From: Johannes Berg <johannes.berg@xxxxxxxxx>
Allow drivers to specify that their mactime
timestamp is at the beginning of the PLCP
and adjust for that in mac80211.
NOTE: This is incomplete, see ieee80211_plcp_duration!!!
Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx>
---
include/net/cfg80211.h | 10 +++++
include/net/mac80211.h | 7 ++++
net/mac80211/ibss.c | 27 +--------------
net/mac80211/ieee80211_i.h | 11 ++++++
net/mac80211/rx.c | 8 ++--
net/mac80211/util.c | 76 +++++++++++++++++++++++++++++++++++++++++++++
net/wireless/core.h | 2 -
net/wireless/util.c | 3 +
8 files changed, 114 insertions(+), 30 deletions(-)
--- wireless-testing.orig/include/net/mac80211.h 2011-02-23 15:03:52.000000000 +0100
+++ wireless-testing/include/net/mac80211.h 2011-02-23 15:05:19.000000000 +0100
@@ -603,10 +603,15 @@ ieee80211_tx_info_clear_status(struct ie
* 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_PLCP: The timestamp passed in the RX status (@mactime
+ * field) is valid and contains the time when the PLCP of the frame
+ * started. mac80211 will automatically correct for the preamble time,
+ * for which the rate and preamble flags etc. MUST be set correctly.
* @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
* @RX_FLAG_SHORT_GI: Short guard interval was used
+ * @RX_FLAG_HT_GF: This frame was received in a HT-greenfield transmission
*/
enum mac80211_rx_flags {
RX_FLAG_MMIC_ERROR = 1<<0,
@@ -620,6 +625,8 @@ enum mac80211_rx_flags {
RX_FLAG_HT = 1<<9,
RX_FLAG_40MHZ = 1<<10,
RX_FLAG_SHORT_GI = 1<<11,
+ RX_FLAG_MACTIME_PLCP = 1<<12,
+ RX_FLAG_HT_GF = 1<<13,
};
/**
--- wireless-testing.orig/include/net/cfg80211.h 2011-02-23 15:03:52.000000000 +0100
+++ wireless-testing/include/net/cfg80211.h 2011-02-23 15:05:19.000000000 +0100
@@ -471,6 +471,16 @@ struct rate_info {
};
/**
+ * cfg80211_calculate_bitrate - calculate bitrate in 100kbit/s
+ * @rate: The rate information
+ *
+ * Calculates the net bitrate in units of 100kbit/s from the
+ * given rate/MCS information.
+ */
+u16 cfg80211_calculate_bitrate(struct rate_info *rate);
+
+
+/**
* struct station_info - station information
*
* Station information filled by driver for get_station() and dump_station.
--- wireless-testing.orig/net/mac80211/ieee80211_i.h 2011-02-23 15:03:52.000000000 +0100
+++ wireless-testing/net/mac80211/ieee80211_i.h 2011-02-23 15:05:19.000000000 +0100
@@ -1347,6 +1347,17 @@ size_t ieee80211_ie_split(const u8 *ies,
const u8 *ids, int n_ids, size_t offset);
size_t ieee80211_ie_split_vendor(const u8 *ies, size_t ielen, size_t offset);
+u64 ieee80211_calculate_rx_timestamp(struct ieee80211_local *local,
+ struct ieee80211_rx_status *status,
+ unsigned int mpdu_offset);
+
+static inline bool
+ieee80211_have_rx_timestamp(struct ieee80211_rx_status *status)
+{
+ return status->rx_flags & (RX_FLAG_MACTIME_MPDU | RX_FLAG_MACTIME_PLCP);
+}
+
+
/* internal work items */
void ieee80211_work_init(struct ieee80211_local *local);
void ieee80211_add_work(struct ieee80211_work *wk);
--- wireless-testing.orig/net/mac80211/util.c 2011-02-23 15:03:52.000000000 +0100
+++ wireless-testing/net/mac80211/util.c 2011-02-23 15:08:06.000000000 +0100
@@ -1418,3 +1418,79 @@ size_t ieee80211_ie_split_vendor(const u
return pos;
}
+
+static u64 ieee80211_plcp_duration(struct ieee80211_rx_status *status)
+{
+ if (status->rx_flags & RX_FLAG_HT_GF) {
+ /* HT-greenfield preamble */
+ /* TODO */
+ return 0;
+ } else if (status->rx_flags & RX_FLAG_HT) {
+ /* HT-mixed preamble */
+ /* TODO */
+ return 0;
+ } else switch (status->band) {
+ case IEEE80211_BAND_2GHZ:
+ if (status->rx_flags & RX_FLAG_SHORTPRE)
+ return 96;
+ return 192;
+ case IEEE80211_BAND_5GHZ:
+ /* This appears to be correct for iwlwifi, but is it really? */
+ return 16;
+ case IEEE80211_NUM_BANDS:
+ break;
+ }
+
+ WARN_ON_ONCE(1);
+ return 0;
+}
+
+/**
+ * ieee80211_calculate_rx_timestamp - calculate timestamp in frame
+ * @status: RX status
+ * @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.
