staging: echo: move to drivers/misc/

The code is clean, there are users of it, so it doesn't belong in
staging anymore, move it to drivers/misc/.

Cc: Steve Underwood <steveu@coppice.org>
Cc: David Rowe <david@rowetel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

9 files changed, 0 insertions, 1189 deletions

diff --git a/drivers/staging/Kconfig b/drivers/staging/Kconfig
index 40e5ca9..2ce3169 100644
--- a/drivers/staging/Kconfig
+++ b/drivers/staging/Kconfig
@@ -34,8 +34,6 @@ source "drivers/staging/winbond/Kconfig"
 
 source "drivers/staging/wlan-ng/Kconfig"
 
-source "drivers/staging/echo/Kconfig"
-
 source "drivers/staging/comedi/Kconfig"
 
 source "drivers/staging/olpc_dcon/Kconfig"
diff --git a/drivers/staging/Makefile b/drivers/staging/Makefile
index 00735bb..4d04090 100644
--- a/drivers/staging/Makefile
+++ b/drivers/staging/Makefile
@@ -9,7 +9,6 @@ obj-$(CONFIG_SLICOSS)		+= slicoss/
 obj-$(CONFIG_USBIP_CORE)	+= usbip/
 obj-$(CONFIG_W35UND)		+= winbond/
 obj-$(CONFIG_PRISM2_USB)	+= wlan-ng/
-obj-$(CONFIG_ECHO)		+= echo/
 obj-$(CONFIG_COMEDI)		+= comedi/
 obj-$(CONFIG_FB_OLPC_DCON)	+= olpc_dcon/
 obj-$(CONFIG_PANEL)		+= panel/
diff --git a/drivers/staging/echo/Kconfig b/drivers/staging/echo/Kconfig
deleted file mode 100644
index f1d41ea9..0000000
--- a/drivers/staging/echo/Kconfig
+++ /dev/null
@@ -1,9 +0,0 @@
-config ECHO
-	tristate "Line Echo Canceller support"
-	default n
-	---help---
-	  This driver provides line echo cancelling support for mISDN and
-	  Zaptel drivers.
-
-	  To compile this driver as a module, choose M here. The module
-	  will be called echo.
diff --git a/drivers/staging/echo/Makefile b/drivers/staging/echo/Makefile
deleted file mode 100644
index 7d4caac..0000000
--- a/drivers/staging/echo/Makefile
+++ /dev/null
@@ -1 +0,0 @@
-obj-$(CONFIG_ECHO) += echo.o
diff --git a/drivers/staging/echo/TODO b/drivers/staging/echo/TODO
deleted file mode 100644
index 72a311a..0000000
--- a/drivers/staging/echo/TODO
+++ /dev/null
@@ -1,5 +0,0 @@
-TODO:
-	- send to lkml for review
-
-Please send patches to Greg Kroah-Hartman <greg@kroah.com> and Cc: Steve
-Underwood <steveu@coppice.org> and David Rowe <david@rowetel.com>
diff --git a/drivers/staging/echo/echo.c b/drivers/staging/echo/echo.c
deleted file mode 100644
index 9597e95..0000000
--- a/drivers/staging/echo/echo.c
+++ /dev/null
@@ -1,674 +0,0 @@
-/*
- * SpanDSP - a series of DSP components for telephony
- *
- * echo.c - A line echo canceller.  This code is being developed
- *          against and partially complies with G168.
- *
- * Written by Steve Underwood <steveu@coppice.org>
- *         and David Rowe <david_at_rowetel_dot_com>
- *
- * Copyright (C) 2001, 2003 Steve Underwood, 2007 David Rowe
- *
- * Based on a bit from here, a bit from there, eye of toad, ear of
- * bat, 15 years of failed attempts by David and a few fried brain
- * cells.
- *
- * All rights reserved.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2, as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
- */
-
-/*! \file */
-
-/* Implementation Notes
-   David Rowe
-   April 2007
-
-   This code started life as Steve's NLMS algorithm with a tap
-   rotation algorithm to handle divergence during double talk.  I
-   added a Geigel Double Talk Detector (DTD) [2] and performed some
-   G168 tests.  However I had trouble meeting the G168 requirements,
-   especially for double talk - there were always cases where my DTD
-   failed, for example where near end speech was under the 6dB
-   threshold required for declaring double talk.
-
-   So I tried a two path algorithm [1], which has so far given better
-   results.  The original tap rotation/Geigel algorithm is available
-   in SVN http://svn.rowetel.com/software/oslec/tags/before_16bit.
-   It's probably possible to make it work if some one wants to put some
-   serious work into it.
-
-   At present no special treatment is provided for tones, which
-   generally cause NLMS algorithms to diverge.  Initial runs of a
-   subset of the G168 tests for tones (e.g ./echo_test 6) show the
-   current algorithm is passing OK, which is kind of surprising.  The
-   full set of tests needs to be performed to confirm this result.
-
-   One other interesting change is that I have managed to get the NLMS
-   code to work with 16 bit coefficients, rather than the original 32
-   bit coefficents.  This reduces the MIPs and storage required.
-   I evaulated the 16 bit port using g168_tests.sh and listening tests
-   on 4 real-world samples.
-
-   I also attempted the implementation of a block based NLMS update
-   [2] but although this passes g168_tests.sh it didn't converge well
-   on the real-world samples.  I have no idea why, perhaps a scaling
-   problem.  The block based code is also available in SVN
-   http://svn.rowetel.com/software/oslec/tags/before_16bit.  If this
-   code can be debugged, it will lead to further reduction in MIPS, as
-   the block update code maps nicely onto DSP instruction sets (it's a
-   dot product) compared to the current sample-by-sample update.
