Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1949 insertions, 0 deletions

diff --git a/drivers/isdn/mISDN/dsp_cmx.c b/drivers/isdn/mISDN/dsp_cmx.c
new file mode 100644
index 0000000000..61cb45c5d0
--- /dev/null
+++ b/drivers/isdn/mISDN/dsp_cmx.c
@@ -0,0 +1,1949 @@
+/*
+ * Audio crossconnecting/conferrencing (hardware level).
+ *
+ * Copyright 2002 by Andreas Eversberg (jolly@eversberg.eu)
+ *
+ * This software may be used and distributed according to the terms
+ * of the GNU General Public License, incorporated herein by reference.
+ *
+ */
+
+/*
+ * The process of adding and removing parties to/from a conference:
+ *
+ * There is a chain of struct dsp_conf which has one or more members in a chain
+ * of struct dsp_conf_member.
+ *
+ * After a party is added, the conference is checked for hardware capability.
+ * Also if a party is removed, the conference is checked again.
+ *
+ * There are 3 different solutions: -1 = software, 0 = hardware-crossconnect
+ * 1-n = hardware-conference. The n will give the conference number.
+ *
+ * Depending on the change after removal or insertion of a party, hardware
+ * commands are given.
+ *
+ * The current solution is stored within the struct dsp_conf entry.
+ */
+
+/*
+ * HOW THE CMX WORKS:
+ *
+ * There are 3 types of interaction: One member is alone, in this case only
+ * data flow from upper to lower layer is done.
+ * Two members will also exchange their data so they are crossconnected.
+ * Three or more members will be added in a conference and will hear each
+ * other but will not receive their own speech (echo) if not enabled.
+ *
+ * Features of CMX are:
+ *  - Crossconnecting or even conference, if more than two members are together.
+ *  - Force mixing of transmit data with other crossconnect/conference members.
+ *  - Echo generation to benchmark the delay of audio processing.
+ *  - Use hardware to minimize cpu load, disable FIFO load and minimize delay.
+ *  - Dejittering and clock generation.
+ *
+ * There are 2 buffers:
+ *
+ *
+ * RX-Buffer
+ *                 R             W
+ *                 |             |
+ * ----------------+-------------+-------------------
+ *
+ * The rx-buffer is a ring buffer used to store the received data for each
+ * individual member. This is only the case if data needs to be dejittered
+ * or in case of a conference where different clocks require reclocking.
+ * The transmit-clock (R) will read the buffer.
+ * If the clock overruns the write-pointer, we will have a buffer underrun.
+ * If the write pointer always has a certain distance from the transmit-
+ * clock, we will have a delay. The delay will dynamically be increased and
+ * reduced.
+ *
+ *
+ * TX-Buffer
+ *                  R        W
+ *                  |        |
+ * -----------------+--------+-----------------------
+ *
+ * The tx-buffer is a ring buffer to queue the transmit data from user space
+ * until it will be mixed or sent. There are two pointers, R and W. If the write
+ * pointer W would reach or overrun R, the buffer would overrun. In this case
+ * (some) data is dropped so that it will not overrun.
+ * Additionally a dynamic dejittering can be enabled. this allows data from
+ * user space that have jitter and different clock source.
+ *
+ *
+ * Clock:
+ *
+ * A Clock is not required, if the data source has exactly one clock. In this
+ * case the data source is forwarded to the destination.
+ *
+ * A Clock is required, because the data source
+ *  - has multiple clocks.
+ *  - has no usable clock due to jitter or packet loss (VoIP).
+ * In this case the system's clock is used. The clock resolution depends on
+ * the jiffie resolution.
+ *
+ * If a member joins a conference:
+ *
+ * - If a member joins, its rx_buff is set to silence and change read pointer
+ *   to transmit clock.
+ *
+ * The procedure of received data from card is explained in cmx_receive.
+ * The procedure of received data from user space is explained in cmx_transmit.
+ * The procedure of transmit data to card is cmx_send.
+ *
+ *
+ * Interaction with other features:
+ *
+ * DTMF:
+ * DTMF decoding is done before the data is crossconnected.
+ *
+ * Volume change:
+ * Changing rx-volume is done before the data is crossconnected. The tx-volume
+ * must be changed whenever data is transmitted to the card by the cmx.
+ *
+ * Tones:
+ * If a tone is enabled, it will be processed whenever data is transmitted to
+ * the card. It will replace the tx-data from the user space.
+ * If tones are generated by hardware, this conference member is removed for
+ * this time.
+ *
+ * Disable rx-data:
+ * If cmx is realized in hardware, rx data will be disabled if requested by
+ * the upper layer. If dtmf decoding is done by software and enabled, rx data
+ * will not be disabled but blocked to the upper layer.
+ *
+ * HFC conference engine:
+ * If it is possible to realize all features using hardware, hardware will be
+ * used if not forbidden by control command. Disabling rx-data provides
+ * absolutely traffic free audio processing. (except for the quick 1-frame
+ * upload of a tone loop, only once for a new tone)
+ *
+ */
+
+/* delay.h is required for hw_lock.h */
+
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/mISDNif.h>
+#include <linux/mISDNdsp.h>
+#include "core.h"
+#include "dsp.h"
+/*
+ * debugging of multi party conference,
+ * by using conference even with two members
+ */
+
+/* #define CMX_CONF_DEBUG */
+
+/*#define CMX_DEBUG * massive read/write pointer output */
+/*#define CMX_DELAY_DEBUG * gives rx-buffer delay overview */
+/*#define CMX_TX_DEBUG * massive read/write on tx-buffer with content */
+
+/*
+ * debug cmx memory structure
+ */
+void
+dsp_cmx_debug(struct dsp *dsp)
+{
+	struct dsp_conf	*conf;
+	struct dsp_conf_member	*member;
+	struct dsp		*odsp;
+
+	printk(KERN_DEBUG "-----Current DSP\n");
+	list_for_each_entry(odsp, &dsp_ilist, list) {
+		printk(KERN_DEBUG "* %s hardecho=%d softecho=%d txmix=%d",
+		       odsp->name, odsp->echo.hardware, odsp->echo.software,
+		       odsp->tx_mix);
+		if (odsp->conf)
+			printk(" (Conf %d)", odsp->conf->id);
+		if (dsp == odsp)
+			printk(" *this*");
+		printk("\n");
+	}
+	printk(KERN_DEBUG "-----Current Conf:\n");
+	list_for_each_entry(conf, &conf_ilist, list) {
+		printk(KERN_DEBUG "* Conf %d (%p)\n", conf->id, conf);
+		list_for_each_entry(member, &conf->mlist, list) {
+			printk(KERN_DEBUG
+			       "  - member = %s (slot_tx %d, bank_tx %d, "
+			       "slot_rx %d, bank_rx %d hfc_conf %d "
+			       "tx_data %d rx_is_off %d)%s\n",
+			       member->dsp->name, member->dsp->pcm_slot_tx,
+			       member->dsp->pcm_bank_tx, member->dsp->pcm_slot_rx,
+			       member->dsp->pcm_bank_rx, member->dsp->hfc_conf,
+			       member->dsp->tx_data, member->dsp->rx_is_off,
+			       (member->dsp == dsp) ? " *this*" : "");
+		}
+	}
+	printk(KERN_DEBUG "-----end\n");
+}
+
+/*
+ * search conference
+ */
+static struct dsp_conf *
+dsp_cmx_search_conf(u32 id)
+{
+	struct dsp_conf *conf;
+
+	if (!id) {
+		printk(KERN_WARNING "%s: conference ID is 0.\n", __func__);
+		return NULL;
+	}
+
+	/* search conference */
+	list_for_each_entry(conf, &conf_ilist, list)
+		if (conf->id == id)
+			return conf;
+
+	return NULL;
+}
+
+
+/*
+ * add member to conference
+ */
+static int
