Allow drivers to indicate their mactime is at RX completion and adjust
for this in mac80211. Based on similar code by Johannes Berg.
Signed-off-by: Thomas Pedersen <thomas@xxxxxxxxxxx>
---
include/net/mac80211.h | 4 ++++
net/mac80211/ibss.c | 29 +++++--------------------
net/mac80211/ieee80211_i.h | 9 ++++++++
net/mac80211/mesh_sync.c | 43 ++++++-------------------------------
net/mac80211/rx.c | 14 ++++++++++---
net/mac80211/util.c | 50 ++++++++++++++++++++++++++++++++++++++++++++
6 files changed, 85 insertions(+), 64 deletions(-)
diff --git a/include/net/mac80211.h b/include/net/mac80211.h
index 00b7204..a2b9b52 100644
--- a/include/net/mac80211.h
+++ b/include/net/mac80211.h
@@ -704,6 +704,9 @@ ieee80211_tx_info_clear_status(struct ieee80211_tx_info *info)
* field) is valid and contains the time the first symbol of the MPDU
* was received. This is useful in monitor mode and for proper IBSS
* merging.
+ * @RX_FLAG_MACTIME_END: The timestamp passed in the RX status (@mactime
+ * field) is valid and contains the time the last symbol of the MPDU
+ * was received.
* @RX_FLAG_SHORTPRE: Short preamble was used for this frame
* @RX_FLAG_HT: HT MCS was used and rate_idx is MCS index
* @RX_FLAG_40MHZ: HT40 (40 MHz) was used
@@ -748,6 +751,7 @@ enum mac80211_rx_flags {
RX_FLAG_AMPDU_IS_LAST = BIT(18),
RX_FLAG_AMPDU_DELIM_CRC_ERROR = BIT(19),
RX_FLAG_AMPDU_DELIM_CRC_KNOWN = BIT(20),
+ RX_FLAG_MACTIME_END = BIT(21),
};
/**
diff --git a/net/mac80211/ibss.c b/net/mac80211/ibss.c
index c7386b2..92500d8 100644
--- a/net/mac80211/ibss.c
+++ b/net/mac80211/ibss.c
@@ -543,30 +543,11 @@ static void ieee80211_rx_bss_info(struct ieee80211_sub_if_data *sdata,
if (ether_addr_equal(cbss->bssid, sdata->u.ibss.bssid))
goto put_bss;
- if (rx_status->flag & RX_FLAG_MACTIME_MPDU) {
- /*
- * For correct IBSS merging we need mactime; since mactime is
- * defined as the time the first data symbol of the frame hits
- * the PHY, and the timestamp of the beacon is defined as "the
- * time that the data symbol containing the first bit of the
- * timestamp is transmitted to the PHY plus the transmitting
- * STA's delays through its local PHY from the MAC-PHY
- * interface to its interface with the WM" (802.11 11.1.2)
- * - equals the time this bit arrives at the receiver - we have
- * to take into account the offset between the two.
- *
- * E.g. at 1 MBit that means mactime is 192 usec earlier
- * (=24 bytes * 8 usecs/byte) than the beacon timestamp.
- */
- int rate;
-
- if (rx_status->flag & RX_FLAG_HT)
- rate = 65; /* TODO: HT rates */
- else
- rate = local->hw.wiphy->bands[band]->
- bitrates[rx_status->rate_idx].bitrate;
-
- rx_timestamp = rx_status->mactime + (24 * 8 * 10 / rate);
+ if (ieee80211_have_rx_timestamp(rx_status)) {
+ /* time when timestamp field was received */
+ rx_timestamp =
+ ieee80211_calculate_rx_timestamp(local, rx_status,
+ len + 4, 24);
} else {
/*
* second best option: get current TSF
diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 3026519..6162342 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1251,7 +1251,16 @@ static inline int ieee80211_bssid_match(const u8 *raddr, const u8 *addr)
is_broadcast_ether_addr(raddr);
}
+static inline bool
+ieee80211_have_rx_timestamp(struct ieee80211_rx_status *status)
+{
+ return status->flag & (RX_FLAG_MACTIME_MPDU | RX_FLAG_MACTIME_END);
+}
+u64 ieee80211_calculate_rx_timestamp(struct ieee80211_local *local,
+ struct ieee80211_rx_status *status,
+ unsigned int mpdu_len,
+ unsigned int mpdu_offset);
int ieee80211_hw_config(struct ieee80211_local *local, u32 changed);
void ieee80211_tx_set_protected(struct ieee80211_tx_data *tx);
void ieee80211_bss_info_change_notify(struct ieee80211_sub_if_data *sdata,
diff --git a/net/mac80211/mesh_sync.c b/net/mac80211/mesh_sync.c
index 407c870..99e792b 100644
--- a/net/mac80211/mesh_sync.c
+++ b/net/mac80211/mesh_sync.c
@@ -116,43 +116,12 @@ static void mesh_sync_offset_rx_bcn_presp(struct ieee80211_sub_if_data *sdata,
goto no_sync;
}
- if (rx_status->flag & RX_FLAG_MACTIME_MPDU && rx_status->mactime) {
- /*
- * The mactime is defined as the time the first data symbol
- * of the frame hits the PHY, and the timestamp of the beacon
- * is defined as "the time that the data symbol containing the
- * first bit of the timestamp is transmitted to the PHY plus
- * the transmitting STA's delays through its local PHY from the
- * MAC-PHY interface to its interface with the WM" (802.11
- * 11.1.2)
- *
- * T_r, in 13.13.2.2.2, is just defined as "the frame reception
- * time" but we unless we interpret that time to be the same
- * time of the beacon timestamp, the offset calculation will be
- * off. Below we adjust t_r to be "the time at which the first
- * symbol of the timestamp element in the beacon is received".
