linux/drivers/isdn/hisax/hisax_isac.c

/*
 * Driver for ISAC-S and ISAC-SX
 * ISDN Subscriber Access Controller for Terminals
 *
 * Author       Kai Germaschewski
 * Copyright    2001 by Kai Germaschewski  <kai.germaschewski@gmx.de>
 *              2001 by Karsten Keil       <keil@isdn4linux.de>
 *
 * based upon Karsten Keil's original isac.c driver
 *
 * This software may be used and distributed according to the terms
 * of the GNU General Public License, incorporated herein by reference.
 *
 * Thanks to Wizard Computersysteme GmbH, Bremervoerde and
 *           SoHaNet Technology GmbH, Berlin
 * for supporting the development of this driver
 */

/* TODO:
 * specifically handle level vs edge triggered?
 */

#include <linux/module.h>
#include <linux/gfp.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include "hisax_isac.h"

// debugging cruft

#define __debug_variable debug
#include "hisax_debug.h"

#ifdef CONFIG_HISAX_DEBUG
static int debug = 1;
module_param(debug, int, 0);

static char *ISACVer[] = {
	"2086/2186 V1.1",
	"2085 B1",
	"2085 B2",
	"2085 V2.3"
};
#endif

MODULE_AUTHOR("Kai Germaschewski <kai.germaschewski@gmx.de>/Karsten Keil <kkeil@suse.de>");
MODULE_DESCRIPTION("ISAC/ISAC-SX driver");
MODULE_LICENSE("GPL");

#define DBG_WARN      0x0001
#define DBG_IRQ       0x0002
#define DBG_L1M       0x0004
#define DBG_PR        0x0008
#define DBG_RFIFO     0x0100
#define DBG_RPACKET   0x0200
#define DBG_XFIFO     0x1000
#define DBG_XPACKET   0x2000

// we need to distinguish ISAC-S and ISAC-SX
#define TYPE_ISAC        0x00
#define TYPE_ISACSX      0x01

// registers etc.
#define ISAC_MASK        0x20
#define ISAC_ISTA        0x20
#define ISAC_ISTA_EXI    0x01
#define ISAC_ISTA_SIN    0x02
#define ISAC_ISTA_CISQ   0x04
#define ISAC_ISTA_XPR    0x10
#define ISAC_ISTA_RSC    0x20
#define ISAC_ISTA_RPF    0x40
#define ISAC_ISTA_RME    0x80

#define ISAC_STAR        0x21
#define ISAC_CMDR        0x21
#define ISAC_CMDR_XRES   0x01
#define ISAC_CMDR_XME    0x02
#define ISAC_CMDR_XTF    0x08
#define ISAC_CMDR_RRES   0x40
#define ISAC_CMDR_RMC    0x80

#define ISAC_EXIR        0x24
#define ISAC_EXIR_MOS    0x04
#define ISAC_EXIR_XDU    0x40
#define ISAC_EXIR_XMR    0x80

#define ISAC_ADF2        0x39
#define ISAC_SPCR        0x30
#define ISAC_ADF1        0x38

#define ISAC_CIR0        0x31
#define ISAC_CIX0        0x31
#define ISAC_CIR0_CIC0   0x02
#define ISAC_CIR0_CIC1   0x01

#define ISAC_CIR1        0x33
#define ISAC_CIX1        0x33
#define ISAC_STCR        0x37
#define ISAC_MODE        0x22

#define ISAC_RSTA        0x27
#define ISAC_RSTA_RDO    0x40
#define ISAC_RSTA_CRC    0x20
#define ISAC_RSTA_RAB    0x10

#define ISAC_RBCL 0x25
#define ISAC_RBCH 0x2A
#define ISAC_TIMR 0x23
#define ISAC_SQXR 0x3b
#define ISAC_MOSR 0x3a
#define ISAC_MOCR 0x3a
#define ISAC_MOR0 0x32
#define ISAC_MOX0 0x32
#define ISAC_MOR1 0x34
#define ISAC_MOX1 0x34

#define ISAC_RBCH_XAC 0x80

#define ISAC_CMD_TIM    0x0
#define ISAC_CMD_RES    0x1
#define ISAC_CMD_SSP    0x2
#define ISAC_CMD_SCP    0x3
#define ISAC_CMD_AR8    0x8
#define ISAC_CMD_AR10   0x9
#define ISAC_CMD_ARL    0xa
#define ISAC_CMD_DI     0xf

