net: ena: View PHC stats using debugfs

Add an entry named `phc_stats` to view the PHC statistics.
If PHC is enabled, the stats are printed, as below:

phc_cnt: 0
phc_exp: 0
phc_skp: 0
phc_err_dv: 0
phc_err_ts: 0

If PHC is disabled, no statistics will be displayed.

Signed-off-by: David Arinzon <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/ethernet/amazon/ena/ena_debugfs.c

···
 #include <linux/seq_file.h>
 #include <linux/pci.h>
 #include "ena_debugfs.h"
+#include "ena_phc.h"
+
+static int phc_stats_show(struct seq_file *file, void *priv)
+{
+	struct ena_adapter *adapter = file->private;
+
+	if (!ena_phc_is_active(adapter))
+		return 0;
+
+	seq_printf(file,
+		   "phc_cnt: %llu\n",
+		   adapter->ena_dev->phc.stats.phc_cnt);
+	seq_printf(file,
+		   "phc_exp: %llu\n",
+		   adapter->ena_dev->phc.stats.phc_exp);
+	seq_printf(file,
+		   "phc_skp: %llu\n",
+		   adapter->ena_dev->phc.stats.phc_skp);
+	seq_printf(file,
+		   "phc_err_dv: %llu\n",
+		   adapter->ena_dev->phc.stats.phc_err_dv);
+	seq_printf(file,
+		   "phc_err_ts: %llu\n",
+		   adapter->ena_dev->phc.stats.phc_err_ts);
+
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(phc_stats);
 
 void ena_debugfs_init(struct net_device *dev)
 {
···
 
 	adapter->debugfs_base =
 		debugfs_create_dir(dev_name(&adapter->pdev->dev), NULL);
+
+	debugfs_create_file("phc_stats",
+			    0400,
+			    adapter->debugfs_base,
+			    adapter,
+			    &phc_stats_fops);
 }
 
 void ena_debugfs_terminate(struct net_device *dev)