media: vidtv: implement a demodulator driver (f5ffc3b6) · Commits · 戴 / test

drivers/media/test-drivers/vidtv/Makefile

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		# SPDX-License-Identifier: GPL-2.0

		dvb-vidtv-tuner-objs := vidtv_tuner.o
		dvb-vidtv-demod-objs := vidtv_demod.o

		obj-$(CONFIG_DVB_VIDTV) += dvb-vidtv-tuner.o
		obj-$(CONFIG_DVB_VIDTV) += dvb-vidtv-tuner.o dvb-vidtv-demod.o

drivers/media/test-drivers/vidtv/vidtv_demod.c

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		// SPDX-License-Identifier: GPL-2.0-or-later
		/*
		* The Virtual DVB test driver serves as a reference DVB driver and helps
		* validate the existing APIs in the media subsystem. It can also aid
		* developers working on userspace applications.
		*
		* Copyright (C) 2020 Daniel W. S. Almeida
		* Based on the example driver written by Emard <emard@softhome.net>
		*/

		#include <linux/errno.h>
		#include <linux/i2c.h>
		#include <linux/init.h>
		#include <linux/kernel.h>
		#include <linux/module.h>
		#include <linux/printk.h>
		#include <linux/random.h>
		#include <linux/ratelimit.h>
		#include <linux/slab.h>
		#include <linux/string.h>
		#include <linux/workqueue.h>
		#include <media/dvb_frontend.h>

		#include "vidtv_demod.h"

		#define POLL_THRD_TIME 2000 /* ms */

		static const struct vidtv_demod_cnr_to_qual_s vidtv_demod_c_cnr_2_qual[] = {
		/* from libdvbv5 source code, in milli db */
		{ QAM_256, FEC_NONE, 34000, 38000},
		{ QAM_64, FEC_NONE, 30000, 34000},
		};

		static const struct vidtv_demod_cnr_to_qual_s vidtv_demod_s_cnr_2_qual[] = {
		/* from libdvbv5 source code, in milli db */
		{ QPSK, FEC_1_2, 7000, 10000},
		{ QPSK, FEC_2_3, 9000, 12000},
		{ QPSK, FEC_3_4, 10000, 13000},
		{ QPSK, FEC_5_6, 11000, 14000},
		{ QPSK, FEC_7_8, 12000, 15000},
		};

		static const struct vidtv_demod_cnr_to_qual_s vidtv_demod_s2_cnr_2_qual[] = {
		/* from libdvbv5 source code, in milli db */
		{ QPSK, FEC_1_2, 9000, 12000},
		{ QPSK, FEC_2_3, 11000, 14000},
		{ QPSK, FEC_3_4, 12000, 15000},
		{ QPSK, FEC_5_6, 12000, 15000},
		{ QPSK, FEC_8_9, 13000, 16000},
		{ QPSK, FEC_9_10, 13500, 16500},
		{ PSK_8, FEC_2_3, 14500, 17500},
		{ PSK_8, FEC_3_4, 16000, 19000},
		{ PSK_8, FEC_5_6, 17500, 20500},
		{ PSK_8, FEC_8_9, 19000, 22000},
		};

		static const struct vidtv_demod_cnr_to_qual_s vidtv_demod_t_cnr_2_qual[] = {
		/* from libdvbv5 source code, in milli db*/
		{ QPSK, FEC_1_2, 4100, 5900},
		{ QPSK, FEC_2_3, 6100, 9600},
		{ QPSK, FEC_3_4, 7200, 12400},
		{ QPSK, FEC_5_6, 8500, 15600},
		{ QPSK, FEC_7_8, 9200, 17500},
		{ QAM_16, FEC_1_2, 9800, 11800},
		{ QAM_16, FEC_2_3, 12100, 15300},
		{ QAM_16, FEC_3_4, 13400, 18100},
		{ QAM_16, FEC_5_6, 14800, 21300},
		{ QAM_16, FEC_7_8, 15700, 23600},
		{ QAM_64, FEC_1_2, 14000, 16000},
		{ QAM_64, FEC_2_3, 19900, 25400},
		{ QAM_64, FEC_3_4, 24900, 27900},
		{ QAM_64, FEC_5_6, 21300, 23300},
		{ QAM_64, FEC_7_8, 22000, 24000},
		};

		static const struct vidtv_demod_cnr_to_qual_s
		vidtv_match_cnr_s(struct dvb_frontend fe)
		{
		struct dtv_frontend_properties *c;
		const struct vidtv_demod_cnr_to_qual_s *cnr2qual = NULL;
		u32 array_size = 0;
		u32 i;

		c = &fe->dtv_property_cache;

		switch (c->delivery_system) {
		case SYS_DVBT:
		case SYS_DVBT2:
		cnr2qual = vidtv_demod_t_cnr_2_qual;
		array_size = ARRAY_SIZE(vidtv_demod_t_cnr_2_qual);
		break;

