[PATCH v6 0/3] Antenna configuration API

[PATCH v6 0/3] Antenna configuration API

[Bruno Randolf]

I'm resending the Antenna API series with the one fix which was requested last
time. No we disallow antenna configuration if the wifi is running, to make life
easier for 802.11n devices, which might have to recalculate chainmasks and HT
settings based on the available antennas. I hope this makes it acceptable for
merging now.

bruno

---

Bruno Randolf (3):
      cfg80211: Add nl80211 antenna configuration
      mac80211: Add antenna configuration
      ath5k: Add support for antenna configuration


 drivers/net/wireless/ath/ath5k/base.c |   32 +++++++++++++++++++++
 include/linux/nl80211.h               |   25 +++++++++++++++++
 include/net/cfg80211.h                |    3 ++
 include/net/mac80211.h                |    2 +
 net/mac80211/cfg.c                    |   19 +++++++++++++
 net/mac80211/driver-ops.h             |   23 +++++++++++++++
 net/mac80211/driver-trace.h           |   50 +++++++++++++++++++++++++++++++++
 net/wireless/nl80211.c                |   31 ++++++++++++++++++++
 8 files changed, 184 insertions(+), 1 deletions(-)

-- 
Signature

[PATCH v6 1/3] cfg80211: Add nl80211 antenna configuration

[Bruno Randolf]

Allow setting of TX and RX antenna configuration via nl80211.

The antenna configuration is defined as a bitmap of allowed antennas to use.
This API can be used to mask out antennas which are not attached or should not
be used for other reasons like regulatory concerns or special setups.

Separate bitmaps are used for RX and TX to allow configuring different antennas
for receiving and transmitting. The bitmap is 8 bit long, each bit representing
one antenna, starting with antenna 1 at the first bit. If an antenna bit is
set, this means the driver is allowed to use this antenna for RX or TX
respectively; if the bit is not set the hardware is not allowed to use this
antenna.

Using bitmaps has the benefit of allowing for a flexible configuration
interface which can support many different configurations and which can be used
for 802.11n as well as non-802.11n devices. Instead of relying on some hardware
specific assumptions, drivers can use this information to know which antennas
are actually attached to the system and derive their capabilities based on
that.

802.11n devices should enable or disable chains, based on which antennas are
present (If all antennas belonging to a particular chain are disabled, the
entire chain should be disabled). HT capabilities (like STBC, TX Beamforming,
Antenna selection) should be calculated based on the available chains after
applying the antenna masks. Should a 802.11n device have diversity antennas
attached to one of their chains, diversity can be enabled or disabled based on
the antenna information.

Non-802.11n drivers can use the antenna masks to enable or disable antenna
diversity.

While covering chainmasks for 802.11n and the standard "legacy" modes "fixed
antenna 1", "fixed antenna 2" and "diversity" this API also allows more rare,
but useful configurations as follows:

1) Send on antenna 1, receive on antenna 2 (or vice versa). This can be used to
have a low gain antenna for TX in order to keep within the regulatory
constraints and a high gain antenna for RX in order to receive weaker signals
("speak softly, but listen harder"). This can be useful for building long-shot
outdoor links. Another usage of this setup is having a low-noise pre-amplifier
on antenna 1 and a power amplifier on the other antenna. This way transmit
noise is mostly kept out of the low noise receive channel.
(This would be bitmaps: tx 1 rx 2).

2) Another similar setup is: Use RX diversity on both antennas, but always send
on antenna 1. Again that would allow us to benefit from a higher gain RX
antenna, while staying within the legal limits.
(This would be: tx 0 rx 3).

3) And finally there can be special experimental setups in research and
development even with pre 802.11n hardware where more than 2 antennas are
available. It's good to keep the API simple, yet flexible.

Signed-off-by: Bruno Randolf <br1@einfach.org>
---
 include/linux/nl80211.h |   25 +++++++++++++++++++++++++
 include/net/cfg80211.h  |    3 +++
 net/wireless/nl80211.c  |   31 ++++++++++++++++++++++++++++++-
 3 files changed, 58 insertions(+), 1 deletions(-)

diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index 0edb256..276fec0 100644
--- a/include/linux/nl80211.h
+++ b/include/linux/nl80211.h
@@ -804,6 +804,28 @@ enum nl80211_commands {
  * @NL80211_ATTR_SUPPORT_IBSS_RSN: The device supports IBSS RSN, which mostly
  *	means support for per-station GTKs.
  *
+ * @NL80211_ATTR_WIPHY_ANTENNA_TX: Bitmap of allowed antennas for transmitting.
+ *	This can be used to mask out antennas which are not attached or should
+ *	not be used for transmitting. If an antenna is not selected in this
+ *	bitmap the hardware is not allowed to transmit on this antenna.
+ *
+ *	Each bit represents one antenna, starting with antenna 1 at the first
+ *	bit. Depending on which antennas are selected in the bitmap, 802.11n
+ *	drivers can derive which chainmasks to use (if all antennas belonging to
+ *	a particular chain are disabled this chain should be disabled) and if
+ *	a chain has diversity antennas wether diversity should be used or not.
+ *	HT capabilities (STBC, TX Beamforming, Antenna selection) can be
+ *	derived from the available chains after applying the antenna mask.
+ *	Non-802.11n drivers can derive wether to use diversity or not.
+ *	Drivers may reject configurations or RX/TX mask combinations they cannot
+ *	support by returning -EINVAL.
+ *
+ * @NL80211_ATTR_WIPHY_ANTENNA_RX: Bitmap of allowed antennas for receiving.
+ *	This can be used to mask out antennas which are not attached or should
+ *	not be used for receiving. If an antenna is not selected in this bitmap
+ *	the hardware should not be configured to receive on this antenna.
+ *	For a more detailed descripton see @NL80211_ATTR_WIPHY_ANTENNA_TX.
+ *
  * @NL80211_ATTR_MAX: highest attribute number currently defined
  * @__NL80211_ATTR_AFTER_LAST: internal use
  */
@@ -973,6 +995,9 @@ enum nl80211_attrs {
 
 	NL80211_ATTR_SUPPORT_IBSS_RSN,
 
+	NL80211_ATTR_WIPHY_ANTENNA_TX,
+	NL80211_ATTR_WIPHY_ANTENNA_RX,
+
 	/* add attributes here, update the policy in nl80211.c */
 
 	__NL80211_ATTR_AFTER_LAST,
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 2a7936d..9b88fff 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -1304,6 +1304,9 @@ struct cfg80211_ops {
 	void	(*mgmt_frame_register)(struct wiphy *wiphy,
 				       struct net_device *dev,
 				       u16 frame_type, bool reg);
+
+	int	(*set_antenna)(struct wiphy *wiphy, u8 tx_ant, u8 rx_ant);
+	int	(*get_antenna)(struct wiphy *wiphy, u8 *tx_ant, u8 *rx_ant);
 };
 
 /*
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index c506241..2343fde 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -166,7 +166,11 @@ static const struct nla_policy nl80211_policy[NL80211_ATTR_MAX+1] = {
 
 	[NL80211_ATTR_WIPHY_TX_POWER_SETTING] = { .type = NLA_U32 },
 	[NL80211_ATTR_WIPHY_TX_POWER_LEVEL] = { .type = NLA_U32 },
+
 	[NL80211_ATTR_FRAME_TYPE] = { .type = NLA_U16 },
+
+	[NL80211_ATTR_WIPHY_ANTENNA_TX] = { .type = NLA_U8 },
+	[NL80211_ATTR_WIPHY_ANTENNA_RX] = { .type = NLA_U8 },
 };
 
 /* policy for the key attributes */
@@ -526,7 +530,6 @@ static int nl80211_send_wiphy(struct sk_buff *msg, u32 pid, u32 seq, int flags,
 		    dev->wiphy.rts_threshold);
 	NLA_PUT_U8(msg, NL80211_ATTR_WIPHY_COVERAGE_CLASS,
 		    dev->wiphy.coverage_class);
-
 	NLA_PUT_U8(msg, NL80211_ATTR_MAX_NUM_SCAN_SSIDS,
 		   dev->wiphy.max_scan_ssids);
 	NLA_PUT_U16(msg, NL80211_ATTR_MAX_SCAN_IE_LEN,
@@ -545,6 +548,16 @@ static int nl80211_send_wiphy(struct sk_buff *msg, u32 pid, u32 seq, int flags,
 	if (dev->wiphy.flags & WIPHY_FLAG_CONTROL_PORT_PROTOCOL)
 		NLA_PUT_FLAG(msg, NL80211_ATTR_CONTROL_PORT_ETHERTYPE);
 
