cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
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ad1843.c (15708B)


      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 *   AD1843 low level driver
      4 *
      5 *   Copyright 2003 Vivien Chappelier <vivien.chappelier@linux-mips.org>
      6 *   Copyright 2008 Thomas Bogendoerfer <tsbogend@alpha.franken.de>
      7 *
      8 *   inspired from vwsnd.c (SGI VW audio driver)
      9 *     Copyright 1999 Silicon Graphics, Inc.  All rights reserved.
     10 */
     11
     12#include <linux/init.h>
     13#include <linux/sched.h>
     14#include <linux/errno.h>
     15#include <sound/core.h>
     16#include <sound/pcm.h>
     17#include <sound/ad1843.h>
     18
     19/*
     20 * AD1843 bitfield definitions.  All are named as in the AD1843 data
     21 * sheet, with ad1843_ prepended and individual bit numbers removed.
     22 *
     23 * E.g., bits LSS0 through LSS2 become ad1843_LSS.
     24 *
     25 * Only the bitfields we need are defined.
     26 */
     27
     28struct ad1843_bitfield {
     29	char reg;
     30	char lo_bit;
     31	char nbits;
     32};
     33
     34static const struct ad1843_bitfield
     35	ad1843_PDNO   = {  0, 14,  1 },	/* Converter Power-Down Flag */
     36	ad1843_INIT   = {  0, 15,  1 },	/* Clock Initialization Flag */
     37	ad1843_RIG    = {  2,  0,  4 },	/* Right ADC Input Gain */
     38	ad1843_RMGE   = {  2,  4,  1 },	/* Right ADC Mic Gain Enable */
     39	ad1843_RSS    = {  2,  5,  3 },	/* Right ADC Source Select */
     40	ad1843_LIG    = {  2,  8,  4 },	/* Left ADC Input Gain */
     41	ad1843_LMGE   = {  2, 12,  1 },	/* Left ADC Mic Gain Enable */
     42	ad1843_LSS    = {  2, 13,  3 },	/* Left ADC Source Select */
     43	ad1843_RD2M   = {  3,  0,  5 },	/* Right DAC 2 Mix Gain/Atten */
     44	ad1843_RD2MM  = {  3,  7,  1 },	/* Right DAC 2 Mix Mute */
     45	ad1843_LD2M   = {  3,  8,  5 },	/* Left DAC 2 Mix Gain/Atten */
     46	ad1843_LD2MM  = {  3, 15,  1 },	/* Left DAC 2 Mix Mute */
     47	ad1843_RX1M   = {  4,  0,  5 },	/* Right Aux 1 Mix Gain/Atten */
     48	ad1843_RX1MM  = {  4,  7,  1 },	/* Right Aux 1 Mix Mute */
     49	ad1843_LX1M   = {  4,  8,  5 },	/* Left Aux 1 Mix Gain/Atten */
     50	ad1843_LX1MM  = {  4, 15,  1 },	/* Left Aux 1 Mix Mute */
     51	ad1843_RX2M   = {  5,  0,  5 },	/* Right Aux 2 Mix Gain/Atten */
     52	ad1843_RX2MM  = {  5,  7,  1 },	/* Right Aux 2 Mix Mute */
     53	ad1843_LX2M   = {  5,  8,  5 },	/* Left Aux 2 Mix Gain/Atten */
     54	ad1843_LX2MM  = {  5, 15,  1 },	/* Left Aux 2 Mix Mute */
     55	ad1843_RMCM   = {  7,  0,  5 },	/* Right Mic Mix Gain/Atten */
     56	ad1843_RMCMM  = {  7,  7,  1 },	/* Right Mic Mix Mute */
     57	ad1843_LMCM   = {  7,  8,  5 },	/* Left Mic Mix Gain/Atten */
     58	ad1843_LMCMM  = {  7, 15,  1 },	/* Left Mic Mix Mute */
     59	ad1843_HPOS   = {  8,  4,  1 },	/* Headphone Output Voltage Swing */
     60	ad1843_HPOM   = {  8,  5,  1 },	/* Headphone Output Mute */
     61	ad1843_MPOM   = {  8,  6,  1 },	/* Mono Output Mute */
     62	ad1843_RDA1G  = {  9,  0,  6 },	/* Right DAC1 Analog/Digital Gain */