		case SYS_DVBS:
		cnr2qual = vidtv_demod_s_cnr_2_qual;
		array_size = ARRAY_SIZE(vidtv_demod_s_cnr_2_qual);
		break;

		case SYS_DVBS2:
		cnr2qual = vidtv_demod_s2_cnr_2_qual;
		array_size = ARRAY_SIZE(vidtv_demod_s2_cnr_2_qual);
		break;

		case SYS_DVBC_ANNEX_A:
		cnr2qual = vidtv_demod_c_cnr_2_qual;
		array_size = ARRAY_SIZE(vidtv_demod_c_cnr_2_qual);
		break;

		default:
		pr_warn_ratelimited("%s: unsupported delivery system: %u\n",
		__func__,
		c->delivery_system);
		break;
		}

		for (i = 0; i < array_size; i++)
		if (cnr2qual[i].modulation == c->modulation &&
		cnr2qual[i].fec == c->fec_inner)
		return &cnr2qual[i];

		return NULL; /* not found */
		}

		static void vidtv_demod_poll_snr_handler(struct work_struct *work)
		{
		/*
		* periodically check the signal quality and eventually
		* lose the TS lock if it dips too low
		*/
		struct vidtv_demod_state *state;
		const struct vidtv_demod_cnr_to_qual_s *cnr2qual = NULL;
		struct vidtv_demod_config *config;
		u16 snr = 0;

		state = container_of(work, struct vidtv_demod_state, poll_snr.work);
		config = &state->config;

		if (!state->frontend.ops.tuner_ops.get_rf_strength)
		return;

		state->frontend.ops.tuner_ops.get_rf_strength(&state->frontend, &snr);

		cnr2qual = vidtv_match_cnr_s(&state->frontend);
		if (!cnr2qual)
		return;

		if (snr < cnr2qual->cnr_ok) {
		/* eventually lose the TS lock */
		if (prandom_u32_max(100) < config->drop_tslock_prob_on_low_snr)
		state->status = 0;
		} else {
		/* recover if the signal improves */
		if (prandom_u32_max(100) <
		config->recover_tslock_prob_on_good_snr)
		state->status = FE_HAS_SIGNAL \|
		FE_HAS_CARRIER \|
		FE_HAS_VITERBI \|
		FE_HAS_SYNC \|
		FE_HAS_LOCK;
		}

		schedule_delayed_work(&state->poll_snr,
		msecs_to_jiffies(POLL_THRD_TIME));
		}

		static int vidtv_demod_read_status(struct dvb_frontend *fe,
		enum fe_status *status)
		{
		struct vidtv_demod_state *state = fe->demodulator_priv;

		*status = state->status;

		return 0;
		}

		static int vidtv_demod_read_ber(struct dvb_frontend fe, u32 ber)
		{
		*ber = 0;
		return 0;
		}

		static int vidtv_demod_read_signal_strength(struct dvb_frontend *fe,
		u16 *strength)
		{
		*strength = 0;
		return 0;
		}

		static int vidtv_demod_read_snr(struct dvb_frontend fe, u16 snr)
		{
		*snr = 0;
		return 0;
		}

		static int vidtv_demod_read_ucblocks(struct dvb_frontend fe, u32 ucblocks)
		{
		*ucblocks = 0;
		return 0;
		}

		/*
		* NOTE:
		* This is implemented here just to be used as an example for real
		* demod drivers.
		*
		* Should only be implemented if it actually reads something from the hardware.
		* Also, it should check for the locks, in order to avoid report wrong data
		* to userspace.
		*/
		static int vidtv_demod_get_frontend(struct dvb_frontend *fe,
		struct dtv_frontend_properties *p)
		{
		return 0;
		}

		static int vidtv_demod_set_frontend(struct dvb_frontend *fe)
		{
		struct vidtv_demod_state *state = fe->demodulator_priv;
		const struct vidtv_demod_cnr_to_qual_s *cnr2qual = NULL;
		u32 tuner_status = 0;

		if (fe->ops.tuner_ops.set_params) {
		fe->ops.tuner_ops.set_params(fe);

		/* store the CNR returned by the tuner */
		fe->ops.tuner_ops.get_rf_strength(fe, &state->tuner_cnr);

		fe->ops.tuner_ops.get_status(fe, &tuner_status);
		state->status = (state->tuner_cnr > 0) ? FE_HAS_SIGNAL \|
		FE_HAS_CARRIER \|
		FE_HAS_VITERBI \|
		FE_HAS_SYNC \|
		FE_HAS_LOCK :
		0;
		cnr2qual = vidtv_match_cnr_s(fe);