-
-   Steve also has some nice notes on echo cancellers in echo.h
-
-   References:
-
-   [1] Ochiai, Areseki, and Ogihara, "Echo Canceller with Two Echo
-       Path Models", IEEE Transactions on communications, COM-25,
-       No. 6, June
-       1977.
-       http://www.rowetel.com/images/echo/dual_path_paper.pdf
-
-   [2] The classic, very useful paper that tells you how to
-       actually build a real world echo canceller:
-	 Messerschmitt, Hedberg, Cole, Haoui, Winship, "Digital Voice
-	 Echo Canceller with a TMS320020,
-	 http://www.rowetel.com/images/echo/spra129.pdf
-
-   [3] I have written a series of blog posts on this work, here is
-       Part 1: http://www.rowetel.com/blog/?p=18
-
-   [4] The source code http://svn.rowetel.com/software/oslec/
-
-   [5] A nice reference on LMS filters:
-	 http://en.wikipedia.org/wiki/Least_mean_squares_filter
-
-   Credits:
-
-   Thanks to Steve Underwood, Jean-Marc Valin, and Ramakrishnan
-   Muthukrishnan for their suggestions and email discussions.  Thanks
-   also to those people who collected echo samples for me such as
-   Mark, Pawel, and Pavel.
-*/
-
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/slab.h>
-
-#include "echo.h"
-
-#define MIN_TX_POWER_FOR_ADAPTION	64
-#define MIN_RX_POWER_FOR_ADAPTION	64
-#define DTD_HANGOVER			600	/* 600 samples, or 75ms     */
-#define DC_LOG2BETA			3	/* log2() of DC filter Beta */
-
-/* adapting coeffs using the traditional stochastic descent (N)LMS algorithm */
-
-#ifdef __bfin__
-static inline void lms_adapt_bg(struct oslec_state *ec, int clean, int shift)
-{
-	int i;
-	int offset1;
-	int offset2;
-	int factor;
-	int exp;
-	int16_t *phist;
-	int n;
-
-	if (shift > 0)
-		factor = clean << shift;
-	else
-		factor = clean >> -shift;
-
-	/* Update the FIR taps */
-
-	offset2 = ec->curr_pos;
-	offset1 = ec->taps - offset2;
-	phist = &ec->fir_state_bg.history[offset2];
-
-	/* st: and en: help us locate the assembler in echo.s */
-
-	/* asm("st:"); */
-	n = ec->taps;
-	for (i = 0; i < n; i++) {
-		exp = *phist++ * factor;
-		ec->fir_taps16[1][i] += (int16_t) ((exp + (1 << 14)) >> 15);
-	}
-	/* asm("en:"); */
-
-	/* Note the asm for the inner loop above generated by Blackfin gcc
-	   4.1.1 is pretty good (note even parallel instructions used):
-
-	   R0 = W [P0++] (X);
-	   R0 *= R2;
-	   R0 = R0 + R3 (NS) ||
-	   R1 = W [P1] (X) ||
-	   nop;
-	   R0 >>>= 15;
-	   R0 = R0 + R1;
-	   W [P1++] = R0;
-
-	   A block based update algorithm would be much faster but the
-	   above can't be improved on much.  Every instruction saved in
-	   the loop above is 2 MIPs/ch!  The for loop above is where the
-	   Blackfin spends most of it's time - about 17 MIPs/ch measured
-	   with speedtest.c with 256 taps (32ms).  Write-back and
-	   Write-through cache gave about the same performance.
-	 */
-}
-
-/*
-   IDEAS for further optimisation of lms_adapt_bg():
-
-   1/ The rounding is quite costly.  Could we keep as 32 bit coeffs
-   then make filter pluck the MS 16-bits of the coeffs when filtering?
-   However this would lower potential optimisation of filter, as I
-   think the dual-MAC architecture requires packed 16 bit coeffs.
-
-   2/ Block based update would be more efficient, as per comments above,
-   could use dual MAC architecture.
-
-   3/ Look for same sample Blackfin LMS code, see if we can get dual-MAC
-   packing.
-
-   4/ Execute the whole e/c in a block of say 20ms rather than sample
-   by sample.  Processing a few samples every ms is inefficient.