#define ISACSX_MASK       0x60
#define ISACSX_ISTA       0x60
#define ISACSX_ISTA_ICD   0x01
#define ISACSX_ISTA_CIC   0x10

#define ISACSX_MASKD      0x20
#define ISACSX_ISTAD      0x20
#define ISACSX_ISTAD_XDU  0x04
#define ISACSX_ISTAD_XMR  0x08
#define ISACSX_ISTAD_XPR  0x10
#define ISACSX_ISTAD_RFO  0x20
#define ISACSX_ISTAD_RPF  0x40
#define ISACSX_ISTAD_RME  0x80

#define ISACSX_CMDRD      0x21
#define ISACSX_CMDRD_XRES 0x01
#define ISACSX_CMDRD_XME  0x02
#define ISACSX_CMDRD_XTF  0x08
#define ISACSX_CMDRD_RRES 0x40
#define ISACSX_CMDRD_RMC  0x80

#define ISACSX_MODED      0x22

#define ISACSX_RBCLD      0x26

#define ISACSX_RSTAD      0x28
#define ISACSX_RSTAD_RAB  0x10
#define ISACSX_RSTAD_CRC  0x20
#define ISACSX_RSTAD_RDO  0x40
#define ISACSX_RSTAD_VFR  0x80

#define ISACSX_CIR0       0x2e
#define ISACSX_CIR0_CIC0  0x08
#define ISACSX_CIX0       0x2e

#define ISACSX_TR_CONF0   0x30

#define ISACSX_TR_CONF2   0x32

static struct Fsm l1fsm;

enum {
	ST_L1_RESET,
	ST_L1_F3_PDOWN,
	ST_L1_F3_PUP,
	ST_L1_F3_PEND_DEACT,
	ST_L1_F4,
	ST_L1_F5,
	ST_L1_F6,
	ST_L1_F7,
	ST_L1_F8,
};

#define L1_STATE_COUNT (ST_L1_F8 + 1)

static char *strL1State[] =
{
	"ST_L1_RESET",
	"ST_L1_F3_PDOWN",
	"ST_L1_F3_PUP",
	"ST_L1_F3_PEND_DEACT",
	"ST_L1_F4",
	"ST_L1_F5",
	"ST_L1_F6",
	"ST_L1_F7",
	"ST_L1_F8",
};

enum {
	EV_PH_DR,           // 0000
	EV_PH_RES,          // 0001
	EV_PH_TMA,          // 0010
	EV_PH_SLD,          // 0011
	EV_PH_RSY,          // 0100
	EV_PH_DR6,          // 0101
	EV_PH_EI,           // 0110
	EV_PH_PU,           // 0111
	EV_PH_AR,           // 1000
	EV_PH_9,            // 1001
	EV_PH_ARL,          // 1010
	EV_PH_CVR,          // 1011
	EV_PH_AI8,          // 1100
	EV_PH_AI10,         // 1101
	EV_PH_AIL,          // 1110
	EV_PH_DC,           // 1111
	EV_PH_ACTIVATE_REQ,
	EV_PH_DEACTIVATE_REQ,
	EV_TIMER3,
};

#define L1_EVENT_COUNT (EV_TIMER3 + 1)

static char *strL1Event[] =
{
	"EV_PH_DR",           // 0000
	"EV_PH_RES",          // 0001
	"EV_PH_TMA",          // 0010
	"EV_PH_SLD",          // 0011
	"EV_PH_RSY",          // 0100
	"EV_PH_DR6",          // 0101
	"EV_PH_EI",           // 0110
	"EV_PH_PU",           // 0111
	"EV_PH_AR",           // 1000
	"EV_PH_9",            // 1001
	"EV_PH_ARL",          // 1010
	"EV_PH_CVR",          // 1011
	"EV_PH_AI8",          // 1100
	"EV_PH_AI10",         // 1101
	"EV_PH_AIL",          // 1110
	"EV_PH_DC",           // 1111
	"EV_PH_ACTIVATE_REQ",
	"EV_PH_DEACTIVATE_REQ",
	"EV_TIMER3",
};

static inline void D_L1L2(struct isac *isac, int pr, void *arg)
{
	struct hisax_if *ifc = (struct hisax_if *) &isac->hisax_d_if;

