linux/drivers/media/test-drivers/vidtv/vidtv_s302m.c

// 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 an AES3 (also known as AES/EBU) encoder.
 * It is based on EBU Tech 3250 and SMPTE 302M technical documents.
 *
 * This encoder currently supports 16bit AES3 subframes using 16bit signed
 * integers.
 *
 * Note: AU stands for Access Unit, and AAU stands for Audio Access Unit
 *
 * Copyright (C) 2020 Daniel W. S. Almeida
 */

#define pr_fmt(fmt) KBUILD_MODNAME ":%s, %d: " fmt, __func__, __LINE__

#include <linux/types.h>
#include <linux/slab.h>
#include <linux/crc32.h>
#include <linux/vmalloc.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/jiffies.h>
#include <linux/printk.h>
#include <linux/ratelimit.h>
#include <linux/math64.h>
#include <asm/byteorder.h>

#include "vidtv_s302m.h"
#include "vidtv_encoder.h"
#include "vidtv_common.h"

#define S302M_SAMPLING_RATE_HZ 48000
#define PES_PRIVATE_STREAM_1 0xbd  /* PES: private_stream_1 */
#define S302M_BLOCK_SZ 192
#define S302M_SIN_LUT_NUM_ELEM 1024

static const u8 reverse[256] = {
	/* from ffmpeg */
	0x00, 0x80, 0x40, 0xC0, 0x20, 0xA0, 0x60, 0xE0, 0x10, 0x90, 0x50, 0xD0,
	0x30, 0xB0, 0x70, 0xF0, 0x08, 0x88, 0x48, 0xC8, 0x28, 0xA8, 0x68, 0xE8,
	0x18, 0x98, 0x58, 0xD8, 0x38, 0xB8, 0x78, 0xF8, 0x04, 0x84, 0x44, 0xC4,
	0x24, 0xA4, 0x64, 0xE4, 0x14, 0x94, 0x54, 0xD4, 0x34, 0xB4, 0x74, 0xF4,
	0x0C, 0x8C, 0x4C, 0xCC, 0x2C, 0xAC, 0x6C, 0xEC, 0x1C, 0x9C, 0x5C, 0xDC,
	0x3C, 0xBC, 0x7C, 0xFC, 0x02, 0x82, 0x42, 0xC2, 0x22, 0xA2, 0x62, 0xE2,
	0x12, 0x92, 0x52, 0xD2, 0x32, 0xB2, 0x72, 0xF2, 0x0A, 0x8A, 0x4A, 0xCA,
	0x2A, 0xAA, 0x6A, 0xEA, 0x1A, 0x9A, 0x5A, 0xDA, 0x3A, 0xBA, 0x7A, 0xFA,
	0x06, 0x86, 0x46, 0xC6, 0x26, 0xA6, 0x66, 0xE6, 0x16, 0x96, 0x56, 0xD6,
	0x36, 0xB6, 0x76, 0xF6, 0x0E, 0x8E, 0x4E, 0xCE, 0x2E, 0xAE, 0x6E, 0xEE,
	0x1E, 0x9E, 0x5E, 0xDE, 0x3E, 0xBE, 0x7E, 0xFE, 0x01, 0x81, 0x41, 0xC1,
	0x21, 0xA1, 0x61, 0xE1, 0x11, 0x91, 0x51, 0xD1, 0x31, 0xB1, 0x71, 0xF1,
	0x09, 0x89, 0x49, 0xC9, 0x29, 0xA9, 0x69, 0xE9, 0x19, 0x99, 0x59, 0xD9,
	0x39, 0xB9, 0x79, 0xF9, 0x05, 0x85, 0x45, 0xC5, 0x25, 0xA5, 0x65, 0xE5,
	0x15, 0x95, 0x55, 0xD5, 0x35, 0xB5, 0x75, 0xF5, 0x0D, 0x8D, 0x4D, 0xCD,
	0x2D, 0xAD, 0x6D, 0xED, 0x1D, 0x9D, 0x5D, 0xDD, 0x3D, 0xBD, 0x7D, 0xFD,
	0x03, 0x83, 0x43, 0xC3, 0x23, 0xA3, 0x63, 0xE3, 0x13, 0x93, 0x53, 0xD3,
	0x33, 0xB3, 0x73, 0xF3, 0x0B, 0x8B, 0x4B, 0xCB, 0x2B, 0xAB, 0x6B, 0xEB,
	0x1B, 0x9B, 0x5B, 0xDB, 0x3B, 0xBB, 0x7B, 0xFB, 0x07, 0x87, 0x47, 0xC7,
	0x27, 0xA7, 0x67, 0xE7, 0x17, 0x97, 0x57, 0xD7, 0x37, 0xB7, 0x77, 0xF7,
	0x0F, 0x8F, 0x4F, 0xCF, 0x2F, 0xAF, 0x6F, 0xEF, 0x1F, 0x9F, 0x5F, 0xDF,
	0x3F, 0xBF, 0x7F, 0xFF,
};