-*/
-
-#else
-static inline void lms_adapt_bg(struct oslec_state *ec, int clean, int shift)
-{
-	int i;
-
-	int offset1;
-	int offset2;
-	int factor;
-	int exp;
-
-	if (shift > 0)
-		factor = clean << shift;
-	else
-		factor = clean >> -shift;
-
-	/* Update the FIR taps */
-
-	offset2 = ec->curr_pos;
-	offset1 = ec->taps - offset2;
-
-	for (i = ec->taps - 1; i >= offset1; i--) {
-		exp = (ec->fir_state_bg.history[i - offset1] * factor);
-		ec->fir_taps16[1][i] += (int16_t) ((exp + (1 << 14)) >> 15);
-	}
-	for (; i >= 0; i--) {
-		exp = (ec->fir_state_bg.history[i + offset2] * factor);
-		ec->fir_taps16[1][i] += (int16_t) ((exp + (1 << 14)) >> 15);
-	}
-}
-#endif
-
-static inline int top_bit(unsigned int bits)
-{
-	if (bits == 0)
-		return -1;
-	else
-		return (int)fls((int32_t) bits) - 1;
-}
-
-struct oslec_state *oslec_create(int len, int adaption_mode)
-{
-	struct oslec_state *ec;
-	int i;
-	const int16_t *history;
-
-	ec = kzalloc(sizeof(*ec), GFP_KERNEL);
-	if (!ec)
-		return NULL;
-
-	ec->taps = len;
-	ec->log2taps = top_bit(len);
-	ec->curr_pos = ec->taps - 1;
-
-	ec->fir_taps16[0] =
-	    kcalloc(ec->taps, sizeof(int16_t), GFP_KERNEL);
-	if (!ec->fir_taps16[0])
-		goto error_oom_0;
-
-	ec->fir_taps16[1] =
-	    kcalloc(ec->taps, sizeof(int16_t), GFP_KERNEL);
-	if (!ec->fir_taps16[1])
-		goto error_oom_1;
-
-	history = fir16_create(&ec->fir_state, ec->fir_taps16[0], ec->taps);
-	if (!history)
-		goto error_state;
-	history = fir16_create(&ec->fir_state_bg, ec->fir_taps16[1], ec->taps);
-	if (!history)
-		goto error_state_bg;
-
-	for (i = 0; i < 5; i++)
-		ec->xvtx[i] = ec->yvtx[i] = ec->xvrx[i] = ec->yvrx[i] = 0;
-
-	ec->cng_level = 1000;
-	oslec_adaption_mode(ec, adaption_mode);
-
-	ec->snapshot = kcalloc(ec->taps, sizeof(int16_t), GFP_KERNEL);
-	if (!ec->snapshot)
-		goto error_snap;
-
-	ec->cond_met = 0;
-	ec->pstates = 0;
-	ec->ltxacc = ec->lrxacc = ec->lcleanacc = ec->lclean_bgacc = 0;
-	ec->ltx = ec->lrx = ec->lclean = ec->lclean_bg = 0;
-	ec->tx_1 = ec->tx_2 = ec->rx_1 = ec->rx_2 = 0;
-	ec->lbgn = ec->lbgn_acc = 0;
-	ec->lbgn_upper = 200;
-	ec->lbgn_upper_acc = ec->lbgn_upper << 13;
-
-	return ec;
-
-error_snap:
-	fir16_free(&ec->fir_state_bg);
-error_state_bg:
-	fir16_free(&ec->fir_state);
-error_state:
-	kfree(ec->fir_taps16[1]);
-error_oom_1:
-	kfree(ec->fir_taps16[0]);
-error_oom_0:
-	kfree(ec);
-	return NULL;
-}
-EXPORT_SYMBOL_GPL(oslec_create);
-
-void oslec_free(struct oslec_state *ec)
-{
-	int i;
-
-	fir16_free(&ec->fir_state);
-	fir16_free(&ec->fir_state_bg);
-	for (i = 0; i < 2; i++)
-		kfree(ec->fir_taps16[i]);
-	kfree(ec->snapshot);
-	kfree(ec);
-}
-EXPORT_SYMBOL_GPL(oslec_free);
-
-void oslec_adaption_mode(struct oslec_state *ec, int adaption_mode)
-{
-	ec->adaption_mode = adaption_mode;
-}
-EXPORT_SYMBOL_GPL(oslec_adaption_mode);
-
-void oslec_flush(struct oslec_state *ec)
-{
-	int i;
-
-	ec->ltxacc = ec->lrxacc = ec->lcleanacc = ec->lclean_bgacc = 0;
-	ec->ltx = ec->lrx = ec->lclean = ec->lclean_bg = 0;
-	ec->tx_1 = ec->tx_2 = ec->rx_1 = ec->rx_2 = 0;
-
-	ec->lbgn = ec->lbgn_acc = 0;
-	ec->lbgn_upper = 200;
-	ec->lbgn_upper_acc = ec->lbgn_upper << 13;
-
-	ec->nonupdate_dwell = 0;
-
-	fir16_flush(&ec->fir_state);
-	fir16_flush(&ec->fir_state_bg);
-	ec->fir_state.curr_pos = ec->taps - 1;
-	ec->fir_state_bg.curr_pos = ec->taps - 1;
-	for (i = 0; i < 2; i++)
-		memset(ec->fir_taps16[i], 0, ec->taps * sizeof(int16_t));
-
-	ec->curr_pos = ec->taps - 1;
-	ec->pstates = 0;
-}
-EXPORT_SYMBOL_GPL(oslec_flush);
-
-void oslec_snapshot(struct oslec_state *ec)
-{
-	memcpy(ec->snapshot, ec->fir_taps16[0], ec->taps * sizeof(int16_t));
-}
-EXPORT_SYMBOL_GPL(oslec_snapshot);
-
-/* Dual Path Echo Canceller */
-
-int16_t oslec_update(struct oslec_state *ec, int16_t tx, int16_t rx)
-{
-	int32_t echo_value;
-	int clean_bg;
-	int tmp;
-	int tmp1;
-
-	/*
-	 * Input scaling was found be required to prevent problems when tx
-	 * starts clipping.  Another possible way to handle this would be the
-	 * filter coefficent scaling.
-	 */
-
-	ec->tx = tx;
-	ec->rx = rx;
-	tx >>= 1;
-	rx >>= 1;
-
-	/*
-	 * Filter DC, 3dB point is 160Hz (I think), note 32 bit precision
-	 * required otherwise values do not track down to 0. Zero at DC, Pole
-	 * at (1-Beta) on real axis.  Some chip sets (like Si labs) don't
-	 * need this, but something like a $10 X100P card does.  Any DC really
-	 * slows down convergence.
-	 *
-	 * Note: removes some low frequency from the signal, this reduces the
-	 * speech quality when listening to samples through headphones but may
-	 * not be obvious through a telephone handset.
-	 *
-	 * Note that the 3dB frequency in radians is approx Beta, e.g. for Beta
-	 * = 2^(-3) = 0.125, 3dB freq is 0.125 rads = 159Hz.