+	if (dev->ops->get_antenna) {
+		u8 tx_ant = 0, rx_ant = 0;
+		int res;
+		res = dev->ops->get_antenna(&dev->wiphy, &tx_ant, &rx_ant);
+		if (!res) {
+			NLA_PUT_U8(msg, NL80211_ATTR_WIPHY_ANTENNA_TX, tx_ant);
+			NLA_PUT_U8(msg, NL80211_ATTR_WIPHY_ANTENNA_RX, rx_ant);
+		}
+	}
+
 	nl_modes = nla_nest_start(msg, NL80211_ATTR_SUPPORTED_IFTYPES);
 	if (!nl_modes)
 		goto nla_put_failure;
@@ -1024,6 +1037,22 @@ static int nl80211_set_wiphy(struct sk_buff *skb, struct genl_info *info)
 			goto bad_res;
 	}
 
+	if (info->attrs[NL80211_ATTR_WIPHY_ANTENNA_TX] &&
+	    info->attrs[NL80211_ATTR_WIPHY_ANTENNA_RX]) {
+		u8 tx_ant, rx_ant;
+		if (!rdev->ops->set_antenna) {
+			result = -EOPNOTSUPP;
+			goto bad_res;
+		}
+
+		tx_ant = nla_get_u8(info->attrs[NL80211_ATTR_WIPHY_ANTENNA_TX]);
+		rx_ant = nla_get_u8(info->attrs[NL80211_ATTR_WIPHY_ANTENNA_RX]);
+
+		result = rdev->ops->set_antenna(&rdev->wiphy, tx_ant, rx_ant);
+		if (result)
+			goto bad_res;
+	}
+
 	changed = 0;
 
 	if (info->attrs[NL80211_ATTR_WIPHY_RETRY_SHORT]) {

Re: [PATCH v6 1/3] cfg80211: Add nl80211 antenna configuration

[Luis R. Rodriguez]

On Thu, Nov 4, 2010 at 11:53 PM, Bruno Randolf <br1@einfach.org> wrote:
> Allow setting of TX and RX antenna configuration via nl80211.
>
> The antenna configuration is defined as a bitmap of allowed antennas to use.
> This API can be used to mask out antennas which are not attached or should not
> be used for other reasons like regulatory concerns or special setups.
>
> Separate bitmaps are used for RX and TX to allow configuring different antennas
> for receiving and transmitting. The bitmap is 8 bit long, each bit representing
> one antenna, starting with antenna 1 at the first bit. If an antenna bit is
> set, this means the driver is allowed to use this antenna for RX or TX
> respectively; if the bit is not set the hardware is not allowed to use this
> antenna.
>
> Using bitmaps has the benefit of allowing for a flexible configuration
> interface which can support many different configurations and which can be used
> for 802.11n as well as non-802.11n devices. Instead of relying on some hardware
> specific assumptions, drivers can use this information to know which antennas
> are actually attached to the system and derive their capabilities based on
> that.
>
> 802.11n devices should enable or disable chains, based on which antennas are
> present (If all antennas belonging to a particular chain are disabled, the
> entire chain should be disabled). HT capabilities (like STBC, TX Beamforming,
> Antenna selection) should be calculated based on the available chains after
> applying the antenna masks. Should a 802.11n device have diversity antennas
> attached to one of their chains, diversity can be enabled or disabled based on
> the antenna information.
>
> Non-802.11n drivers can use the antenna masks to enable or disable antenna
> diversity.
>
> While covering chainmasks for 802.11n and the standard "legacy" modes "fixed
> antenna 1", "fixed antenna 2" and "diversity" this API also allows more rare,
> but useful configurations as follows:
>
> 1) Send on antenna 1, receive on antenna 2 (or vice versa). This can be used to
> have a low gain antenna for TX in order to keep within the regulatory
> constraints and a high gain antenna for RX in order to receive weaker signals
> ("speak softly, but listen harder"). This can be useful for building long-shot
> outdoor links. Another usage of this setup is having a low-noise pre-amplifier
> on antenna 1 and a power amplifier on the other antenna. This way transmit
> noise is mostly kept out of the low noise receive channel.
> (This would be bitmaps: tx 1 rx 2).
>
> 2) Another similar setup is: Use RX diversity on both antennas, but always send
> on antenna 1. Again that would allow us to benefit from a higher gain RX
> antenna, while staying within the legal limits.
> (This would be: tx 0 rx 3).
>
> 3) And finally there can be special experimental setups in research and
> development even with pre 802.11n hardware where more than 2 antennas are
> available. It's good to keep the API simple, yet flexible.
>
> Signed-off-by: Bruno Randolf <br1@einfach.org>

Can you please make the TX/RX antenna stuff 32 bits so that way we
never run out? 8-bits will get us far but better to not be sorry about
this later.

  Luis

[PATCH v6 2/3] mac80211: Add antenna configuration

[Bruno Randolf]

Allow antenna configuration by calling driver's function for it.