	DBG(DBG_PR, "pr %#x", pr);
	ifc->l1l2(ifc, pr, arg);
}

static void ph_command(struct isac *isac, unsigned int command)
{
	DBG(DBG_L1M, "ph_command %#x", command);
	switch (isac->type) {
	case TYPE_ISAC:
		isac->write_isac(isac, ISAC_CIX0, (command << 2) | 3);
		break;
	case TYPE_ISACSX:
		isac->write_isac(isac, ISACSX_CIX0, (command << 4) | (7 << 1));
		break;
	}
}

// ----------------------------------------------------------------------

static void l1_di(struct FsmInst *fi, int event, void *arg)
{
	struct isac *isac = fi->userdata;

	FsmChangeState(fi, ST_L1_RESET);
	ph_command(isac, ISAC_CMD_DI);
}

static void l1_di_deact_ind(struct FsmInst *fi, int event, void *arg)
{
	struct isac *isac = fi->userdata;

	FsmChangeState(fi, ST_L1_RESET);
	D_L1L2(isac, PH_DEACTIVATE | INDICATION, NULL);
	ph_command(isac, ISAC_CMD_DI);
}

static void l1_go_f3pdown(struct FsmInst *fi, int event, void *arg)
{
	FsmChangeState(fi, ST_L1_F3_PDOWN);
}

static void l1_go_f3pend_deact_ind(struct FsmInst *fi, int event, void *arg)
{
	struct isac *isac = fi->userdata;

	FsmChangeState(fi, ST_L1_F3_PEND_DEACT);
	D_L1L2(isac, PH_DEACTIVATE | INDICATION, NULL);
	ph_command(isac, ISAC_CMD_DI);
}

static void l1_go_f3pend(struct FsmInst *fi, int event, void *arg)
{
	struct isac *isac = fi->userdata;

	FsmChangeState(fi, ST_L1_F3_PEND_DEACT);
	ph_command(isac, ISAC_CMD_DI);
}

static void l1_go_f4(struct FsmInst *fi, int event, void *arg)
{
	FsmChangeState(fi, ST_L1_F4);
}

static void l1_go_f5(struct FsmInst *fi, int event, void *arg)
{
	FsmChangeState(fi, ST_L1_F5);
}

static void l1_go_f6(struct FsmInst *fi, int event, void *arg)
{
	FsmChangeState(fi, ST_L1_F6);
}

static void l1_go_f6_deact_ind(struct FsmInst *fi, int event, void *arg)
{
	struct isac *isac = fi->userdata;

	FsmChangeState(fi, ST_L1_F6);
	D_L1L2(isac, PH_DEACTIVATE | INDICATION, NULL);
}

static void l1_go_f7_act_ind(struct FsmInst *fi, int event, void *arg)
{
	struct isac *isac = fi->userdata;

	FsmDelTimer(&isac->timer, 0);
	FsmChangeState(fi, ST_L1_F7);
	ph_command(isac, ISAC_CMD_AR8);
	D_L1L2(isac, PH_ACTIVATE | INDICATION, NULL);
}

static void l1_go_f8(struct FsmInst *fi, int event, void *arg)
{
	FsmChangeState(fi, ST_L1_F8);
}

static void l1_go_f8_deact_ind(struct FsmInst *fi, int event, void *arg)
{
	struct isac *isac = fi->userdata;

	FsmChangeState(fi, ST_L1_F8);
	D_L1L2(isac, PH_DEACTIVATE | INDICATION, NULL);
}

static void l1_ar8(struct FsmInst *fi, int event, void *arg)
{
	struct isac *isac = fi->userdata;

	FsmRestartTimer(&isac->timer, TIMER3_VALUE, EV_TIMER3, NULL, 2);
	ph_command(isac, ISAC_CMD_AR8);
}

static void l1_timer3(struct FsmInst *fi, int event, void *arg)
{
	struct isac *isac = fi->userdata;

	ph_command(isac, ISAC_CMD_DI);
	D_L1L2(isac, PH_DEACTIVATE | INDICATION, NULL);
}