+dsp_cmx_add_conf_member(struct dsp *dsp, struct dsp_conf *conf)
+{
+	struct dsp_conf_member *member;
+
+	if (!conf || !dsp) {
+		printk(KERN_WARNING "%s: conf or dsp is 0.\n", __func__);
+		return -EINVAL;
+	}
+	if (dsp->member) {
+		printk(KERN_WARNING "%s: dsp is already member in a conf.\n",
+		       __func__);
+		return -EINVAL;
+	}
+
+	if (dsp->conf) {
+		printk(KERN_WARNING "%s: dsp is already in a conf.\n",
+		       __func__);
+		return -EINVAL;
+	}
+
+	member = kzalloc(sizeof(struct dsp_conf_member), GFP_ATOMIC);
+	if (!member) {
+		printk(KERN_ERR "kzalloc struct dsp_conf_member failed\n");
+		return -ENOMEM;
+	}
+	member->dsp = dsp;
+	/* clear rx buffer */
+	memset(dsp->rx_buff, dsp_silence, sizeof(dsp->rx_buff));
+	dsp->rx_init = 1; /* rx_W and rx_R will be adjusted on first frame */
+	dsp->rx_W = 0;
+	dsp->rx_R = 0;
+
+	list_add_tail(&member->list, &conf->mlist);
+
+	dsp->conf = conf;
+	dsp->member = member;
+
+	return 0;
+}
+
+
+/*
+ * del member from conference
+ */
+int
+dsp_cmx_del_conf_member(struct dsp *dsp)
+{
+	struct dsp_conf_member *member;
+
+	if (!dsp) {
+		printk(KERN_WARNING "%s: dsp is 0.\n",
+		       __func__);
+		return -EINVAL;
+	}
+
+	if (!dsp->conf) {
+		printk(KERN_WARNING "%s: dsp is not in a conf.\n",
+		       __func__);
+		return -EINVAL;
+	}
+
+	if (list_empty(&dsp->conf->mlist)) {
+		printk(KERN_WARNING "%s: dsp has linked an empty conf.\n",
+		       __func__);
+		return -EINVAL;
+	}
+
+	/* find us in conf */
+	list_for_each_entry(member, &dsp->conf->mlist, list) {
+		if (member->dsp == dsp) {
+			list_del(&member->list);
+			dsp->conf = NULL;
+			dsp->member = NULL;
+			kfree(member);
+			return 0;
+		}
+	}
+	printk(KERN_WARNING
+	       "%s: dsp is not present in its own conf_member list.\n",
+	       __func__);
+
+	return -EINVAL;
+}
+
+
+/*
+ * new conference
+ */
+static struct dsp_conf
+*dsp_cmx_new_conf(u32 id)
+{
+	struct dsp_conf *conf;
+
+	if (!id) {
+		printk(KERN_WARNING "%s: id is 0.\n",
+		       __func__);
+		return NULL;
+	}
+
+	conf = kzalloc(sizeof(struct dsp_conf), GFP_ATOMIC);
+	if (!conf) {
+		printk(KERN_ERR "kzalloc struct dsp_conf failed\n");
+		return NULL;
+	}
+	INIT_LIST_HEAD(&conf->mlist);
+	conf->id = id;
+
+	list_add_tail(&conf->list, &conf_ilist);
+
+	return conf;
+}
+
+
+/*
+ * del conference
+ */
+int
+dsp_cmx_del_conf(struct dsp_conf *conf)
+{
+	if (!conf) {
+		printk(KERN_WARNING "%s: conf is null.\n",
+		       __func__);
+		return -EINVAL;
+	}
+
+	if (!list_empty(&conf->mlist)) {
+		printk(KERN_WARNING "%s: conf not empty.\n",
+		       __func__);
+		return -EINVAL;
+	}
+	list_del(&conf->list);
+	kfree(conf);
+
+	return 0;
+}
+
+
+/*
+ * send HW message to hfc card
+ */
+static void
+dsp_cmx_hw_message(struct dsp *dsp, u32 message, u32 param1, u32 param2,
+		   u32 param3, u32 param4)
+{
+	struct mISDN_ctrl_req cq;
+
+	memset(&cq, 0, sizeof(cq));
+	cq.op = message;
+	cq.p1 = param1 | (param2 << 8);
+	cq.p2 = param3 | (param4 << 8);
+	if (dsp->ch.peer)
+		dsp->ch.peer->ctrl(dsp->ch.peer, CONTROL_CHANNEL, &cq);
+}
+
+
+/*
+ * do hardware update and set the software/hardware flag
+ *
+ * either a conference or a dsp instance can be given
+ * if only dsp instance is given, the instance is not associated with a conf
+ * and therefore removed. if a conference is given, the dsp is expected to
+ * be member of that conference.
+ */
+void
+dsp_cmx_hardware(struct dsp_conf *conf, struct dsp *dsp)
+{
+	struct dsp_conf_member	*member, *nextm;
+	struct dsp		*finddsp;
+	int		memb = 0, i, ii, i1, i2;
+	int		freeunits[8];
+	u_char		freeslots[256];
+	int		same_hfc = -1, same_pcm = -1, current_conf = -1,
+		all_conf = 1, tx_data = 0;
+
+	/* dsp gets updated (no conf) */
+	if (!conf) {
+		if (!dsp)
+			return;
+		if (dsp_debug & DEBUG_DSP_CMX)
+			printk(KERN_DEBUG "%s checking dsp %s\n",
+			       __func__, dsp->name);
+	one_member:
+		/* remove HFC conference if enabled */
+		if (dsp->hfc_conf >= 0) {
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "%s removing %s from HFC conf %d "
+				       "because dsp is split\n", __func__,
+				       dsp->name, dsp->hfc_conf);
+			dsp_cmx_hw_message(dsp, MISDN_CTRL_HFC_CONF_SPLIT,
+					   0, 0, 0, 0);
+			dsp->hfc_conf = -1;
+		}
+		/* process hw echo */
+		if (dsp->features.pcm_banks < 1)
+			return;
+		if (!dsp->echo.software && !dsp->echo.hardware) {
+			/* NO ECHO: remove PCM slot if assigned */
+			if (dsp->pcm_slot_tx >= 0 || dsp->pcm_slot_rx >= 0) {
+				if (dsp_debug & DEBUG_DSP_CMX)
+					printk(KERN_DEBUG "%s removing %s from"
+					       " PCM slot %d (TX) %d (RX) because"
+					       " dsp is split (no echo)\n",
+					       __func__, dsp->name,
+					       dsp->pcm_slot_tx, dsp->pcm_slot_rx);
+				dsp_cmx_hw_message(dsp, MISDN_CTRL_HFC_PCM_DISC,
+						   0, 0, 0, 0);
+				dsp->pcm_slot_tx = -1;
+				dsp->pcm_bank_tx = -1;
+				dsp->pcm_slot_rx = -1;
+				dsp->pcm_bank_rx = -1;
+			}
+			return;
+		}
+		/* echo is enabled, find out if we use soft or hardware */
+		dsp->echo.software = dsp->tx_data;
+		dsp->echo.hardware = 0;
+		/* ECHO: already echo */
+		if (dsp->pcm_slot_tx >= 0 && dsp->pcm_slot_rx < 0 &&
+		    dsp->pcm_bank_tx == 2 && dsp->pcm_bank_rx == 2) {
+			dsp->echo.hardware = 1;
+			return;
+		}
+		/* ECHO: if slot already assigned */
+		if (dsp->pcm_slot_tx >= 0) {
+			dsp->pcm_slot_rx = dsp->pcm_slot_tx;
+			dsp->pcm_bank_tx = 2; /* 2 means loop */
+			dsp->pcm_bank_rx = 2;
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "%s refresh %s for echo using slot %d\n",
+				       __func__, dsp->name,
+				       dsp->pcm_slot_tx);
+			dsp_cmx_hw_message(dsp, MISDN_CTRL_HFC_PCM_CONN,
+					   dsp->pcm_slot_tx, 2, dsp->pcm_slot_rx, 2);
+			dsp->echo.hardware = 1;
+			return;
+		}
+		/* ECHO: find slot */
+		dsp->pcm_slot_tx = -1;
+		dsp->pcm_slot_rx = -1;
+		memset(freeslots, 1, sizeof(freeslots));
+		list_for_each_entry(finddsp, &dsp_ilist, list) {
+			if (finddsp->features.pcm_id == dsp->features.pcm_id) {
+				if (finddsp->pcm_slot_rx >= 0 &&
+				    finddsp->pcm_slot_rx < sizeof(freeslots))
+					freeslots[finddsp->pcm_slot_rx] = 0;
+				if (finddsp->pcm_slot_tx >= 0 &&
+				    finddsp->pcm_slot_tx < sizeof(freeslots))
+					freeslots[finddsp->pcm_slot_tx] = 0;
+			}
+		}
+		i = 0;
+		ii = dsp->features.pcm_slots;
+		while (i < ii) {
+			if (freeslots[i])
+				break;
+			i++;
+		}
+		if (i == ii) {
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "%s no slot available for echo\n",
+				       __func__);
+			/* no more slots available */
+			dsp->echo.software = 1;
+			return;
+		}
+		/* assign free slot */
+		dsp->pcm_slot_tx = i;
+		dsp->pcm_slot_rx = i;
+		dsp->pcm_bank_tx = 2; /* loop */
+		dsp->pcm_bank_rx = 2;
+		if (dsp_debug & DEBUG_DSP_CMX)
+			printk(KERN_DEBUG
+			       "%s assign echo for %s using slot %d\n",
+			       __func__, dsp->name, dsp->pcm_slot_tx);
+		dsp_cmx_hw_message(dsp, MISDN_CTRL_HFC_PCM_CONN,
+				   dsp->pcm_slot_tx, 2, dsp->pcm_slot_rx, 2);
+		dsp->echo.hardware = 1;
+		return;
+	}
+
+	/* conf gets updated (all members) */
+	if (dsp_debug & DEBUG_DSP_CMX)
+		printk(KERN_DEBUG "%s checking conference %d\n",
+		       __func__, conf->id);
+
+	if (list_empty(&conf->mlist)) {
+		printk(KERN_ERR "%s: conference without members\n",
+		       __func__);
+		return;
+	}
