[RFC] cfg80211: survey report capability

[Holger Schurig <holgerschurig@googlemail.com>]

[RFC] 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 <holgerschurig@gmail.com>

--- linux-wl.orig/include/linux/nl80211.h
+++ linux-wl/include/linux/nl80211.h
@@ -159,6 +159,8 @@
  *	NL80211_CMD_GET_SCAN and on the "scan" multicast group)
  * @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_REG_CHANGE: indicates to userspace the regulatory domain
  * 	has been changed and provides details of the request information
@@ -341,6 +343,8 @@
 
 	NL80211_CMD_SET_WIPHY_NETNS,
 
+	NL80211_CMD_GET_SURVEY,
+
 	/* add new commands above here */
 
 	/* used to define NL80211_CMD_MAX below */
@@ -584,6 +588,8 @@
  *	changed then the list changed and the dump should be repeated
  *	completely from scratch.
  *
+ * @NL80211_CHANNEL_NOISE: Noise on channel in mBm
+ *
  * @NL80211_ATTR_MAX: highest attribute number currently defined
  * @__NL80211_ATTR_AFTER_LAST: internal use
  */
@@ -714,6 +720,8 @@
 
 	NL80211_ATTR_PID,
 
+	NL80211_ATTR_NOISE,
+
 	/* add attributes here, update the policy in nl80211.c */
 
 	__NL80211_ATTR_AFTER_LAST,
--- linux-wl.orig/include/net/cfg80211.h
+++ linux-wl/include/net/cfg80211.h
@@ -232,6 +232,35 @@
 	u32 cipher;
 };
 
+/** 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_CHANNEL = 1<<0,
+	SURVEY_INFO_NOISE = 1<<1,
+};
+
+/**
+ * struct survey_info - channel survey response
+ *
+ * Used from the get_survey() callback to report back
+ * per-channel survey information.
+ *
+ * @filled: bitflag of flags from &enum survey_info_flags
+ * @noise: channel noise in mBm
+ * @channel: the channel this survey record reports
+ *
+ * This structure can later be expanded with things like
+ * channel duty cycles etc.
+ */
+struct survey_info {
+	u32 filled;
+	struct ieee80211_channel *channel;
+	s8 noise;
+};
+
 /**
  * struct beacon_parameters - beacon parameters
  *
@@ -941,6 +970,8 @@
  * @rfkill_poll: polls the hw rfkill line, use cfg80211 reporting
  *	functions to adjust rfkill hw state
  *
+ * @get_survey: get site survey information about.
+ *
  * @testmode_cmd: run a test mode command
  */
 struct cfg80211_ops {
@@ -1060,6 +1091,10 @@
 				    const u8 *peer,
 				    const struct cfg80211_bitrate_mask *mask);
 
+	int	(*get_survey)(struct wiphy *wiphy, struct net_device *netdev,
+			void *cookie,
+			void (*callback)(void *cookie, struct survey_info*));
+
 	/* some temporary stuff to finish wext */
 	int	(*set_power_mgmt)(struct wiphy *wiphy, struct net_device *dev,
 				  bool enabled, int timeout);
--- linux-wl.orig/net/wireless/nl80211.c
+++ linux-wl/net/wireless/nl80211.c
@@ -3238,6 +3238,155 @@
 	return err;
 }
 
