cxgb4: Wait for device to get ready before reading any register

Call t4_wait_dev_ready() before attempting to read the PL_WHOAMI register
(to determine which function we have been attached to). This prevents us from
failing on that read if it comes right after a RESET.
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/cxgb4.h

@@ -968,7 +968,7 @@ void t4_intr_enable(struct adapter *adapter);
 void t4_intr_disable(struct adapter *adapter);
 int t4_slow_intr_handler(struct adapter *adapter);
 
-int t4_wait_dev_ready(struct adapter *adap);
+int t4_wait_dev_ready(void __iomem *regs);
 int t4_link_start(struct adapter *adap, unsigned int mbox, unsigned int port,
 		  struct link_config *lc);
 int t4_restart_aneg(struct adapter *adap, unsigned int mbox, unsigned int port);

drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c

@@ -6137,7 +6137,7 @@ static pci_ers_result_t eeh_slot_reset(struct pci_dev *pdev)
 	pci_save_state(pdev);
 	pci_cleanup_aer_uncorrect_error_status(pdev);
 
-	if (t4_wait_dev_ready(adap) < 0)
+	if (t4_wait_dev_ready(adap->regs) < 0)
 		return PCI_ERS_RESULT_DISCONNECT;
 	if (t4_fw_hello(adap, adap->fn, adap->fn, MASTER_MUST, NULL) < 0)
 		return PCI_ERS_RESULT_DISCONNECT;
@@ -6530,6 +6530,10 @@ static int init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 		goto out_disable_device;
 	}
 
+	err = t4_wait_dev_ready(regs);
+	if (err < 0)
+		goto out_unmap_bar0;
+
 	/* We control everything through one PF */
 	func = SOURCEPF_GET(readl(regs + PL_WHOAMI));
 	if (func != ent->driver_data) {

drivers/net/ethernet/chelsio/cxgb4/t4_hw.c

@@ -3845,12 +3845,19 @@ static void init_link_config(struct link_config *lc, unsigned int caps)
 	}
 }
 
-int t4_wait_dev_ready(struct adapter *adap)
+#define CIM_PF_NOACCESS 0xeeeeeeee
+
+int t4_wait_dev_ready(void __iomem *regs)
 {
-	if (t4_read_reg(adap, PL_WHOAMI) != 0xffffffff)
+	u32 whoami;
+
+	whoami = readl(regs + PL_WHOAMI);
+	if (whoami != 0xffffffff && whoami != CIM_PF_NOACCESS)
 		return 0;
+
 	msleep(500);
-	return t4_read_reg(adap, PL_WHOAMI) != 0xffffffff ? 0 : -EIO;
+	whoami = readl(regs + PL_WHOAMI);
+	return (whoami != 0xffffffff && whoami != CIM_PF_NOACCESS ? 0 : -EIO);
 }
 
 struct flash_desc {
@@ -3919,10 +3926,6 @@ int t4_prep_adapter(struct adapter *adapter)
 	uint16_t device_id;
 	u32 pl_rev;
 
-	ret = t4_wait_dev_ready(adapter);
-	if (ret < 0)
-		return ret;
-
 	get_pci_mode(adapter, &adapter->params.pci);
 	pl_rev = G_REV(t4_read_reg(adapter, PL_REV));