     63	ad1843_RDA1GM = {  9,  7,  1 },	/* Right DAC1 Analog Mute */
     64	ad1843_LDA1G  = {  9,  8,  6 },	/* Left DAC1 Analog/Digital Gain */
     65	ad1843_LDA1GM = {  9, 15,  1 },	/* Left DAC1 Analog Mute */
     66	ad1843_RDA2G  = { 10,  0,  6 },	/* Right DAC2 Analog/Digital Gain */
     67	ad1843_RDA2GM = { 10,  7,  1 },	/* Right DAC2 Analog Mute */
     68	ad1843_LDA2G  = { 10,  8,  6 },	/* Left DAC2 Analog/Digital Gain */
     69	ad1843_LDA2GM = { 10, 15,  1 },	/* Left DAC2 Analog Mute */
     70	ad1843_RDA1AM = { 11,  7,  1 },	/* Right DAC1 Digital Mute */
     71	ad1843_LDA1AM = { 11, 15,  1 },	/* Left DAC1 Digital Mute */
     72	ad1843_RDA2AM = { 12,  7,  1 },	/* Right DAC2 Digital Mute */
     73	ad1843_LDA2AM = { 12, 15,  1 },	/* Left DAC2 Digital Mute */
     74	ad1843_ADLC   = { 15,  0,  2 },	/* ADC Left Sample Rate Source */
     75	ad1843_ADRC   = { 15,  2,  2 },	/* ADC Right Sample Rate Source */
     76	ad1843_DA1C   = { 15,  8,  2 },	/* DAC1 Sample Rate Source */
     77	ad1843_DA2C   = { 15, 10,  2 },	/* DAC2 Sample Rate Source */
     78	ad1843_C1C    = { 17,  0, 16 },	/* Clock 1 Sample Rate Select */
     79	ad1843_C2C    = { 20,  0, 16 },	/* Clock 2 Sample Rate Select */
     80	ad1843_C3C    = { 23,  0, 16 },	/* Clock 3 Sample Rate Select */
     81	ad1843_DAADL  = { 25,  4,  2 },	/* Digital ADC Left Source Select */
     82	ad1843_DAADR  = { 25,  6,  2 },	/* Digital ADC Right Source Select */
     83	ad1843_DAMIX  = { 25, 14,  1 },	/* DAC Digital Mix Enable */
     84	ad1843_DRSFLT = { 25, 15,  1 },	/* Digital Reampler Filter Mode */
     85	ad1843_ADLF   = { 26,  0,  2 }, /* ADC Left Channel Data Format */
     86	ad1843_ADRF   = { 26,  2,  2 }, /* ADC Right Channel Data Format */
     87	ad1843_ADTLK  = { 26,  4,  1 },	/* ADC Transmit Lock Mode Select */
     88	ad1843_SCF    = { 26,  7,  1 },	/* SCLK Frequency Select */
     89	ad1843_DA1F   = { 26,  8,  2 },	/* DAC1 Data Format Select */
     90	ad1843_DA2F   = { 26, 10,  2 },	/* DAC2 Data Format Select */
     91	ad1843_DA1SM  = { 26, 14,  1 },	/* DAC1 Stereo/Mono Mode Select */
     92	ad1843_DA2SM  = { 26, 15,  1 },	/* DAC2 Stereo/Mono Mode Select */
     93	ad1843_ADLEN  = { 27,  0,  1 },	/* ADC Left Channel Enable */
     94	ad1843_ADREN  = { 27,  1,  1 },	/* ADC Right Channel Enable */
     95	ad1843_AAMEN  = { 27,  4,  1 },	/* Analog to Analog Mix Enable */
     96	ad1843_ANAEN  = { 27,  7,  1 },	/* Analog Channel Enable */
     97	ad1843_DA1EN  = { 27,  8,  1 },	/* DAC1 Enable */
     98	ad1843_DA2EN  = { 27,  9,  1 },	/* DAC2 Enable */
     99	ad1843_DDMEN  = { 27, 12,  1 },	/* DAC2 to DAC1 Mix  Enable */
    100	ad1843_C1EN   = { 28, 11,  1 },	/* Clock Generator 1 Enable */
    101	ad1843_C2EN   = { 28, 12,  1 },	/* Clock Generator 2 Enable */
    102	ad1843_C3EN   = { 28, 13,  1 },	/* Clock Generator 3 Enable */
    103	ad1843_PDNI   = { 28, 15,  1 };	/* Converter Power Down */
    104
    105/*
    106 * The various registers of the AD1843 use three different formats for
    107 * specifying gain.  The ad1843_gain structure parameterizes the
    108 * formats.