		/* signal isn't good: might lose the lock eventually */
		if (tuner_status == TUNER_STATUS_LOCKED &&
		state->tuner_cnr < cnr2qual->cnr_good) {
		schedule_delayed_work(&state->poll_snr,
		msecs_to_jiffies(POLL_THRD_TIME));

		state->poll_snr_thread_running = true;
		}

		if (fe->ops.i2c_gate_ctrl)
		fe->ops.i2c_gate_ctrl(fe, 0);
		}

		return 0;
		}

		static int vidtv_demod_sleep(struct dvb_frontend *fe)
		{
		struct vidtv_demod_state *state = fe->demodulator_priv;

		if (state->poll_snr_thread_running) {
		cancel_delayed_work_sync(&state->poll_snr);
		state->poll_snr_thread_running = false;
		state->poll_snr_thread_restart = true;
		}
		return 0;
		}

		static int vidtv_demod_init(struct dvb_frontend *fe)
		{
		struct vidtv_demod_state *state = fe->demodulator_priv;
		u32 tuner_status = 0;

		if (state->cold_start)
		INIT_DELAYED_WORK(&state->poll_snr,
		&vidtv_demod_poll_snr_handler);

		/*
		* At resume, start the snr poll thread only if it was suspended with
		* the thread running. Extra care should be taken here, as some tuner
		* status change might happen at resume time (for example, due to an
		* ioctl syscall to set_frontend, or due to a release syscall).
		*/
		fe->ops.tuner_ops.get_status(fe, &tuner_status);

		if (tuner_status == TUNER_STATUS_LOCKED &&
		state->poll_snr_thread_restart) {
		schedule_delayed_work(&state->poll_snr,
		msecs_to_jiffies(POLL_THRD_TIME));

		state->poll_snr_thread_restart = false;
		}

		state->cold_start = false;
		return 0;
		}

		/*
		* NOTE:
		* This is implemented here just to be used as an example for real
		* demod drivers.
		*
		* Should only be implemented if the demod has support for DVB-S or DVB-S2
		*/
		static int vidtv_demod_set_tone(struct dvb_frontend *fe,
		enum fe_sec_tone_mode tone)
		{
		return 0;
		}

		/*
		* NOTE:
		* This is implemented here just to be used as an example for real
		* demod drivers.
		*
		* Should only be implemented if the demod has support for DVB-S or DVB-S2
		*/
		static int vidtv_demod_set_voltage(struct dvb_frontend *fe,
		enum fe_sec_voltage voltage)
		{
		return 0;
		}

		static void vidtv_demod_release(struct dvb_frontend *fe)
		{
		struct vidtv_demod_state *state = fe->demodulator_priv;

		if (state->poll_snr_thread_running)
		cancel_delayed_work_sync(&state->poll_snr);

		kfree(state);
		}

		static const struct dvb_frontend_ops vidtv_demod_ops = {
		.delsys = {
		SYS_DVBT,
		SYS_DVBT2,
		SYS_DVBC_ANNEX_A,
		SYS_DVBS,
		SYS_DVBS2,
		},

		.info = {
		.name = "Dummy demod for DVB-T/T2/C/S/S2",
		.frequency_min_hz = 51 * MHz,
		.frequency_max_hz = 2150 * MHz,
		.frequency_stepsize_hz = 62500,
		.frequency_tolerance_hz = 29500 * kHz,
		.symbol_rate_min = 1000000,
		.symbol_rate_max = 45000000,

		.caps = FE_CAN_FEC_1_2 \|
		FE_CAN_FEC_2_3 \|
		FE_CAN_FEC_3_4 \|
		FE_CAN_FEC_4_5 \|
		FE_CAN_FEC_5_6 \|
		FE_CAN_FEC_6_7 \|
		FE_CAN_FEC_7_8 \|
		FE_CAN_FEC_8_9 \|
		FE_CAN_QAM_16 \|
		FE_CAN_QAM_64 \|
		FE_CAN_QAM_32 \|
		FE_CAN_QAM_128 \|
		FE_CAN_QAM_256 \|
		FE_CAN_QAM_AUTO \|
		FE_CAN_QPSK \|
		FE_CAN_FEC_AUTO \|
		FE_CAN_INVERSION_AUTO \|
		FE_CAN_TRANSMISSION_MODE_AUTO \|
		FE_CAN_GUARD_INTERVAL_AUTO \|
		FE_CAN_HIERARCHY_AUTO,
		},

		.release = vidtv_demod_release,

		.init = vidtv_demod_init,
		.sleep = vidtv_demod_sleep,

		.set_frontend = vidtv_demod_set_frontend,
		.get_frontend = vidtv_demod_get_frontend,

		.read_status = vidtv_demod_read_status,
		.read_ber = vidtv_demod_read_ber,
		.read_signal_strength = vidtv_demod_read_signal_strength,
		.read_snr = vidtv_demod_read_snr,
		.read_ucblocks = vidtv_demod_read_ucblocks,

