treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

[mirror_ubuntu-focal-kernel.git] / drivers / isdn / gigaset / common.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Stuff used by all variants of the driver
 *
 * Copyright (c) 2001 by Stefan Eilers,
 *                       Hansjoerg Lipp <hjlipp@web.de>,
 *                       Tilman Schmidt <tilman@imap.cc>.
 *
 * =====================================================================
 * =====================================================================
 */

#include "gigaset.h"
#include <linux/module.h>
#include <linux/moduleparam.h>

/* Version Information */
#define DRIVER_AUTHOR "Hansjoerg Lipp <hjlipp@web.de>, Tilman Schmidt <tilman@imap.cc>, Stefan Eilers"
#define DRIVER_DESC "Driver for Gigaset 307x"

#ifdef CONFIG_GIGASET_DEBUG
#define DRIVER_DESC_DEBUG " (debug build)"
#else
#define DRIVER_DESC_DEBUG ""
#endif

/* Module parameters */
int gigaset_debuglevel;
EXPORT_SYMBOL_GPL(gigaset_debuglevel);
module_param_named(debug, gigaset_debuglevel, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "debug level");

/* driver state flags */
#define VALID_MINOR     0x01
#define VALID_ID        0x02

/**
 * gigaset_dbg_buffer() - dump data in ASCII and hex for debugging
 * @level:      debugging level.
 * @msg:        message prefix.
 * @len:        number of bytes to dump.
 * @buf:        data to dump.
 *
 * If the current debugging level includes one of the bits set in @level,
 * @len bytes starting at @buf are logged to dmesg at KERN_DEBUG prio,
 * prefixed by the text @msg.
 */
void gigaset_dbg_buffer(enum debuglevel level, const unsigned char *msg,
                        size_t len, const unsigned char *buf)
{
        unsigned char outbuf[80];
        unsigned char c;
        size_t space = sizeof outbuf - 1;
        unsigned char *out = outbuf;
        size_t numin = len;

        while (numin--) {
                c = *buf++;
                if (c == '~' || c == '^' || c == '\\') {
                        if (!space--)
                                break;
                        *out++ = '\\';
                }
                if (c & 0x80) {
                        if (!space--)
                                break;
                        *out++ = '~';
                        c ^= 0x80;
                }
                if (c < 0x20 || c == 0x7f) {
                        if (!space--)
                                break;
                        *out++ = '^';
                        c ^= 0x40;
                }
                if (!space--)
                        break;
                *out++ = c;
        }
        *out = 0;

        gig_dbg(level, "%s (%u bytes): %s", msg, (unsigned) len, outbuf);
}
EXPORT_SYMBOL_GPL(gigaset_dbg_buffer);

static int setflags(struct cardstate *cs, unsigned flags, unsigned delay)
{
        int r;

        r = cs->ops->set_modem_ctrl(cs, cs->control_state, flags);
        cs->control_state = flags;
        if (r < 0)
                return r;

        if (delay) {
                set_current_state(TASK_INTERRUPTIBLE);
                schedule_timeout(delay * HZ / 1000);
        }

        return 0;
}

int gigaset_enterconfigmode(struct cardstate *cs)
{
        int i, r;

        cs->control_state = TIOCM_RTS;

        r = setflags(cs, TIOCM_DTR, 200);
        if (r < 0)
                goto error;
        r = setflags(cs, 0, 200);
        if (r < 0)
                goto error;
        for (i = 0; i < 5; ++i) {
                r = setflags(cs, TIOCM_RTS, 100);
                if (r < 0)
                        goto error;
                r = setflags(cs, 0, 100);
                if (r < 0)
                        goto error;
        }
        r = setflags(cs, TIOCM_RTS | TIOCM_DTR, 800);
        if (r < 0)
                goto error;

        return 0;

error:
        dev_err(cs->dev, "error %d on setuartbits\n", -r);
        cs->control_state = TIOCM_RTS | TIOCM_DTR;
        cs->ops->set_modem_ctrl(cs, 0, TIOCM_RTS | TIOCM_DTR);

        return -1;
}

static int test_timeout(struct at_state_t *at_state)
{
        if (!at_state->timer_expires)
                return 0;

        if (--at_state->timer_expires) {
                gig_dbg(DEBUG_MCMD, "decreased timer of %p to %lu",
                        at_state, at_state->timer_expires);
                return 0;
        }

        gigaset_add_event(at_state->cs, at_state, EV_TIMEOUT, NULL,
                          at_state->timer_index, NULL);
        return 1;
}

