openwrt/package/madwifi/patches/454-cca.patch

--- a/ath/if_ath.c
+++ b/ath/if_ath.c
@@ -383,6 +383,8 @@ static void ath_poll_disable(struct net_
 static void ath_poll_enable(struct net_device *dev);
 static void ath_fetch_idle_time(struct ath_softc *sc);
 static void ath_set_timing(struct ath_softc *sc);
+static void ath_update_cca_thresh(struct ath_softc *sc);
+static int ath_hw_read_nf(struct ath_softc *sc);
 
 /* calibrate every 30 secs in steady state but check every second at first. */
 static int ath_calinterval = ATH_SHORT_CALINTERVAL;
@@ -2623,6 +2625,10 @@ ath_init(struct net_device *dev)
 		goto done;
 	}
 
+	ath_hal_process_noisefloor(ah);
+	ic->ic_channoise = ath_hal_get_channel_noise(ah, &(sc->sc_curchan));
+	ath_update_cca_thresh(sc);
+
 	if (sc->sc_softled)
 		ath_hal_gpioCfgOutput(ah, sc->sc_ledpin);
 
@@ -3024,6 +3030,10 @@ ath_reset(struct net_device *dev)
 		EPRINTF(sc, "Unable to reset hardware: '%s' (HAL status %u)\n",
 			ath_get_hal_status_desc(status), status);
 
+	ath_hal_process_noisefloor(ah);
+	ic->ic_channoise = ath_hal_get_channel_noise(ah, &(sc->sc_curchan));
+	ath_update_cca_thresh(sc);
+
 	ath_setintmit(sc);
 	ath_update_txpow(sc);		/* update tx power state */
 	ath_radar_update(sc);
@@ -9374,9 +9384,11 @@ ath_calibrate(unsigned long arg)
 			sc->sc_curchan.channel);
 		sc->sc_stats.ast_per_calfail++;
 	}
-	ic->ic_channoise = ath_hal_get_channel_noise(ah, &(sc->sc_curchan));
 
 	ath_hal_process_noisefloor(ah);
+	ic->ic_channoise = ath_hal_get_channel_noise(ah, &(sc->sc_curchan));
+	ath_update_cca_thresh(sc);
+
 	if (isIQdone == AH_TRUE) {
 		/* Unless user has overridden calibration interval,
 		 * upgrade to less frequent calibration */
@@ -9711,8 +9723,6 @@ ath_newstate(struct ieee80211vap *vap, e
 			break;
 		}
 
-		ath_hal_process_noisefloor(ah);
-		ic->ic_channoise = ath_hal_get_channel_noise(ah, &(sc->sc_curchan));
 		/*
 		 * Reset rssi stats; maybe not the best place...
 		 */
@@ -10968,6 +10978,7 @@ enum {
 	ATH_INTMIT,
 	ATH_NOISE_IMMUNITY,
 	ATH_OFDM_WEAK_DET,
+	ATH_CCA_THRESH,
 	ATH_CHANBW,
 	ATH_OUTDOOR,
 	ATH_DISTANCE,
@@ -11110,6 +11121,66 @@ ath_sysctl_get_intmit(struct ath_softc *
 	return 0;
 }
 
