scsi: hisi_sas: Record the phy down event in debugfs

The number of phy down reflects the quality of the link between SAS
controller and disk. In order to allow the user to confirm the link quality
of the system, we record the number of phy down for each phy.

The user can check the current phy down count by reading the debugfs file
corresponding to the specific phy, or clear the phy down count by writing 0
to the debugfs file.

Link: https://lore.kernel.org/r/1571926105-74636-19-git-send-email-john.garry@huawei.com
Signed-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

@@ -169,6 +169,7 @@ struct hisi_sas_phy {
 	enum sas_linkrate	minimum_linkrate;
 	enum sas_linkrate	maximum_linkrate;
 	int enable;
+	atomic_t down_cnt;
 };
 
 struct hisi_sas_port {

drivers/scsi/hisi_sas/hisi_sas_main.c

@@ -3705,6 +3705,52 @@ static const struct file_operations hisi_sas_debugfs_bist_enable_ops = {
 	.owner = THIS_MODULE,
 };
 
+static ssize_t hisi_sas_debugfs_phy_down_cnt_write(struct file *filp,
+						   const char __user *buf,
+						   size_t count, loff_t *ppos)
+{
+	struct seq_file *s = filp->private_data;
+	struct hisi_sas_phy *phy = s->private;
+	unsigned int set_val;
+	int res;
+
+	res = kstrtouint_from_user(buf, count, 0, &set_val);
+	if (res)
+		return res;
+
+	if (set_val > 0)
+		return -EINVAL;
+
+	atomic_set(&phy->down_cnt, 0);
+
+	return count;
+}
+
+static int hisi_sas_debugfs_phy_down_cnt_show(struct seq_file *s, void *p)
+{
+	struct hisi_sas_phy *phy = s->private;
+
+	seq_printf(s, "%d\n", atomic_read(&phy->down_cnt));
+
+	return 0;
+}
+
+static int hisi_sas_debugfs_phy_down_cnt_open(struct inode *inode,
+					      struct file *filp)
+{
+	return single_open(filp, hisi_sas_debugfs_phy_down_cnt_show,
+			   inode->i_private);
+}
+
+static const struct file_operations hisi_sas_debugfs_phy_down_cnt_ops = {
+	.open = hisi_sas_debugfs_phy_down_cnt_open,
+	.read = seq_read,
+	.write = hisi_sas_debugfs_phy_down_cnt_write,
+	.llseek = seq_lseek,
+	.release = single_release,
+	.owner = THIS_MODULE,
+};
+
 void hisi_sas_debugfs_work_handler(struct work_struct *work)
 {
 	struct hisi_hba *hisi_hba =
@@ -3839,6 +3885,21 @@ fail:
 	return -ENOMEM;
 }
 
+static void hisi_sas_debugfs_phy_down_cnt_init(struct hisi_hba *hisi_hba)
+{
+	struct dentry *dir = debugfs_create_dir("phy_down_cnt",
+						hisi_hba->debugfs_dir);
+	char name[16];
+	int phy_no;
+
+	for (phy_no = 0; phy_no < hisi_hba->n_phy; phy_no++) {
+		snprintf(name, 16, "%d", phy_no);
+		debugfs_create_file(name, 0600, dir,
+				    &hisi_hba->phy[phy_no],
+				    &hisi_sas_debugfs_phy_down_cnt_ops);
+	}
+}
+
 static void hisi_sas_debugfs_bist_init(struct hisi_hba *hisi_hba)
 {
 	hisi_hba->debugfs_bist_dentry =
@@ -3885,6 +3946,8 @@ void hisi_sas_debugfs_init(struct hisi_hba *hisi_hba)
 	hisi_hba->debugfs_dump_dentry =
 			debugfs_create_dir("dump", hisi_hba->debugfs_dir);
 
+	hisi_sas_debugfs_phy_down_cnt_init(hisi_hba);
+
 	for (i = 0; i < hisi_sas_debugfs_dump_count; i++) {
 		if (hisi_sas_debugfs_alloc(hisi_hba, i)) {
 			debugfs_remove_recursive(hisi_hba->debugfs_dir);

drivers/scsi/hisi_sas/hisi_sas_v3_hw.c

@@ -1549,6 +1549,8 @@ static irqreturn_t phy_down_v3_hw(int phy_no, struct hisi_hba *hisi_hba)
 	u32 phy_state, sl_ctrl, txid_auto;
 	struct device *dev = hisi_hba->dev;
 
+	atomic_inc(&phy->down_cnt);
+
 	del_timer(&phy->timer);
 	hisi_sas_phy_write32(hisi_hba, phy_no, PHYCTRL_NOT_RDY_MSK, 1);