bnx2x: Prevent probe as early as possible

It's possible that due to errors [either on PCI or on device itself]
registers reads would fail, returning all-Fs.

This adds a check as early as possible so that driver will not read junk
values and make incorrect probe decisions according to them; instead,
gracefully fail the probe.

Signed-off-by: Yuval Mintz <Yuval.Mintz@qlogic.com>
Signed-off-by: Ariel Elior <Ariel.Elior@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c

diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
index 8120d26..768dfb1 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c
@@ -11650,6 +11650,13 @@
 	u32 val = 0, val2 = 0;
 	int rc = 0;
 
+	/* Validate that chip access is feasible */
+	if (REG_RD(bp, MISC_REG_CHIP_NUM) == 0xffffffff) {
+		dev_err(&bp->pdev->dev,
+			"Chip read returns all Fs. Preventing probe from continuing\n");
+		return -EINVAL;
+	}
+
 	bnx2x_get_common_hwinfo(bp);
 
 	/*