		/* For DVB-S/S2 */
		.set_voltage = vidtv_demod_set_voltage,
		.set_tone = vidtv_demod_set_tone,
		};

		static const struct i2c_device_id vidtv_demod_i2c_id_table[] = {
		{"dvb_vidtv_demod", 0},
		{}
		};
		MODULE_DEVICE_TABLE(i2c, vidtv_demod_i2c_id_table);

		static int vidtv_demod_i2c_probe(struct i2c_client *client,
		const struct i2c_device_id *id)
		{
		struct vidtv_demod_state *state;

		/* allocate memory for the internal state */
		state = kzalloc(sizeof(*state), GFP_KERNEL);
		if (!state)
		return -ENOMEM;

		/* create dvb_frontend */
		memcpy(&state->frontend.ops,
		&vidtv_demod_ops,
		sizeof(struct dvb_frontend_ops));

		state->frontend.demodulator_priv = state;
		i2c_set_clientdata(client, state);

		return 0;
		}

		static int vidtv_demod_i2c_remove(struct i2c_client *client)
		{
		struct vidtv_demod_state *state = i2c_get_clientdata(client);

		memset(&state->frontend.ops, 0, sizeof(struct dvb_frontend_ops));
		state->frontend.demodulator_priv = NULL;
		kfree(state);

		return 0;
		}

		static struct i2c_driver vidtv_demod_i2c_driver = {
		.driver = {
		.name = "dvb_vidtv_demod",
		.suppress_bind_attrs = true,
		},
		.probe = vidtv_demod_i2c_probe,
		.remove = vidtv_demod_i2c_remove,
		.id_table = vidtv_demod_i2c_id_table,
		};

		module_i2c_driver(vidtv_demod_i2c_driver);

		MODULE_DESCRIPTION("Virtual DVB Demodulator Driver");
		MODULE_AUTHOR("Daniel W. S. Almeida");
		MODULE_LICENSE("GPL");

drivers/media/test-drivers/vidtv/vidtv_demod.h

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		/* SPDX-License-Identifier: GPL-2.0-or-later */
		/*
		* The Virtual DTV test driver serves as a reference DVB driver and helps
		* validate the existing APIs in the media subsystem. It can also aid
		* developers working on userspace applications.
		*
		* Copyright (C) 2020 Daniel W. S. Almeida
		* Based on the example driver written by Emard <emard@softhome.net>
		*/

		#ifndef VIDTV_DEMOD_H
		#define VIDTV_DEMOD_H

		#include <linux/dvb/frontend.h>
		#include <media/dvb_frontend.h>

		/**
		* struct vidtv_demod_cnr_to_qual_s - Map CNR values to a given combination of
		* modulation and fec_inner
		* @modulation: see enum fe_modulation
		* @fec: see enum fe_fec_rate
		*
		* This struct matches values for 'good' and 'ok' CNRs given the combination
		* of modulation and fec_inner in use. We might simulate some noise if the
		* signal quality is not too good.
		*
		* The values were taken from libdvbv5.
		*/
		struct vidtv_demod_cnr_to_qual_s {
		u32 modulation;
		u32 fec;
		u32 cnr_ok;
		u32 cnr_good;
		};

		/**
		* struct vidtv_demod_config - Configuration used to init the demod
		* @drop_tslock_prob_on_low_snr: probability of losing the lock due to low snr
		* @recover_tslock_prob_on_good_snr: probability of recovering when the signal
		* improves
		*
		* The configuration used to init the demodulator module, usually filled
		* by a bridge driver. For vidtv, this is filled by vidtv_bridge before the
		* demodulator module is probed.
		*/
		struct vidtv_demod_config {
		u8 drop_tslock_prob_on_low_snr;
		u8 recover_tslock_prob_on_good_snr;
		};

		/**
		* struct vidtv_demod_state - The demodulator state
		* @frontend: The frontend structure allocated by the demod.
		* @config: The config used to init the demod.
		* @poll_snr: The task responsible for periodically checking the simulated
		* signal quality, eventually dropping or reacquiring the TS lock.
		* @status: the demod status.
		* @cold_start: Whether the demod has not been init yet.
		* @poll_snr_thread_running: Whether the task responsible for periodically
		* checking the simulated signal quality is running.
		* @poll_snr_thread_restart: Whether we should restart the poll_snr task.
		*/
		struct vidtv_demod_state {
		struct dvb_frontend frontend;
		struct vidtv_demod_config config;
		struct delayed_work poll_snr;
		enum fe_status status;
		u16 tuner_cnr;
		bool cold_start;
		bool poll_snr_thread_running;
		bool poll_snr_thread_restart;
		};
		#endif // VIDTV_DEMOD_H

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