path: root/drivers/net/wireless/ath/ath9k/ath9k.h

/*
 * Copyright (c) 2008-2009 Atheros Communications Inc.
 *
 * 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.
 */

#ifndef ATH9K_H
#define ATH9K_H

#include <linux/etherdevice.h>
#include <linux/device.h>
#include <linux/leds.h>

#include "debug.h"
#include "common.h"

/*
 * Header for the ath9k.ko driver core *only* -- hw code nor any other driver
 * should rely on this file or its contents.
 */

struct ath_node;

/* Macro to expand scalars to 64-bit objects */

#define	ito64(x) (sizeof(x) == 1) ?			\
	(((unsigned long long int)(x)) & (0xff)) :	\
	(sizeof(x) == 2) ?				\
	(((unsigned long long int)(x)) & 0xffff) :	\
	((sizeof(x) == 4) ?				\
	 (((unsigned long long int)(x)) & 0xffffffff) : \
	 (unsigned long long int)(x))

/* increment with wrap-around */
#define INCR(_l, _sz)   do {			\
		(_l)++;				\
		(_l) &= ((_sz) - 1);		\
	} while (0)

/* decrement with wrap-around */
#define DECR(_l,  _sz)  do {			\
		(_l)--;				\
		(_l) &= ((_sz) - 1);		\
	} while (0)

#define A_MAX(a, b) ((a) > (b) ? (a) : (b))

#define TSF_TO_TU(_h,_l) \
	((((u32)(_h)) << 22) | (((u32)(_l)) >> 10))

#define	ATH_TXQ_SETUP(sc, i)        ((sc)->tx.txqsetup & (1<<i))

struct ath_config {
	u32 ath_aggr_prot;
	u16 txpowlimit;
	u8 cabqReadytime;
};

/*************************/
/* Descriptor Management */
/*************************/

#define ATH_TXBUF_RESET(_bf) do {				\
		(_bf)->bf_stale = false;			\
		(_bf)->bf_lastbf = NULL;			\
		(_bf)->bf_next = NULL;				\
		memset(&((_bf)->bf_state), 0,			\
		       sizeof(struct ath_buf_state));		\
	} while (0)

#define ATH_RXBUF_RESET(_bf) do {		\
		(_bf)->bf_stale = false;	\
	} while (0)

/**
 * enum buffer_type - Buffer type flags
 *
 * @BUF_HT: Send this buffer using HT capabilities
 * @BUF_AMPDU: This buffer is an ampdu, as part of an aggregate (during TX)
 * @BUF_AGGR: Indicates whether the buffer can be aggregated
 *	(used in aggregation scheduling)
 * @BUF_RETRY: Indicates whether the buffer is retried
 * @BUF_XRETRY: To denote excessive retries of the buffer
 */
enum buffer_type {
	BUF_HT			= BIT(1),
	BUF_AMPDU		= BIT(2),
	BUF_AGGR		= BIT(3),
	BUF_RETRY		= BIT(4),
	BUF_XRETRY		= BIT(5),
};

#define bf_nframes      	bf_state.bfs_nframes
#define bf_al           	bf_state.bfs_al
#define bf_frmlen       	bf_state.bfs_frmlen
#define bf_retries      	bf_state.bfs_retries
#define bf_seqno        	bf_state.bfs_seqno
#define bf_tidno        	bf_state.bfs_tidno
#define bf_keyix                bf_state.bfs_keyix
#define bf_keytype      	bf_state.bfs_keytype
#define bf_isht(bf)		(bf->bf_state.bf_type & BUF_HT)
#define bf_isampdu(bf)		(bf->bf_state.bf_type & BUF_AMPDU)
#define bf_isaggr(bf)		(bf->bf_state.bf_type & BUF_AGGR)
#define bf_isretried(bf)	(bf->bf_state.bf_type & BUF_RETRY)
#define bf_isxretried(bf)	(bf->bf_state.bf_type & BUF_XRETRY)

struct ath_descdma {
	struct ath_desc *dd_desc;
	dma_addr_t dd_desc_paddr;
	u32 dd_desc_len;
	struct ath_buf *dd_bufptr;
};

int ath_descdma_setup(struct ath_softc *sc, struct ath_descdma *dd,
		      struct list_head *head, const char *name,
		      int nbuf, int ndesc);
void ath_descdma_cleanup(struct ath_softc *sc, struct ath_descdma *dd,
			 struct list_head *head);

