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Date:   Sun, 3 May 2020 11:13:38 +0200
From:   Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
To:     "Daniel W. S. Almeida" <dwlsalmeida@gmail.com>
Cc:     sean@mess.org, kstewart@linuxfoundation.org, allison@lohutok.net,
        tglx@linutronix.de, linux-media@vger.kernel.org,
        skhan@linuxfoundation.org,
        linux-kernel-mentees@lists.linuxfoundation.org,
        linux-kernel@vger.kernel.org
Subject: Re: [RFC, WIP, v4 11/11] media: vidtv: Add a MPEG Transport Stream
 Multiplexer
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In-Reply-To: <20200502032216.197977-12-dwlsalmeida@gmail.com>
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        <20200502032216.197977-12-dwlsalmeida@gmail.com>
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Em Sat,  2 May 2020 00:22:16 -0300
"Daniel W. S. Almeida" <dwlsalmeida@gmail.com> escreveu:

> From: "Daniel W. S. Almeida" <dwlsalmeida@gmail.com>
> 
> Add a MPEG Transport Stream multiplexer responsible for polling encoders,
> interleaving packets, padding the resulting stream with NULL packets if
> necessary and then delivering the resulting TS packets to the bridge
> driver so it can feed the demux.
> 
> This patch includes a "channel" abstraction, which attempts to map a
> MPEG service into a struct that vidtv can work with.
> 
> When vidtv boots, it will create some hardcoded channels:
> 
> -Their services will be concatenated to populate the SDT.
> -Their programs will be concatenated to populate the PAT
> -For each program in the PAT, a PMT section will be created
> -The PMT section for a channel will be assigned its streams.
> -Every stream will have its corresponding encoder polled to produce TS packets
> -These packets may be interleaved by the mux and then delivered to the bridg
> 
> Signed-off-by: Daniel W. S. Almeida <dwlsalmeida@gmail.com>

The same notes I made on previous patches apply here.

> ---
>  drivers/media/test-drivers/vidtv/Makefile     |   2 +-
>  .../media/test-drivers/vidtv/vidtv_bridge.c   |  67 ++-
>  .../media/test-drivers/vidtv/vidtv_bridge.h   |   2 +
>  .../media/test-drivers/vidtv/vidtv_channel.c  | 326 ++++++++++++++
>  .../media/test-drivers/vidtv/vidtv_channel.h  |  66 +++
>  .../media/test-drivers/vidtv/vidtv_common.h   |   3 +
>  drivers/media/test-drivers/vidtv/vidtv_mux.c  | 423 ++++++++++++++++++
>  drivers/media/test-drivers/vidtv/vidtv_mux.h  | 105 +++++
>  drivers/media/test-drivers/vidtv/vidtv_psi.c  |  18 +
>  drivers/media/test-drivers/vidtv/vidtv_psi.h  |   5 +
>  10 files changed, 1014 insertions(+), 3 deletions(-)
>  create mode 100644 drivers/media/test-drivers/vidtv/vidtv_channel.c
>  create mode 100644 drivers/media/test-drivers/vidtv/vidtv_channel.h
>  create mode 100644 drivers/media/test-drivers/vidtv/vidtv_mux.c
>  create mode 100644 drivers/media/test-drivers/vidtv/vidtv_mux.h
> 
> diff --git a/drivers/media/test-drivers/vidtv/Makefile b/drivers/media/test-drivers/vidtv/Makefile
> index c916eb19d73bb..a1d29001fffe3 100644
> --- a/drivers/media/test-drivers/vidtv/Makefile
> +++ b/drivers/media/test-drivers/vidtv/Makefile
> @@ -2,6 +2,6 @@
>  
>  vidtv_demod-objs := vidtv_common.o
>  vidtv_bridge-objs := vidtv_common.o vidtv_ts.o vidtv_psi.o vidtv_pes.o \
> -		     vidtv_s302m.o
> +		     vidtv_s302m.o vidtv_channel.o vidtv_mux.o
>  
>  obj-$(CONFIG_DVB_VIDTV)	+= vidtv_tuner.o vidtv_demod.o vidtv_bridge.o
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_bridge.c b/drivers/media/test-drivers/vidtv/vidtv_bridge.c
> index 05ca4027c869f..c9876372fdebd 100644
> --- a/drivers/media/test-drivers/vidtv/vidtv_bridge.c
> +++ b/drivers/media/test-drivers/vidtv/vidtv_bridge.c
> @@ -13,8 +13,10 @@
>  #include <linux/workqueue.h>
>  #include <linux/time.h>
>  #include "vidtv_bridge.h"
> +#include "vidtv_ts.h"
> +#include "vidtv_mux.h"
>  
> -#define TS_BUF_MAX_SZ (128 * 188)
> +#define TS_BUF_MAX_SZ (128 * TS_PACKET_LEN)
>  #define TUNER_DEFAULT_ADDR 0x68
>  #define DEMOD_DEFAULT_ADDR 0x60
>  
> @@ -64,16 +66,63 @@ module_param(chosen_delsys, uint, 0644);
>  MODULE_PARM_DESC(chosen_delsys,
>  		 "The delivery system to simulate. Currently supported: DVB-T, DVB-C, DVB-S");
>  
> -static unsigned int ts_buf_sz = 20 * 188;
> +static unsigned int ts_buf_sz = 20 * TS_PACKET_LEN;
>  module_param(ts_buf_sz, uint, 0644);
>  MODULE_PARM_DESC(ts_buf_sz, "Optional size for the TS buffer");
>  
>  DVB_DEFINE_MOD_OPT_ADAPTER_NR(adapter_nums);
>  
> +/*
> + * Influences the signal acquisition time. See ISO/IEC 13818-1 : 2000. p. 113.