/*
 * This buffer contains PCM audio samples of a sine wave, compatible with
 * S302. If this is used as a source, a userspace media application should be able
 * to play it.
 */
static u16 s302m_sin_lut[S302M_SIN_LUT_NUM_ELEM] = {
	0x8000, 0x80c9, 0x8192, 0x825b, 0x8324, 0x83ed, 0x84b6, 0x857e,
	0x8647, 0x8710, 0x87d9, 0x88a1, 0x896a, 0x8a32, 0x8afb, 0x8bc3,
	0x8c8b, 0x8d53, 0x8e1b, 0x8ee3, 0x8fab, 0x9072, 0x9139, 0x9201,
	0x92c7, 0x938e, 0x9455, 0x951b, 0x95e1, 0x96a7, 0x976d, 0x9833,
	0x98f8, 0x99bd, 0x9a82, 0x9b47, 0x9c0b, 0x9ccf, 0x9d93, 0x9e56,
	0x9f19, 0x9fdc, 0xa09f, 0xa161, 0xa223, 0xa2e5, 0xa3a6, 0xa467,
	0xa527, 0xa5e8, 0xa6a7, 0xa767, 0xa826, 0xa8e5, 0xa9a3, 0xaa61,
	0xab1f, 0xabdc, 0xac98, 0xad55, 0xae10, 0xaecc, 0xaf87, 0xb041,
	0xb0fb, 0xb1b5, 0xb26e, 0xb326, 0xb3de, 0xb496, 0xb54d, 0xb603,
	0xb6b9, 0xb76f, 0xb824, 0xb8d8, 0xb98c, 0xba3f, 0xbaf2, 0xbba4,
	0xbc56, 0xbd07, 0xbdb7, 0xbe67, 0xbf17, 0xbfc5, 0xc073, 0xc121,
	0xc1cd, 0xc279, 0xc325, 0xc3d0, 0xc47a, 0xc524, 0xc5cc, 0xc675,
	0xc71c, 0xc7c3, 0xc869, 0xc90f, 0xc9b3, 0xca57, 0xcafb, 0xcb9d,
	0xcc3f, 0xcce0, 0xcd81, 0xce20, 0xcebf, 0xcf5d, 0xcffb, 0xd097,
	0xd133, 0xd1ce, 0xd268, 0xd302, 0xd39a, 0xd432, 0xd4c9, 0xd55f,
	0xd5f5, 0xd689, 0xd71d, 0xd7b0, 0xd842, 0xd8d3, 0xd964, 0xd9f3,
	0xda82, 0xdb0f, 0xdb9c, 0xdc28, 0xdcb3, 0xdd3d, 0xddc7, 0xde4f,
	0xded7, 0xdf5d, 0xdfe3, 0xe068, 0xe0eb, 0xe16e, 0xe1f0, 0xe271,
	0xe2f1, 0xe370, 0xe3ee, 0xe46b, 0xe4e8, 0xe563, 0xe5dd, 0xe656,
	0xe6cf, 0xe746, 0xe7bc, 0xe831, 0xe8a6, 0xe919, 0xe98b, 0xe9fc,
	0xea6d, 0xeadc, 0xeb4a, 0xebb7, 0xec23, 0xec8e, 0xecf8, 0xed61,
	0xedc9, 0xee30, 0xee96, 0xeefa, 0xef5e, 0xefc1, 0xf022, 0xf083,
	0xf0e2, 0xf140, 0xf19d, 0xf1f9, 0xf254, 0xf2ae, 0xf307, 0xf35e,
	0xf3b5, 0xf40a, 0xf45f, 0xf4b2, 0xf504, 0xf555, 0xf5a5, 0xf5f3,
	0xf641, 0xf68d, 0xf6d8, 0xf722, 0xf76b, 0xf7b3, 0xf7fa, 0xf83f,
	0xf884, 0xf8c7, 0xf909, 0xf94a, 0xf989, 0xf9c8, 0xfa05, 0xfa41,
	0xfa7c, 0xfab6, 0xfaee, 0xfb26, 0xfb5c, 0xfb91, 0xfbc5, 0xfbf8,
	0xfc29, 0xfc59, 0xfc88, 0xfcb6, 0xfce3, 0xfd0e, 0xfd39, 0xfd62,
