This patch adds support to set transmit power setting type and transmit
power level attributes to NL80211_CMD_SET_STATION in order to facilitate
adjusting the transmit power level of a station associated to the AP.

The added attributes allow selection of automatic and limited transmit
power level, with the level defined in mBm format.

Signed-off-by: Ashok Raj Nagarajan <arnag...@qti.qualcomm.com>
---
v2:
        - refactor the shared code
        - "keep what you had" using STATION_PARAM_APPLY_* BIT
        - feature flag to let the user know if this feature is supported or not 
(Johannes)
v3:
        - fix the limitation of changing the txpwr after association (Ben 
Greear)

 include/net/cfg80211.h       |  6 ++++++
 include/uapi/linux/nl80211.h | 15 ++++++++++++++
 net/wireless/nl80211.c       | 48 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 69 insertions(+)

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 814be4b..661e0ea 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -808,6 +808,7 @@ enum station_parameters_apply_mask {
        STATION_PARAM_APPLY_UAPSD = BIT(0),
        STATION_PARAM_APPLY_CAPABILITY = BIT(1),
        STATION_PARAM_APPLY_PLINK_STATE = BIT(2),
+       STATION_PARAM_APPLY_STA_TXPOWER = BIT(3),
 };
 
 /**
@@ -849,6 +850,10 @@ enum station_parameters_apply_mask {
  * @opmode_notif: operating mode field from Operating Mode Notification
  * @opmode_notif_used: information if operating mode field is used
  * @support_p2p_ps: information if station supports P2P PS mechanism
+ * @txpwr: tx power (in mBm) to be used for sending data traffic. If tx power
+ *     is not provided, the default per-interface tx power setting will be
+ *     overriding. Driver should be picking up the lowest tx power, either tx
+ *     power per-interface or per-station.
  */
 struct station_parameters {
        const u8 *supported_rates;
@@ -876,6 +881,7 @@ struct station_parameters {
        u8 opmode_notif;
        bool opmode_notif_used;
        int support_p2p_ps;
+       u16 txpwr;
 };
 
 /**
diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index 6b76e3b..de2f72c 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -1980,6 +1980,15 @@ enum nl80211_commands {
  * @NL80211_ATTR_BSSID: The BSSID of the AP. Note that %NL80211_ATTR_MAC is 
also
  *     used in various commands/events for specifying the BSSID.
  *
+ * @NL80211_ATTR_STA_TX_POWER_SETTING: Transmit power setting type (u32) for
+ *     station associated with the AP. See &enum nl80211_tx_power_setting for
+ *     possible values.
+ * @NL80211_ATTR_STA_TX_POWER: Transmit power level (u32) in mBm units. This
+ *     allows to set Tx power for a station. If this attribute is not included,
+ *     the default per-interface tx power setting will be overriding. Driver
+ *     should be picking up the lowest tx power, either tx power per-interface
+ *     or per-station.
+ *
  * @NUM_NL80211_ATTR: total number of nl80211_attrs available
  * @NL80211_ATTR_MAX: highest attribute number currently defined
  * @__NL80211_ATTR_AFTER_LAST: internal use
@@ -2386,6 +2395,9 @@ enum nl80211_attrs {
 
        NL80211_ATTR_BSSID,
 
+       NL80211_ATTR_STA_TX_POWER_SETTING,
+       NL80211_ATTR_STA_TX_POWER,
+
        /* add attributes here, update the policy in nl80211.c */
 
        __NL80211_ATTR_AFTER_LAST,
@@ -4697,6 +4709,8 @@ enum nl80211_feature_flags {
  *     configuration (AP/mesh) with VHT rates.
  * @NL80211_EXT_FEATURE_FILS_STA: This driver supports Fast Initial Link Setup
  *     with user space SME (NL80211_CMD_AUTHENTICATE) in station mode.
+ * @NL80211_EXT_FEATURE_STA_TX_PWR: This driver supports controlling tx power
+ *     to a station.
  *
  * @NUM_NL80211_EXT_FEATURES: number of extended features.
  * @MAX_NL80211_EXT_FEATURES: highest extended feature index.
@@ -4712,6 +4726,7 @@ enum nl80211_ext_feature_index {
        NL80211_EXT_FEATURE_BEACON_RATE_HT,
        NL80211_EXT_FEATURE_BEACON_RATE_VHT,
        NL80211_EXT_FEATURE_FILS_STA,
+       NL80211_EXT_FEATURE_STA_TX_PWR,
 
