Add mISDN DSP

Enable support for digital audio processing capability.
This module may be used for special applications that require
cross connecting of bchannels, conferencing, dtmf decoding
echo cancelation, tone generation, and Blowfish encryption and
decryption.
It may use hardware features if available.

Signed-off-by: Karsten Keil <kkeil@suse.de>

1 files changed, 1191 insertions, 0 deletions

diff --git a/drivers/isdn/mISDN/dsp_core.c b/drivers/isdn/mISDN/dsp_core.c
new file mode 100644
index 0000000..2f10ed8
--- /dev/null
+++ b/drivers/isdn/mISDN/dsp_core.c
@@ -0,0 +1,1191 @@
+/*
+ * Author       Andreas Eversberg (jolly@eversberg.eu)
+ * Based on source code structure by
+ *		Karsten Keil (keil@isdn4linux.de)
+ *
+ *		This file is (c) under GNU PUBLIC LICENSE
+ *		For changes and modifications please read
+ *		../../../Documentation/isdn/mISDN.cert
+ *
+ * Thanks to    Karsten Keil (great drivers)
+ *              Cologne Chip (great chips)
+ *
+ * This module does:
+ *		Real-time tone generation
+ *		DTMF detection
+ *		Real-time cross-connection and conferrence
+ *		Compensate jitter due to system load and hardware fault.
+ *		All features are done in kernel space and will be realized
+ *		using hardware, if available and supported by chip set.
+ *		Blowfish encryption/decryption
+ */
+
+/* STRUCTURE:
+ *
+ * The dsp module provides layer 2 for b-channels (64kbit). It provides
+ * transparent audio forwarding with special digital signal processing:
+ *
+ * - (1) generation of tones
+ * - (2) detection of dtmf tones
+ * - (3) crossconnecting and conferences (clocking)
+ * - (4) echo generation for delay test
+ * - (5) volume control
+ * - (6) disable receive data
+ * - (7) pipeline
+ * - (8) encryption/decryption
+ *
+ * Look:
+ *             TX            RX
+ *         ------upper layer------
+ *             |             ^
+ *             |             |(6)
+ *             v             |
+ *       +-----+-------------+-----+
+ *       |(3)(4)                   |
+ *       |           CMX           |
+ *       |                         |
+ *       |           +-------------+
+ *       |           |       ^
+ *       |           |       |
+ *       |+---------+|  +----+----+
+ *       ||(1)      ||  |(2)      |
+ *       ||         ||  |         |
+ *       ||  Tones  ||  |  DTMF   |
+ *       ||         ||  |         |
+ *       ||         ||  |         |
+ *       |+----+----+|  +----+----+
+ *       +-----+-----+       ^
+ *             |             |
+ *             v             |
+ *        +----+----+   +----+----+
+ *        |(5)      |   |(5)      |
+ *        |         |   |         |
+ *        |TX Volume|   |RX Volume|
+ *        |         |   |         |
+ *        |         |   |         |
+ *        +----+----+   +----+----+
+ *             |             ^
+ *             |             |
+ *             v             |
+ *        +----+-------------+----+
+ *        |(7)                    |
+ *        |                       |
+ *        |  Pipeline Processing  |
+ *        |                       |
+ *        |                       |
+ *        +----+-------------+----+
+ *             |             ^
+ *             |             |
+ *             v             |
+ *        +----+----+   +----+----+
+ *        |(8)      |   |(8)      |
+ *        |         |   |         |
+ *        | Encrypt |   | Decrypt |
+ *        |         |   |         |
+ *        |         |   |         |
+ *        +----+----+   +----+----+
+ *             |             ^
+ *             |             |
+ *             v             |
+ *         ------card  layer------
+ *             TX            RX
+ *
+ * Above you can see the logical data flow. If software is used to do the
+ * process, it is actually the real data flow. If hardware is used, data
+ * may not flow, but hardware commands to the card, to provide the data flow
+ * as shown.
+ *
+ * NOTE: The channel must be activated in order to make dsp work, even if
+ * no data flow to the upper layer is intended. Activation can be done
+ * after and before controlling the setting using PH_CONTROL requests.
+ *
+ * DTMF: Will be detected by hardware if possible. It is done before CMX
+ * processing.
+ *
+ * Tones: Will be generated via software if endless looped audio fifos are
+ * not supported by hardware. Tones will override all data from CMX.
+ * It is not required to join a conference to use tones at any time.
+ *
+ * CMX: Is transparent when not used. When it is used, it will do
+ * crossconnections and conferences via software if not possible through
+ * hardware. If hardware capability is available, hardware is used.
+ *
+ * Echo: Is generated by CMX and is used to check performane of hard and
+ * software CMX.
+ *
+ * The CMX has special functions for conferences with one, two and more
+ * members. It will allow different types of data flow. Receive and transmit
+ * data to/form upper layer may be swithed on/off individually without loosing
+ * features of CMX, Tones and DTMF.
+ *
+ * Echo Cancellation: Sometimes we like to cancel echo from the interface.
+ * Note that a VoIP call may not have echo caused by the IP phone. The echo
+ * is generated by the telephone line connected to it. Because the delay
+ * is high, it becomes an echo. RESULT: Echo Cachelation is required if
+ * both echo AND delay is applied to an interface.
+ * Remember that software CMX always generates a more or less delay.
+ *
+ * If all used features can be realized in hardware, and if transmit and/or
+ * receive data ist disabled, the card may not send/receive any data at all.
+ * Not receiving is usefull if only announcements are played. Not sending is
+ * usefull if an answering machine records audio. Not sending and receiving is
+ * usefull during most states of the call. If supported by hardware, tones
+ * will be played without cpu load. Small PBXs and NT-Mode applications will
+ * not need expensive hardware when processing calls.
