diff options
Diffstat (limited to 'drivers/auxdisplay/hd44780.c')
| -rw-r--r-- | drivers/auxdisplay/hd44780.c | 353 |
1 files changed, 353 insertions, 0 deletions
diff --git a/drivers/auxdisplay/hd44780.c b/drivers/auxdisplay/hd44780.c new file mode 100644 index 000000000..d56a5d508 --- /dev/null +++ b/drivers/auxdisplay/hd44780.c @@ -0,0 +1,353 @@ +// 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 "charlcd.h" +#include "hd44780_common.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, enum charlcd_onoff on) +{ + struct hd44780_common *hdc = lcd->drvdata; + struct hd44780 *hd = hdc->hd44780; + + 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 hd44780_common *hdc, int cmd) +{ + struct hd44780 *hd = hdc->hd44780; + + 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 hd44780_common *hdc, int data) +{ + struct hd44780 *hd = hdc->hd44780; + + hd44780_write_gpio8(hd, data, 1); + + /* The shortest data takes at least 45 us */ + udelay(45); +} + +static const struct charlcd_ops hd44780_ops_gpio8 = { + .backlight = hd44780_backlight, + .print = hd44780_common_print, + .gotoxy = hd44780_common_gotoxy, + .home = hd44780_common_home, + .clear_display = hd44780_common_clear_display, + .init_display = hd44780_common_init_display, + .shift_cursor = hd44780_common_shift_cursor, + .shift_display = hd44780_common_shift_display, + .display = hd44780_common_display, + .cursor = hd44780_common_cursor, + .blink = hd44780_common_blink, + .fontsize = hd44780_common_fontsize, + .lines = hd44780_common_lines, + .redefine_char = hd44780_common_redefine_char, +}; + +/* Send a command to the LCD panel in 4 bit GPIO mode */ +static void hd44780_write_cmd_gpio4(struct hd44780_common *hdc, int cmd) +{ + struct hd44780 *hd = hdc->hd44780; + + 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 hd44780_common *hdc, int cmd) +{ + DECLARE_BITMAP(values, 6); /* for DATA[4-7], RS, RW */ + struct hd44780 *hd = hdc->hd44780; + 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 hd44780_common *hdc, int data) +{ + struct hd44780 *hd = hdc->hd44780; + + hd44780_write_gpio4(hd, data, 1); + + /* The shortest data takes at least 45 us */ + udelay(45); +} + +static const struct charlcd_ops hd44780_ops_gpio4 = { + .backlight = hd44780_backlight, + .print = hd44780_common_print, + .gotoxy = hd44780_common_gotoxy, + .home = hd44780_common_home, + .clear_display = hd44780_common_clear_display, + .init_display = hd44780_common_init_display, + .shift_cursor = hd44780_common_shift_cursor, + .shift_display = hd44780_common_shift_display, + .display = hd44780_common_display, + .cursor = hd44780_common_cursor, + .blink = hd44780_common_blink, + .fontsize = hd44780_common_fontsize, + .lines = hd44780_common_lines, + .redefine_char = hd44780_common_redefine_char, +}; + +static int hd44780_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + unsigned int i, base; + struct charlcd *lcd; + struct hd44780_common *hdc; + struct hd44780 *hd; + int ifwidth, ret = -ENOMEM; + + /* 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; + } + + hdc = hd44780_common_alloc(); + if (!hdc) + return -ENOMEM; + + lcd = charlcd_alloc(); + if (!lcd) + goto fail1; + + hd = kzalloc(sizeof(struct hd44780), GFP_KERNEL); + if (!hd) + goto fail2; + + hdc->hd44780 = hd; + lcd->drvdata = hdc; + 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 fail3; + } + } + + 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 fail3; + } + + 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 fail3; + } + + /* 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 fail3; + } + + 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 fail3; + } + + /* Required properties */ + ret = device_property_read_u32(dev, "display-height-chars", + &lcd->height); + if (ret) + goto fail3; + ret = device_property_read_u32(dev, "display-width-chars", &lcd->width); + if (ret) + goto fail3; + + /* + * On displays with more than two rows, the internal buffer width is + * usually equal to the display width + */ + if (lcd->height > 2) + hdc->bwidth = lcd->width; + + /* Optional properties */ + device_property_read_u32(dev, "internal-buffer-width", &hdc->bwidth); + + hdc->ifwidth = ifwidth; + if (ifwidth == 8) { + lcd->ops = &hd44780_ops_gpio8; + hdc->write_data = hd44780_write_data_gpio8; + hdc->write_cmd = hd44780_write_cmd_gpio8; + } else { + lcd->ops = &hd44780_ops_gpio4; + hdc->write_data = hd44780_write_data_gpio4; + hdc->write_cmd = hd44780_write_cmd_gpio4; + hdc->write_cmd_raw4 = hd44780_write_cmd_raw_gpio4; + } + + ret = charlcd_register(lcd); + if (ret) + goto fail3; + + platform_set_drvdata(pdev, lcd); + return 0; + +fail3: + kfree(hd); +fail2: + kfree(lcd); +fail1: + kfree(hdc); + return ret; +} + +static int hd44780_remove(struct platform_device *pdev) +{ + struct charlcd *lcd = platform_get_drvdata(pdev); + struct hd44780_common *hdc = lcd->drvdata; + + charlcd_unregister(lcd); + kfree(hdc->hd44780); + kfree(lcd->drvdata); + + 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"); |