1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * The Virtual DVB test driver serves as a reference DVB driver and helps
4  * validate the existing APIs in the media subsystem. It can also aid
5  * developers working on userspace applications.
6  *
7  * Copyright (C) 2020 Daniel W. S. Almeida
8  * Based on the example driver written by Emard <emard@softhome.net>
9  */
10 
11 #include <linux/errno.h>
12 #include <linux/i2c.h>
13 #include <linux/init.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/printk.h>
17 #include <linux/random.h>
18 #include <linux/ratelimit.h>
19 #include <linux/slab.h>
20 #include <linux/string.h>
21 #include <linux/workqueue.h>
22 
23 #include <media/dvb_frontend.h>
24 
25 #include "vidtv_demod.h"
26 
27 #define POLL_THRD_TIME 2000 /* ms */
28 
29 static const struct vidtv_demod_cnr_to_qual_s vidtv_demod_c_cnr_2_qual[] = {
30 	/* from libdvbv5 source code, in milli db */
31 	{ QAM_256, FEC_NONE,  34000, 38000},
32 	{ QAM_64,  FEC_NONE,  30000, 34000},
33 };
34 
35 static const struct vidtv_demod_cnr_to_qual_s vidtv_demod_s_cnr_2_qual[] = {
36 	/* from libdvbv5 source code, in milli db */
37 	{ QPSK, FEC_1_2,  7000, 10000},
38 	{ QPSK, FEC_2_3,  9000, 12000},
39 	{ QPSK, FEC_3_4, 10000, 13000},
40 	{ QPSK, FEC_5_6, 11000, 14000},
41 	{ QPSK, FEC_7_8, 12000, 15000},
42 };
43 
44 static const struct vidtv_demod_cnr_to_qual_s vidtv_demod_s2_cnr_2_qual[] = {
45 	/* from libdvbv5 source code, in milli db */
46 	{ QPSK,  FEC_1_2,   9000,  12000},
47 	{ QPSK,  FEC_2_3,  11000,  14000},
48 	{ QPSK,  FEC_3_4,  12000,  15000},
49 	{ QPSK,  FEC_5_6,  12000,  15000},
50 	{ QPSK,  FEC_8_9,  13000,  16000},
51 	{ QPSK,  FEC_9_10, 13500,  16500},
52 	{ PSK_8, FEC_2_3,  14500,  17500},
53 	{ PSK_8, FEC_3_4,  16000,  19000},
54 	{ PSK_8, FEC_5_6,  17500,  20500},
55 	{ PSK_8, FEC_8_9,  19000,  22000},
56 };
57 
58 static const struct vidtv_demod_cnr_to_qual_s vidtv_demod_t_cnr_2_qual[] = {
59 	/* from libdvbv5 source code, in milli db*/
60 	{   QPSK, FEC_1_2,  4100,  5900},
61 	{   QPSK, FEC_2_3,  6100,  9600},
62 	{   QPSK, FEC_3_4,  7200, 12400},
63 	{   QPSK, FEC_5_6,  8500, 15600},
64 	{   QPSK, FEC_7_8,  9200, 17500},
65 	{ QAM_16, FEC_1_2,  9800, 11800},
66 	{ QAM_16, FEC_2_3, 12100, 15300},
67 	{ QAM_16, FEC_3_4, 13400, 18100},
68 	{ QAM_16, FEC_5_6, 14800, 21300},
69 	{ QAM_16, FEC_7_8, 15700, 23600},
70 	{ QAM_64, FEC_1_2, 14000, 16000},
71 	{ QAM_64, FEC_2_3, 19900, 25400},
72 	{ QAM_64, FEC_3_4, 24900, 27900},
73 	{ QAM_64, FEC_5_6, 21300, 23300},
74 	{ QAM_64, FEC_7_8, 22000, 24000},
75 };
76 
77 static const struct vidtv_demod_cnr_to_qual_s *vidtv_match_cnr_s(struct dvb_frontend *fe)
78 {
79 	const struct vidtv_demod_cnr_to_qual_s *cnr2qual = NULL;
80 	struct device *dev = fe->dvb->device;
81 	struct dtv_frontend_properties *c;
82 	u32 array_size = 0;
83 	u32 i;
84 
85 	c = &fe->dtv_property_cache;
86 
87 	switch (c->delivery_system) {
88 	case SYS_DVBT:
89 	case SYS_DVBT2:
90 		cnr2qual   = vidtv_demod_t_cnr_2_qual;
91 		array_size = ARRAY_SIZE(vidtv_demod_t_cnr_2_qual);
92 		break;
93 
94 	case SYS_DVBS:
95 		cnr2qual   = vidtv_demod_s_cnr_2_qual;