+ *
+ *
+ * LOCKING:
+ *
+ * When data is received from upper or lower layer (card), the complete dsp
+ * module is locked by a global lock.  This lock MUST lock irq, because it
+ * must lock timer events by DSP poll timer.
+ * When data is ready to be transmitted down, the data is queued and sent
+ * outside lock and timer event.
+ * PH_CONTROL must not change any settings, join or split conference members
+ * during process of data.
+ *
+ * HDLC:
+ *
+ * It works quite the same as transparent, except that HDLC data is forwarded
+ * to all other conference members if no hardware bridging is possible.
+ * Send data will be writte to sendq. Sendq will be sent if confirm is received.
+ * Conference cannot join, if one member is not hdlc.
+ *
+ */
+
+#include <linux/delay.h>
+#include <linux/mISDNif.h>
+#include <linux/mISDNdsp.h>
+#include <linux/module.h>
+#include <linux/vmalloc.h>
+#include "core.h"
+#include "dsp.h"
+
+const char *mISDN_dsp_revision = "2.0";
+
+static int debug;
+static int options;
+static int poll;
+static int dtmfthreshold = 100;
+
+MODULE_AUTHOR("Andreas Eversberg");
+module_param(debug, uint, S_IRUGO | S_IWUSR);
+module_param(options, uint, S_IRUGO | S_IWUSR);
+module_param(poll, uint, S_IRUGO | S_IWUSR);
+module_param(dtmfthreshold, uint, S_IRUGO | S_IWUSR);
+MODULE_LICENSE("GPL");
+
+/*int spinnest = 0;*/
+
+spinlock_t dsp_lock; /* global dsp lock */
+struct list_head dsp_ilist;
+struct list_head conf_ilist;
+int dsp_debug;
+int dsp_options;
+int dsp_poll, dsp_tics;
+
+/* check if rx may be turned off or must be turned on */
+static void
+dsp_rx_off_member(struct dsp *dsp)
+{
+	struct mISDN_ctrl_req	cq;
+	int rx_off = 1;
+
+	if (!dsp->features_rx_off)
+		return;
+
+	/* not disabled */
+	if (!dsp->rx_disabled)
+		rx_off = 0;
+	/* software dtmf */
+	else if (dsp->dtmf.software)
+		rx_off = 0;
+	/* echo in software */
+	else if (dsp->echo && dsp->pcm_slot_tx < 0)
+		rx_off = 0;
+	/* bridge in software */
+	else if (dsp->conf) {
+		if (dsp->conf->software)
+			rx_off = 0;
+	}
+
+	if (rx_off == dsp->rx_is_off)
+		return;
+
+	if (!dsp->ch.peer) {
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: no peer, no rx_off\n",
+				__func__);
+		return;
+	}
+	cq.op = MISDN_CTRL_RX_OFF;
+	cq.p1 = rx_off;
+	if (dsp->ch.peer->ctrl(dsp->ch.peer, CONTROL_CHANNEL, &cq)) {
+		printk(KERN_DEBUG "%s: 2nd CONTROL_CHANNEL failed\n",
+			__func__);
+		return;
+	}
+	dsp->rx_is_off = rx_off;
+	if (dsp_debug & DEBUG_DSP_CORE)
+		printk(KERN_DEBUG "%s: %s set rx_off = %d\n",
+			__func__, dsp->name, rx_off);
+}
+static void
+dsp_rx_off(struct dsp *dsp)
+{
+	struct dsp_conf_member	*member;
+
+	if (dsp_options & DSP_OPT_NOHARDWARE)
+		return;
+
+	/* no conf */
+	if (!dsp->conf) {
+		dsp_rx_off_member(dsp);
+		return;
+	}
+	/* check all members in conf */
+	list_for_each_entry(member, &dsp->conf->mlist, list) {
+		dsp_rx_off_member(member->dsp);
+	}
+}
+
+static int
+dsp_control_req(struct dsp *dsp, struct mISDNhead *hh, struct sk_buff *skb)
+{
+	struct		sk_buff *nskb;
+	int ret = 0;
+	int cont;
+	u8 *data;
+	int len;
+
+	if (skb->len < sizeof(int))
+		printk(KERN_ERR "%s: PH_CONTROL message too short\n", __func__);
+	cont = *((int *)skb->data);
+	len = skb->len - sizeof(int);
+	data = skb->data + sizeof(int);
+
+	switch (cont) {
+	case DTMF_TONE_START: /* turn on DTMF */
+		if (dsp->hdlc) {
+			ret = -EINVAL;
+			break;
+		}
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: start dtmf\n", __func__);
+		if (len == sizeof(int)) {
+			printk(KERN_NOTICE "changing DTMF Threshold "
+				"to %d\n", *((int *)data));
+			dsp->dtmf.treshold = (*(int *)data) * 10000;
+		}
+		/* init goertzel */
+		dsp_dtmf_goertzel_init(dsp);
+
+		/* check dtmf hardware */
+		dsp_dtmf_hardware(dsp);
+		break;
+	case DTMF_TONE_STOP: /* turn off DTMF */
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: stop dtmf\n", __func__);
+		dsp->dtmf.hardware = 0;
+		dsp->dtmf.software = 0;
+		break;
+	case DSP_CONF_JOIN: /* join / update conference */