	0xfd89, 0xfdb0, 0xfdd5, 0xfdfa, 0xfe1d, 0xfe3e, 0xfe5f, 0xfe7e,
	0xfe9c, 0xfeb9, 0xfed5, 0xfeef, 0xff09, 0xff21, 0xff37, 0xff4d,
	0xff61, 0xff74, 0xff86, 0xff97, 0xffa6, 0xffb4, 0xffc1, 0xffcd,
	0xffd8, 0xffe1, 0xffe9, 0xfff0, 0xfff5, 0xfff9, 0xfffd, 0xfffe,
	0xffff, 0xfffe, 0xfffd, 0xfff9, 0xfff5, 0xfff0, 0xffe9, 0xffe1,
	0xffd8, 0xffcd, 0xffc1, 0xffb4, 0xffa6, 0xff97, 0xff86, 0xff74,
	0xff61, 0xff4d, 0xff37, 0xff21, 0xff09, 0xfeef, 0xfed5, 0xfeb9,
	0xfe9c, 0xfe7e, 0xfe5f, 0xfe3e, 0xfe1d, 0xfdfa, 0xfdd5, 0xfdb0,
	0xfd89, 0xfd62, 0xfd39, 0xfd0e, 0xfce3, 0xfcb6, 0xfc88, 0xfc59,
	0xfc29, 0xfbf8, 0xfbc5, 0xfb91, 0xfb5c, 0xfb26, 0xfaee, 0xfab6,
	0xfa7c, 0xfa41, 0xfa05, 0xf9c8, 0xf989, 0xf94a, 0xf909, 0xf8c7,
	0xf884, 0xf83f, 0xf7fa, 0xf7b3, 0xf76b, 0xf722, 0xf6d8, 0xf68d,
	0xf641, 0xf5f3, 0xf5a5, 0xf555, 0xf504, 0xf4b2, 0xf45f, 0xf40a,
	0xf3b5, 0xf35e, 0xf307, 0xf2ae, 0xf254, 0xf1f9, 0xf19d, 0xf140,
	0xf0e2, 0xf083, 0xf022, 0xefc1, 0xef5e, 0xeefa, 0xee96, 0xee30,
	0xedc9, 0xed61, 0xecf8, 0xec8e, 0xec23, 0xebb7, 0xeb4a, 0xeadc,
	0xea6d, 0xe9fc, 0xe98b, 0xe919, 0xe8a6, 0xe831, 0xe7bc, 0xe746,
	0xe6cf, 0xe656, 0xe5dd, 0xe563, 0xe4e8, 0xe46b, 0xe3ee, 0xe370,
	0xe2f1, 0xe271, 0xe1f0, 0xe16e, 0xe0eb, 0xe068, 0xdfe3, 0xdf5d,
	0xded7, 0xde4f, 0xddc7, 0xdd3d, 0xdcb3, 0xdc28, 0xdb9c, 0xdb0f,
	0xda82, 0xd9f3, 0xd964, 0xd8d3, 0xd842, 0xd7b0, 0xd71d, 0xd689,
	0xd5f5, 0xd55f, 0xd4c9, 0xd432, 0xd39a, 0xd302, 0xd268, 0xd1ce,
	0xd133, 0xd097, 0xcffb, 0xcf5d, 0xcebf, 0xce20, 0xcd81, 0xcce0,
	0xcc3f, 0xcb9d, 0xcafb, 0xca57, 0xc9b3, 0xc90f, 0xc869, 0xc7c3,
	0xc71c, 0xc675, 0xc5cc, 0xc524, 0xc47a, 0xc3d0, 0xc325, 0xc279,
	0xc1cd, 0xc121, 0xc073, 0xbfc5, 0xbf17, 0xbe67, 0xbdb7, 0xbd07,
	0xbc56, 0xbba4, 0xbaf2, 0xba3f, 0xb98c, 0xb8d8, 0xb824, 0xb76f,
	0xb6b9, 0xb603, 0xb54d, 0xb496, 0xb3de, 0xb326, 0xb26e, 0xb1b5,
	0xb0fb, 0xb041, 0xaf87, 0xaecc, 0xae10, 0xad55, 0xac98, 0xabdc,
	0xab1f, 0xaa61, 0xa9a3, 0xa8e5, 0xa826, 0xa767, 0xa6a7, 0xa5e8,
	0xa527, 0xa467, 0xa3a6, 0xa2e5, 0xa223, 0xa161, 0xa09f, 0x9fdc,
	0x9f19, 0x9e56, 0x9d93, 0x9ccf, 0x9c0b, 0x9b47, 0x9a82, 0x99bd,
	0x98f8, 0x9833, 0x976d, 0x96a7, 0x95e1, 0x951b, 0x9455, 0x938e,
