line-display.h

 1/* SPDX-License-Identifier: GPL-2.0-or-later */
 2/*
 3 * Character line display core support
 4 *
 5 * Copyright (C) 2016 Imagination Technologies
 6 * Author: Paul Burton <paul.burton@mips.com>
 7 *
 8 * Copyright (C) 2021 Glider bv
 9 * Copyright (C) 2025 Jean-François Lessard
10 */
11
12#ifndef _LINEDISP_H
13#define _LINEDISP_H
14
15#include <linux/device.h>
16#include <linux/timer_types.h>
17
18#include <linux/map_to_7segment.h>
19#include <linux/map_to_14segment.h>
20
21struct linedisp;
22
23/**
24 * enum linedisp_map_type - type of the character mapping
25 * @LINEDISP_MAP_SEG7: Map characters to 7 segment display
26 * @LINEDISP_MAP_SEG14: Map characters to 14 segment display
27 */
28enum linedisp_map_type {
29	LINEDISP_MAP_SEG7,
30	LINEDISP_MAP_SEG14,
31};
32
33/**
34 * struct linedisp_map - character mapping
35 * @type: type of the character mapping
36 * @map: conversion character mapping
37 * @size: size of the @map
38 */
39struct linedisp_map {
40	enum linedisp_map_type type;
41	union {
42		struct seg7_conversion_map seg7;
43		struct seg14_conversion_map seg14;
44	} map;
45	unsigned int size;
46};
47
48/**
49 * struct linedisp_ops - character line display operations
50 * @get_map_type: Function called to get the character mapping, if required
51 * @update: Function called to update the display. This must not sleep!
52 */
53struct linedisp_ops {
54	int (*get_map_type)(struct linedisp *linedisp);
55	void (*update)(struct linedisp *linedisp);
56};
57
58/**
59 * struct linedisp - character line display private data structure
60 * @dev: the line display device
61 * @timer: timer used to implement scrolling
62 * @ops: character line display operations
63 * @buf: pointer to the buffer for the string currently displayed
64 * @message: the full message to display or scroll on the display
65 * @num_chars: the number of characters that can be displayed
66 * @message_len: the length of the @message string
67 * @scroll_pos: index of the first character of @message currently displayed
68 * @scroll_rate: scroll interval in jiffies
69 * @id: instance id of this display
70 */
71struct linedisp {
72	struct device dev;
73	struct timer_list timer;
74	const struct linedisp_ops *ops;
75	struct linedisp_map *map;
76	char *buf;
77	char *message;
78	unsigned int num_chars;
79	unsigned int message_len;
80	unsigned int scroll_pos;
81	unsigned int scroll_rate;
82	unsigned int id;
83};
84
85int linedisp_attach(struct linedisp *linedisp, struct device *dev,
86		    unsigned int num_chars, const struct linedisp_ops *ops);
87void linedisp_detach(struct device *dev);
88int linedisp_register(struct linedisp *linedisp, struct device *parent,
89		      unsigned int num_chars, const struct linedisp_ops *ops);
90void linedisp_unregister(struct linedisp *linedisp);
91
92#endif /* LINEDISP_H */