+		if (len < sizeof(int)) {
+			ret = -EINVAL;
+			break;
+		}
+		if (*((u32 *)data) == 0)
+			goto conf_split;
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: join conference %d\n",
+				__func__, *((u32 *)data));
+		ret = dsp_cmx_conf(dsp, *((u32 *)data));
+			/* dsp_cmx_hardware will also be called here */
+		dsp_rx_off(dsp);
+		if (dsp_debug & DEBUG_DSP_CMX)
+			dsp_cmx_debug(dsp);
+		break;
+	case DSP_CONF_SPLIT: /* remove from conference */
+conf_split:
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: release conference\n", __func__);
+		ret = dsp_cmx_conf(dsp, 0);
+			/* dsp_cmx_hardware will also be called here */
+		if (dsp_debug & DEBUG_DSP_CMX)
+			dsp_cmx_debug(dsp);
+		dsp_rx_off(dsp);
+		break;
+	case DSP_TONE_PATT_ON: /* play tone */
+		if (dsp->hdlc) {
+			ret = -EINVAL;
+			break;
+		}
+		if (len < sizeof(int)) {
+			ret = -EINVAL;
+			break;
+		}
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: turn tone 0x%x on\n",
+				__func__, *((int *)skb->data));
+		ret = dsp_tone(dsp, *((int *)data));
+		if (!ret) {
+			dsp_cmx_hardware(dsp->conf, dsp);
+			dsp_rx_off(dsp);
+		}
+		if (!dsp->tone.tone)
+			goto tone_off;
+		break;
+	case DSP_TONE_PATT_OFF: /* stop tone */
+		if (dsp->hdlc) {
+			ret = -EINVAL;
+			break;
+		}
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: turn tone off\n", __func__);
+		dsp_tone(dsp, 0);
+		dsp_cmx_hardware(dsp->conf, dsp);
+		dsp_rx_off(dsp);
+		/* reset tx buffers (user space data) */
+tone_off:
+		dsp->rx_W = 0;
+		dsp->rx_R = 0;
+		break;
+	case DSP_VOL_CHANGE_TX: /* change volume */
+		if (dsp->hdlc) {
+			ret = -EINVAL;
+			break;
+		}
+		if (len < sizeof(int)) {
+			ret = -EINVAL;
+			break;
+		}
+		dsp->tx_volume = *((int *)data);
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: change tx vol to %d\n",
+				__func__, dsp->tx_volume);
+		dsp_cmx_hardware(dsp->conf, dsp);
+		dsp_dtmf_hardware(dsp);
+		dsp_rx_off(dsp);
+		break;
+	case DSP_VOL_CHANGE_RX: /* change volume */
+		if (dsp->hdlc) {
+			ret = -EINVAL;
+			break;
+		}
+		if (len < sizeof(int)) {
+			ret = -EINVAL;
+			break;
+		}
+		dsp->rx_volume = *((int *)data);
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: change rx vol to %d\n",
+				__func__, dsp->tx_volume);
+		dsp_cmx_hardware(dsp->conf, dsp);
+		dsp_dtmf_hardware(dsp);
+		dsp_rx_off(dsp);
+		break;
+	case DSP_ECHO_ON: /* enable echo */
+		dsp->echo = 1; /* soft echo */
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: enable cmx-echo\n", __func__);
+		dsp_cmx_hardware(dsp->conf, dsp);
+		dsp_rx_off(dsp);
+		if (dsp_debug & DEBUG_DSP_CMX)
+			dsp_cmx_debug(dsp);
+		break;
+	case DSP_ECHO_OFF: /* disable echo */
+		dsp->echo = 0;
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: disable cmx-echo\n", __func__);
+		dsp_cmx_hardware(dsp->conf, dsp);
+		dsp_rx_off(dsp);
+		if (dsp_debug & DEBUG_DSP_CMX)
+			dsp_cmx_debug(dsp);
+		break;
+	case DSP_RECEIVE_ON: /* enable receive to user space */
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: enable receive to user "
+				"space\n", __func__);
+		dsp->rx_disabled = 0;
+		dsp_rx_off(dsp);
+		break;
+	case DSP_RECEIVE_OFF: /* disable receive to user space */
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: disable receive to "
+				"user space\n", __func__);
+		dsp->rx_disabled = 1;
+		dsp_rx_off(dsp);
+		break;
+	case DSP_MIX_ON: /* enable mixing of tx data */
+		if (dsp->hdlc) {
+			ret = -EINVAL;
+			break;
+		}
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: enable mixing of "
+				"tx-data with conf mebers\n", __func__);
+		dsp->tx_mix = 1;
+		dsp_cmx_hardware(dsp->conf, dsp);
+		dsp_rx_off(dsp);
+		if (dsp_debug & DEBUG_DSP_CMX)
+			dsp_cmx_debug(dsp);
+		break;
+	case DSP_MIX_OFF: /* disable mixing of tx data */
+		if (dsp->hdlc) {
+			ret = -EINVAL;
+			break;
+		}
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: disable mixing of "
+				"tx-data with conf mebers\n", __func__);
+		dsp->tx_mix = 0;
+		dsp_cmx_hardware(dsp->conf, dsp);
+		dsp_rx_off(dsp);
