scsi: hisi_sas: Add manual trigger for debugfs

Tester want to check some dump information sometimes
even though there is no error happened. So we add manual
trigger for this need.

Different with code, which used for upstream, I enable
mutil-dump here.
Signed-off-by: NLuo Jiaxing <luojiaxing@huawei.com>
Signed-off-by: NJohn Garry <john.garry@huawei.com>

Feature or Bugfix:Feature
Signed-off-by: Nluojiaxing <luojiaxing@huawei.com>
Reviewed-by: Nchenxiang <chenxiang66@hisilicon.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/scsi/hisi_sas/hisi_sas_main.c

@@ -3064,11 +3064,48 @@ static void hisi_sas_debugfs_snapshot_regs(struct hisi_hba *hisi_hba)
 	hisi_sas_debugfs_snapshot_itct_reg(hisi_hba);
 	hisi_sas_debugfs_snapshot_iost_reg(hisi_hba);
 
-	hisi_sas_debugfs_create_files(hisi_hba);
+	/* Avoid re-create files here */
+	if (!hisi_hba->debugfs_dump_dentry)
+		hisi_sas_debugfs_create_files(hisi_hba);
 
 	hisi_hba->hw->snapshot_restore(hisi_hba);
 }
 
+static ssize_t hisi_sas_debugfs_trigger_dump_write(struct file *file,
+						   const char __user *user_buf,
+						   size_t count,
+						   loff_t *ppos)
+{
+	struct hisi_hba *hisi_hba = file->f_inode->i_private;
+	u8 buf[8];
+
+	/*
+	 * The code, which used for upstream, check
+	 * the value of debugfs_snapshot here.
+	 * If not 0, will return -EFAULT.
+	 * Keep manual dump as one time only
+	 */
+
+	/* Not allow to input more than 8 char */
+	if (count > 8)
+		return -EFAULT;
+
+	if (copy_from_user(buf, user_buf, count))
+		return -EFAULT;
+
+	if (buf[0] == '1')
+		queue_work(hisi_hba->wq, &hisi_hba->debugfs_work);
+	else
+		return -EFAULT;
+
+	return count;
+}
+
+static const struct file_operations hisi_sas_debugfs_trigger_dump_fops = {
+	.write = &hisi_sas_debugfs_trigger_dump_write,
+	.owner = THIS_MODULE,
+};
+
 void hisi_sas_debugfs_work_handler(struct work_struct *work)
 {
 	struct hisi_hba *hisi_hba =
@@ -3091,6 +3128,11 @@ void hisi_sas_debugfs_init(struct hisi_hba *hisi_hba)
 	if (!hisi_hba->debugfs_dir)
 		return;
 
+	debugfs_create_file("trigger_dump", 0600,
+			    hisi_hba->debugfs_dir,
+			    hisi_hba,
+			    &hisi_sas_debugfs_trigger_dump_fops);
+
 	/* Alloc buffer for global */
 	sz = hisi_hba->hw->debugfs_reg_global->count * 4;
 	hisi_hba->debugfs_global_reg =