+ */
+u64 ieee80211_calculate_rx_timestamp(struct ieee80211_local *local,
+ struct ieee80211_rx_status *status,
+ unsigned int mpdu_offset)
+{
+ u64 ts = status->mactime;
+ struct rate_info ri;
+ u16 rate;
+
+ if (WARN_ON(!ieee80211_have_rx_timestamp(status)))
+ return 0;
+
+ /* Adjust for PLCP header */
+ if (status->rx_flags & RX_FLAG_MACTIME_PLCP)
+ ts += ieee80211_plcp_duration(status);
+
+ if (mpdu_offset == 0)
+ return ts;
+
+ memset(&ri, 0, sizeof(ri));
+
+ /* Fill cfg80211 rate info */
+ if (status->rx_flags & RX_FLAG_HT) {
+ ri.mcs = status->rate_idx;
+ ri.flags |= RATE_INFO_FLAGS_MCS;
+ if (status->rx_flags & RX_FLAG_40MHZ)
+ ri.flags |= RATE_INFO_FLAGS_40_MHZ_WIDTH;
+ if (status->rx_flags & 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);
+
+ ts += mpdu_offset * 8 * 10 / rate;
+
+ return ts;
+}
--- wireless-testing.orig/net/wireless/core.h 2011-02-23 15:03:52.000000000 +0100
+++ wireless-testing/net/wireless/core.h 2011-02-23 15:05:19.000000000 +0100
@@ -410,8 +410,6 @@ int cfg80211_set_freq(struct cfg80211_re
struct wireless_dev *wdev, int freq,
enum nl80211_channel_type channel_type);
-u16 cfg80211_calculate_bitrate(struct rate_info *rate);
-
#ifdef CONFIG_CFG80211_DEVELOPER_WARNINGS
#define CFG80211_DEV_WARN_ON(cond) WARN_ON(cond)
#else
--- wireless-testing.orig/net/wireless/util.c 2011-02-23 15:03:52.000000000 +0100
+++ wireless-testing/net/wireless/util.c 2011-02-23 15:05:19.000000000 +0100
@@ -872,7 +872,7 @@ u16 cfg80211_calculate_bitrate(struct ra
return rate->legacy;
/* the formula below does only work for MCS values smaller than 32 */
- if (rate->mcs >= 32)
+ if (WARN_ON_ONCE(rate->mcs >= 32))
return 0;
modulation = rate->mcs & 7;
@@ -896,3 +896,4 @@ u16 cfg80211_calculate_bitrate(struct ra
/* do NOT round down here */
return (bitrate + 50000) / 100000;
}
+EXPORT_SYMBOL(cfg80211_calculate_bitrate);
--- wireless-testing.orig/net/mac80211/ibss.c 2011-02-23 15:03:53.000000000 +0100
+++ wireless-testing/net/mac80211/ibss.c 2011-02-23 15:05:19.000000000 +0100
@@ -354,30 +354,9 @@ static void ieee80211_rx_bss_info(struct
if (memcmp(cbss->bssid, sdata->u.ibss.bssid, ETH_ALEN) == 0)
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)) {
+ rx_timestamp =
+ ieee80211_calculate_rx_timestamp(local, rx_status, 24);
} else {
/*
* second best option: get current TSF
--- wireless-testing.orig/net/mac80211/rx.c 2011-02-23 15:03:52.000000000 +0100
+++ wireless-testing/net/mac80211/rx.c 2011-02-23 15:05:19.000000000 +0100
@@ -77,7 +77,7 @@ ieee80211_rx_radiotap_len(struct ieee802
/* 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;
@@ -123,8 +123,10 @@ ieee80211_add_rx_radiotap_header(struct
/* 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, 0),
+ pos);
rthdr->it_present |=
cpu_to_le32(1 << IEEE80211_RADIOTAP_TSFT);
pos += 8;
--
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