static void timer_tick(struct timer_list *t)
{
        struct cardstate *cs = from_timer(cs, t, timer);
        unsigned long flags;
        unsigned channel;
        struct at_state_t *at_state;
        int timeout = 0;

        spin_lock_irqsave(&cs->lock, flags);

        for (channel = 0; channel < cs->channels; ++channel)
                if (test_timeout(&cs->bcs[channel].at_state))
                        timeout = 1;

        if (test_timeout(&cs->at_state))
                timeout = 1;

        list_for_each_entry(at_state, &cs->temp_at_states, list)
                if (test_timeout(at_state))
                        timeout = 1;

        if (cs->running) {
                mod_timer(&cs->timer, jiffies + msecs_to_jiffies(GIG_TICK));
                if (timeout) {
                        gig_dbg(DEBUG_EVENT, "scheduling timeout");
                        tasklet_schedule(&cs->event_tasklet);
                }
        }

        spin_unlock_irqrestore(&cs->lock, flags);
}

int gigaset_get_channel(struct bc_state *bcs)
{
        unsigned long flags;

        spin_lock_irqsave(&bcs->cs->lock, flags);
        if (bcs->use_count || !try_module_get(bcs->cs->driver->owner)) {
                gig_dbg(DEBUG_CHANNEL, "could not allocate channel %d",
                        bcs->channel);
                spin_unlock_irqrestore(&bcs->cs->lock, flags);
                return -EBUSY;
        }
        ++bcs->use_count;
        bcs->busy = 1;
        gig_dbg(DEBUG_CHANNEL, "allocated channel %d", bcs->channel);
        spin_unlock_irqrestore(&bcs->cs->lock, flags);
        return 0;
}

struct bc_state *gigaset_get_free_channel(struct cardstate *cs)
{
        unsigned long flags;
        int i;

        spin_lock_irqsave(&cs->lock, flags);
        if (!try_module_get(cs->driver->owner)) {
                gig_dbg(DEBUG_CHANNEL,
                        "could not get module for allocating channel");
                spin_unlock_irqrestore(&cs->lock, flags);
                return NULL;
        }
        for (i = 0; i < cs->channels; ++i)
                if (!cs->bcs[i].use_count) {
                        ++cs->bcs[i].use_count;
                        cs->bcs[i].busy = 1;
                        spin_unlock_irqrestore(&cs->lock, flags);
                        gig_dbg(DEBUG_CHANNEL, "allocated channel %d", i);
                        return cs->bcs + i;
                }
        module_put(cs->driver->owner);
        spin_unlock_irqrestore(&cs->lock, flags);
        gig_dbg(DEBUG_CHANNEL, "no free channel");
        return NULL;
}

void gigaset_free_channel(struct bc_state *bcs)
{
        unsigned long flags;

        spin_lock_irqsave(&bcs->cs->lock, flags);
        if (!bcs->busy) {
                gig_dbg(DEBUG_CHANNEL, "could not free channel %d",
                        bcs->channel);
                spin_unlock_irqrestore(&bcs->cs->lock, flags);
                return;
        }
        --bcs->use_count;
        bcs->busy = 0;
        module_put(bcs->cs->driver->owner);
        gig_dbg(DEBUG_CHANNEL, "freed channel %d", bcs->channel);
        spin_unlock_irqrestore(&bcs->cs->lock, flags);
}

int gigaset_get_channels(struct cardstate *cs)
{
        unsigned long flags;
        int i;

        spin_lock_irqsave(&cs->lock, flags);
        for (i = 0; i < cs->channels; ++i)
                if (cs->bcs[i].use_count) {
                        spin_unlock_irqrestore(&cs->lock, flags);
                        gig_dbg(DEBUG_CHANNEL,
                                "could not allocate all channels");
                        return -EBUSY;
                }
        for (i = 0; i < cs->channels; ++i)
                ++cs->bcs[i].use_count;
        spin_unlock_irqrestore(&cs->lock, flags);

        gig_dbg(DEBUG_CHANNEL, "allocated all channels");

        return 0;
}

void gigaset_free_channels(struct cardstate *cs)
{
        unsigned long flags;
        int i;

        gig_dbg(DEBUG_CHANNEL, "unblocking all channels");
        spin_lock_irqsave(&cs->lock, flags);
        for (i = 0; i < cs->channels; ++i)
                --cs->bcs[i].use_count;
        spin_unlock_irqrestore(&cs->lock, flags);
}

void gigaset_block_channels(struct cardstate *cs)
{
        unsigned long flags;
        int i;

