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[v2] hostapd: add Transmit Power Envelope IE

Message ID 1448284226-8036-1-git-send-email-rmanohar@qti.qualcomm.com
State Accepted
Headers show

Commit Message

Rajkumar Manoharan Nov. 23, 2015, 1:10 p.m. UTC 
Add Transmit Power Envelope element defined in
IEEE P802.11-REVmc/D4.3, 8.4.2.161.

Signed-off-by: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>
---
v2:
 * "VHT" removed from the name
 * removed channel switch conditions
 * handled 80+80/160 MHz case
 * corrected max tx power calculation

 src/ap/beacon.c         |   2 +
 src/ap/ieee802_11.h     |   1 +
 src/ap/ieee802_11_vht.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 106 insertions(+)

Comments

Jouni Malinen Nov. 26, 2015, 7:03 p.m. UTC | #1 
On Mon, Nov 23, 2015 at 06:40:26PM +0530, Rajkumar Manoharan wrote:
> Add Transmit Power Envelope element defined in
> IEEE P802.11-REVmc/D4.3, 8.4.2.161.

Thanks, applied.

> diff --git a/src/ap/ieee802_11_vht.c b/src/ap/ieee802_11_vht.c
> +u8 * hostapd_eid_vht_txpwr_env(struct hostapd_data *hapd, u8 *eid)

> +	max_tx_power = chan->max_tx_power - local_pwr_constraint;
> +
> +	/*
> +	 * Local Maximum Transmit power is encoded as 2's complement
> +	 * with a 0.5 dB step
> +	 */
> +	max_tx_power = ~(max_tx_power * 2) + 1;

Though, this does not look correct.. That would mess up positive values
pretty badly. I think I fixed this, but anyway, please take a look at
send a patch to update this, if needed.

> +	*eid++ = WLAN_EID_VHT_TRANSMIT_POWER_ENVELOPE;
> +	*eid++ = 4;

That length value is not correct since this is now variable length:

> +	/*
> +	 * Max Transmit Power count and
> +	 * Max Transmit Power units = 0 (EIRP)
> +	 */
> +	*eid++ = tx_pwr_count;
> +
> +	i = 0;
> +	while (i++ <= tx_pwr_count)
> +		*eid++ = max_tx_power;

Here.. Fixed the length field to match.
Rajkumar Manoharan Nov. 27, 2015, 9:38 a.m. UTC | #2 
On Thu, Nov 26, 2015 at 09:03:22PM +0200, Jouni Malinen wrote:
> On Mon, Nov 23, 2015 at 06:40:26PM +0530, Rajkumar Manoharan wrote:
> > Add Transmit Power Envelope element defined in
> > IEEE P802.11-REVmc/D4.3, 8.4.2.161.
> 
> Thanks, applied.
>
> > diff --git a/src/ap/ieee802_11_vht.c b/src/ap/ieee802_11_vht.c
> > +u8 * hostapd_eid_vht_txpwr_env(struct hostapd_data *hapd, u8 *eid)
> 
> > +	max_tx_power = chan->max_tx_power - local_pwr_constraint;
> > +
> > +	/*
> > +	 * Local Maximum Transmit power is encoded as 2's complement
> > +	 * with a 0.5 dB step
> > +	 */
> > +	max_tx_power = ~(max_tx_power * 2) + 1;
> 
> Though, this does not look correct.. That would mess up positive values
> pretty badly. I think I fixed this, but anyway, please take a look at
> send a patch to update this, if needed.
>
your change looks much better that above logic. It also takes care of
special cases.

> > +	*eid++ = WLAN_EID_VHT_TRANSMIT_POWER_ENVELOPE;
> > +	*eid++ = 4;
> 
> That length value is not correct since this is now variable length:
> 
oops.. my bad.
> > +	/*
> > +	 * Max Transmit Power count and
> > +	 * Max Transmit Power units = 0 (EIRP)
> > +	 */
> > +	*eid++ = tx_pwr_count;
> > +
> > +	i = 0;
> > +	while (i++ <= tx_pwr_count)
> > +		*eid++ = max_tx_power;
> 
> Here.. Fixed the length field to match.
>
Sorry for the inconvenience.. Thanks a lot.

-Rajkumar
diff mbox

Patch

diff --git a/src/ap/beacon.c b/src/ap/beacon.c
index 5f65b7d..d4054cb 100644
--- a/src/ap/beacon.c
+++ b/src/ap/beacon.c
@@ -481,6 +481,7 @@  static u8 * hostapd_gen_probe_resp(struct hostapd_data *hapd,
 	if (hapd->iconf->ieee80211ac && !hapd->conf->disable_11ac) {
 		pos = hostapd_eid_vht_capabilities(hapd, pos);
 		pos = hostapd_eid_vht_operation(hapd, pos);
+		pos = hostapd_eid_vht_txpwr_env(hapd, pos);
 		pos = hostapd_eid_wb_chsw_wrapper(hapd, pos);
 	}
 	if (hapd->conf->vendor_vht)
@@ -1096,6 +1097,7 @@  int ieee802_11_build_ap_params(struct hostapd_data *hapd,
 	if (hapd->iconf->ieee80211ac && !hapd->conf->disable_11ac) {
 		tailpos = hostapd_eid_vht_capabilities(hapd, tailpos);
 		tailpos = hostapd_eid_vht_operation(hapd, tailpos);
+		tailpos = hostapd_eid_vht_txpwr_env(hapd, tailpos);
 		tailpos = hostapd_eid_wb_chsw_wrapper(hapd, tailpos);
 	}
 	if (hapd->conf->vendor_vht)
diff --git a/src/ap/ieee802_11.h b/src/ap/ieee802_11.h
index a2dd132..4788e6b 100644
--- a/src/ap/ieee802_11.h
+++ b/src/ap/ieee802_11.h
@@ -54,6 +54,7 @@  u8 * hostapd_eid_vht_capabilities(struct hostapd_data *hapd, u8 *eid);
 u8 * hostapd_eid_vht_operation(struct hostapd_data *hapd, u8 *eid);
 u8 * hostapd_eid_vendor_vht(struct hostapd_data *hapd, u8 *eid);
 u8 * hostapd_eid_wb_chsw_wrapper(struct hostapd_data *hapd, u8 *eid);
+u8 * hostapd_eid_vht_txpwr_env(struct hostapd_data *hapd, u8 *eid);
 