We disallow antenna configuration if the wihpy is already running, mainly to
make life easier for 802.11n drivers which need to recalculate HT capabilites.

Signed-off-by: Bruno Randolf <br1@einfach.org>
---
 include/net/mac80211.h      |    2 ++
 net/mac80211/cfg.c          |   19 ++++++++++++++++
 net/mac80211/driver-ops.h   |   23 ++++++++++++++++++++
 net/mac80211/driver-trace.h |   50 +++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 94 insertions(+), 0 deletions(-)

diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 9fdf982..b14dd7d 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -1793,6 +1793,8 @@ struct ieee80211_ops {
 	void (*channel_switch)(struct ieee80211_hw *hw,
 			       struct ieee80211_channel_switch *ch_switch);
 	int (*napi_poll)(struct ieee80211_hw *hw, int budget);
+	int (*set_antenna)(struct ieee80211_hw *hw, u8 tx_ant, u8 rx_ant);
+	int (*get_antenna)(struct ieee80211_hw *hw, u8 *tx_ant, u8 *rx_ant);
 };
 
 /**
diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 18bd0e5..ae1e98e 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -1621,6 +1621,23 @@ static void ieee80211_mgmt_frame_register(struct wiphy *wiphy,
 	ieee80211_queue_work(&local->hw, &local->reconfig_filter);
 }
 
+static int ieee80211_set_antenna(struct wiphy *wiphy, u8 tx_ant, u8 rx_ant)
+{
+	struct ieee80211_local *local = wiphy_priv(wiphy);
+
+	if (local->started)
+		return -EOPNOTSUPP;
+
+	return drv_set_antenna(local, tx_ant, rx_ant);
+}
+
+static int ieee80211_get_antenna(struct wiphy *wiphy, u8 *tx_ant, u8 *rx_ant)
+{
+	struct ieee80211_local *local = wiphy_priv(wiphy);
+
+	return drv_get_antenna(local, tx_ant, rx_ant);
+}
+
 struct cfg80211_ops mac80211_config_ops = {
 	.add_virtual_intf = ieee80211_add_iface,
 	.del_virtual_intf = ieee80211_del_iface,
@@ -1673,4 +1690,6 @@ struct cfg80211_ops mac80211_config_ops = {
 	.mgmt_tx = ieee80211_mgmt_tx,
 	.set_cqm_rssi_config = ieee80211_set_cqm_rssi_config,
 	.mgmt_frame_register = ieee80211_mgmt_frame_register,
+	.set_antenna = ieee80211_set_antenna,
+	.get_antenna = ieee80211_get_antenna,
 };
diff --git a/net/mac80211/driver-ops.h b/net/mac80211/driver-ops.h
index 1698382..af48be8 100644
--- a/net/mac80211/driver-ops.h
+++ b/net/mac80211/driver-ops.h
@@ -428,4 +428,27 @@ static inline void drv_channel_switch(struct ieee80211_local *local,
 	trace_drv_return_void(local);
 }
 
+
+static inline int drv_set_antenna(struct ieee80211_local *local,
+				  u8 tx_ant, u8 rx_ant)
+{
+	int ret = -EOPNOTSUPP;
+	might_sleep();
+	if (local->ops->set_antenna)
+		ret = local->ops->set_antenna(&local->hw, tx_ant, rx_ant);
+	trace_drv_set_antenna(local, tx_ant, rx_ant, ret);
+	return ret;
+}
+
+static inline int drv_get_antenna(struct ieee80211_local *local,
+				  u8 *tx_ant, u8 *rx_ant)
+{
+	int ret = -EOPNOTSUPP;
+	might_sleep();
+	if (local->ops->get_antenna)
+		ret = local->ops->get_antenna(&local->hw, tx_ant, rx_ant);
+	trace_drv_get_antenna(local, *tx_ant, *rx_ant, ret);
+	return ret;
+}
+
 #endif /* __MAC80211_DRIVER_OPS */
diff --git a/net/mac80211/driver-trace.h b/net/mac80211/driver-trace.h
index 6831fb1..f7c0a0c 100644
--- a/net/mac80211/driver-trace.h
+++ b/net/mac80211/driver-trace.h
@@ -862,6 +862,56 @@ TRACE_EVENT(drv_channel_switch,
 	)
 );
 