        gig_dbg(DEBUG_CHANNEL, "blocking all channels");
        spin_lock_irqsave(&cs->lock, flags);
        for (i = 0; i < cs->channels; ++i)
                ++cs->bcs[i].use_count;
        spin_unlock_irqrestore(&cs->lock, flags);
}

static void clear_events(struct cardstate *cs)
{
        struct event_t *ev;
        unsigned head, tail;
        unsigned long flags;

        spin_lock_irqsave(&cs->ev_lock, flags);

        head = cs->ev_head;
        tail = cs->ev_tail;

        while (tail != head) {
                ev = cs->events + head;
                kfree(ev->ptr);
                head = (head + 1) % MAX_EVENTS;
        }

        cs->ev_head = tail;

        spin_unlock_irqrestore(&cs->ev_lock, flags);
}

/**
 * gigaset_add_event() - add event to device event queue
 * @cs:         device descriptor structure.
 * @at_state:   connection state structure.
 * @type:       event type.
 * @ptr:        pointer parameter for event.
 * @parameter:  integer parameter for event.
 * @arg:        pointer parameter for event.
 *
 * Allocate an event queue entry from the device's event queue, and set it up
 * with the parameters given.
 *
 * Return value: added event
 */
struct event_t *gigaset_add_event(struct cardstate *cs,
                                  struct at_state_t *at_state, int type,
                                  void *ptr, int parameter, void *arg)
{
        unsigned long flags;
        unsigned next, tail;
        struct event_t *event = NULL;

        gig_dbg(DEBUG_EVENT, "queueing event %d", type);

        spin_lock_irqsave(&cs->ev_lock, flags);

        tail = cs->ev_tail;
        next = (tail + 1) % MAX_EVENTS;
        if (unlikely(next == cs->ev_head))
                dev_err(cs->dev, "event queue full\n");
        else {
                event = cs->events + tail;
                event->type = type;
                event->at_state = at_state;
                event->cid = -1;
                event->ptr = ptr;
                event->arg = arg;
                event->parameter = parameter;
                cs->ev_tail = next;
        }

        spin_unlock_irqrestore(&cs->ev_lock, flags);

        return event;
}
EXPORT_SYMBOL_GPL(gigaset_add_event);

static void clear_at_state(struct at_state_t *at_state)
{
        int i;

        for (i = 0; i < STR_NUM; ++i) {
                kfree(at_state->str_var[i]);
                at_state->str_var[i] = NULL;
        }
}

static void dealloc_temp_at_states(struct cardstate *cs)
{
        struct at_state_t *cur, *next;

        list_for_each_entry_safe(cur, next, &cs->temp_at_states, list) {
                list_del(&cur->list);
                clear_at_state(cur);
                kfree(cur);
        }
}

static void gigaset_freebcs(struct bc_state *bcs)
{
        int i;

        gig_dbg(DEBUG_INIT, "freeing bcs[%d]->hw", bcs->channel);
        bcs->cs->ops->freebcshw(bcs);

        gig_dbg(DEBUG_INIT, "clearing bcs[%d]->at_state", bcs->channel);
        clear_at_state(&bcs->at_state);
        gig_dbg(DEBUG_INIT, "freeing bcs[%d]->skb", bcs->channel);
        dev_kfree_skb(bcs->rx_skb);
        bcs->rx_skb = NULL;

        for (i = 0; i < AT_NUM; ++i) {
                kfree(bcs->commands[i]);
                bcs->commands[i] = NULL;
        }
}

static struct cardstate *alloc_cs(struct gigaset_driver *drv)
{
        unsigned long flags;
        unsigned i;
        struct cardstate *cs;
        struct cardstate *ret = NULL;

        spin_lock_irqsave(&drv->lock, flags);
        if (drv->blocked)
                goto exit;
        for (i = 0; i < drv->minors; ++i) {
                cs = drv->cs + i;
                if (!(cs->flags & VALID_MINOR)) {
                        cs->flags = VALID_MINOR;
                        ret = cs;
                        break;
                }
        }
exit:
        spin_unlock_irqrestore(&drv->lock, flags);
        return ret;
}

static void free_cs(struct cardstate *cs)
{
        cs->flags = 0;
}

static void make_valid(struct cardstate *cs, unsigned mask)
{
        unsigned long flags;
        struct gigaset_driver *drv = cs->driver;
        spin_lock_irqsave(&drv->lock, flags);
        cs->flags |= mask;
        spin_unlock_irqrestore(&drv->lock, flags);
}

static void make_invalid(struct cardstate *cs, unsigned mask)
{
        unsigned long flags;
        struct gigaset_driver *drv = cs->driver;
        spin_lock_irqsave(&drv->lock, flags);
        cs->flags &= ~mask;
        spin_unlock_irqrestore(&drv->lock, flags);
}

