1 /*
2     Auvitek AU8522 QAM/8VSB demodulator driver
3 
4     Copyright (C) 2008 Steven Toth <stoth@linuxtv.org>
5 
6     This program is free software; you can redistribute it and/or modify
7     it under the terms of the GNU General Public License as published by
8     the Free Software Foundation; either version 2 of the License, or
9     (at your option) any later version.
10 
11     This program is distributed in the hope that it will be useful,
12     but WITHOUT ANY WARRANTY; without even the implied warranty of
13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14     GNU General Public License for more details.
15 
16     You should have received a copy of the GNU General Public License
17     along with this program; if not, write to the Free Software
18     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19 
20 */
21 
22 #include <linux/kernel.h>
23 #include <linux/init.h>
24 #include <linux/module.h>
25 #include <linux/string.h>
26 #include <linux/delay.h>
27 #include "dvb_frontend.h"
28 #include "au8522.h"
29 #include "au8522_priv.h"
30 
31 static int debug;
32 
33 #define dprintk(arg...)\
34 	do { if (debug)\
35 		printk(arg);\
36 	} while (0)
37 
38 struct mse2snr_tab {
39 	u16 val;
40 	u16 data;
41 };
42 
43 /* VSB SNR lookup table */
44 static struct mse2snr_tab vsb_mse2snr_tab[] = {
45 	{   0, 270 },
46 	{   2, 250 },
47 	{   3, 240 },
48 	{   5, 230 },
49 	{   7, 220 },
50 	{   9, 210 },
51 	{  12, 200 },
52 	{  13, 195 },
53 	{  15, 190 },
54 	{  17, 185 },
55 	{  19, 180 },
56 	{  21, 175 },
57 	{  24, 170 },
58 	{  27, 165 },
59 	{  31, 160 },
60 	{  32, 158 },
61 	{  33, 156 },
62 	{  36, 152 },
63 	{  37, 150 },
64 	{  39, 148 },
65 	{  40, 146 },
66 	{  41, 144 },
67 	{  43, 142 },
68 	{  44, 140 },
69 	{  48, 135 },
70 	{  50, 130 },
71 	{  43, 142 },
72 	{  53, 125 },
73 	{  56, 120 },
74 	{ 256, 115 },
75 };
76 
77 /* QAM64 SNR lookup table */
78 static struct mse2snr_tab qam64_mse2snr_tab[] = {
79 	{  15,   0 },
80 	{  16, 290 },
81 	{  17, 288 },
82 	{  18, 286 },
83 	{  19, 284 },
84 	{  20, 282 },
85 	{  21, 281 },
86 	{  22, 279 },
87 	{  23, 277 },
88 	{  24, 275 },
89 	{  25, 273 },
90 	{  26, 271 },
91 	{  27, 269 },
92 	{  28, 268 },
93 	{  29, 266 },
94 	{  30, 264 },
95 	{  31, 262 },
96 	{  32, 260 },
97 	{  33, 259 },
98 	{  34, 258 },
99 	{  35, 256 },
100 	{  36, 255 },
101 	{  37, 254 },
102 	{  38, 252 },
103 	{  39, 251 },
104 	{  40, 250 },
105 	{  41, 249 },
106 	{  42, 248 },
107 	{  43, 246 },
108 	{  44, 245 },
109 	{  45, 244 },
110 	{  46, 242 },
111 	{  47, 241 },
112 	{  48, 240 },
113 	{  50, 239 },
