include/osmocom/gsm/lapdm.h

#ifndef _OSMOCOM_LAPDM_H
#define _OSMOCOM_LAPDM_H

#include <stdint.h>

#include <osmocom/core/timer.h>
#include <osmocom/core/msgb.h>
#include <osmocom/gsm/prim.h>

/*! \defgroup lapdm LAPDm implementation according to GSM TS 04.06
 *  @{
 */

/*! \file lapdm.h */

/* primitive related sutff */

/*! \brief LAPDm related primitives */
enum osmo_ph_prim {
	PRIM_PH_DATA,		/*!< \brief PH-DATA */
	PRIM_PH_RACH,		/*!< \brief PH-RANDOM_ACCESS */
	PRIM_PH_CONN,		/*!< \brief PH-CONNECT */
	PRIM_PH_EMPTY_FRAME,	/*!< \brief PH-EMPTY_FRAME */
	PRIM_PH_RTS,		/*!< \brief PH-RTS */
};

/*! \brief for PH-RANDOM_ACCESS.req */
struct ph_rach_req_param {
	uint8_t ra;		/*!< \brief Random Access */
	uint8_t ta;		/*!< \brief Timing Advance */
	uint8_t tx_power;	/*!< \brief Transmit Power */
	uint8_t is_combined_ccch;/*!< \brief Are we using a combined CCCH? */
	uint16_t offset;	/*!< \brief Timing Offset */
};

/*! \brief for PH-RANDOM_ACCESS.ind */
struct ph_rach_ind_param {
	uint8_t ra;		/*!< \brief Random Access */
	uint8_t acc_delay;	/*!< \brief Delay in bit periods */
	uint32_t fn;		/*!< \brief GSM Frame Number at time of RA */
};

/*! \brief for PH-[UNIT]DATA.{req,ind} */
struct ph_data_param {
	uint8_t link_id;	/*!< \brief Link Identifier (Like RSL) */
	uint8_t chan_nr;	/*!< \brief Channel Number (Like RSL) */
};

/*! \brief for PH-CONN.ind */
struct ph_conn_ind_param {
	uint32_t fn;		/*!< \brief GSM Frame Number */
};

/*! \brief primitive header for LAPDm PH-SAP primitives */
struct osmo_phsap_prim {
	struct osmo_prim_hdr oph; /*!< \brief generic primitive header */
	union {
		struct ph_data_param data;
		struct ph_rach_req_param rach_req;
		struct ph_rach_ind_param rach_ind;
		struct ph_conn_ind_param conn_ind;
	} u;			/*!< \brief request-specific data */
};

/*! \brief LAPDm mode/role */
enum lapdm_mode {
	LAPDM_MODE_MS,		/*!< \brief behave like a MS (mobile phone) */
	LAPDM_MODE_BTS,		/*!< \brief behave like a BTS (network) */
};

/*! \brief LAPDm state */
enum lapdm_state {
	LAPDm_STATE_NULL = 0,
	LAPDm_STATE_IDLE,
	LAPDm_STATE_SABM_SENT,
	LAPDm_STATE_MF_EST,
	LAPDm_STATE_TIMER_RECOV,
	LAPDm_STATE_DISC_SENT,
};

struct lapdm_entity;

/*! \brief LAPDm message context */
struct lapdm_msg_ctx {
	struct lapdm_datalink *dl;
	int lapdm_fmt;
	uint8_t n201;
	uint8_t chan_nr;
	uint8_t link_id;
	uint8_t addr;
	uint8_t ctrl;
	uint8_t ta_ind;
	uint8_t tx_power_ind;
};

/*! \brief LAPDm datalink like TS 04.06 / Section 3.5.2 */
struct lapdm_datalink {
	uint8_t V_send;	/*!< \brief seq nr of next I frame to be transmitted */
	uint8_t V_ack;	/*!< \brief last frame ACKed by peer */
	uint8_t N_send;	/*!< \brief ? set to V_send at Tx time*/
	uint8_t V_recv;	/*!< \brief seq nr of next I frame expected to be received */
	uint8_t N_recv;	/*!< \brief expected send seq nr of the next received I frame */
	uint32_t state; /*!< \brief LAPDm state (\ref lapdm_state) */
	int seq_err_cond; /*!< \brief condition of sequence error */
	uint8_t own_busy; /*!< \brief receiver busy on our side */
	uint8_t peer_busy; /*!< \brief receiver busy on remote side */
	struct osmo_timer_list t200; /*!< \brief T200 timer */
	uint8_t retrans_ctr; /*!< \brief re-transmission counter */
	struct llist_head send_queue; /*!< \brief frames from L3 */
	struct msgb *send_buffer; /*!< \brief current frame transmitting */
	int send_out; /*!< \brief how much was sent from send_buffer */
	uint8_t tx_hist[8][200]; /*!< \brief tx history buffer */
	int tx_length[8]; /*!< \brief length in history buffer */
	struct llist_head tx_queue; /*!< \brief frames to L1 */
	struct lapdm_msg_ctx mctx; /*!< \brief context of established connection */
	struct msgb *rcv_buffer; /*!< \brief buffer to assemble the received message */

	struct lapdm_entity *entity; /*!< \brief LAPDm entity we are part of */
};

