cfg80211: introduce critical protocol indication from user-space

Some protocols need a more reliable connection to complete
successful in reasonable time. This patch adds a user-space
API to indicate the wireless driver that a critical protocol
is about to commence and when it is done, using nl80211 primitives
NL80211_CMD_CRIT_PROTOCOL_START and NL80211_CRIT_PROTOCOL_STOP.

There can be only on critical protocol session started per
registered cfg80211 device.

The driver can support this by implementing the cfg80211 callbacks
.crit_proto_start() and .crit_proto_stop(). Examples of protocols
that can benefit from this are DHCP, EAPOL, APIPA. Exactly how the
link can/should be made more reliable is up to the driver. Things
to consider are avoid scanning, no multi-channel operations, and
alter coexistence schemes.

Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Franky (Zhenhui) Lin <frankyl@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

2 files changed, 62 insertions, 0 deletions

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index dff96d8cafcd..26b5b692c22b 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -2002,6 +2002,12 @@ struct cfg80211_update_ft_ies_params {
  * @update_ft_ies: Provide updated Fast BSS Transition information to the
  *      driver. If the SME is in the driver/firmware, this information can be
  *      used in building Authentication and Reassociation Request frames.
+ *
+ * @crit_proto_start: Indicates a critical protocol needs more link reliability
+ *      for a given duration (milliseconds). The protocol is provided so the
+ *      driver can take the most appropriate actions.
+ * @crit_proto_stop: Indicates critical protocol no longer needs increased link
+ *      reliability. This operation can not fail.
  */
 struct cfg80211_ops {
         int     (*suspend)(struct wiphy *wiphy, struct cfg80211_wowlan *wow);
@@ -2231,6 +2237,12 @@ struct cfg80211_ops {
                                          struct cfg80211_chan_def *chandef);
         int     (*update_ft_ies)(struct wiphy *wiphy, struct net_device *dev,
                                  struct cfg80211_update_ft_ies_params *ftie);
+        int     (*crit_proto_start)(struct wiphy *wiphy,
+                                    struct wireless_dev *wdev,
+                                    enum nl80211_crit_proto_id protocol,
+                                    u16 duration);
+        void    (*crit_proto_stop)(struct wiphy *wiphy,
+                                   struct wireless_dev *wdev);
 };
 
 /*
@@ -4137,6 +4149,17 @@ void cfg80211_report_wowlan_wakeup(struct wireless_dev *wdev,
                                    struct cfg80211_wowlan_wakeup *wakeup,
                                    gfp_t gfp);
 
+/**
+ * cfg80211_crit_proto_stopped() - indicate critical protocol stopped by driver.
+ *
+ * @wdev: the wireless device for which critical protocol is stopped.
+ *
+ * This function can be called by the driver to indicate it has reverted
+ * operation back to normal. One reason could be that the duration given
+ * by .crit_proto_start() has expired.
+ */
+void cfg80211_crit_proto_stopped(struct wireless_dev *wdev, gfp_t gfp);
+
 /* Logging, debugging and troubleshooting/diagnostic helpers. */
 
 /* wiphy_printk helpers, similar to dev_printk */
diff --git a/include/uapi/linux/nl80211.h b/include/uapi/linux/nl80211.h
index 79da8710448e..d1e48b5e348f 100644
--- a/include/uapi/linux/nl80211.h
+++ b/include/uapi/linux/nl80211.h
@@ -639,6 +639,13 @@
  *      with the relevant Information Elements. This event is used to report
  *      received FT IEs (MDIE, FTIE, RSN IE, TIE, RICIE).
  *
+ * @NL80211_CMD_CRIT_PROTOCOL_START: Indicates user-space will start running
+ *      a critical protocol that needs more reliability in the connection to
+ *      complete.
+ *
+ * @NL80211_CMD_CRIT_PROTOCOL_STOP: Indicates the connection reliability can
+ *      return back to normal.
+ *
  * @NL80211_CMD_MAX: highest used command number
  * @__NL80211_CMD_AFTER_LAST: internal use
  */
@@ -798,6 +805,9 @@ enum nl80211_commands {
         NL80211_CMD_UPDATE_FT_IES,
         NL80211_CMD_FT_EVENT,
 
+        NL80211_CMD_CRIT_PROTOCOL_START,
+        NL80211_CMD_CRIT_PROTOCOL_STOP,
+
         /* add new commands above here */
 
         /* used to define NL80211_CMD_MAX below */
@@ -1414,6 +1424,11 @@ enum nl80211_commands {
  * @NL80211_ATTR_IE_RIC: Resource Information Container Information
  *      Element
  *
+ * @NL80211_ATTR_CRIT_PROT_ID: critical protocol identifier requiring increased
+ *      reliability, see &enum nl80211_crit_proto_id (u16).
+ * @NL80211_ATTR_MAX_CRIT_PROT_DURATION: duration in milliseconds in which
+ *      the connection should have increased reliability (u16).
+ *
  * @NL80211_ATTR_MAX: highest attribute number currently defined
  * @__NL80211_ATTR_AFTER_LAST: internal use
  */
@@ -1709,6 +1724,9 @@ enum nl80211_attrs {
         NL80211_ATTR_MDID,
         NL80211_ATTR_IE_RIC,
 
+        NL80211_ATTR_CRIT_PROT_ID,
+        NL80211_ATTR_MAX_CRIT_PROT_DURATION,
+
         /* add attributes here, update the policy in nl80211.c */
 
         __NL80211_ATTR_AFTER_LAST,
@@ -3682,4 +3700,25 @@ enum nl80211_protocol_features {
         NL80211_PROTOCOL_FEATURE_SPLIT_WIPHY_DUMP =     1 << 0,
 };
 
+/**
+ * enum nl80211_crit_proto_id - nl80211 critical protocol identifiers
+ *
+ * @NL80211_CRIT_PROTO_UNSPEC: protocol unspecified.
+ * @NL80211_CRIT_PROTO_DHCP: BOOTP or DHCPv6 protocol.
+ * @NL80211_CRIT_PROTO_EAPOL: EAPOL protocol.
+ * @NL80211_CRIT_PROTO_APIPA: APIPA protocol.
+ * @NUM_NL80211_CRIT_PROTO: must be kept last.
+ */
+enum nl80211_crit_proto_id {
+        NL80211_CRIT_PROTO_UNSPEC,
+        NL80211_CRIT_PROTO_DHCP,
+        NL80211_CRIT_PROTO_EAPOL,
+        NL80211_CRIT_PROTO_APIPA,
+        /* add other protocols before this one */
+        NUM_NL80211_CRIT_PROTO
+};
+
+/* maximum duration for critical protocol measures */
+#define NL80211_CRIT_PROTO_MAX_DURATION         5000 /* msec */
+
 #endif /* __LINUX_NL80211_H */