carl9170: use generic sign_extend32

This patch replaces the handcrafted
sign extension cruft with a generic
bitop function.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/carl9170/phy.c

@@ -1554,15 +1554,6 @@ static int carl9170_set_power_cal(struct ar9170 *ar, u32 freq,
 	return carl9170_regwrite_result();
 }
 
-/* TODO: replace this with sign_extend32(noise, 8) */
-static int carl9170_calc_noise_dbm(u32 raw_noise)
-{
-	if (raw_noise & 0x100)
-		return ~0x1ff | raw_noise;
-	else
-		return raw_noise;
-}
-
 int carl9170_get_noisefloor(struct ar9170 *ar)
 {
 	static const u32 phy_regs[] = {
@@ -1578,11 +1569,11 @@ int carl9170_get_noisefloor(struct ar9170 *ar)
 		return err;
 
 	for (i = 0; i < 2; i++) {
-		ar->noise[i] = carl9170_calc_noise_dbm(
-			(phy_res[i] >> 19) & 0x1ff);
+		ar->noise[i] = sign_extend32(GET_VAL(
+			AR9170_PHY_CCA_MIN_PWR, phy_res[i]), 8);
 
-		ar->noise[i + 2] = carl9170_calc_noise_dbm(
-			(phy_res[i + 2] >> 23) & 0x1ff);
+		ar->noise[i + 2] = sign_extend32(GET_VAL(
+			AR9170_PHY_EXT_CCA_MIN_PWR, phy_res[i + 2]), 8);
 	}
 
 	return 0;