/**
 * gigaset_freecs() - free all associated ressources of a device
 * @cs:         device descriptor structure.
 *
 * Stops all tasklets and timers, unregisters the device from all
 * subsystems it was registered to, deallocates the device structure
 * @cs and all structures referenced from it.
 * Operations on the device should be stopped before calling this.
 */
void gigaset_freecs(struct cardstate *cs)
{
        int i;
        unsigned long flags;

        if (!cs)
                return;

        mutex_lock(&cs->mutex);

        spin_lock_irqsave(&cs->lock, flags);
        cs->running = 0;
        spin_unlock_irqrestore(&cs->lock, flags); /* event handler and timer are
                                                     not rescheduled below */

        tasklet_kill(&cs->event_tasklet);
        del_timer_sync(&cs->timer);

        switch (cs->cs_init) {
        default:
                /* clear B channel structures */
                for (i = 0; i < cs->channels; ++i) {
                        gig_dbg(DEBUG_INIT, "clearing bcs[%d]", i);
                        gigaset_freebcs(cs->bcs + i);
                }

                /* clear device sysfs */
                gigaset_free_dev_sysfs(cs);

                gigaset_if_free(cs);

                gig_dbg(DEBUG_INIT, "clearing hw");
                cs->ops->freecshw(cs);

                /* fall through */
        case 2: /* error in initcshw */
                /* Deregister from LL */
                make_invalid(cs, VALID_ID);
                gigaset_isdn_unregdev(cs);

                /* fall through */
        case 1: /* error when registering to LL */
                gig_dbg(DEBUG_INIT, "clearing at_state");
                clear_at_state(&cs->at_state);
                dealloc_temp_at_states(cs);
                clear_events(cs);
                tty_port_destroy(&cs->port);

                /* fall through */
        case 0: /* error in basic setup */
                gig_dbg(DEBUG_INIT, "freeing inbuf");
                kfree(cs->inbuf);
                kfree(cs->bcs);
        }

        mutex_unlock(&cs->mutex);
        free_cs(cs);
}
EXPORT_SYMBOL_GPL(gigaset_freecs);

void gigaset_at_init(struct at_state_t *at_state, struct bc_state *bcs,
                     struct cardstate *cs, int cid)
{
        int i;

        INIT_LIST_HEAD(&at_state->list);
        at_state->waiting = 0;
        at_state->getstring = 0;
        at_state->pending_commands = 0;
        at_state->timer_expires = 0;
        at_state->timer_active = 0;
        at_state->timer_index = 0;
        at_state->seq_index = 0;
        at_state->ConState = 0;
        for (i = 0; i < STR_NUM; ++i)
                at_state->str_var[i] = NULL;
        at_state->int_var[VAR_ZDLE] = 0;
        at_state->int_var[VAR_ZCTP] = -1;
        at_state->int_var[VAR_ZSAU] = ZSAU_NULL;
        at_state->cs = cs;
        at_state->bcs = bcs;
        at_state->cid = cid;
        if (!cid)
                at_state->replystruct = cs->tabnocid;
        else
                at_state->replystruct = cs->tabcid;
}


static void gigaset_inbuf_init(struct inbuf_t *inbuf, struct cardstate *cs)
/* inbuf->read must be allocated before! */
{
        inbuf->head = 0;
        inbuf->tail = 0;
        inbuf->cs = cs;
        inbuf->inputstate = INS_command;
}

/**
 * gigaset_fill_inbuf() - append received data to input buffer
 * @inbuf:      buffer structure.
 * @src:        received data.
 * @numbytes:   number of bytes received.
 *
 * Return value: !=0 if some data was appended
 */
int gigaset_fill_inbuf(struct inbuf_t *inbuf, const unsigned char *src,
                       unsigned numbytes)
{
        unsigned n, head, tail, bytesleft;

        gig_dbg(DEBUG_INTR, "received %u bytes", numbytes);

        if (!numbytes)
                return 0;

        bytesleft = numbytes;
        tail = inbuf->tail;
        head = inbuf->head;
        gig_dbg(DEBUG_INTR, "buffer state: %u -> %u", head, tail);

