cfg80211: first stab at channel survey

RFC Superseded Holger Schurig 1 participant 1 message Nov 10, 2009 802.11 (including cfg80211/NL80211)

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Holger Schurig

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2009-11-10 14:20 UTC #0 lore raw

RFC v2 1/1 cfg80211: first stab at channel survey

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 driver to report back channel survey data (e.g. channel noise, channel occupation) back to cfg80211 and thus via nl80211 to user-space.

In future, they will either be a survey-trigger command --- or the existing scan-trigger command will be enhanced. However, the get_survey() operation is usable even in absence of this: a driver can report the channel noise in mBm with the implemented mechanism.

get_survey() is currently modelled like get_key(). I hope that's right.

struct survey_info is modelled like struct station_info. This allows different drivers to fill in different fields.

Signed-off-by Holger Schurig <[email protected]>

---
v2: * channel is mandatory (by way of callback-parameter)
* switched to .dump operation, e.g. nl80211_dump_survey() is now similar to nl80211_dump_stations() and nl80211_send_survey() is similar to nl80211_send_station().
* this also means that the cfg80211_ops dump_survey() now carries an idx. A possible implementation (sketched, not compile-tested) for libertas could be:

int lbs_dump_survey(struct wiphy *wiphy, struct net_device *netdev,
int idx, struct survey_info *info)

{
	struct lbs_private *priv = wiphy_priv(wiphy);

	if (idx != 0)
		return -ENOENT;

	info->channel = priv->channel;
	info->filled = SURVEY_INFO_NOISE_MBM;
	info->noise = CAL_NF(...);
	return 0;
}

but other drives would use idx to iterate over stored survey information and return the according information.

Johannes, this is so far only compile-, sparse- and checkpatch.pl tested. I haven't yet added code to libertas and "iw", but this will be done ASAP.

I also wonder if I should add code to mac80211_hwsim to just report back something, so that we have a hardware independend guinea pig :-)

include/linux/nl80211.h +16 -0

@@ -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 @@
 
 	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 */

@@ -584,6 +592,11 @@
  *	changed then the list changed and the dump should be repeated
  *	completely from scratch.
  *
+ * @NL80211_ATTR_SURVEY_NOISE: noise from survey in mBm
+ * @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
  */

@@ -714,6 +727,9 @@
 
 	NL80211_ATTR_PID,
 
+	NL80211_ATTR_SURVEY_NOISE,
+	NL80211_ATTR_SURVEY_INFO,
+
 	/* add attributes here, update the policy in nl80211.c */
 
 	__NL80211_ATTR_AFTER_LAST,

include/net/cfg80211.h +34 -0

@@ -233,6 +233,35 @@
 };
 
 /**
+ * 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_MBM = 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 mBm. 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;
+	s32 noise;
+};
+
+/**
  * struct beacon_parameters - beacon parameters
  *
  * Used to configure the beacon for an interface.

@@ -941,6 +970,8 @@
  * @rfkill_poll: polls the hw rfkill line, use cfg80211 reporting
  *	functions to adjust rfkill hw state
  *
+ * @dump_survey: get site survey information about.
+ *
  * @testmode_cmd: run a test mode command
  */
 struct cfg80211_ops {

@@ -1060,6 +1091,9 @@
 				    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);

net/wireless/nl80211.c +100 -0

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