 int hostapd_ht_operation_update(struct hostapd_iface *iface);
 void ieee802_11_send_sa_query_req(struct hostapd_data *hapd,
diff --git a/src/ap/ieee802_11_vht.c b/src/ap/ieee802_11_vht.c
index 8d2c428..59522a7 100644
--- a/src/ap/ieee802_11_vht.c
+++ b/src/ap/ieee802_11_vht.c
@@ -17,6 +17,7 @@ 
 #include "sta_info.h"
 #include "beacon.h"
 #include "ieee802_11.h"
+#include "dfs.h"
 
 
 u8 * hostapd_eid_vht_capabilities(struct hostapd_data *hapd, u8 *eid)
@@ -184,6 +185,108 @@  u8 * hostapd_eid_wb_chsw_wrapper(struct hostapd_data *hapd, u8 *eid)
 }
 
 
+u8 * hostapd_eid_vht_txpwr_env(struct hostapd_data *hapd, u8 *eid)
+{
+	struct hostapd_iface *iface = hapd->iface;
+	struct hostapd_config *iconf = iface->conf;
+	struct hostapd_hw_modes *mode = iface->current_mode;
+	struct hostapd_channel_data *chan;
+	int dfs, i;
+	u8 channel, max_tx_power, tx_pwr_count, local_pwr_constraint;
+
+	if (!mode)
+		return eid;
+
+	if (ieee80211_freq_to_chan(iface->freq, &channel) ==
+	    NUM_HOSTAPD_MODES)
+		return eid;
+
+	for (i = 0; i < mode->num_channels; i++) {
+		if (mode->channels[i].freq == iface->freq)
+			break;
+	}
+	if (i == mode->num_channels)
+		return eid;
+
+	switch (iface->conf->vht_oper_chwidth) {
+	case VHT_CHANWIDTH_USE_HT:
+		if (iconf->secondary_channel == 0) {
+			/* Max Transmit Power count = 0 (20MHz) */
+			tx_pwr_count = 0;
+		} else {
+			/* Max Transmit Power count = 1 (20, 40MHz) */
+			tx_pwr_count = 1;
+		}
+		break;
+	case VHT_CHANWIDTH_80MHZ:
+		/* Max Transmit Power count = 2 (20, 40 and 80MHz) */
+		tx_pwr_count = 2;
+		break;
+	case VHT_CHANWIDTH_80P80MHZ:
+	case VHT_CHANWIDTH_160MHZ:
+		/* Max Transmit Power count = 3 (20, 40, 80, 160/80+80MHz) */
+		tx_pwr_count = 3;
+		break;
+	default:
+		return eid;
+	}
+
+	/*
+	 * Below local_pwr_constraint logic is referred from
+	 * hostapd_eid_pwr_constraint.
+	 *
+	 * Check if DFS is required by regulatory.
+	 */
+	dfs = hostapd_is_dfs_required(hapd->iface);
+	if (dfs < 0)
+		dfs = 0;
+
+	/*
+	 * In order to meet regulations when TPC is not implemented using
+	 * a transmit power that is below the legal maximum (including any
+	 * mitigation factor) should help. In this case, indicate 3 dB below
+	 * maximum allowed transmit power.
+	 */
+	if (hapd->iconf->local_pwr_constraint == -1)
+		local_pwr_constraint = (dfs == 0) ? 0 : 3;
+	else
+		local_pwr_constraint = hapd->iconf->local_pwr_constraint;
+
+	/*
+	 * A STA that is not an AP shall use a transmit power less than or
+	 * equal to the local maximum transmit power level for the channel.
+	 * The local maximum transmit power can be calculated from the formula:
+	 * local max TX pwr = max TX pwr - local pwr constraint
+	 * Where max TX pwr is maximum transmit power level specified for
+	 * channel in Country element and local pwr constraint is specified
+	 * for channel in this Power Constraint element.
+	 */
+	chan = &mode->channels[i];
+	max_tx_power = chan->max_tx_power - local_pwr_constraint;
+
+	/*
+	 * Local Maximum Transmit power is encoded as 2's complement
+	 * with a 0.5 dB step
+	 */
+	max_tx_power = ~(max_tx_power * 2) + 1;
+
+	*eid++ = WLAN_EID_VHT_TRANSMIT_POWER_ENVELOPE;
+	*eid++ = 4;
+
+	/*
+	 * Max Transmit Power count and
+	 * Max Transmit Power units = 0 (EIRP)
+	 */
+	*eid++ = tx_pwr_count;
+
+	i = 0;
+	while (i++ <= tx_pwr_count)
+		*eid++ = max_tx_power;
+
+	return eid;
+}
+
+
 u16 copy_sta_vht_capab(struct hostapd_data *hapd, struct sta_info *sta,
 		       const u8 *vht_capab)
 {