96 		array_size = ARRAY_SIZE(vidtv_demod_s_cnr_2_qual);
97 		break;
98 
99 	case SYS_DVBS2:
100 		cnr2qual   = vidtv_demod_s2_cnr_2_qual;
101 		array_size = ARRAY_SIZE(vidtv_demod_s2_cnr_2_qual);
102 		break;
103 
104 	case SYS_DVBC_ANNEX_A:
105 		cnr2qual   = vidtv_demod_c_cnr_2_qual;
106 		array_size = ARRAY_SIZE(vidtv_demod_c_cnr_2_qual);
107 		break;
108 
109 	default:
110 		dev_warn_ratelimited(dev,
111 				     "%s: unsupported delivery system: %u\n",
112 				     __func__,
113 				     c->delivery_system);
114 		break;
115 	}
116 
117 	for (i = 0; i < array_size; i++)
118 		if (cnr2qual[i].modulation == c->modulation &&
119 		    cnr2qual[i].fec == c->fec_inner)
120 			return &cnr2qual[i];
121 
122 	return NULL; /* not found */
123 }
124 
125 static void vidtv_clean_stats(struct dvb_frontend *fe)
126 {
127 	struct dtv_frontend_properties *c = &fe->dtv_property_cache;
128 
129 	/* Fill the length of each status counter */
130 
131 	/* Signal is always available */
132 	c->strength.len = 1;
133 	c->strength.stat[0].scale = FE_SCALE_DECIBEL;
134 	c->strength.stat[0].svalue = 0;
135 
136 	/* Usually available only after Viterbi lock */
137 	c->cnr.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
138 	c->cnr.stat[0].svalue = 0;
139 	c->cnr.len = 1;
140 
141 	/* Those depends on full lock */
142 	c->pre_bit_error.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
143 	c->pre_bit_error.stat[0].uvalue = 0;
144 	c->pre_bit_error.len = 1;
145 	c->pre_bit_count.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
146 	c->pre_bit_count.stat[0].uvalue = 0;
147 	c->pre_bit_count.len = 1;
148 	c->post_bit_error.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
149 	c->post_bit_error.stat[0].uvalue = 0;
150 	c->post_bit_error.len = 1;
151 	c->post_bit_count.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
152 	c->post_bit_count.stat[0].uvalue = 0;
153 	c->post_bit_count.len = 1;
154 	c->block_error.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
155 	c->block_error.stat[0].uvalue = 0;
156 	c->block_error.len = 1;
157 	c->block_count.stat[0].scale = FE_SCALE_NOT_AVAILABLE;
158 	c->block_count.stat[0].uvalue = 0;
159 	c->block_count.len = 1;
160 }
161 
162 static void vidtv_demod_update_stats(struct dvb_frontend *fe)
163 {
164 	struct dtv_frontend_properties *c = &fe->dtv_property_cache;
165 	struct vidtv_demod_state *state = fe->demodulator_priv;
166 	u32 scale;
167 
168 	if (state->status & FE_HAS_LOCK) {
169 		scale = FE_SCALE_COUNTER;
170 		c->cnr.stat[0].scale = FE_SCALE_DECIBEL;
171 	} else {
172 		scale = FE_SCALE_NOT_AVAILABLE;
173 		c->cnr.stat[0].scale = scale;
174 	}
175 
176 	c->pre_bit_error.stat[0].scale = scale;
177 	c->pre_bit_count.stat[0].scale = scale;
178 	c->post_bit_error.stat[0].scale = scale;
179 	c->post_bit_count.stat[0].scale = scale;
180 	c->block_error.stat[0].scale = scale;
181 	c->block_count.stat[0].scale = scale;
182 
183 	/*
184 	 * Add a 0.5% of randomness at the signal strength and CNR,
185 	 * and make them different, as we want to have something closer
186 	 * to a real case scenario.
187 	 *
188 	 * Also, usually, signal strength is a negative number in dBm.