+		if (dsp_debug & DEBUG_DSP_CMX)
+			dsp_cmx_debug(dsp);
+		break;
+	case DSP_TXDATA_ON: /* enable txdata */
+		dsp->tx_data = 1;
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: enable tx-data\n", __func__);
+		dsp_cmx_hardware(dsp->conf, dsp);
+		dsp_rx_off(dsp);
+		if (dsp_debug & DEBUG_DSP_CMX)
+			dsp_cmx_debug(dsp);
+		break;
+	case DSP_TXDATA_OFF: /* disable txdata */
+		dsp->tx_data = 0;
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: disable tx-data\n", __func__);
+		dsp_cmx_hardware(dsp->conf, dsp);
+		dsp_rx_off(dsp);
+		if (dsp_debug & DEBUG_DSP_CMX)
+			dsp_cmx_debug(dsp);
+		break;
+	case DSP_DELAY: /* use delay algorithm instead of dynamic
+			   jitter algorithm */
+		if (dsp->hdlc) {
+			ret = -EINVAL;
+			break;
+		}
+		if (len < sizeof(int)) {
+			ret = -EINVAL;
+			break;
+		}
+		dsp->cmx_delay = (*((int *)data)) << 3;
+			/* miliseconds to samples */
+		if (dsp->cmx_delay >= (CMX_BUFF_HALF>>1))
+			/* clip to half of maximum usable buffer
+			(half of half buffer) */
+			dsp->cmx_delay = (CMX_BUFF_HALF>>1) - 1;
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: use delay algorithm to "
+				"compensate jitter (%d samples)\n",
+				__func__, dsp->cmx_delay);
+		break;
+	case DSP_JITTER: /* use dynamic jitter algorithm instead of
+		    delay algorithm */
+		if (dsp->hdlc) {
+			ret = -EINVAL;
+			break;
+		}
+		dsp->cmx_delay = 0;
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: use jitter algorithm to "
+				"compensate jitter\n", __func__);
+		break;
+	case DSP_TX_DEJITTER: /* use dynamic jitter algorithm for tx-buffer */
+		if (dsp->hdlc) {
+			ret = -EINVAL;
+			break;
+		}
+		dsp->tx_dejitter = 1;
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: use dejitter on TX "
+				"buffer\n", __func__);
+		break;
+	case DSP_TX_DEJ_OFF: /* use tx-buffer without dejittering*/
+		if (dsp->hdlc) {
+			ret = -EINVAL;
+			break;
+		}
+		dsp->tx_dejitter = 0;
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: use TX buffer without "
+				"dejittering\n", __func__);
+		break;
+	case DSP_PIPELINE_CFG:
+		if (dsp->hdlc) {
+			ret = -EINVAL;
+			break;
+		}
+		if (len > 0 && ((char *)data)[len - 1]) {
+			printk(KERN_DEBUG "%s: pipeline config string "
+				"is not NULL terminated!\n", __func__);
+			ret = -EINVAL;
+		} else {
+			dsp->pipeline.inuse = 1;
+			dsp_cmx_hardware(dsp->conf, dsp);
+			ret = dsp_pipeline_build(&dsp->pipeline,
+				len > 0 ? (char *)data : NULL);
+			dsp_cmx_hardware(dsp->conf, dsp);
+			dsp_rx_off(dsp);
+		}
+		break;
+	case DSP_BF_ENABLE_KEY: /* turn blowfish on */
+		if (dsp->hdlc) {
+			ret = -EINVAL;
+			break;
+		}
+		if (len < 4 || len > 56) {
+			ret = -EINVAL;
+			break;
+		}
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: turn blowfish on (key "
+				"not shown)\n", __func__);
+		ret = dsp_bf_init(dsp, (u8 *)data, len);
+		/* set new cont */
+		if (!ret)
+			cont = DSP_BF_ACCEPT;
+		else
+			cont = DSP_BF_REJECT;
+		/* send indication if it worked to set it */
+		nskb = _alloc_mISDN_skb(PH_CONTROL_IND, MISDN_ID_ANY,
+			sizeof(int), &cont, GFP_ATOMIC);
+		if (nskb) {
+			if (dsp->up) {
+				if (dsp->up->send(dsp->up, nskb))
+					dev_kfree_skb(nskb);
+			} else
+				dev_kfree_skb(nskb);
+		}
+		if (!ret) {
+			dsp_cmx_hardware(dsp->conf, dsp);
+			dsp_dtmf_hardware(dsp);
+			dsp_rx_off(dsp);
+		}
+		break;
+	case DSP_BF_DISABLE: /* turn blowfish off */
+		if (dsp->hdlc) {
+			ret = -EINVAL;
+			break;
+		}
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: turn blowfish off\n", __func__);
+		dsp_bf_cleanup(dsp);
+		dsp_cmx_hardware(dsp->conf, dsp);
+		dsp_dtmf_hardware(dsp);
+		dsp_rx_off(dsp);
+		break;
+	default:
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: ctrl req %x unhandled\n",
+				__func__, cont);
+		ret = -EINVAL;
+	}
+	return ret;
+}
+
+static void
+get_features(struct mISDNchannel *ch)
+{
+	struct dsp		*dsp = container_of(ch, struct dsp, ch);
+	struct mISDN_ctrl_req	cq;
+
+	if (dsp_options & DSP_OPT_NOHARDWARE)