+#define AR_PHY_CCA              0x9864
+#define AR_PHY_MINCCA_PWR       0x0FF80000
+#define AR_PHY_MINCCA_PWR_S     19
+#define AR_PHY_CCA_THRESH62     0x0007F000
+#define AR_PHY_CCA_THRESH62_S   12
+
+static int
+ath_nf_from_cca(u32 phy_cca)
+{
+	int nf = (phy_cca >> 19) & 0x1ff;
+	nf = -((nf ^ 0x1ff) + 1);
+	return nf;
+}
+
+static int
+ath_hw_read_nf(struct ath_softc *sc)
+{
+	return ath_nf_from_cca(OS_REG_READ(sc->sc_ah, AR_PHY_CCA));
+}
+
+static void
+ath_update_cca_thresh(struct ath_softc *sc)
+{
+	struct ath_hal *ah = sc->sc_ah;
+	int newthr = 0;
+	u32 phy_cca;
+	int nf;
+
+	phy_cca = OS_REG_READ(ah, AR_PHY_CCA);
+	if (sc->sc_cca_thresh < 0) {
+		newthr = sc->sc_cca_thresh - ath_nf_from_cca(phy_cca);
+
+		/* 0xf is a typical eeprom value for thresh62,
+		 * use it as minimum for signal based thresholds
+		 * to prevent complete connection drops */
+		if (newthr < 0xf)
+			newthr = 0xf;
+	} else {
+		newthr = sc->sc_cca_thresh;
+	}
+
+	if ((newthr < 4) || (newthr >= 127))
+		return;
+
+	phy_cca &= ~AR_PHY_CCA_THRESH62;
+	phy_cca |= newthr << AR_PHY_CCA_THRESH62_S;
+	OS_REG_WRITE(ah, AR_PHY_CCA, phy_cca);
+}
+
+static int
+ath_get_cca_thresh(struct ath_softc *sc)
+{
+	struct ath_hal *ah = sc->sc_ah;
+	u32 phy_cca;
+
+	phy_cca = OS_REG_READ(ah, AR_PHY_CCA);
+	return ath_nf_from_cca(phy_cca) +
+		((phy_cca & AR_PHY_CCA_THRESH62) >> AR_PHY_CCA_THRESH62_S);
+}
+
 static int
 ATH_SYSCTL_DECL(ath_sysctl_hwinfo, ctl, write, filp, buffer, lenp, ppos)
 {
@@ -11356,6 +11427,10 @@ ATH_SYSCTL_DECL(ath_sysctl_halparam, ctl
 			case ATH_OFDM_WEAK_DET:
 				ret = ath_sysctl_set_intmit(sc, (long)ctl->extra2, val);
 				break;
+			case ATH_CCA_THRESH:
+				sc->sc_cca_thresh = val;
+				ath_update_cca_thresh(sc);
+				break;
 			default:
 				ret = -EINVAL;
 				break;
@@ -11436,6 +11511,9 @@ ATH_SYSCTL_DECL(ath_sysctl_halparam, ctl
 		case ATH_OFDM_WEAK_DET:
 			ret = ath_sysctl_get_intmit(sc, (long)ctl->extra2, &val);
 			break;
+		case ATH_CCA_THRESH:
+			val = ath_get_cca_thresh(sc);
+			break;
 		default:
 			ret = -EINVAL;
 			break;
@@ -11667,6 +11745,12 @@ static const ctl_table ath_sysctl_templa
 	  .proc_handler = ath_sysctl_halparam,
 	  .extra2	= (void *)ATH_OFDM_WEAK_DET,
 	},
+	{ .ctl_name	= CTL_AUTO,
+	  .procname     = "cca_thresh",
+	  .mode         = 0644,
+	  .proc_handler = ath_sysctl_halparam,
+	  .extra2	= (void *)ATH_CCA_THRESH,
+	},
 	{ 0 }
 };
 
--- a/ath/if_athvar.h
+++ b/ath/if_athvar.h
@@ -844,6 +844,7 @@ struct ath_softc {
 	int sc_cal_interval;			/* current calibration interval */
 	struct timer_list sc_cal_ch;		/* calibration timer */
 	HAL_NODE_STATS sc_halstats;		/* station-mode rssi stats */
+	int sc_cca_thresh;				/* configured CCA threshold */
 
 	struct ctl_table_header *sc_sysctl_header;
 	struct ctl_table *sc_sysctls;
--- a/ath/ath_wprobe.c
+++ b/ath/ath_wprobe.c
@@ -133,8 +133,7 @@ ath_wprobe_sync(struct wprobe_iface *dev
 	rx = READ_CLR(ah, AR5K_RXFC);
 	tx = READ_CLR(ah, AR5K_TXFC);
 	OS_REG_WRITE(ah, AR5K_MIBC, 0);
-	noise = ath_hal_get_channel_noise(sc->sc_ah, &(sc->sc_curchan));
-	ic->ic_channoise = noise;
+	noise = ath_hw_read_nf(sc);
 
 	WPROBE_FILL_BEGIN(val, ath_wprobe_globals);
 	if (cc & 0xf0000000) {