-	 */
-
-	if (ec->adaption_mode & ECHO_CAN_USE_RX_HPF) {
-		tmp = rx << 15;
-
-		/*
-		 * Make sure the gain of the HPF is 1.0. This can still
-		 * saturate a little under impulse conditions, and it might
-		 * roll to 32768 and need clipping on sustained peak level
-		 * signals. However, the scale of such clipping is small, and
-		 * the error due to any saturation should not markedly affect
-		 * the downstream processing.
-		 */
-		tmp -= (tmp >> 4);
-
-		ec->rx_1 += -(ec->rx_1 >> DC_LOG2BETA) + tmp - ec->rx_2;
-
-		/*
-		 * hard limit filter to prevent clipping.  Note that at this
-		 * stage rx should be limited to +/- 16383 due to right shift
-		 * above
-		 */
-		tmp1 = ec->rx_1 >> 15;
-		if (tmp1 > 16383)
-			tmp1 = 16383;
-		if (tmp1 < -16383)
-			tmp1 = -16383;
-		rx = tmp1;
-		ec->rx_2 = tmp;
-	}
-
-	/* Block average of power in the filter states.  Used for
-	   adaption power calculation. */
-
-	{
-		int new, old;
-
-		/* efficient "out with the old and in with the new" algorithm so
-		   we don't have to recalculate over the whole block of
-		   samples. */
-		new = (int)tx * (int)tx;
-		old = (int)ec->fir_state.history[ec->fir_state.curr_pos] *
-		    (int)ec->fir_state.history[ec->fir_state.curr_pos];
-		ec->pstates +=
-		    ((new - old) + (1 << (ec->log2taps - 1))) >> ec->log2taps;
-		if (ec->pstates < 0)
-			ec->pstates = 0;
-	}
-
-	/* Calculate short term average levels using simple single pole IIRs */
-
-	ec->ltxacc += abs(tx) - ec->ltx;
-	ec->ltx = (ec->ltxacc + (1 << 4)) >> 5;
-	ec->lrxacc += abs(rx) - ec->lrx;
-	ec->lrx = (ec->lrxacc + (1 << 4)) >> 5;
-
-	/* Foreground filter */
-
-	ec->fir_state.coeffs = ec->fir_taps16[0];
-	echo_value = fir16(&ec->fir_state, tx);
-	ec->clean = rx - echo_value;
-	ec->lcleanacc += abs(ec->clean) - ec->lclean;
-	ec->lclean = (ec->lcleanacc + (1 << 4)) >> 5;
-
-	/* Background filter */
-
-	echo_value = fir16(&ec->fir_state_bg, tx);
-	clean_bg = rx - echo_value;
-	ec->lclean_bgacc += abs(clean_bg) - ec->lclean_bg;
-	ec->lclean_bg = (ec->lclean_bgacc + (1 << 4)) >> 5;
-
-	/* Background Filter adaption */
-
-	/* Almost always adap bg filter, just simple DT and energy
-	   detection to minimise adaption in cases of strong double talk.
-	   However this is not critical for the dual path algorithm.
-	 */
-	ec->factor = 0;
-	ec->shift = 0;
-	if ((ec->nonupdate_dwell == 0)) {
-		int p, logp, shift;
-
-		/* Determine:
-
-		   f = Beta * clean_bg_rx/P ------ (1)
-
-		   where P is the total power in the filter states.
-
-		   The Boffins have shown that if we obey (1) we converge
-		   quickly and avoid instability.
-
-		   The correct factor f must be in Q30, as this is the fixed
-		   point format required by the lms_adapt_bg() function,
-		   therefore the scaled version of (1) is:
-
-		   (2^30) * f  = (2^30) * Beta * clean_bg_rx/P
-		   factor      = (2^30) * Beta * clean_bg_rx/P     ----- (2)
-
-		   We have chosen Beta = 0.25 by experiment, so:
-
-		   factor      = (2^30) * (2^-2) * clean_bg_rx/P
-
-		   (30 - 2 - log2(P))
-		   factor      = clean_bg_rx 2                     ----- (3)
-
-		   To avoid a divide we approximate log2(P) as top_bit(P),
-		   which returns the position of the highest non-zero bit in
-		   P.  This approximation introduces an error as large as a
-		   factor of 2, but the algorithm seems to handle it OK.
-
-		   Come to think of it a divide may not be a big deal on a
-		   modern DSP, so its probably worth checking out the cycles
-		   for a divide versus a top_bit() implementation.
-		 */
-
-		p = MIN_TX_POWER_FOR_ADAPTION + ec->pstates;
-		logp = top_bit(p) + ec->log2taps;
-		shift = 30 - 2 - logp;
-		ec->shift = shift;
-
-		lms_adapt_bg(ec, clean_bg, shift);
-	}
-
-	/* very simple DTD to make sure we dont try and adapt with strong
-	   near end speech */
-
-	ec->adapt = 0;
-	if ((ec->lrx > MIN_RX_POWER_FOR_ADAPTION) && (ec->lrx > ec->ltx))
-		ec->nonupdate_dwell = DTD_HANGOVER;
-	if (ec->nonupdate_dwell)
-		ec->nonupdate_dwell--;
-
-	/* Transfer logic */
-
-	/* These conditions are from the dual path paper [1], I messed with
-	   them a bit to improve performance. */
-
-	if ((ec->adaption_mode & ECHO_CAN_USE_ADAPTION) &&
-	    (ec->nonupdate_dwell == 0) &&
-	    /* (ec->Lclean_bg < 0.875*ec->Lclean) */
-	    (8 * ec->lclean_bg < 7 * ec->lclean) &&
-	    /* (ec->Lclean_bg < 0.125*ec->Ltx) */
-	    (8 * ec->lclean_bg < ec->ltx)) {
-		if (ec->cond_met == 6) {
-			/*
-			 * BG filter has had better results for 6 consecutive
-			 * samples
-			 */
-			ec->adapt = 1;
-			memcpy(ec->fir_taps16[0], ec->fir_taps16[1],
-			       ec->taps * sizeof(int16_t));
-		} else
-			ec->cond_met++;
-	} else
-		ec->cond_met = 0;
-
-	/* Non-Linear Processing */
-
-	ec->clean_nlp = ec->clean;
-	if (ec->adaption_mode & ECHO_CAN_USE_NLP) {
-		/*
-		 * Non-linear processor - a fancy way to say "zap small
-		 * signals, to avoid residual echo due to (uLaw/ALaw)
-		 * non-linearity in the channel.".
