Return-path: Received: from mail-pb0-f46.google.com ([209.85.160.46]:45195 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752395Ab2KLSir (ORCPT ); Mon, 12 Nov 2012 13:38:47 -0500 Received: by mail-pb0-f46.google.com with SMTP id rr4so4552697pbb.19 for ; Mon, 12 Nov 2012 10:38:47 -0800 (PST) From: Thomas Pedersen To: johannes@sipsolutions.net Cc: linux-wireless@vger.kernel.org, Thomas Pedersen Subject: [PATCH] mac80211: support RX_FLAG_MACTIME_END Date: Mon, 12 Nov 2012 10:38:33 -0800 Message-Id: <1352745513-1265-1-git-send-email-thomas@cozybit.com> (sfid-20121112_193851_693663_8BFD24CE) Sender: linux-wireless-owner@vger.kernel.org List-ID: 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 --- 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