xref: /openbmc/linux/sound/mips/ad1843.c (revision 8dde5715)
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 
28 struct ad1843_bitfield {
29 	char reg;
30 	char lo_bit;
31 	char nbits;
32 };
33 
34 static 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 
111 struct 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 
119 static const struct ad1843_gain ad1843_gain_RECLEV = {
120 	.negative = 0,
121 	.lfield   = &ad1843_LIG,
122 	.rfield   = &ad1843_RIG
123 };
124 static 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 };
131 static 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 };
138 static 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 };
145 static 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 };
152 static 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 
160 static 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 
172 static 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 
185 static 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 
214 static 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 
246 static 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 
280 int 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 
296 int 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 
323 int 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 
345 int 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 
363 int 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 
374 void 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 
426 void 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 
434 void 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 
455 void 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 
468 int 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 }
548