drivers/net/wireless/ath/ath9k/common-beacon.c

Source file repositories/reference/linux-study-clean/drivers/net/wireless/ath/ath9k/common-beacon.c

File Facts

System
Linux kernel
Corpus path
drivers/net/wireless/ath/ath9k/common-beacon.c
Extension
.c
Size
5488 bytes
Lines
168
Domain
Driver Families
Bucket
drivers/net
Inferred role
Driver Families: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

#include <linux/export.h>
#include "common.h"

#define FUDGE 2

static u32 ath9k_get_next_tbtt(struct ath_hw *ah, u64 tsf,
			       unsigned int interval)
{
	unsigned int offset, divisor;

	tsf += TU_TO_USEC(FUDGE + ah->config.sw_beacon_response_time);
	divisor = TU_TO_USEC(interval);
	div_u64_rem(tsf, divisor, &offset);

	return (u32) tsf + divisor - offset;
}

/*
 * This sets up the beacon timers according to the timestamp of the last
 * received beacon and the current TSF, configures PCF and DTIM
 * handling, programs the sleep registers so the hardware will wakeup in
 * time to receive beacons, and configures the beacon miss handling so
 * we'll receive a BMISS interrupt when we stop seeing beacons from the AP
 * we've associated with.
 */
int ath9k_cmn_beacon_config_sta(struct ath_hw *ah,
				 struct ath_beacon_config *conf,
				 struct ath9k_beacon_state *bs)
{
	struct ath_common *common = ath9k_hw_common(ah);
	int dtim_intval;
	u64 tsf;

	/* No need to configure beacon if we are not associated */
	if (!test_bit(ATH_OP_PRIM_STA_VIF, &common->op_flags)) {
		ath_dbg(common, BEACON,
			"STA is not yet associated..skipping beacon config\n");
		return -EPERM;
	}

	memset(bs, 0, sizeof(*bs));
	conf->intval = conf->beacon_interval;

	/*
	 * Setup dtim parameters according to
	 * last beacon we received (which may be none).
	 */
	dtim_intval = conf->intval * conf->dtim_period;

	/*
	 * Pull nexttbtt forward to reflect the current
	 * TSF and calculate dtim state for the result.
	 */
	tsf = ath9k_hw_gettsf64(ah);
	conf->nexttbtt = ath9k_get_next_tbtt(ah, tsf, conf->intval);

	bs->bs_intval = TU_TO_USEC(conf->intval);
	bs->bs_dtimperiod = conf->dtim_period * bs->bs_intval;
	bs->bs_nexttbtt = conf->nexttbtt;
	bs->bs_nextdtim = conf->nexttbtt;
	if (conf->dtim_period > 1)
		bs->bs_nextdtim = ath9k_get_next_tbtt(ah, tsf, dtim_intval);

	/*
	 * Calculate the number of consecutive beacons to miss* before taking
	 * a BMISS interrupt. The configuration is specified in TU so we only
	 * need calculate based	on the beacon interval.  Note that we clamp the
	 * result to at most 15 beacons.
	 */
	bs->bs_bmissthreshold = DIV_ROUND_UP(conf->bmiss_timeout, conf->intval);
	if (bs->bs_bmissthreshold > 15)
		bs->bs_bmissthreshold = 15;
	else if (bs->bs_bmissthreshold <= 0)
		bs->bs_bmissthreshold = 1;

	/*
	 * Calculate sleep duration. The configuration is given in ms.
	 * We ensure a multiple of the beacon period is used. Also, if the sleep
	 * duration is greater than the DTIM period then it makes senses
	 * to make it a multiple of that.
	 *
	 * XXX fixed at 100ms
	 */

	bs->bs_sleepduration = TU_TO_USEC(roundup(IEEE80211_MS_TO_TU(100),
						  conf->intval));
	if (bs->bs_sleepduration > bs->bs_dtimperiod)
		bs->bs_sleepduration = bs->bs_dtimperiod;

	/* TSF out of range threshold fixed at 1 second */

Annotation

Implementation Notes