ath9k_hw: add common channel select helpers for ar900[23]

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/ar9002_phy.c b/drivers/net/wireless/ath/ath9k/ar9002_phy.c
index 87541a8..1f8ac0a 100644
--- a/drivers/net/wireless/ath/ath9k/ar9002_phy.c
+++ b/drivers/net/wireless/ath/ath9k/ar9002_phy.c
@@ -83,7 +83,7 @@
 		bMode = 1;
 		fracMode = 1;
 		aModeRefSel = 0;
-		channelSel = (freq * 0x10000) / 15;
+		channelSel = CHANSEL_2G(freq);
 
 		if (AR_SREV_9287_11_OR_LATER(ah)) {
 			if (freq == 2484) {
@@ -126,7 +126,7 @@
 			 */
 			fracMode = 1;
 			refDivA = 1;
-			channelSel = (freq * 0x8000) / 15;
+			channelSel = CHANSEL_5G(freq);
 
 			/* RefDivA setting */
 			REG_RMW_FIELD(ah, AR_AN_SYNTH9,
diff --git a/drivers/net/wireless/ath/ath9k/phy.h b/drivers/net/wireless/ath/ath9k/phy.h
index b908152..7d397fd 100644
--- a/drivers/net/wireless/ath/ath9k/phy.h
+++ b/drivers/net/wireless/ath/ath9k/phy.h
@@ -17,6 +17,10 @@
 #ifndef PHY_H
 #define PHY_H
 
+#define CHANSEL_DIV		15
+#define CHANSEL_2G(_freq)	(((_freq) * 0x10000) / CHANSEL_DIV)
+#define CHANSEL_5G(_freq)	(((_freq) * 0x8000) / CHANSEL_DIV)
+
 #define AR_PHY_BASE     0x9800
 #define AR_PHY(_n)      (AR_PHY_BASE + ((_n)<<2))