drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c

Source file repositories/reference/linux-study-clean/drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c

File Facts

System
Linux kernel
Corpus path
drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c
Extension
.c
Size
58029 bytes
Lines
1929
Domain
Driver Families
Bucket
drivers/net
Inferred role
Driver Families: implementation source
Status
source 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

struct iwl_mvm_mac_iface_iterator_data {
	struct iwl_mvm *mvm;
	struct ieee80211_vif *vif;
	unsigned long available_mac_ids[BITS_TO_LONGS(NUM_MAC_INDEX_DRIVER)];
	unsigned long available_tsf_ids[BITS_TO_LONGS(NUM_TSF_IDS)];
	enum iwl_tsf_id preferred_tsf;
	bool found_vif;
};

static void iwl_mvm_mac_tsf_id_iter(void *_data, u8 *mac,
				    struct ieee80211_vif *vif)
{
	struct iwl_mvm_mac_iface_iterator_data *data = _data;
	struct iwl_mvm_vif *mvmvif = iwl_mvm_vif_from_mac80211(vif);
	u16 min_bi;

	/* Skip the interface for which we are trying to assign a tsf_id  */
	if (vif == data->vif)
		return;

	/*
	 * The TSF is a hardware/firmware resource, there are 4 and
	 * the driver should assign and free them as needed. However,
	 * there are cases where 2 MACs should share the same TSF ID
	 * for the purpose of clock sync, an optimization to avoid
	 * clock drift causing overlapping TBTTs/DTIMs for a GO and
	 * client in the system.
	 *
	 * The firmware will decide according to the MAC type which
	 * will be the leader and follower. Clients that need to sync
	 * with a remote station will be the leader, and an AP or GO
	 * will be the follower.
	 *
	 * Depending on the new interface type it can be following
	 * or become the leader of an existing interface.
	 */
	switch (data->vif->type) {
	case NL80211_IFTYPE_STATION:
		/*
		 * The new interface is a client, so if the one we're iterating
		 * is an AP, and the beacon interval of the AP is a multiple or
		 * divisor of the beacon interval of the client, the same TSF
		 * should be used to avoid drift between the new client and
		 * existing AP. The existing AP will get drift updates from the
		 * new client context in this case.
		 */
		if (vif->type != NL80211_IFTYPE_AP ||
		    data->preferred_tsf != NUM_TSF_IDS ||
		    !test_bit(mvmvif->tsf_id, data->available_tsf_ids))
			break;

		min_bi = min(data->vif->bss_conf.beacon_int,
			     vif->bss_conf.beacon_int);

		if (!min_bi)
			break;

		if ((data->vif->bss_conf.beacon_int -
		     vif->bss_conf.beacon_int) % min_bi == 0) {
			data->preferred_tsf = mvmvif->tsf_id;
			return;
		}
		break;

	case NL80211_IFTYPE_AP:
		/*
		 * The new interface is AP/GO, so if its beacon interval is a
		 * multiple or a divisor of the beacon interval of an existing
		 * interface, it should get drift updates from an existing
		 * client or use the same TSF as an existing GO. There's no
		 * drift between TSFs internally but if they used different
		 * TSFs then a new client MAC could update one of them and
		 * cause drift that way.
		 */
		if ((vif->type != NL80211_IFTYPE_AP &&
		     vif->type != NL80211_IFTYPE_STATION) ||
		    data->preferred_tsf != NUM_TSF_IDS ||
		    !test_bit(mvmvif->tsf_id, data->available_tsf_ids))
			break;

		min_bi = min(data->vif->bss_conf.beacon_int,
			     vif->bss_conf.beacon_int);

		if (!min_bi)
			break;

		if ((data->vif->bss_conf.beacon_int -
		     vif->bss_conf.beacon_int) % min_bi == 0) {
			data->preferred_tsf = mvmvif->tsf_id;
			return;

Annotation

Implementation Notes