        while (bytesleft) {
                if (head > tail)
                        n = head - 1 - tail;
                else if (head == 0)
                        n = (RBUFSIZE - 1) - tail;
                else
                        n = RBUFSIZE - tail;
                if (!n) {
                        dev_err(inbuf->cs->dev,
                                "buffer overflow (%u bytes lost)\n",
                                bytesleft);
                        break;
                }
                if (n > bytesleft)
                        n = bytesleft;
                memcpy(inbuf->data + tail, src, n);
                bytesleft -= n;
                tail = (tail + n) % RBUFSIZE;
                src += n;
        }
        gig_dbg(DEBUG_INTR, "setting tail to %u", tail);
        inbuf->tail = tail;
        return numbytes != bytesleft;
}
EXPORT_SYMBOL_GPL(gigaset_fill_inbuf);

/* Initialize the b-channel structure */
static int gigaset_initbcs(struct bc_state *bcs, struct cardstate *cs,
                           int channel)
{
        int i;

        bcs->tx_skb = NULL;

        skb_queue_head_init(&bcs->squeue);

        bcs->corrupted = 0;
        bcs->trans_down = 0;
        bcs->trans_up = 0;

        gig_dbg(DEBUG_INIT, "setting up bcs[%d]->at_state", channel);
        gigaset_at_init(&bcs->at_state, bcs, cs, -1);

#ifdef CONFIG_GIGASET_DEBUG
        bcs->emptycount = 0;
#endif

        bcs->rx_bufsize = 0;
        bcs->rx_skb = NULL;
        bcs->rx_fcs = PPP_INITFCS;
        bcs->inputstate = 0;
        bcs->channel = channel;
        bcs->cs = cs;

        bcs->chstate = 0;
        bcs->use_count = 1;
        bcs->busy = 0;
        bcs->ignore = cs->ignoreframes;

        for (i = 0; i < AT_NUM; ++i)
                bcs->commands[i] = NULL;

        spin_lock_init(&bcs->aplock);
        bcs->ap = NULL;
        bcs->apconnstate = 0;

        gig_dbg(DEBUG_INIT, "  setting up bcs[%d]->hw", channel);
        return cs->ops->initbcshw(bcs);
}

/**
 * gigaset_initcs() - initialize device structure
 * @drv:        hardware driver the device belongs to
 * @channels:   number of B channels supported by device
 * @onechannel: !=0 if B channel data and AT commands share one
 *                  communication channel (M10x),
 *              ==0 if B channels have separate communication channels (base)
 * @ignoreframes:       number of frames to ignore after setting up B channel
 * @cidmode:    !=0: start in CallID mode
 * @modulename: name of driver module for LL registration
 *
 * Allocate and initialize cardstate structure for Gigaset driver
 * Calls hardware dependent gigaset_initcshw() function
 * Calls B channel initialization function gigaset_initbcs() for each B channel
 *
 * Return value:
 *      pointer to cardstate structure
 */
struct cardstate *gigaset_initcs(struct gigaset_driver *drv, int channels,
                                 int onechannel, int ignoreframes,
                                 int cidmode, const char *modulename)
{
        struct cardstate *cs;
        unsigned long flags;
        int i;

        gig_dbg(DEBUG_INIT, "allocating cs");
        cs = alloc_cs(drv);
        if (!cs) {
                pr_err("maximum number of devices exceeded\n");
                return NULL;
        }

        cs->cs_init = 0;
        cs->channels = channels;
        cs->onechannel = onechannel;
        cs->ignoreframes = ignoreframes;
        INIT_LIST_HEAD(&cs->temp_at_states);
        cs->running = 0;
        timer_setup(&cs->timer, timer_tick, 0);
        spin_lock_init(&cs->ev_lock);
        cs->ev_tail = 0;
        cs->ev_head = 0;

        tasklet_init(&cs->event_tasklet, gigaset_handle_event,
                     (unsigned long) cs);
        tty_port_init(&cs->port);
        cs->commands_pending = 0;
        cs->cur_at_seq = 0;
        cs->gotfwver = -1;
        cs->dev = NULL;
        cs->tty_dev = NULL;
        cs->cidmode = cidmode != 0;
        cs->tabnocid = gigaset_tab_nocid;
        cs->tabcid = gigaset_tab_cid;

        init_waitqueue_head(&cs->waitqueue);
        cs->waiting = 0;

        cs->mode = M_UNKNOWN;
        cs->mstate = MS_UNINITIALIZED;

        cs->bcs = kmalloc_array(channels, sizeof(struct bc_state), GFP_KERNEL);
        cs->inbuf = kmalloc(sizeof(struct inbuf_t), GFP_KERNEL);
        if (!cs->bcs || !cs->inbuf) {
                pr_err("out of memory\n");
                goto error;
        }
        ++cs->cs_init;

