[PATCH 08/13] scsi: hisi_sas: Try wait commands before before controller reset

[John Garry <john.garry@huawei.com>]

From: Xiaofei Tan <tanxiaofei@huawei.com>

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 failure.

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>
---
 drivers/scsi/hisi_sas/hisi_sas.h       |  2 ++
 drivers/scsi/hisi_sas/hisi_sas_main.c  |  2 ++
 drivers/scsi/hisi_sas/hisi_sas_v2_hw.c | 19 +++++++++++++++++++
 drivers/scsi/hisi_sas/hisi_sas_v3_hw.c | 20 ++++++++++++++++++++
 4 files changed, 43 insertions(+)

diff --git a/drivers/scsi/hisi_sas/hisi_sas.h b/drivers/scsi/hisi_sas/hisi_sas.h
index 37c9a62..8ce6abb 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 0dfefdf..a6fcfb3 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 8def327..18dbaff 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 int write_gpio_v2_hw(struct hisi_hba *hisi_hba, u8 reg_type,
 	.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 13d2134..dd5f542 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 int write_gpio_v3_hw(struct hisi_hba *hisi_hba, u8 reg_type,
 	.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 *
-- 
1.9.1