	0x92c7, 0x9201, 0x9139, 0x9072, 0x8fab, 0x8ee3, 0x8e1b, 0x8d53,
	0x8c8b, 0x8bc3, 0x8afb, 0x8a32, 0x896a, 0x88a1, 0x87d9, 0x8710,
	0x8647, 0x857e, 0x84b6, 0x83ed, 0x8324, 0x825b, 0x8192, 0x80c9,
	0x8000, 0x7f36, 0x7e6d, 0x7da4, 0x7cdb, 0x7c12, 0x7b49, 0x7a81,
	0x79b8, 0x78ef, 0x7826, 0x775e, 0x7695, 0x75cd, 0x7504, 0x743c,
	0x7374, 0x72ac, 0x71e4, 0x711c, 0x7054, 0x6f8d, 0x6ec6, 0x6dfe,
	0x6d38, 0x6c71, 0x6baa, 0x6ae4, 0x6a1e, 0x6958, 0x6892, 0x67cc,
	0x6707, 0x6642, 0x657d, 0x64b8, 0x63f4, 0x6330, 0x626c, 0x61a9,
	0x60e6, 0x6023, 0x5f60, 0x5e9e, 0x5ddc, 0x5d1a, 0x5c59, 0x5b98,
	0x5ad8, 0x5a17, 0x5958, 0x5898, 0x57d9, 0x571a, 0x565c, 0x559e,
	0x54e0, 0x5423, 0x5367, 0x52aa, 0x51ef, 0x5133, 0x5078, 0x4fbe,
	0x4f04, 0x4e4a, 0x4d91, 0x4cd9, 0x4c21, 0x4b69, 0x4ab2, 0x49fc,
	0x4946, 0x4890, 0x47db, 0x4727, 0x4673, 0x45c0, 0x450d, 0x445b,
	0x43a9, 0x42f8, 0x4248, 0x4198, 0x40e8, 0x403a, 0x3f8c, 0x3ede,
	0x3e32, 0x3d86, 0x3cda, 0x3c2f, 0x3b85, 0x3adb, 0x3a33, 0x398a,
	0x38e3, 0x383c, 0x3796, 0x36f0, 0x364c, 0x35a8, 0x3504, 0x3462,
	0x33c0, 0x331f, 0x327e, 0x31df, 0x3140, 0x30a2, 0x3004, 0x2f68,
	0x2ecc, 0x2e31, 0x2d97, 0x2cfd, 0x2c65, 0x2bcd, 0x2b36, 0x2aa0,
	0x2a0a, 0x2976, 0x28e2, 0x284f, 0x27bd, 0x272c, 0x269b, 0x260c,
	0x257d, 0x24f0, 0x2463, 0x23d7, 0x234c, 0x22c2, 0x2238, 0x21b0,
	0x2128, 0x20a2, 0x201c, 0x1f97, 0x1f14, 0x1e91, 0x1e0f, 0x1d8e,
	0x1d0e, 0x1c8f, 0x1c11, 0x1b94, 0x1b17, 0x1a9c, 0x1a22, 0x19a9,
	0x1930, 0x18b9, 0x1843, 0x17ce, 0x1759, 0x16e6, 0x1674, 0x1603,
	0x1592, 0x1523, 0x14b5, 0x1448, 0x13dc, 0x1371, 0x1307, 0x129e,
	0x1236, 0x11cf, 0x1169, 0x1105, 0x10a1, 0x103e, 0xfdd, 0xf7c,
	0xf1d, 0xebf, 0xe62, 0xe06, 0xdab, 0xd51, 0xcf8, 0xca1,
	0xc4a, 0xbf5, 0xba0, 0xb4d, 0xafb, 0xaaa, 0xa5a, 0xa0c,
	0x9be, 0x972, 0x927, 0x8dd, 0x894, 0x84c, 0x805, 0x7c0,
	0x77b, 0x738, 0x6f6, 0x6b5, 0x676, 0x637, 0x5fa, 0x5be,
	0x583, 0x549, 0x511, 0x4d9, 0x4a3, 0x46e, 0x43a, 0x407,
	0x3d6, 0x3a6, 0x377, 0x349, 0x31c, 0x2f1, 0x2c6, 0x29d,
	0x276, 0x24f, 0x22a, 0x205, 0x1e2, 0x1c1, 0x1a0, 0x181,
	0x163, 0x146, 0x12a, 0x110, 0xf6, 0xde, 0xc8, 0xb2,