> + */
> +static unsigned int si_period_msec = 40;
> +module_param(si_period_msec, uint, 0644);
> +MODULE_PARM_DESC(si_period_msec, "How often to send SI packets. Default: 40ms");
> +
> +static unsigned int pcr_period_msec = 40;
> +module_param(pcr_period_msec, uint, 0644);
> +MODULE_PARM_DESC(pcr_period_msec, "How often to send PCR packets. Default: 40ms");
> +
> +static unsigned int mux_rate_kbytes_sec = 4096;
> +module_param(mux_rate_kbytes_sec, uint, 0644);
> +MODULE_PARM_DESC(mux_rate_kbytes_sec, "Optional mux rate: will pad stream if below");
> +
> +static unsigned int pcr_pid = 0x200
> +module_param(pcr_pid, uint, 0644);
> +MODULE_PARM_DESC(pcr_pid, "Optional PCR PID for all channels: defaults to 0x200");
> +

Same comments I made on a past patch about module parameters apply here.

Also, for the last two, I would remove the "Optional" word. All modprobe
parameters are optional ;-)

> +static bool vidtv_bridge_check_demod_lock(struct vidtv_dvb *dvb, u32 n)
> +{
> +	enum fe_status status;
> +
> +	dvb->fe[n]->ops.read_status(dvb->fe[n], &status);
> +
> +	return status == FE_HAS_SIGNAL  |
> +			 FE_HAS_CARRIER |
> +			 FE_HAS_VITERBI |
> +			 FE_HAS_SYNC    |
> +			 FE_HAS_LOCK;
> +}
> +
> +static void
> +vidtv_bridge_on_new_pkts_avail(void *priv, u8 *buf, u32 npkts)
> +{
> +	/*
> +	 * called on a separate thread by the mux when new packets become
> +	 * available
> +	 */
> +	struct vidtv_dvb *dvb = (struct vidtv_dvb *)priv;
> +
> +	/* drop packets if we lose the lock */
> +	if (vidtv_bridge_check_demod_lock(dvb, 0))
> +		dvb_dmx_swfilter_packets(&dvb->demux, buf, npkts);
> +}
> +
>  static int vidtv_start_streaming(struct vidtv_dvb *dvb)
>  {
>  	WARN_ON(dvb->streaming);
>  	dvb->streaming = true;
> +	vidtv_mux_start_thread(dvb->mux);
>  
>  	return 0;
>  }
> @@ -82,6 +131,7 @@ static int vidtv_stop_streaming(struct vidtv_dvb *dvb)
>  {
>  	/* mpeg thread will quit */
>  	dvb->streaming = false;
> +	vidtv_mux_stop_thread(dvb->mux);
>  
>  	return 0;
>  }
> @@ -313,6 +363,7 @@ static int vidtv_bridge_i2c_probe(struct i2c_client *client,
>  {
>  	int ret;
>  	struct vidtv_dvb *dvb;
> +	struct vidtv_mux_init_args mux_args = {0};
>  
>  	dvb = kzalloc(sizeof(*dvb), GFP_KERNEL);
>  	if (!dvb)
> @@ -324,6 +375,16 @@ static int vidtv_bridge_i2c_probe(struct i2c_client *client,
>  
>  	mutex_init(&dvb->feed_lock);
>  
> +	mux_args.mux_rate_kbytes_sec = mux_rate_kbytes_sec;
> +	mux_args.on_new_packets_available_cb = vidtv_bridge_on_new_pkts_avail;
> +	mux_args.ts_buf_sz = ts_buf_sz;
> +	mux_args.pcr_period_usecs = pcr_period_msecs * 1000;
> +	mux_args.si_period_usecs = si_period_msecs * 1000;
> +	mux_args.pcr_pid = pcr_pid;
> +	mux_args.priv = dvb;
> +
> +	dvb->mux = vidtv_mux_init(mux_args);
> +
>  	i2c_set_clientdata(client, dvb);
>  
>  	return ret;
> @@ -340,6 +401,8 @@ static int vidtv_bridge_i2c_remove(struct i2c_client *client)
>  
>  	dvb = i2c_get_clientdata(client);
>  
> +	vidtv_mux_destroy(dvb->mux);
> +
>  	mutex_destroy(&dvb->feed_lock);
>  
>  	for (i = 0; i < NUM_FE; ++i)
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_bridge.h b/drivers/media/test-drivers/vidtv/vidtv_bridge.h
> index ef5c7cd2d64e3..f5e6931058c9c 100644
> --- a/drivers/media/test-drivers/vidtv/vidtv_bridge.h
> +++ b/drivers/media/test-drivers/vidtv/vidtv_bridge.h
> @@ -17,6 +17,7 @@
>  #include <media/dvb_demux.h>
>  #include <media/dmxdev.h>
>  #include <linux/i2c.h>
> +#include "vidtv_mux.h"
>  
>  struct vidtv_dvb {
>  	struct dvb_frontend *fe[NUM_FE];
> @@ -32,6 +33,7 @@ struct vidtv_dvb {
>  	struct mutex feed_lock; /* start/stop feed */
>  
>  	bool streaming;
> +	struct vidtv_mux *mux;
>  };
>  
>  #endif // VIDTV_BRIDGE_H
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_channel.c b/drivers/media/test-drivers/vidtv/vidtv_channel.c
> new file mode 100644
> index 0000000000000..3e89a40eb7ca6
> --- /dev/null
> +++ b/drivers/media/test-drivers/vidtv/vidtv_channel.c
> @@ -0,0 +1,326 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Vidtv 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.
> + *
> + * This file contains the code for a 'channel' abstraction.
> + *
> + * When vidtv boots, it will create some hardcoded channels.
> + * Their services will be concatenated to populate the SDT.
> + * Their programs will be concatenated to populate the PAT
> + * For each program in the PAT, a PMT section will be created
> + * The PMT section for a channel will be assigned its streams.