// state machines according to data sheet PSB 2186 / 3186

static struct FsmNode L1FnList[] __initdata =
{
	{ST_L1_RESET,         EV_PH_RES,            l1_di},
	{ST_L1_RESET,         EV_PH_EI,             l1_di},
	{ST_L1_RESET,         EV_PH_DC,             l1_go_f3pdown},
	{ST_L1_RESET,         EV_PH_AR,             l1_go_f6},
	{ST_L1_RESET,         EV_PH_AI8,            l1_go_f7_act_ind},

	{ST_L1_F3_PDOWN,      EV_PH_RES,            l1_di},
	{ST_L1_F3_PDOWN,      EV_PH_EI,             l1_di},
	{ST_L1_F3_PDOWN,      EV_PH_AR,             l1_go_f6},
	{ST_L1_F3_PDOWN,      EV_PH_RSY,            l1_go_f5},
	{ST_L1_F3_PDOWN,      EV_PH_PU,             l1_go_f4},
	{ST_L1_F3_PDOWN,      EV_PH_AI8,            l1_go_f7_act_ind},
	{ST_L1_F3_PDOWN,      EV_PH_ACTIVATE_REQ,   l1_ar8},
	{ST_L1_F3_PDOWN,      EV_TIMER3,            l1_timer3},

	{ST_L1_F3_PEND_DEACT, EV_PH_RES,            l1_di},
	{ST_L1_F3_PEND_DEACT, EV_PH_EI,             l1_di},
	{ST_L1_F3_PEND_DEACT, EV_PH_DC,             l1_go_f3pdown},
	{ST_L1_F3_PEND_DEACT, EV_PH_RSY,            l1_go_f5},
	{ST_L1_F3_PEND_DEACT, EV_PH_AR,             l1_go_f6},
	{ST_L1_F3_PEND_DEACT, EV_PH_AI8,            l1_go_f7_act_ind},

	{ST_L1_F4,            EV_PH_RES,            l1_di},
	{ST_L1_F4,            EV_PH_EI,             l1_di},
	{ST_L1_F4,            EV_PH_RSY,            l1_go_f5},
	{ST_L1_F4,            EV_PH_AI8,            l1_go_f7_act_ind},
	{ST_L1_F4,            EV_TIMER3,            l1_timer3},
	{ST_L1_F4,            EV_PH_DC,             l1_go_f3pdown},

	{ST_L1_F5,            EV_PH_RES,            l1_di},
	{ST_L1_F5,            EV_PH_EI,             l1_di},
	{ST_L1_F5,            EV_PH_AR,             l1_go_f6},
	{ST_L1_F5,            EV_PH_AI8,            l1_go_f7_act_ind},
	{ST_L1_F5,            EV_TIMER3,            l1_timer3},
	{ST_L1_F5,            EV_PH_DR,             l1_go_f3pend},
	{ST_L1_F5,            EV_PH_DC,             l1_go_f3pdown},

	{ST_L1_F6,            EV_PH_RES,            l1_di},
	{ST_L1_F6,            EV_PH_EI,             l1_di},
	{ST_L1_F6,            EV_PH_RSY,            l1_go_f8},
	{ST_L1_F6,            EV_PH_AI8,            l1_go_f7_act_ind},
	{ST_L1_F6,            EV_PH_DR6,            l1_go_f3pend},
	{ST_L1_F6,            EV_TIMER3,            l1_timer3},
	{ST_L1_F6,            EV_PH_DC,             l1_go_f3pdown},

	{ST_L1_F7,            EV_PH_RES,            l1_di_deact_ind},
	{ST_L1_F7,            EV_PH_EI,             l1_di_deact_ind},
	{ST_L1_F7,            EV_PH_AR,             l1_go_f6_deact_ind},
	{ST_L1_F7,            EV_PH_RSY,            l1_go_f8_deact_ind},
	{ST_L1_F7,            EV_PH_DR,             l1_go_f3pend_deact_ind},