        gig_dbg(DEBUG_INIT, "setting up at_state");
        spin_lock_init(&cs->lock);
        gigaset_at_init(&cs->at_state, NULL, cs, 0);
        cs->dle = 0;
        cs->cbytes = 0;

        gig_dbg(DEBUG_INIT, "setting up inbuf");
        gigaset_inbuf_init(cs->inbuf, cs);

        cs->connected = 0;
        cs->isdn_up = 0;

        gig_dbg(DEBUG_INIT, "setting up cmdbuf");
        cs->cmdbuf = cs->lastcmdbuf = NULL;
        spin_lock_init(&cs->cmdlock);
        cs->curlen = 0;
        cs->cmdbytes = 0;

        gig_dbg(DEBUG_INIT, "setting up iif");
        if (gigaset_isdn_regdev(cs, modulename) < 0) {
                pr_err("error registering ISDN device\n");
                goto error;
        }

        make_valid(cs, VALID_ID);
        ++cs->cs_init;
        gig_dbg(DEBUG_INIT, "setting up hw");
        if (cs->ops->initcshw(cs) < 0)
                goto error;

        ++cs->cs_init;

        /* set up character device */
        gigaset_if_init(cs);

        /* set up device sysfs */
        gigaset_init_dev_sysfs(cs);

        /* set up channel data structures */
        for (i = 0; i < channels; ++i) {
                gig_dbg(DEBUG_INIT, "setting up bcs[%d]", i);
                if (gigaset_initbcs(cs->bcs + i, cs, i) < 0) {
                        pr_err("could not allocate channel %d data\n", i);
                        goto error;
                }
        }

        spin_lock_irqsave(&cs->lock, flags);
        cs->running = 1;
        spin_unlock_irqrestore(&cs->lock, flags);
        cs->timer.expires = jiffies + msecs_to_jiffies(GIG_TICK);
        add_timer(&cs->timer);

        gig_dbg(DEBUG_INIT, "cs initialized");
        return cs;

error:
        gig_dbg(DEBUG_INIT, "failed");
        gigaset_freecs(cs);
        return NULL;
}
EXPORT_SYMBOL_GPL(gigaset_initcs);

/* ReInitialize the b-channel structure on hangup */
void gigaset_bcs_reinit(struct bc_state *bcs)
{
        struct sk_buff *skb;
        struct cardstate *cs = bcs->cs;
        unsigned long flags;

        while ((skb = skb_dequeue(&bcs->squeue)) != NULL)
                dev_kfree_skb(skb);

        spin_lock_irqsave(&cs->lock, flags);
        clear_at_state(&bcs->at_state);
        bcs->at_state.ConState = 0;
        bcs->at_state.timer_active = 0;
        bcs->at_state.timer_expires = 0;
        bcs->at_state.cid = -1;                 /* No CID defined */
        spin_unlock_irqrestore(&cs->lock, flags);

        bcs->inputstate = 0;

#ifdef CONFIG_GIGASET_DEBUG
        bcs->emptycount = 0;
#endif

        bcs->rx_fcs = PPP_INITFCS;
        bcs->chstate = 0;

        bcs->ignore = cs->ignoreframes;
        dev_kfree_skb(bcs->rx_skb);
        bcs->rx_skb = NULL;

        cs->ops->reinitbcshw(bcs);
}

static void cleanup_cs(struct cardstate *cs)
{
        struct cmdbuf_t *cb, *tcb;
        int i;
        unsigned long flags;

        spin_lock_irqsave(&cs->lock, flags);

        cs->mode = M_UNKNOWN;
        cs->mstate = MS_UNINITIALIZED;

        clear_at_state(&cs->at_state);
        dealloc_temp_at_states(cs);
        gigaset_at_init(&cs->at_state, NULL, cs, 0);

        cs->inbuf->inputstate = INS_command;
        cs->inbuf->head = 0;
        cs->inbuf->tail = 0;

        cb = cs->cmdbuf;
        while (cb) {
                tcb = cb;
                cb = cb->next;
                kfree(tcb);
        }
        cs->cmdbuf = cs->lastcmdbuf = NULL;
        cs->curlen = 0;
        cs->cmdbytes = 0;
        cs->gotfwver = -1;
        cs->dle = 0;
        cs->cur_at_seq = 0;
        cs->commands_pending = 0;
        cs->cbytes = 0;

        spin_unlock_irqrestore(&cs->lock, flags);

        for (i = 0; i < cs->channels; ++i) {
                gigaset_freebcs(cs->bcs + i);
                if (gigaset_initbcs(cs->bcs + i, cs, i) < 0)
                        pr_err("could not allocate channel %d data\n", i);
        }

        if (cs->waiting) {
                cs->cmd_result = -ENODEV;
                cs->waiting = 0;
                wake_up_interruptible(&cs->waitqueue);
        }
}


