ionic: fix fw_status read

The fw_status field is only 8 bits, so fix the read.  Also,
we only want to look at the one status bit, to allow for future
use of the other bits, and watch for a bad PCI read.

Fixes: 97ca4865 ("ionic: add heartbeat check")
Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/pensando/ionic/ionic_dev.c

@@ -103,7 +103,7 @@ int ionic_heartbeat_check(struct ionic *ionic)
 {
 	struct ionic_dev *idev = &ionic->idev;
 	unsigned long hb_time;
-	u32 fw_status;
+	u8 fw_status;
 	u32 hb;
 
 	/* wait a little more than one second before testing again */
@@ -111,9 +111,12 @@ int ionic_heartbeat_check(struct ionic *ionic)
 	if (time_before(hb_time, (idev->last_hb_time + ionic->watchdog_period)))
 		return 0;
 
-	/* firmware is useful only if fw_status is non-zero */
-	fw_status = ioread32(&idev->dev_info_regs->fw_status);
-	if (!fw_status)
+	/* firmware is useful only if the running bit is set and
+	 * fw_status != 0xff (bad PCI read)
+	 */
+	fw_status = ioread8(&idev->dev_info_regs->fw_status);
+	if (fw_status == 0xff ||
+	    !(fw_status & IONIC_FW_STS_F_RUNNING))
 		return -ENXIO;
 
 	/* early FW has no heartbeat, else FW will return non-zero */

drivers/net/ethernet/pensando/ionic/ionic_if.h

@@ -2445,6 +2445,7 @@ union ionic_dev_info_regs {
 		u8     version;
 		u8     asic_type;
 		u8     asic_rev;
+#define IONIC_FW_STS_F_RUNNING	0x1
 		u8     fw_status;
 		u32    fw_heartbeat;
 		char   fw_version[IONIC_DEVINFO_FWVERS_BUFLEN];