scsi: hisi_sas: Try wait commands before before controller reset

We may reset the controller in many scenarios, such as SCSI EH and HW
errors. There should be no IO which returns from target when SCSI EH is
active. But for other scenarios, there may be.  It is not necessary to make
such IOs fail.

This patch adds an function of trying to wait for any commands, or IO, to
complete before host reset. If no more CQ returned from host controller in
100ms, we assume no more IO can return, and then stop waiting. We wait 5s
at most.

The HW has a register CQE_SEND_CNT to indicate the total number of CQs that
has been reported to driver. We can use this register and it is reliable to
resd this register in such scenarios that require host reset.

Signed-off-by: Xiaofei Tan <tanxiaofei@huawei.com>
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

4 files changed, 43 insertions, 0 deletions

diff --git a/drivers/scsi/hisi_sas/hisi_sas.h b/drivers/scsi/hisi_sas/hisi_sas.h
index 37c9a6246dc8..8ce6abb48867 100644
--- a/drivers/scsi/hisi_sas/hisi_sas.h
+++ b/drivers/scsi/hisi_sas/hisi_sas.h
@@ -246,6 +246,8 @@ struct hisi_sas_hw {
 	u32 (*get_phys_state)(struct hisi_hba *hisi_hba);
 	int (*write_gpio)(struct hisi_hba *hisi_hba, u8 reg_type,
 				u8 reg_index, u8 reg_count, u8 *write_data);
+	void (*wait_cmds_complete_timeout)(struct hisi_hba *hisi_hba,
+					   int delay_ms, int timeout_ms);
 	int max_command_entries;
 	int complete_hdr_size;
 	struct scsi_host_template *sht;
diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c b/drivers/scsi/hisi_sas/hisi_sas_main.c
index dc67bd7c7ab0..5bc522c35690 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_main.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_main.c
@@ -1293,6 +1293,8 @@ static int hisi_sas_controller_reset(struct hisi_hba *hisi_hba)
 	old_state = hisi_hba->hw->get_phys_state(hisi_hba);
 
 	scsi_block_requests(shost);
+	hisi_hba->hw->wait_cmds_complete_timeout(hisi_hba, 100, 5000);
+
 	if (timer_pending(&hisi_hba->timer))
 		del_timer_sync(&hisi_hba->timer);
 
diff --git a/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
index 8def327c4f46..18dbaffc9988 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_v2_hw.c
@@ -144,6 +144,7 @@
 #define SAS_ECC_INTR_NCQ_MEM3_ECC_1B_OFF	19
 #define SAS_ECC_INTR_MSK		0x1ec
 #define HGC_ERR_STAT_EN			0x238
+#define CQE_SEND_CNT			0x248
 #define DLVRY_Q_0_BASE_ADDR_LO		0x260
 #define DLVRY_Q_0_BASE_ADDR_HI		0x264
 #define DLVRY_Q_0_DEPTH			0x268
@@ -3501,6 +3502,23 @@ static int write_gpio_v2_hw(struct hisi_hba *hisi_hba, u8 reg_type,
 	return 0;
 }
 
+static void wait_cmds_complete_timeout_v2_hw(struct hisi_hba *hisi_hba,
+					     int delay_ms, int timeout_ms)
+{
+	struct device *dev = hisi_hba->dev;
+	int entries, entries_old = 0, time;
+
+	for (time = 0; time < timeout_ms; time += delay_ms) {
+		entries = hisi_sas_read32(hisi_hba, CQE_SEND_CNT);
+		if (entries == entries_old)
+			break;
+
+		entries_old = entries;
+		msleep(delay_ms);
+	}
+
+	dev_dbg(dev, "wait commands complete %dms\n", time);
+}
 
 static struct scsi_host_template sht_v2_hw = {
 	.name			= DRV_NAME,
@@ -3552,6 +3570,7 @@ static const struct hisi_sas_hw hisi_sas_v2_hw = {
 	.soft_reset = soft_reset_v2_hw,
 	.get_phys_state = get_phys_state_v2_hw,
 	.write_gpio = write_gpio_v2_hw,
+	.wait_cmds_complete_timeout = wait_cmds_complete_timeout_v2_hw,
 	.sht = &sht_v2_hw,
 };
 
diff --git a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
index 13d21349d1ba..dd5f542bbc45 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_v3_hw.c
@@ -92,6 +92,7 @@
 #define SAS_ECC_INTR			0x1e8
 #define SAS_ECC_INTR_MSK		0x1ec
 #define HGC_ERR_STAT_EN			0x238
+#define CQE_SEND_CNT			0x248
 #define DLVRY_Q_0_BASE_ADDR_LO		0x260
 #define DLVRY_Q_0_BASE_ADDR_HI		0x264
 #define DLVRY_Q_0_DEPTH			0x268
@@ -2015,6 +2016,24 @@ static int write_gpio_v3_hw(struct hisi_hba *hisi_hba, u8 reg_type,
 	return 0;
 }
 
+static void wait_cmds_complete_timeout_v3_hw(struct hisi_hba *hisi_hba,
+					     int delay_ms, int timeout_ms)
+{
+	struct device *dev = hisi_hba->dev;
+	int entries, entries_old = 0, time;
+
+	for (time = 0; time < timeout_ms; time += delay_ms) {
+		entries = hisi_sas_read32(hisi_hba, CQE_SEND_CNT);
+		if (entries == entries_old)
+			break;
+
+		entries_old = entries;
+		msleep(delay_ms);
+	}
+
+	dev_dbg(dev, "wait commands complete %dms\n", time);
+}
+
 static struct scsi_host_template sht_v3_hw = {
 	.name			= DRV_NAME,
 	.module			= THIS_MODULE,
@@ -2063,6 +2082,7 @@ static const struct hisi_sas_hw hisi_sas_v3_hw = {
 	.get_phys_state = get_phys_state_v3_hw,
 	.get_events = phy_get_events_v3_hw,
 	.write_gpio = write_gpio_v3_hw,
+	.wait_cmds_complete_timeout = wait_cmds_complete_timeout_v3_hw,
 };
 
 static struct Scsi_Host *