/***********/
/* RX / TX */
/***********/

#define ATH_MAX_ANTENNA         3
#define ATH_RXBUF               512
#define ATH_TXBUF               512
#define ATH_TXMAXTRY            13
#define ATH_MGT_TXMAXTRY        4

#define TID_TO_WME_AC(_tid)				\
	((((_tid) == 0) || ((_tid) == 3)) ? WME_AC_BE :	\
	 (((_tid) == 1) || ((_tid) == 2)) ? WME_AC_BK :	\
	 (((_tid) == 4) || ((_tid) == 5)) ? WME_AC_VI :	\
	 WME_AC_VO)

#define ADDBA_EXCHANGE_ATTEMPTS    10
#define ATH_AGGR_DELIM_SZ          4
#define ATH_AGGR_MINPLEN           256 /* in bytes, minimum packet length */
/* number of delimiters for encryption padding */
#define ATH_AGGR_ENCRYPTDELIM      10
/* minimum h/w qdepth to be sustained to maximize aggregation */
#define ATH_AGGR_MIN_QDEPTH        2
#define ATH_AMPDU_SUBFRAME_DEFAULT 32

#define IEEE80211_SEQ_SEQ_SHIFT    4
#define IEEE80211_SEQ_MAX          4096
#define IEEE80211_WEP_IVLEN        3
#define IEEE80211_WEP_KIDLEN       1
#define IEEE80211_WEP_CRCLEN       4
#define IEEE80211_MAX_MPDU_LEN     (3840 + FCS_LEN +		\
				    (IEEE80211_WEP_IVLEN +	\
				     IEEE80211_WEP_KIDLEN +	\
				     IEEE80211_WEP_CRCLEN))

/* return whether a bit at index _n in bitmap _bm is set
 * _sz is the size of the bitmap  */
#define ATH_BA_ISSET(_bm, _n)  (((_n) < (WME_BA_BMP_SIZE)) &&		\
				((_bm)[(_n) >> 5] & (1 << ((_n) & 31))))

/* return block-ack bitmap index given sequence and starting sequence */
#define ATH_BA_INDEX(_st, _seq) (((_seq) - (_st)) & (IEEE80211_SEQ_MAX - 1))

/* returns delimiter padding required given the packet length */
#define ATH_AGGR_GET_NDELIM(_len)					\
	(((((_len) + ATH_AGGR_DELIM_SZ) < ATH_AGGR_MINPLEN) ?           \
	  (ATH_AGGR_MINPLEN - (_len) - ATH_AGGR_DELIM_SZ) : 0) >> 2)

#define BAW_WITHIN(_start, _bawsz, _seqno) \
	((((_seqno) - (_start)) & 4095) < (_bawsz))

#define ATH_DS_BA_SEQ(_ds)         ((_ds)->ds_us.tx.ts_seqnum)
#define ATH_DS_BA_BITMAP(_ds)      (&(_ds)->ds_us.tx.ba_low)
#define ATH_DS_TX_BA(_ds)          ((_ds)->ds_us.tx.ts_flags & ATH9K_TX_BA)
#define ATH_AN_2_TID(_an, _tidno)  (&(_an)->tid[(_tidno)])

#define ATH_TX_COMPLETE_POLL_INT	1000

enum ATH_AGGR_STATUS {
	ATH_AGGR_DONE,
	ATH_AGGR_BAW_CLOSED,
	ATH_AGGR_LIMITED,
};

struct ath_txq {
	u32 axq_qnum;
	u32 *axq_link;
	struct list_head axq_q;
	spinlock_t axq_lock;
	u32 axq_depth;
	bool stopped;
	bool axq_tx_inprogress;
	struct list_head axq_acq;
};