- * This correction depends on the rate.
- *
- * Based on similar code in ibss.c
- */
- int rate;
-
- if (rx_status->flag & RX_FLAG_HT) {
- /* TODO:
- * In principle there could be HT-beacons (Dual Beacon
- * HT Operation options), but for now ignore them and
- * just use the primary (i.e. non-HT) beacons for
- * synchronization.
- * */
- goto no_sync;
- } else
- rate = local->hw.wiphy->bands[rx_status->band]->
- bitrates[rx_status->rate_idx].bitrate;
-
- /* 24 bytes of header * 8 bits/byte *
- * 10*(100 Kbps)/Mbps / rate (100 Kbps)*/
- t_r = rx_status->mactime + (24 * 8 * 10 / rate);
- }
+ if (ieee80211_have_rx_timestamp(rx_status))
+ /* time when timestamp field was received */
+ t_r = ieee80211_calculate_rx_timestamp(local, rx_status,
+ 24 + 12 +
+ elems->total_len + 4,
+ 24);
/* Timing offset calculation (see 13.13.2.2.2) */
t_t = le64_to_cpu(mgmt->u.beacon.timestamp);
diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index 8c1f152..9898fda 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -82,7 +82,7 @@ ieee80211_rx_radiotap_len(struct ieee80211_local *local,
/* always present fields */
len = sizeof(struct ieee80211_radiotap_header) + 9;
- if (status->flag & RX_FLAG_MACTIME_MPDU)
+ if (ieee80211_have_rx_timestamp(status))
len += 8;
if (local->hw.flags & IEEE80211_HW_SIGNAL_DBM)
len += 1;
@@ -118,6 +118,11 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local *local,
struct ieee80211_radiotap_header *rthdr;
unsigned char *pos;
u16 rx_flags = 0;
+ int mpdulen;
+
+ mpdulen = skb->len;
+ if (!(has_fcs && (local->hw.flags & IEEE80211_HW_RX_INCLUDES_FCS)))
+ mpdulen += 4;
rthdr = (struct ieee80211_radiotap_header *)skb_push(skb, rtap_len);
memset(rthdr, 0, rtap_len);
@@ -135,8 +140,11 @@ ieee80211_add_rx_radiotap_header(struct ieee80211_local *local,
/* the order of the following fields is important */
/* IEEE80211_RADIOTAP_TSFT */
- if (status->flag & RX_FLAG_MACTIME_MPDU) {
- put_unaligned_le64(status->mactime, pos);
+ if (ieee80211_have_rx_timestamp(status)) {
+ put_unaligned_le64(
+ ieee80211_calculate_rx_timestamp(local, status,
+ mpdulen, 0),
+ pos);
rthdr->it_present |=
cpu_to_le32(1 << IEEE80211_RADIOTAP_TSFT);
pos += 8;
diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 9556391..9d7271e 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -1990,3 +1990,53 @@ u8 ieee80211_mcs_to_chains(const struct ieee80211_mcs_info *mcs)
return 2;
return 1;
}
+
+/**
+ * ieee80211_calculate_rx_timestamp - calculate timestamp in frame
+ * @status: RX status
+ * @mpdu_len: total MPDU length (including FCS)
+ * @mpdu_offset: offset into MPDU to calculate timestamp at
+ *
+ * This function calculates the RX timestamp at the given MPDU offset, taking
+ * into account what the RX timestamp was. An offset of 0 will just normalize
+ * the timestamp to TSF at beginning of MPDU reception.
+ */
+u64 ieee80211_calculate_rx_timestamp(struct ieee80211_local *local,
+ struct ieee80211_rx_status *status,
+ unsigned int mpdu_len,
+ unsigned int mpdu_offset)
+{
+ u64 ts = status->mactime;
+ struct rate_info ri;
+ u16 rate;
+
+ if (WARN_ON(!ieee80211_have_rx_timestamp(status)))
+ return 0;
+
+ memset(&ri, 0, sizeof(ri));
+
+ /* Fill cfg80211 rate info */
+ if (status->flag & RX_FLAG_HT) {
+ ri.mcs = status->rate_idx;
+ ri.flags |= RATE_INFO_FLAGS_MCS;
+ if (status->flag & RX_FLAG_40MHZ)
+ ri.flags |= RATE_INFO_FLAGS_40_MHZ_WIDTH;
+ if (status->flag & RX_FLAG_SHORT_GI)
+ ri.flags |= RATE_INFO_FLAGS_SHORT_GI;
+ } else {
+ struct ieee80211_supported_band *sband;
+
+ sband = local->hw.wiphy->bands[status->band];
+ ri.legacy = sband->bitrates[status->rate_idx].bitrate;
+ }
+
+ rate = cfg80211_calculate_bitrate(&ri);
+
+ /* rewind from end of MPDU */
+ if (status->flag & RX_FLAG_MACTIME_END)
+ ts -= mpdu_len * 8 * 10 / rate;
+
+ ts += mpdu_offset * 8 * 10 / rate;
+
+ return ts;
+}
--
1.7.10.4
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