ath9k_hw: clean up the noise floor calibration code to reduce code duplication

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/ar5008_phy.c b/drivers/net/wireless/ath/ath9k/ar5008_phy.c
index c675182..48c5a5f 100644
--- a/drivers/net/wireless/ath/ath9k/ar5008_phy.c
+++ b/drivers/net/wireless/ath/ath9k/ar5008_phy.c
@@ -1495,50 +1495,25 @@
 static void ar5008_hw_do_getnf(struct ath_hw *ah,
 			      int16_t nfarray[NUM_NF_READINGS])
 {
-	struct ath_common *common = ath9k_hw_common(ah);
 	int16_t nf;
 
 	nf = MS(REG_READ(ah, AR_PHY_CCA), AR_PHY_MINCCA_PWR);
-	if (nf & 0x100)
-		nf = 0 - ((nf ^ 0x1ff) + 1);
-	ath_print(common, ATH_DBG_CALIBRATE,
-		  "NF calibrated [ctl] [chain 0] is %d\n", nf);
-	nfarray[0] = nf;
+	nfarray[0] = sign_extend(nf, 9);
 
 	nf = MS(REG_READ(ah, AR_PHY_CH1_CCA), AR_PHY_CH1_MINCCA_PWR);
-	if (nf & 0x100)
-		nf = 0 - ((nf ^ 0x1ff) + 1);
-	ath_print(common, ATH_DBG_CALIBRATE,
-		  "NF calibrated [ctl] [chain 1] is %d\n", nf);
-	nfarray[1] = nf;
+	nfarray[1] = sign_extend(nf, 9);
 
 	nf = MS(REG_READ(ah, AR_PHY_CH2_CCA), AR_PHY_CH2_MINCCA_PWR);
-	if (nf & 0x100)
-		nf = 0 - ((nf ^ 0x1ff) + 1);
-	ath_print(common, ATH_DBG_CALIBRATE,
-		  "NF calibrated [ctl] [chain 2] is %d\n", nf);
-	nfarray[2] = nf;
+	nfarray[2] = sign_extend(nf, 9);
 
 	nf = MS(REG_READ(ah, AR_PHY_EXT_CCA), AR_PHY_EXT_MINCCA_PWR);
-	if (nf & 0x100)
-		nf = 0 - ((nf ^ 0x1ff) + 1);
-	ath_print(common, ATH_DBG_CALIBRATE,
-		  "NF calibrated [ext] [chain 0] is %d\n", nf);
-	nfarray[3] = nf;
+	nfarray[3] = sign_extend(nf, 9);
 
 	nf = MS(REG_READ(ah, AR_PHY_CH1_EXT_CCA), AR_PHY_CH1_EXT_MINCCA_PWR);
-	if (nf & 0x100)
-		nf = 0 - ((nf ^ 0x1ff) + 1);
-	ath_print(common, ATH_DBG_CALIBRATE,
-		  "NF calibrated [ext] [chain 1] is %d\n", nf);
-	nfarray[4] = nf;
+	nfarray[4] = sign_extend(nf, 9);
 
 	nf = MS(REG_READ(ah, AR_PHY_CH2_EXT_CCA), AR_PHY_CH2_EXT_MINCCA_PWR);
-	if (nf & 0x100)
-		nf = 0 - ((nf ^ 0x1ff) + 1);
-	ath_print(common, ATH_DBG_CALIBRATE,
-		  "NF calibrated [ext] [chain 2] is %d\n", nf);
-	nfarray[5] = nf;
+	nfarray[5] = sign_extend(nf, 9);
 }
 
 static void ar5008_hw_loadnf(struct ath_hw *ah, struct ath9k_channel *chan)