    109 */
    110
    111struct ad1843_gain {
    112	int	negative;		/* nonzero if gain is negative. */
    113	const struct ad1843_bitfield *lfield;
    114	const struct ad1843_bitfield *rfield;
    115	const struct ad1843_bitfield *lmute;
    116	const struct ad1843_bitfield *rmute;
    117};
    118
    119static const struct ad1843_gain ad1843_gain_RECLEV = {
    120	.negative = 0,
    121	.lfield   = &ad1843_LIG,
    122	.rfield   = &ad1843_RIG
    123};
    124static const struct ad1843_gain ad1843_gain_LINE = {
    125	.negative = 1,
    126	.lfield   = &ad1843_LX1M,
    127	.rfield   = &ad1843_RX1M,
    128	.lmute    = &ad1843_LX1MM,
    129	.rmute    = &ad1843_RX1MM
    130};
    131static const struct ad1843_gain ad1843_gain_LINE_2 = {
    132	.negative = 1,
    133	.lfield   = &ad1843_LDA2G,
    134	.rfield   = &ad1843_RDA2G,
    135	.lmute    = &ad1843_LDA2GM,
    136	.rmute    = &ad1843_RDA2GM
    137};
    138static const struct ad1843_gain ad1843_gain_MIC = {
    139	.negative = 1,
    140	.lfield   = &ad1843_LMCM,
    141	.rfield   = &ad1843_RMCM,
    142	.lmute    = &ad1843_LMCMM,
    143	.rmute    = &ad1843_RMCMM
    144};
    145static const struct ad1843_gain ad1843_gain_PCM_0 = {
    146	.negative = 1,
    147	.lfield   = &ad1843_LDA1G,
    148	.rfield   = &ad1843_RDA1G,
    149	.lmute    = &ad1843_LDA1GM,
    150	.rmute    = &ad1843_RDA1GM
    151};
    152static const struct ad1843_gain ad1843_gain_PCM_1 = {
    153	.negative = 1,
    154	.lfield   = &ad1843_LD2M,
    155	.rfield   = &ad1843_RD2M,
    156	.lmute    = &ad1843_LD2MM,
    157	.rmute    = &ad1843_RD2MM
    158};
    159
    160static const struct ad1843_gain *ad1843_gain[AD1843_GAIN_SIZE] =
    161{
    162	&ad1843_gain_RECLEV,
    163	&ad1843_gain_LINE,
    164	&ad1843_gain_LINE_2,
    165	&ad1843_gain_MIC,
    166	&ad1843_gain_PCM_0,
    167	&ad1843_gain_PCM_1,
    168};
    169
    170/* read the current value of an AD1843 bitfield. */
    171
    172static int ad1843_read_bits(struct snd_ad1843 *ad1843,
    173			    const struct ad1843_bitfield *field)
    174{
    175	int w;
    176
    177	w = ad1843->read(ad1843->chip, field->reg);
    178	return w >> field->lo_bit & ((1 << field->nbits) - 1);
    179}
    180
    181/*
    182 * write a new value to an AD1843 bitfield and return the old value.
    183 */
    184
    185static int ad1843_write_bits(struct snd_ad1843 *ad1843,
    186			     const struct ad1843_bitfield *field,
    187			     int newval)
    188{
    189	int w, mask, oldval, newbits;
    190
    191	w = ad1843->read(ad1843->chip, field->reg);
    192	mask = ((1 << field->nbits) - 1) << field->lo_bit;
    193	oldval = (w & mask) >> field->lo_bit;
    194	newbits = (newval << field->lo_bit) & mask;
    195	w = (w & ~mask) | newbits;
    196	ad1843->write(ad1843->chip, field->reg, w);
    197
    198	return oldval;
    199}
    200
    201/*
    202 * ad1843_read_multi reads multiple bitfields from the same AD1843
    203 * register.  It uses a single read cycle to do it.  (Reading the
    204 * ad1843 requires 256 bit times at 12.288 MHz, or nearly 20
    205 * microseconds.)
    206 *
    207 * Called like this.
    208 *
    209 *  ad1843_read_multi(ad1843, nfields,
    210 *		      &ad1843_FIELD1, &val1,
    211 *		      &ad1843_FIELD2, &val2, ...);
    212 */
    213
    214static void ad1843_read_multi(struct snd_ad1843 *ad1843, int argcount, ...)
