1351f683bSMiguel Ojeda // SPDX-License-Identifier: GPL-2.0+ 2d47d8836SGeert Uytterhoeven /* 3d47d8836SGeert Uytterhoeven * HD44780 Character LCD driver for Linux 4d47d8836SGeert Uytterhoeven * 5d47d8836SGeert Uytterhoeven * Copyright (C) 2000-2008, Willy Tarreau <w@1wt.eu> 6d47d8836SGeert Uytterhoeven * Copyright (C) 2016-2017 Glider bvba 7d47d8836SGeert Uytterhoeven */ 8d47d8836SGeert Uytterhoeven 9d47d8836SGeert Uytterhoeven #include <linux/delay.h> 10d47d8836SGeert Uytterhoeven #include <linux/gpio/consumer.h> 11d47d8836SGeert Uytterhoeven #include <linux/module.h> 12ac316725SRandy Dunlap #include <linux/mod_devicetable.h> 13d47d8836SGeert Uytterhoeven #include <linux/platform_device.h> 14d47d8836SGeert Uytterhoeven #include <linux/property.h> 15d47d8836SGeert Uytterhoeven #include <linux/slab.h> 16d47d8836SGeert Uytterhoeven 17d47d8836SGeert Uytterhoeven #include <misc/charlcd.h> 18d47d8836SGeert Uytterhoeven 19d47d8836SGeert Uytterhoeven 20d47d8836SGeert Uytterhoeven enum hd44780_pin { 21d47d8836SGeert Uytterhoeven /* Order does matter due to writing to GPIO array subsets! */ 22d47d8836SGeert Uytterhoeven PIN_DATA0, /* Optional */ 23d47d8836SGeert Uytterhoeven PIN_DATA1, /* Optional */ 24d47d8836SGeert Uytterhoeven PIN_DATA2, /* Optional */ 25d47d8836SGeert Uytterhoeven PIN_DATA3, /* Optional */ 26d47d8836SGeert Uytterhoeven PIN_DATA4, 27d47d8836SGeert Uytterhoeven PIN_DATA5, 28d47d8836SGeert Uytterhoeven PIN_DATA6, 29d47d8836SGeert Uytterhoeven PIN_DATA7, 30d47d8836SGeert Uytterhoeven PIN_CTRL_RS, 31d47d8836SGeert Uytterhoeven PIN_CTRL_RW, /* Optional */ 32d47d8836SGeert Uytterhoeven PIN_CTRL_E, 33d47d8836SGeert Uytterhoeven PIN_CTRL_BL, /* Optional */ 34d47d8836SGeert Uytterhoeven PIN_NUM 35d47d8836SGeert Uytterhoeven }; 36d47d8836SGeert Uytterhoeven 37d47d8836SGeert Uytterhoeven struct hd44780 { 38d47d8836SGeert Uytterhoeven struct gpio_desc *pins[PIN_NUM]; 39d47d8836SGeert Uytterhoeven }; 40d47d8836SGeert Uytterhoeven 41d47d8836SGeert Uytterhoeven static void hd44780_backlight(struct charlcd *lcd, int on) 42d47d8836SGeert Uytterhoeven { 43d47d8836SGeert Uytterhoeven struct hd44780 *hd = lcd->drvdata; 44d47d8836SGeert Uytterhoeven 45d47d8836SGeert Uytterhoeven if (hd->pins[PIN_CTRL_BL]) 46d47d8836SGeert Uytterhoeven gpiod_set_value_cansleep(hd->pins[PIN_CTRL_BL], on); 47d47d8836SGeert Uytterhoeven } 48d47d8836SGeert Uytterhoeven 49d47d8836SGeert Uytterhoeven static void hd44780_strobe_gpio(struct hd44780 *hd) 50d47d8836SGeert Uytterhoeven { 51d47d8836SGeert Uytterhoeven /* Maintain the data during 20 us before the strobe */ 52d47d8836SGeert Uytterhoeven udelay(20); 53d47d8836SGeert Uytterhoeven 54d47d8836SGeert Uytterhoeven gpiod_set_value_cansleep(hd->pins[PIN_CTRL_E], 1); 55d47d8836SGeert Uytterhoeven 56d47d8836SGeert Uytterhoeven /* Maintain the strobe during 40 us */ 57d47d8836SGeert Uytterhoeven udelay(40); 58d47d8836SGeert Uytterhoeven 59d47d8836SGeert Uytterhoeven gpiod_set_value_cansleep(hd->pins[PIN_CTRL_E], 0); 60d47d8836SGeert Uytterhoeven } 61d47d8836SGeert Uytterhoeven 62d47d8836SGeert Uytterhoeven /* write to an LCD panel register in 8 bit GPIO mode */ 63d47d8836SGeert Uytterhoeven static void hd44780_write_gpio8(struct hd44780 *hd, u8 val, unsigned int rs) 64d47d8836SGeert Uytterhoeven { 65b9762bebSJanusz Krzysztofik DECLARE_BITMAP(values, 10); /* for DATA[0-7], RS, RW */ 66b9762bebSJanusz Krzysztofik unsigned int n; 67d47d8836SGeert Uytterhoeven 68b9762bebSJanusz Krzysztofik values[0] = val; 69b9762bebSJanusz Krzysztofik __assign_bit(8, values, rs); 70b9762bebSJanusz Krzysztofik n = hd->pins[PIN_CTRL_RW] ? 