+TRACE_EVENT(drv_set_antenna,
+	TP_PROTO(struct ieee80211_local *local, u8 tx_ant, u8 rx_ant, int ret),
+
+	TP_ARGS(local, tx_ant, rx_ant, ret),
+
+	TP_STRUCT__entry(
+		LOCAL_ENTRY
+		__field(u8, tx_ant)
+		__field(u8, rx_ant)
+		__field(int, ret)
+	),
+
+	TP_fast_assign(
+		LOCAL_ASSIGN;
+		__entry->tx_ant = tx_ant;
+		__entry->rx_ant = rx_ant;
+		__entry->ret = ret;
+	),
+
+	TP_printk(
+		LOCAL_PR_FMT " tx_ant:%d rx_ant:%d ret:%d",
+		LOCAL_PR_ARG, __entry->tx_ant, __entry->rx_ant, __entry->ret
+	)
+);
+
+TRACE_EVENT(drv_get_antenna,
+	TP_PROTO(struct ieee80211_local *local, u8 tx_ant, u8 rx_ant, int ret),
+
+	TP_ARGS(local, tx_ant, rx_ant, ret),
+
+	TP_STRUCT__entry(
+		LOCAL_ENTRY
+		__field(u8, tx_ant)
+		__field(u8, rx_ant)
+		__field(int, ret)
+	),
+
+	TP_fast_assign(
+		LOCAL_ASSIGN;
+		__entry->tx_ant = tx_ant;
+		__entry->rx_ant = rx_ant;
+		__entry->ret = ret;
+	),
+
+	TP_printk(
+		LOCAL_PR_FMT " tx_ant:%d rx_ant:%d ret:%d",
+		LOCAL_PR_ARG, __entry->tx_ant, __entry->rx_ant, __entry->ret
+	)
+);
+
 /*
  * Tracing for API calls that drivers call.
  */

[PATCH v6 3/3] ath5k: Add support for antenna configuration

[Bruno Randolf]

Support setting the antenna configuration via cfg/mac80211. At the moment only
allow the simple pre-defined configurations we already have (fixed antenna A/B
or diversity), but more advanced settings are possible to implement.

Signed-off-by: Bruno Randolf <br1@einfach.org>
---
 drivers/net/wireless/ath/ath5k/base.c |   32 ++++++++++++++++++++++++++++++++
 1 files changed, 32 insertions(+), 0 deletions(-)

diff --git a/drivers/net/wireless/ath/ath5k/base.c b/drivers/net/wireless/ath/ath5k/base.c
index 8251946..ba50a0b 100644
--- a/drivers/net/wireless/ath/ath5k/base.c
+++ b/drivers/net/wireless/ath/ath5k/base.c
@@ -3395,6 +3395,36 @@ static int ath5k_conf_tx(struct ieee80211_hw *hw, u16 queue,
 	return ret;
 }
 
+static int ath5k_set_antenna(struct ieee80211_hw *hw, u8 tx_ant, u8 rx_ant)
+{
+	struct ath5k_softc *sc = hw->priv;
+
+	if (tx_ant == 1 && rx_ant == 1)
+		ath5k_hw_set_antenna_mode(sc->ah, AR5K_ANTMODE_FIXED_A);
+	else if (tx_ant == 2 && rx_ant == 2)
+		ath5k_hw_set_antenna_mode(sc->ah, AR5K_ANTMODE_FIXED_B);
+	else if ((tx_ant & 3) == 3 && (rx_ant & 3) == 3)
+		ath5k_hw_set_antenna_mode(sc->ah, AR5K_ANTMODE_DEFAULT);
+	else
+		return -EINVAL;
+	return 0;
+}
+
+static int ath5k_get_antenna(struct ieee80211_hw *hw, u8 *tx_ant, u8 *rx_ant)
+{
+	struct ath5k_softc *sc = hw->priv;
+
+	switch (sc->ah->ah_ant_mode) {
+	case AR5K_ANTMODE_FIXED_A:
+		*tx_ant = 1; *rx_ant = 1; break;
+	case AR5K_ANTMODE_FIXED_B:
+		*tx_ant = 2; *rx_ant = 2; break;
+	case AR5K_ANTMODE_DEFAULT:
+		*tx_ant = 3; *rx_ant = 3; break;
+	}
+	return 0;
+}
+
 static const struct ieee80211_ops ath5k_hw_ops = {
 	.tx 		= ath5k_tx,
 	.start 		= ath5k_start,
@@ -3415,6 +3445,8 @@ static const struct ieee80211_ops ath5k_hw_ops = {
 	.sw_scan_start	= ath5k_sw_scan_start,
 	.sw_scan_complete = ath5k_sw_scan_complete,
 	.set_coverage_class = ath5k_set_coverage_class,
+	.set_antenna	= ath5k_set_antenna,
+	.get_antenna	= ath5k_get_antenna,
 };
 
 /********************\