> + * Every stream will have its corresponding encoder polled to produce TS packets
> + * These packets may be interleaved by the mux and then delivered to the bridge
> + *
> + *
> + * Written by Daniel W. S. Almeida <dwlsalmeida@gmail.com>
> + */
> +
> +#include <linux/types.h>
> +#include <linux/slab.h>
> +#include "vidtv_channel.h"
> +#include "vidtv_psi.h"
> +#include "vidtv_encoder.h"
> +#include "vidtv_mux.h"
> +#include "vidtv_common.h"
> +#include "vidtv_s302m.h"
> +
> +static void vidtv_channel_encoder_destroy(struct vidtv_encoder *e)
> +{
> +	struct vidtv_encoder *curr = e;
> +
> +	while (curr) {
> +		/* forward the call to the derived type */
> +		curr->destroy(curr);
> +		curr = curr->next;
> +	}
> +}
> +
> +static struct vidtv_channel
> +*vidtv_channel_s302m_init(struct vidtv_channel *head)
> +{
> +	/* init an audio only channel with a s302m encoder */
> +	const u16 s302m_service_id          = 0x880;
> +	const u16 s302m_program_num         = 0x880;
> +	const u16 s302m_program_pid         = 0x101; /* packet id for PMT*/
> +	const u16 s302m_es_pid              = 0x111; /* packet id for the ES */
> +	const u16 s302m_pes_audio_stream_id = 0xbd;  /* PES: private_stream_1 */
> +
> +	struct vidtv_channel *s302m = kzalloc(sizeof(*s302m), GFP_KERNEL);
> +	struct vidtv_psi_table_sdt_service *s302m_service;
> +	struct vidtv_psi_desc_service *s302m_s_desc;
> +	struct vidtv_s302m_encoder_init_args encoder_args = {0};
> +
> +	s302m_service = vidtv_psi_sdt_service_init(NULL, s302m_service_id);
> +
> +	s302m_s_desc = (struct vidtv_psi_desc_service *)
> +		       vidtv_psi_desc_init(NULL,
> +					   SERVICE_DESCRIPTOR,
> +					   sizeof(*s302m_s_desc));
> +
> +	s302m_s_desc->name         = "Sine Wave PCM Audio";
> +	s302m_s_desc->service_type = DIGITAL_TELEVISION_SERVICE;
> +
> +	s302m_s_desc->length = sizeof(s302m_s_desc->service_type)
> +			       + strlen(s302m_s_desc->name)
> +			       + strlen(s302m_s_desc->name_emph)
> +			       + strlen(s302m_s_desc->provider)
> +			       + strlen(s302m_s_desc->provider_emph);
> +
> +	vidtv_psi_desc_assign(&s302m_service->descriptor,
> +			      (struct vidtv_psi_desc *)
> +			      s302m_s_desc);
> +
> +	s302m->transport_stream_id = TRANSPORT_STREAM_ID;
> +
> +	s302m->program = vidtv_psi_pat_program_init(NULL,
> +						    s302m_service_id,
> +						    s302m_program_pid);
> +
> +	s302m->program_num = s302m_program_num;
> +
> +	s302m->streams = vidtv_psi_pmt_stream_init(NULL,
> +						   STREAM_PRIVATE_DATA,
> +						   s302m_pes_audio_stream_id);
> +
> +	encoder_args.access_unit_capacity = 16;
> +	encoder_args.es_pid               = s302m_es_pid;
> +
> +	s302m->encoders = vidtv_s302m_encoder_init(encoder_args);
> +
> +	if (head) {
> +		while (head->next)
> +			head = head->next;
> +
> +		head->next = s302m;
> +	}
> +
> +	return s302m;
> +}
> +
> +static struct vidtv_psi_table_sdt_service
> +*vidtv_channel_sdt_serv_cat_into_new(struct vidtv_channel *channels)
> +{
> +	struct vidtv_channel *cur_chnl           = channels;
> +	struct vidtv_psi_table_sdt_service *curr = NULL;
> +	struct vidtv_psi_table_sdt_service *head = NULL;
> +	struct vidtv_psi_table_sdt_service *tail = NULL;
> +	u16 service_id;
> +
> +	while (cur_chnl) {
> +		curr       = cur_chnl->service;
> +		service_id = curr->service_id;
> +
> +		if (!curr)
> +			continue;
> +
> +		while (curr->next) {
> +			tail = vidtv_psi_sdt_service_init(tail, service_id);
> +
> +			if (!head)
> +				head = tail;
> +
> +			curr = curr->next;
> +		}
> +
> +		cur_chnl = cur_chnl->next;
> +	}
> +
> +	return head;
> +}
> +
> +static struct vidtv_psi_table_pat_program*
> +vidtv_channel_pat_prog_cat_into_new(struct vidtv_channel *channels)
> +{
> +	struct vidtv_channel *cur_chnl           = channels;
> +	struct vidtv_psi_table_pat_program *curr = NULL;
> +	struct vidtv_psi_table_pat_program *head = NULL;
> +	struct vidtv_psi_table_pat_program *tail = NULL;
> +
> +	while (cur_chnl) {
> +		curr = cur_chnl->program;
> +
> +		if (!curr)
> +			continue;
> +
> +		while (curr->next) {
> +			tail = vidtv_psi_pat_program_init(tail,
> +							  curr->service_id,
> +							  curr->pid);
> +
> +			if (!head)
> +				head = tail;
> +
> +			curr = curr->next;
> +		}
> +
> +		cur_chnl = cur_chnl->next;
> +	}
> +
> +	return head;
> +}
> +
> +static void
> +vidtv_channel_pmt_match_sections(struct vidtv_channel *channels,
> +				 struct vidtv_psi_table_pmt sections[],
> +				 u32 nsections)
> +{
> +	struct vidtv_psi_table_pmt *curr_section = NULL;
> +	struct vidtv_channel *cur_chnl           = channels;
> +	u32 j;
> +
> +	while (cur_chnl) {
> +		for (j = 0; j < nsections; ++j) {
> +			curr_section = &sections[j];
> +
> +			if (!curr_section)
> +				continue;
> +
> +			/* we got a match */
> +			if (curr_section->header.id == cur_chnl->program_num) {
> +				vidtv_psi_pmt_stream_assign(curr_section,
> +							    cur_chnl->streams);
> +				break;
> +			}
> +		}
> +
> +		cur_chnl = cur_chnl->next;
> +	}
> +}
> +
> +void vidtv_channel_si_init(struct vidtv_mux *m)
> +{
> +	struct vidtv_psi_table_pat *pat = m->si.pat;
> +	struct vidtv_psi_table_sdt *sdt = m->si.sdt;
> +
