ath5k: disable 5 GHz support for the dualband PHY chip on dual-radio AR5312

There are two variants of AR5312 dual-band devices, one single-radio
and the other one dual-radio. On the dual-radio board, the first MAC
only supports 5 GHz, even though it has a dual-band PHY. The 2.4 GHz
part of this phy is used in pass-through mode, connecting the second
MAC with the second PHY.
Disable 2.4 GHz for the first MAC on an AR5312, but only if the board
configuration indicates a dual-radio device.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

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

@@ -160,6 +160,16 @@ static int ath_ahb_probe(struct platform_device *pdev)
 		else
 			reg |= AR5K_AR5312_ENABLE_WLAN1;
 		__raw_writel(reg, (void __iomem *) AR5K_AR5312_ENABLE);
+
+		/*
+		 * On a dual-band AR5312, the multiband radio is only
+		 * used as pass-through. Disable 2 GHz support in the
+		 * driver for it
+		 */
+		if (to_platform_device(sc->dev)->id == 0 &&
+		    (bcfg->config->flags & (BD_WLAN0|BD_WLAN1)) ==
+		     (BD_WLAN1|BD_WLAN0))
+			__set_bit(ATH_STAT_2G_DISABLED, sc->status);
 	}
 
 	ret = ath5k_init_softc(sc, &ath_ahb_bus_ops);

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

@@ -313,6 +313,11 @@ int ath5k_hw_init(struct ath5k_softc *sc)
 		goto err;
 	}
 
+	if (test_bit(ATH_STAT_2G_DISABLED, sc->status)) {
+		__clear_bit(AR5K_MODE_11B, ah->ah_capabilities.cap_mode);
+		__clear_bit(AR5K_MODE_11G, ah->ah_capabilities.cap_mode);
+	}
+
 	/* Crypto settings */
 	common->keymax = (sc->ah->ah_version == AR5K_AR5210 ?
 			  AR5K_KEYTABLE_SIZE_5210 : AR5K_KEYTABLE_SIZE_5211);

drivers/net/wireless/ath/ath5k/base.h

@@ -193,12 +193,13 @@ struct ath5k_softc {
 	dma_addr_t		desc_daddr;	/* DMA (physical) address */
 	size_t			desc_len;	/* size of TX/RX descriptors */
 
-	DECLARE_BITMAP(status, 5);
+	DECLARE_BITMAP(status, 6);
 #define ATH_STAT_INVALID	0		/* disable hardware accesses */
 #define ATH_STAT_MRRETRY	1		/* multi-rate retry support */
 #define ATH_STAT_PROMISC	2
 #define ATH_STAT_LEDSOFT	3		/* enable LED gpio status */
 #define ATH_STAT_STARTED	4		/* opened & irqs enabled */
+#define ATH_STAT_2G_DISABLED	5		/* multiband radio without 2G */
 
 	unsigned int		filter_flags;	/* HW flags, AR5K_RX_FILTER_* */
 	struct ieee80211_channel *curchan;	/* current h/w channel */