114 	{  51, 238 },
115 	{  53, 237 },
116 	{  54, 236 },
117 	{  56, 235 },
118 	{  57, 234 },
119 	{  59, 233 },
120 	{  60, 232 },
121 	{  62, 231 },
122 	{  63, 230 },
123 	{  65, 229 },
124 	{  67, 228 },
125 	{  68, 227 },
126 	{  70, 226 },
127 	{  71, 225 },
128 	{  73, 224 },
129 	{  74, 223 },
130 	{  76, 222 },
131 	{  78, 221 },
132 	{  80, 220 },
133 	{  82, 219 },
134 	{  85, 218 },
135 	{  88, 217 },
136 	{  90, 216 },
137 	{  92, 215 },
138 	{  93, 214 },
139 	{  94, 212 },
140 	{  95, 211 },
141 	{  97, 210 },
142 	{  99, 209 },
143 	{ 101, 208 },
144 	{ 102, 207 },
145 	{ 104, 206 },
146 	{ 107, 205 },
147 	{ 111, 204 },
148 	{ 114, 203 },
149 	{ 118, 202 },
150 	{ 122, 201 },
151 	{ 125, 200 },
152 	{ 128, 199 },
153 	{ 130, 198 },
154 	{ 132, 197 },
155 	{ 256, 190 },
156 };
157 
158 /* QAM256 SNR lookup table */
159 static struct mse2snr_tab qam256_mse2snr_tab[] = {
160 	{  15,   0 },
161 	{  16, 400 },
162 	{  17, 398 },
163 	{  18, 396 },
164 	{  19, 394 },
165 	{  20, 392 },
166 	{  21, 390 },
167 	{  22, 388 },
168 	{  23, 386 },
169 	{  24, 384 },
170 	{  25, 382 },
171 	{  26, 380 },
172 	{  27, 379 },
173 	{  28, 378 },
174 	{  29, 377 },
175 	{  30, 376 },
176 	{  31, 375 },
177 	{  32, 374 },
178 	{  33, 373 },
179 	{  34, 372 },
180 	{  35, 371 },
181 	{  36, 370 },
182 	{  37, 362 },
183 	{  38, 354 },
184 	{  39, 346 },
185 	{  40, 338 },
186 	{  41, 330 },
187 	{  42, 328 },
188 	{  43, 326 },
189 	{  44, 324 },
190 	{  45, 322 },
191 	{  46, 320 },
192 	{  47, 319 },
193 	{  48, 318 },
194 	{  49, 317 },
195 	{  50, 316 },
196 	{  51, 315 },
197 	{  52, 314 },
198 	{  53, 313 },
199 	{  54, 312 },
200 	{  55, 311 },
201 	{  56, 310 },
202 	{  57, 308 },
203 	{  58, 306 },
204 	{  59, 304 },
205 	{  60, 302 },
206 	{  61, 300 },
207 	{  62, 298 },
208 	{  65, 295 },
209 	{  68, 294 },
210 	{  70, 293 },
211 	{  73, 292 },
212 	{  76, 291 },
213 	{  78, 290 },
214 	{  79, 289 },
215 	{  81, 288 },
216 	{  82, 287 },
217 	{  83, 286 },
218 	{  84, 285 },
219 	{  85, 284 },
220 	{  86, 283 },
221 	{  88, 282 },
222 	{  89, 281 },
223 	{ 256, 280 },
224 };
225 
226 static int au8522_mse2snr_lookup(struct mse2snr_tab *tab, int sz, int mse,
227 				 u16 *snr)
228 {
229 	int i, ret = -EINVAL;
230 	dprintk("%s()\n", __func__);
231 
232 	for (i = 0; i < sz; i++) {
233 		if (mse < tab[i].val) {
234 			*snr = tab[i].data;
235 			ret = 0;
236 			break;
237 		}
238 	}
239 	dprintk("%s() snr=%d\n", __func__, *snr);
240 	return ret;
241 }
242 
243 static int au8522_set_if(struct dvb_frontend *fe, enum au8522_if_freq if_freq)
244 {