> +	struct vidtv_psi_table_pmt *pmt_sections = m->si.pmt_secs;
> +
> +	struct vidtv_psi_table_pat_program *programs = NULL;
> +	struct vidtv_psi_table_sdt_service *services = NULL;
> +
> +	bool update_version_num = false;
> +
> +	vidtv_psi_pat_table_init(pat,
> +				 update_version_num,
> +				 TRANSPORT_STREAM_ID);
> +
> +	vidtv_psi_sdt_table_init(sdt,
> +				 update_version_num,
> +				 TRANSPORT_STREAM_ID);
> +
> +	programs = vidtv_channel_pat_prog_cat_into_new(m->channels);
> +	services = vidtv_channel_sdt_serv_cat_into_new(m->channels);
> +
> +	/* assemble all programs and assign to PAT */
> +	vidtv_psi_pat_program_assign(pat, programs);
> +
> +	/* assemble all services and assign to SDT */
> +	vidtv_psi_sdt_service_assign(sdt, services);
> +
> +	/* a section for each program_id */
> +	pmt_sections = kcalloc(pat->programs,
> +			       sizeof(struct vidtv_psi_table_pmt),
> +			       GFP_KERNEL);
> +
> +	vidtv_psi_pmt_create_sec_for_each_pat_entry(pat,
> +						    pmt_sections);
> +
> +	vidtv_channel_pmt_match_sections(m->channels,
> +					 pmt_sections,
> +					 pat->programs);
> +}
> +
> +void vidtv_channel_si_destroy(struct vidtv_mux *m)
> +{
> +	u32 i;
> +
> +	vidtv_psi_pat_table_destroy(m->si.pat);
> +
> +	for (i = 0; i < m->si.num_pmt_sections; ++i)
> +		vidtv_psi_pmt_table_destroy(&m->si.pmt_secs[i]);
> +
> +	kfree(m->si.pmt_secs);
> +	vidtv_psi_sdt_table_destroy(m->si.sdt);
> +}
> +
> +void vidtv_channels_init(struct vidtv_mux *m)
> +{
> +	/* we only have a single channel for now */
> +	m->channels = vidtv_channel_s302m_init(NULL);
> +}
> +
> +void vidtv_channels_destroy(struct vidtv_mux *m)
> +{
> +	struct vidtv_channel *curr = m->channels;
> +
> +	while (curr) {
> +		vidtv_psi_sdt_service_destroy(curr->service);
> +		vidtv_psi_pat_program_destroy(curr->program);
> +		vidtv_psi_pmt_stream_destroy(curr->streams);
> +		vidtv_channel_encoder_destroy(curr->encoders);
> +		curr = curr->next;
> +	}
> +}
> +
> +static void
> +vidtv_channels_add_registration_s302m(struct vidtv_psi_table_pmt *sec)
> +{
> +	struct vidtv_psi_desc_registration *s302m_r_desc;
> +
> +	/* there might be some descriptors there already */
> +	struct vidtv_psi_desc *parent = sec->descriptor;
> +
> +	s302m_r_desc = (struct vidtv_psi_desc_registration *)
> +			vidtv_psi_desc_init(parent,
> +					    REGISTRATION_DESCRIPTOR,
> +					    sizeof(*s302m_r_desc));
> +
> +	s302m_r_desc->format_identifier = VIDTV_S302M_FORMAT_IDENTIFIER;
> +
> +	if (!parent)
> +		vidtv_psi_desc_assign(&sec->descriptor,
> +				      (struct vidtv_psi_desc *)s302m_r_desc);
> +
> +	/* we are adding to the table, so recompute the length */
> +	vidtv_psi_pmt_table_comp_sec_len(sec);
> +}
> +
> +void vidtv_channels_add_registration_descs(struct vidtv_mux *m)
> +{
> +	/*
> +	 * Some formats might need a registration descriptor to be recognized.
> +	 * S302M needs it, and ffmpeg actually checks for it, so add such
> +	 * descriptor at the PMT section that contains the stream
> +	 */
> +	struct vidtv_channel *cur_chnl  = m->channels;
> +	struct vidtv_encoder *e         = NULL;
> +	struct vidtv_psi_table_pmt *sec = NULL;
> +
> +	while (cur_chnl) {
> +		e   = cur_chnl->encoders;
> +		sec = vidtv_psi_find_pmt_sec(m->si.pmt_secs,
> +					     m->si.pat->programs,
> +					     cur_chnl->program_num);
> +
> +		/* bug somewhere */
> +		WARN_ON(!sec);
> +		if (!sec)
> +			continue;
> +
> +		while (e) {
> +			switch (e->id) {
> +			case S302M:
> +				vidtv_channels_add_registration_s302m(sec);
> +				break;
> +			default:
> +				break;
> +			}
> +
> +			e = e->next;
> +		}
> +
> +		cur_chnl = cur_chnl->next;
> +	}
> +}
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_channel.h b/drivers/media/test-drivers/vidtv/vidtv_channel.h
> new file mode 100644
> index 0000000000000..02141c4c732f0
> --- /dev/null
> +++ b/drivers/media/test-drivers/vidtv/vidtv_channel.h
> @@ -0,0 +1,66 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Vidtv 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.
> + *
> + * This file contains the code for a 'channel' abstraction.
> + *
> + * When vidtv boots, it will create some hardcoded channels.
> + * Their services will be concatenated to populate the SDT.
> + * Their programs will be concatenated to populate the PAT
> + * For each program in the PAT, a PMT section will be created
> + * The PMT section for a channel will be assigned its streams.
> + * Every stream will have its corresponding encoder polled to produce TS packets
> + * These packets may be interleaved by the mux and then delivered to the bridge
> + *
> + *
> + * Written by Daniel W. S. Almeida <dwlsalmeida@gmail.com>
> + */
> +
> +#ifndef VIDTV_CHANNEL_H
> +#define VIDTV_CHANNEL_H
> +
> +#include <linux/types.h>
> +#include "vidtv_psi.h"
> +#include "vidtv_encoder.h"
> +#include "vidtv_mux.h"
> +
> +struct vidtv_channel {
> +	/* a number to identify the TS, chosen at will */
> +	u16 transport_stream_id;
> +
> +	/* will be concatenated into the SDT */
> +	struct vidtv_psi_table_sdt_service *service;
> +
> +	/* the link between SDT, PAT and PMT */
> +	u16 program_num;
> +
> +	/*
> +	 * a single program with one or more streams associated with it.