#define AGGR_CLEANUP         BIT(1)
#define AGGR_ADDBA_COMPLETE  BIT(2)
#define AGGR_ADDBA_PROGRESS  BIT(3)

struct ath_tx_control {
	struct ath_txq *txq;
	int if_id;
	enum ath9k_internal_frame_type frame_type;
};

#define ATH_TX_ERROR        0x01
#define ATH_TX_XRETRY       0x02
#define ATH_TX_BAR          0x04

struct ath_tx {
	u16 seq_no;
	u32 txqsetup;
	int hwq_map[ATH9K_WME_AC_VO+1];
	spinlock_t txbuflock;
	struct list_head txbuf;
	struct ath_txq txq[ATH9K_NUM_TX_QUEUES];
	struct ath_descdma txdma;
};

struct ath_rx {
	u8 defant;
	u8 rxotherant;
	u32 *rxlink;
	unsigned int rxfilter;
	spinlock_t rxflushlock;
	spinlock_t rxbuflock;
	struct list_head rxbuf;
	struct ath_descdma rxdma;
};

int ath_startrecv(struct ath_softc *sc);
bool ath_stoprecv(struct ath_softc *sc);
void ath_flushrecv(struct ath_softc *sc);
u32 ath_calcrxfilter(struct ath_softc *sc);
int ath_rx_init(struct ath_softc *sc, int nbufs);
void ath_rx_cleanup(struct ath_softc *sc);
int ath_rx_tasklet(struct ath_softc *sc, int flush);
struct ath_txq *ath_txq_setup(struct ath_softc *sc, int qtype, int subtype);
void ath_tx_cleanupq(struct ath_softc *sc, struct ath_txq *txq);
int ath_tx_setup(struct ath_softc *sc, int haltype);
void ath_drain_all_txq(struct ath_softc *sc, bool retry_tx);
void ath_draintxq(struct ath_softc *sc,
		     struct ath_txq *txq, bool retry_tx);
void ath_tx_node_init(struct ath_softc *sc, struct ath_node *an);
void ath_tx_node_cleanup(struct ath_softc *sc, struct ath_node *an);
void ath_txq_schedule(struct ath_softc *sc, struct ath_txq *txq);
int ath_tx_init(struct ath_softc *sc, int nbufs);
void ath_tx_cleanup(struct ath_softc *sc);
struct ath_txq *ath_test_get_txq(struct ath_softc *sc, struct sk_buff *skb);
int ath_txq_update(struct ath_softc *sc, int qnum,
		   struct ath9k_tx_queue_info *q);
int ath_tx_start(struct ieee80211_hw *hw, struct sk_buff *skb,
		 struct ath_tx_control *txctl);
void ath_tx_tasklet(struct ath_softc *sc);
void ath_tx_cabq(struct ieee80211_hw *hw, struct sk_buff *skb);
bool ath_tx_aggr_check(struct ath_softc *sc, struct ath_node *an, u8 tidno);
void ath_tx_aggr_start(struct ath_softc *sc, struct ieee80211_sta *sta,
		       u16 tid, u16 *ssn);
void ath_tx_aggr_stop(struct ath_softc *sc, struct ieee80211_sta *sta, u16 tid);
void ath_tx_aggr_resume(struct ath_softc *sc, struct ieee80211_sta *sta, u16 tid);
void ath9k_enable_ps(struct ath_softc *sc);

/********/
/* VIFs */
/********/

struct ath_vif {
	int av_bslot;
	__le64 tsf_adjust; /* TSF adjustment for staggered beacons */
	enum nl80211_iftype av_opmode;
	struct ath_buf *av_bcbuf;
	struct ath_tx_control av_btxctl;
	u8 bssid[ETH_ALEN]; /* current BSSID from config_interface */
};