-		 */
-
-		if ((16 * ec->lclean < ec->ltx)) {
-			/*
-			 * Our e/c has improved echo by at least 24 dB (each
-			 * factor of 2 is 6dB, so 2*2*2*2=16 is the same as
-			 * 6+6+6+6=24dB)
-			 */
-			if (ec->adaption_mode & ECHO_CAN_USE_CNG) {
-				ec->cng_level = ec->lbgn;
-
-				/*
-				 * Very elementary comfort noise generation.
-				 * Just random numbers rolled off very vaguely
-				 * Hoth-like.  DR: This noise doesn't sound
-				 * quite right to me - I suspect there are some
-				 * overflow issues in the filtering as it's too
-				 * "crackly".
-				 * TODO: debug this, maybe just play noise at
-				 * high level or look at spectrum.
-				 */
-
-				ec->cng_rndnum =
-				    1664525U * ec->cng_rndnum + 1013904223U;
-				ec->cng_filter =
-				    ((ec->cng_rndnum & 0xFFFF) - 32768 +
-				     5 * ec->cng_filter) >> 3;
-				ec->clean_nlp =
-				    (ec->cng_filter * ec->cng_level * 8) >> 14;
-
-			} else if (ec->adaption_mode & ECHO_CAN_USE_CLIP) {
-				/* This sounds much better than CNG */
-				if (ec->clean_nlp > ec->lbgn)
-					ec->clean_nlp = ec->lbgn;
-				if (ec->clean_nlp < -ec->lbgn)
-					ec->clean_nlp = -ec->lbgn;
-			} else {
-				/*
-				 * just mute the residual, doesn't sound very
-				 * good, used mainly in G168 tests
-				 */
-				ec->clean_nlp = 0;
-			}
-		} else {
-			/*
-			 * Background noise estimator.  I tried a few
-			 * algorithms here without much luck.  This very simple
-			 * one seems to work best, we just average the level
-			 * using a slow (1 sec time const) filter if the
-			 * current level is less than a (experimentally
-			 * derived) constant.  This means we dont include high
-			 * level signals like near end speech.  When combined
-			 * with CNG or especially CLIP seems to work OK.
-			 */
-			if (ec->lclean < 40) {
-				ec->lbgn_acc += abs(ec->clean) - ec->lbgn;
-				ec->lbgn = (ec->lbgn_acc + (1 << 11)) >> 12;
-			}
-		}
-	}
-
-	/* Roll around the taps buffer */
-	if (ec->curr_pos <= 0)
-		ec->curr_pos = ec->taps;
-	ec->curr_pos--;
-
-	if (ec->adaption_mode & ECHO_CAN_DISABLE)
-		ec->clean_nlp = rx;
-
-	/* Output scaled back up again to match input scaling */
-
-	return (int16_t) ec->clean_nlp << 1;
-}
-EXPORT_SYMBOL_GPL(oslec_update);
-
-/* This function is separated from the echo canceller is it is usually called
-   as part of the tx process.  See rx HP (DC blocking) filter above, it's
-   the same design.
-
-   Some soft phones send speech signals with a lot of low frequency
-   energy, e.g. down to 20Hz.  This can make the hybrid non-linear
-   which causes the echo canceller to fall over.  This filter can help
-   by removing any low frequency before it gets to the tx port of the
-   hybrid.
-
-   It can also help by removing and DC in the tx signal.  DC is bad
-   for LMS algorithms.
-
-   This is one of the classic DC removal filters, adjusted to provide
-   sufficient bass rolloff to meet the above requirement to protect hybrids
-   from things that upset them. The difference between successive samples
-   produces a lousy HPF, and then a suitably placed pole flattens things out.
-   The final result is a nicely rolled off bass end. The filtering is
-   implemented with extended fractional precision, which noise shapes things,
-   giving very clean DC removal.
-*/
-
-int16_t oslec_hpf_tx(struct oslec_state *ec, int16_t tx)
-{
-	int tmp;
-	int tmp1;
-
-	if (ec->adaption_mode & ECHO_CAN_USE_TX_HPF) {
-		tmp = tx << 15;
-
-		/*
-		 * Make sure the gain of the HPF is 1.0. The first can still
-		 * saturate a little under impulse conditions, and it might
-		 * roll to 32768 and need clipping on sustained peak level
-		 * signals. However, the scale of such clipping is small, and
-		 * the error due to any saturation should not markedly affect
-		 * the downstream processing.