        /* add new features before the definition below */
        NUM_NL80211_EXT_FEATURES,
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index ef5eff93..701c08a 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -246,6 +246,8 @@ enum nl80211_multicast_groups {
        [NL80211_ATTR_STA_SUPPORTED_RATES] = { .type = NLA_BINARY,
                                               .len = NL80211_MAX_SUPP_RATES },
        [NL80211_ATTR_STA_PLINK_ACTION] = { .type = NLA_U8 },
+       [NL80211_ATTR_STA_TX_POWER_SETTING] = { .type = NLA_U32 },
+       [NL80211_ATTR_STA_TX_POWER] = { .type = NLA_U32 },
        [NL80211_ATTR_STA_VLAN] = { .type = NLA_U32 },
        [NL80211_ATTR_MNTR_FLAGS] = { /* NLA_NESTED can't be empty */ },
        [NL80211_ATTR_MESH_ID] = { .type = NLA_BINARY,
@@ -4755,6 +4757,40 @@ static int nl80211_set_station_tdls(struct genl_info 
*info,
        return nl80211_parse_sta_wme(info, params);
 }
 
+static int nl80211_parse_sta_txpower_setting(struct genl_info *info,
+                                            struct station_parameters *params)
+{
+       struct cfg80211_registered_device *rdev = info->user_ptr[0];
+       enum nl80211_tx_power_setting type;
+       int idx;
+
+       if (!rdev->ops->set_tx_power ||
+           !wiphy_ext_feature_isset(&rdev->wiphy,
+                                    NL80211_EXT_FEATURE_STA_TX_PWR))
+               return -EOPNOTSUPP;
+
+       idx = NL80211_ATTR_STA_TX_POWER_SETTING;
+       type = nla_get_u32(info->attrs[idx]);
+
+       if (!info->attrs[NL80211_ATTR_STA_TX_POWER] &&
+           (type != NL80211_TX_POWER_AUTOMATIC))
+               return -EINVAL;
+
+       if (type != NL80211_TX_POWER_AUTOMATIC) {
+               if (type == NL80211_TX_POWER_LIMITED) {
+                       idx = NL80211_ATTR_STA_TX_POWER;
+                       params->txpwr = nla_get_u32(info->attrs[idx]);
+               } else {
+                       return -EINVAL;
+               }
+       } else {
+               params->txpwr = 0;
+       }
+       params->sta_modify_mask |= STATION_PARAM_APPLY_STA_TXPOWER;
+
+       return 0;
+}
+
 static int nl80211_set_station(struct sk_buff *skb, struct genl_info *info)
 {
        struct cfg80211_registered_device *rdev = info->user_ptr[0];
@@ -4854,6 +4890,12 @@ static int nl80211_set_station(struct sk_buff *skb, 
struct genl_info *info)
                params.local_pm = pm;
        }
 
+       if (info->attrs[NL80211_ATTR_STA_TX_POWER_SETTING]) {
+               err = nl80211_parse_sta_txpower_setting(info, &params);
+               if (err)
+                       return err;
+       }
+
        /* Include parameters for TDLS peer (will check later) */
        err = nl80211_set_station_tdls(info, &params);
        if (err)
@@ -4981,6 +5023,12 @@ static int nl80211_new_station(struct sk_buff *skb, 
struct genl_info *info)
                        return -EINVAL;
        }
 
+       if (info->attrs[NL80211_ATTR_STA_TX_POWER_SETTING]) {
+               err = nl80211_parse_sta_txpower_setting(info, &params);
+               if (err)
+                       return err;
+       }
+
        err = nl80211_parse_sta_channel_info(info, &params);
        if (err)
                return err;
-- 
1.9.1

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