You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
328 lines
7.5 KiB
328 lines
7.5 KiB
/*
|
|
* HD44780 Character LCD driver for Linux
|
|
*
|
|
* Copyright (C) 2000-2008, Willy Tarreau <w@1wt.eu>
|
|
* Copyright (C) 2016-2017 Glider bvba
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation; either version
|
|
* 2 of the License, or (at your option) any later version.
|
|
*/
|
|
|
|
#include <linux/delay.h>
|
|
#include <linux/gpio/consumer.h>
|
|
#include <linux/module.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)
|
|
{
|
|
int values[10]; /* for DATA[0-7], RS, RW */
|
|
unsigned int i, n;
|
|
|
|
for (i = 0; i < 8; i++)
|
|
values[PIN_DATA0 + i] = !!(val & BIT(i));
|
|
values[PIN_CTRL_RS] = rs;
|
|
n = 9;
|
|
if (hd->pins[PIN_CTRL_RW]) {
|
|
values[PIN_CTRL_RW] = 0;
|
|
n++;
|
|
}
|
|
|
|
/* Present the data to the port */
|
|
gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA0], 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)
|
|
{
|
|
int values[10]; /* for DATA[0-7], RS, RW, but DATA[0-3] is unused */
|
|
unsigned int i, n;
|
|
|
|
/* High nibble + RS, RW */
|
|
for (i = 4; i < 8; i++)
|
|
values[PIN_DATA0 + i] = !!(val & BIT(i));
|
|
values[PIN_CTRL_RS] = rs;
|
|
n = 5;
|
|
if (hd->pins[PIN_CTRL_RW]) {
|
|
values[PIN_CTRL_RW] = 0;
|
|
n++;
|
|
}
|
|
|
|
/* Present the data to the port */
|
|
gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4],
|
|
&values[PIN_DATA4]);
|
|
|
|
hd44780_strobe_gpio(hd);
|
|
|
|
/* Low nibble */
|
|
for (i = 0; i < 4; i++)
|
|
values[PIN_DATA4 + i] = !!(val & BIT(i));
|
|
|
|
/* Present the data to the port */
|
|
gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4],
|
|
&values[PIN_DATA4]);
|
|
|
|
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)
|
|
{
|
|
int values[10]; /* for DATA[0-7], RS, RW, but DATA[0-3] is unused */
|
|
struct hd44780 *hd = lcd->drvdata;
|
|
unsigned int i, n;
|
|
|
|
/* Command nibble + RS, RW */
|
|
for (i = 0; i < 4; i++)
|
|
values[PIN_DATA4 + i] = !!(cmd & BIT(i));
|
|
values[PIN_CTRL_RS] = 0;
|
|
n = 5;
|
|
if (hd->pins[PIN_CTRL_RW]) {
|
|
values[PIN_CTRL_RW] = 0;
|
|
n++;
|
|
}
|
|
|
|
/* Present the data to the port */
|
|
gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4],
|
|
&values[PIN_DATA4]);
|
|
|
|
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:
|
|
kfree(lcd);
|
|
return ret;
|
|
}
|
|
|
|
static int hd44780_remove(struct platform_device *pdev)
|
|
{
|
|
struct charlcd *lcd = platform_get_drvdata(pdev);
|
|
|
|
charlcd_unregister(lcd);
|
|
|
|
kfree(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");
|
|
|