	0x9e, 0x8b, 0x79, 0x68, 0x59, 0x4b, 0x3e, 0x32,
	0x27, 0x1e, 0x16, 0xf, 0xa, 0x6, 0x2, 0x1,
	0x0, 0x1, 0x2, 0x6, 0xa, 0xf, 0x16, 0x1e,
	0x27, 0x32, 0x3e, 0x4b, 0x59, 0x68, 0x79, 0x8b,
	0x9e, 0xb2, 0xc8, 0xde, 0xf6, 0x110, 0x12a, 0x146,
	0x163, 0x181, 0x1a0, 0x1c1, 0x1e2, 0x205, 0x22a, 0x24f,
	0x276, 0x29d, 0x2c6, 0x2f1, 0x31c, 0x349, 0x377, 0x3a6,
	0x3d6, 0x407, 0x43a, 0x46e, 0x4a3, 0x4d9, 0x511, 0x549,
	0x583, 0x5be, 0x5fa, 0x637, 0x676, 0x6b5, 0x6f6, 0x738,
	0x77b, 0x7c0, 0x805, 0x84c, 0x894, 0x8dd, 0x927, 0x972,
	0x9be, 0xa0c, 0xa5a, 0xaaa, 0xafb, 0xb4d, 0xba0, 0xbf5,
	0xc4a, 0xca1, 0xcf8, 0xd51, 0xdab, 0xe06, 0xe62, 0xebf,
	0xf1d, 0xf7c, 0xfdd, 0x103e, 0x10a1, 0x1105, 0x1169, 0x11cf,
	0x1236, 0x129e, 0x1307, 0x1371, 0x13dc, 0x1448, 0x14b5, 0x1523,
	0x1592, 0x1603, 0x1674, 0x16e6, 0x1759, 0x17ce, 0x1843, 0x18b9,
	0x1930, 0x19a9, 0x1a22, 0x1a9c, 0x1b17, 0x1b94, 0x1c11, 0x1c8f,
	0x1d0e, 0x1d8e, 0x1e0f, 0x1e91, 0x1f14, 0x1f97, 0x201c, 0x20a2,
	0x2128, 0x21b0, 0x2238, 0x22c2, 0x234c, 0x23d7, 0x2463, 0x24f0,
	0x257d, 0x260c, 0x269b, 0x272c, 0x27bd, 0x284f, 0x28e2, 0x2976,
	0x2a0a, 0x2aa0, 0x2b36, 0x2bcd, 0x2c65, 0x2cfd, 0x2d97, 0x2e31,
	0x2ecc, 0x2f68, 0x3004, 0x30a2, 0x3140, 0x31df, 0x327e, 0x331f,
	0x33c0, 0x3462, 0x3504, 0x35a8, 0x364c, 0x36f0, 0x3796, 0x383c,
	0x38e3, 0x398a, 0x3a33, 0x3adb, 0x3b85, 0x3c2f, 0x3cda, 0x3d86,
	0x3e32, 0x3ede, 0x3f8c, 0x403a, 0x40e8, 0x4198, 0x4248, 0x42f8,
	0x43a9, 0x445b, 0x450d, 0x45c0, 0x4673, 0x4727, 0x47db, 0x4890,
	0x4946, 0x49fc, 0x4ab2, 0x4b69, 0x4c21, 0x4cd9, 0x4d91, 0x4e4a,
	0x4f04, 0x4fbe, 0x5078, 0x5133, 0x51ef, 0x52aa, 0x5367, 0x5423,
	0x54e0, 0x559e, 0x565c, 0x571a, 0x57d9, 0x5898, 0x5958, 0x5a17,
	0x5ad8, 0x5b98, 0x5c59, 0x5d1a, 0x5ddc, 0x5e9e, 0x5f60, 0x6023,
	0x60e6, 0x61a9, 0x626c, 0x6330, 0x63f4, 0x64b8, 0x657d, 0x6642,
	0x6707, 0x67cc, 0x6892, 0x6958, 0x6a1e, 0x6ae4, 0x6baa, 0x6c71,
	0x6d38, 0x6dfe, 0x6ec6, 0x6f8d, 0x7054, 0x711c, 0x71e4, 0x72ac,
	0x7374, 0x743c, 0x7504, 0x75cd, 0x7695, 0x775e, 0x7826, 0x78ef,
	0x79b8, 0x7a81, 0x7b49, 0x7c12, 0x7cdb, 0x7da4, 0x7e6d, 0x7f36
};

