*
* Redistribution and use in source and binary forms are permitted
* provided that the following conditions are met:
- * 1. The materials contained herein are unmodified and are used
- * unmodified.
- * 2. Redistributions of source code must retain the above copyright
+ * 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following NO
* ''WARRANTY'' disclaimer below (''Disclaimer''), without
* modification.
- * 3. Redistributions in binary form must reproduce at minimum a
+ * 2. Redistributions in binary form must reproduce at minimum a
* disclaimer similar to the Disclaimer below and any redistribution
* must be conditioned upon including a substantially similar
* Disclaimer requirement for further binary redistribution.
- * 4. Neither the names of the above-listed copyright holders nor the
+ * 3. Neither the names of the above-listed copyright holders nor the
* names of any contributors may be used to endorse or promote
* product derived from this software without specific prior written
* permission.
/* TSF Handling */
/****************/
+#define ATH9K_HTC_MAX_TSF_READ 3
+
u_int64_t ar5416GetTsf64(struct ath_hal *ah)
{
- u_int64_t tsf;
-
- tsf = ioread32_mac(AR_TSF_U32);
- tsf = (tsf << 32) | ioread32_mac(AR_TSF_L32);
+ a_uint32_t tsf_lower, tsf_upper1, tsf_upper2;
+ a_int32_t i;
+
+ tsf_upper1 = ioread32_mac(AR_TSF_U32);
+ for (i = 0; i < ATH9K_HTC_MAX_TSF_READ; i++) {
+ tsf_lower = ioread32_mac(AR_TSF_L32);
+ tsf_upper2 = ioread32_mac(AR_TSF_U32);
+ if (tsf_upper2 == tsf_upper1)
+ break;
+ tsf_upper1 = tsf_upper2;
+ }
- return tsf;
+ return (((u_int64_t)tsf_upper2 << 32) | tsf_lower);
}
/******/
void ath_tgt_tx_sched_nonaggr(struct ath_softc_tgt *sc,struct ath_buf * bf_host);
/*
- * Extend a 32 bit TSF to 64 bit, taking wrapping into account.
+ * Extend a 32 bit TSF to nearest 64 bit TSF value.
+ * When the adapter is a STATION, its local TSF is periodically modified by
+ * the hardware to match the BSS TSF (as received in beacon packets), and
+ * rstamp may appear to be from the future or from the past (with reference
+ * to the current local TSF) because of jitter. This is mostly noticable in
+ * highly congested channels. The code uses signed modulo arithmetic to
+ * handle both past/future cases and signed-extension to avoid branches.
+ * Test cases:
+ * extend(0x0000001200000004, 0x00000006) == 0x0000001200000006
+ * extend(0x0000001200000004, 0x00000002) == 0x0000001200000002
+ * extend(0x0000001200000004, 0xfffffffe) == 0x00000011fffffffe ! tsfhigh--
+ * extend(0x000000127ffffffe, 0x80000002) == 0x0000001280000002
+ * extend(0x0000001280000002, 0x7ffffffe) == 0x000000127ffffffe
+ * extend(0x00000012fffffffc, 0xfffffffe) == 0x00000012fffffffe
+ * extend(0x00000012fffffffc, 0xfffffffa) == 0x00000012fffffffa
+ * extend(0x00000012fffffffc, 0x00000002) == 0x0000001300000002 ! tsfhigh++
*/
static u_int64_t ath_extend_tsf(struct ath_softc_tgt *sc, u_int32_t rstamp)
{
struct ath_hal *ah = sc->sc_ah;
u_int64_t tsf;
u_int32_t tsf_low;
- u_int64_t tsf64;
+ a_int64_t tsf_delta; /* signed int64 */
tsf = ah->ah_getTsf64(ah);
- tsf_low = tsf & 0xffffffff;
- tsf64 = (tsf & ~0xffffffffULL) | rstamp;
+ tsf_low = tsf & 0xffffffffUL;
- if (rstamp > tsf_low && (rstamp - tsf_low > 0x10000000))
- tsf64 -= 0x100000000ULL;
+ tsf_delta = (a_int32_t)((rstamp - tsf_low) & 0xffffffffUL);
- if (rstamp < tsf_low && (tsf_low - rstamp > 0x10000000))
- tsf64 += 0x100000000ULL;
-
- return tsf64;
+ return (tsf + (u_int64_t)tsf_delta);
}
static a_int32_t ath_rate_setup(struct ath_softc_tgt *sc, a_uint32_t mode)