> +	 * Will be concatenated into the PAT
> +	 */
> +	struct vidtv_psi_table_pat_program *program;
> +
> +	/*
> +	 * one or more streams associated with the program
> +	 * Will populate the PMT section for this program
> +	 */
> +	struct vidtv_psi_table_pmt_stream *streams;
> +
> +	/* a list of encoders, one for each stream */
> +	struct vidtv_encoder *encoders;
> +
> +	struct vidtv_channel *next;
> +};
> +
> +/* init SI data from the channels */
> +void vidtv_channel_si_init(struct vidtv_mux *m);
> +void vidtv_channel_si_destroy(struct vidtv_mux *m);
> +
> +void vidtv_channels_init(struct vidtv_mux *m);
> +void vidtv_channels_destroy(struct vidtv_mux *m);
> +
> +void vidtv_channels_add_registration_descs(struct vidtv_mux *m);
> +
> +#endif //VIDTV_CHANNEL_H
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_common.h b/drivers/media/test-drivers/vidtv/vidtv_common.h
> index 170646497eb58..64c85503d4113 100644
> --- a/drivers/media/test-drivers/vidtv/vidtv_common.h
> +++ b/drivers/media/test-drivers/vidtv/vidtv_common.h
> @@ -14,6 +14,9 @@
>  #include <media/dvb_frontend.h>
>  
>  #define CLOCK_UNIT_90KHZ 90000
> +#define CLOCK_UNIT_27MHZ 27000000
> +#define SLEEP_USECS 10000
> +#define TRANSPORT_STREAM_ID 0x744
>  
>  u32 vidtv_memcpy(void *to,
>  		 const void *from,
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_mux.c b/drivers/media/test-drivers/vidtv/vidtv_mux.c
> new file mode 100644
> index 0000000000000..6d553be27622f
> --- /dev/null
> +++ b/drivers/media/test-drivers/vidtv/vidtv_mux.c
> @@ -0,0 +1,423 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Vidtv 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.
> + *
> + * This file contains the multiplexer logic for TS packets from different
> + * elementary streams
> + *
> + * Written by Daniel W. S. Almeida <dwlsalmeida@gmail.com>
> + */
> +
> +#include <linux/types.h>
> +#include <linux/slab.h>
> +#include <linux/jiffies.h>
> +#include <linux/kernel.h>
> +#include "vidtv_mux.h"
> +#include "vidtv_ts.h"
> +#include "vidtv_pes.h"
> +#include "vidtv_encoder.h"
> +#include "vidtv_channel.h"
> +#include "vidtv_common.h"
> +#include "vidtv_psi.h"
> +
> +static struct vidtv_mux_pid_ctx
> +*vidtv_mux_get_pid_ctx(struct vidtv_mux *m, u16 pid)
> +{
> +	struct vidtv_mux_pid_ctx *ctx;
> +
> +	hash_for_each_possible(m->pid_ctx, ctx, h, pid)
> +		if (ctx->pid == pid)
> +			return ctx;
> +
> +	return NULL;
> +}
> +
> +static struct vidtv_mux_pid_ctx
> +*vidtv_mux_create_pid_ctx_once(struct vidtv_mux *m, u16 pid)
> +{
> +	struct vidtv_mux_pid_ctx *ctx;
> +
> +	ctx = vidtv_mux_get_pid_ctx(m, pid);
> +
> +	if (ctx)
> +		goto end;
> +
> +	ctx      = kzalloc(sizeof(*ctx), GFP_KERNEL);
> +	ctx->pid = pid;
> +	ctx->cc  = 0;
> +	hash_add(m->pid_ctx, &ctx->h, pid);
> +
> +end:
> +	return ctx;
> +}
> +
> +static void vidtv_mux_pid_ctx_init(struct vidtv_mux *m)
> +{
> +	struct vidtv_psi_table_pat_program *p = m->si.pat->program;
> +
> +	hash_init(m->pid_ctx);
> +	/* push the pcr pid ctx */
> +	vidtv_mux_create_pid_ctx_once(m, m->pcr_pid);
> +	/* push the null packet pid ctx */
> +	vidtv_mux_create_pid_ctx_once(m, TS_NULL_PACKET_PID);
> +	/* push the PAT pid ctx */
> +	vidtv_mux_create_pid_ctx_once(m, VIDTV_PAT_PID);
> +	/* push the SDT pid ctx */
> +	vidtv_mux_create_pid_ctx_once(m, VIDTV_SDT_PID);
> +
> +	/* add a ctx for all PMT sections */
> +	while (p) {
> +		vidtv_mux_create_pid_ctx_once(m, p->pid);
> +		p = p->next;
> +	}
> +}
> +
> +static void vidtv_mux_pid_ctx_destroy(struct vidtv_mux *m)
> +{
> +	int bkt;
> +	struct vidtv_mux_pid_ctx *ctx;
> +
> +	hash_for_each(m->pid_ctx, bkt, ctx, h) {
> +		kfree(ctx);
> +	}
> +}
> +
> +static void vidtv_mux_update_clk(struct vidtv_mux *m)
> +{
> +	/* call this at every thread iteration */
> +	u64 elapsed_time;
> +
> +	/* this will not hold a value yet if we have just started */
> +	m->timing.past_jiffies = m->timing.current_jiffies ?
