drivers/auxdisplay/hd44780.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * HD44780 Character LCD driver for Linux
  *
  * Copyright (C) 2000-2008, Willy Tarreau <w@1wt.eu>
  * Copyright (C) 2016-2017 Glider bvba
  */

 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
 #include <linux/platform_device.h>
 #include <linux/property.h>
 #include <linux/slab.h>

 #include <misc/charlcd.h>


 enum hd44780_pin {
 	/* Order does matter due to writing to GPIO array subsets! */
 	PIN_DATA0,	/* Optional */
 	PIN_DATA1,	/* Optional */
 	PIN_DATA2,	/* Optional */
 	PIN_DATA3,	/* Optional */
 	PIN_DATA4,
 	PIN_DATA5,
 	PIN_DATA6,
 	PIN_DATA7,
 	PIN_CTRL_RS,
 	PIN_CTRL_RW,	/* Optional */
 	PIN_CTRL_E,
 	PIN_CTRL_BL,   /* Optional */
 	PIN_NUM
 };

 struct hd44780 {
 	struct gpio_desc *pins[PIN_NUM];
 };

 static void hd44780_backlight(struct charlcd *lcd, int on)
 {
 	struct hd44780 *hd = lcd->drvdata;

 	if (hd->pins[PIN_CTRL_BL])
 		gpiod_set_value_cansleep(hd->pins[PIN_CTRL_BL], on);
 }

 static void hd44780_strobe_gpio(struct hd44780 *hd)
 {
 	/* Maintain the data during 20 us before the strobe */
 	udelay(20);

 	gpiod_set_value_cansleep(hd->pins[PIN_CTRL_E], 1);

 	/* Maintain the strobe during 40 us */
 	udelay(40);

 	gpiod_set_value_cansleep(hd->pins[PIN_CTRL_E], 0);
 }

 /* write to an LCD panel register in 8 bit GPIO mode */
 static void hd44780_write_gpio8(struct hd44780 *hd, u8 val, unsigned int rs)
 {
 	DECLARE_BITMAP(values, 10); /* for DATA[0-7], RS, RW */
 	unsigned int n;

 	values[0] = val;
 	__assign_bit(8, values, rs);
 	n = hd->pins[PIN_CTRL_RW] ? 10 : 9;

 	/* Present the data to the port */
 	gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA0], NULL, values);

 	hd44780_strobe_gpio(hd);
 }

 /* write to an LCD panel register in 4 bit GPIO mode */
 static void hd44780_write_gpio4(struct hd44780 *hd, u8 val, unsigned int rs)
 {
 	DECLARE_BITMAP(values, 6); /* for DATA[4-7], RS, RW */
 	unsigned int n;

 	/* High nibble + RS, RW */
 	values[0] = val >> 4;
 	__assign_bit(4, values, rs);
 	n = hd->pins[PIN_CTRL_RW] ? 6 : 5;

 	/* Present the data to the port */
 	gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], NULL, values);

 	hd44780_strobe_gpio(hd);

 	/* Low nibble */
 	values[0] &= ~0x0fUL;
 	values[0] |= val & 0x0f;

 	/* Present the data to the port */
 	gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], NULL, values);

 	hd44780_strobe_gpio(hd);
 }

 /* Send a command to the LCD panel in 8 bit GPIO mode */
 static void hd44780_write_cmd_gpio8(struct charlcd *lcd, int cmd)
 {
 	struct hd44780 *hd = lcd->drvdata;

 	hd44780_write_gpio8(hd, cmd, 0);

 	/* The shortest command takes at least 120 us */
 	udelay(120);
 }

 /* Send data to the LCD panel in 8 bit GPIO mode */
 static void hd44780_write_data_gpio8(struct charlcd *lcd, int data)
 {
 	struct hd44780 *hd = lcd->drvdata;

 	hd44780_write_gpio8(hd, data, 1);