/*******************/
/* Beacon Handling */
/*******************/

/*
 * Regardless of the number of beacons we stagger, (i.e. regardless of the
 * number of BSSIDs) if a given beacon does not go out even after waiting this
 * number of beacon intervals, the game's up.
 */
#define BSTUCK_THRESH           	(9 * ATH_BCBUF)
#define	ATH_BCBUF               	4
#define ATH_DEFAULT_BINTVAL     	100 /* TU */
#define ATH_DEFAULT_BMISS_LIMIT 	10
#define IEEE80211_MS_TO_TU(x)           (((x) * 1000) / 1024)

struct ath_beacon_config {
	u16 beacon_interval;
	u16 listen_interval;
	u16 dtim_period;
	u16 bmiss_timeout;
	u8 dtim_count;
};

struct ath_beacon {
	enum {
		OK,		/* no change needed */
		UPDATE,		/* update pending */
		COMMIT		/* beacon sent, commit change */
	} updateslot;		/* slot time update fsm */

	u32 beaconq;
	u32 bmisscnt;
	u32 ast_be_xmit;
	u64 bc_tstamp;
	struct ieee80211_vif *bslot[ATH_BCBUF];
	struct ath_wiphy *bslot_aphy[ATH_BCBUF];
	int slottime;
	int slotupdate;
	struct ath9k_tx_queue_info beacon_qi;
	struct ath_descdma bdma;
	struct ath_txq *cabq;
	struct list_head bbuf;
};

void ath_beacon_tasklet(unsigned long data);
void ath_beacon_config(struct ath_softc *sc, struct ieee80211_vif *vif);
int ath_beacon_alloc(struct ath_wiphy *aphy, struct ieee80211_vif *vif);
void ath_beacon_return(struct ath_softc *sc, struct ath_vif *avp);
int ath_beaconq_config(struct ath_softc *sc);

/*******/
/* ANI */
/*******/

#define ATH_STA_SHORT_CALINTERVAL 1000    /* 1 second */
#define ATH_AP_SHORT_CALINTERVAL  100     /* 100 ms */
#define ATH_ANI_POLLINTERVAL      100     /* 100 ms */
#define ATH_LONG_CALINTERVAL      30000   /* 30 seconds */
#define ATH_RESTART_CALINTERVAL   1200000 /* 20 minutes */

void ath_ani_calibrate(unsigned long data);

/**********/
/* BTCOEX */
/**********/

/* Defines the BT AR_BT_COEX_WGHT used */
enum ath_stomp_type {
	ATH_BTCOEX_NO_STOMP,
	ATH_BTCOEX_STOMP_ALL,
	ATH_BTCOEX_STOMP_LOW,
	ATH_BTCOEX_STOMP_NONE
};

struct ath_btcoex {
	bool hw_timer_enabled;
	spinlock_t btcoex_lock;
	struct timer_list period_timer; /* Timer for BT period */
	u32 bt_priority_cnt;
	unsigned long bt_priority_time;
	int bt_stomp_type; /* Types of BT stomping */
	u32 btcoex_no_stomp; /* in usec */
	u32 btcoex_period; /* in usec */
	u32 btscan_no_stomp; /* in usec */
	struct ath_gen_timer *no_stomp_timer; /* Timer for no BT stomping */
};

int ath_init_btcoex_timer(struct ath_softc *sc);
void ath9k_btcoex_timer_resume(struct ath_softc *sc);
void ath9k_btcoex_timer_pause(struct ath_softc *sc);

/********************/
/*   LED Control    */
/********************/

#define ATH_LED_PIN_DEF 		1
#define ATH_LED_PIN_9287		8
#define ATH_LED_ON_DURATION_IDLE	350	/* in msecs */
#define ATH_LED_OFF_DURATION_IDLE	250	/* in msecs */

enum ath_led_type {
	ATH_LED_RADIO,
	ATH_LED_ASSOC,
	ATH_LED_TX,
	ATH_LED_RX
};

struct ath_led {
	struct ath_softc *sc;
	struct led_classdev led_cdev;
	enum ath_led_type led_type;
	char name[32];
	bool registered;
};

void ath_init_leds(struct ath_softc *sc);
void ath_deinit_leds(struct ath_softc *sc);

/********************/
/* Main driver core */
/********************/

/*
 * Default cache line size, in bytes.
 * Used when PCI device not fully initialized by bootrom/BIOS
*/
#define DEFAULT_CACHELINE       32
#define ATH_REGCLASSIDS_MAX     10
#define ATH_CABQ_READY_TIME     80      /* % of beacon interval */
#define ATH_MAX_SW_RETRIES      10
#define ATH_CHAN_MAX            255
#define IEEE80211_WEP_NKID      4       /* number of key ids */