10 : 9; 71d47d8836SGeert Uytterhoeven 72d47d8836SGeert Uytterhoeven /* Present the data to the port */ 73*77588c14SJanusz Krzysztofik gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA0], NULL, values); 74d47d8836SGeert Uytterhoeven 75d47d8836SGeert Uytterhoeven hd44780_strobe_gpio(hd); 76d47d8836SGeert Uytterhoeven } 77d47d8836SGeert Uytterhoeven 78d47d8836SGeert Uytterhoeven /* write to an LCD panel register in 4 bit GPIO mode */ 79d47d8836SGeert Uytterhoeven static void hd44780_write_gpio4(struct hd44780 *hd, u8 val, unsigned int rs) 80d47d8836SGeert Uytterhoeven { 81b9762bebSJanusz Krzysztofik DECLARE_BITMAP(values, 6); /* for DATA[4-7], RS, RW */ 82b9762bebSJanusz Krzysztofik unsigned int n; 83d47d8836SGeert Uytterhoeven 84d47d8836SGeert Uytterhoeven /* High nibble + RS, RW */ 85b9762bebSJanusz Krzysztofik values[0] = val >> 4; 86b9762bebSJanusz Krzysztofik __assign_bit(4, values, rs); 87b9762bebSJanusz Krzysztofik n = hd->pins[PIN_CTRL_RW] ? 6 : 5; 88d47d8836SGeert Uytterhoeven 89d47d8836SGeert Uytterhoeven /* Present the data to the port */ 90*77588c14SJanusz Krzysztofik gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], NULL, values); 91d47d8836SGeert Uytterhoeven 92d47d8836SGeert Uytterhoeven hd44780_strobe_gpio(hd); 93d47d8836SGeert Uytterhoeven 94d47d8836SGeert Uytterhoeven /* Low nibble */ 95b9762bebSJanusz Krzysztofik values[0] &= ~0x0fUL; 96b9762bebSJanusz Krzysztofik values[0] |= val & 0x0f; 97d47d8836SGeert Uytterhoeven 98d47d8836SGeert Uytterhoeven /* Present the data to the port */ 99*77588c14SJanusz Krzysztofik gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], NULL, values); 100d47d8836SGeert Uytterhoeven 101d47d8836SGeert Uytterhoeven hd44780_strobe_gpio(hd); 102d47d8836SGeert Uytterhoeven } 103d47d8836SGeert Uytterhoeven 104d47d8836SGeert Uytterhoeven /* Send a command to the LCD panel in 8 bit GPIO mode */ 105d47d8836SGeert Uytterhoeven static void hd44780_write_cmd_gpio8(struct charlcd *lcd, int cmd) 106d47d8836SGeert Uytterhoeven { 107d47d8836SGeert Uytterhoeven struct hd44780 *hd = lcd->drvdata; 108d47d8836SGeert Uytterhoeven 109d47d8836SGeert Uytterhoeven hd44780_write_gpio8(hd, cmd, 0); 110d47d8836SGeert Uytterhoeven 111d47d8836SGeert Uytterhoeven /* The shortest command takes at least 120 us */ 112d47d8836SGeert Uytterhoeven udelay(120); 113d47d8836SGeert Uytterhoeven } 114d47d8836SGeert Uytterhoeven 115d47d8836SGeert Uytterhoeven /* Send data to the LCD panel in 8 bit GPIO mode */ 116d47d8836SGeert Uytterhoeven static void hd44780_write_data_gpio8(struct charlcd *lcd, int data) 117d47d8836SGeert Uytterhoeven { 118d47d8836SGeert Uytterhoeven struct hd44780 *hd = lcd->drvdata; 119d47d8836SGeert