ath9k: add DFS radar pulse processing

This initial DFS module provides basic functionality to deal
with radar pulses reported by the Atheros DFS HW pulse detector.

The reported data is evaluated and basic plausibility checks
are performed to filter false pulses. Passing radar pulses are
forwarded to pattern detectors which are not yet implemented.

(Some modifications to actually use ATH9K_DFS_DEBUGFS based on comments
from Julian Calaby <julian.calaby@gmail.com>. -- JWL)

Signed-off-by: Zefir Kurtisi <zefir.kurtisi@neratec.com>
Signed-off-by: Luis R. Rodriguez <mcgrof@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 215 insertions, 0 deletions

diff --git a/drivers/net/wireless/ath/ath9k/dfs.c b/drivers/net/wireless/ath/ath9k/dfs.c
new file mode 100644
index 0000000..e4e84a9
--- /dev/null
+++ b/drivers/net/wireless/ath/ath9k/dfs.c
@@ -0,0 +1,215 @@
+/*
+ * Copyright (c) 2008-2011 Atheros Communications Inc.
+ * Copyright (c) 2011 Neratec Solutions AG
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "hw.h"
+#include "hw-ops.h"
+#include "ath9k.h"
+#include "dfs.h"
+#include "dfs_debug.h"
+
+/*
+ * TODO: move into or synchronize this with generic header
+ *	 as soon as IF is defined
+ */
+struct dfs_radar_pulse {
+	u16 freq;
+	u64 ts;
+	u32 width;
+	u8 rssi;
+};
+
+/* internal struct to pass radar data */
+struct ath_radar_data {
+	u8 pulse_bw_info;
+	u8 rssi;
+	u8 ext_rssi;
+	u8 pulse_length_ext;
+	u8 pulse_length_pri;
+};
+
+/* convert pulse duration to usecs, considering clock mode */
+static u32 dur_to_usecs(struct ath_hw *ah, u32 dur)
+{
+	const u32 AR93X_NSECS_PER_DUR = 800;
+	const u32 AR93X_NSECS_PER_DUR_FAST = (8000 / 11);
+	u32 nsecs;
+
+	if (IS_CHAN_A_FAST_CLOCK(ah, ah->curchan))
+		nsecs = dur * AR93X_NSECS_PER_DUR_FAST;
+	else
+		nsecs = dur * AR93X_NSECS_PER_DUR;
+
+	return (nsecs + 500) / 1000;
+}
+
+#define PRI_CH_RADAR_FOUND 0x01
+#define EXT_CH_RADAR_FOUND 0x02
+static bool
+ath9k_postprocess_radar_event(struct ath_softc *sc,
+			      struct ath_radar_data *are,
+			      struct dfs_radar_pulse *drp)
+{
+	u8 rssi;
+	u16 dur;
+
+	ath_dbg(ath9k_hw_common(sc->sc_ah), ATH_DBG_DFS,
+		"pulse_bw_info=0x%x, pri,ext len/rssi=(%u/%u, %u/%u)\n",
+		are->pulse_bw_info,
+		are->pulse_length_pri, are->rssi,
+		are->pulse_length_ext, are->ext_rssi);
+
+	/*
+	 * Only the last 2 bits of the BW info are relevant, they indicate
+	 * which channel the radar was detected in.
+	 */
+	are->pulse_bw_info &= 0x03;
+
+	switch (are->pulse_bw_info) {
+	case PRI_CH_RADAR_FOUND:
+		/* radar in ctrl channel */
+		dur = are->pulse_length_pri;
+		DFS_STAT_INC(sc, pri_phy_errors);
+		/*
+		 * cannot use ctrl channel RSSI
+		 * if extension channel is stronger
+		 */
+		rssi = (are->ext_rssi >= (are->rssi + 3)) ? 0 : are->rssi;
+		break;
+	case EXT_CH_RADAR_FOUND:
+		/* radar in extension channel */
+		dur = are->pulse_length_ext;
+		DFS_STAT_INC(sc, ext_phy_errors);
+		/*
+		 * cannot use extension channel RSSI
+		 * if control channel is stronger
+		 */
+		rssi = (are->rssi >= (are->ext_rssi + 12)) ? 0 : are->ext_rssi;
