;
+       gb_timesync_to_timespec(timesync_svc,
+                               timesync_svc->timesync_hd->ping_frame_time,
+                               &ts);
+       off += snprintf(&buf[off], len, "%s=%lu.%lu ",
+                       dev_name(&hd->dev),
+                       ts.tv_sec, ts.tv_nsec);
+       len = buflen - off;
+       if (len >= buflen)
+               goto done;
+
+       list_for_each_entry(timesync_interface,
+                           &timesync_svc->interface_list, list) {
+               interface = timesync_interface->interface;
+               gb_timesync_to_timespec(timesync_svc,
+                                       timesync_interface->ping_frame_time,
+                                       &ts);
+               off += snprintf(&buf[off], len, "%s=%lu.%lu ",
+                               dev_name(&interface->dev),
+                               ts.tv_sec, ts.tv_nsec);
+               len = buflen - off;
+               if (len >= buflen)
+                       goto done;
+       }
+       off += snprintf(&buf[off], len, "\n");
+done:
+       return off;
+}
+
 /*
  * Send an SVC initiated wake 'ping' to each TimeSync participant.
  * Get the FrameTime from each participant associated with the wake
@@ -840,11 +900,11 @@ done:
 }
 EXPORT_SYMBOL_GPL(gb_timesync_schedule_asynchronous);
 
-static ssize_t gb_timesync_ping_read(struct file *file, char __user *buf,
-                                    size_t len, loff_t *offset)
+static ssize_t gb_timesync_ping_read(struct file *file, char __user *ubuf,
+                                    size_t len, loff_t *offset, bool ktime)
 {
        struct gb_timesync_svc *timesync_svc = file->f_inode->i_private;
-       char *pbuf;
+       char *buf;
        ssize_t ret = 0;
 
        mutex_lock(&gb_timesync_svc_list_mutex);
@@ -861,23 +921,44 @@ static ssize_t gb_timesync_ping_read(struct file *file, char __user *buf,
        if (ret)
                goto done;
 
-       pbuf = kzalloc(PAGE_SIZE, GFP_KERNEL);
-       if (!pbuf) {
+       buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
+       if (!buf) {
                ret = -ENOMEM;
                goto done;
        }
 
-       ret = gb_timesync_log_frame_time(timesync_svc, pbuf, PAGE_SIZE);
+       if (ktime)
+               ret = gb_timesync_log_frame_ktime(timesync_svc, buf, PAGE_SIZE);
+       else
+               ret = gb_timesync_log_frame_time(timesync_svc, buf, PAGE_SIZE);
        if (ret > 0)
-               ret = simple_read_from_buffer(buf, len, offset, pbuf, ret);
-       kfree(pbuf);
+               ret = simple_read_from_buffer(ubuf, len, offset, buf, ret);
+       kfree(buf);
 done:
        mutex_unlock(&gb_timesync_svc_list_mutex);
        return ret;
 }
 
-static const struct file_operations gb_timesync_debugfs_ops = {
-       .read           = gb_timesync_ping_read,
+static ssize_t gb_timesync_ping_read_frame_time(struct file *file,
+                                               char __user *buf,
+                                               size_t len, loff_t *offset)
+{
+       return gb_timesync_ping_read(file, buf, len, offset, false);
+}
+
+static ssize_t gb_timesync_ping_read_frame_ktime(struct file *file,
+                                                char __user *buf,
+                                                size_t len, loff_t *offset)
+{
+       return gb_timesync_ping_read(file, buf, len, offset, true);
+}
+
+static const struct file_operations gb_timesync_debugfs_frame_time_ops = {
+       .read           = gb_timesync_ping_read_frame_time,
+};
+
+static const struct file_operations gb_timesync_debugfs_frame_ktime_ops = {
+       .read           = gb_timesync_ping_read_frame_ktime,
 };
 
 static int gb_timesync_hd_add(struct gb_timesync_svc *timesync_svc,
@@ -935,13 +1016,21 @@ int gb_timesync_svc_add(struct gb_svc *svc)
        timesync_svc->frame_time_offset = 0;
        timesync_svc->capture_ping = false;
        gb_timesync_set_state_atomic(timesync_svc, GB_TIMESYNC_STATE_INACTIVE);
+
        timesync_svc->frame_time_dentry =
                debugfs_create_file("frame-time", S_IRUGO, svc->debugfs_dentry,
-                                   timesync_svc, &gb_timesync_debugfs_ops);
+                                   timesync_svc,
+                                   &gb_timesync_debugfs_frame_time_ops);
+       timesync_svc->frame_ktime_dentry =
+               debugfs_create_file("frame-ktime", S_IRUGO, svc->debugfs_dentry,
+                                   timesync_svc,
+                                   &gb_timesync_debugfs_frame_ktime_ops);
+
        list_add(&timesync_svc->list, &gb_timesync_svc_list);
        ret = gb_timesync_hd_add(timesync_svc, svc->hd);
        if (ret) {
                list_del(&timesync_svc->list);
+               debugfs_remove(timesync_svc->frame_ktime_dentry);
                debugfs_remove(timesync_svc->frame_time_dentry);
                destroy_workqueue(timesync_svc->work_queue);
                kfree(timesync_svc);
@@ -982,6 +1071,7 @@ void gb_timesync_svc_remove(struct gb_svc *svc)
                kfree(timesync_interface);
        }
        gb_timesync_set_state_atomic(timesync_svc, GB_TIMESYNC_STATE_INVALID);
+       debugfs_remove(timesync_svc->frame_ktime_dentry);
        debugfs_remove(timesync_svc->frame_time_dentry);
        cancel_delayed_work_sync(&timesync_svc->delayed_work);
        destroy_workqueue(timesync_svc->work_queue);