189 	 */
190 	c->strength.stat[0].svalue = state->tuner_cnr;
191 	c->strength.stat[0].svalue -= get_random_u32_below(state->tuner_cnr / 50);
192 	c->strength.stat[0].svalue -= 68000; /* Adjust to a better range */
193 
194 	c->cnr.stat[0].svalue = state->tuner_cnr;
195 	c->cnr.stat[0].svalue -= get_random_u32_below(state->tuner_cnr / 50);
196 }
197 
198 static int vidtv_demod_read_status(struct dvb_frontend *fe,
199 				   enum fe_status *status)
200 {
201 	struct vidtv_demod_state *state = fe->demodulator_priv;
202 	const struct vidtv_demod_cnr_to_qual_s *cnr2qual = NULL;
203 	struct vidtv_demod_config *config = &state->config;
204 	u16 snr = 0;
205 
206 	/* Simulate random lost of signal due to a bad-tuned channel */
207 	cnr2qual = vidtv_match_cnr_s(&state->frontend);
208 
209 	if (cnr2qual && state->tuner_cnr < cnr2qual->cnr_good &&
210 	    state->frontend.ops.tuner_ops.get_rf_strength) {
211 		state->frontend.ops.tuner_ops.get_rf_strength(&state->frontend,
212 							      &snr);
213 
214 		if (snr < cnr2qual->cnr_ok) {
215 			/* eventually lose the TS lock */
216 			if (get_random_u32_below(100) < config->drop_tslock_prob_on_low_snr)
217 				state->status = 0;
218 		} else {
219 			/* recover if the signal improves */
220 			if (get_random_u32_below(100) <
221 			    config->recover_tslock_prob_on_good_snr)
222 				state->status = FE_HAS_SIGNAL  |
223 						FE_HAS_CARRIER |
224 						FE_HAS_VITERBI |
225 						FE_HAS_SYNC    |
226 						FE_HAS_LOCK;
227 		}
228 	}
229 
230 	vidtv_demod_update_stats(&state->frontend);
231 
232 	*status = state->status;
233 
234 	return 0;
235 }
236 
237 static int vidtv_demod_read_signal_strength(struct dvb_frontend *fe,
238 					    u16 *strength)
239 {
240 	struct dtv_frontend_properties *c = &fe->dtv_property_cache;
241 
242 	*strength = c->strength.stat[0].uvalue;
243 
244 	return 0;
245 }
246 
247 /*
248  * NOTE:
249  * This is implemented here just to be used as an example for real
250  * demod drivers.
251  *
252  * Should only be implemented if it actually reads something from the hardware.
253  * Also, it should check for the locks, in order to avoid report wrong data
254  * to userspace.
255  */
256 static int vidtv_demod_get_frontend(struct dvb_frontend *fe,
257 				    struct dtv_frontend_properties *p)
258 {
259 	return 0;
260 }
261 
262 static int vidtv_demod_set_frontend(struct dvb_frontend *fe)
263 {
264 	struct vidtv_demod_state *state = fe->demodulator_priv;
265 	u32 tuner_status = 0;
266 	int ret;
267 
268 	if (!fe->ops.tuner_ops.set_params)
269 		return 0;
270 
271 	fe->ops.tuner_ops.set_params(fe);
272 
273 	/* store the CNR returned by the tuner */
274 	ret = fe->ops.tuner_ops.get_rf_strength(fe, &state->tuner_cnr);
275 	if (ret < 0)
276 		return ret;
277 
278 	fe->ops.tuner_ops.get_status(fe, &tuner_status);
279 	state->status = (state->tuner_cnr > 0) ?  FE_HAS_SIGNAL  |
280 						    FE_HAS_CARRIER |
281 						    FE_HAS_VITERBI |
282 						    FE_HAS_SYNC    |
283 						    FE_HAS_LOCK	 :
284 						    0;
285 
286 	vidtv_demod_update_stats(fe);
287 
288 	if (fe->ops.i2c_gate_ctrl)
289 		fe->ops.i2c_gate_ctrl(fe, 0);
290 
291 	return 0;
292 }
293 
294 /*
295  * NOTE:
296  * This is implemented here just to be used as an example for real
297  * demod drivers.
298  *
299  * Should only be implemented if the demod has support for DVB-S or DVB-S2
300  */
301 static int vidtv_demod_set_tone(struct dvb_frontend *fe,
302 				enum fe_sec_tone_mode tone)
303 {
304 	return 0;
305 }
306 
307 /*
308  * NOTE:
309  * This is implemented here just to be used as an example for real
310  * demod drivers.
311  *
312  * Should only be implemented if the demod has support for DVB-S or DVB-S2
313  */
314 static int vidtv_demod_set_voltage(struct dvb_frontend *fe,
315 				   enum fe_sec_voltage voltage)
316 {
317 	return 0;
318 }
319 
320 /*
321  * NOTE:
322  * This is implemented here just to be used as an example for real
323  * demod drivers.
324  *
325  * Should only be implemented if the demod has support for DVB-S or DVB-S2
326  */
327 static int vidtv_send_diseqc_msg(struct dvb_frontend *fe,
328 				 struct dvb_diseqc_master_cmd *cmd)
329 {
330 	return 0;
331 }
332 
333 /*
334  * NOTE:
335  * This is implemented here just to be used as an example for real
336  * demod drivers.
