mac80211: add helper functions for tracking P2P NoA state

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 140 insertions, 0 deletions

diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index ed93504d24b8..df00f1978a77 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -2594,3 +2594,143 @@ int ieee80211_cs_headroom(struct ieee80211_local *local,
 
         return headroom;
 }
+
+static bool
+ieee80211_extend_noa_desc(struct ieee80211_noa_data *data, u32 tsf, int i)
+{
+        s32 end = data->desc[i].start + data->desc[i].duration - (tsf + 1);
+        int skip;
+
+        if (end > 0)
+                return false;
+
+        /* End time is in the past, check for repetitions */
+        skip = DIV_ROUND_UP(-end, data->desc[i].interval);
+        if (data->count[i] < 255) {
+                if (data->count[i] <= skip) {
+                        data->count[i] = 0;
+                        return false;
+                }
+
+                data->count[i] -= skip;
+        }
+
+        data->desc[i].start += skip * data->desc[i].interval;
+
+        return true;
+}
+
+static bool
+ieee80211_extend_absent_time(struct ieee80211_noa_data *data, u32 tsf,
+                             s32 *offset)
+{
+        bool ret = false;
+        int i;
+
+        for (i = 0; i < IEEE80211_P2P_NOA_DESC_MAX; i++) {
+                s32 cur;
+
+                if (!data->count[i])
+                        continue;
+
+                if (ieee80211_extend_noa_desc(data, tsf + *offset, i))
+                        ret = true;
+
+                cur = data->desc[i].start - tsf;
+                if (cur > *offset)
+                        continue;
+
+                cur = data->desc[i].start + data->desc[i].duration - tsf;
+                if (cur > *offset)
+                        *offset = cur;
+        }
+
+        return ret;
+}
+
+static u32
+ieee80211_get_noa_absent_time(struct ieee80211_noa_data *data, u32 tsf)
+{
+        s32 offset = 0;
+        int tries = 0;
+        /*
+         * arbitrary limit, used to avoid infinite loops when combined NoA
+         * descriptors cover the full time period.
+         */
+        int max_tries = 5;
+
+        ieee80211_extend_absent_time(data, tsf, &offset);
+        do {
+                if (!ieee80211_extend_absent_time(data, tsf, &offset))
+                        break;
+
+                tries++;
+        } while (tries < max_tries);
+
+        return offset;
+}
+
+void ieee80211_update_p2p_noa(struct ieee80211_noa_data *data, u32 tsf)
+{
+        u32 next_offset = BIT(31) - 1;
+        int i;
+
+        data->absent = 0;
+        data->has_next_tsf = false;
+        for (i = 0; i < IEEE80211_P2P_NOA_DESC_MAX; i++) {
+                s32 start;
+
+                if (!data->count[i])
+                        continue;
+
+                ieee80211_extend_noa_desc(data, tsf, i);
+                start = data->desc[i].start - tsf;
+                if (start <= 0)
+                        data->absent |= BIT(i);
+
+                if (next_offset > start)
+                        next_offset = start;
+
+                data->has_next_tsf = true;
+        }
+
+        if (data->absent)
+                next_offset = ieee80211_get_noa_absent_time(data, tsf);
+
+        data->next_tsf = tsf + next_offset;
+}
+EXPORT_SYMBOL(ieee80211_update_p2p_noa);
+
+int ieee80211_parse_p2p_noa(const struct ieee80211_p2p_noa_attr *attr,
+                            struct ieee80211_noa_data *data, u32 tsf)
+{
+        int ret = 0;
+        int i;
+
+        memset(data, 0, sizeof(*data));
+
+        for (i = 0; i < IEEE80211_P2P_NOA_DESC_MAX; i++) {
+                const struct ieee80211_p2p_noa_desc *desc = &attr->desc[i];
+
+                if (!desc->count || !desc->duration)
+                        continue;
+
+                data->count[i] = desc->count;
+                data->desc[i].start = le32_to_cpu(desc->start_time);
+                data->desc[i].duration = le32_to_cpu(desc->duration);
+                data->desc[i].interval = le32_to_cpu(desc->interval);
+
+                if (data->count[i] > 1 &&
+                    data->desc[i].interval < data->desc[i].duration)
+                        continue;
+
+                ieee80211_extend_noa_desc(data, tsf, i);
+                ret++;
+        }
+
+        if (ret)
+                ieee80211_update_p2p_noa(data, tsf);
+
+        return ret;
+}
+EXPORT_SYMBOL(ieee80211_parse_p2p_noa);