+/**
+ * _ctl_BRM_status_show - Backup Rail Monitor Status
+ * @cdev - pointer to embedded class device
+ * @buf - the buffer returned
+ *
+ * This is number of reply queues
+ *
+ * A sysfs 'read-only' shost attribute.
+ */
+static ssize_t
+_ctl_BRM_status_show(struct device *cdev, struct device_attribute *attr,
+ char *buf)
+{
+ struct Scsi_Host *shost = class_to_shost(cdev);
+ struct MPT3SAS_ADAPTER *ioc = shost_priv(shost);
+ Mpi2IOUnitPage3_t *io_unit_pg3 = NULL;
+ Mpi2ConfigReply_t mpi_reply;
+ u16 backup_rail_monitor_status = 0;
+ u16 ioc_status;
+ int sz;
+ ssize_t rc = 0;
+
+ if (!ioc->is_warpdrive) {
+ pr_err(MPT3SAS_FMT "%s: BRM attribute is only for"
+ " warpdrive\n", ioc->name, __func__);
+ goto out;
+ }
+ /* pci_access_mutex lock acquired by sysfs show path */
+ mutex_lock(&ioc->pci_access_mutex);
+ if (ioc->pci_error_recovery || ioc->remove_host) {
+ mutex_unlock(&ioc->pci_access_mutex);
+ return 0;
+ }
+
+ /* allocate upto GPIOVal 36 entries */
+ sz = offsetof(Mpi2IOUnitPage3_t, GPIOVal) + (sizeof(u16) * 36);
+ io_unit_pg3 = kzalloc(sz, GFP_KERNEL);
+ if (!io_unit_pg3) {
+ pr_err(MPT3SAS_FMT "%s: failed allocating memory "
+ "for iounit_pg3: (%d) bytes\n", ioc->name, __func__, sz);
+ goto out;
+ }
+
+ if (mpt3sas_config_get_iounit_pg3(ioc, &mpi_reply, io_unit_pg3, sz) !=
+ 0) {
+ pr_err(MPT3SAS_FMT
+ "%s: failed reading iounit_pg3\n", ioc->name,
+ __func__);
+ goto out;
+ }
+
+ ioc_status = le16_to_cpu(mpi_reply.IOCStatus) & MPI2_IOCSTATUS_MASK;
+ if (ioc_status != MPI2_IOCSTATUS_SUCCESS) {
+ pr_err(MPT3SAS_FMT "%s: iounit_pg3 failed with "
+ "ioc_status(0x%04x)\n", ioc->name, __func__, ioc_status);
+ goto out;
+ }
+
+ if (io_unit_pg3->GPIOCount < 25) {
+ pr_err(MPT3SAS_FMT "%s: iounit_pg3->GPIOCount less than "
+ "25 entries, detected (%d) entries\n", ioc->name, __func__,
+ io_unit_pg3->GPIOCount);
+ goto out;
+ }
+
+ /* BRM status is in bit zero of GPIOVal[24] */
+ backup_rail_monitor_status = le16_to_cpu(io_unit_pg3->GPIOVal[24]);
+ rc = snprintf(buf, PAGE_SIZE, "%d\n", (backup_rail_monitor_status & 1));
+
+ out:
+ kfree(io_unit_pg3);
+ mutex_unlock(&ioc->pci_access_mutex);
+ return rc;
+}
+static DEVICE_ATTR(BRM_status, S_IRUGO, _ctl_BRM_status_show, NULL);
+