ath5k: Disable interrupts in ath5k_hw_get_tsf64

The code in ath5k_hw_get_tsf64() is time critical and will return wrong results
if we get interrupted, so disable local interrupts.
Signed-off-by: Bruno Randolf <br1@einfach.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath5k/pcu.c

@@ -495,6 +495,10 @@ u64 ath5k_hw_get_tsf64(struct ath5k_hw *ah)
 {
 	u32 tsf_lower, tsf_upper1, tsf_upper2;
 	int i;
+	unsigned long flags;
+
+	/* This code is time critical - we don't want to be interrupted here */
+	local_irq_save(flags);
 
 	/*
 	 * While reading TSF upper and then lower part, the clock is still
@@ -517,6 +521,8 @@ u64 ath5k_hw_get_tsf64(struct ath5k_hw *ah)
 		tsf_upper1 = tsf_upper2;
 	}
 
+	local_irq_restore(flags);
+
 	WARN_ON( i == ATH5K_MAX_TSF_READ );
 
 	return (((u64)tsf_upper1 << 32) | tsf_lower);