+		return;
+	if (!ch->peer) {
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: no peer, no features\n",
+				__func__);
+		return;
+	}
+	memset(&cq, 0, sizeof(cq));
+	cq.op = MISDN_CTRL_GETOP;
+	if (ch->peer->ctrl(ch->peer, CONTROL_CHANNEL, &cq) < 0) {
+		printk(KERN_DEBUG "%s: CONTROL_CHANNEL failed\n",
+			__func__);
+		return;
+	}
+	if (cq.op & MISDN_CTRL_RX_OFF)
+		dsp->features_rx_off = 1;
+	if ((cq.op & MISDN_CTRL_HW_FEATURES_OP)) {
+		cq.op = MISDN_CTRL_HW_FEATURES;
+		*((u_long *)&cq.p1) = (u_long)&dsp->features;
+		if (ch->peer->ctrl(ch->peer, CONTROL_CHANNEL, &cq)) {
+			printk(KERN_DEBUG "%s: 2nd CONTROL_CHANNEL failed\n",
+				__func__);
+		}
+	} else
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: features not supported for %s\n",
+				__func__, dsp->name);
+}
+
+static int
+dsp_function(struct mISDNchannel *ch,  struct sk_buff *skb)
+{
+	struct dsp			*dsp = container_of(ch, struct dsp, ch);
+	struct mISDNhead	*hh;
+	int			ret = 0;
+	u8			*digits;
+	int			cont;
+	struct			sk_buff *nskb;
+	u_long			flags;
+
+	hh = mISDN_HEAD_P(skb);
+	switch (hh->prim) {
+	/* FROM DOWN */
+	case (PH_DATA_CNF):
+		dsp->data_pending = 0;
+		/* trigger next hdlc frame, if any */
+		if (dsp->hdlc) {
+			spin_lock_irqsave(&dsp_lock, flags);
+			if (dsp->b_active)
+				schedule_work(&dsp->workq);
+			spin_unlock_irqrestore(&dsp_lock, flags);
+		}
+		break;
+	case (PH_DATA_IND):
+	case (DL_DATA_IND):
+		if (skb->len < 1) {
+			ret = -EINVAL;
+			break;
+		}
+		if (dsp->rx_is_off) {
+			if (dsp_debug & DEBUG_DSP_CORE)
+				printk(KERN_DEBUG "%s: rx-data during rx_off"
+					" for %s\n",
+				__func__, dsp->name);
+		}
+		if (dsp->hdlc) {
+			/* hdlc */
+			spin_lock_irqsave(&dsp_lock, flags);
+			dsp_cmx_hdlc(dsp, skb);
+			spin_unlock_irqrestore(&dsp_lock, flags);
+			if (dsp->rx_disabled) {
+				/* if receive is not allowed */
+				break;
+			}
+			hh->prim = DL_DATA_IND;
+			if (dsp->up)
+				return dsp->up->send(dsp->up, skb);
+			break;
+		}
+
+		/* decrypt if enabled */
+		if (dsp->bf_enable)
+			dsp_bf_decrypt(dsp, skb->data, skb->len);
+		/* pipeline */
+		if (dsp->pipeline.inuse)
+			dsp_pipeline_process_rx(&dsp->pipeline, skb->data,
+				skb->len);
+		/* change volume if requested */
+		if (dsp->rx_volume)
+			dsp_change_volume(skb, dsp->rx_volume);
+
+		/* check if dtmf soft decoding is turned on */
+		if (dsp->dtmf.software) {
+			digits = dsp_dtmf_goertzel_decode(dsp, skb->data,
+				skb->len, (dsp_options&DSP_OPT_ULAW)?1:0);
+			while (*digits) {
+				if (dsp_debug & DEBUG_DSP_DTMF)
+					printk(KERN_DEBUG "%s: digit"
+					    "(%c) to layer %s\n",
+					    __func__, *digits, dsp->name);
+				cont = DTMF_TONE_VAL | *digits;
+				nskb = _alloc_mISDN_skb(PH_CONTROL_IND,
+				    MISDN_ID_ANY, sizeof(int), &cont,
+				    GFP_ATOMIC);
+				if (nskb) {
+					if (dsp->up) {
+						if (dsp->up->send(
+						    dsp->up, nskb))
+						dev_kfree_skb(nskb);
+					} else
+						dev_kfree_skb(nskb);
+				}
+				digits++;
+			}
+		}
+		/* we need to process receive data if software */
+		spin_lock_irqsave(&dsp_lock, flags);
+		if (dsp->pcm_slot_tx < 0 && dsp->pcm_slot_rx < 0) {
+			/* process data from card at cmx */
+			dsp_cmx_receive(dsp, skb);
+		}
+		spin_unlock_irqrestore(&dsp_lock, flags);
+
+		if (dsp->rx_disabled) {
+			/* if receive is not allowed */
+			break;
+		}
+		hh->prim = DL_DATA_IND;
+		if (dsp->up)
+			return dsp->up->send(dsp->up, skb);
+		break;
+	case (PH_CONTROL_IND):
+		if (dsp_debug & DEBUG_DSP_DTMFCOEFF)
+			printk(KERN_DEBUG "%s: PH_CONTROL INDICATION "
+				"received: %x (len %d) %s\n", __func__,
+				hh->id, skb->len, dsp->name);
+		switch (hh->id) {
+		case (DTMF_HFC_COEF): /* getting coefficients */
+			if (!dsp->dtmf.hardware) {
+				if (dsp_debug & DEBUG_DSP_DTMFCOEFF)
+					printk(KERN_DEBUG "%s: ignoring DTMF "
+						"coefficients from HFC\n",
+						__func__);
+				break;
+			}
+			digits = dsp_dtmf_goertzel_decode(dsp, skb->data,
+				skb->len, 2);
+			while (*digits) {
+				int k;