245 	struct au8522_state *state = fe->demodulator_priv;
246 	u8 r0b5, r0b6, r0b7;
247 	char *ifmhz;
248 
249 	switch (if_freq) {
250 	case AU8522_IF_3_25MHZ:
251 		ifmhz = "3.25";
252 		r0b5 = 0x00;
253 		r0b6 = 0x3d;
254 		r0b7 = 0xa0;
255 		break;
256 	case AU8522_IF_4MHZ:
257 		ifmhz = "4.00";
258 		r0b5 = 0x00;
259 		r0b6 = 0x4b;
260 		r0b7 = 0xd9;
261 		break;
262 	case AU8522_IF_6MHZ:
263 		ifmhz = "6.00";
264 		r0b5 = 0xfb;
265 		r0b6 = 0x8e;
266 		r0b7 = 0x39;
267 		break;
268 	default:
269 		dprintk("%s() IF Frequency not supported\n", __func__);
270 		return -EINVAL;
271 	}
272 	dprintk("%s() %s MHz\n", __func__, ifmhz);
273 	au8522_writereg(state, 0x80b5, r0b5);
274 	au8522_writereg(state, 0x80b6, r0b6);
275 	au8522_writereg(state, 0x80b7, r0b7);
276 
277 	return 0;
278 }
279 
280 /* VSB Modulation table */
281 static struct {
282 	u16 reg;
283 	u16 data;
284 } VSB_mod_tab[] = {
285 	{ 0x8090, 0x84 },
286 	{ 0x4092, 0x11 },
287 	{ 0x2005, 0x00 },
288 	{ 0x8091, 0x80 },
289 	{ 0x80a3, 0x0c },
290 	{ 0x80a4, 0xe8 },
291 	{ 0x8081, 0xc4 },
292 	{ 0x80a5, 0x40 },
293 	{ 0x80a7, 0x40 },
294 	{ 0x80a6, 0x67 },
295 	{ 0x8262, 0x20 },
296 	{ 0x821c, 0x30 },
297 	{ 0x80d8, 0x1a },
298 	{ 0x8227, 0xa0 },
299 	{ 0x8121, 0xff },
300 	{ 0x80a8, 0xf0 },
301 	{ 0x80a9, 0x05 },
302 	{ 0x80aa, 0x77 },
303 	{ 0x80ab, 0xf0 },
304 	{ 0x80ac, 0x05 },
305 	{ 0x80ad, 0x77 },
306 	{ 0x80ae, 0x41 },
307 	{ 0x80af, 0x66 },
308 	{ 0x821b, 0xcc },
309 	{ 0x821d, 0x80 },
310 	{ 0x80a4, 0xe8 },
311 	{ 0x8231, 0x13 },
312 };
313 
314 /* QAM64 Modulation table */
315 static struct {
316 	u16 reg;
317 	u16 data;
318 } QAM64_mod_tab[] = {
319 	{ 0x00a3, 0x09 },
320 	{ 0x00a4, 0x00 },
321 	{ 0x0081, 0xc4 },
322 	{ 0x00a5, 0x40 },
323 	{ 0x00aa, 0x77 },
324 	{ 0x00ad, 0x77 },
325 	{ 0x00a6, 0x67 },
326 	{ 0x0262, 0x20 },
327 	{ 0x021c, 0x30 },
328 	{ 0x00b8, 0x3e },
329 	{ 0x00b9, 0xf0 },
330 	{ 0x00ba, 0x01 },
331 	{ 0x00bb, 0x18 },
332 	{ 0x00bc, 0x50 },
333 	{ 0x00bd, 0x00 },
334 	{ 0x00be, 0xea },
335 	{ 0x00bf, 0xef },
336 	{ 0x00c0, 0xfc },
337 	{ 0x00c1, 0xbd },
338 	{ 0x00c2, 0x1f },
339 	{ 0x00c3, 0xfc },
340 	{ 0x00c4, 0xdd },
341 	{ 0x00c5, 0xaf },
342 	{ 0x00c6, 0x00 },
343 	{ 0x00c7, 0x38 },
344 	{ 0x00c8, 0x30 },
345 	{ 0x00c9, 0x05 },
346 	{ 0x00ca, 0x4a },
347 	{ 0x00cb, 0xd0 },
348 	{ 0x00cc, 0x01 },
349 	{ 0x00cd, 0xd9 },
350 	{ 0x00ce, 0x6f },
351 	{ 0x00cf, 0xf9 },
352 	{ 0x00d0, 0x70 },
353 	{ 0x00d1, 0xdf },
354 	{ 0x00d2, 0xf7 },
355 	{ 0x00d3, 0xc2 },
356 	{ 0x00d4, 0xdf },
357 	{ 0x00d5, 0x02 },
358 	{ 0x00d6, 0x9a },
359 	{ 0x00d7, 0xd0 },
360 	{ 0x0250, 0x0d },