-		 */
-		tmp -= (tmp >> 4);
-
-		ec->tx_1 += -(ec->tx_1 >> DC_LOG2BETA) + tmp - ec->tx_2;
-		tmp1 = ec->tx_1 >> 15;
-		if (tmp1 > 32767)
-			tmp1 = 32767;
-		if (tmp1 < -32767)
-			tmp1 = -32767;
-		tx = tmp1;
-		ec->tx_2 = tmp;
-	}
-
-	return tx;
-}
-EXPORT_SYMBOL_GPL(oslec_hpf_tx);
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("David Rowe");
-MODULE_DESCRIPTION("Open Source Line Echo Canceller");
-MODULE_VERSION("0.3.0");
diff --git a/drivers/staging/echo/echo.h b/drivers/staging/echo/echo.h
deleted file mode 100644
index 9b08c63..0000000
--- a/drivers/staging/echo/echo.h
+++ /dev/null
@@ -1,187 +0,0 @@
-/*
- * SpanDSP - a series of DSP components for telephony
- *
- * echo.c - A line echo canceller.  This code is being developed
- *          against and partially complies with G168.
- *
- * Written by Steve Underwood <steveu@coppice.org>
- *         and David Rowe <david_at_rowetel_dot_com>
- *
- * Copyright (C) 2001 Steve Underwood and 2007 David Rowe
- *
- * All rights reserved.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2, as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
- */
-
-#ifndef __ECHO_H
-#define __ECHO_H
-
-/*
-Line echo cancellation for voice
-
-What does it do?
-
-This module aims to provide G.168-2002 compliant echo cancellation, to remove
-electrical echoes (e.g. from 2-4 wire hybrids) from voice calls.
-
-How does it work?
-
-The heart of the echo cancellor is FIR filter. This is adapted to match the
-echo impulse response of the telephone line. It must be long enough to
-adequately cover the duration of that impulse response. The signal transmitted
-to the telephone line is passed through the FIR filter. Once the FIR is
-properly adapted, the resulting output is an estimate of the echo signal
-received from the line. This is subtracted from the received signal. The result
-is an estimate of the signal which originated at the far end of the line, free
-from echos of our own transmitted signal.
-
-The least mean squares (LMS) algorithm is attributed to Widrow and Hoff, and
-was introduced in 1960. It is the commonest form of filter adaption used in
-things like modem line equalisers and line echo cancellers. There it works very
-well.  However, it only works well for signals of constant amplitude. It works
-very poorly for things like speech echo cancellation, where the signal level
-varies widely.  This is quite easy to fix. If the signal level is normalised -
-similar to applying AGC - LMS can work as well for a signal of varying
-amplitude as it does for a modem signal. This normalised least mean squares
-(NLMS) algorithm is the commonest one used for speech echo cancellation. Many
-other algorithms exist - e.g. RLS (essentially the same as Kalman filtering),
-FAP, etc. Some perform significantly better than NLMS.  However, factors such
-as computational complexity and patents favour the use of NLMS.
-
-A simple refinement to NLMS can improve its performance with speech. NLMS tends
-to adapt best to the strongest parts of a signal. If the signal is white noise,
-the NLMS algorithm works very well. However, speech has more low frequency than
-high frequency content. Pre-whitening (i.e. filtering the signal to flatten its
-spectrum) the echo signal improves the adapt rate for speech, and ensures the
-final residual signal is not heavily biased towards high frequencies. A very
-low complexity filter is adequate for this, so pre-whitening adds little to the
-compute requirements of the echo canceller.
-
-An FIR filter adapted using pre-whitened NLMS performs well, provided certain
-conditions are met:
-
-    - The transmitted signal has poor self-correlation.
-    - There is no signal being generated within the environment being
-      cancelled.
-
-The difficulty is that neither of these can be guaranteed.
-
-If the adaption is performed while transmitting noise (or something fairly
-noise like, such as voice) the adaption works very well. If the adaption is
-performed while transmitting something highly correlative (typically narrow
-band energy such as signalling tones or DTMF), the adaption can go seriously
-wrong. The reason is there is only one solution for the adaption on a near
-random signal - the impulse response of the line. For a repetitive signal,
-there are any number of solutions which converge the adaption, and nothing
-guides the adaption to choose the generalised one. Allowing an untrained
-canceller to converge on this kind of narrowband energy probably a good thing,
-since at least it cancels the tones. Allowing a well converged canceller to
-continue converging on such energy is just a way to ruin its generalised
-adaption. A narrowband detector is needed, so adapation can be suspended at
-appropriate times.
-
-The adaption process is based on trying to eliminate the received signal. When
-there is any signal from within the environment being cancelled it may upset
-the adaption process. Similarly, if the signal we are transmitting is small,
-noise may dominate and disturb the adaption process. If we can ensure that the
-adaption is only performed when we are transmitting a significant signal level,
-and the environment is not, things will be OK. Clearly, it is easy to tell when
-we are sending a significant signal. Telling, if the environment is generating
-a significant signal, and doing it with sufficient speed that the adaption will
-not have diverged too much more we stop it, is a little harder.
-
-The key problem in detecting when the environment is sourcing significant
-energy is that we must do this very quickly. Given a reasonably long sample of
-the received signal, there are a number of strategies which may be used to
-assess whether that signal contains a strong far end component. However, by the
-time that assessment is complete the far end signal will have already caused
-major mis-convergence in the adaption process. An assessment algorithm is
-needed which produces a fairly accurate result from a very short burst of far
-end energy.
-
-How do I use it?
-
-The echo cancellor processes both the transmit and receive streams sample by
-sample. The processing function is not declared inline. Unfortunately,
-cancellation requires many operations per sample, so the call overhead is only
-a minor burden.
-*/
-
-#include "fir.h"
-#include "oslec.h"
-
-/*
-    G.168 echo canceller descriptor. This defines the working state for a line
-    echo canceller.