+	member = list_entry(conf->mlist.next, struct dsp_conf_member, list);
+	same_hfc = member->dsp->features.hfc_id;
+	same_pcm = member->dsp->features.pcm_id;
+	/* check all members in our conference */
+	list_for_each_entry(member, &conf->mlist, list) {
+		/* check if member uses mixing */
+		if (member->dsp->tx_mix) {
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "%s dsp %s cannot form a conf, because "
+				       "tx_mix is turned on\n", __func__,
+				       member->dsp->name);
+		conf_software:
+			list_for_each_entry(member, &conf->mlist, list) {
+				dsp = member->dsp;
+				/* remove HFC conference if enabled */
+				if (dsp->hfc_conf >= 0) {
+					if (dsp_debug & DEBUG_DSP_CMX)
+						printk(KERN_DEBUG
+						       "%s removing %s from HFC "
+						       "conf %d because not "
+						       "possible with hardware\n",
+						       __func__,
+						       dsp->name,
+						       dsp->hfc_conf);
+					dsp_cmx_hw_message(dsp,
+							   MISDN_CTRL_HFC_CONF_SPLIT,
+							   0, 0, 0, 0);
+					dsp->hfc_conf = -1;
+				}
+				/* remove PCM slot if assigned */
+				if (dsp->pcm_slot_tx >= 0 ||
+				    dsp->pcm_slot_rx >= 0) {
+					if (dsp_debug & DEBUG_DSP_CMX)
+						printk(KERN_DEBUG "%s removing "
+						       "%s from PCM slot %d (TX)"
+						       " slot %d (RX) because not"
+						       " possible with hardware\n",
+						       __func__,
+						       dsp->name,
+						       dsp->pcm_slot_tx,
+						       dsp->pcm_slot_rx);
+					dsp_cmx_hw_message(dsp,
+							   MISDN_CTRL_HFC_PCM_DISC,
+							   0, 0, 0, 0);
+					dsp->pcm_slot_tx = -1;
+					dsp->pcm_bank_tx = -1;
+					dsp->pcm_slot_rx = -1;
+					dsp->pcm_bank_rx = -1;
+				}
+			}
+			conf->hardware = 0;
+			conf->software = 1;
+			return;
+		}
+		/* check if member has echo turned on */
+		if (member->dsp->echo.hardware || member->dsp->echo.software) {
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "%s dsp %s cannot form a conf, because "
+				       "echo is turned on\n", __func__,
+				       member->dsp->name);
+			goto conf_software;
+		}
+		/* check if member has tx_mix turned on */
+		if (member->dsp->tx_mix) {
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "%s dsp %s cannot form a conf, because "
+				       "tx_mix is turned on\n",
+				       __func__, member->dsp->name);
+			goto conf_software;
+		}
+		/* check if member changes volume at an not suppoted level */
+		if (member->dsp->tx_volume) {
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "%s dsp %s cannot form a conf, because "
+				       "tx_volume is changed\n",
+				       __func__, member->dsp->name);
+			goto conf_software;
+		}
+		if (member->dsp->rx_volume) {
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "%s dsp %s cannot form a conf, because "
+				       "rx_volume is changed\n",
+				       __func__, member->dsp->name);
+			goto conf_software;
+		}
+		/* check if tx-data turned on */
+		if (member->dsp->tx_data) {
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "%s dsp %s tx_data is turned on\n",
+				       __func__, member->dsp->name);
+			tx_data = 1;
+		}
+		/* check if pipeline exists */
+		if (member->dsp->pipeline.inuse) {
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "%s dsp %s cannot form a conf, because "
+				       "pipeline exists\n", __func__,
+				       member->dsp->name);
+			goto conf_software;
+		}
+		/* check if encryption is enabled */
+		if (member->dsp->bf_enable) {
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG "%s dsp %s cannot form a "
+				       "conf, because encryption is enabled\n",
+				       __func__, member->dsp->name);
+			goto conf_software;
+		}
+		/* check if member is on a card with PCM support */
+		if (member->dsp->features.pcm_id < 0) {
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "%s dsp %s cannot form a conf, because "
+				       "dsp has no PCM bus\n",
+				       __func__, member->dsp->name);
+			goto conf_software;
+		}
+		/* check if relations are on the same PCM bus */
+		if (member->dsp->features.pcm_id != same_pcm) {
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "%s dsp %s cannot form a conf, because "
+				       "dsp is on a different PCM bus than the "
+				       "first dsp\n",
+				       __func__, member->dsp->name);
+			goto conf_software;
+		}
+		/* determine if members are on the same hfc chip */
+		if (same_hfc != member->dsp->features.hfc_id)
+			same_hfc = -1;
+		/* if there are members already in a conference */
+		if (current_conf < 0 && member->dsp->hfc_conf >= 0)
+			current_conf = member->dsp->hfc_conf;
+		/* if any member is not in a conference */
+		if (member->dsp->hfc_conf < 0)
+			all_conf = 0;
+
+		memb++;
+	}
+
+	/* if no member, this is an error */
+	if (memb < 1)
+		return;
+
+	/* one member */
+	if (memb == 1) {
+		if (dsp_debug & DEBUG_DSP_CMX)
+			printk(KERN_DEBUG
+			       "%s conf %d cannot form a HW conference, "
+			       "because dsp is alone\n", __func__, conf->id);
+		conf->hardware = 0;
+		conf->software = 0;
+		member = list_entry(conf->mlist.next, struct dsp_conf_member,
+				    list);
+		dsp = member->dsp;
+		goto one_member;
+	}
+
+	/*
+	 * ok, now we are sure that all members are on the same pcm.
+	 * now we will see if we have only two members, so we can do
+	 * crossconnections, which don't have any limitations.
+	 */
+
+	/* if we have only two members */
+	if (memb == 2) {
+		member = list_entry(conf->mlist.next, struct dsp_conf_member,
+				    list);
+		nextm = list_entry(member->list.next, struct dsp_conf_member,
+				   list);
+		/* remove HFC conference if enabled */
+		if (member->dsp->hfc_conf >= 0) {
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "%s removing %s from HFC conf %d because "
+				       "two parties require only a PCM slot\n",
+				       __func__, member->dsp->name,
+				       member->dsp->hfc_conf);
+			dsp_cmx_hw_message(member->dsp,
+					   MISDN_CTRL_HFC_CONF_SPLIT, 0, 0, 0, 0);
+			member->dsp->hfc_conf = -1;
+		}
+		if (nextm->dsp->hfc_conf >= 0) {
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "%s removing %s from HFC conf %d because "
+				       "two parties require only a PCM slot\n",
+				       __func__, nextm->dsp->name,
+				       nextm->dsp->hfc_conf);
+			dsp_cmx_hw_message(nextm->dsp,
+					   MISDN_CTRL_HFC_CONF_SPLIT, 0, 0, 0, 0);
+			nextm->dsp->hfc_conf = -1;
+		}
+		/* if members have two banks (and not on the same chip) */
+		if (member->dsp->features.pcm_banks > 1 &&
+		    nextm->dsp->features.pcm_banks > 1 &&
+		    member->dsp->features.hfc_id !=
+		    nextm->dsp->features.hfc_id) {
+			/* if both members have same slots with crossed banks */
+			if (member->dsp->pcm_slot_tx >= 0 &&
+			    member->dsp->pcm_slot_rx >= 0 &&
+			    nextm->dsp->pcm_slot_tx >= 0 &&
+			    nextm->dsp->pcm_slot_rx >= 0 &&
+			    nextm->dsp->pcm_slot_tx ==
+			    member->dsp->pcm_slot_rx &&
+			    nextm->dsp->pcm_slot_rx ==
+			    member->dsp->pcm_slot_tx &&
+			    nextm->dsp->pcm_slot_tx ==
+			    member->dsp->pcm_slot_tx &&
+			    member->dsp->pcm_bank_tx !=
+			    member->dsp->pcm_bank_rx &&
+			    nextm->dsp->pcm_bank_tx !=
+			    nextm->dsp->pcm_bank_rx) {
+				/* all members have same slot */
+				if (dsp_debug & DEBUG_DSP_CMX)
+					printk(KERN_DEBUG
+					       "%s dsp %s & %s stay joined on "
