rt2x00: Fix chipset revision validation

The validation of the chipset revision was broken
since for rt2500usb and rt73usb different registers
should be read. When rt2500usb was loaded for a rt73
device it would false think the chipset was correct
because the wrong register was read and validated.

This has been fixed by expanding the check to also
see if the first 4 bits of the revision is not-0
(When reading the wrong register offset the returned
value is usually 0 which can be interpreted as invalid)

Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rt2x00/rt2500pci.c b/drivers/net/wireless/rt2x00/rt2500pci.c
index ff2d632..702321c 100644
--- a/drivers/net/wireless/rt2x00/rt2500pci.c
+++ b/drivers/net/wireless/rt2x00/rt2500pci.c
@@ -620,7 +620,7 @@
 	 * up to version C the link tuning should halt after 20
 	 * seconds.
 	 */
-	if (rt2x00_get_rev(&rt2x00dev->chip) < RT2560_VERSION_D &&
+	if (rt2x00_rev(&rt2x00dev->chip) < RT2560_VERSION_D &&
 	    rt2x00dev->link.count > 20)
 		return;
 
@@ -630,7 +630,7 @@
 	 * Chipset versions C and lower should directly continue
 	 * to the dynamic CCA tuning.
 	 */
-	if (rt2x00_get_rev(&rt2x00dev->chip) < RT2560_VERSION_D)
+	if (rt2x00_rev(&rt2x00dev->chip) < RT2560_VERSION_D)
 		goto dynamic_cca_tune;
 
 	/*
diff --git a/drivers/net/wireless/rt2x00/rt2500usb.c b/drivers/net/wireless/rt2x00/rt2500usb.c
index 7cdc80a..277a020 100644
--- a/drivers/net/wireless/rt2x00/rt2500usb.c
+++ b/drivers/net/wireless/rt2x00/rt2500usb.c
@@ -753,7 +753,7 @@
 	rt2x00_set_field16(&reg, MAC_CSR1_HOST_READY, 1);
 	rt2500usb_register_write(rt2x00dev, MAC_CSR1, reg);
 
-	if (rt2x00_get_rev(&rt2x00dev->chip) >= RT2570_VERSION_C) {
+	if (rt2x00_rev(&rt2x00dev->chip) >= RT2570_VERSION_C) {
 		rt2500usb_register_read(rt2x00dev, PHY_CSR2, &reg);
 		reg &= ~0x0002;
 	} else {
@@ -1257,7 +1257,7 @@
 	rt2500usb_register_read(rt2x00dev, MAC_CSR0, &reg);
 	rt2x00_set_chip(rt2x00dev, RT2570, value, reg);
 
-	if (rt2x00_rev(&rt2x00dev->chip, 0xffff0)) {
+	if (!rt2x00_check_rev(&rt2x00dev->chip, 0)) {
 		ERROR(rt2x00dev, "Invalid RT chipset detected.\n");
 		return -ENODEV;
 	}
diff --git a/drivers/net/wireless/rt2x00/rt2x00.h b/drivers/net/wireless/rt2x00/rt2x00.h
index 9845e58..d1ad525 100644
--- a/drivers/net/wireless/rt2x00/rt2x00.h
+++ b/drivers/net/wireless/rt2x00/rt2x00.h
@@ -751,14 +751,16 @@
 	return (chipset->rf == chip);
 }
 
-static inline u16 rt2x00_get_rev(const struct rt2x00_chip *chipset)
+static inline u16 rt2x00_rev(const struct rt2x00_chip *chipset)
 {
 	return chipset->rev;
 }
 
-static inline u16 rt2x00_rev(const struct rt2x00_chip *chipset, const u32 mask)
+static inline u16 rt2x00_check_rev(const struct rt2x00_chip *chipset,
+				   const u32 rev)
 {
-	return chipset->rev & mask;
+	return (((chipset->rev & 0xffff0) == rev) &&
+		!!(chipset->rev & 0x0000f));
 }
 
 /*
diff --git a/drivers/net/wireless/rt2x00/rt73usb.c b/drivers/net/wireless/rt2x00/rt73usb.c
index 46c8c08..dc640bf 100644
--- a/drivers/net/wireless/rt2x00/rt73usb.c
+++ b/drivers/net/wireless/rt2x00/rt73usb.c
@@ -1486,7 +1486,7 @@
 	rt73usb_register_read(rt2x00dev, MAC_CSR0, &reg);
 	rt2x00_set_chip(rt2x00dev, RT2571, value, reg);
 
-	if (!rt2x00_rev(&rt2x00dev->chip, 0x25730)) {
+	if (!rt2x00_check_rev(&rt2x00dev->chip, 0x25730)) {
 		ERROR(rt2x00dev, "Invalid RT chipset detected.\n");
 		return -ENODEV;
 	}