/**
 * gigaset_start() - start device operations
 * @cs:         device descriptor structure.
 *
 * Prepares the device for use by setting up communication parameters,
 * scheduling an EV_START event to initiate device initialization, and
 * waiting for completion of the initialization.
 *
 * Return value:
 *      0 on success, error code < 0 on failure
 */
int gigaset_start(struct cardstate *cs)
{
        unsigned long flags;

        if (mutex_lock_interruptible(&cs->mutex))
                return -EBUSY;

        spin_lock_irqsave(&cs->lock, flags);
        cs->connected = 1;
        spin_unlock_irqrestore(&cs->lock, flags);

        if (cs->mstate != MS_LOCKED) {
                cs->ops->set_modem_ctrl(cs, 0, TIOCM_DTR | TIOCM_RTS);
                cs->ops->baud_rate(cs, B115200);
                cs->ops->set_line_ctrl(cs, CS8);
                cs->control_state = TIOCM_DTR | TIOCM_RTS;
        }

        cs->waiting = 1;

        if (!gigaset_add_event(cs, &cs->at_state, EV_START, NULL, 0, NULL)) {
                cs->waiting = 0;
                goto error;
        }
        gigaset_schedule_event(cs);

        wait_event(cs->waitqueue, !cs->waiting);

        mutex_unlock(&cs->mutex);
        return 0;

error:
        mutex_unlock(&cs->mutex);
        return -ENOMEM;
}
EXPORT_SYMBOL_GPL(gigaset_start);

/**
 * gigaset_shutdown() - shut down device operations
 * @cs:         device descriptor structure.
 *
 * Deactivates the device by scheduling an EV_SHUTDOWN event and
 * waiting for completion of the shutdown.
 *
 * Return value:
 *      0 - success, -ENODEV - error (no device associated)
 */
int gigaset_shutdown(struct cardstate *cs)
{
        mutex_lock(&cs->mutex);

        if (!(cs->flags & VALID_MINOR)) {
                mutex_unlock(&cs->mutex);
                return -ENODEV;
        }

        cs->waiting = 1;

        if (!gigaset_add_event(cs, &cs->at_state, EV_SHUTDOWN, NULL, 0, NULL))
                goto exit;
        gigaset_schedule_event(cs);

        wait_event(cs->waitqueue, !cs->waiting);

        cleanup_cs(cs);

exit:
        mutex_unlock(&cs->mutex);
        return 0;
}
EXPORT_SYMBOL_GPL(gigaset_shutdown);

/**
 * gigaset_stop() - stop device operations
 * @cs:         device descriptor structure.
 *
 * Stops operations on the device by scheduling an EV_STOP event and
 * waiting for completion of the shutdown.
 */
void gigaset_stop(struct cardstate *cs)
{
        mutex_lock(&cs->mutex);

        cs->waiting = 1;

        if (!gigaset_add_event(cs, &cs->at_state, EV_STOP, NULL, 0, NULL))
                goto exit;
        gigaset_schedule_event(cs);

        wait_event(cs->waitqueue, !cs->waiting);

        cleanup_cs(cs);

exit:
        mutex_unlock(&cs->mutex);
}
EXPORT_SYMBOL_GPL(gigaset_stop);

static LIST_HEAD(drivers);
static DEFINE_SPINLOCK(driver_lock);

struct cardstate *gigaset_get_cs_by_id(int id)
{
        unsigned long flags;
        struct cardstate *ret = NULL;
        struct cardstate *cs;
        struct gigaset_driver *drv;
        unsigned i;

        spin_lock_irqsave(&driver_lock, flags);
        list_for_each_entry(drv, &drivers, list) {
                spin_lock(&drv->lock);
                for (i = 0; i < drv->minors; ++i) {
                        cs = drv->cs + i;
                        if ((cs->flags & VALID_ID) && cs->myid == id) {
                                ret = cs;
                                break;
                        }
                }
                spin_unlock(&drv->lock);
                if (ret)
                        break;
        }
        spin_unlock_irqrestore(&driver_lock, flags);
        return ret;
}