+					       "PCM slot %d bank %d (TX) bank %d "
+					       "(RX) (on different chips)\n",
+					       __func__,
+					       member->dsp->name,
+					       nextm->dsp->name,
+					       member->dsp->pcm_slot_tx,
+					       member->dsp->pcm_bank_tx,
+					       member->dsp->pcm_bank_rx);
+				conf->hardware = 1;
+				conf->software = tx_data;
+				return;
+			}
+			/* find a new slot */
+			memset(freeslots, 1, sizeof(freeslots));
+			list_for_each_entry(dsp, &dsp_ilist, list) {
+				if (dsp != member->dsp &&
+				    dsp != nextm->dsp &&
+				    member->dsp->features.pcm_id ==
+				    dsp->features.pcm_id) {
+					if (dsp->pcm_slot_rx >= 0 &&
+					    dsp->pcm_slot_rx <
+					    sizeof(freeslots))
+						freeslots[dsp->pcm_slot_rx] = 0;
+					if (dsp->pcm_slot_tx >= 0 &&
+					    dsp->pcm_slot_tx <
+					    sizeof(freeslots))
+						freeslots[dsp->pcm_slot_tx] = 0;
+				}
+			}
+			i = 0;
+			ii = member->dsp->features.pcm_slots;
+			while (i < ii) {
+				if (freeslots[i])
+					break;
+				i++;
+			}
+			if (i == ii) {
+				if (dsp_debug & DEBUG_DSP_CMX)
+					printk(KERN_DEBUG
+					       "%s no slot available for "
+					       "%s & %s\n", __func__,
+					       member->dsp->name,
+					       nextm->dsp->name);
+				/* no more slots available */
+				goto conf_software;
+			}
+			/* assign free slot */
+			member->dsp->pcm_slot_tx = i;
+			member->dsp->pcm_slot_rx = i;
+			nextm->dsp->pcm_slot_tx = i;
+			nextm->dsp->pcm_slot_rx = i;
+			member->dsp->pcm_bank_rx = 0;
+			member->dsp->pcm_bank_tx = 1;
+			nextm->dsp->pcm_bank_rx = 1;
+			nextm->dsp->pcm_bank_tx = 0;
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "%s adding %s & %s to new PCM slot %d "
+				       "(TX and RX on different chips) because "
+				       "both members have not same slots\n",
+				       __func__,
+				       member->dsp->name,
+				       nextm->dsp->name,
+				       member->dsp->pcm_slot_tx);
+			dsp_cmx_hw_message(member->dsp, MISDN_CTRL_HFC_PCM_CONN,
+					   member->dsp->pcm_slot_tx, member->dsp->pcm_bank_tx,
+					   member->dsp->pcm_slot_rx, member->dsp->pcm_bank_rx);
+			dsp_cmx_hw_message(nextm->dsp, MISDN_CTRL_HFC_PCM_CONN,
+					   nextm->dsp->pcm_slot_tx, nextm->dsp->pcm_bank_tx,
+					   nextm->dsp->pcm_slot_rx, nextm->dsp->pcm_bank_rx);
+			conf->hardware = 1;
+			conf->software = tx_data;
+			return;
+			/* if members have one bank (or on the same chip) */
+		} else {
+			/* if both members have different crossed slots */
+			if (member->dsp->pcm_slot_tx >= 0 &&
+			    member->dsp->pcm_slot_rx >= 0 &&
+			    nextm->dsp->pcm_slot_tx >= 0 &&
+			    nextm->dsp->pcm_slot_rx >= 0 &&
+			    nextm->dsp->pcm_slot_tx ==
+			    member->dsp->pcm_slot_rx &&
+			    nextm->dsp->pcm_slot_rx ==
+			    member->dsp->pcm_slot_tx &&
+			    member->dsp->pcm_slot_tx !=
+			    member->dsp->pcm_slot_rx &&
+			    member->dsp->pcm_bank_tx == 0 &&
+			    member->dsp->pcm_bank_rx == 0 &&
+			    nextm->dsp->pcm_bank_tx == 0 &&
+			    nextm->dsp->pcm_bank_rx == 0) {
+				/* all members have same slot */
+				if (dsp_debug & DEBUG_DSP_CMX)
+					printk(KERN_DEBUG
+					       "%s dsp %s & %s stay joined on PCM "
+					       "slot %d (TX) %d (RX) on same chip "
+					       "or one bank PCM)\n", __func__,
+					       member->dsp->name,
+					       nextm->dsp->name,
+					       member->dsp->pcm_slot_tx,
+					       member->dsp->pcm_slot_rx);
+				conf->hardware = 1;
+				conf->software = tx_data;
+				return;
+			}
+			/* find two new slot */
+			memset(freeslots, 1, sizeof(freeslots));
+			list_for_each_entry(dsp, &dsp_ilist, list) {
+				if (dsp != member->dsp &&
+				    dsp != nextm->dsp &&
+				    member->dsp->features.pcm_id ==
+				    dsp->features.pcm_id) {
+					if (dsp->pcm_slot_rx >= 0 &&
+					    dsp->pcm_slot_rx <
+					    sizeof(freeslots))
+						freeslots[dsp->pcm_slot_rx] = 0;
+					if (dsp->pcm_slot_tx >= 0 &&
+					    dsp->pcm_slot_tx <
+					    sizeof(freeslots))
+						freeslots[dsp->pcm_slot_tx] = 0;
+				}
+			}
+			i1 = 0;
+			ii = member->dsp->features.pcm_slots;
+			while (i1 < ii) {
+				if (freeslots[i1])
+					break;
+				i1++;
+			}
+			if (i1 == ii) {
+				if (dsp_debug & DEBUG_DSP_CMX)
+					printk(KERN_DEBUG
+					       "%s no slot available "
+					       "for %s & %s\n", __func__,
+					       member->dsp->name,
+					       nextm->dsp->name);
+				/* no more slots available */
+				goto conf_software;
+			}
+			i2 = i1 + 1;
+			while (i2 < ii) {
+				if (freeslots[i2])
+					break;
+				i2++;
+			}
+			if (i2 == ii) {
+				if (dsp_debug & DEBUG_DSP_CMX)
+					printk(KERN_DEBUG
+					       "%s no slot available "
+					       "for %s & %s\n",
+					       __func__,
+					       member->dsp->name,
+					       nextm->dsp->name);
+				/* no more slots available */
+				goto conf_software;
+			}
+			/* assign free slots */
+			member->dsp->pcm_slot_tx = i1;
+			member->dsp->pcm_slot_rx = i2;
+			nextm->dsp->pcm_slot_tx = i2;
+			nextm->dsp->pcm_slot_rx = i1;
+			member->dsp->pcm_bank_rx = 0;
+			member->dsp->pcm_bank_tx = 0;
+			nextm->dsp->pcm_bank_rx = 0;
+			nextm->dsp->pcm_bank_tx = 0;
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "%s adding %s & %s to new PCM slot %d "
+				       "(TX) %d (RX) on same chip or one bank "
+				       "PCM, because both members have not "
+				       "crossed slots\n", __func__,
+				       member->dsp->name,
+				       nextm->dsp->name,
+				       member->dsp->pcm_slot_tx,
+				       member->dsp->pcm_slot_rx);
+			dsp_cmx_hw_message(member->dsp, MISDN_CTRL_HFC_PCM_CONN,
+					   member->dsp->pcm_slot_tx, member->dsp->pcm_bank_tx,
+					   member->dsp->pcm_slot_rx, member->dsp->pcm_bank_rx);
+			dsp_cmx_hw_message(nextm->dsp, MISDN_CTRL_HFC_PCM_CONN,
+					   nextm->dsp->pcm_slot_tx, nextm->dsp->pcm_bank_tx,
+					   nextm->dsp->pcm_slot_rx, nextm->dsp->pcm_bank_rx);
+			conf->hardware = 1;
+			conf->software = tx_data;
+			return;
+		}
+	}
+
+	/*
+	 * if we have more than two, we may check if we have a conference
+	 * unit available on the chip. also all members must be on the same
+	 */
+
+	/* if not the same HFC chip */
+	if (same_hfc < 0) {
+		if (dsp_debug & DEBUG_DSP_CMX)
+			printk(KERN_DEBUG
+			       "%s conference %d cannot be formed, because "
+			       "members are on different chips or not "
+			       "on HFC chip\n",
+			       __func__, conf->id);
+		goto conf_software;
+	}
+
+	/* for more than two members.. */
+
+	/* if all members already have the same conference */
+	if (all_conf) {
+		conf->hardware = 1;
+		conf->software = tx_data;
+		return;
+	}
+
+	/*
+	 * if there is an existing conference, but not all members have joined
+	 */
+	if (current_conf >= 0) {
+	join_members:
+		list_for_each_entry(member, &conf->mlist, list) {
+			/* if no conference engine on our chip, change to
+			 * software */
+			if (!member->dsp->features.hfc_conf)
+				goto conf_software;
+			/* in case of hdlc, change to software */
+			if (member->dsp->hdlc)
+				goto conf_software;
+			/* join to current conference */
+			if (member->dsp->hfc_conf == current_conf)
+				continue;
+			/* get a free timeslot first */
+			memset(freeslots, 1, sizeof(freeslots));
+			list_for_each_entry(dsp, &dsp_ilist, list) {
+				/*
+				 * not checking current member, because
+				 * slot will be overwritten.