	{ST_L1_F8,            EV_PH_RES,            l1_di},
	{ST_L1_F8,            EV_PH_EI,             l1_di},
	{ST_L1_F8,            EV_PH_AR,             l1_go_f6},
	{ST_L1_F8,            EV_PH_DR,             l1_go_f3pend},
	{ST_L1_F8,            EV_PH_AI8,            l1_go_f7_act_ind},
	{ST_L1_F8,            EV_TIMER3,            l1_timer3},
	{ST_L1_F8,            EV_PH_DC,             l1_go_f3pdown},
};

static void l1m_debug(struct FsmInst *fi, char *fmt, ...)
{
	va_list args;
	char buf[256];

	va_start(args, fmt);
	vsnprintf(buf, sizeof(buf), fmt, args);
	DBG(DBG_L1M, "%s", buf);
	va_end(args);
}

static void isac_version(struct isac *cs)
{
	int val;

	val = cs->read_isac(cs, ISAC_RBCH);
	DBG(1, "ISAC version (%x): %s", val, ISACVer[(val >> 5) & 3]);
}

static void isac_empty_fifo(struct isac *isac, int count)
{
	// this also works for isacsx, since
	// CMDR(D) register works the same
	u_char *ptr;

	DBG(DBG_IRQ, "count %d", count);

	if ((isac->rcvidx + count) >= MAX_DFRAME_LEN_L1) {
		DBG(DBG_WARN, "overrun %d", isac->rcvidx + count);
		isac->write_isac(isac, ISAC_CMDR, ISAC_CMDR_RMC);
		isac->rcvidx = 0;
		return;
	}
	ptr = isac->rcvbuf + isac->rcvidx;
	isac->rcvidx += count;
	isac->read_isac_fifo(isac, ptr, count);
	isac->write_isac(isac, ISAC_CMDR, ISAC_CMDR_RMC);
	DBG_PACKET(DBG_RFIFO, ptr, count);
}

static void isac_fill_fifo(struct isac *isac)
{
	// this also works for isacsx, since
	// CMDR(D) register works the same

	int count;
	unsigned char cmd;
	u_char *ptr;

	BUG_ON(!isac->tx_skb);

	count = isac->tx_skb->len;
	BUG_ON(count <= 0);

	DBG(DBG_IRQ, "count %d", count);

	if (count > 0x20) {
		count = 0x20;
		cmd = ISAC_CMDR_XTF;
	} else {
		cmd = ISAC_CMDR_XTF | ISAC_CMDR_XME;
	}

	ptr = isac->tx_skb->data;
	skb_pull(isac->tx_skb, count);
	isac->tx_cnt += count;
	DBG_PACKET(DBG_XFIFO, ptr, count);
	isac->write_isac_fifo(isac, ptr, count);
	isac->write_isac(isac, ISAC_CMDR, cmd);
}

static void isac_retransmit(struct isac *isac)
{
	if (!isac->tx_skb) {
		DBG(DBG_WARN, "no skb");
		return;
	}
	skb_push(isac->tx_skb, isac->tx_cnt);
	isac->tx_cnt = 0;
}


static inline void isac_cisq_interrupt(struct isac *isac)
{
	unsigned char val;

	val = isac->read_isac(isac, ISAC_CIR0);
	DBG(DBG_IRQ, "CIR0 %#x", val);
	if (val & ISAC_CIR0_CIC0) {
		DBG(DBG_IRQ, "CODR0 %#x", (val >> 2) & 0xf);
		FsmEvent(&isac->l1m, (val >> 2) & 0xf, NULL);
	}
	if (val & ISAC_CIR0_CIC1) {
		val = isac->read_isac(isac, ISAC_CIR1);
		DBG(DBG_WARN, "ISAC CIR1 %#x", val);
	}
}

static inline void isac_rme_interrupt(struct isac *isac)
{
	unsigned char val;
	int count;
	struct sk_buff *skb;

	val = isac->read_isac(isac, ISAC_RSTA);
	if ((val & (ISAC_RSTA_RDO | ISAC_RSTA_CRC | ISAC_RSTA_RAB))
	    != ISAC_RSTA_CRC) {
		DBG(DBG_WARN, "RSTA %#x, dropped", val);
		isac->write_isac(isac, ISAC_CMDR, ISAC_CMDR_RMC);
		goto out;
	}

	count = isac->read_isac(isac, ISAC_RBCL) & 0x1f;
	DBG(DBG_IRQ, "RBCL %#x", count);
	if (count == 0)
		count = 0x20;

	isac_empty_fifo(isac, count);
	count = isac->rcvidx;
	if (count < 1) {
		DBG(DBG_WARN, "count %d < 1", count);
		goto out;
	}

