211 lines
6.4 KiB
Diff
211 lines
6.4 KiB
Diff
From: Zefir Kurtisi <zefir.kurtisi@neratec.com>
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Date: Tue, 16 Jun 2015 12:52:16 +0200
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Subject: [PATCH] ath9k: DFS - add pulse chirp detection for FCC
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FCC long pulse radar (type 5) requires pulses to be
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checked for chirping. This patch implements chirp
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detection based on the FFT data provided for long
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pulses.
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A chirp is detected when a set of criteria defined
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by FCC pulse characteristics is met, including
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* have at least 4 FFT samples
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* max_bin index moves equidistantly between samples
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* the gradient is within defined range
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The chirp detection has been tested with reference
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radar generating devices and proved to work reliably.
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Signed-off-by: Zefir Kurtisi <zefir.kurtisi@neratec.com>
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---
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--- a/drivers/net/wireless/ath/ath9k/dfs.c
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+++ b/drivers/net/wireless/ath/ath9k/dfs.c
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@@ -30,6 +30,157 @@ struct ath_radar_data {
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u8 pulse_length_pri;
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};
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+/**** begin: CHIRP ************************************************************/
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+
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+/* min and max gradients for defined FCC chirping pulses, given by
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+ * - 20MHz chirp width over a pulse width of 50us
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+ * - 5MHz chirp width over a pulse width of 100us
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+ */
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+static const int BIN_DELTA_MIN = 1;
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+static const int BIN_DELTA_MAX = 10;
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+
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+/* we need at least 3 deltas / 4 samples for a reliable chirp detection */
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+#define NUM_DIFFS 3
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+static const int FFT_NUM_SAMPLES = (NUM_DIFFS + 1);
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+
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+/* Threshold for difference of delta peaks */
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+static const int MAX_DIFF = 2;
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+
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+/* width range to be checked for chirping */
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+static const int MIN_CHIRP_PULSE_WIDTH = 20;
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+static const int MAX_CHIRP_PULSE_WIDTH = 110;
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+
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+struct ath9k_dfs_fft_20 {
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+ u8 bin[28];
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+ u8 lower_bins[3];
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+} __packed;
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+struct ath9k_dfs_fft_40 {
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+ u8 bin[64];
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+ u8 lower_bins[3];
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+ u8 upper_bins[3];
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+} __packed;
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+
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+static inline int fft_max_index(u8 *bins)
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+{
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+ return (bins[2] & 0xfc) >> 2;
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+}
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+static inline int fft_max_magnitude(u8 *bins)
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+{
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+ return (bins[0] & 0xc0) >> 6 | bins[1] << 2 | (bins[2] & 0x03) << 10;
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+}
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+static inline u8 fft_bitmap_weight(u8 *bins)
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+{
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+ return bins[0] & 0x3f;
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+}
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+
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+static int ath9k_get_max_index_ht40(struct ath9k_dfs_fft_40 *fft,
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+ bool is_ctl, bool is_ext)
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+{
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+ const int DFS_UPPER_BIN_OFFSET = 64;
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+ /* if detected radar on both channels, select the significant one */
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+ if (is_ctl && is_ext) {
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+ /* first check wether channels have 'strong' bins */
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+ is_ctl = fft_bitmap_weight(fft->lower_bins) != 0;
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+ is_ext = fft_bitmap_weight(fft->upper_bins) != 0;
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+
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+ /* if still unclear, take higher magnitude */
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+ if (is_ctl && is_ext) {
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+ int mag_lower = fft_max_magnitude(fft->lower_bins);
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+ int mag_upper = fft_max_magnitude(fft->upper_bins);
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+ if (mag_upper > mag_lower)
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+ is_ctl = false;
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+ else
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+ is_ext = false;
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+ }
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+ }
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+ if (is_ctl)
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+ return fft_max_index(fft->lower_bins);
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+ return fft_max_index(fft->upper_bins) + DFS_UPPER_BIN_OFFSET;
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+}
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+static bool ath9k_check_chirping(struct ath_softc *sc, u8 *data,
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+ int datalen, bool is_ctl, bool is_ext)
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+{
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+ int i;
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+ int max_bin[FFT_NUM_SAMPLES];
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+ struct ath_hw *ah = sc->sc_ah;
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+ struct ath_common *common = ath9k_hw_common(ah);
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+ int prev_delta;
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+
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+ if (IS_CHAN_HT40(ah->curchan)) {
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+ struct ath9k_dfs_fft_40 *fft = (struct ath9k_dfs_fft_40 *) data;
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+ int num_fft_packets = datalen / sizeof(*fft);
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+ if (num_fft_packets == 0)
