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
29static 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
35static 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
44static 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
58static 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
77static 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
125static 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
162static 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
198static 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
237static 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 */
256static int vidtv_demod_get_frontend(struct dvb_frontend *fe,
257				    struct dtv_frontend_properties *p)
258{
259	return 0;
260}
261
262static 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 */
301static 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 */
314static 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 */
327static 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 */
340static int vidtv_diseqc_send_burst(struct dvb_frontend *fe,
341				   enum fe_sec_mini_cmd burst)
342{
343	return 0;
344}
345
346static void vidtv_demod_release(struct dvb_frontend *fe)
347{
348	struct vidtv_demod_state *state = fe->demodulator_priv;
349
350	kfree(state);
351}
352
353static 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
409static const struct i2c_device_id vidtv_demod_i2c_id_table[] = {
410	{"dvb_vidtv_demod", 0},
411	{}
412};
413MODULE_DEVICE_TABLE(i2c, vidtv_demod_i2c_id_table);
414
415static 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
440static 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
447static 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
457module_i2c_driver(vidtv_demod_i2c_driver);
458
459MODULE_DESCRIPTION("Virtual DVB Demodulator Driver");
460MODULE_AUTHOR("Daniel W. S. Almeida");
461MODULE_LICENSE("GPL");
462