static struct vidtv_access_unit *vidtv_s302m_access_unit_init(struct vidtv_access_unit *head)
{
	struct vidtv_access_unit *au = kzalloc(sizeof(*au), GFP_KERNEL);

	if (head) {
		while (head->next)
			head = head->next;

		head->next = au;
	}

	return au;
}

static void vidtv_s302m_access_unit_destroy(struct vidtv_encoder *e)
{
	struct vidtv_access_unit *head = e->access_units;
	struct vidtv_access_unit *tmp = NULL;

	while (head) {
		tmp = head;
		head = head->next;
		kfree(tmp);
	}

	e->access_units = NULL;
}

static void vidtv_s302m_alloc_au(struct vidtv_encoder *e)
{
	struct vidtv_access_unit *sync_au = NULL;
	struct vidtv_access_unit *temp = NULL;

	if (e->sync && e->sync->is_video_encoder) {
		sync_au = e->sync->access_units;

		while (sync_au) {
			temp = vidtv_s302m_access_unit_init(e->access_units);
			if (!e->access_units)
				e->access_units = temp;

			sync_au = sync_au->next;
		}

		return;
	}

	e->access_units = vidtv_s302m_access_unit_init(NULL);
}

static void
vidtv_s302m_compute_sample_count_v(struct vidtv_encoder *e)
{
	struct vidtv_access_unit *au = e->access_units;
	struct vidtv_access_unit *sync_au = e->sync->access_units;
	u32 vau_duration_usecs;
	u32 sample_duration_usecs;
	u32 s;

	vau_duration_usecs    = USEC_PER_SEC / e->sync->sampling_rate_hz;
	sample_duration_usecs = USEC_PER_SEC / e->sampling_rate_hz;

	while (au && sync_au) {
		s = DIV_ROUND_UP(vau_duration_usecs, sample_duration_usecs);
		au->num_samples = s;
		au = au->next;
		sync_au = sync_au->next;
	}
}

static void
vidtv_s302m_compute_sample_count(struct vidtv_encoder *e,
				 u64 elapsed_time_usecs)
{
	/* compute sample count for 'elapsed_time_usecs' */
	u32 sample_duration_usecs = USEC_PER_SEC / e->sampling_rate_hz;
	struct vidtv_access_unit *au = e->access_units;

	au->num_samples = (u32)div64_u64(elapsed_time_usecs, sample_duration_usecs);
}

static void vidtv_s302m_compute_pts(struct vidtv_encoder *e)
{
	u64 count = e->sample_count;
	struct vidtv_access_unit *au = e->access_units;

	while (au) {
		count += au->num_samples;

		au->pts = count *
			  CLOCK_UNIT_90KHZ / e->sampling_rate_hz;

		au = au->next;
	}
}

static void vidtv_s302m_compute_pts_v(struct vidtv_encoder *e)
{
	struct vidtv_access_unit *au = e->access_units;
	struct vidtv_access_unit *sync_au = e->sync->access_units;

