scsi: libsas: Define NCQ Priority sysfs attributes for SATA devices

libata sysfs attributes cannot be used for libsas-managed SATA devices
because the ata_port location is different for libsas.

Defined sysfs attributes (visible for SATA devices only):

- /sys/block/sda/device/ncq_prio_enable
- /sys/block/sda/device/ncq_prio_supported

The newly defined attributes will pass the correct ata_port to libata
helper functions.

Reviewed-by: John Garry <[e-mail]>
Reviewed-by: Damien Le Moal <[e-mail]>
Reviewed-by: Jason Yan <[e-mail]>
Signed-off-by: Igor Pylypiv <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Niklas Cassel <[e-mail]>
Signed-off-by: Martin K. Petersen <[e-mail]>

drivers/scsi/libsas/sas_ata.c

···
 			       force_phy_id, &tmf_task);
 }
 EXPORT_SYMBOL_GPL(sas_execute_ata_cmd);
+
+static ssize_t sas_ncq_prio_supported_show(struct device *device,
+					   struct device_attribute *attr,
+					   char *buf)
+{
+	struct scsi_device *sdev = to_scsi_device(device);
+	struct domain_device *ddev = sdev_to_domain_dev(sdev);
+	bool supported;
+	int rc;
+
+	rc = ata_ncq_prio_supported(ddev->sata_dev.ap, sdev, &supported);
+	if (rc)
+		return rc;
+
+	return sysfs_emit(buf, "%d\n", supported);
+}
+
+DEVICE_ATTR(ncq_prio_supported, S_IRUGO, sas_ncq_prio_supported_show, NULL);
+
+static ssize_t sas_ncq_prio_enable_show(struct device *device,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct scsi_device *sdev = to_scsi_device(device);
+	struct domain_device *ddev = sdev_to_domain_dev(sdev);
+	bool enabled;
+	int rc;
+
+	rc = ata_ncq_prio_enabled(ddev->sata_dev.ap, sdev, &enabled);
+	if (rc)
+		return rc;
+
+	return sysfs_emit(buf, "%d\n", enabled);
+}
+
+static ssize_t sas_ncq_prio_enable_store(struct device *device,
+					 struct device_attribute *attr,
+					 const char *buf, size_t len)
+{
+	struct scsi_device *sdev = to_scsi_device(device);
+	struct domain_device *ddev = sdev_to_domain_dev(sdev);
+	bool enable;
+	int rc;
+
+	rc = kstrtobool(buf, &enable);
+	if (rc)
+		return rc;
+
+	rc = ata_ncq_prio_enable(ddev->sata_dev.ap, sdev, enable);
+	if (rc)
+		return rc;
+
+	return len;
+}
+
+DEVICE_ATTR(ncq_prio_enable, S_IRUGO | S_IWUSR,
+	    sas_ncq_prio_enable_show, sas_ncq_prio_enable_store);
+
+static struct attribute *sas_ata_sdev_attrs[] = {
+	&dev_attr_ncq_prio_supported.attr,
+	&dev_attr_ncq_prio_enable.attr,
+	NULL
+};
+
+static umode_t sas_ata_attr_is_visible(struct kobject *kobj,
+				       struct attribute *attr, int i)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct scsi_device *sdev = to_scsi_device(dev);
+	struct domain_device *ddev = sdev_to_domain_dev(sdev);
+
+	if (!dev_is_sata(ddev))
+		return 0;
+
+	return attr->mode;
+}
+
+const struct attribute_group sas_ata_sdev_attr_group = {
+	.attrs = sas_ata_sdev_attrs,
+	.is_visible = sas_ata_attr_is_visible,
+};
+EXPORT_SYMBOL_GPL(sas_ata_sdev_attr_group);

include/scsi/sas_ata.h

···
 int sas_discover_sata(struct domain_device *dev);
 int sas_ata_add_dev(struct domain_device *parent, struct ex_phy *phy,
 		    struct domain_device *child, int phy_id);
+
+extern const struct attribute_group sas_ata_sdev_attr_group;
+
 #else
 
 static inline void sas_ata_disabled_notice(void)
···
 	sas_ata_disabled_notice();
 	return -ENODEV;
 }
+
+#define sas_ata_sdev_attr_group ((struct attribute_group) {})
+
 #endif
 
 #endif /* _SAS_ATA_H_ */