brcmfmac: Add RSDB support.

Broadcom devices with a single 802.11 core can work on two band
concurrently using VSDB feature, ie. Virtual Simultaneous Dual-Band.
For devices that are fitted with two 802.11 cores and RF paths the
driver should support a firmware feature called RSDB, which stands
for Real Simultaneous Dual-Band. RSDB works almost autonomously in
firmware except for AP config. When the device supports RSDB then
the interface should not be brought down when configuring it,
otherwise the link (if configured) on the other interface will be
lost.
Reviewed-by: NArend Van Spriel <arend@broadcom.com>
Reviewed-by: NPieter-Paul Giesberts <pieterpg@broadcom.com>
Signed-off-by: NHante Meuleman <meuleman@broadcom.com>
Signed-off-by: NArend van Spriel <arend@broadcom.com>
[kvalo@codeaurora.org: changed the commit log based on discussion]
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c

@@ -4183,7 +4183,9 @@ brcmf_cfg80211_start_ap(struct wiphy *wiphy, struct net_device *ndev,
 			}
 		}
 
-		if (dev_role == NL80211_IFTYPE_AP) {
+		if ((dev_role == NL80211_IFTYPE_AP) &&
+		    ((ifp->ifidx == 0) ||
+		     !brcmf_feat_is_enabled(ifp, BRCMF_FEAT_RSDB))) {
 			err = brcmf_fil_cmd_int_set(ifp, BRCMF_C_DOWN, 1);
 			if (err < 0) {
 				brcmf_err("BRCMF_C_DOWN error %d\n", err);

drivers/net/wireless/broadcom/brcm80211/brcmfmac/feature.c

@@ -137,6 +137,7 @@ void brcmf_feat_attach(struct brcmf_pub *drvr)
 	if (drvr->bus_if->chip != BRCM_CC_43362_CHIP_ID)
 		brcmf_feat_iovar_int_set(ifp, BRCMF_FEAT_MBSS, "mbss", 0);
 	brcmf_feat_iovar_int_get(ifp, BRCMF_FEAT_P2P, "p2p");
+	brcmf_feat_iovar_int_get(ifp, BRCMF_FEAT_RSDB, "rsdb_mode");
 
 	if (brcmf_feature_disable) {
 		brcmf_dbg(INFO, "Features: 0x%02x, disable: 0x%02x\n",

drivers/net/wireless/broadcom/brcm80211/brcmfmac/feature.h

@@ -24,13 +24,16 @@
  * PNO: preferred network offload.
  * WOWL: Wake-On-WLAN.
  * P2P: peer-to-peer
+ * RSDB: Real Simultaneous Dual Band
  */
 #define BRCMF_FEAT_LIST \
 	BRCMF_FEAT_DEF(MBSS) \
 	BRCMF_FEAT_DEF(MCHAN) \
 	BRCMF_FEAT_DEF(PNO) \
 	BRCMF_FEAT_DEF(WOWL) \
-	BRCMF_FEAT_DEF(P2P)
+	BRCMF_FEAT_DEF(P2P) \
+	BRCMF_FEAT_DEF(RSDB)
+
 /*
  * Quirks:
  *