	/* use the same pts from the video access unit*/
	while (au && sync_au) {
		au->pts = sync_au->pts;
		au = au->next;
		sync_au = sync_au->next;
	}
}

static u16 vidtv_s302m_get_sample(struct vidtv_encoder *e)
{
	u16 sample;

	/* bug somewhere */
	if (e->src_buf_offset > e->src_buf_sz) {
		pr_err_ratelimited("overflow detected: %d > %d, wrapping.\n",
				   e->src_buf_offset,
				   e->src_buf_sz);

		e->src_buf_offset = 0;
	}

	if (e->src_buf_offset >= e->src_buf_sz) {
		/* let the source know we are out of data */
		if (e->last_sample_cb)
			e->last_sample_cb(e->sample_count);

		e->src_buf_offset = 0;
	}

	sample = *(u16 *)(e->src_buf + e->src_buf_offset);

	return sample;
}

static u32 vidtv_s302m_write_frame(struct vidtv_encoder *e,
				   u16 sample)
{
	u32 nbytes = 0;
	struct vidtv_s302m_frame_16 f = {};
	struct vidtv_s302m_ctx *ctx = e->ctx;

	/* from ffmpeg: see s302enc.c */

	u8 vucf = ctx->frame_index == 0 ? 0x10 : 0;

	f.data[0] = sample & 0xFF;
	f.data[1] = (sample & 0xFF00) >>  8;
	f.data[2] = ((sample & 0x0F)  <<  4) | vucf;
	f.data[3] = (sample & 0x0FF0) >>  4;
	f.data[4] = (sample & 0xF000) >> 12;

	#ifdef __LITTLE_ENDIAN
	f.data[0] = reverse[f.data[0]];
	f.data[1] = reverse[f.data[1]];
	f.data[2] = reverse[f.data[2]];
	f.data[3] = reverse[f.data[3]];
	f.data[4] = reverse[f.data[4]];
	#endif

	nbytes += vidtv_memcpy(e->encoder_buf,
			       e->encoder_buf_offset,
			       VIDTV_S302M_BUF_SZ,
			       &f,
			       sizeof(f));

	e->encoder_buf_offset += nbytes;

	ctx->frame_index++;
	if (ctx->frame_index >= S302M_BLOCK_SZ)
		ctx->frame_index = 0;

	return nbytes;
}

static u32 vidtv_s302m_write_h(struct vidtv_encoder *e, u32 p_sz)
{
	struct vidtv_smpte_s302m_es h = {};
	u32 nbytes = 0;

	/* 2 channels, ident: 0, 16 bits per sample */
	h.bitfield = cpu_to_be32((p_sz << 16));

	nbytes += vidtv_memcpy(e->encoder_buf,
			       e->encoder_buf_offset,
			       e->encoder_buf_sz,
			       &h,
			       sizeof(h));

	e->encoder_buf_offset += nbytes;
	return nbytes;
}

static void vidtv_s302m_write_frames(struct vidtv_encoder *e)
{
	u32 nbytes = 0;
	u32 nbytes_per_unit = 0;
	u32 au_sz = 0;

	struct vidtv_access_unit *au = e->access_units;

	u16 sample = 0;

	u32 j;

	while (au) {
		au_sz = au->num_samples *
			sizeof(struct vidtv_s302m_frame_16);

		nbytes_per_unit = vidtv_s302m_write_h(e, au_sz);

		for (j = 0; j < au->num_samples; ++j) {
			sample = vidtv_s302m_get_sample(e);
			nbytes_per_unit += vidtv_s302m_write_frame(e, sample);