+struct get_survey_cookie {
+	struct sk_buff *msg;
+	int error;
+};
+
+static void get_survey_callback(void *c, struct survey_info *params)
+{
+	struct get_survey_cookie *cookie = c;
+
+	if (params->filled & SURVEY_INFO_CHANNEL)
+		if (nl80211_msg_put_channel(cookie->msg, params->channel))
+			goto nla_put_failure;
+
+	if (params->filled & SURVEY_INFO_NOISE)
+		NLA_PUT_U32(cookie->msg, NL80211_ATTR_NOISE,
+			params->noise);
+
+ nla_put_failure:
+	cookie->error = 1;
+}
+
+static int nl80211_get_survey(struct sk_buff *skb, struct genl_info *info)
+{
+	struct cfg80211_registered_device *rdev;
+	struct net_device *dev;
+	struct get_key_cookie cookie = {
+		.error = 0,
+	};
+	int err;
+	void *hdr;
+	struct sk_buff *msg;
+
+	rtnl_lock();
+
+	err = get_rdev_dev_by_info_ifindex(info, &rdev, &dev);
+	if (err)
+		goto unlock_rtnl;
+
+	if (!rdev->ops->get_survey) {
+		err = -EOPNOTSUPP;
+		goto out;
+	}
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	hdr = nl80211hdr_put(msg, info->snd_pid, info->snd_seq, 0,
+			     NL80211_CMD_NEW_KEY);
+
+	if (IS_ERR(hdr)) {
+		err = PTR_ERR(hdr);
+		goto free_msg;
+	}
+
+	cookie.msg = msg;
+
+	NLA_PUT_U32(msg, NL80211_ATTR_IFINDEX, dev->ifindex);
+
+	err = rdev->ops->get_survey(&rdev->wiphy, dev, &cookie,
+				    get_survey_callback);
+
+	if (err)
+		goto free_msg;
+
+	if (cookie.error)
+		goto nla_put_failure;
+
+	genlmsg_end(msg, hdr);
+	err = genlmsg_reply(msg, info);
+	goto out;
+
+ nla_put_failure:
+	err = -ENOBUFS;
+ free_msg:
+	nlmsg_free(msg);
+ out:
+	cfg80211_unlock_rdev(rdev);
+	dev_put(dev);
+ unlock_rtnl:
+	rtnl_unlock();
+
+	return err;
+
+/*
+	if (!ifidx) {
+		err = nlmsg_parse(cb->nlh, GENL_HDRLEN + nl80211_fam.hdrsize,
+				  nl80211_fam.attrbuf, nl80211_fam.maxattr,
+				  nl80211_policy);
+		if (err)
+			return err;
+
+		if (!nl80211_fam.attrbuf[NL80211_ATTR_IFINDEX])
+			return -EINVAL;
+
+		ifidx = nla_get_u32(nl80211_fam.attrbuf[NL80211_ATTR_IFINDEX]);
+		if (!ifidx)
+			return -EINVAL;
+		cb->args[0] = ifidx;
+	}
+
+	dev = dev_get_by_index(sock_net(skb->sk), ifidx);
+	if (!dev)
+		return -ENODEV;
+
+	rdev = cfg80211_get_dev_from_ifindex(sock_net(skb->sk), ifidx);
+	if (IS_ERR(rdev)) {
+		err = PTR_ERR(rdev);
+		goto out_put_netdev;
+	}
+
+	wdev = dev->ieee80211_ptr;
+
+	wdev_lock(wdev);
+	//TODO
+
+	void *hdr;
+	int i;
+
+	ASSERT_WDEV_LOCK(wdev);
+
+	hdr = nl80211hdr_put(msg, pid, seq, flags,
+			     NL80211_CMD_NEW_SCAN_RESULTS);
+	if (!hdr)
+		return -1;
+
+
+	return genlmsg_end(msg, hdr);
+
+ nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+	return -EMSGSIZE;
+
+
+	//TODO
+	wdev_unlock(wdev);
+
+	cb->args[1] = idx;
+	err = skb->len;
+	cfg80211_unlock_rdev(rdev);
+ out_put_netdev:
+	dev_put(dev);
+
+	return err;
+*/
+}
+
 static bool nl80211_valid_auth_type(enum nl80211_auth_type auth_type)
 {
 	return auth_type <= NL80211_AUTHTYPE_MAX;
@@ -4315,6 +4464,11 @@
 		.policy = nl80211_policy,
 		.flags = GENL_ADMIN_PERM,
 	},
+	{
+		.cmd = NL80211_CMD_GET_SURVEY,
+		.doit = nl80211_get_survey,
+		.policy = nl80211_policy,
+	},
 };
 static struct genl_multicast_group nl80211_mlme_mcgrp = {
 	.name = "mlme",


--
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