 	/* The shortest data takes at least 45 us */
 	udelay(45);
 }

 static const struct charlcd_ops hd44780_ops_gpio8 = {
 	.write_cmd	= hd44780_write_cmd_gpio8,
 	.write_data	= hd44780_write_data_gpio8,
 	.backlight	= hd44780_backlight,
 };

 /* Send a command to the LCD panel in 4 bit GPIO mode */
 static void hd44780_write_cmd_gpio4(struct charlcd *lcd, int cmd)
 {
 	struct hd44780 *hd = lcd->drvdata;

 	hd44780_write_gpio4(hd, cmd, 0);

 	/* The shortest command takes at least 120 us */
 	udelay(120);
 }

 /* Send 4-bits of a command to the LCD panel in raw 4 bit GPIO mode */
 static void hd44780_write_cmd_raw_gpio4(struct charlcd *lcd, int cmd)
 {
 	DECLARE_BITMAP(values, 6); /* for DATA[4-7], RS, RW */
 	struct hd44780 *hd = lcd->drvdata;
 	unsigned int n;

 	/* Command nibble + RS, RW */
 	values[0] = cmd & 0x0f;
 	n = hd->pins[PIN_CTRL_RW] ? 6 : 5;

 	/* Present the data to the port */
 	gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], NULL, values);

 	hd44780_strobe_gpio(hd);
 }

 /* Send data to the LCD panel in 4 bit GPIO mode */
 static void hd44780_write_data_gpio4(struct charlcd *lcd, int data)
 {
 	struct hd44780 *hd = lcd->drvdata;

 	hd44780_write_gpio4(hd, data, 1);

 	/* The shortest data takes at least 45 us */
 	udelay(45);
 }

 static const struct charlcd_ops hd44780_ops_gpio4 = {
 	.write_cmd	= hd44780_write_cmd_gpio4,
 	.write_cmd_raw4	= hd44780_write_cmd_raw_gpio4,
 	.write_data	= hd44780_write_data_gpio4,
 	.backlight	= hd44780_backlight,
 };

 static int hd44780_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	unsigned int i, base;
 	struct charlcd *lcd;
 	struct hd44780 *hd;
 	int ifwidth, ret;

 	/* Required pins */
 	ifwidth = gpiod_count(dev, "data");
 	if (ifwidth < 0)
 		return ifwidth;

 	switch (ifwidth) {
 	case 4:
 		base = PIN_DATA4;
 		break;
 	case 8:
 		base = PIN_DATA0;
 		break;
 	default:
 		return -EINVAL;
 	}

 	lcd = charlcd_alloc(sizeof(struct hd44780));
 	if (!lcd)
 		return -ENOMEM;

 	hd = lcd->drvdata;

 	for (i = 0; i < ifwidth; i++) {
 		hd->pins[base + i] = devm_gpiod_get_index(dev, "data", i,
 							  GPIOD_OUT_LOW);
 		if (IS_ERR(hd->pins[base + i])) {
 			ret = PTR_ERR(hd->pins[base + i]);
 			goto fail;
 		}
 	}

 	hd->pins[PIN_CTRL_E] = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
 	if (IS_ERR(hd->pins[PIN_CTRL_E])) {
 		ret = PTR_ERR(hd->pins[PIN_CTRL_E]);
 		goto fail;
 	}

 	hd->pins[PIN_CTRL_RS] = devm_gpiod_get(dev, "rs", GPIOD_OUT_HIGH);
 	if (IS_ERR(hd->pins[PIN_CTRL_RS])) {
 		ret = PTR_ERR(hd->pins[PIN_CTRL_RS]);
 		goto fail;
 	}

 	/* Optional pins */
 	hd->pins[PIN_CTRL_RW] = devm_gpiod_get_optional(dev, "rw",
 							GPIOD_OUT_LOW);
 	if (IS_ERR(hd->pins[PIN_CTRL_RW])) {
 		ret = PTR_ERR(hd->pins[PIN_CTRL_RW]);
 		goto fail;
 	}

 	hd->pins[PIN_CTRL_BL] = devm_gpiod_get_optional(dev, "backlight",
 							GPIOD_OUT_LOW);
 	if (IS_ERR(hd->pins[PIN_CTRL_BL])) {
 		ret = PTR_ERR(hd->pins[PIN_CTRL_BL]);
 		goto fail;
 	}