			e->sample_count++;
			e->src_buf_offset += sizeof(u16);
		}

		au->nbytes = nbytes_per_unit;

		if (au_sz + sizeof(struct vidtv_smpte_s302m_es) != nbytes_per_unit) {
			pr_warn_ratelimited("write size was %u, expected %zu\n",
					    nbytes_per_unit,
					    au_sz + sizeof(struct vidtv_smpte_s302m_es));
		}

		nbytes += nbytes_per_unit;
		au->offset = nbytes - nbytes_per_unit;

		nbytes_per_unit = 0;

		au = au->next;
	}
}

static void *vidtv_s302m_encode(struct vidtv_encoder *e, u64 elapsed_time)
{
	/*
	 * According to SMPTE 302M, an audio access unit is specified as those
	 * AES3 words that are associated with a corresponding video frame.
	 * Therefore, there is one audio access unit for every video access unit
	 * in the corresponding video encoder ('sync'), using the same values
	 * for PTS as used by the video encoder.
	 *
	 * Assuming that it is also possible to send audio without any
	 * associated video, as in a radio-like service, a single audio access unit
	 * is created with enough audio data for 'elapsed_time'
	 * The value of PTS is computed manually.
	 */

	if (!elapsed_time)
		goto out;

	vidtv_s302m_access_unit_destroy(e);
	vidtv_s302m_alloc_au(e);

	if (e->sync && e->sync->is_video_encoder) {
		vidtv_s302m_compute_sample_count_v(e);
		vidtv_s302m_compute_pts_v(e);
	} else {
		vidtv_s302m_compute_sample_count(e, elapsed_time);
		vidtv_s302m_compute_pts(e);
	}

	vidtv_s302m_write_frames(e);

out:
	return e->encoder_buf;
}

static u32 vidtv_s302m_clear(struct vidtv_encoder *e)
{
	struct vidtv_access_unit *au = e->access_units;
	u32 count = 0;

	while (au) {
		count++;
		au = au->next;
	}

	vidtv_s302m_access_unit_destroy(e);
	memset(e->encoder_buf, 0, VIDTV_S302M_BUF_SZ);
	e->encoder_buf_offset = 0;

	return count;
}

struct vidtv_encoder
*vidtv_s302m_encoder_init(struct vidtv_s302m_encoder_init_args args)
{
	struct vidtv_encoder *e = kzalloc(sizeof(*e), GFP_KERNEL);
	u32 priv_sz = sizeof(struct vidtv_s302m_ctx);

	e->id = S302M;

	if (args.name)
		e->name = kstrdup(args.name, GFP_KERNEL);

	e->encoder_buf = vzalloc(VIDTV_S302M_BUF_SZ);
	e->encoder_buf_sz = VIDTV_S302M_BUF_SZ;
	e->encoder_buf_offset = 0;

	e->sample_count = 0;

	e->src_buf = (args.src_buf) ? args.src_buf : &s302m_sin_lut;
	e->src_buf_sz = (args.src_buf) ? args.src_buf_sz : S302M_SIN_LUT_NUM_ELEM * sizeof(u16);
	e->src_buf_offset = 0;

	e->is_video_encoder = false;
	e->ctx = kzalloc(priv_sz, GFP_KERNEL);

	e->encode = vidtv_s302m_encode;
	e->clear = vidtv_s302m_clear;

	e->es_pid = cpu_to_be16(args.es_pid);
	e->stream_id = cpu_to_be16(PES_PRIVATE_STREAM_1);

	e->sync = args.sync;
	e->sampling_rate_hz = S302M_SAMPLING_RATE_HZ;

	e->last_sample_cb = args.last_sample_cb;

	e->destroy = vidtv_s302m_encoder_destroy;

	if (args.head) {
		while (args.head->next)
			args.head = args.head->next;

		args.head->next = e;
	}

	e->next = NULL;

	return e;
}

void vidtv_s302m_encoder_destroy(struct vidtv_encoder *e)
{
	if (e->id != S302M) {
		pr_err_ratelimited("Encoder type mismatch, skipping.\n");
		return;
	}

	vidtv_s302m_access_unit_destroy(e);
	kfree(e->name);
	vfree(e->encoder_buf);
	kfree(e->ctx);
	kfree(e);
}