361 	{ 0x0251, 0xcd },
362 	{ 0x0252, 0xe0 },
363 	{ 0x0253, 0x05 },
364 	{ 0x0254, 0xa7 },
365 	{ 0x0255, 0xff },
366 	{ 0x0256, 0xed },
367 	{ 0x0257, 0x5b },
368 	{ 0x0258, 0xae },
369 	{ 0x0259, 0xe6 },
370 	{ 0x025a, 0x3d },
371 	{ 0x025b, 0x0f },
372 	{ 0x025c, 0x0d },
373 	{ 0x025d, 0xea },
374 	{ 0x025e, 0xf2 },
375 	{ 0x025f, 0x51 },
376 	{ 0x0260, 0xf5 },
377 	{ 0x0261, 0x06 },
378 	{ 0x021a, 0x00 },
379 	{ 0x0546, 0x40 },
380 	{ 0x0210, 0xc7 },
381 	{ 0x0211, 0xaa },
382 	{ 0x0212, 0xab },
383 	{ 0x0213, 0x02 },
384 	{ 0x0502, 0x00 },
385 	{ 0x0121, 0x04 },
386 	{ 0x0122, 0x04 },
387 	{ 0x052e, 0x10 },
388 	{ 0x00a4, 0xca },
389 	{ 0x00a7, 0x40 },
390 	{ 0x0526, 0x01 },
391 };
392 
393 /* QAM256 Modulation table */
394 static struct {
395 	u16 reg;
396 	u16 data;
397 } QAM256_mod_tab[] = {
398 	{ 0x80a3, 0x09 },
399 	{ 0x80a4, 0x00 },
400 	{ 0x8081, 0xc4 },
401 	{ 0x80a5, 0x40 },
402 	{ 0x80aa, 0x77 },
403 	{ 0x80ad, 0x77 },
404 	{ 0x80a6, 0x67 },
405 	{ 0x8262, 0x20 },
406 	{ 0x821c, 0x30 },
407 	{ 0x80b8, 0x3e },
408 	{ 0x80b9, 0xf0 },
409 	{ 0x80ba, 0x01 },
410 	{ 0x80bb, 0x18 },
411 	{ 0x80bc, 0x50 },
412 	{ 0x80bd, 0x00 },
413 	{ 0x80be, 0xea },
414 	{ 0x80bf, 0xef },
415 	{ 0x80c0, 0xfc },
416 	{ 0x80c1, 0xbd },
417 	{ 0x80c2, 0x1f },
418 	{ 0x80c3, 0xfc },
419 	{ 0x80c4, 0xdd },
420 	{ 0x80c5, 0xaf },
421 	{ 0x80c6, 0x00 },
422 	{ 0x80c7, 0x38 },
423 	{ 0x80c8, 0x30 },
424 	{ 0x80c9, 0x05 },
425 	{ 0x80ca, 0x4a },
426 	{ 0x80cb, 0xd0 },
427 	{ 0x80cc, 0x01 },
428 	{ 0x80cd, 0xd9 },
429 	{ 0x80ce, 0x6f },
430 	{ 0x80cf, 0xf9 },
431 	{ 0x80d0, 0x70 },
432 	{ 0x80d1, 0xdf },
433 	{ 0x80d2, 0xf7 },
434 	{ 0x80d3, 0xc2 },
435 	{ 0x80d4, 0xdf },
436 	{ 0x80d5, 0x02 },
437 	{ 0x80d6, 0x9a },
438 	{ 0x80d7, 0xd0 },
439 	{ 0x8250, 0x0d },
440 	{ 0x8251, 0xcd },
441 	{ 0x8252, 0xe0 },
442 	{ 0x8253, 0x05 },
443 	{ 0x8254, 0xa7 },
444 	{ 0x8255, 0xff },
445 	{ 0x8256, 0xed },
446 	{ 0x8257, 0x5b },
447 	{ 0x8258, 0xae },
448 	{ 0x8259, 0xe6 },
449 	{ 0x825a, 0x3d },
450 	{ 0x825b, 0x0f },
451 	{ 0x825c, 0x0d },
452 	{ 0x825d, 0xea },
453 	{ 0x825e, 0xf2 },
454 	{ 0x825f, 0x51 },
455 	{ 0x8260, 0xf5 },
456 	{ 0x8261, 0x06 },
457 	{ 0x821a, 0x00 },
458 	{ 0x8546, 0x40 },
459 	{ 0x8210, 0x26 },
460 	{ 0x8211, 0xf6 },
461 	{ 0x8212, 0x84 },
462 	{ 0x8213, 0x02 },
463 	{ 0x8502, 0x01 },
464 	{ 0x8121, 0x04 },
465 	{ 0x8122, 0x04 },
466 	{ 0x852e, 0x10 },
467 	{ 0x80a4, 0xca },
468 	{ 0x80a7, 0x40 },
469 	{ 0x8526, 0x01 },
470 };
471 
472 static int au8522_enable_modulation(struct dvb_frontend *fe,
473 				    fe_modulation_t m)
474 {