 	/* Required properties */
 	ret = device_property_read_u32(dev, "display-height-chars",
 				       &lcd->height);
 	if (ret)
 		goto fail;
 	ret = device_property_read_u32(dev, "display-width-chars", &lcd->width);
 	if (ret)
 		goto fail;

 	/*
 	 * On displays with more than two rows, the internal buffer width is
 	 * usually equal to the display width
 	 */
 	if (lcd->height > 2)
 		lcd->bwidth = lcd->width;

 	/* Optional properties */
 	device_property_read_u32(dev, "internal-buffer-width", &lcd->bwidth);

 	lcd->ifwidth = ifwidth;
 	lcd->ops = ifwidth == 8 ? &hd44780_ops_gpio8 : &hd44780_ops_gpio4;

 	ret = charlcd_register(lcd);
 	if (ret)
 		goto fail;

 	platform_set_drvdata(pdev, lcd);
 	return 0;

 fail:
 	charlcd_free(lcd);
 	return ret;
 }

 static int hd44780_remove(struct platform_device *pdev)
 {
 	struct charlcd *lcd = platform_get_drvdata(pdev);

 	charlcd_unregister(lcd);

 	charlcd_free(lcd);
 	return 0;
 }

 static const struct of_device_id hd44780_of_match[] = {
 	{ .compatible = "hit,hd44780" },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, hd44780_of_match);

 static struct platform_driver hd44780_driver = {
 	.probe = hd44780_probe,
 	.remove = hd44780_remove,
 	.driver		= {
 		.name	= "hd44780",
 		.of_match_table = hd44780_of_match,
 	},
 };

 module_platform_driver(hd44780_driver);
 MODULE_DESCRIPTION("HD44780 Character LCD driver");
 MODULE_AUTHOR("Geert Uytterhoeven <geert@linux-m68k.org>");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* HD44780 Character LCD driver for Linux
	*
	* Copyright (C) 2000-2008, Willy Tarreau <w@1wt.eu>
	* Copyright (C) 2016-2017 Glider bvba
	*/

	#include <linux/delay.h>
	#include <linux/gpio/consumer.h>
	#include <linux/module.h>
	#include <linux/mod_devicetable.h>
	#include <linux/platform_device.h>
	#include <linux/property.h>
	#include <linux/slab.h>

	#include <misc/charlcd.h>


	enum hd44780_pin {
	/* Order does matter due to writing to GPIO array subsets! */
	PIN_DATA0, /* Optional */
	PIN_DATA1, /* Optional */
	PIN_DATA2, /* Optional */
	PIN_DATA3, /* Optional */
	PIN_DATA4,
	PIN_DATA5,
	PIN_DATA6,
	PIN_DATA7,
	PIN_CTRL_RS,
	PIN_CTRL_RW, /* Optional */
	PIN_CTRL_E,
	PIN_CTRL_BL, /* Optional */
	PIN_NUM
	};

	struct hd44780 {
	struct gpio_desc *pins[PIN_NUM];
	};

	static void hd44780_backlight(struct charlcd *lcd, int on)
	{
	struct hd44780 *hd = lcd->drvdata;

	if (hd->pins[PIN_CTRL_BL])
	gpiod_set_value_cansleep(hd->pins[PIN_CTRL_BL], on);
	}

	static void hd44780_strobe_gpio(struct hd44780 *hd)
	{
	/* Maintain the data during 20 us before the strobe */
	udelay(20);

	gpiod_set_value_cansleep(hd->pins[PIN_CTRL_E], 1);

