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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Vidtv serves as a reference DVB driver and helps validate the existing APIs
4 * in the media subsystem. It can also aid developers working on userspace
5 * applications.
6 *
7 * This file contains the muxer logic for TS packets from different
8 * elementary streams.
9 *
10 * Loosely based on libavcodec/mpegtsenc.c
11 *
12 * Copyright (C) 2020 Daniel W. S. Almeida
13 */
14
15#ifndef VIDTV_MUX_H
16#define VIDTV_MUX_H
17
18#include <linux/hashtable.h>
19#include <linux/types.h>
20#include <linux/workqueue.h>
21
22#include <media/dvb_frontend.h>
23
24#include "vidtv_psi.h"
25
26/**
27 * struct vidtv_mux_timing - Timing related information
28 *
29 * This is used to decide when PCR or PSI packets should be sent. This will also
30 * provide storage for the clock, which is used to compute the value for the PCR.
31 *
32 * @start_jiffies: The value of 'jiffies' when we started the mux thread.
33 * @current_jiffies: The value of 'jiffies' for the current iteration.
34 * @past_jiffies: The value of 'jiffies' for the past iteration.
35 * @clk: A 27Mhz clock from which we will drive the PCR. Updated proportionally
36 * on every iteration.
37 * @pcr_period_usecs: How often we should send PCR packets.
38 * @si_period_usecs: How often we should send PSI packets.
39 */
40struct vidtv_mux_timing {
41 u64 start_jiffies;
42 u64 current_jiffies;
43 u64 past_jiffies;
44
45 u64 clk;
46
47 u64 pcr_period_usecs;
48 u64 si_period_usecs;
49};
50
51/**
52 * struct vidtv_mux_si - Store the PSI context.
53 *
54 * This is used to store the PAT, PMT sections and SDT in use by the muxer.
55 *
56 * The muxer acquire these by looking into the hardcoded channels in
57 * vidtv_channel and then periodically sends the TS packets for them>
58 *
59 * @pat: The PAT in use by the muxer.
60 * @pmt_secs: The PMT sections in use by the muxer. One for each program in the PAT.
61 * @sdt: The SDT in use by the muxer.
62 * @nit: The NIT in use by the muxer.
63 * @eit: the EIT in use by the muxer.
64 */
65struct vidtv_mux_si {
66 /* the SI tables */
67 struct vidtv_psi_table_pat *pat;
68 struct vidtv_psi_table_pmt **pmt_secs; /* the PMT sections */
69 struct vidtv_psi_table_sdt *sdt;
70 struct vidtv_psi_table_nit *nit;
71 struct vidtv_psi_table_eit *eit;
72};
73
74/**
75 * struct vidtv_mux_pid_ctx - Store the context for a given TS PID.
76 * @pid: The TS PID.
77 * @cc: The continuity counter for this PID. It is incremented on every TS
78 * pack and it will wrap around at 0xf0. If the decoder notices a sudden jump in
79 * this counter this will trigger a discontinuity state.
80 * @h: This is embedded in a hash table, mapping pid -> vidtv_mux_pid_ctx
81 */
82struct vidtv_mux_pid_ctx {
83 u16 pid;
84 u8 cc; /* continuity counter */
85 struct hlist_node h;
86};
87
88/**
89 * struct vidtv_mux - A muxer abstraction loosely based in libavcodec/mpegtsenc.c
90 * @fe: The frontend structure allocated by the muxer.
91 * @dev: pointer to struct device.
92 * @timing: Keeps track of timing related information.
93 * @mux_rate_kbytes_sec: The bit rate for the TS, in kbytes.
94 * @pid_ctx: A hash table to keep track of per-PID metadata.
95 * @on_new_packets_available_cb: A callback to inform of new TS packets ready.
96 * @mux_buf: A pointer to a buffer for this muxer. TS packets are stored there
97 * and then passed on to the bridge driver.
98 * @mux_buf_sz: The size for 'mux_buf'.
99 * @mux_buf_offset: The current offset into 'mux_buf'.
100 * @channels: The channels associated with this muxer.
101 * @si: Keeps track of the PSI context.
102 * @num_streamed_pcr: Number of PCR packets streamed.
103 * @num_streamed_si: The number of PSI packets streamed.
104 * @mpeg_thread: Thread responsible for the muxer loop.
105 * @streaming: whether 'mpeg_thread' is running.
106 * @pcr_pid: The TS PID used for the PSI packets. All channels will share the
107 * same PCR.
108 * @transport_stream_id: The transport stream ID
109 * @network_id: The network ID
110 * @network_name: The network name
111 * @priv: Private data.
112 */
113struct vidtv_mux {
114 struct dvb_frontend *fe;
115 struct device *dev;
116
117 struct vidtv_mux_timing timing;
118
119 u32 mux_rate_kbytes_sec;
120
121 DECLARE_HASHTABLE(pid_ctx, 3);
122
123 void (*on_new_packets_available_cb)(void *priv, u8 *buf, u32 npackets);
124
125 u8 *mux_buf;
126 u32 mux_buf_sz;
127 u32 mux_buf_offset;
128
129 struct vidtv_channel *channels;
130
131 struct vidtv_mux_si si;
132 u64 num_streamed_pcr;
133 u64 num_streamed_si;
134
135 struct work_struct mpeg_thread;
136 bool streaming;
137
138 u16 pcr_pid;
139 u16 transport_stream_id;
140 u16 network_id;
141 char *network_name;
142 void *priv;
143};
144
145/**
146 * struct vidtv_mux_init_args - Arguments used to inix the muxer.
147 * @mux_rate_kbytes_sec: The bit rate for the TS, in kbytes.
148 * @on_new_packets_available_cb: A callback to inform of new TS packets ready.
149 * @mux_buf_sz: The size for 'mux_buf'.
150 * @pcr_period_usecs: How often we should send PCR packets.
151 * @si_period_usecs: How often we should send PSI packets.
152 * @pcr_pid: The TS PID used for the PSI packets. All channels will share the
153 * same PCR.
154 * @transport_stream_id: The transport stream ID
155 * @channels: an optional list of channels to use
156 * @network_id: The network ID
157 * @network_name: The network name
158 * @priv: Private data.
159 */
160struct vidtv_mux_init_args {
161 u32 mux_rate_kbytes_sec;
162 void (*on_new_packets_available_cb)(void *priv, u8 *buf, u32 npackets);
163 u32 mux_buf_sz;
164 u64 pcr_period_usecs;
165 u64 si_period_usecs;
166 u16 pcr_pid;
167 u16 transport_stream_id;
168 struct vidtv_channel *channels;
169 u16 network_id;
170 char *network_name;
171 void *priv;
172};
173
174struct vidtv_mux *vidtv_mux_init(struct dvb_frontend *fe,
175 struct device *dev,
176 struct vidtv_mux_init_args *args);
177void vidtv_mux_destroy(struct vidtv_mux *m);
178
179void vidtv_mux_start_thread(struct vidtv_mux *m);
180void vidtv_mux_stop_thread(struct vidtv_mux *m);
181
182#endif //VIDTV_MUX_H