#define ATH_TXPOWER_MAX         100     /* .5 dBm units */
#define ATH_RATE_DUMMY_MARKER   0

#define SC_OP_INVALID                BIT(0)
#define SC_OP_BEACONS                BIT(1)
#define SC_OP_RXAGGR                 BIT(2)
#define SC_OP_TXAGGR                 BIT(3)
#define SC_OP_FULL_RESET             BIT(4)
#define SC_OP_PREAMBLE_SHORT         BIT(5)
#define SC_OP_PROTECT_ENABLE         BIT(6)
#define SC_OP_RXFLUSH                BIT(7)
#define SC_OP_LED_ASSOCIATED         BIT(8)
#define SC_OP_LED_ON                 BIT(9)
#define SC_OP_SCANNING               BIT(10)
#define SC_OP_TSF_RESET              BIT(11)
#define SC_OP_BT_PRIORITY_DETECTED   BIT(12)
#define SC_OP_BT_SCAN		     BIT(13)

/* Powersave flags */
#define PS_WAIT_FOR_BEACON        BIT(0)
#define PS_WAIT_FOR_CAB           BIT(1)
#define PS_WAIT_FOR_PSPOLL_DATA   BIT(2)
#define PS_WAIT_FOR_TX_ACK        BIT(3)
#define PS_BEACON_SYNC            BIT(4)
#define PS_NULLFUNC_COMPLETED     BIT(5)
#define PS_ENABLED                BIT(6)

struct ath_wiphy;
struct ath_rate_table;

struct ath_softc {
	struct ieee80211_hw *hw;
	struct device *dev;

	spinlock_t wiphy_lock; /* spinlock to protect ath_wiphy data */
	struct ath_wiphy *pri_wiphy;
	struct ath_wiphy **sec_wiphy; /* secondary wiphys (virtual radios); may
				       * have NULL entries */
	int num_sec_wiphy; /* number of sec_wiphy pointers in the array */
	int chan_idx;
	int chan_is_ht;
	struct ath_wiphy *next_wiphy;
	struct work_struct chan_work;
	int wiphy_select_failures;
	unsigned long wiphy_select_first_fail;
	struct delayed_work wiphy_work;
	unsigned long wiphy_scheduler_int;
	int wiphy_scheduler_index;

	struct tasklet_struct intr_tq;
	struct tasklet_struct bcon_tasklet;
	struct ath_hw *sc_ah;
	void __iomem *mem;
	int irq;
	spinlock_t sc_resetlock;
	spinlock_t sc_serial_rw;
	spinlock_t sc_pm_lock;
	struct mutex mutex;

	u32 intrstatus;
	u32 sc_flags; /* SC_OP_* */
	u16 ps_flags; /* PS_* */
	u16 curtxpow;
	u8 nbcnvifs;
	u16 nvifs;
	bool ps_enabled;
	bool ps_idle;
	unsigned long ps_usecount;
	enum ath9k_int imask;

	struct ath_config config;
	struct ath_rx rx;
	struct ath_tx tx;
	struct ath_beacon beacon;
	const struct ath_rate_table *cur_rate_table;
	enum wireless_mode cur_rate_mode;
	struct ieee80211_supported_band sbands[IEEE80211_NUM_BANDS];

	struct ath_led radio_led;
	struct ath_led assoc_led;
	struct ath_led tx_led;
	struct ath_led rx_led;
	struct delayed_work ath_led_blink_work;
	int led_on_duration;
	int led_off_duration;
	int led_on_cnt;
	int led_off_cnt;

	int beacon_interval;