+				 */
+				if (
+					dsp != member->dsp &&
+					/* dsp must be on the same PCM */
+					member->dsp->features.pcm_id ==
+					dsp->features.pcm_id) {
+					/* dsp must be on a slot */
+					if (dsp->pcm_slot_tx >= 0 &&
+					    dsp->pcm_slot_tx <
+					    sizeof(freeslots))
+						freeslots[dsp->pcm_slot_tx] = 0;
+					if (dsp->pcm_slot_rx >= 0 &&
+					    dsp->pcm_slot_rx <
+					    sizeof(freeslots))
+						freeslots[dsp->pcm_slot_rx] = 0;
+				}
+			}
+			i = 0;
+			ii = member->dsp->features.pcm_slots;
+			while (i < ii) {
+				if (freeslots[i])
+					break;
+				i++;
+			}
+			if (i == ii) {
+				/* no more slots available */
+				if (dsp_debug & DEBUG_DSP_CMX)
+					printk(KERN_DEBUG
+					       "%s conference %d cannot be formed,"
+					       " because no slot free\n",
+					       __func__, conf->id);
+				goto conf_software;
+			}
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "%s changing dsp %s to HW conference "
+				       "%d slot %d\n", __func__,
+				       member->dsp->name, current_conf, i);
+			/* assign free slot & set PCM & join conf */
+			member->dsp->pcm_slot_tx = i;
+			member->dsp->pcm_slot_rx = i;
+			member->dsp->pcm_bank_tx = 2; /* loop */
+			member->dsp->pcm_bank_rx = 2;
+			member->dsp->hfc_conf = current_conf;
+			dsp_cmx_hw_message(member->dsp, MISDN_CTRL_HFC_PCM_CONN,
+					   i, 2, i, 2);
+			dsp_cmx_hw_message(member->dsp,
+					   MISDN_CTRL_HFC_CONF_JOIN, current_conf, 0, 0, 0);
+		}
+		conf->hardware = 1;
+		conf->software = tx_data;
+		return;
+	}
+
+	/*
+	 * no member is in a conference yet, so we find a free one
+	 */
+	memset(freeunits, 1, sizeof(freeunits));
+	list_for_each_entry(dsp, &dsp_ilist, list) {
+		/* dsp must be on the same chip */
+		if (dsp->features.hfc_id == same_hfc &&
+		    /* dsp must have joined a HW conference */
+		    dsp->hfc_conf >= 0 &&
+		    /* slot must be within range */
+		    dsp->hfc_conf < 8)
+			freeunits[dsp->hfc_conf] = 0;
+	}
+	i = 0;
+	ii = 8;
+	while (i < ii) {
+		if (freeunits[i])
+			break;
+		i++;
+	}
+	if (i == ii) {
+		/* no more conferences available */
+		if (dsp_debug & DEBUG_DSP_CMX)
+			printk(KERN_DEBUG
+			       "%s conference %d cannot be formed, because "
+			       "no conference number free\n",
+			       __func__, conf->id);
+		goto conf_software;
+	}
+	/* join all members */
+	current_conf = i;
+	goto join_members;
+}
+
+
+/*
+ * conf_id != 0: join or change conference
+ * conf_id == 0: split from conference if not already
+ */
+int
+dsp_cmx_conf(struct dsp *dsp, u32 conf_id)
+{
+	int err;
+	struct dsp_conf *conf;
+	struct dsp_conf_member	*member;
+
+	/* if conference doesn't change */
+	if (dsp->conf_id == conf_id)
+		return 0;
+
+	/* first remove us from current conf */
+	if (dsp->conf_id) {
+		if (dsp_debug & DEBUG_DSP_CMX)
+			printk(KERN_DEBUG "removing us from conference %d\n",
+			       dsp->conf->id);
+		/* remove us from conf */
+		conf = dsp->conf;
+		err = dsp_cmx_del_conf_member(dsp);
+		if (err)
+			return err;
+		dsp->conf_id = 0;
+
+		/* update hardware */
+		dsp_cmx_hardware(NULL, dsp);
+
+		/* conf now empty? */
+		if (list_empty(&conf->mlist)) {
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "conference is empty, so we remove it.\n");
+			err = dsp_cmx_del_conf(conf);
+			if (err)
+				return err;
+		} else {
+			/* update members left on conf */
+			dsp_cmx_hardware(conf, NULL);
+		}
+	}
+
+	/* if split */
+	if (!conf_id)
+		return 0;
+
+	/* now add us to conf */
+	if (dsp_debug & DEBUG_DSP_CMX)
+		printk(KERN_DEBUG "searching conference %d\n",
+		       conf_id);
+	conf = dsp_cmx_search_conf(conf_id);
+	if (!conf) {
+		if (dsp_debug & DEBUG_DSP_CMX)
+			printk(KERN_DEBUG
+			       "conference doesn't exist yet, creating.\n");
+		/* the conference doesn't exist, so we create */
+		conf = dsp_cmx_new_conf(conf_id);
+		if (!conf)
+			return -EINVAL;
+	} else if (!list_empty(&conf->mlist)) {
+		member = list_entry(conf->mlist.next, struct dsp_conf_member,
+				    list);
+		if (dsp->hdlc && !member->dsp->hdlc) {
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "cannot join transparent conference.\n");
+			return -EINVAL;
+		}
+		if (!dsp->hdlc && member->dsp->hdlc) {
+			if (dsp_debug & DEBUG_DSP_CMX)
+				printk(KERN_DEBUG
+				       "cannot join hdlc conference.\n");
+			return -EINVAL;
+		}
+	}
+	/* add conference member */
+	err = dsp_cmx_add_conf_member(dsp, conf);
+	if (err)
+		return err;
+	dsp->conf_id = conf_id;
+
+	/* if we are alone, we do nothing! */
+	if (list_empty(&conf->mlist)) {
+		if (dsp_debug & DEBUG_DSP_CMX)
+			printk(KERN_DEBUG
+			       "we are alone in this conference, so exit.\n");
+		/* update hardware */
+		dsp_cmx_hardware(NULL, dsp);
+		return 0;
+	}
+
+	/* update members on conf */
+	dsp_cmx_hardware(conf, NULL);
+
+	return 0;
+}
+
+#ifdef CMX_DELAY_DEBUG
+int delaycount;
+static void
+showdelay(struct dsp *dsp, int samples, int delay)
+{
+	char bar[] = "--------------------------------------------------|";
+	int sdelay;
+
+	delaycount += samples;
+	if (delaycount < 8000)
+		return;
+	delaycount = 0;
+
+	sdelay = delay * 50 / (dsp_poll << 2);
+
+	printk(KERN_DEBUG "DELAY (%s) %3d >%s\n", dsp->name, delay,
+	       sdelay > 50 ? "..." : bar + 50 - sdelay);
+}
+#endif
+
+/*
+ * audio data is received from card
+ */
+void
+dsp_cmx_receive(struct dsp *dsp, struct sk_buff *skb)
+{
+	u8 *d, *p;
+	int len = skb->len;
+	struct mISDNhead *hh = mISDN_HEAD_P(skb);
+	int w, i, ii;
+
+	/* check if we have sompen */
+	if (len < 1)
+		return;
+
+	/* half of the buffer should be larger than maximum packet size */
+	if (len >= CMX_BUFF_HALF) {
+		printk(KERN_ERR
+		       "%s line %d: packet from card is too large (%d bytes). "
+		       "please make card send smaller packets OR increase "
+		       "CMX_BUFF_SIZE\n", __FILE__, __LINE__, len);
+		return;
+	}
+
+	/*
+	 * initialize pointers if not already -
+	 * also add delay if requested by PH_SIGNAL
+	 */
+	if (dsp->rx_init) {
+		dsp->rx_init = 0;
+		if (dsp->features.unordered) {
+			dsp->rx_R = (hh->id & CMX_BUFF_MASK);
+			if (dsp->cmx_delay)
+				dsp->rx_W = (dsp->rx_R + dsp->cmx_delay)
+					& CMX_BUFF_MASK;
+			else
+				dsp->rx_W = (dsp->rx_R + (dsp_poll >> 1))
+					& CMX_BUFF_MASK;
+		} else {
+			dsp->rx_R = 0;
+			if (dsp->cmx_delay)
+				dsp->rx_W = dsp->cmx_delay;
+			else
+				dsp->rx_W = dsp_poll >> 1;
+		}
+	}
+	/* if frame contains time code, write directly */
+	if (dsp->features.unordered) {
+		dsp->rx_W = (hh->id & CMX_BUFF_MASK);
+		/* printk(KERN_DEBUG "%s %08x\n", dsp->name, hh->id); */
