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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/drivers/auxdisplay/line-display.h
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/* SPDX-License-Identifier: GPL-2.0-or-later */

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/*

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 * Character line display core support

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 *

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 * Copyright (C) 2016 Imagination Technologies

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 * Author: Paul Burton <[email protected]>

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 *

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 * Copyright (C) 2021 Glider bv

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 * Copyright (C) 2025 Jean-François Lessard

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 */

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#ifndef _LINEDISP_H

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#define _LINEDISP_H

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#include <linux/device.h>

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#include <linux/timer_types.h>

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#include <linux/map_to_7segment.h>

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#include <linux/map_to_14segment.h>

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struct linedisp;

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/**

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 * enum linedisp_map_type - type of the character mapping

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 * @LINEDISP_MAP_SEG7: Map characters to 7 segment display

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 * @LINEDISP_MAP_SEG14: Map characters to 14 segment display

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 */

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enum linedisp_map_type {

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	LINEDISP_MAP_SEG7,

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	LINEDISP_MAP_SEG14,

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};

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/**

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 * struct linedisp_map - character mapping

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 * @type: type of the character mapping

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 * @map: conversion character mapping

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 * @size: size of the @map

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 */

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struct linedisp_map {

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	enum linedisp_map_type type;

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	union {

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		struct seg7_conversion_map seg7;

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		struct seg14_conversion_map seg14;

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	} map;

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	unsigned int size;

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};

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/**

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 * struct linedisp_ops - character line display operations

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 * @get_map_type: Function called to get the character mapping, if required

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 * @update: Function called to update the display. This must not sleep!

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 */

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struct linedisp_ops {

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	int (*get_map_type)(struct linedisp *linedisp);

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	void (*update)(struct linedisp *linedisp);

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};

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/**

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 * struct linedisp - character line display private data structure

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 * @dev: the line display device

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 * @timer: timer used to implement scrolling

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 * @ops: character line display operations

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 * @buf: pointer to the buffer for the string currently displayed

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 * @message: the full message to display or scroll on the display

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 * @num_chars: the number of characters that can be displayed

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 * @message_len: the length of the @message string

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 * @scroll_pos: index of the first character of @message currently displayed

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 * @scroll_rate: scroll interval in jiffies

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 * @id: instance id of this display

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 */

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struct linedisp {

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	struct device dev;

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	struct timer_list timer;

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	const struct linedisp_ops *ops;

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	struct linedisp_map *map;

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	char *buf;

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	char *message;

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	unsigned int num_chars;

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	unsigned int message_len;

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	unsigned int scroll_pos;

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	unsigned int scroll_rate;

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	unsigned int id;

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};

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int linedisp_attach(struct linedisp *linedisp, struct device *dev,

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		    unsigned int num_chars, const struct linedisp_ops *ops);

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void linedisp_detach(struct device *dev);

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int linedisp_register(struct linedisp *linedisp, struct device *parent,

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		      unsigned int num_chars, const struct linedisp_ops *ops);

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void linedisp_unregister(struct linedisp *linedisp);

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#endif /* LINEDISP_H */

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