net/smsc911x: Always wait for the chip to be ready

Wait for the chip to be ready before any access to it. On the
Snowball platform we need to enable an external regulator before
the chip comes online, and then it happens that the device is
not yet ready at probe time, so let's wait for it.
Signed-off-by: Robert Marklund <robert.marklund@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/smsc/smsc911x.c

@@ -1937,6 +1937,7 @@ static int __devinit smsc911x_init(struct net_device *dev)
 {
 	struct smsc911x_data *pdata = netdev_priv(dev);
 	unsigned int byte_test;
+	unsigned int to = 100;
 
 	SMSC_TRACE(pdata, probe, "Driver Parameters:");
 	SMSC_TRACE(pdata, probe, "LAN base: 0x%08lX",
@@ -1952,6 +1953,17 @@ static int __devinit smsc911x_init(struct net_device *dev)
 		return -ENODEV;
 	}
 
+	/*
+	 * poll the READY bit in PMT_CTRL. Any other access to the device is
+	 * forbidden while this bit isn't set. Try for 100ms
+	 */
+	while (!(smsc911x_reg_read(pdata, PMT_CTRL) & PMT_CTRL_READY_) && --to)
+		udelay(1000);
+	if (to == 0) {
+		pr_err("Device not READY in 100ms aborting\n");
+		return -ENODEV;
+	}
+
 	/* Check byte ordering */
 	byte_test = smsc911x_reg_read(pdata, BYTE_TEST);
 	SMSC_TRACE(pdata, probe, "BYTE_TEST: 0x%08X", byte_test);