	skb = alloc_skb(count, GFP_ATOMIC);
	if (!skb) {
		DBG(DBG_WARN, "no memory, dropping\n");
		goto out;
	}
	memcpy(skb_put(skb, count), isac->rcvbuf, count);
	DBG_SKB(DBG_RPACKET, skb);
	D_L1L2(isac, PH_DATA | INDICATION, skb);
out:
	isac->rcvidx = 0;
}

static inline void isac_xpr_interrupt(struct isac *isac)
{
	if (!isac->tx_skb)
		return;

	if (isac->tx_skb->len > 0) {
		isac_fill_fifo(isac);
		return;
	}
	dev_kfree_skb_irq(isac->tx_skb);
	isac->tx_cnt = 0;
	isac->tx_skb = NULL;
	D_L1L2(isac, PH_DATA | CONFIRM, NULL);
}

static inline void isac_exi_interrupt(struct isac *isac)
{
	unsigned char val;

	val = isac->read_isac(isac, ISAC_EXIR);
	DBG(2, "EXIR %#x", val);

	if (val & ISAC_EXIR_XMR) {
		DBG(DBG_WARN, "ISAC XMR");
		isac_retransmit(isac);
	}
	if (val & ISAC_EXIR_XDU) {
		DBG(DBG_WARN, "ISAC XDU");
		isac_retransmit(isac);
	}
	if (val & ISAC_EXIR_MOS) {  /* MOS */
		DBG(DBG_WARN, "MOS");
		val = isac->read_isac(isac, ISAC_MOSR);
		DBG(2, "ISAC MOSR %#x", val);
	}
}

void isac_irq(struct isac *isac)
{
	unsigned char val;

	val = isac->read_isac(isac, ISAC_ISTA);
	DBG(DBG_IRQ, "ISTA %#x", val);

	if (val & ISAC_ISTA_EXI) {
		DBG(DBG_IRQ, "EXI");
		isac_exi_interrupt(isac);
	}
	if (val & ISAC_ISTA_XPR) {
		DBG(DBG_IRQ, "XPR");
		isac_xpr_interrupt(isac);
	}
	if (val & ISAC_ISTA_RME) {
		DBG(DBG_IRQ, "RME");
		isac_rme_interrupt(isac);
	}
	if (val & ISAC_ISTA_RPF) {
		DBG(DBG_IRQ, "RPF");
		isac_empty_fifo(isac, 0x20);
	}
	if (val & ISAC_ISTA_CISQ) {
		DBG(DBG_IRQ, "CISQ");
		isac_cisq_interrupt(isac);
	}
	if (val & ISAC_ISTA_RSC) {
		DBG(DBG_WARN, "RSC");
	}
	if (val & ISAC_ISTA_SIN) {
		DBG(DBG_WARN, "SIN");
	}
	isac->write_isac(isac, ISAC_MASK, 0xff);
	isac->write_isac(isac, ISAC_MASK, 0x00);
}

// ======================================================================

static inline void isacsx_cic_interrupt(struct isac *isac)
{
	unsigned char val;

	val = isac->read_isac(isac, ISACSX_CIR0);
	DBG(DBG_IRQ, "CIR0 %#x", val);
	if (val & ISACSX_CIR0_CIC0) {
		DBG(DBG_IRQ, "CODR0 %#x", val >> 4);
		FsmEvent(&isac->l1m, val >> 4, NULL);
	}
}

static inline void isacsx_rme_interrupt(struct isac *isac)
{
	int count;
	struct sk_buff *skb;
	unsigned char val;

	val = isac->read_isac(isac, ISACSX_RSTAD);
	if ((val & (ISACSX_RSTAD_VFR |
		    ISACSX_RSTAD_RDO |
		    ISACSX_RSTAD_CRC |
		    ISACSX_RSTAD_RAB))
	    != (ISACSX_RSTAD_VFR | ISACSX_RSTAD_CRC)) {
		DBG(DBG_WARN, "RSTAD %#x, dropped", val);
		isac->write_isac(isac, ISACSX_CMDRD, ISACSX_CMDRD_RMC);
		goto out;
	}

	count = isac->read_isac(isac, ISACSX_RBCLD) & 0x1f;
	DBG(DBG_IRQ, "RBCLD %#x", count);
	if (count == 0)
		count = 0x20;

