1/* SPDX-License-Identifier: GPL-2.0-only */
  2/*
  3 * V4L2 JPEG helpers header
  4 *
  5 * Copyright (C) 2019 Pengutronix, Philipp Zabel <kernel@pengutronix.de>
  6 *
  7 * For reference, see JPEG ITU-T.81 (ISO/IEC 10918-1)
  8 */
  9
 10#ifndef _V4L2_JPEG_H
 11#define _V4L2_JPEG_H
 12
 13#include <linux/v4l2-controls.h>
 14
 15#define V4L2_JPEG_MAX_COMPONENTS	4
 16#define V4L2_JPEG_MAX_TABLES		4
 17
 18/**
 19 * struct v4l2_jpeg_reference - reference into the JPEG buffer
 20 * @start: pointer to the start of the referenced segment or table
 21 * @length: size of the referenced segment or table
 22 *
 23 * Wnen referencing marker segments, start points right after the marker code,
 24 * and length is the size of the segment parameters, excluding the marker code.
 25 */
 26struct v4l2_jpeg_reference {
 27	u8 *start;
 28	size_t length;
 29};
 30
 31/* B.2.2 Frame header syntax */
 32
 33/**
 34 * struct v4l2_jpeg_frame_component_spec - frame component-specification
 35 * @component_identifier: C[i]
 36 * @horizontal_sampling_factor: H[i]
 37 * @vertical_sampling_factor: V[i]
 38 * @quantization_table_selector: quantization table destination selector Tq[i]
 39 */
 40struct v4l2_jpeg_frame_component_spec {
 41	u8 component_identifier;
 42	u8 horizontal_sampling_factor;
 43	u8 vertical_sampling_factor;
 44	u8 quantization_table_selector;
 45};
 46
 47/**
 48 * struct v4l2_jpeg_frame_header - JPEG frame header
 49 * @height: Y
 50 * @width: X
 51 * @precision: P
 52 * @num_components: Nf
 53 * @component: component-specification, see v4l2_jpeg_frame_component_spec
 54 * @subsampling: decoded subsampling from component-specification
 55 */
 56struct v4l2_jpeg_frame_header {
 57	u16 height;
 58	u16 width;
 59	u8 precision;
 60	u8 num_components;
 61	struct v4l2_jpeg_frame_component_spec component[V4L2_JPEG_MAX_COMPONENTS];
 62	enum v4l2_jpeg_chroma_subsampling subsampling;
 63};
 64
 65/* B.2.3 Scan header syntax */
 66
 67/**
 68 * struct v4l2_jpeg_scan_component_spec - scan component-specification
 69 * @component_selector: Cs[j]
 70 * @dc_entropy_coding_table_selector: Td[j]
 71 * @ac_entropy_coding_table_selector: Ta[j]
 72 */
 73struct v4l2_jpeg_scan_component_spec {
 74	u8 component_selector;
 75	u8 dc_entropy_coding_table_selector;
 76	u8 ac_entropy_coding_table_selector;
 77};
 78
 79/**
 80 * struct v4l2_jpeg_scan_header - JPEG scan header
 81 * @num_components: Ns
 82 * @component: component-specification, see v4l2_jpeg_scan_component_spec
 83 */
 84struct v4l2_jpeg_scan_header {
 85	u8 num_components;				/* Ns */
 86	struct v4l2_jpeg_scan_component_spec component[V4L2_JPEG_MAX_COMPONENTS];
 87	/* Ss, Se, Ah, and Al are not used by any driver */
 88};
 89
 90/**
 91 * struct v4l2_jpeg_header - parsed JPEG header
 92 * @sof: pointer to frame header and size
 93 * @sos: pointer to scan header and size
 94 * @dht: pointers to huffman tables and sizes
 95 * @dqt: pointers to quantization tables and sizes
 96 * @frame: parsed frame header
 97 * @scan: pointer to parsed scan header, optional
 98 * @quantization_tables: references to four quantization tables, optional
 99 * @huffman_tables: references to four Huffman tables in DC0, DC1, AC0, AC1
100 *                  order, optional
101 * @restart_interval: number of MCU per restart interval, Ri
102 * @ecs_offset: buffer offset in bytes to the entropy coded segment
103 *
104 * When this structure is passed to v4l2_jpeg_parse_header, the optional scan,
105 * quantization_tables, and huffman_tables pointers must be initialized to NULL
106 * or point at valid memory.
107 */
108struct v4l2_jpeg_header {
109	struct v4l2_jpeg_reference sof;
110	struct v4l2_jpeg_reference sos;
111	unsigned int num_dht;
112	struct v4l2_jpeg_reference dht[V4L2_JPEG_MAX_TABLES];
113	unsigned int num_dqt;
114	struct v4l2_jpeg_reference dqt[V4L2_JPEG_MAX_TABLES];
115
116	struct v4l2_jpeg_frame_header frame;
117	struct v4l2_jpeg_scan_header *scan;
118	struct v4l2_jpeg_reference *quantization_tables;
119	struct v4l2_jpeg_reference *huffman_tables;
120	u16 restart_interval;
121	size_t ecs_offset;
122};
123
124int v4l2_jpeg_parse_header(void *buf, size_t len, struct v4l2_jpeg_header *out);
125
126int v4l2_jpeg_parse_frame_header(void *buf, size_t len,
127				 struct v4l2_jpeg_frame_header *frame_header);
128int v4l2_jpeg_parse_scan_header(void *buf, size_t len,
129				struct v4l2_jpeg_scan_header *scan_header);
130int v4l2_jpeg_parse_quantization_tables(void *buf, size_t len, u8 precision,
131					struct v4l2_jpeg_reference *q_tables);
132int v4l2_jpeg_parse_huffman_tables(void *buf, size_t len,
133				   struct v4l2_jpeg_reference *huffman_tables);
134
135#endif