475 	struct au8522_state *state = fe->demodulator_priv;
476 	int i;
477 
478 	dprintk("%s(0x%08x)\n", __func__, m);
479 
480 	switch (m) {
481 	case VSB_8:
482 		dprintk("%s() VSB_8\n", __func__);
483 		for (i = 0; i < ARRAY_SIZE(VSB_mod_tab); i++)
484 			au8522_writereg(state,
485 				VSB_mod_tab[i].reg,
486 				VSB_mod_tab[i].data);
487 		au8522_set_if(fe, state->config->vsb_if);
488 		break;
489 	case QAM_64:
490 		dprintk("%s() QAM 64\n", __func__);
491 		for (i = 0; i < ARRAY_SIZE(QAM64_mod_tab); i++)
492 			au8522_writereg(state,
493 				QAM64_mod_tab[i].reg,
494 				QAM64_mod_tab[i].data);
495 		au8522_set_if(fe, state->config->qam_if);
496 		break;
497 	case QAM_256:
498 		dprintk("%s() QAM 256\n", __func__);
499 		for (i = 0; i < ARRAY_SIZE(QAM256_mod_tab); i++)
500 			au8522_writereg(state,
501 				QAM256_mod_tab[i].reg,
502 				QAM256_mod_tab[i].data);
503 		au8522_set_if(fe, state->config->qam_if);
504 		break;
505 	default:
506 		dprintk("%s() Invalid modulation\n", __func__);
507 		return -EINVAL;
508 	}
509 
510 	state->current_modulation = m;
511 
512 	return 0;
513 }
514 
515 /* Talk to the demod, set the FEC, GUARD, QAM settings etc */
516 static int au8522_set_frontend(struct dvb_frontend *fe)
517 {
518 	struct dtv_frontend_properties *c = &fe->dtv_property_cache;
519 	struct au8522_state *state = fe->demodulator_priv;
520 	int ret = -EINVAL;
521 
522 	dprintk("%s(frequency=%d)\n", __func__, c->frequency);
523 
524 	if ((state->current_frequency == c->frequency) &&
525 	    (state->current_modulation == c->modulation))
526 		return 0;
527 
528 	if (fe->ops.tuner_ops.set_params) {
529 		if (fe->ops.i2c_gate_ctrl)
530 			fe->ops.i2c_gate_ctrl(fe, 1);
531 		ret = fe->ops.tuner_ops.set_params(fe);
532 		if (fe->ops.i2c_gate_ctrl)
533 			fe->ops.i2c_gate_ctrl(fe, 0);
534 	}
535 
536 	if (ret < 0)
537 		return ret;
538 
539 	/* Allow the tuner to settle */
540 	msleep(100);
541 
542 	au8522_enable_modulation(fe, c->modulation);
543 
544 	state->current_frequency = c->frequency;
545 
546 	return 0;
547 }
548 
549 static int au8522_read_status(struct dvb_frontend *fe, fe_status_t *status)
550 {
551 	struct au8522_state *state = fe->demodulator_priv;
552 	u8 reg;
553 	u32 tuner_status = 0;
554 
555 	*status = 0;
556 
557 	if (state->current_modulation == VSB_8) {
558 		dprintk("%s() Checking VSB_8\n", __func__);
559 		reg = au8522_readreg(state, 0x4088);
560 		if ((reg & 0x03) == 0x03)
561 			*status |= FE_HAS_LOCK | FE_HAS_SYNC | FE_HAS_VITERBI;
562 	} else {
563 		dprintk("%s() Checking QAM\n", __func__);
564 		reg = au8522_readreg(state, 0x4541);
565 		if (reg & 0x80)
