scsi: hisi_sas: Add timestamp for a debugfs dump

It's useful to know when the dump occurred, so add a timestamp file for
this.

Link: https://lore.kernel.org/r/1571926105-74636-6-git-send-email-john.garry@huawei.comSigned-off-by: Luo Jiaxing <luojiaxing@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/hisi_sas/hisi_sas.h

@@ -21,6 +21,7 @@
 #include <linux/platform_device.h>
 #include <linux/property.h>
 #include <linux/regmap.h>
+#include <linux/timer.h>
 #include <scsi/sas_ata.h>
 #include <scsi/libsas.h>
 
@@ -410,6 +411,7 @@ struct hisi_hba {
 	struct hisi_sas_iost *debugfs_iost;
 	struct hisi_sas_itct *debugfs_itct;
 	u64 *debugfs_iost_cache;
+	u64 debugfs_timestamp;
 	u64 *debugfs_itct_cache;
 
 	struct dentry *debugfs_dir;

drivers/scsi/hisi_sas/hisi_sas_main.c

@@ -3194,6 +3194,7 @@ static const struct file_operations hisi_sas_debugfs_itct_cache_fops = {
 
 static void hisi_sas_debugfs_create_files(struct hisi_hba *hisi_hba)
 {
+	u64 *debugfs_timestamp;
 	struct dentry *dump_dentry;
 	struct dentry *dentry;
 	char name[256];
@@ -3201,10 +3202,14 @@ static void hisi_sas_debugfs_create_files(struct hisi_hba *hisi_hba)
 	int c;
 	int d;
 
+	debugfs_timestamp = &hisi_hba->debugfs_timestamp;
 	/* Create dump dir inside device dir */
 	dump_dentry = debugfs_create_dir("dump", hisi_hba->debugfs_dir);
 	hisi_hba->debugfs_dump_dentry = dump_dentry;
 
+	debugfs_create_u64("timestamp", 0400, dump_dentry,
+			   debugfs_timestamp);
+
 	debugfs_create_file("global", 0400, dump_dentry, hisi_hba,
 			    &hisi_sas_debugfs_global_fops);
 
@@ -3684,7 +3689,10 @@ void hisi_sas_debugfs_work_handler(struct work_struct *work)
 {
 	struct hisi_hba *hisi_hba =
 		container_of(work, struct hisi_hba, debugfs_work);
+	u64 timestamp = local_clock();
 
+	do_div(timestamp, NSEC_PER_MSEC);
+	hisi_hba->debugfs_timestamp = timestamp;
 	if (hisi_hba->debugfs_snapshot)
 		return;
 	hisi_hba->debugfs_snapshot = true;