mpt3sas: sysfs attribute to report Backup Rail Monitor Status

A new sysfs shost attribute called "BMR_status" is implemented to report
Backup Rail Monitor status.

This attribute is located in:

        /sys/class/scsi_host/host#/BMR_status

When reading this adapter attribute, the driver will output the state of
GPIO[24]. It returns "0" if BMR is healthy and "1" for failure.

If it returns an empty string then it means that there was an error
while obtaining the BMR status. Check dmesg for what error has occurred.

This sysfs shost attribute is mainly for WarpDrive controllers.

This commit is a port of 6c265660c262 ("mpt2sas: Provide sysfs attribute
to report Backup Rail Monitor Status").

Signed-off-by: Sreekanth Reddy <Sreekanth.Reddy@avagotech.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 74 insertions, 0 deletions

diff --git a/drivers/scsi/mpt3sas/mpt3sas_ctl.c b/drivers/scsi/mpt3sas/mpt3sas_ctl.c
index 3f22754adb4f..1c62db8d80c7 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_ctl.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_ctl.c
@@ -2720,6 +2720,77 @@ _ctl_ioc_reply_queue_count_show(struct device *cdev,
 static DEVICE_ATTR(reply_queue_count, S_IRUGO, _ctl_ioc_reply_queue_count_show,
 	NULL);
 
+#ifdef SCSI_MPT2SAS
+/**
+ * _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;
+	}
+
+	/* 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);
+	return rc;
+}
+static DEVICE_ATTR(BRM_status, S_IRUGO, _ctl_BRM_status_show, NULL);
+#endif
+
 struct DIAG_BUFFER_START {
 	__le32	Size;
 	__le32	DiagVersion;
@@ -3172,6 +3243,9 @@ struct device_attribute *mpt3sas_host_attrs[] = {
 	&dev_attr_diag_trigger_event,
 	&dev_attr_diag_trigger_scsi,
 	&dev_attr_diag_trigger_mpi,
+#ifdef SCSI_MPT2SAS
+	&dev_attr_BRM_status,
+#endif
 	NULL,
 };