566 			*status |= FE_HAS_VITERBI;
567 		if (reg & 0x20)
568 			*status |= FE_HAS_LOCK | FE_HAS_SYNC;
569 	}
570 
571 	switch (state->config->status_mode) {
572 	case AU8522_DEMODLOCKING:
573 		dprintk("%s() DEMODLOCKING\n", __func__);
574 		if (*status & FE_HAS_VITERBI)
575 			*status |= FE_HAS_CARRIER | FE_HAS_SIGNAL;
576 		break;
577 	case AU8522_TUNERLOCKING:
578 		/* Get the tuner status */
579 		dprintk("%s() TUNERLOCKING\n", __func__);
580 		if (fe->ops.tuner_ops.get_status) {
581 			if (fe->ops.i2c_gate_ctrl)
582 				fe->ops.i2c_gate_ctrl(fe, 1);
583 
584 			fe->ops.tuner_ops.get_status(fe, &tuner_status);
585 
586 			if (fe->ops.i2c_gate_ctrl)
587 				fe->ops.i2c_gate_ctrl(fe, 0);
588 		}
589 		if (tuner_status)
590 			*status |= FE_HAS_CARRIER | FE_HAS_SIGNAL;
591 		break;
592 	}
593 	state->fe_status = *status;
594 
595 	if (*status & FE_HAS_LOCK)
596 		/* turn on LED, if it isn't on already */
597 		au8522_led_ctrl(state, -1);
598 	else
599 		/* turn off LED */
600 		au8522_led_ctrl(state, 0);
601 
602 	dprintk("%s() status 0x%08x\n", __func__, *status);
603 
604 	return 0;
605 }
606 
607 static int au8522_led_status(struct au8522_state *state, const u16 *snr)
608 {
609 	struct au8522_led_config *led_config = state->config->led_cfg;
610 	int led;
611 	u16 strong;
612 
613 	/* bail out if we can't control an LED */
614 	if (!led_config)
615 		return 0;
616 
617 	if (0 == (state->fe_status & FE_HAS_LOCK))
618 		return au8522_led_ctrl(state, 0);
619 	else if (state->current_modulation == QAM_256)
620 		strong = led_config->qam256_strong;
621 	else if (state->current_modulation == QAM_64)
622 		strong = led_config->qam64_strong;
623 	else /* (state->current_modulation == VSB_8) */
624 		strong = led_config->vsb8_strong;
625 
626 	if (*snr >= strong)
627 		led = 2;
628 	else
629 		led = 1;
630 
631 	if ((state->led_state) &&
632 	    (((strong < *snr) ? (*snr - strong) : (strong - *snr)) <= 10))
633 		/* snr didn't change enough to bother
634 		 * changing the color of the led */
635 		return 0;
636 
637 	return au8522_led_ctrl(state, led);
638 }
639 
640 static int au8522_read_snr(struct dvb_frontend *fe, u16 *snr)
641 {
642 	struct au8522_state *state = fe->demodulator_priv;
643 	int ret = -EINVAL;
644 
645 	dprintk("%s()\n", __func__);
646 
647 	if (state->current_modulation == QAM_256)
648 		ret = au8522_mse2snr_lookup(qam256_mse2snr_tab,
649 					    ARRAY_SIZE(qam256_mse2snr_tab),
650 					    au8522_readreg(state, 0x4522),
651 					    snr);
652 	else if (state->current_modulation == QAM_64)
653 		ret = au8522_mse2snr_lookup(qam64_mse2snr_tab,