+				struct sk_buff *nskb;
+				if (dsp_debug & DEBUG_DSP_DTMF)
+					printk(KERN_DEBUG "%s: digit"
+					    "(%c) to layer %s\n",
+					    __func__, *digits, dsp->name);
+				k = *digits | DTMF_TONE_VAL;
+				nskb = _alloc_mISDN_skb(PH_CONTROL_IND,
+					MISDN_ID_ANY, sizeof(int), &k,
+					GFP_ATOMIC);
+				if (nskb) {
+					if (dsp->up) {
+						if (dsp->up->send(
+						    dsp->up, nskb))
+						dev_kfree_skb(nskb);
+					} else
+						dev_kfree_skb(nskb);
+				}
+				digits++;
+			}
+			break;
+		case (HFC_VOL_CHANGE_TX): /* change volume */
+			if (skb->len != sizeof(int)) {
+				ret = -EINVAL;
+				break;
+			}
+			spin_lock_irqsave(&dsp_lock, flags);
+			dsp->tx_volume = *((int *)skb->data);
+			if (dsp_debug & DEBUG_DSP_CORE)
+				printk(KERN_DEBUG "%s: change tx volume to "
+					"%d\n", __func__, dsp->tx_volume);
+			dsp_cmx_hardware(dsp->conf, dsp);
+			dsp_dtmf_hardware(dsp);
+			dsp_rx_off(dsp);
+			spin_unlock_irqrestore(&dsp_lock, flags);
+			break;
+		default:
+			if (dsp_debug & DEBUG_DSP_CORE)
+				printk(KERN_DEBUG "%s: ctrl ind %x unhandled "
+					"%s\n", __func__, hh->id, dsp->name);
+			ret = -EINVAL;
+		}
+		break;
+	case (PH_ACTIVATE_IND):
+	case (PH_ACTIVATE_CNF):
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: b_channel is now active %s\n",
+				__func__, dsp->name);
+		/* bchannel now active */
+		spin_lock_irqsave(&dsp_lock, flags);
+		dsp->b_active = 1;
+		dsp->data_pending = 0;
+		dsp->rx_init = 1;
+			/* rx_W and rx_R will be adjusted on first frame */
+		dsp->rx_W = 0;
+		dsp->rx_R = 0;
+		memset(dsp->rx_buff, 0, sizeof(dsp->rx_buff));
+		dsp_cmx_hardware(dsp->conf, dsp);
+		dsp_dtmf_hardware(dsp);
+		dsp_rx_off(dsp);
+		spin_unlock_irqrestore(&dsp_lock, flags);
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: done with activation, sending "
+				"confirm to user space. %s\n", __func__,
+				dsp->name);
+		/* send activation to upper layer */
+		hh->prim = DL_ESTABLISH_CNF;
+		if (dsp->up)
+			return dsp->up->send(dsp->up, skb);
+		break;
+	case (PH_DEACTIVATE_IND):
+	case (PH_DEACTIVATE_CNF):
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: b_channel is now inactive %s\n",
+				__func__, dsp->name);
+		/* bchannel now inactive */
+		spin_lock_irqsave(&dsp_lock, flags);
+		dsp->b_active = 0;
+		dsp->data_pending = 0;
+		dsp_cmx_hardware(dsp->conf, dsp);
+		dsp_rx_off(dsp);
+		spin_unlock_irqrestore(&dsp_lock, flags);
+		hh->prim = DL_RELEASE_CNF;
+		if (dsp->up)
+			return dsp->up->send(dsp->up, skb);
+		break;
+	/* FROM UP */
+	case (DL_DATA_REQ):
+	case (PH_DATA_REQ):
+		if (skb->len < 1) {
+			ret = -EINVAL;
+			break;
+		}
+		if (dsp->hdlc) {
+			/* hdlc */
+			spin_lock_irqsave(&dsp_lock, flags);
+			if (dsp->b_active) {
+				skb_queue_tail(&dsp->sendq, skb);
+				schedule_work(&dsp->workq);
+			}
+			spin_unlock_irqrestore(&dsp_lock, flags);
+			return 0;
+		}
+		/* send data to tx-buffer (if no tone is played) */
+		if (!dsp->tone.tone) {
+			spin_lock_irqsave(&dsp_lock, flags);
+			dsp_cmx_transmit(dsp, skb);
+			spin_unlock_irqrestore(&dsp_lock, flags);
+		}
+		break;
+	case (PH_CONTROL_REQ):
+		spin_lock_irqsave(&dsp_lock, flags);
+		ret = dsp_control_req(dsp, hh, skb);
+		spin_unlock_irqrestore(&dsp_lock, flags);
+		break;
+	case (DL_ESTABLISH_REQ):
+	case (PH_ACTIVATE_REQ):
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: activating b_channel %s\n",
+				__func__, dsp->name);
+		if (dsp->dtmf.hardware || dsp->dtmf.software)
+			dsp_dtmf_goertzel_init(dsp);
+		get_features(ch);
+		/* send ph_activate */
+		hh->prim = PH_ACTIVATE_REQ;
+		if (ch->peer)
+			return ch->recv(ch->peer, skb);
+		break;
+	case (DL_RELEASE_REQ):
+	case (PH_DEACTIVATE_REQ):
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: releasing b_channel %s\n",
+				__func__, dsp->name);
+		spin_lock_irqsave(&dsp_lock, flags);
+		dsp->tone.tone = 0;
+		dsp->tone.hardware = 0;
+		dsp->tone.software = 0;
+		if (timer_pending(&dsp->tone.tl))
+			del_timer(&dsp->tone.tl);
+		if (dsp->conf)