+	}
+	/*
+	 * if we underrun (or maybe overrun),
+	 * we set our new read pointer, and write silence to buffer
+	 */
+	if (((dsp->rx_W-dsp->rx_R) & CMX_BUFF_MASK) >= CMX_BUFF_HALF) {
+		if (dsp_debug & DEBUG_DSP_CLOCK)
+			printk(KERN_DEBUG
+			       "cmx_receive(dsp=%lx): UNDERRUN (or overrun the "
+			       "maximum delay), adjusting read pointer! "
+			       "(inst %s)\n", (u_long)dsp, dsp->name);
+		/* flush rx buffer and set delay to dsp_poll / 2 */
+		if (dsp->features.unordered) {
+			dsp->rx_R = (hh->id & CMX_BUFF_MASK);
+			if (dsp->cmx_delay)
+				dsp->rx_W = (dsp->rx_R + dsp->cmx_delay)
+					& CMX_BUFF_MASK;
+			else
+				dsp->rx_W = (dsp->rx_R + (dsp_poll >> 1))
+					& CMX_BUFF_MASK;
+		} else {
+			dsp->rx_R = 0;
+			if (dsp->cmx_delay)
+				dsp->rx_W = dsp->cmx_delay;
+			else
+				dsp->rx_W = dsp_poll >> 1;
+		}
+		memset(dsp->rx_buff, dsp_silence, sizeof(dsp->rx_buff));
+	}
+	/* if we have reached double delay, jump back to middle */
+	if (dsp->cmx_delay)
+		if (((dsp->rx_W - dsp->rx_R) & CMX_BUFF_MASK) >=
+		    (dsp->cmx_delay << 1)) {
+			if (dsp_debug & DEBUG_DSP_CLOCK)
+				printk(KERN_DEBUG
+				       "cmx_receive(dsp=%lx): OVERRUN (because "
+				       "twice the delay is reached), adjusting "
+				       "read pointer! (inst %s)\n",
+				       (u_long)dsp, dsp->name);
+			/* flush buffer */
+			if (dsp->features.unordered) {
+				dsp->rx_R = (hh->id & CMX_BUFF_MASK);
+				dsp->rx_W = (dsp->rx_R + dsp->cmx_delay)
+					& CMX_BUFF_MASK;
+			} else {
+				dsp->rx_R = 0;
+				dsp->rx_W = dsp->cmx_delay;
+			}
+			memset(dsp->rx_buff, dsp_silence, sizeof(dsp->rx_buff));
+		}
+
+	/* show where to write */
+#ifdef CMX_DEBUG
+	printk(KERN_DEBUG
+	       "cmx_receive(dsp=%lx): rx_R(dsp)=%05x rx_W(dsp)=%05x len=%d %s\n",
+	       (u_long)dsp, dsp->rx_R, dsp->rx_W, len, dsp->name);
+#endif
+
+	/* write data into rx_buffer */
+	p = skb->data;
+	d = dsp->rx_buff;
+	w = dsp->rx_W;
+	i = 0;
+	ii = len;
+	while (i < ii) {
+		d[w++ & CMX_BUFF_MASK] = *p++;
+		i++;
+	}
+
+	/* increase write-pointer */
+	dsp->rx_W = ((dsp->rx_W + len) & CMX_BUFF_MASK);
+#ifdef CMX_DELAY_DEBUG
+	showdelay(dsp, len, (dsp->rx_W-dsp->rx_R) & CMX_BUFF_MASK);
+#endif
+}
+
+
+/*
+ * send (mixed) audio data to card and control jitter
+ */
+static void
+dsp_cmx_send_member(struct dsp *dsp, int len, s32 *c, int members)
+{
+	struct dsp_conf *conf = dsp->conf;
+	struct dsp *member, *other;
+	register s32 sample;
+	u8 *d, *p, *q, *o_q;
+	struct sk_buff *nskb, *txskb;
+	int r, rr, t, tt, o_r, o_rr;
+	int preload = 0;
+	struct mISDNhead *hh, *thh;
+	int tx_data_only = 0;
+
+	/* don't process if: */
+	if (!dsp->b_active) { /* if not active */
+		dsp->last_tx = 0;
+		return;
+	}
+	if (((dsp->conf && dsp->conf->hardware) || /* hardware conf */
+	     dsp->echo.hardware) && /* OR hardware echo */
+	    dsp->tx_R == dsp->tx_W && /* AND no tx-data */
+	    !(dsp->tone.tone && dsp->tone.software)) { /* AND not soft tones */
+		if (!dsp->tx_data) { /* no tx_data for user space required */
+			dsp->last_tx = 0;
+			return;
+		}
+		if (dsp->conf && dsp->conf->software && dsp->conf->hardware)
+			tx_data_only = 1;
+		if (dsp->echo.software && dsp->echo.hardware)
+			tx_data_only = 1;
+	}
+
+#ifdef CMX_DEBUG
+	printk(KERN_DEBUG
+	       "SEND members=%d dsp=%s, conf=%p, rx_R=%05x rx_W=%05x\n",
+	       members, dsp->name, conf, dsp->rx_R, dsp->rx_W);
+#endif
+
+	/* preload if we have delay set */
+	if (dsp->cmx_delay && !dsp->last_tx) {
+		preload = len;
+		if (preload < 128)
+			preload = 128;
+	}
+
+	/* PREPARE RESULT */
+	nskb = mI_alloc_skb(len + preload, GFP_ATOMIC);
+	if (!nskb) {
+		printk(KERN_ERR
+		       "FATAL ERROR in mISDN_dsp.o: cannot alloc %d bytes\n",
+		       len + preload);
+		return;
+	}
+	hh = mISDN_HEAD_P(nskb);
+	hh->prim = PH_DATA_REQ;
+	hh->id = 0;
+	dsp->last_tx = 1;
+
+	/* set pointers, indexes and stuff */
+	member = dsp;
+	p = dsp->tx_buff; /* transmit data */
+	q = dsp->rx_buff; /* received data */
+	d = skb_put(nskb, preload + len); /* result */
+	t = dsp->tx_R; /* tx-pointers */
+	tt = dsp->tx_W;
+	r = dsp->rx_R; /* rx-pointers */
+	rr = (r + len) & CMX_BUFF_MASK;
+
+	/* preload with silence, if required */
+	if (preload) {
+		memset(d, dsp_silence, preload);
+		d += preload;
+	}
+
+	/* PROCESS TONES/TX-DATA ONLY */
+	if (dsp->tone.tone && dsp->tone.software) {
+		/* -> copy tone */
+		dsp_tone_copy(dsp, d, len);
+		dsp->tx_R = 0; /* clear tx buffer */
+		dsp->tx_W = 0;
+		goto send_packet;
+	}
+	/* if we have tx-data but do not use mixing */
+	if (!dsp->tx_mix && t != tt) {
+		/* -> send tx-data and continue when not enough */
+#ifdef CMX_TX_DEBUG
+		sprintf(debugbuf, "TX sending (%04x-%04x)%p: ", t, tt, p);
+#endif
+		while (r != rr && t != tt) {
+#ifdef CMX_TX_DEBUG
+			if (strlen(debugbuf) < 48)
+				sprintf(debugbuf + strlen(debugbuf), " %02x",
+					p[t]);
+#endif
+			*d++ = p[t]; /* write tx_buff */
+			t = (t + 1) & CMX_BUFF_MASK;
+			r = (r + 1) & CMX_BUFF_MASK;
+		}
+		if (r == rr) {
+			dsp->tx_R = t;
+#ifdef CMX_TX_DEBUG
+			printk(KERN_DEBUG "%s\n", debugbuf);
+#endif
+			goto send_packet;
+		}
+	}
+#ifdef CMX_TX_DEBUG
+	printk(KERN_DEBUG "%s\n", debugbuf);
+#endif
+
+	/* PROCESS DATA (one member / no conf) */
+	if (!conf || members <= 1) {
+		/* -> if echo is NOT enabled */
+		if (!dsp->echo.software) {
+			/* -> send tx-data if available or use 0-volume */
+			while (r != rr && t != tt) {
+				*d++ = p[t]; /* write tx_buff */
+				t = (t + 1) & CMX_BUFF_MASK;
+				r = (r + 1) & CMX_BUFF_MASK;
+			}
+			if (r != rr) {
+				if (dsp_debug & DEBUG_DSP_CLOCK)
+					printk(KERN_DEBUG "%s: RX empty\n",
+					       __func__);
+				memset(d, dsp_silence, (rr - r) & CMX_BUFF_MASK);
+			}
+			/* -> if echo is enabled */
+		} else {
+			/*
+			 * -> mix tx-data with echo if available,
+			 * or use echo only
+			 */
+			while (r != rr && t != tt) {
+				*d++ = dsp_audio_mix_law[(p[t] << 8) | q[r]];
+				t = (t + 1) & CMX_BUFF_MASK;
+				r = (r + 1) & CMX_BUFF_MASK;
+			}
+			while (r != rr) {
+				*d++ = q[r]; /* echo */
+				r = (r + 1) & CMX_BUFF_MASK;
+			}
+		}
+		dsp->tx_R = t;
+		goto send_packet;
+	}
+	/* PROCESS DATA (two members) */
+#ifdef CMX_CONF_DEBUG
+	if (0) {
+#else
+	if (members == 2) {
+#endif
+		/* "other" becomes other party */
+		other = (list_entry(conf->mlist.next,
+				    struct dsp_conf_member, list))->dsp;
+		if (other == member)
+			other = (list_entry(conf->mlist.prev,
+				    struct dsp_conf_member, list))->dsp;
+		o_q = other->rx_buff; /* received data */
+		o_rr = (other->rx_R + len) & CMX_BUFF_MASK;