-*/
-struct oslec_state {
-	int16_t tx;
-	int16_t rx;
-	int16_t clean;
-	int16_t clean_nlp;
-
-	int nonupdate_dwell;
-	int curr_pos;
-	int taps;
-	int log2taps;
-	int adaption_mode;
-
-	int cond_met;
-	int32_t pstates;
-	int16_t adapt;
-	int32_t factor;
-	int16_t shift;
-
-	/* Average levels and averaging filter states */
-	int ltxacc;
-	int lrxacc;
-	int lcleanacc;
-	int lclean_bgacc;
-	int ltx;
-	int lrx;
-	int lclean;
-	int lclean_bg;
-	int lbgn;
-	int lbgn_acc;
-	int lbgn_upper;
-	int lbgn_upper_acc;
-
-	/* foreground and background filter states */
-	struct fir16_state_t fir_state;
-	struct fir16_state_t fir_state_bg;
-	int16_t *fir_taps16[2];
-
-	/* DC blocking filter states */
-	int tx_1;
-	int tx_2;
-	int rx_1;
-	int rx_2;
-
-	/* optional High Pass Filter states */
-	int32_t xvtx[5];
-	int32_t yvtx[5];
-	int32_t xvrx[5];
-	int32_t yvrx[5];
-
-	/* Parameters for the optional Hoth noise generator */
-	int cng_level;
-	int cng_rndnum;
-	int cng_filter;
-
-	/* snapshot sample of coeffs used for development */
-	int16_t *snapshot;
-};
-
-#endif /* __ECHO_H */
diff --git a/drivers/staging/echo/fir.h b/drivers/staging/echo/fir.h
deleted file mode 100644
index 7b9fabf..0000000
--- a/drivers/staging/echo/fir.h
+++ /dev/null
@@ -1,216 +0,0 @@
-/*
- * SpanDSP - a series of DSP components for telephony
- *
- * fir.h - General telephony FIR routines
- *
- * Written by Steve Underwood <steveu@coppice.org>
- *
- * Copyright (C) 2002 Steve Underwood
- *
- * All rights reserved.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2, as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
- */
-
-#if !defined(_FIR_H_)
-#define _FIR_H_
-
-/*
-   Blackfin NOTES & IDEAS:
-
-   A simple dot product function is used to implement the filter.  This performs
-   just one MAC/cycle which is inefficient but was easy to implement as a first
-   pass.  The current Blackfin code also uses an unrolled form of the filter
-   history to avoid 0 length hardware loop issues.  This is wasteful of
-   memory.
-
-   Ideas for improvement:
-
-   1/ Rewrite filter for dual MAC inner loop.  The issue here is handling
-   history sample offsets that are 16 bit aligned - the dual MAC needs
-   32 bit aligmnent.  There are some good examples in libbfdsp.
-
-   2/ Use the hardware circular buffer facility tohalve memory usage.
-
-   3/ Consider using internal memory.
-
-   Using less memory might also improve speed as cache misses will be
-   reduced. A drop in MIPs and memory approaching 50% should be
-   possible.
-
-   The foreground and background filters currenlty use a total of
-   about 10 MIPs/ch as measured with speedtest.c on a 256 TAP echo
-   can.
-*/
-
-/*
- * 16 bit integer FIR descriptor. This defines the working state for a single
- * instance of an FIR filter using 16 bit integer coefficients.
- */
-struct fir16_state_t {
-	int taps;
-	int curr_pos;
-	const int16_t *coeffs;
-	int16_t *history;
-};
-
-/*
- * 32 bit integer FIR descriptor. This defines the working state for a single
- * instance of an FIR filter using 32 bit integer coefficients, and filtering
- * 16 bit integer data.
- */
-struct fir32_state_t {
-	int taps;
-	int curr_pos;
-	const int32_t *coeffs;
-	int16_t *history;
-};
-
-/*
- * Floating point FIR descriptor. This defines the working state for a single
- * instance of an FIR filter using floating point coefficients and data.
- */
-struct fir_float_state_t {
-	int taps;
-	int curr_pos;
-	const float *coeffs;
-	float *history;
-};
-
-static inline const int16_t *fir16_create(struct fir16_state_t *fir,
-					      const int16_t *coeffs, int taps)
-{
-	fir->taps = taps;
-	fir->curr_pos = taps - 1;
-	fir->coeffs = coeffs;
-#if defined(__bfin__)
-	fir->history = kcalloc(2 * taps, sizeof(int16_t), GFP_KERNEL);
-#else
-	fir->history = kcalloc(taps, sizeof(int16_t), GFP_KERNEL);
-#endif
-	return fir->history;
-}
-
-static inline void fir16_flush(struct fir16_state_t *fir)
-{
-#if defined(__bfin__)
-	memset(fir->history, 0, 2 * fir->taps * sizeof(int16_t));
-#else
-	memset(fir->history, 0, fir->taps * sizeof(int16_t));
-#endif
-}
-
-static inline void fir16_free(struct fir16_state_t *fir)
-{
-	kfree(fir->history);
-}
-
-#ifdef __bfin__
-static inline int32_t dot_asm(short *x, short *y, int len)
-{
-	int dot;
-
-	len--;
-
-	__asm__("I0 = %1;\n\t"
-		"I1 = %2;\n\t"
-		"A0 = 0;\n\t"
-		"R0.L = W[I0++] || R1.L = W[I1++];\n\t"
-		"LOOP dot%= LC0 = %3;\n\t"
-		"LOOP_BEGIN dot%=;\n\t"
-		"A0 += R0.L * R1.L (IS) || R0.L = W[I0++] || R1.L = W[I1++];\n\t"
-		"LOOP_END dot%=;\n\t"
-		"A0 += R0.L*R1.L (IS);\n\t"