    215{
    216	va_list ap;
    217	const struct ad1843_bitfield *fp;
    218	int w = 0, mask, *value, reg = -1;
    219
    220	va_start(ap, argcount);
    221	while (--argcount >= 0) {
    222		fp = va_arg(ap, const struct ad1843_bitfield *);
    223		value = va_arg(ap, int *);
    224		if (reg == -1) {
    225			reg = fp->reg;
    226			w = ad1843->read(ad1843->chip, reg);
    227		}
    228
    229		mask = (1 << fp->nbits) - 1;
    230		*value = w >> fp->lo_bit & mask;
    231	}
    232	va_end(ap);
    233}
    234
    235/*
    236 * ad1843_write_multi stores multiple bitfields into the same AD1843
    237 * register.  It uses one read and one write cycle to do it.
    238 *
    239 * Called like this.
    240 *
    241 *  ad1843_write_multi(ad1843, nfields,
    242 *		       &ad1843_FIELD1, val1,
    243 *		       &ad1843_FIELF2, val2, ...);
    244 */
    245
    246static void ad1843_write_multi(struct snd_ad1843 *ad1843, int argcount, ...)
    247{
    248	va_list ap;
    249	int reg;
    250	const struct ad1843_bitfield *fp;
    251	int value;
    252	int w, m, mask, bits;
    253
    254	mask = 0;
    255	bits = 0;
    256	reg = -1;
    257
    258	va_start(ap, argcount);
    259	while (--argcount >= 0) {
    260		fp = va_arg(ap, const struct ad1843_bitfield *);
    261		value = va_arg(ap, int);
    262		if (reg == -1)
    263			reg = fp->reg;
    264		else
    265			WARN_ON(reg != fp->reg);
    266		m = ((1 << fp->nbits) - 1) << fp->lo_bit;
    267		mask |= m;
    268		bits |= (value << fp->lo_bit) & m;
    269	}
    270	va_end(ap);
    271
    272	if (~mask & 0xFFFF)
    273		w = ad1843->read(ad1843->chip, reg);
    274	else
    275		w = 0;
    276	w = (w & ~mask) | bits;
    277	ad1843->write(ad1843->chip, reg, w);
    278}
    279
    280int ad1843_get_gain_max(struct snd_ad1843 *ad1843, int id)
    281{
    282	const struct ad1843_gain *gp = ad1843_gain[id];
    283	int ret;
    284
    285	ret = (1 << gp->lfield->nbits);
    286	if (!gp->lmute)
    287		ret -= 1;
    288	return ret;
    289}
    290
    291/*
    292 * ad1843_get_gain reads the specified register and extracts the gain value
    293 * using the supplied gain type.
    294 */
    295
    296int ad1843_get_gain(struct snd_ad1843 *ad1843, int id)
    297{
    298	int lg, rg, lm, rm;
    299	const struct ad1843_gain *gp = ad1843_gain[id];
    300	unsigned short mask = (1 << gp->lfield->nbits) - 1;
    301
    302	ad1843_read_multi(ad1843, 2, gp->lfield, &lg, gp->rfield, &rg);
    303	if (gp->negative) {
    304		lg = mask - lg;
    305		rg = mask - rg;
    306	}
    307	if (gp->lmute) {
    308		ad1843_read_multi(ad1843, 2, gp->lmute, &lm, gp->rmute, &rm);
    309		if (lm)
    310			lg = 0;
    311		if (rm)
    312			rg = 0;
    313	}
    314	return lg << 0 | rg << 8;
    315}
    316
    317/*
    318 * Set an audio channel's gain.
    319 *
    320 * Returns the new gain, which may be lower than the old gain.
