cfg80211: return channel noise via survey API

This patch implements the NL80211_CMD_GET_SURVEY command and an get_survey()
ops that a driver can implement. The goal of this command is to allow a
drivers to report channel survey data (e.g. channel noise, channel
occupation).

For now, only the mechanism to report back channel noise has been
implemented.

In future, there will either be a survey-trigger command --- or the existing
scan-trigger command will be enhanced. This will allow user-space to
request survey for arbitrary channels.

Note: any driver that cannot report channel noise should not report
any value at all, e.g. made-up -92 dBm.

Signed-off-by: Holger Schurig <holgerschurig@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 68 insertions, 0 deletions

diff --git a/include/linux/nl80211.h b/include/linux/nl80211.h
index d2f276de9abe..45db17f81aa3 100644
--- a/include/linux/nl80211.h
+++ b/include/linux/nl80211.h
@@ -160,6 +160,11 @@
  * @NL80211_CMD_SCAN_ABORTED: scan was aborted, for unspecified reasons,
  *      partial scan results may be available
  *
+ * @NL80211_CMD_GET_SURVEY: get survey resuls, e.g. channel occupation
+ *      or noise level
+ * @NL80211_CMD_NEW_SURVEY_RESULTS: survey data notification (as a reply to
+ *      NL80211_CMD_GET_SURVEY and on the "scan" multicast group)
+ *
  * @NL80211_CMD_REG_CHANGE: indicates to userspace the regulatory domain
  *      has been changed and provides details of the request information
  *      that caused the change such as who initiated the regulatory request
@@ -341,6 +346,9 @@ enum nl80211_commands {
 
         NL80211_CMD_SET_WIPHY_NETNS,
 
+        NL80211_CMD_GET_SURVEY,
+        NL80211_CMD_NEW_SURVEY_RESULTS,
+
         /* add new commands above here */
 
         /* used to define NL80211_CMD_MAX below */
@@ -586,6 +594,10 @@ enum nl80211_commands {
  *
  * @NL80211_ATTR_4ADDR: Use 4-address frames on a virtual interface
  *
+ * @NL80211_ATTR_SURVEY_INFO: survey information about a channel, part of
+ *      the survey response for %NL80211_CMD_GET_SURVEY, nested attribute
+ *      containing info as possible, see &enum survey_info.
+ *
  * @NL80211_ATTR_MAX: highest attribute number currently defined
  * @__NL80211_ATTR_AFTER_LAST: internal use
  */
@@ -718,6 +730,8 @@ enum nl80211_attrs {
 
         NL80211_ATTR_4ADDR,
 
+        NL80211_ATTR_SURVEY_INFO,
+
         /* add attributes here, update the policy in nl80211.c */
 
         __NL80211_ATTR_AFTER_LAST,
@@ -1121,6 +1135,26 @@ enum nl80211_reg_rule_flags {
 };
 
 /**
+ * enum nl80211_survey_info - survey information
+ *
+ * These attribute types are used with %NL80211_ATTR_SURVEY_INFO
+ * when getting information about a survey.
+ *
+ * @__NL80211_SURVEY_INFO_INVALID: attribute number 0 is reserved
+ * @NL80211_SURVEY_INFO_FREQUENCY: center frequency of channel
+ * @NL80211_SURVEY_INFO_NOISE: noise level of channel (u8, dBm)
+ */
+enum nl80211_survey_info {
+        __NL80211_SURVEY_INFO_INVALID,
+        NL80211_SURVEY_INFO_FREQUENCY,
+        NL80211_SURVEY_INFO_NOISE,
+
+        /* keep last */
+        __NL80211_SURVEY_INFO_AFTER_LAST,
+        NL80211_SURVEY_INFO_MAX = __NL80211_SURVEY_INFO_AFTER_LAST - 1
+};
+
+/**
  * enum nl80211_mntr_flags - monitor configuration flags
  *
  * Monitor configuration flags.
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 0e4c51fc63e5..21710fc17eaf 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -235,6 +235,35 @@ struct key_params {
 };
 
 /**
+ * enum survey_info_flags - survey information flags
+ *
+ * Used by the driver to indicate which info in &struct survey_info
+ * it has filled in during the get_survey().
+ */
+enum survey_info_flags {
+        SURVEY_INFO_NOISE_DBM = 1<<0,
+};
+
+/**
+ * struct survey_info - channel survey response
+ *
+ * Used by dump_survey() to report back per-channel survey information.
+ *
+ * @channel: the channel this survey record reports, mandatory
+ * @filled: bitflag of flags from &enum survey_info_flags
+ * @noise: channel noise in dBm. This and all following fields are
+ *     optional
+ *
+ * This structure can later be expanded with things like
+ * channel duty cycle etc.
+ */
+struct survey_info {
+        struct ieee80211_channel *channel;
+        u32 filled;
+        s8 noise;
+};
+
+/**
  * struct beacon_parameters - beacon parameters
  *
  * Used to configure the beacon for an interface.
@@ -944,6 +973,8 @@ struct cfg80211_bitrate_mask {
  * @rfkill_poll: polls the hw rfkill line, use cfg80211 reporting
  *      functions to adjust rfkill hw state
  *
+ * @dump_survey: get site survey information.
+ *
  * @testmode_cmd: run a test mode command
  */
 struct cfg80211_ops {
@@ -1063,6 +1094,9 @@ struct cfg80211_ops {
                                     const u8 *peer,
                                     const struct cfg80211_bitrate_mask *mask);
 
+        int     (*dump_survey)(struct wiphy *wiphy, struct net_device *netdev,
+                        int idx, struct survey_info *info);
+
         /* some temporary stuff to finish wext */
         int     (*set_power_mgmt)(struct wiphy *wiphy, struct net_device *dev,
                                   bool enabled, int timeout);