-		"R0 = A0;\n\t"
-		"%0 = R0;\n\t"
-		: "=&d"(dot)
-		: "a"(x), "a"(y), "a"(len)
-		: "I0", "I1", "A1", "A0", "R0", "R1"
-	);
-
-	return dot;
-}
-#endif
-
-static inline int16_t fir16(struct fir16_state_t *fir, int16_t sample)
-{
-	int32_t y;
-#if defined(__bfin__)
-	fir->history[fir->curr_pos] = sample;
-	fir->history[fir->curr_pos + fir->taps] = sample;
-	y = dot_asm((int16_t *) fir->coeffs, &fir->history[fir->curr_pos],
-		    fir->taps);
-#else
-	int i;
-	int offset1;
-	int offset2;
-
-	fir->history[fir->curr_pos] = sample;
-
-	offset2 = fir->curr_pos;
-	offset1 = fir->taps - offset2;
-	y = 0;
-	for (i = fir->taps - 1; i >= offset1; i--)
-		y += fir->coeffs[i] * fir->history[i - offset1];
-	for (; i >= 0; i--)
-		y += fir->coeffs[i] * fir->history[i + offset2];
-#endif
-	if (fir->curr_pos <= 0)
-		fir->curr_pos = fir->taps;
-	fir->curr_pos--;
-	return (int16_t) (y >> 15);
-}
-
-static inline const int16_t *fir32_create(struct fir32_state_t *fir,
-					      const int32_t *coeffs, int taps)
-{
-	fir->taps = taps;
-	fir->curr_pos = taps - 1;
-	fir->coeffs = coeffs;
-	fir->history = kcalloc(taps, sizeof(int16_t), GFP_KERNEL);
-	return fir->history;
-}
-
-static inline void fir32_flush(struct fir32_state_t *fir)
-{
-	memset(fir->history, 0, fir->taps * sizeof(int16_t));
-}
-
-static inline void fir32_free(struct fir32_state_t *fir)
-{
-	kfree(fir->history);
-}
-
-static inline int16_t fir32(struct fir32_state_t *fir, int16_t sample)
-{
-	int i;
-	int32_t y;
-	int offset1;
-	int offset2;
-
-	fir->history[fir->curr_pos] = sample;
-	offset2 = fir->curr_pos;
-	offset1 = fir->taps - offset2;
-	y = 0;
-	for (i = fir->taps - 1; i >= offset1; i--)
-		y += fir->coeffs[i] * fir->history[i - offset1];
-	for (; i >= 0; i--)
-		y += fir->coeffs[i] * fir->history[i + offset2];
-	if (fir->curr_pos <= 0)
-		fir->curr_pos = fir->taps;
-	fir->curr_pos--;
-	return (int16_t) (y >> 15);
-}
-
-#endif
diff --git a/drivers/staging/echo/oslec.h b/drivers/staging/echo/oslec.h
deleted file mode 100644
index f417536..0000000
--- a/drivers/staging/echo/oslec.h
+++ /dev/null
@@ -1,94 +0,0 @@
-/*
- *  OSLEC - A line echo canceller.  This code is being developed
- *          against and partially complies with G168. Using code from SpanDSP
- *
- * Written by Steve Underwood <steveu@coppice.org>
- *         and David Rowe <david_at_rowetel_dot_com>
- *
- * Copyright (C) 2001 Steve Underwood and 2007-2008 David Rowe
- *
- * All rights reserved.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2, as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
- *
- */
-
-#ifndef __OSLEC_H
-#define __OSLEC_H
-
-/* Mask bits for the adaption mode */
-#define ECHO_CAN_USE_ADAPTION	0x01
-#define ECHO_CAN_USE_NLP	0x02
-#define ECHO_CAN_USE_CNG	0x04
-#define ECHO_CAN_USE_CLIP	0x08
-#define ECHO_CAN_USE_TX_HPF	0x10
-#define ECHO_CAN_USE_RX_HPF	0x20
-#define ECHO_CAN_DISABLE	0x40
-
-/**
- * oslec_state: G.168 echo canceller descriptor.
- *
- * This defines the working state for a line echo canceller.
- */
-struct oslec_state;
-
-/**
- * oslec_create - Create a voice echo canceller context.
- * @len: The length of the canceller, in samples.
- * @return: The new canceller context, or NULL if the canceller could not be
- * created.
- */
-struct oslec_state *oslec_create(int len, int adaption_mode);
-
-/**
- * oslec_free - Free a voice echo canceller context.
- * @ec: The echo canceller context.
- */
-void oslec_free(struct oslec_state *ec);
-
-/**
- * oslec_flush - Flush (reinitialise) a voice echo canceller context.
- * @ec: The echo canceller context.
- */
-void oslec_flush(struct oslec_state *ec);
-
-/**
- * oslec_adaption_mode - set the adaption mode of a voice echo canceller context.
- * @ec The echo canceller context.
- * @adaption_mode: The mode.
- */
-void oslec_adaption_mode(struct oslec_state *ec, int adaption_mode);
-
-void oslec_snapshot(struct oslec_state *ec);
-
-/**
- * oslec_update: Process a sample through a voice echo canceller.
- * @ec: The echo canceller context.
- * @tx: The transmitted audio sample.
- * @rx: The received audio sample.
- *
- * The return value is the clean (echo cancelled) received sample.
- */
-int16_t oslec_update(struct oslec_state *ec, int16_t tx, int16_t rx);
-
-/**
- * oslec_hpf_tx: Process to high pass filter the tx signal.
- * @ec: The echo canceller context.
- * @tx: The transmitted auio sample.
- *
- * The return value is the HP filtered transmit sample, send this to your D/A.
- */
-int16_t oslec_hpf_tx(struct oslec_state *ec, int16_t tx);
-
-#endif /* __OSLEC_H */