	/* Maintain the strobe during 40 us */
	udelay(40);

	gpiod_set_value_cansleep(hd->pins[PIN_CTRL_E], 0);
	}

	/* write to an LCD panel register in 8 bit GPIO mode */
	static void hd44780_write_gpio8(struct hd44780 *hd, u8 val, unsigned int rs)
	{
	DECLARE_BITMAP(values, 10); /* for DATA[0-7], RS, RW */
	unsigned int n;

	values[0] = val;
	__assign_bit(8, values, rs);
	n = hd->pins[PIN_CTRL_RW] ? 10 : 9;

	/* Present the data to the port */
	gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA0], NULL, values);

	hd44780_strobe_gpio(hd);
	}

	/* write to an LCD panel register in 4 bit GPIO mode */
	static void hd44780_write_gpio4(struct hd44780 *hd, u8 val, unsigned int rs)
	{
	DECLARE_BITMAP(values, 6); /* for DATA[4-7], RS, RW */
	unsigned int n;

	/* High nibble + RS, RW */
	values[0] = val >> 4;
	__assign_bit(4, values, rs);
	n = hd->pins[PIN_CTRL_RW] ? 6 : 5;

	/* Present the data to the port */
	gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], NULL, values);

	hd44780_strobe_gpio(hd);

	/* Low nibble */
	values[0] &= ~0x0fUL;
	values[0] \|= val & 0x0f;

	/* Present the data to the port */
	gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], NULL, values);

	hd44780_strobe_gpio(hd);
	}

	/* Send a command to the LCD panel in 8 bit GPIO mode */
	static void hd44780_write_cmd_gpio8(struct charlcd *lcd, int cmd)
	{
	struct hd44780 *hd = lcd->drvdata;

	hd44780_write_gpio8(hd, cmd, 0);

	/* The shortest command takes at least 120 us */
	udelay(120);
	}

	/* Send data to the LCD panel in 8 bit GPIO mode */
	static void hd44780_write_data_gpio8(struct charlcd *lcd, int data)
	{
	struct hd44780 *hd = lcd->drvdata;

	hd44780_write_gpio8(hd, data, 1);

	/* The shortest data takes at least 45 us */
	udelay(45);
	}

	static const struct charlcd_ops hd44780_ops_gpio8 = {
	.write_cmd = hd44780_write_cmd_gpio8,
	.write_data = hd44780_write_data_gpio8,
	.backlight = hd44780_backlight,
	};

	/* Send a command to the LCD panel in 4 bit GPIO mode */
	static void hd44780_write_cmd_gpio4(struct charlcd *lcd, int cmd)
	{
	struct hd44780 *hd = lcd->drvdata;

	hd44780_write_gpio4(hd, cmd, 0);

	/* The shortest command takes at least 120 us */
	udelay(120);
	}

	/* Send 4-bits of a command to the LCD panel in raw 4 bit GPIO mode */
	static void hd44780_write_cmd_raw_gpio4(struct charlcd *lcd, int cmd)
	{
	DECLARE_BITMAP(values, 6); /* for DATA[4-7], RS, RW */
	struct hd44780 *hd = lcd->drvdata;
	unsigned int n;

	/* Command nibble + RS, RW */
	values[0] = cmd & 0x0f;
	n = hd->pins[PIN_CTRL_RW] ? 6 : 5;

	/* Present the data to the port */
	gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], NULL, values);

	hd44780_strobe_gpio(hd);
	}

	/* Send data to the LCD panel in 4 bit GPIO mode */
	static void hd44780_write_data_gpio4(struct charlcd *lcd, int data)
	{
	struct hd44780 *hd = lcd->drvdata;

	hd44780_write_gpio4(hd, data, 1);

	/* The shortest data takes at least 45 us */
	udelay(45);
	}

	static const struct charlcd_ops hd44780_ops_gpio4 = {
	.write_cmd = hd44780_write_cmd_gpio4,
	.write_cmd_raw4 = hd44780_write_cmd_raw_gpio4,
	.write_data = hd44780_write_data_gpio4,
	.backlight = hd44780_backlight,
	};

	static int hd44780_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	unsigned int i, base;
	struct charlcd *lcd;
	struct hd44780 *hd;
	int ifwidth, ret;