/*! \brief LAPDm datalink SAPIs */
enum lapdm_dl_sapi {
	DL_SAPI0	= 0,	/*!< \brief SAPI 0 */
	DL_SAPI3	= 1,	/*!< \brief SAPI 1 */
	_NR_DL_SAPI
};

typedef int (*lapdm_cb_t)(struct msgb *msg, struct lapdm_entity *le, void *ctx);

struct lapdm_cr_ent {
	uint8_t cmd;
	uint8_t resp;
};

#define LAPDM_ENT_F_EMPTY_FRAME		0x0001
#define LAPDM_ENT_F_POLLING_ONLY	0x0002

/*! \brief a LAPDm Entity */
struct lapdm_entity {
	/*! \brief the SAPIs of the LAPDm entity */
	struct lapdm_datalink datalink[_NR_DL_SAPI];
	int last_tx_dequeue; /*!< \brief last entity that was dequeued */
	int tx_pending; /*!< \brief currently a pending frame not confirmed by L1 */
	enum lapdm_mode mode; /*!< \brief are we in BTS mode or MS mode */
	unsigned int flags;

	struct {
		/*! \brief filled-in once we set the lapdm_mode above */
		struct lapdm_cr_ent loc2rem;
		struct lapdm_cr_ent rem2loc;
	} cr;

	void *l1_ctx;	/*!< \brief context for layer1 instance */
	void *l3_ctx;	/*!< \brief context for layer3 instance */

	osmo_prim_cb l1_prim_cb;/*!< \brief callback for sending prims to L1 */
	lapdm_cb_t l3_cb;	/*!< \brief callback for sending stuff to L3 */

	/*! \brief pointer to \ref lapdm_channel of which we're part */
	struct lapdm_channel *lapdm_ch;
};

/*! \brief the two lapdm_entities that form a GSM logical channel (ACCH + DCCH) */
struct lapdm_channel {
	struct llist_head list;		/*!< \brief internal linked list */
	char *name;			/*!< \brief human-readable name */
	struct lapdm_entity lapdm_acch;	/*!< \brief Associated Control Channel */
	struct lapdm_entity lapdm_dcch;	/*!< \brief Dedicated Control Channel */
};

const char *get_rsl_name(int value);
extern const char *lapdm_state_names[];

/* initialize a LAPDm entity */
void lapdm_entity_init(struct lapdm_entity *le, enum lapdm_mode mode);
void lapdm_channel_init(struct lapdm_channel *lc, enum lapdm_mode mode);

/* deinitialize a LAPDm entity */
void lapdm_entity_exit(struct lapdm_entity *le);
void lapdm_channel_exit(struct lapdm_channel *lc);

/* input into layer2 (from layer 1) */
int lapdm_phsap_up(struct osmo_prim_hdr *oph, struct lapdm_entity *le);

/* input into layer2 (from layer 3) */
int lapdm_rslms_recvmsg(struct msgb *msg, struct lapdm_channel *lc);

void lapdm_channel_set_l3(struct lapdm_channel *lc, lapdm_cb_t cb, void *ctx);
void lapdm_channel_set_l1(struct lapdm_channel *lc, osmo_prim_cb cb, void *ctx);

int lapdm_entity_set_mode(struct lapdm_entity *le, enum lapdm_mode mode);
int lapdm_channel_set_mode(struct lapdm_channel *lc, enum lapdm_mode mode);

void lapdm_entity_reset(struct lapdm_entity *le);
void lapdm_channel_reset(struct lapdm_channel *lc);

void lapdm_entity_set_flags(struct lapdm_entity *le, unsigned int flags);
void lapdm_channel_set_flags(struct lapdm_channel *lc, unsigned int flags);

int lapdm_phsap_dequeue_prim(struct lapdm_entity *le, struct osmo_phsap_prim *pp);

/*! }@ */

#endif /* _OSMOCOM_LAPDM_H */