+			dsp_cmx_conf(dsp, 0); /* dsp_cmx_hardware will also be
+						 called here */
+		skb_queue_purge(&dsp->sendq);
+		spin_unlock_irqrestore(&dsp_lock, flags);
+		hh->prim = PH_DEACTIVATE_REQ;
+		if (ch->peer)
+			return ch->recv(ch->peer, skb);
+		break;
+	default:
+		if (dsp_debug & DEBUG_DSP_CORE)
+			printk(KERN_DEBUG "%s: msg %x unhandled %s\n",
+				__func__, hh->prim, dsp->name);
+		ret = -EINVAL;
+	}
+	if (!ret)
+		dev_kfree_skb(skb);
+	return ret;
+}
+
+static int
+dsp_ctrl(struct mISDNchannel *ch, u_int cmd, void *arg)
+{
+	struct dsp		*dsp = container_of(ch, struct dsp, ch);
+	u_long		flags;
+	int		err = 0;
+
+	if (debug & DEBUG_DSP_CTRL)
+	printk(KERN_DEBUG "%s:(%x)\n", __func__, cmd);
+
+	switch (cmd) {
+	case OPEN_CHANNEL:
+		break;
+	case CLOSE_CHANNEL:
+		if (dsp->ch.peer)
+			dsp->ch.peer->ctrl(dsp->ch.peer, CLOSE_CHANNEL, NULL);
+
+		/* wait until workqueue has finished,
+		 * must lock here, or we may hit send-process currently
+		 * queueing. */
+		spin_lock_irqsave(&dsp_lock, flags);
+		dsp->b_active = 0;
+		spin_unlock_irqrestore(&dsp_lock, flags);
+		/* MUST not be locked, because it waits until queue is done. */
+		cancel_work_sync(&dsp->workq);
+		spin_lock_irqsave(&dsp_lock, flags);
+		if (timer_pending(&dsp->tone.tl))
+			del_timer(&dsp->tone.tl);
+		skb_queue_purge(&dsp->sendq);
+		if (dsp_debug & DEBUG_DSP_CTRL)
+			printk(KERN_DEBUG "%s: releasing member %s\n",
+				__func__, dsp->name);
+		dsp->b_active = 0;
+		dsp_cmx_conf(dsp, 0); /* dsp_cmx_hardware will also be called
+					 here */
+		dsp_pipeline_destroy(&dsp->pipeline);
+
+		if (dsp_debug & DEBUG_DSP_CTRL)
+			printk(KERN_DEBUG "%s: remove & destroy object %s\n",
+				__func__, dsp->name);
+		list_del(&dsp->list);
+		spin_unlock_irqrestore(&dsp_lock, flags);
+
+		if (dsp_debug & DEBUG_DSP_CTRL)
+			printk(KERN_DEBUG "%s: dsp instance released\n",
+				__func__);
+		vfree(dsp);
+		module_put(THIS_MODULE);
+		break;
+	}
+	return err;
+}
+
+static void
+dsp_send_bh(struct work_struct *work)
+{
+	struct dsp *dsp = container_of(work, struct dsp, workq);
+	struct sk_buff *skb;
+	struct mISDNhead	*hh;
+
+	if (dsp->hdlc && dsp->data_pending)
+		return; /* wait until data has been acknowledged */
+
+	/* send queued data */
+	while ((skb = skb_dequeue(&dsp->sendq))) {
+		/* in locked date, we must have still data in queue */
+		if (dsp->data_pending) {
+			if (dsp_debug & DEBUG_DSP_CORE)
+				printk(KERN_DEBUG "%s: fifo full %s, this is "
+					"no bug!\n", __func__, dsp->name);
+			/* flush transparent data, if not acked */
+			dev_kfree_skb(skb);
+			continue;
+		}
+		hh = mISDN_HEAD_P(skb);
+		if (hh->prim == DL_DATA_REQ) {
+			/* send packet up */
+			if (dsp->up) {
+				if (dsp->up->send(dsp->up, skb))
+					dev_kfree_skb(skb);
+			} else
+				dev_kfree_skb(skb);
+		} else {
+			/* send packet down */
+			if (dsp->ch.peer) {
+				dsp->data_pending = 1;
+				if (dsp->ch.recv(dsp->ch.peer, skb)) {
+					dev_kfree_skb(skb);
+					dsp->data_pending = 0;
+				}
+			} else
+				dev_kfree_skb(skb);
+		}
+	}
+}
+
+static int
+dspcreate(struct channel_req *crq)
+{
+	struct dsp		*ndsp;
+	u_long		flags;
+
+	if (crq->protocol != ISDN_P_B_L2DSP
+	 && crq->protocol != ISDN_P_B_L2DSPHDLC)
+		return -EPROTONOSUPPORT;
+	ndsp = vmalloc(sizeof(struct dsp));
+	if (!ndsp) {
+		printk(KERN_ERR "%s: vmalloc struct dsp failed\n", __func__);
+		return -ENOMEM;
+	}
+	memset(ndsp, 0, sizeof(struct dsp));
+	if (dsp_debug & DEBUG_DSP_CTRL)
+		printk(KERN_DEBUG "%s: creating new dsp instance\n", __func__);
+
+	/* default enabled */
+	INIT_WORK(&ndsp->workq, (void *)dsp_send_bh);
+	skb_queue_head_init(&ndsp->sendq);
+	ndsp->ch.send = dsp_function;
+	ndsp->ch.ctrl = dsp_ctrl;
+	ndsp->up = crq->ch;
+	crq->ch = &ndsp->ch;
+	if (crq->protocol == ISDN_P_B_L2DSP) {
+		crq->protocol = ISDN_P_B_RAW;
+		ndsp->hdlc = 0;
+	} else {
+		crq->protocol = ISDN_P_B_HDLC;
+		ndsp->hdlc = 1;
+	}
+	if (!try_module_get(THIS_MODULE))
+		printk(KERN_WARNING "%s:cannot get module\n",
+			__func__);
+