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+ return false;
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+
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+ ath_dbg(common, DFS, "HT40: datalen=%d, num_fft_packets=%d\n",
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+ datalen, num_fft_packets);
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+ if (num_fft_packets < (FFT_NUM_SAMPLES)) {
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+ ath_dbg(common, DFS, "not enough packets for chirp\n");
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+ return false;
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+ }
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+ /* HW sometimes adds 2 garbage bytes in front of FFT samples */
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+ if ((datalen % sizeof(*fft)) == 2) {
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+ fft = (struct ath9k_dfs_fft_40 *) (data + 2);
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+ ath_dbg(common, DFS, "fixing datalen by 2\n");
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+ }
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+ if (IS_CHAN_HT40MINUS(ah->curchan)) {
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+ int temp = is_ctl;
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+ is_ctl = is_ext;
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+ is_ext = temp;
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+ }
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+ for (i = 0; i < FFT_NUM_SAMPLES; i++)
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+ max_bin[i] = ath9k_get_max_index_ht40(fft + i, is_ctl,
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+ is_ext);
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+ } else {
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+ struct ath9k_dfs_fft_20 *fft = (struct ath9k_dfs_fft_20 *) data;
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+ int num_fft_packets = datalen / sizeof(*fft);
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+ if (num_fft_packets == 0)
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+ return false;
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+ ath_dbg(common, DFS, "HT20: datalen=%d, num_fft_packets=%d\n",
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+ datalen, num_fft_packets);
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+ if (num_fft_packets < (FFT_NUM_SAMPLES)) {
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+ ath_dbg(common, DFS, "not enough packets for chirp\n");
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+ return false;
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+ }
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+ /* in ht20, this is a 6-bit signed number => shift it to 0 */
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+ for (i = 0; i < FFT_NUM_SAMPLES; i++)
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+ max_bin[i] = fft_max_index(fft[i].lower_bins) ^ 0x20;
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+ }
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+ ath_dbg(common, DFS, "bin_max = [%d, %d, %d, %d]\n",
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+ max_bin[0], max_bin[1], max_bin[2], max_bin[3]);
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+
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+ /* Check for chirp attributes within specs
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+ * a) delta of adjacent max_bins is within range
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+ * b) delta of adjacent deltas are within tolerance
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+ */
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+ prev_delta = 0;
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+ for (i = 0; i < NUM_DIFFS; i++) {
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+ int ddelta = -1;
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+ int delta = max_bin[i + 1] - max_bin[i];
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+
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+ /* ensure gradient is within valid range */
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+ if (abs(delta) < BIN_DELTA_MIN || abs(delta) > BIN_DELTA_MAX) {
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+ ath_dbg(common, DFS, "CHIRP: invalid delta %d "
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+ "in sample %d\n", delta, i);
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+ return false;
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+ }
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+ if (i == 0)
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+ goto done;
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+ ddelta = delta - prev_delta;
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+ if (abs(ddelta) > MAX_DIFF) {
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+ ath_dbg(common, DFS, "CHIRP: ddelta %d too high\n",
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+ ddelta);
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+ return false;
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+ }
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+done:
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+ ath_dbg(common, DFS, "CHIRP - %d: delta=%d, ddelta=%d\n",
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+ i, delta, ddelta);
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+ prev_delta = delta;
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+ }
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+ return true;
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+}
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+/**** end: CHIRP **************************************************************/
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+
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/* convert pulse duration to usecs, considering clock mode */
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static u32 dur_to_usecs(struct ath_hw *ah, u32 dur)
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{
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@@ -113,12 +264,6 @@ ath9k_postprocess_radar_event(struct ath
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return false;
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}
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- /*
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- * TODO: check chirping pulses
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- * checks for chirping are dependent on the DFS regulatory domain
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- * used, which is yet TBD
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- */
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-
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/* convert duration to usecs */
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pe->width = dur_to_usecs(sc->sc_ah, dur);
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pe->rssi = rssi;
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@@ -190,6 +335,16 @@ void ath9k_dfs_process_phyerr(struct ath
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if (!ath9k_postprocess_radar_event(sc, &ard, &pe))
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return;
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+ if (pe.width > MIN_CHIRP_PULSE_WIDTH &&
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+ pe.width < MAX_CHIRP_PULSE_WIDTH) {
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+ bool is_ctl = !!(ard.pulse_bw_info & PRI_CH_RADAR_FOUND);
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+ bool is_ext = !!(ard.pulse_bw_info & EXT_CH_RADAR_FOUND);
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+ int clen = datalen - 3;
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+ pe.chirp = ath9k_check_chirping(sc, data, clen, is_ctl, is_ext);
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+ } else {
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+ pe.chirp = false;
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+ }
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+
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ath_dbg(common, DFS,
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"ath9k_dfs_process_phyerr: type=%d, freq=%d, ts=%llu, "
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"width=%d, rssi=%d, delta_ts=%llu\n",
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