> +				 m->timing.current_jiffies :
> +				 get_jiffies_64();
> +
> +	m->timing.current_jiffies = get_jiffies_64();
> +
> +	elapsed_time = jiffies_to_usecs(m->timing.current_jiffies -
> +					m->timing.past_jiffies);
> +
> +	/* update the 27Mhz clock proportionally to the elapsed time */
> +	m->timing.clk += (CLOCK_UNIT_27MHZ / USEC_PER_SEC) * elapsed_time;
> +}
> +
> +static u32 vidtv_mux_push_si(struct vidtv_mux *m)
> +{
> +	u32 initial_offset = m->ts_buf_offset;
> +	struct vidtv_mux_pid_ctx *pat_ctx, *pmt_ctx, *sdt_ctx;
> +	u32 nbytes; /* the number of bytes written by this function */
> +	u16 pmt_pid;
> +	u32 i;
> +
> +	pat_ctx = vidtv_mux_get_pid_ctx(m, VIDTV_PAT_PID);
> +	sdt_ctx = vidtv_mux_get_pid_ctx(m, VIDTV_SDT_PID);
> +
> +	m->ts_buf_offset += vidtv_psi_pat_write_into(m->ts_buf,
> +						     m->ts_buf_offset,
> +						     m->si.pat,
> +						     m->ts_buf_sz,
> +						     &pat_ctx->cc);
> +
> +	for (i = 0; i < m->si.num_pmt_sections; ++i) {
> +		pmt_pid = vidtv_psi_pmt_get_pid(&m->si.pmt_secs[i],
> +						m->si.pat);
> +
> +		/* not found */
> +		WARN_ON(pmt_pid > TS_LAST_VALID_PID);
> +		if (pmt_pid > TS_LAST_VALID_PID)
> +			continue;
> +
> +		pmt_ctx = vidtv_mux_get_pid_ctx(m, pmt_pid);
> +
> +		/* write each section into buffer */
> +		m->ts_buf_offset += vidtv_psi_pmt_write_into(m->ts_buf,
> +							     m->ts_buf_offset,
> +							     &m->si.pmt_secs[i],
> +							     pmt_pid,
> +							     m->ts_buf_sz,
> +							     &pmt_ctx->cc);
> +	}
> +
> +	m->ts_buf_offset += vidtv_psi_sdt_write_into(m->ts_buf,
> +						     m->ts_buf_offset,
> +						     m->si.sdt,
> +						     m->ts_buf_sz,
> +						     &sdt_ctx->cc);
> +
> +	nbytes = m->ts_buf_offset - initial_offset;
> +	return nbytes;
> +}
> +
> +static u32 vidtv_mux_push_pcr(struct vidtv_mux *m)
> +{
> +	struct pcr_write_args args = {0};
> +	struct vidtv_mux_pid_ctx *ctx;
> +
> +	ctx                     = vidtv_mux_get_pid_ctx(m, m->pcr_pid);
> +	args.dest_buf           = m->ts_buf;
> +	args.pid                = m->pcr_pid;
> +	args.buf_sz             = m->ts_buf_sz;
> +	args.continuity_counter = &ctx->cc;
> +
> +	/* the 27Mhz clock will feed both parts of the PCR bitfield */
> +	args.pcr = m->timing.clk;
> +
> +	return vidtv_ts_pcr_write_into(args);
> +}
> +
> +static bool vidtv_mux_should_push_pcr(struct vidtv_mux *m)
> +{
> +	u64 next_pcr_at;
> +
> +	next_pcr_at = m->timing.start_jiffies +
> +		      usecs_to_jiffies(m->num_streamed_pcr *
> +				       m->timing.pcr_period_usecs);
> +
> +	return time_after64(m->timing.current_jiffies, next_pcr_at);
> +}
> +
> +static bool vidtv_mux_should_push_si(struct vidtv_mux *m)
> +{
> +	u64 next_si_at;
> +
> +	next_si_at = m->timing.start_jiffies +
> +		     usecs_to_jiffies(m->num_streamed_si *
> +				      m->timing.si_period_usecs);
> +
> +	return time_after64(m->timing.current_jiffies, next_si_at);
> +}
> +
> +static u32 vidtv_mux_packetize_access_units(struct vidtv_mux *m,
> +					    struct vidtv_encoder *e)
> +{
> +	/* the number of bytes written by this function */
> +	u32    nbytes              = 0;
> +	struct pes_write_args args = {0};
> +	u32    initial_offset      = m->ts_buf_offset;
> +
> +	u32 i;
> +	u8 *buf;
> +	struct vidtv_mux_pid_ctx *pid_ctx;
> +
> +	pid_ctx = vidtv_mux_create_pid_ctx_once(m, e->es_pid);
> +
> +	args.dest_buf           = m->ts_buf;
> +	args.dest_buf_sz        = m->ts_buf_sz;
> +	args.pid                = e->es_pid;
> +	args.is_s302m_pkt       = (e->id == S302M);
> +	args.continuity_counter = &pid_ctx->cc;
> +	args.send_pts           = true;
> +
> +	for (i = 0; i < e->nunits; ++i) {
> +		buf                  = e->encoder_buf + e->offsets[i];
> +		args.from            = buf;
> +		args.access_unit_len = e->nbytes[i];
> +		args.dest_offset     = m->ts_buf_offset;
> +		args.pts             = e->pts[i];
> +
> +		m->ts_buf_offset += vidtv_pes_write_into(args);
> +	}
> +
> +	/* clear the encoder state once we have written the current ES data */
> +	e->clear(e);
> +
> +	nbytes = m->ts_buf_offset - initial_offset;
> +	return nbytes;
> +}
> +
> +static u32 vidtv_mux_poll_encoders(struct vidtv_mux *m)
> +{
> +	u32    nbytes                  = 0;
> +	struct vidtv_channel *cur_chnl = m->channels;
> +	struct vidtv_encoder *e        = NULL;
> +
> +	u64    elapsed_time_usecs = jiffies_to_usecs(m->timing.current_jiffies -
> +						     m->timing.past_jiffies);
> +	while (cur_chnl) {
> +		e = cur_chnl->encoders;
> +
> +		while (e) {
> +			/* encode for 'elapsed_time_usecs' */
> +			e->encode(e, elapsed_time_usecs);
> +			/* get the TS packets into the mux buffer */
> +			nbytes += vidtv_mux_packetize_access_units(m, e);
> +			/* grab next encoder */
> +			e = e->next;
> +		}
> +
> +		/* grab the next channel */
> +		cur_chnl = cur_chnl->next;
> +	}
> +
> +	return nbytes;
> +}
> +
> +static u32 vidtv_mux_pad_with_nulls(struct vidtv_mux *m, u32 npkts)
> +{
> +	struct null_packet_write_args args = {0};