#ifdef CONFIG_ATH9K_DEBUGFS
	struct ath9k_debug debug;
#endif
	struct ath_beacon_config cur_beacon_conf;
	struct delayed_work tx_complete_work;
	struct ath_btcoex btcoex;
};

struct ath_wiphy {
	struct ath_softc *sc; /* shared for all virtual wiphys */
	struct ieee80211_hw *hw;
	enum ath_wiphy_state {
		ATH_WIPHY_INACTIVE,
		ATH_WIPHY_ACTIVE,
		ATH_WIPHY_PAUSING,
		ATH_WIPHY_PAUSED,
		ATH_WIPHY_SCAN,
	} state;
	bool idle;
	int chan_idx;
	int chan_is_ht;
};

void ath9k_tasklet(unsigned long data);
int ath_reset(struct ath_softc *sc, bool retry_tx);
int ath_get_hal_qnum(u16 queue, struct ath_softc *sc);
int ath_get_mac80211_qnum(u32 queue, struct ath_softc *sc);
int ath_cabq_update(struct ath_softc *);

static inline void ath_read_cachesize(struct ath_common *common, int *csz)
{
	common->bus_ops->read_cachesize(common, csz);
}

extern struct ieee80211_ops ath9k_ops;
extern int modparam_nohwcrypt;

irqreturn_t ath_isr(int irq, void *dev);
int ath9k_init_device(u16 devid, struct ath_softc *sc, u16 subsysid,
		    const struct ath_bus_ops *bus_ops);
void ath9k_deinit_device(struct ath_softc *sc);
const char *ath_mac_bb_name(u32 mac_bb_version);
const char *ath_rf_name(u16 rf_version);
void ath9k_set_hw_capab(struct ath_softc *sc, struct ieee80211_hw *hw);
void ath9k_update_ichannel(struct ath_softc *sc, struct ieee80211_hw *hw,
			   struct ath9k_channel *ichan);
void ath_update_chainmask(struct ath_softc *sc, int is_ht);
int ath_set_channel(struct ath_softc *sc, struct ieee80211_hw *hw,
		    struct ath9k_channel *hchan);

void ath_radio_enable(struct ath_softc *sc, struct ieee80211_hw *hw);
void ath_radio_disable(struct ath_softc *sc, struct ieee80211_hw *hw);
bool ath9k_setpower(struct ath_softc *sc, enum ath9k_power_mode mode);

#ifdef CONFIG_PCI
int ath_pci_init(void);
void ath_pci_exit(void);
#else
static inline int ath_pci_init(void) { return 0; };
static inline void ath_pci_exit(void) {};
#endif

#ifdef CONFIG_ATHEROS_AR71XX
int ath_ahb_init(void);
void ath_ahb_exit(void);
#else
static inline int ath_ahb_init(void) { return 0; };
static inline void ath_ahb_exit(void) {};
#endif

void ath9k_ps_wakeup(struct ath_softc *sc);
void ath9k_ps_restore(struct ath_softc *sc);

void ath9k_set_bssid_mask(struct ieee80211_hw *hw);
int ath9k_wiphy_add(struct ath_softc *sc);
int ath9k_wiphy_del(struct ath_wiphy *aphy);
void ath9k_tx_status(struct ieee80211_hw *hw, struct sk_buff *skb);
int ath9k_wiphy_pause(struct ath_wiphy *aphy);
int ath9k_wiphy_unpause(struct ath_wiphy *aphy);
int ath9k_wiphy_select(struct ath_wiphy *aphy);
void ath9k_wiphy_set_scheduler(struct ath_softc *sc, unsigned int msec_int);
void ath9k_wiphy_chan_work(struct work_struct *work);
bool ath9k_wiphy_started(struct ath_softc *sc);
void ath9k_wiphy_pause_all_forced(struct ath_softc *sc,
				  struct ath_wiphy *selected);
bool ath9k_wiphy_scanning(struct ath_softc *sc);
void ath9k_wiphy_work(struct work_struct *work);
bool ath9k_all_wiphys_idle(struct ath_softc *sc);
void ath9k_set_wiphy_idle(struct ath_wiphy *aphy, bool idle);

void ath_mac80211_stop_queue(struct ath_softc *sc, u16 skb_queue);
void ath_mac80211_start_queue(struct ath_softc *sc, u16 skb_queue);

int ath_tx_get_qnum(struct ath_softc *sc, int qtype, int haltype);

void ath_start_rfkill_poll(struct ath_softc *sc);
extern void ath9k_rfkill_poll_state(struct ieee80211_hw *hw);

#endif /* ATH9K_H */