    321 */
    322
    323int ad1843_set_gain(struct snd_ad1843 *ad1843, int id, int newval)
    324{
    325	const struct ad1843_gain *gp = ad1843_gain[id];
    326	unsigned short mask = (1 << gp->lfield->nbits) - 1;
    327
    328	int lg = (newval >> 0) & mask;
    329	int rg = (newval >> 8) & mask;
    330	int lm = (lg == 0) ? 1 : 0;
    331	int rm = (rg == 0) ? 1 : 0;
    332
    333	if (gp->negative) {
    334		lg = mask - lg;
    335		rg = mask - rg;
    336	}
    337	if (gp->lmute)
    338		ad1843_write_multi(ad1843, 2, gp->lmute, lm, gp->rmute, rm);
    339	ad1843_write_multi(ad1843, 2, gp->lfield, lg, gp->rfield, rg);
    340	return ad1843_get_gain(ad1843, id);
    341}
    342
    343/* Returns the current recording source */
    344
    345int ad1843_get_recsrc(struct snd_ad1843 *ad1843)
    346{
    347	int val = ad1843_read_bits(ad1843, &ad1843_LSS);
    348
    349	if (val < 0 || val > 2) {
    350		val = 2;
    351		ad1843_write_multi(ad1843, 2,
    352				   &ad1843_LSS, val, &ad1843_RSS, val);
    353	}
    354	return val;
    355}
    356
    357/*
    358 * Set recording source.
    359 *
    360 * Returns newsrc on success, -errno on failure.
    361 */
    362
    363int ad1843_set_recsrc(struct snd_ad1843 *ad1843, int newsrc)
    364{
    365	if (newsrc < 0 || newsrc > 2)
    366		return -EINVAL;
    367
    368	ad1843_write_multi(ad1843, 2, &ad1843_LSS, newsrc, &ad1843_RSS, newsrc);
    369	return newsrc;
    370}
    371
    372/* Setup ad1843 for D/A conversion. */
    373
    374void ad1843_setup_dac(struct snd_ad1843 *ad1843,
    375		      unsigned int id,
    376		      unsigned int framerate,
    377		      snd_pcm_format_t fmt,
    378		      unsigned int channels)
    379{
    380	int ad_fmt = 0, ad_mode = 0;
    381
    382	switch (fmt) {
    383	case SNDRV_PCM_FORMAT_S8:
    384		ad_fmt = 0;
    385		break;
    386	case SNDRV_PCM_FORMAT_U8:
    387		ad_fmt = 0;
    388		break;
    389	case SNDRV_PCM_FORMAT_S16_LE:
    390		ad_fmt = 1;
    391		break;
    392	case SNDRV_PCM_FORMAT_MU_LAW:
    393		ad_fmt = 2;
    394		break;
    395	case SNDRV_PCM_FORMAT_A_LAW:
    396		ad_fmt = 3;
    397		break;
    398	default:
    399		break;
    400	}
    401
    402	switch (channels) {
    403	case 2:
    404		ad_mode = 0;
    405		break;
    406	case 1:
    407		ad_mode = 1;
    408		break;
    409	default:
    410		break;
    411	}
    412
    413	if (id) {
    414		ad1843_write_bits(ad1843, &ad1843_C2C, framerate);
    415		ad1843_write_multi(ad1843, 2,
    416				   &ad1843_DA2SM, ad_mode,
    417				   &ad1843_DA2F, ad_fmt);
    418	} else {
    419		ad1843_write_bits(ad1843, &ad1843_C1C, framerate);
    420		ad1843_write_multi(ad1843, 2,
    421				   &ad1843_DA1SM, ad_mode,
    422				   &ad1843_DA1F, ad_fmt);
    423	}
    424}
    425
    426void ad1843_shutdown_dac(struct snd_ad1843 *ad1843, unsigned int id)
    427{
    428	if (id)
    429		ad1843_write_bits(ad1843, &ad1843_DA2F, 1);
    430	else
    431		ad1843_write_bits(ad1843, &ad1843_DA1F, 1);
    432}
    433
    434void ad1843_setup_adc(struct snd_ad1843 *ad1843,
    435		      unsigned int framerate,
    436		      snd_pcm_format_t fmt,
    437		      unsigned int channels)
    438{
    439	int da_fmt = 0;
    440
    441	switch (fmt) {
    442	case SNDRV_PCM_FORMAT_S8:	da_fmt = 0; break;
    443	case SNDRV_PCM_FORMAT_U8:	da_fmt = 0; break;
    444	case SNDRV_PCM_FORMAT_S16_LE:	da_fmt = 1; break;
    445	case SNDRV_PCM_FORMAT_MU_LAW:	da_fmt = 2; break;
    446	case SNDRV_PCM_FORMAT_A_LAW:	da_fmt = 3; break;
    447	default:		break;
    448	}
    449
    450	ad1843_write_bits(ad1843, &ad1843_C3C, framerate);
    451	ad1843_write_multi(ad1843, 2,
    452			   &ad1843_ADLF, da_fmt, &ad1843_ADRF, da_fmt);
    453}
    454
    455void ad1843_shutdown_adc(struct snd_ad1843 *ad1843)
    456{
    457	/* nothing to do */
    458}
    459
    460/*
    461 * Fully initialize the ad1843.  As described in the AD1843 data
    462 * sheet, section "START-UP SEQUENCE".  The numbered comments are
    463 * subsection headings from the data sheet.  See the data sheet, pages
    464 * 52-54, for more info.