337  *
338  * Should only be implemented if the demod has support for DVB-S or DVB-S2
339  */
340 static int vidtv_diseqc_send_burst(struct dvb_frontend *fe,
341 				   enum fe_sec_mini_cmd burst)
342 {
343 	return 0;
344 }
345 
346 static void vidtv_demod_release(struct dvb_frontend *fe)
347 {
348 	struct vidtv_demod_state *state = fe->demodulator_priv;
349 
350 	kfree(state);
351 }
352 
353 static const struct dvb_frontend_ops vidtv_demod_ops = {
354 	.delsys = {
355 		SYS_DVBT,
356 		SYS_DVBT2,
357 		SYS_DVBC_ANNEX_A,
358 		SYS_DVBS,
359 		SYS_DVBS2,
360 	},
361 
362 	.info = {
363 		.name                   = "Dummy demod for DVB-T/T2/C/S/S2",
364 		.frequency_min_hz       = 51 * MHz,
365 		.frequency_max_hz       = 2150 * MHz,
366 		.frequency_stepsize_hz  = 62500,
367 		.frequency_tolerance_hz = 29500 * kHz,
368 		.symbol_rate_min        = 1000000,
369 		.symbol_rate_max        = 45000000,
370 
371 		.caps = FE_CAN_FEC_1_2 |
372 			FE_CAN_FEC_2_3 |
373 			FE_CAN_FEC_3_4 |
374 			FE_CAN_FEC_4_5 |
375 			FE_CAN_FEC_5_6 |
376 			FE_CAN_FEC_6_7 |
377 			FE_CAN_FEC_7_8 |
378 			FE_CAN_FEC_8_9 |
379 			FE_CAN_QAM_16 |
380 			FE_CAN_QAM_64 |
381 			FE_CAN_QAM_32 |
382 			FE_CAN_QAM_128 |
383 			FE_CAN_QAM_256 |
384 			FE_CAN_QAM_AUTO |
385 			FE_CAN_QPSK |
386 			FE_CAN_FEC_AUTO |
387 			FE_CAN_INVERSION_AUTO |
388 			FE_CAN_TRANSMISSION_MODE_AUTO |
389 			FE_CAN_GUARD_INTERVAL_AUTO |
390 			FE_CAN_HIERARCHY_AUTO,
391 	},
392 
393 	.release = vidtv_demod_release,
394 
395 	.set_frontend = vidtv_demod_set_frontend,
396 	.get_frontend = vidtv_demod_get_frontend,
397 
398 	.read_status          = vidtv_demod_read_status,
399 	.read_signal_strength = vidtv_demod_read_signal_strength,
400 
401 	/* For DVB-S/S2 */
402 	.set_voltage		= vidtv_demod_set_voltage,
403 	.set_tone		= vidtv_demod_set_tone,
404 	.diseqc_send_master_cmd	= vidtv_send_diseqc_msg,
405 	.diseqc_send_burst	= vidtv_diseqc_send_burst,
406 
407 };
408 
409 static const struct i2c_device_id vidtv_demod_i2c_id_table[] = {
410 	{"dvb_vidtv_demod", 0},
411 	{}
412 };
413 MODULE_DEVICE_TABLE(i2c, vidtv_demod_i2c_id_table);
414 
415 static int vidtv_demod_i2c_probe(struct i2c_client *client)
416 {
417 	struct vidtv_tuner_config *config = client->dev.platform_data;
418 	struct vidtv_demod_state *state;
419 
420 	/* allocate memory for the internal state */
421 	state = kzalloc(sizeof(*state), GFP_KERNEL);
422 	if (!state)
423 		return -ENOMEM;
424 
425 	/* create dvb_frontend */
426 	memcpy(&state->frontend.ops,
427 	       &vidtv_demod_ops,
428 	       sizeof(struct dvb_frontend_ops));
429 
430 	memcpy(&state->config, config, sizeof(state->config));
431 
432 	state->frontend.demodulator_priv = state;
433 	i2c_set_clientdata(client, state);
434 
435 	vidtv_clean_stats(&state->frontend);
436 
437 	return 0;
438 }
439 
440 static void vidtv_demod_i2c_remove(struct i2c_client *client)
441 {
442 	struct vidtv_demod_state *state = i2c_get_clientdata(client);
443 
444 	kfree(state);
445 }
446 
447 static struct i2c_driver vidtv_demod_i2c_driver = {
448 	.driver = {
449 		.name                = "dvb_vidtv_demod",
450 		.suppress_bind_attrs = true,
451 	},
452 	.probe    = vidtv_demod_i2c_probe,
453 	.remove   = vidtv_demod_i2c_remove,
454 	.id_table = vidtv_demod_i2c_id_table,
455 };
456 
457 module_i2c_driver(vidtv_demod_i2c_driver);
458 
459 MODULE_DESCRIPTION("Virtual DVB Demodulator Driver");
460 MODULE_AUTHOR("Daniel W. S. Almeida");
461 MODULE_LICENSE("GPL");
462