	isac_empty_fifo(isac, count);
	// strip trailing status byte
	count = isac->rcvidx - 1;
	if (count < 1) {
		DBG(DBG_WARN, "count %d < 1", count);
		goto out;
	}

	skb = dev_alloc_skb(count);
	if (!skb) {
		DBG(DBG_WARN, "no memory, dropping");
		goto out;
	}
	memcpy(skb_put(skb, count), isac->rcvbuf, count);
	DBG_SKB(DBG_RPACKET, skb);
	D_L1L2(isac, PH_DATA | INDICATION, skb);
out:
	isac->rcvidx = 0;
}

static inline void isacsx_xpr_interrupt(struct isac *isac)
{
	if (!isac->tx_skb)
		return;

	if (isac->tx_skb->len > 0) {
		isac_fill_fifo(isac);
		return;
	}
	dev_kfree_skb_irq(isac->tx_skb);
	isac->tx_skb = NULL;
	isac->tx_cnt = 0;
	D_L1L2(isac, PH_DATA | CONFIRM, NULL);
}

static inline void isacsx_icd_interrupt(struct isac *isac)
{
	unsigned char val;

	val = isac->read_isac(isac, ISACSX_ISTAD);
	DBG(DBG_IRQ, "ISTAD %#x", val);
	if (val & ISACSX_ISTAD_XDU) {
		DBG(DBG_WARN, "ISTAD XDU");
		isac_retransmit(isac);
	}
	if (val & ISACSX_ISTAD_XMR) {
		DBG(DBG_WARN, "ISTAD XMR");
		isac_retransmit(isac);
	}
	if (val & ISACSX_ISTAD_XPR) {
		DBG(DBG_IRQ, "ISTAD XPR");
		isacsx_xpr_interrupt(isac);
	}
	if (val & ISACSX_ISTAD_RFO) {
		DBG(DBG_WARN, "ISTAD RFO");
		isac->write_isac(isac, ISACSX_CMDRD, ISACSX_CMDRD_RMC);
	}
	if (val & ISACSX_ISTAD_RME) {
		DBG(DBG_IRQ, "ISTAD RME");
		isacsx_rme_interrupt(isac);
	}
	if (val & ISACSX_ISTAD_RPF) {
		DBG(DBG_IRQ, "ISTAD RPF");
		isac_empty_fifo(isac, 0x20);
	}
}

void isacsx_irq(struct isac *isac)
{
	unsigned char val;

	val = isac->read_isac(isac, ISACSX_ISTA);
	DBG(DBG_IRQ, "ISTA %#x", val);

	if (val & ISACSX_ISTA_ICD)
		isacsx_icd_interrupt(isac);
	if (val & ISACSX_ISTA_CIC)
		isacsx_cic_interrupt(isac);
}

void isac_init(struct isac *isac)
{
	isac->tx_skb = NULL;
	isac->l1m.fsm = &l1fsm;
	isac->l1m.state = ST_L1_RESET;
#ifdef CONFIG_HISAX_DEBUG
	isac->l1m.debug = 1;
#else
	isac->l1m.debug = 0;
#endif
	isac->l1m.userdata = isac;
	isac->l1m.printdebug = l1m_debug;
	FsmInitTimer(&isac->l1m, &isac->timer);
}

void isac_setup(struct isac *isac)
{
	int val, eval;

	isac->type = TYPE_ISAC;
	isac_version(isac);

	ph_command(isac, ISAC_CMD_RES);