654 					    ARRAY_SIZE(qam64_mse2snr_tab),
655 					    au8522_readreg(state, 0x4522),
656 					    snr);
657 	else /* VSB_8 */
658 		ret = au8522_mse2snr_lookup(vsb_mse2snr_tab,
659 					    ARRAY_SIZE(vsb_mse2snr_tab),
660 					    au8522_readreg(state, 0x4311),
661 					    snr);
662 
663 	if (state->config->led_cfg)
664 		au8522_led_status(state, snr);
665 
666 	return ret;
667 }
668 
669 static int au8522_read_signal_strength(struct dvb_frontend *fe,
670 				       u16 *signal_strength)
671 {
672 	/* borrowed from lgdt330x.c
673 	 *
674 	 * Calculate strength from SNR up to 35dB
675 	 * Even though the SNR can go higher than 35dB,
676 	 * there is some comfort factor in having a range of
677 	 * strong signals that can show at 100%
678 	 */
679 	u16 snr;
680 	u32 tmp;
681 	int ret = au8522_read_snr(fe, &snr);
682 
683 	*signal_strength = 0;
684 
685 	if (0 == ret) {
686 		/* The following calculation method was chosen
687 		 * purely for the sake of code re-use from the
688 		 * other demod drivers that use this method */
689 
690 		/* Convert from SNR in dB * 10 to 8.24 fixed-point */
691 		tmp = (snr * ((1 << 24) / 10));
692 
693 		/* Convert from 8.24 fixed-point to
694 		 * scale the range 0 - 35*2^24 into 0 - 65535*/
695 		if (tmp >= 8960 * 0x10000)
696 			*signal_strength = 0xffff;
697 		else
698 			*signal_strength = tmp / 8960;
699 	}
700 
701 	return ret;
702 }
703 
704 static int au8522_read_ucblocks(struct dvb_frontend *fe, u32 *ucblocks)
705 {
706 	struct au8522_state *state = fe->demodulator_priv;
707 
708 	if (state->current_modulation == VSB_8)
709 		*ucblocks = au8522_readreg(state, 0x4087);
710 	else
711 		*ucblocks = au8522_readreg(state, 0x4543);
712 
713 	return 0;
714 }
715 
716 static int au8522_read_ber(struct dvb_frontend *fe, u32 *ber)
717 {
718 	return au8522_read_ucblocks(fe, ber);
719 }
720 
721 static int au8522_get_frontend(struct dvb_frontend *fe)
722 {
723 	struct dtv_frontend_properties *c = &fe->dtv_property_cache;
724 	struct au8522_state *state = fe->demodulator_priv;
725 
726 	c->frequency = state->current_frequency;
727 	c->modulation = state->current_modulation;
728 
729 	return 0;
730 }
731 
732 static int au8522_get_tune_settings(struct dvb_frontend *fe,
733 				    struct dvb_frontend_tune_settings *tune)
734 {
735 	tune->min_delay_ms = 1000;
736 	return 0;
737 }
738 
739 static struct dvb_frontend_ops au8522_ops;
740 
741 
742 static void au8522_release(struct dvb_frontend *fe)
743 {
744 	struct au8522_state *state = fe->demodulator_priv;
745 	au8522_release_state(state);
746 }
747 