	/* Required pins */
	ifwidth = gpiod_count(dev, "data");
	if (ifwidth < 0)
	return ifwidth;

	switch (ifwidth) {
	case 4:
	base = PIN_DATA4;
	break;
	case 8:
	base = PIN_DATA0;
	break;
	default:
	return -EINVAL;
	}

	lcd = charlcd_alloc(sizeof(struct hd44780));
	if (!lcd)
	return -ENOMEM;

	hd = lcd->drvdata;

	for (i = 0; i < ifwidth; i++) {
	hd->pins[base + i] = devm_gpiod_get_index(dev, "data", i,
	GPIOD_OUT_LOW);
	if (IS_ERR(hd->pins[base + i])) {
	ret = PTR_ERR(hd->pins[base + i]);
	goto fail;
	}
	}

	hd->pins[PIN_CTRL_E] = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
	if (IS_ERR(hd->pins[PIN_CTRL_E])) {
	ret = PTR_ERR(hd->pins[PIN_CTRL_E]);
	goto fail;
	}

	hd->pins[PIN_CTRL_RS] = devm_gpiod_get(dev, "rs", GPIOD_OUT_HIGH);
	if (IS_ERR(hd->pins[PIN_CTRL_RS])) {
	ret = PTR_ERR(hd->pins[PIN_CTRL_RS]);
	goto fail;
	}

	/* Optional pins */
	hd->pins[PIN_CTRL_RW] = devm_gpiod_get_optional(dev, "rw",
	GPIOD_OUT_LOW);
	if (IS_ERR(hd->pins[PIN_CTRL_RW])) {
	ret = PTR_ERR(hd->pins[PIN_CTRL_RW]);
	goto fail;
	}

	hd->pins[PIN_CTRL_BL] = devm_gpiod_get_optional(dev, "backlight",
	GPIOD_OUT_LOW);
	if (IS_ERR(hd->pins[PIN_CTRL_BL])) {
	ret = PTR_ERR(hd->pins[PIN_CTRL_BL]);
	goto fail;
	}

	/* Required properties */
	ret = device_property_read_u32(dev, "display-height-chars",
	&lcd->height);
	if (ret)
	goto fail;
	ret = device_property_read_u32(dev, "display-width-chars", &lcd->width);
	if (ret)
	goto fail;

	/*
	* On displays with more than two rows, the internal buffer width is
	* usually equal to the display width
	*/
	if (lcd->height > 2)
	lcd->bwidth = lcd->width;

	/* Optional properties */
	device_property_read_u32(dev, "internal-buffer-width", &lcd->bwidth);

	lcd->ifwidth = ifwidth;
	lcd->ops = ifwidth == 8 ? &hd44780_ops_gpio8 : &hd44780_ops_gpio4;

	ret = charlcd_register(lcd);
	if (ret)
	goto fail;

	platform_set_drvdata(pdev, lcd);
	return 0;

	fail:
	charlcd_free(lcd);
	return ret;
	}

	static int hd44780_remove(struct platform_device *pdev)
	{
	struct charlcd *lcd = platform_get_drvdata(pdev);

	charlcd_unregister(lcd);

	charlcd_free(lcd);
	return 0;
	}

	static const struct of_device_id hd44780_of_match[] = {
	{ .compatible = "hit,hd44780" },
	{ /* sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, hd44780_of_match);

	static struct platform_driver hd44780_driver = {
	.probe = hd44780_probe,
	.remove = hd44780_remove,
	.driver = {
	.name = "hd44780",
	.of_match_table = hd44780_of_match,
	},
	};

	module_platform_driver(hd44780_driver);
	MODULE_DESCRIPTION("HD44780 Character LCD driver");
	MODULE_AUTHOR("Geert Uytterhoeven <geert@linux-m68k.org>");
	MODULE_LICENSE("GPL");