scsi: smartpqi: Add host level stream detection enable

Allow R5/R6 stream detection to be disabled/enabled using sysfs entry
enable_stream_detection.

Example usage:

lsscsi
[2:2:0:0]    storage Adaptec  3258P-32i /e     0010
 ^
 |
 +---- NOTE: here host is host2

find /sys -name \*enable_stream\*
/sys/devices/pci0000:36/0000:36:00.0/0000:37:00.0/0000:38:00.0/0000:39:00.0/host2/scsi_host/host2/enable_stream_detection
/sys/devices/pci0000:5b/0000:5b:00.0/0000:5c:00.0/host3/scsi_host/host3/enable_stream_detection

Current stream detection:
cat /sys/devices/pci0000:36/0000:36:00.0/0000:37:00.0/0000:38:00.0/0000:39:00.0/host2/scsi_host/host2/enable_stream_detection
1

Turn off stream detection:
echo 0 > /sys/devices/pci0000:36/0000:36:00.0/0000:37:00.0/0000:38:00.0/0000:39:00.0/host2/scsi_host/host2/enable_stream_detection

Turn on stream detection:
echo 1 > /sys/devices/pci0000:36/0000:36:00.0/0000:37:00.0/0000:38:00.0/0000:39:00.0/host2/scsi_host/host2/enable_stream_detection

Link: https://lore.kernel.org/r/161549376281.25025.1132304698441513738.stgit@brunhildaReviewed-by: Scott Benesh <scott.benesh@microchip.com>
Reviewed-by: Mike McGowen <mike.mcgowen@microchip.com>
Reviewed-by: Scott Teel <scott.teel@microchip.com>
Reviewed-by: Kevin Barnett <kevin.barnett@microchip.com>
Reviewed-by: Martin Wilck <mwilck@suse.com>
Signed-off-by: Don Brace <don.brace@microchip.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/smartpqi/smartpqi_init.c

@@ -6696,6 +6696,34 @@ static ssize_t pqi_lockup_action_store(struct device *dev,
 	return -EINVAL;
 }
 
+static ssize_t pqi_host_enable_stream_detection_show(struct device *dev,
+	struct device_attribute *attr, char *buffer)
+{
+	struct Scsi_Host *shost = class_to_shost(dev);
+	struct pqi_ctrl_info *ctrl_info = shost_to_hba(shost);
+
+	return scnprintf(buffer, 10, "%x\n",
+			ctrl_info->enable_stream_detection);
+}
+
+static ssize_t pqi_host_enable_stream_detection_store(struct device *dev,
+	struct device_attribute *attr, const char *buffer, size_t count)
+{
+	struct Scsi_Host *shost = class_to_shost(dev);
+	struct pqi_ctrl_info *ctrl_info = shost_to_hba(shost);
+	u8 set_stream_detection = 0;
+
+	if (kstrtou8(buffer, 0, &set_stream_detection))
+		return -EINVAL;
+
+	if (set_stream_detection > 0)
+		set_stream_detection = 1;
+
+	ctrl_info->enable_stream_detection = set_stream_detection;
+
+	return count;
+}
+
 static ssize_t pqi_host_enable_r5_writes_show(struct device *dev,
 	struct device_attribute *attr, char *buffer)
 {
@@ -6758,6 +6786,9 @@ static DEVICE_ATTR(vendor, 0444, pqi_vendor_show, NULL);
 static DEVICE_ATTR(rescan, 0200, NULL, pqi_host_rescan_store);
 static DEVICE_ATTR(lockup_action, 0644, pqi_lockup_action_show,
 	pqi_lockup_action_store);
+static DEVICE_ATTR(enable_stream_detection, 0644,
+	pqi_host_enable_stream_detection_show,
+	pqi_host_enable_stream_detection_store);
 static DEVICE_ATTR(enable_r5_writes, 0644,
 	pqi_host_enable_r5_writes_show, pqi_host_enable_r5_writes_store);
 static DEVICE_ATTR(enable_r6_writes, 0644,
@@ -6771,6 +6802,7 @@ static struct device_attribute *pqi_shost_attrs[] = {
 	&dev_attr_vendor,
 	&dev_attr_rescan,
 	&dev_attr_lockup_action,
+	&dev_attr_enable_stream_detection,
 	&dev_attr_enable_r5_writes,
 	&dev_attr_enable_r6_writes,
 	NULL