748 struct dvb_frontend *au8522_attach(const struct au8522_config *config,
749 				   struct i2c_adapter *i2c)
750 {
751 	struct au8522_state *state = NULL;
752 	int instance;
753 
754 	/* allocate memory for the internal state */
755 	instance = au8522_get_state(&state, i2c, config->demod_address);
756 	switch (instance) {
757 	case 0:
758 		dprintk("%s state allocation failed\n", __func__);
759 		break;
760 	case 1:
761 		/* new demod instance */
762 		dprintk("%s using new instance\n", __func__);
763 		break;
764 	default:
765 		/* existing demod instance */
766 		dprintk("%s using existing instance\n", __func__);
767 		break;
768 	}
769 
770 	/* setup the state */
771 	state->config = config;
772 	state->i2c = i2c;
773 	state->operational_mode = AU8522_DIGITAL_MODE;
774 
775 	/* create dvb_frontend */
776 	memcpy(&state->frontend.ops, &au8522_ops,
777 	       sizeof(struct dvb_frontend_ops));
778 	state->frontend.demodulator_priv = state;
779 
780 	state->frontend.ops.analog_ops.i2c_gate_ctrl = au8522_analog_i2c_gate_ctrl;
781 
782 	if (au8522_init(&state->frontend) != 0) {
783 		printk(KERN_ERR "%s: Failed to initialize correctly\n",
784 			__func__);
785 		goto error;
786 	}
787 
788 	/* Note: Leaving the I2C gate open here. */
789 	au8522_i2c_gate_ctrl(&state->frontend, 1);
790 
791 	return &state->frontend;
792 
793 error:
794 	au8522_release_state(state);
795 	return NULL;
796 }
797 EXPORT_SYMBOL(au8522_attach);
798 
799 static struct dvb_frontend_ops au8522_ops = {
800 	.delsys = { SYS_ATSC, SYS_DVBC_ANNEX_B },
801 	.info = {
802 		.name			= "Auvitek AU8522 QAM/8VSB Frontend",
803 		.frequency_min		= 54000000,
804 		.frequency_max		= 858000000,
805 		.frequency_stepsize	= 62500,
806 		.caps = FE_CAN_QAM_64 | FE_CAN_QAM_256 | FE_CAN_8VSB
807 	},
808 
809 	.init                 = au8522_init,
810 	.sleep                = au8522_sleep,
811 	.i2c_gate_ctrl        = au8522_i2c_gate_ctrl,
812 	.set_frontend         = au8522_set_frontend,
813 	.get_frontend         = au8522_get_frontend,
814 	.get_tune_settings    = au8522_get_tune_settings,
815 	.read_status          = au8522_read_status,
816 	.read_ber             = au8522_read_ber,
817 	.read_signal_strength = au8522_read_signal_strength,
818 	.read_snr             = au8522_read_snr,
819 	.read_ucblocks        = au8522_read_ucblocks,
820 	.release              = au8522_release,
821 };
822 
823 module_param(debug, int, 0644);
824 MODULE_PARM_DESC(debug, "Enable verbose debug messages");
825 
826 MODULE_DESCRIPTION("Auvitek AU8522 QAM-B/ATSC Demodulator driver");
827 MODULE_AUTHOR("Steven Toth");
828 MODULE_LICENSE("GPL");
829