    465 *
    466 * return 0 on success, -errno on failure.  */
    467
    468int ad1843_init(struct snd_ad1843 *ad1843)
    469{
    470	unsigned long later;
    471
    472	if (ad1843_read_bits(ad1843, &ad1843_INIT) != 0) {
    473		printk(KERN_ERR "ad1843: AD1843 won't initialize\n");
    474		return -EIO;
    475	}
    476
    477	ad1843_write_bits(ad1843, &ad1843_SCF, 1);
    478
    479	/* 4. Put the conversion resources into standby. */
    480	ad1843_write_bits(ad1843, &ad1843_PDNI, 0);
    481	later = jiffies + msecs_to_jiffies(500);
    482
    483	while (ad1843_read_bits(ad1843, &ad1843_PDNO)) {
    484		if (time_after(jiffies, later)) {
    485			printk(KERN_ERR
    486			       "ad1843: AD1843 won't power up\n");
    487			return -EIO;
    488		}
    489		schedule_timeout_interruptible(5);
    490	}
    491
    492	/* 5. Power up the clock generators and enable clock output pins. */
    493	ad1843_write_multi(ad1843, 3,
    494			   &ad1843_C1EN, 1,
    495			   &ad1843_C2EN, 1,
    496			   &ad1843_C3EN, 1);
    497
    498	/* 6. Configure conversion resources while they are in standby. */
    499
    500	/* DAC1/2 use clock 1/2 as source, ADC uses clock 3.  Always. */
    501	ad1843_write_multi(ad1843, 4,
    502			   &ad1843_DA1C, 1,
    503			   &ad1843_DA2C, 2,
    504			   &ad1843_ADLC, 3,
    505			   &ad1843_ADRC, 3);
    506
    507	/* 7. Enable conversion resources. */
    508	ad1843_write_bits(ad1843, &ad1843_ADTLK, 1);
    509	ad1843_write_multi(ad1843, 7,
    510			   &ad1843_ANAEN, 1,
    511			   &ad1843_AAMEN, 1,
    512			   &ad1843_DA1EN, 1,
    513			   &ad1843_DA2EN, 1,
    514			   &ad1843_DDMEN, 1,
    515			   &ad1843_ADLEN, 1,
    516			   &ad1843_ADREN, 1);
    517
    518	/* 8. Configure conversion resources while they are enabled. */
    519
    520	/* set gain to 0 for all channels */
    521	ad1843_set_gain(ad1843, AD1843_GAIN_RECLEV, 0);
    522	ad1843_set_gain(ad1843, AD1843_GAIN_LINE, 0);
    523	ad1843_set_gain(ad1843, AD1843_GAIN_LINE_2, 0);
    524	ad1843_set_gain(ad1843, AD1843_GAIN_MIC, 0);
    525	ad1843_set_gain(ad1843, AD1843_GAIN_PCM_0, 0);
    526	ad1843_set_gain(ad1843, AD1843_GAIN_PCM_1, 0);
    527
    528	/* Unmute all channels. */
    529	/* DAC1 */
    530	ad1843_write_multi(ad1843, 2, &ad1843_LDA1GM, 0, &ad1843_RDA1GM, 0);
    531	/* DAC2 */
    532	ad1843_write_multi(ad1843, 2, &ad1843_LDA2GM, 0, &ad1843_RDA2GM, 0);
    533
    534	/* Set default recording source to Line In and set
    535	 * mic gain to +20 dB.
    536	 */
    537	ad1843_set_recsrc(ad1843, 2);
    538	ad1843_write_multi(ad1843, 2, &ad1843_LMGE, 1, &ad1843_RMGE, 1);
    539
    540	/* Set Speaker Out level to +/- 4V and unmute it. */
    541	ad1843_write_multi(ad1843, 3,
    542			   &ad1843_HPOS, 1,
    543			   &ad1843_HPOM, 0,
    544			   &ad1843_MPOM, 0);
    545
    546	return 0;
    547}