+		break;
+	case (PRI_CH_RADAR_FOUND | EXT_CH_RADAR_FOUND):
+		/*
+		 * Conducted testing, when pulse is on DC, both pri and ext
+		 * durations are reported to be same
+		 *
+		 * Radiated testing, when pulse is on DC, different pri and
+		 * ext durations are reported, so take the larger of the two
+		 */
+		if (are->pulse_length_ext >= are->pulse_length_pri)
+			dur = are->pulse_length_ext;
+		else
+			dur = are->pulse_length_pri;
+		DFS_STAT_INC(sc, dc_phy_errors);
+
+		/* when both are present use stronger one */
+		rssi = (are->rssi < are->ext_rssi) ? are->ext_rssi : are->rssi;
+		break;
+	default:
+		/*
+		 * Bogus bandwidth info was received in descriptor,
+		 * so ignore this PHY error
+		 */
+		DFS_STAT_INC(sc, bwinfo_discards);
+		return false;
+	}
+
+	if (rssi == 0) {
+		DFS_STAT_INC(sc, rssi_discards);
+		return false;
+	}
+
+	/*
+	 * TODO: check chirping pulses
+	 *	 checks for chirping are dependent on the DFS regulatory domain
+	 *	 used, which is yet TBD
+	 */
+
+	/* convert duration to usecs */
+	drp->width = dur_to_usecs(sc->sc_ah, dur);
+	drp->rssi = rssi;
+
+	DFS_STAT_INC(sc, pulses_detected);
+	return true;
+}
+#undef PRI_CH_RADAR_FOUND
+#undef EXT_CH_RADAR_FOUND
+
+/*
+ * DFS: check PHY-error for radar pulse and feed the detector
+ */
+void ath9k_dfs_process_phyerr(struct ath_softc *sc, void *data,
+			      struct ath_rx_status *rs, u64 mactime)
+{
+	struct ath_radar_data ard;
+	u16 datalen;
+	char *vdata_end;
+	struct dfs_radar_pulse drp;
+	struct ath_hw *ah = sc->sc_ah;
+	struct ath_common *common = ath9k_hw_common(ah);
+
+	if ((!(rs->rs_phyerr != ATH9K_PHYERR_RADAR)) &&
+	    (!(rs->rs_phyerr != ATH9K_PHYERR_FALSE_RADAR_EXT))) {
+		ath_dbg(common, ATH_DBG_DFS,
+			"Error: rs_phyer=0x%x not a radar error\n",
+			rs->rs_phyerr);
+		return;
+	}
+
+	datalen = rs->rs_datalen;
+	if (datalen == 0) {
+		DFS_STAT_INC(sc, datalen_discards);
+		return;
+	}
+
+	ard.rssi = rs->rs_rssi_ctl0;
+	ard.ext_rssi = rs->rs_rssi_ext0;
+
+	/*
+	 * hardware stores this as 8 bit signed value.
+	 * we will cap it at 0 if it is a negative number
+	 */
+	if (ard.rssi & 0x80)
+		ard.rssi = 0;
+	if (ard.ext_rssi & 0x80)
+		ard.ext_rssi = 0;
+
+	vdata_end = (char *)data + datalen;
+	ard.pulse_bw_info = vdata_end[-1];
+	ard.pulse_length_ext = vdata_end[-2];
+	ard.pulse_length_pri = vdata_end[-3];
+
+	ath_dbg(common, ATH_DBG_DFS,
+		"bw_info=%d, length_pri=%d, length_ext=%d, "
+		"rssi_pri=%d, rssi_ext=%d\n",
+		ard.pulse_bw_info, ard.pulse_length_pri, ard.pulse_length_ext,
+		ard.rssi, ard.ext_rssi);
+
+	drp.freq = ah->curchan->channel;
+	drp.ts = mactime;
+	if (ath9k_postprocess_radar_event(sc, &ard, &drp)) {
+		static u64 last_ts;
+		ath_dbg(common, ATH_DBG_DFS,
+			"ath9k_dfs_process_phyerr: channel=%d, ts=%llu, "
+			"width=%d, rssi=%d, delta_ts=%llu\n",
+			drp.freq, drp.ts, drp.width, drp.rssi, drp.ts-last_ts);
+		last_ts = drp.ts;
+		/*
+		 * TODO: forward pulse to pattern detector
+		 *
+		 * ieee80211_add_radar_pulse(drp.freq, drp.ts,
+		 *                           drp.width, drp.rssi);
+		 */
+	}
+}