seg-led-gpio.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Driver for a 7-segment LED display
  4 *
  5 * The decimal point LED present on some devices is currently not
  6 * supported.
  7 *
  8 * Copyright (C) Allied Telesis Labs
  9 */
 10
 11#include <linux/bitmap.h>
 12#include <linux/container_of.h>
 13#include <linux/errno.h>
 14#include <linux/gpio/consumer.h>
 15#include <linux/map_to_7segment.h>
 16#include <linux/mod_devicetable.h>
 17#include <linux/module.h>
 18#include <linux/platform_device.h>
 19#include <linux/types.h>
 20#include <linux/workqueue.h>
 21
 22#include "line-display.h"
 23
 24struct seg_led_priv {
 25	struct linedisp linedisp;
 26	struct delayed_work work;
 27	struct gpio_descs *segment_gpios;
 28};
 29
 30static void seg_led_update(struct work_struct *work)
 31{
 32	struct seg_led_priv *priv = container_of(work, struct seg_led_priv, work.work);
 33	struct linedisp *linedisp = &priv->linedisp;
 34	struct linedisp_map *map = linedisp->map;
 35	DECLARE_BITMAP(values, 8) = { };
 36
 37	bitmap_set_value8(values, map_to_seg7(&map->map.seg7, linedisp->buf[0]), 0);
 38
 39	gpiod_multi_set_value_cansleep(priv->segment_gpios, values);
 40}
 41
 42static int seg_led_linedisp_get_map_type(struct linedisp *linedisp)
 43{
 44	struct seg_led_priv *priv = container_of(linedisp, struct seg_led_priv, linedisp);
 45
 46	INIT_DELAYED_WORK(&priv->work, seg_led_update);
 47	return LINEDISP_MAP_SEG7;
 48}
 49
 50static void seg_led_linedisp_update(struct linedisp *linedisp)
 51{
 52	struct seg_led_priv *priv = container_of(linedisp, struct seg_led_priv, linedisp);
 53
 54	schedule_delayed_work(&priv->work, 0);
 55}
 56
 57static const struct linedisp_ops seg_led_linedisp_ops = {
 58	.get_map_type = seg_led_linedisp_get_map_type,
 59	.update = seg_led_linedisp_update,
 60};
 61
 62static int seg_led_probe(struct platform_device *pdev)
 63{
 64	struct seg_led_priv *priv;
 65	struct device *dev = &pdev->dev;
 66
 67	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 68	if (!priv)
 69		return -ENOMEM;
 70
 71	platform_set_drvdata(pdev, priv);
 72
 73	priv->segment_gpios = devm_gpiod_get_array(dev, "segment", GPIOD_OUT_LOW);
 74	if (IS_ERR(priv->segment_gpios))
 75		return PTR_ERR(priv->segment_gpios);
 76
 77	if (priv->segment_gpios->ndescs < 7 || priv->segment_gpios->ndescs > 8)
 78		return -EINVAL;
 79
 80	return linedisp_register(&priv->linedisp, dev, 1, &seg_led_linedisp_ops);
 81}
 82
 83static void seg_led_remove(struct platform_device *pdev)
 84{
 85	struct seg_led_priv *priv = platform_get_drvdata(pdev);
 86
 87	cancel_delayed_work_sync(&priv->work);
 88	linedisp_unregister(&priv->linedisp);
 89}
 90
 91static const struct of_device_id seg_led_of_match[] = {
 92	{ .compatible = "gpio-7-segment"},
 93	{}
 94};
 95MODULE_DEVICE_TABLE(of, seg_led_of_match);
 96
 97static struct platform_driver seg_led_driver = {
 98	.probe = seg_led_probe,
 99	.remove = seg_led_remove,
100	.driver = {
101		.name = "seg-led-gpio",
102		.of_match_table = seg_led_of_match,
103	},
104};
105module_platform_driver(seg_led_driver);
106
107MODULE_AUTHOR("Chris Packham <chris.packham@alliedtelesis.co.nz>");
108MODULE_DESCRIPTION("7 segment LED driver");
109MODULE_LICENSE("GPL");
110MODULE_IMPORT_NS("LINEDISP");