+		/* end of rx-pointer */
+		o_r = (o_rr - rr + r) & CMX_BUFF_MASK;
+		/* start rx-pointer at current read position*/
+		/* -> if echo is NOT enabled */
+		if (!dsp->echo.software) {
+			/*
+			 * -> copy other member's rx-data,
+			 * if tx-data is available, mix
+			 */
+			while (o_r != o_rr && t != tt) {
+				*d++ = dsp_audio_mix_law[(p[t] << 8) | o_q[o_r]];
+				t = (t + 1) & CMX_BUFF_MASK;
+				o_r = (o_r + 1) & CMX_BUFF_MASK;
+			}
+			while (o_r != o_rr) {
+				*d++ = o_q[o_r];
+				o_r = (o_r + 1) & CMX_BUFF_MASK;
+			}
+			/* -> if echo is enabled */
+		} else {
+			/*
+			 * -> mix other member's rx-data with echo,
+			 * if tx-data is available, mix
+			 */
+			while (r != rr && t != tt) {
+				sample = dsp_audio_law_to_s32[p[t]] +
+					dsp_audio_law_to_s32[q[r]] +
+					dsp_audio_law_to_s32[o_q[o_r]];
+				if (sample < -32768)
+					sample = -32768;
+				else if (sample > 32767)
+					sample = 32767;
+				*d++ = dsp_audio_s16_to_law[sample & 0xffff];
+				/* tx-data + rx_data + echo */
+				t = (t + 1) & CMX_BUFF_MASK;
+				r = (r + 1) & CMX_BUFF_MASK;
+				o_r = (o_r + 1) & CMX_BUFF_MASK;
+			}
+			while (r != rr) {
+				*d++ = dsp_audio_mix_law[(q[r] << 8) | o_q[o_r]];
+				r = (r + 1) & CMX_BUFF_MASK;
+				o_r = (o_r + 1) & CMX_BUFF_MASK;
+			}
+		}
+		dsp->tx_R = t;
+		goto send_packet;
+	}
+	/* PROCESS DATA (three or more members) */
+	/* -> if echo is NOT enabled */
+	if (!dsp->echo.software) {
+		/*
+		 * -> subtract rx-data from conf-data,
+		 * if tx-data is available, mix
+		 */
+		while (r != rr && t != tt) {
+			sample = dsp_audio_law_to_s32[p[t]] + *c++ -
+				dsp_audio_law_to_s32[q[r]];
+			if (sample < -32768)
+				sample = -32768;
+			else if (sample > 32767)
+				sample = 32767;
+			*d++ = dsp_audio_s16_to_law[sample & 0xffff];
+			/* conf-rx+tx */
+			r = (r + 1) & CMX_BUFF_MASK;
+			t = (t + 1) & CMX_BUFF_MASK;
+		}
+		while (r != rr) {
+			sample = *c++ - dsp_audio_law_to_s32[q[r]];
+			if (sample < -32768)
+				sample = -32768;
+			else if (sample > 32767)
+				sample = 32767;
+			*d++ = dsp_audio_s16_to_law[sample & 0xffff];
+			/* conf-rx */
+			r = (r + 1) & CMX_BUFF_MASK;
+		}
+		/* -> if echo is enabled */
+	} else {
+		/*
+		 * -> encode conf-data, if tx-data
+		 * is available, mix
+		 */
+		while (r != rr && t != tt) {
+			sample = dsp_audio_law_to_s32[p[t]] + *c++;
+			if (sample < -32768)
+				sample = -32768;
+			else if (sample > 32767)
+				sample = 32767;
+			*d++ = dsp_audio_s16_to_law[sample & 0xffff];
+			/* conf(echo)+tx */
+			t = (t + 1) & CMX_BUFF_MASK;
+			r = (r + 1) & CMX_BUFF_MASK;
+		}
+		while (r != rr) {
+			sample = *c++;
+			if (sample < -32768)
+				sample = -32768;
+			else if (sample > 32767)
+				sample = 32767;
+			*d++ = dsp_audio_s16_to_law[sample & 0xffff];
+			/* conf(echo) */
+			r = (r + 1) & CMX_BUFF_MASK;
+		}
+	}
+	dsp->tx_R = t;
+	goto send_packet;
+
+send_packet:
+	/*
+	 * send tx-data if enabled - don't filter,
+	 * because we want what we send, not what we filtered
+	 */
+	if (dsp->tx_data) {
+		if (tx_data_only) {
+			hh->prim = DL_DATA_REQ;
+			hh->id = 0;
+			/* queue and trigger */
+			skb_queue_tail(&dsp->sendq, nskb);
+			schedule_work(&dsp->workq);
+			/* exit because only tx_data is used */
+			return;
+		} else {
+			txskb = mI_alloc_skb(len, GFP_ATOMIC);
+			if (!txskb) {
+				printk(KERN_ERR
+				       "FATAL ERROR in mISDN_dsp.o: "
+				       "cannot alloc %d bytes\n", len);
+			} else {
+				thh = mISDN_HEAD_P(txskb);
+				thh->prim = DL_DATA_REQ;
+				thh->id = 0;
+				skb_put_data(txskb, nskb->data + preload, len);
+				/* queue (trigger later) */
+				skb_queue_tail(&dsp->sendq, txskb);
+			}
+		}
+	}
+
+	/* send data only to card, if we don't just calculated tx_data */
+	/* adjust volume */
+	if (dsp->tx_volume)
+		dsp_change_volume(nskb, dsp->tx_volume);
+	/* pipeline */
+	if (dsp->pipeline.inuse)
+		dsp_pipeline_process_tx(&dsp->pipeline, nskb->data,
+					nskb->len);
+	/* crypt */
+	if (dsp->bf_enable)
+		dsp_bf_encrypt(dsp, nskb->data, nskb->len);
+	/* queue and trigger */
+	skb_queue_tail(&dsp->sendq, nskb);
+	schedule_work(&dsp->workq);
+}
+
+static u32	jittercount; /* counter for jitter check */
+struct timer_list dsp_spl_tl;
+unsigned long	dsp_spl_jiffies; /* calculate the next time to fire */
+static u16	dsp_count; /* last sample count */
+static int	dsp_count_valid; /* if we have last sample count */
+
+void
+dsp_cmx_send(struct timer_list *arg)
+{
+	struct dsp_conf *conf;
+	struct dsp_conf_member *member;
+	struct dsp *dsp;
+	int mustmix, members;
+	static s32 mixbuffer[MAX_POLL + 100];
+	s32 *c;
+	u8 *p, *q;
+	int r, rr;
+	int jittercheck = 0, delay, i;
+	u_long flags;
+	u16 length, count;
+
+	/* lock */
+	spin_lock_irqsave(&dsp_lock, flags);
+
+	if (!dsp_count_valid) {
+		dsp_count = mISDN_clock_get();
+		length = dsp_poll;
+		dsp_count_valid = 1;
+	} else {
+		count = mISDN_clock_get();
+		length = count - dsp_count;
+		dsp_count = count;
+	}
+	if (length > MAX_POLL + 100)
+		length = MAX_POLL + 100;
+	/* printk(KERN_DEBUG "len=%d dsp_count=0x%x\n", length, dsp_count); */
+
+	/*
+	 * check if jitter needs to be checked (this is every second)
+	 */
+	jittercount += length;
+	if (jittercount >= 8000) {
+		jittercount -= 8000;
+		jittercheck = 1;
+	}
+
+	/* loop all members that do not require conference mixing */
+	list_for_each_entry(dsp, &dsp_ilist, list) {
+		if (dsp->hdlc)
+			continue;
+		conf = dsp->conf;
+		mustmix = 0;
+		members = 0;
+		if (conf) {
+			members = list_count_nodes(&conf->mlist);
+#ifdef CMX_CONF_DEBUG
+			if (conf->software && members > 1)
+#else
+			if (conf->software && members > 2)
+#endif
+				mustmix = 1;
+		}
+
+		/* transmission required */
+		if (!mustmix) {
+			dsp_cmx_send_member(dsp, length, mixbuffer, members);
+
+			/*
+			 * unused mixbuffer is given to prevent a
+			 * potential null-pointer-bug
+			 */
+		}
+	}
+
+	/* loop all members that require conference mixing */
+	list_for_each_entry(conf, &conf_ilist, list) {
+		/* count members and check hardware */
+		members = list_count_nodes(&conf->mlist);
+#ifdef CMX_CONF_DEBUG
+		if (conf->software && members > 1) {
+#else
+		if (conf->software && members > 2) {
+#endif
+			/* check for hdlc conf */
+			member = list_entry(conf->mlist.next,
+					    struct dsp_conf_member, list);
+			if (member->dsp->hdlc)
+				continue;
+			/* mix all data */
+			memset(mixbuffer, 0, length * sizeof(s32));
+			list_for_each_entry(member, &conf->mlist, list) {
+				dsp = member->dsp;
+				/* get range of data to mix */