+	sprintf(ndsp->name, "DSP_C%x(0x%p)",
+		ndsp->up->st->dev->id + 1, ndsp);
+	/* set frame size to start */
+	ndsp->features.hfc_id = -1; /* current PCM id */
+	ndsp->features.pcm_id = -1; /* current PCM id */
+	ndsp->pcm_slot_rx = -1; /* current CPM slot */
+	ndsp->pcm_slot_tx = -1;
+	ndsp->pcm_bank_rx = -1;
+	ndsp->pcm_bank_tx = -1;
+	ndsp->hfc_conf = -1; /* current conference number */
+	/* set tone timer */
+	ndsp->tone.tl.function = (void *)dsp_tone_timeout;
+	ndsp->tone.tl.data = (long) ndsp;
+	init_timer(&ndsp->tone.tl);
+
+	if (dtmfthreshold < 20 || dtmfthreshold > 500)
+		dtmfthreshold = 200;
+	ndsp->dtmf.treshold = dtmfthreshold*10000;
+
+	/* init pipeline append to list */
+	spin_lock_irqsave(&dsp_lock, flags);
+	dsp_pipeline_init(&ndsp->pipeline);
+	list_add_tail(&ndsp->list, &dsp_ilist);
+	spin_unlock_irqrestore(&dsp_lock, flags);
+
+	return 0;
+}
+
+
+static struct Bprotocol DSP = {
+	.Bprotocols = (1 << (ISDN_P_B_L2DSP & ISDN_P_B_MASK))
+		| (1 << (ISDN_P_B_L2DSPHDLC & ISDN_P_B_MASK)),
+	.name = "dsp",
+	.create = dspcreate
+};
+
+static int dsp_init(void)
+{
+	int err;
+	int tics;
+
+	printk(KERN_INFO "DSP modul %s\n", mISDN_dsp_revision);
+
+	dsp_options = options;
+	dsp_debug = debug;
+
+	/* set packet size */
+	dsp_poll = poll;
+	if (dsp_poll) {
+		if (dsp_poll > MAX_POLL) {
+			printk(KERN_ERR "%s: Wrong poll value (%d), use %d "
+				"maximum.\n", __func__, poll, MAX_POLL);
+			err = -EINVAL;
+			return err;
+		}
+		if (dsp_poll < 8) {
+			printk(KERN_ERR "%s: Wrong poll value (%d), use 8 "
+				"minimum.\n", __func__, dsp_poll);
+			err = -EINVAL;
+			return err;
+		}
+		dsp_tics = poll * HZ / 8000;
+		if (dsp_tics * 8000 != poll * HZ) {
+			printk(KERN_INFO "mISDN_dsp: Cannot clock every %d "
+				"samples (0,125 ms). It is not a multiple of "
+				"%d HZ.\n", poll, HZ);
+			err = -EINVAL;
+			return err;
+		}
+	} else {
+		poll = 8;
+		while (poll <= MAX_POLL) {
+			tics = poll * HZ / 8000;
+			if (tics * 8000 == poll * HZ) {
+				dsp_tics = tics;
+				dsp_poll = poll;
+				if (poll >= 64)
+					break;
+			}
+			poll++;
+		}
+	}
+	if (dsp_poll == 0) {
+		printk(KERN_INFO "mISDN_dsp: There is no multiple of kernel "
+			"clock that equals exactly the duration of 8-256 "
+			"samples. (Choose kernel clock speed like 100, 250, "
+			"300, 1000)\n");
+		err = -EINVAL;
+		return err;
+	}
+	printk(KERN_INFO "mISDN_dsp: DSP clocks every %d samples. This equals "
+		"%d jiffies.\n", dsp_poll, dsp_tics);
+
+	spin_lock_init(&dsp_lock);
+	INIT_LIST_HEAD(&dsp_ilist);
+	INIT_LIST_HEAD(&conf_ilist);
+
+	/* init conversion tables */
+	dsp_audio_generate_law_tables();
+	dsp_silence = (dsp_options&DSP_OPT_ULAW)?0xff:0x2a;
+	dsp_audio_law_to_s32 = (dsp_options&DSP_OPT_ULAW)?dsp_audio_ulaw_to_s32:
+		dsp_audio_alaw_to_s32;
+	dsp_audio_generate_s2law_table();
+	dsp_audio_generate_seven();
+	dsp_audio_generate_mix_table();
+	if (dsp_options & DSP_OPT_ULAW)
+		dsp_audio_generate_ulaw_samples();
+	dsp_audio_generate_volume_changes();
+
+	err = dsp_pipeline_module_init();
+	if (err) {
+		printk(KERN_ERR "mISDN_dsp: Can't initialize pipeline, "
+			"error(%d)\n", err);
+		return err;
+	}
+
+	err = mISDN_register_Bprotocol(&DSP);
+	if (err) {
+		printk(KERN_ERR "Can't register %s error(%d)\n", DSP.name, err);
+		return err;
+	}
+
+	/* set sample timer */
+	dsp_spl_tl.function = (void *)dsp_cmx_send;
+	dsp_spl_tl.data = 0;
+	init_timer(&dsp_spl_tl);
+	dsp_spl_tl.expires = jiffies + dsp_tics;
+	dsp_spl_jiffies = dsp_spl_tl.expires;
+	add_timer(&dsp_spl_tl);
+
+	return 0;
+}
+
+
+static void dsp_cleanup(void)
+{
+	mISDN_unregister_Bprotocol(&DSP);
+
+	if (timer_pending(&dsp_spl_tl))
+		del_timer(&dsp_spl_tl);
+
+	if (!list_empty(&dsp_ilist)) {
+		printk(KERN_ERR "mISDN_dsp: Audio DSP object inst list not "
+			"empty.\n");
+	}
+	if (!list_empty(&conf_ilist)) {
+		printk(KERN_ERR "mISDN_dsp: Conference list not empty. Not "
+			"all memory freed.\n");
+	}
+
+	dsp_pipeline_module_exit();
+}
+
+module_init(dsp_init);
+module_exit(dsp_cleanup);
+