> +	u32    initial_offset              = m->ts_buf_offset;
> +	u32 nbytes; /* the number of bytes written by this function */
> +	u32 i;
> +	struct vidtv_mux_pid_ctx *ctx;
> +
> +	ctx = vidtv_mux_get_pid_ctx(m, TS_NULL_PACKET_PID);
> +
> +	args.dest_buf           = m->ts_buf;
> +	args.buf_sz             = m->ts_buf_sz;
> +	args.continuity_counter = &ctx->cc;
> +	args.dest_offset        = m->ts_buf_offset;
> +
> +	for (i = 0; i < npkts; ++i) {
> +		m->ts_buf_offset += vidtv_ts_null_write_into(args);
> +		args.dest_offset  = m->ts_buf_offset;
> +	}
> +
> +	nbytes = m->ts_buf_offset - initial_offset;
> +
> +	/* sanity check */
> +	WARN_ON(nbytes != npkts * TS_PACKET_LEN);
> +
> +	return nbytes;
> +}
> +
> +static u32 vidtv_mux_check_mux_rate(struct vidtv_mux *m)
> +{
> +	/*
> +	 * attempt to maintain a constant mux rate, padding with null packets
> +	 * if needed
> +	 */
> +
> +	u32 nbytes = 0;  /* the number of bytes written by this function */
> +
> +	u64 nbytes_expected; /* the number of bytes we should have written */
> +	u64 nbytes_streamed; /* the number of bytes we actually wrote */
> +	u32 num_null_pkts; /* number of null packets to bridge the gap */
> +
> +	u64 elapsed_time_usecs = jiffies_to_usecs(m->timing.current_jiffies -
> +						  m->timing.past_jiffies);
> +
> +	nbytes_expected  = (m->mux_rate_kbytes_sec / 1000) / USEC_PER_SEC;
> +	nbytes_expected *= elapsed_time_usecs;
> +
> +	nbytes_streamed = m->num_streamed_pkts * TS_PACKET_LEN;
> +
> +	if (nbytes_streamed < nbytes_expected) {
> +		/* can't write half a packet: roundup to a 188 multiple */
> +		nbytes_expected  = roundup(nbytes_expected, TS_PACKET_LEN);
> +		num_null_pkts    = nbytes_expected / TS_PACKET_LEN;
> +		nbytes          += vidtv_mux_pad_with_nulls(m, num_null_pkts);
> +	}
> +
> +	return nbytes;
> +}
> +
> +static void vidtv_mux_clear(struct vidtv_mux *m)
> +{
> +	/* clear the packets currently in the mux */
> +	memset(m->ts_buf, 0, m->ts_buf_sz);
> +	/* point to the beginning of the buffer again */
> +	m->ts_buf_offset = 0;
> +}
> +
> +static void vidtv_mux_tick(struct work_struct *work)
> +{
> +	struct vidtv_mux *m = container_of(work,
> +					   struct vidtv_mux,
> +					   mpeg_thread);
> +	u32 nbytes;
> +	u32 npkts;
> +
> +	while (m->streaming) {
> +		nbytes = 0;
> +
> +		vidtv_mux_update_clk(m);
> +
> +		if (vidtv_mux_should_push_pcr(m))
> +			nbytes += vidtv_mux_push_pcr(m);
> +
> +		if (vidtv_mux_should_push_si(m))
> +			nbytes += vidtv_mux_push_si(m);
> +
> +		nbytes += vidtv_mux_poll_encoders(m);
> +
> +		nbytes += vidtv_mux_check_mux_rate(m);
> +
> +		npkts = nbytes / TS_PACKET_LEN;
> +		/* if the buffer is not aligned there is a bug somewhere */
> +		WARN_ON(nbytes % TS_PACKET_LEN);
> +
> +		if (m->on_new_packets_available_cb)
> +			m->on_new_packets_available_cb(m->priv,
> +						       m->ts_buf,
> +						       npkts);
> +
> +		m->num_streamed_pkts += npkts;
> +		vidtv_mux_clear(m);
> +
> +		usleep_range(SLEEP_USECS, 2 * SLEEP_USECS);
> +	}
> +}
> +
> +void vidtv_mux_start_thread(struct vidtv_mux *m)
> +{
> +	WARN_ON(m->streaming);
> +
> +	if (m->streaming)
> +		return;
> +
> +	m->streaming            = true;
> +	m->timing.start_jiffies = get_jiffies_64();
> +	schedule_work(&m->mpeg_thread);
> +}
> +
> +void vidtv_mux_stop_thread(struct vidtv_mux *m)
> +{
> +	/* thread will quit */
> +	m->streaming = false;
> +}
> +
> +struct vidtv_mux *vidtv_mux_init(struct vidtv_mux_init_args args)
> +{
> +	struct vidtv_mux *m = kzalloc(sizeof(*m), GFP_KERNEL);
> +
> +	m->timing.pcr_period_usecs = args.pcr_period_usecs;
> +	m->timing.si_period_usecs  = args.si_period_usecs;
> +
> +	m->mux_rate_kbytes_sec = args.mux_rate_kbytes_sec;
> +
> +	m->on_new_packets_available_cb = args.on_new_packets_available_cb;
> +
> +	m->ts_buf    = vmalloc(args.ts_buf_sz);
> +	m->ts_buf_sz = args.ts_buf_sz;
> +
> +	m->si.pat = kzalloc(sizeof(*m->si.pat), GFP_KERNEL);
> +	m->si.sdt = kzalloc(sizeof(*m->si.sdt), GFP_KERNEL);
> +
> +	vidtv_channels_init(m);
> +
> +	/* will alloc data for pmt_sections after initializing pat */
> +	vidtv_channel_si_init(m);
> +
> +	INIT_WORK(&m->mpeg_thread, vidtv_mux_tick);
> +
> +	m->pcr_pid = args.pcr_pid;
> +	m->priv    = args.priv;
> +
> +	vidtv_mux_pid_ctx_init(m);
> +	vidtv_channels_add_registration_descs(m);
> +
> +	return m;
> +}
> +
> +void vidtv_mux_destroy(struct vidtv_mux *m)
> +{
> +	vidtv_mux_pid_ctx_destroy(m);
> +	vidtv_channel_si_destroy(m);
> +	vidtv_channels_destroy(m);
> +	kfree(m->si.sdt);
> +	kfree(m->si.pat);
> +	vfree(m->ts_buf);
> +	kfree(m);
> +}
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_mux.h b/drivers/media/test-drivers/vidtv/vidtv_mux.h
> new file mode 100644
> index 0000000000000..1dffa2010d518
> --- /dev/null
> +++ b/drivers/media/test-drivers/vidtv/vidtv_mux.h
> @@ -0,0 +1,105 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Vidtv 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.