+				c = mixbuffer;
+				q = dsp->rx_buff;
+				r = dsp->rx_R;
+				rr = (r + length) & CMX_BUFF_MASK;
+				/* add member's data */
+				while (r != rr) {
+					*c++ += dsp_audio_law_to_s32[q[r]];
+					r = (r + 1) & CMX_BUFF_MASK;
+				}
+			}
+
+			/* process each member */
+			list_for_each_entry(member, &conf->mlist, list) {
+				/* transmission */
+				dsp_cmx_send_member(member->dsp, length,
+						    mixbuffer, members);
+			}
+		}
+	}
+
+	/* delete rx-data, increment buffers, change pointers */
+	list_for_each_entry(dsp, &dsp_ilist, list) {
+		if (dsp->hdlc)
+			continue;
+		p = dsp->rx_buff;
+		q = dsp->tx_buff;
+		r = dsp->rx_R;
+		/* move receive pointer when receiving */
+		if (!dsp->rx_is_off) {
+			rr = (r + length) & CMX_BUFF_MASK;
+			/* delete rx-data */
+			while (r != rr) {
+				p[r] = dsp_silence;
+				r = (r + 1) & CMX_BUFF_MASK;
+			}
+			/* increment rx-buffer pointer */
+			dsp->rx_R = r; /* write incremented read pointer */
+		}
+
+		/* check current rx_delay */
+		delay = (dsp->rx_W-dsp->rx_R) & CMX_BUFF_MASK;
+		if (delay >= CMX_BUFF_HALF)
+			delay = 0; /* will be the delay before next write */
+		/* check for lower delay */
+		if (delay < dsp->rx_delay[0])
+			dsp->rx_delay[0] = delay;
+		/* check current tx_delay */
+		delay = (dsp->tx_W-dsp->tx_R) & CMX_BUFF_MASK;
+		if (delay >= CMX_BUFF_HALF)
+			delay = 0; /* will be the delay before next write */
+		/* check for lower delay */
+		if (delay < dsp->tx_delay[0])
+			dsp->tx_delay[0] = delay;
+		if (jittercheck) {
+			/* find the lowest of all rx_delays */
+			delay = dsp->rx_delay[0];
+			i = 1;
+			while (i < MAX_SECONDS_JITTER_CHECK) {
+				if (delay > dsp->rx_delay[i])
+					delay = dsp->rx_delay[i];
+				i++;
+			}
+			/*
+			 * remove rx_delay only if we have delay AND we
+			 * have not preset cmx_delay AND
+			 * the delay is greater dsp_poll
+			 */
+			if (delay > dsp_poll && !dsp->cmx_delay) {
+				if (dsp_debug & DEBUG_DSP_CLOCK)
+					printk(KERN_DEBUG
+					       "%s lowest rx_delay of %d bytes for"
+					       " dsp %s are now removed.\n",
+					       __func__, delay,
+					       dsp->name);
+				r = dsp->rx_R;
+				rr = (r + delay - (dsp_poll >> 1))
+					& CMX_BUFF_MASK;
+				/* delete rx-data */
+				while (r != rr) {
+					p[r] = dsp_silence;
+					r = (r + 1) & CMX_BUFF_MASK;
+				}
+				/* increment rx-buffer pointer */
+				dsp->rx_R = r;
+				/* write incremented read pointer */
+			}
+			/* find the lowest of all tx_delays */
+			delay = dsp->tx_delay[0];
+			i = 1;
+			while (i < MAX_SECONDS_JITTER_CHECK) {
+				if (delay > dsp->tx_delay[i])
+					delay = dsp->tx_delay[i];
+				i++;
+			}
+			/*
+			 * remove delay only if we have delay AND we
+			 * have enabled tx_dejitter
+			 */
+			if (delay > dsp_poll && dsp->tx_dejitter) {
+				if (dsp_debug & DEBUG_DSP_CLOCK)
+					printk(KERN_DEBUG
+					       "%s lowest tx_delay of %d bytes for"
+					       " dsp %s are now removed.\n",
+					       __func__, delay,
+					       dsp->name);
+				r = dsp->tx_R;
+				rr = (r + delay - (dsp_poll >> 1))
+					& CMX_BUFF_MASK;
+				/* delete tx-data */
+				while (r != rr) {
+					q[r] = dsp_silence;
+					r = (r + 1) & CMX_BUFF_MASK;
+				}
+				/* increment rx-buffer pointer */
+				dsp->tx_R = r;
+				/* write incremented read pointer */
+			}
+			/* scroll up delays */
+			i = MAX_SECONDS_JITTER_CHECK - 1;
+			while (i) {
+				dsp->rx_delay[i] = dsp->rx_delay[i - 1];
+				dsp->tx_delay[i] = dsp->tx_delay[i - 1];
+				i--;
+			}
+			dsp->tx_delay[0] = CMX_BUFF_HALF; /* (infinite) delay */
+			dsp->rx_delay[0] = CMX_BUFF_HALF; /* (infinite) delay */
+		}
+	}
+
+	/* if next event would be in the past ... */
+	if ((s32)(dsp_spl_jiffies + dsp_tics-jiffies) <= 0)
+		dsp_spl_jiffies = jiffies + 1;
+	else
+		dsp_spl_jiffies += dsp_tics;
+
+	dsp_spl_tl.expires = dsp_spl_jiffies;
+	add_timer(&dsp_spl_tl);
+
+	/* unlock */
+	spin_unlock_irqrestore(&dsp_lock, flags);
+}
+
+/*
+ * audio data is transmitted from upper layer to the dsp
+ */
+void
+dsp_cmx_transmit(struct dsp *dsp, struct sk_buff *skb)
+{
+	u_int w, ww;
+	u8 *d, *p;
+	int space; /* todo: , l = skb->len; */
+#ifdef CMX_TX_DEBUG
+	char debugbuf[256] = "";
+#endif
+
+	/* check if there is enough space, and then copy */
+	w = dsp->tx_W;
+	ww = dsp->tx_R;
+	p = dsp->tx_buff;
+	d = skb->data;
+	space = (ww - w - 1) & CMX_BUFF_MASK;
+	/* write-pointer should not overrun nor reach read pointer */
+	if (space < skb->len) {
+		/* write to the space we have left */
+		ww = (ww - 1) & CMX_BUFF_MASK; /* end one byte prior tx_R */
+		if (dsp_debug & DEBUG_DSP_CLOCK)
+			printk(KERN_DEBUG "%s: TX overflow space=%d skb->len="
+			       "%d, w=0x%04x, ww=0x%04x\n", __func__, space,
+			       skb->len, w, ww);
+	} else
+		/* write until all byte are copied */
+		ww = (w + skb->len) & CMX_BUFF_MASK;
+	dsp->tx_W = ww;
+		/* show current buffer */
+#ifdef CMX_DEBUG
+	printk(KERN_DEBUG
+	       "cmx_transmit(dsp=%lx) %d bytes to 0x%x-0x%x. %s\n",
+	       (u_long)dsp, (ww - w) & CMX_BUFF_MASK, w, ww, dsp->name);
+#endif
+
+	/* copy transmit data to tx-buffer */
+#ifdef CMX_TX_DEBUG
+	sprintf(debugbuf, "TX getting (%04x-%04x)%p: ", w, ww, p);
+#endif
+	while (w != ww) {
+#ifdef CMX_TX_DEBUG
+		if (strlen(debugbuf) < 48)
+			sprintf(debugbuf + strlen(debugbuf), " %02x", *d);
+#endif
+		p[w] = *d++;
+		w = (w + 1) & CMX_BUFF_MASK;
+	}
+#ifdef CMX_TX_DEBUG
+	printk(KERN_DEBUG "%s\n", debugbuf);
+#endif
+
+}
+
+/*
+ * hdlc data is received from card and sent to all members.
+ */
+void
+dsp_cmx_hdlc(struct dsp *dsp, struct sk_buff *skb)
+{
+	struct sk_buff *nskb = NULL;
+	struct dsp_conf_member *member;
+	struct mISDNhead *hh;
+
+	/* not if not active */
+	if (!dsp->b_active)
+		return;
+
+	/* check if we have sompen */
+	if (skb->len < 1)
+		return;
+
+	/* no conf */
+	if (!dsp->conf) {
+		/* in case of software echo */
+		if (dsp->echo.software) {
+			nskb = skb_clone(skb, GFP_ATOMIC);
+			if (nskb) {
+				hh = mISDN_HEAD_P(nskb);
+				hh->prim = PH_DATA_REQ;
+				hh->id = 0;
+				skb_queue_tail(&dsp->sendq, nskb);
+				schedule_work(&dsp->workq);
+			}
+		}
+		return;
+	}
+	/* in case of hardware conference */
+	if (dsp->conf->hardware)
+		return;
+	list_for_each_entry(member, &dsp->conf->mlist, list) {
+		if (dsp->echo.software || member->dsp != dsp) {
+			nskb = skb_clone(skb, GFP_ATOMIC);
+			if (nskb) {
+				hh = mISDN_HEAD_P(nskb);
+				hh->prim = PH_DATA_REQ;
+				hh->id = 0;
+				skb_queue_tail(&member->dsp->sendq, nskb);
+				schedule_work(&member->dsp->workq);
+			}
+		}
+	}
+}