static struct cardstate *gigaset_get_cs_by_minor(unsigned minor)
{
        unsigned long flags;
        struct cardstate *ret = NULL;
        struct gigaset_driver *drv;
        unsigned index;

        spin_lock_irqsave(&driver_lock, flags);
        list_for_each_entry(drv, &drivers, list) {
                if (minor < drv->minor || minor >= drv->minor + drv->minors)
                        continue;
                index = minor - drv->minor;
                spin_lock(&drv->lock);
                if (drv->cs[index].flags & VALID_MINOR)
                        ret = drv->cs + index;
                spin_unlock(&drv->lock);
                if (ret)
                        break;
        }
        spin_unlock_irqrestore(&driver_lock, flags);
        return ret;
}

struct cardstate *gigaset_get_cs_by_tty(struct tty_struct *tty)
{
        return gigaset_get_cs_by_minor(tty->index + tty->driver->minor_start);
}

/**
 * gigaset_freedriver() - free all associated ressources of a driver
 * @drv:        driver descriptor structure.
 *
 * Unregisters the driver from the system and deallocates the driver
 * structure @drv and all structures referenced from it.
 * All devices should be shut down before calling this.
 */
void gigaset_freedriver(struct gigaset_driver *drv)
{
        unsigned long flags;

        spin_lock_irqsave(&driver_lock, flags);
        list_del(&drv->list);
        spin_unlock_irqrestore(&driver_lock, flags);

        gigaset_if_freedriver(drv);

        kfree(drv->cs);
        kfree(drv);
}
EXPORT_SYMBOL_GPL(gigaset_freedriver);

/**
 * gigaset_initdriver() - initialize driver structure
 * @minor:      First minor number
 * @minors:     Number of minors this driver can handle
 * @procname:   Name of the driver
 * @devname:    Name of the device files (prefix without minor number)
 *
 * Allocate and initialize gigaset_driver structure. Initialize interface.
 *
 * Return value:
 *      Pointer to the gigaset_driver structure on success, NULL on failure.
 */
struct gigaset_driver *gigaset_initdriver(unsigned minor, unsigned minors,
                                          const char *procname,
                                          const char *devname,
                                          const struct gigaset_ops *ops,
                                          struct module *owner)
{
        struct gigaset_driver *drv;
        unsigned long flags;
        unsigned i;

        drv = kmalloc(sizeof *drv, GFP_KERNEL);
        if (!drv)
                return NULL;

        drv->have_tty = 0;
        drv->minor = minor;
        drv->minors = minors;
        spin_lock_init(&drv->lock);
        drv->blocked = 0;
        drv->ops = ops;
        drv->owner = owner;
        INIT_LIST_HEAD(&drv->list);

        drv->cs = kmalloc_array(minors, sizeof(*drv->cs), GFP_KERNEL);
        if (!drv->cs)
                goto error;

        for (i = 0; i < minors; ++i) {
                drv->cs[i].flags = 0;
                drv->cs[i].driver = drv;
                drv->cs[i].ops = drv->ops;
                drv->cs[i].minor_index = i;
                mutex_init(&drv->cs[i].mutex);
        }

        gigaset_if_initdriver(drv, procname, devname);

        spin_lock_irqsave(&driver_lock, flags);
        list_add(&drv->list, &drivers);
        spin_unlock_irqrestore(&driver_lock, flags);

        return drv;

error:
        kfree(drv);
        return NULL;
}
EXPORT_SYMBOL_GPL(gigaset_initdriver);

/**
 * gigaset_blockdriver() - block driver
 * @drv:        driver descriptor structure.
 *
 * Prevents the driver from attaching new devices, in preparation for
 * deregistration.
 */
void gigaset_blockdriver(struct gigaset_driver *drv)
{
        drv->blocked = 1;
}
EXPORT_SYMBOL_GPL(gigaset_blockdriver);

static int __init gigaset_init_module(void)
{
        /* in accordance with the principle of least astonishment,
         * setting the 'debug' parameter to 1 activates a sensible
         * set of default debug levels
         */
        if (gigaset_debuglevel == 1)
                gigaset_debuglevel = DEBUG_DEFAULT;

        pr_info(DRIVER_DESC DRIVER_DESC_DEBUG "\n");
        gigaset_isdn_regdrv();
        return 0;
}

static void __exit gigaset_exit_module(void)
{
        gigaset_isdn_unregdrv();
}

module_init(gigaset_init_module);
module_exit(gigaset_exit_module);

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);

MODULE_LICENSE("GPL");