	isac->write_isac(isac, ISAC_MASK, 0xff);
	isac->mocr = 0xaa;
	if (test_bit(ISAC_IOM1, &isac->flags)) {
		/* IOM 1 Mode */
		isac->write_isac(isac, ISAC_ADF2, 0x0);
		isac->write_isac(isac, ISAC_SPCR, 0xa);
		isac->write_isac(isac, ISAC_ADF1, 0x2);
		isac->write_isac(isac, ISAC_STCR, 0x70);
		isac->write_isac(isac, ISAC_MODE, 0xc9);
	} else {
		/* IOM 2 Mode */
		if (!isac->adf2)
			isac->adf2 = 0x80;
		isac->write_isac(isac, ISAC_ADF2, isac->adf2);
		isac->write_isac(isac, ISAC_SQXR, 0x2f);
		isac->write_isac(isac, ISAC_SPCR, 0x00);
		isac->write_isac(isac, ISAC_STCR, 0x70);
		isac->write_isac(isac, ISAC_MODE, 0xc9);
		isac->write_isac(isac, ISAC_TIMR, 0x00);
		isac->write_isac(isac, ISAC_ADF1, 0x00);
	}
	val = isac->read_isac(isac, ISAC_STAR);
	DBG(2, "ISAC STAR %x", val);
	val = isac->read_isac(isac, ISAC_MODE);
	DBG(2, "ISAC MODE %x", val);
	val = isac->read_isac(isac, ISAC_ADF2);
	DBG(2, "ISAC ADF2 %x", val);
	val = isac->read_isac(isac, ISAC_ISTA);
	DBG(2, "ISAC ISTA %x", val);
	if (val & 0x01) {
		eval = isac->read_isac(isac, ISAC_EXIR);
		DBG(2, "ISAC EXIR %x", eval);
	}
	val = isac->read_isac(isac, ISAC_CIR0);
	DBG(2, "ISAC CIR0 %x", val);
	FsmEvent(&isac->l1m, (val >> 2) & 0xf, NULL);

	isac->write_isac(isac, ISAC_MASK, 0x0);
	// RESET Receiver and Transmitter
	isac->write_isac(isac, ISAC_CMDR, ISAC_CMDR_XRES | ISAC_CMDR_RRES);
}

void isacsx_setup(struct isac *isac)
{
	isac->type = TYPE_ISACSX;
	// clear LDD
	isac->write_isac(isac, ISACSX_TR_CONF0, 0x00);
	// enable transmitter
	isac->write_isac(isac, ISACSX_TR_CONF2, 0x00);
	// transparent mode 0, RAC, stop/go
	isac->write_isac(isac, ISACSX_MODED,    0xc9);
	// all HDLC IRQ unmasked
	isac->write_isac(isac, ISACSX_MASKD,    0x03);
	// unmask ICD, CID IRQs
	isac->write_isac(isac, ISACSX_MASK,
			 ~(ISACSX_ISTA_ICD | ISACSX_ISTA_CIC));
}

void isac_d_l2l1(struct hisax_if *hisax_d_if, int pr, void *arg)
{
	struct isac *isac = hisax_d_if->priv;
	struct sk_buff *skb = arg;

	DBG(DBG_PR, "pr %#x", pr);

	switch (pr) {
	case PH_ACTIVATE | REQUEST:
		FsmEvent(&isac->l1m, EV_PH_ACTIVATE_REQ, NULL);
		break;
	case PH_DEACTIVATE | REQUEST:
		FsmEvent(&isac->l1m, EV_PH_DEACTIVATE_REQ, NULL);
		break;
	case PH_DATA | REQUEST:
		DBG(DBG_PR, "PH_DATA REQUEST len %d", skb->len);
		DBG_SKB(DBG_XPACKET, skb);
		if (isac->l1m.state != ST_L1_F7) {
			DBG(1, "L1 wrong state %d\n", isac->l1m.state);
			dev_kfree_skb(skb);
			break;
		}
		BUG_ON(isac->tx_skb);

		isac->tx_skb = skb;
		isac_fill_fifo(isac);
		break;
	}
}

static int __init hisax_isac_init(void)
{
	printk(KERN_INFO "hisax_isac: ISAC-S/ISAC-SX ISDN driver v0.1.0\n");

	l1fsm.state_count = L1_STATE_COUNT;
	l1fsm.event_count = L1_EVENT_COUNT;
	l1fsm.strState = strL1State;
	l1fsm.strEvent = strL1Event;
	return FsmNew(&l1fsm, L1FnList, ARRAY_SIZE(L1FnList));
}

static void __exit hisax_isac_exit(void)
{
	FsmFree(&l1fsm);
}

EXPORT_SYMBOL(isac_init);
EXPORT_SYMBOL(isac_d_l2l1);

EXPORT_SYMBOL(isacsx_setup);
EXPORT_SYMBOL(isacsx_irq);

EXPORT_SYMBOL(isac_setup);
EXPORT_SYMBOL(isac_irq);

module_init(hisax_isac_init);
module_exit(hisax_isac_exit);