> + *
> + * This file contains the multiplexer logic for TS packets from different
> + * elementary streams
> + *
> + * Written by Daniel W. S. Almeida <dwlsalmeida@gmail.com>
> + */
> +
> +#ifndef VIDTV_MUX_H
> +#define VIDTV_MUX_H
> +
> +#include <linux/types.h>
> +#include <linux/hashtable.h>
> +#include <linux/workqueue.h>
> +#include "vidtv_psi.h"
> +struct vidtv_mux_timing {
> +	u64 start_jiffies;
> +	u64 current_jiffies;
> +	u64 past_jiffies;
> +
> +	/* a 27Mhz clock from which we will drive the PCR */
> +	u64 clk;
> +
> +	u64 pcr_period_usecs;
> +	u64 si_period_usecs;
> +};
> +
> +struct vidtv_mux_si {
> +	/* the SI tables */
> +	struct vidtv_psi_table_pat *pat;
> +	struct vidtv_psi_table_pmt *pmt_secs; /* the PMT sections */
> +	/* as many sections as programs in the PAT */
> +	u16 num_pmt_sections;
> +	struct vidtv_psi_table_sdt *sdt;
> +};
> +
> +struct vidtv_mux_pid_ctx {
> +	u16 pid;
> +	u8 cc; /* continuity counter */
> +	struct hlist_node h;
> +};
> +
> +struct vidtv_mux {
> +	struct vidtv_mux_timing timing;
> +
> +	/* the bit rate for the TS, in kbytes */
> +	u32 mux_rate_kbytes_sec;
> +
> +	/* a hash table to keep track of per-PID metadata */
> +	DECLARE_HASHTABLE(pid_ctx, 3);
> +
> +	/* a callback to inform of new TS packets ready */
> +	void (*on_new_packets_available_cb)(void *priv, u8 *buf, u32 npackets);
> +
> +	/* the TS buffer */
> +	u8 *ts_buf;
> +
> +	/* the TS buffer size */
> +	u32 ts_buf_sz;
> +
> +	/* where we are in the TS buffer now */
> +	u32 ts_buf_offset;
> +
> +	/* a list of channels */
> +	struct vidtv_channel  *channels;
> +
> +	struct vidtv_mux_si si;
> +	u64 num_streamed_pcr;
> +	u64 num_streamed_si;
> +
> +	/* total number of packets streamed */
> +	u64 num_streamed_pkts;
> +
> +	struct work_struct mpeg_thread;
> +
> +	/* whether to keep running the main loop */
> +	bool streaming;
> +
> +	/* the pcr PID for _all_ channels */
> +	u16 pcr_pid;
> +
> +	void *priv;
> +};
> +
> +struct vidtv_mux_init_args {
> +	u32 mux_rate_kbytes_sec;
> +	void (*on_new_packets_available_cb)(void *priv, u8 *buf, u32 npackets);
> +	u32 ts_buf_sz;
> +	u64 pcr_period_usecs;
> +	u64 si_period_usecs;
> +	u16 pcr_pid;
> +	void *priv;
> +};
> +
> +struct vidtv_mux *vidtv_mux_init(struct vidtv_mux_init_args args);
> +void vidtv_mux_destroy(struct vidtv_mux *m);
> +
> +void vidtv_mux_start_thread(struct vidtv_mux *m);
> +void vidtv_mux_stop_thread(struct vidtv_mux *m);
> +
> +#endif //VIDTV_MUX_H
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_psi.c b/drivers/media/test-drivers/vidtv/vidtv_psi.c
> index 191d37a248923..ac7a52f03843a 100644
> --- a/drivers/media/test-drivers/vidtv/vidtv_psi.c
> +++ b/drivers/media/test-drivers/vidtv/vidtv_psi.c
> @@ -1135,3 +1135,21 @@ vidtv_psi_pmt_create_sec_for_each_pat_entry(struct vidtv_psi_table_pat *pat,
>  		program = program->next;
>  	}
>  }
> +
> +struct vidtv_psi_table_pmt
> +*vidtv_psi_find_pmt_sec(struct vidtv_psi_table_pmt pmt_sections[],
> +			u16 nsections,
> +			u16 program_num)
> +{
> +	/* find the PMT section associated with 'program_num' */
> +	struct vidtv_psi_table_pmt *sec = NULL;
> +	u32 i;
> +
> +	for (i = 0; i < nsections; ++i) {
> +		sec = &pmt_sections[i];
> +		if (sec->header.id == program_num)
> +			return sec;
> +	}
> +
> +	return NULL;
> +}
> diff --git a/drivers/media/test-drivers/vidtv/vidtv_psi.h b/drivers/media/test-drivers/vidtv/vidtv_psi.h
> index c5c8c143f0e4a..7aa502b89a2e2 100644
> --- a/drivers/media/test-drivers/vidtv/vidtv_psi.h
> +++ b/drivers/media/test-drivers/vidtv/vidtv_psi.h
> @@ -354,4 +354,9 @@ u32 vidtv_psi_pmt_write_into(char *buf,
>  			     u32 buf_sz,
>  			     u8 *continuity_counter);
>  
> +struct vidtv_psi_table_pmt
> +*vidtv_psi_find_pmt_sec(struct vidtv_psi_table_pmt *pmt_sections,
> +			u16 nsections,
> +			u16 program_num);
> +
>  #endif // VIDTV_PSI_H


Thanks,
Mauro