Uytterhoeven 120d47d8836SGeert Uytterhoeven hd44780_write_gpio8(hd, data, 1); 121d47d8836SGeert Uytterhoeven 122d47d8836SGeert Uytterhoeven /* The shortest data takes at least 45 us */ 123d47d8836SGeert Uytterhoeven udelay(45); 124d47d8836SGeert Uytterhoeven } 125d47d8836SGeert Uytterhoeven 126d47d8836SGeert Uytterhoeven static const struct charlcd_ops hd44780_ops_gpio8 = { 127d47d8836SGeert Uytterhoeven .write_cmd = hd44780_write_cmd_gpio8, 128d47d8836SGeert Uytterhoeven .write_data = hd44780_write_data_gpio8, 129d47d8836SGeert Uytterhoeven .backlight = hd44780_backlight, 130d47d8836SGeert Uytterhoeven }; 131d47d8836SGeert Uytterhoeven 132d47d8836SGeert Uytterhoeven /* Send a command to the LCD panel in 4 bit GPIO mode */ 133d47d8836SGeert Uytterhoeven static void hd44780_write_cmd_gpio4(struct charlcd *lcd, int cmd) 134d47d8836SGeert Uytterhoeven { 135d47d8836SGeert Uytterhoeven struct hd44780 *hd = lcd->drvdata; 136d47d8836SGeert Uytterhoeven 137d47d8836SGeert Uytterhoeven hd44780_write_gpio4(hd, cmd, 0); 138d47d8836SGeert Uytterhoeven 139d47d8836SGeert Uytterhoeven /* The shortest command takes at least 120 us */ 140d47d8836SGeert Uytterhoeven udelay(120); 141d47d8836SGeert Uytterhoeven } 142d47d8836SGeert Uytterhoeven 143d47d8836SGeert Uytterhoeven /* Send 4-bits of a command to the LCD panel in raw 4 bit GPIO mode */ 144d47d8836SGeert Uytterhoeven static void hd44780_write_cmd_raw_gpio4(struct charlcd *lcd, int cmd) 145d47d8836SGeert Uytterhoeven { 146b9762bebSJanusz Krzysztofik DECLARE_BITMAP(values, 6); /* for DATA[4-7], RS, RW */ 147d47d8836SGeert Uytterhoeven struct hd44780 *hd = lcd->drvdata; 148b9762bebSJanusz Krzysztofik unsigned int n; 149d47d8836SGeert Uytterhoeven 150d47d8836SGeert Uytterhoeven /* Command nibble + RS, RW */ 151b9762bebSJanusz Krzysztofik values[0] = cmd & 0x0f; 152b9762bebSJanusz Krzysztofik n = hd->pins[PIN_CTRL_RW] ? 6 : 5; 153d47d8836SGeert Uytterhoeven 154d47d8836SGeert Uytterhoeven /* Present the data to the port */ 155*77588c14SJanusz Krzysztofik gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], NULL, values); 156d47d8836SGeert Uytterhoeven 157d47d8836SGeert Uytterhoeven hd44780_strobe_gpio(hd); 158d47d8836SGeert Uytterhoeven } 159d47d8836SGeert Uytterhoeven 160d47d8836SGeert Uytterhoeven /* Send data to the LCD panel in 4 bit GPIO mode */ 161d47d8836SGeert Uytterhoeven static void hd44780_write_data_gpio4(struct charlcd *lcd, int data) 162d47d8836SGeert Uytterhoeven { 163d47d8836SGeert Uytterhoeven struct hd44780 *hd = lcd->drvdata; 164d47d8836SGeert Uytterhoeven 165d47d8836SGeert Uytterhoeven hd44780_write_gpio4(hd, data, 1); 166d47d8836SGeert Uytterhoeven 167d47d8836SGeert Uytterhoeven /* The shortest data takes at least 45 us */ 168d47d8836SGeert Uytterhoeven udelay(45); 169d47d8836SGeert Uytterhoeven } 170d47d8836SGeert Uytterhoeven 171d47d8836SGeert Uytterhoeven static const struct charlcd_ops hd44780_ops_gpio4 = { 172d47d8836SGeert Uytterhoeven .write_cmd = hd44780_write_cmd_gpio4, 173d47d8836SGeert Uytterhoeven .write_cmd_raw4 = hd44780_write_cmd_raw_gpio4, 174d47d8836SGeert Uytterhoeven .write_data = hd44780_write_data_gpio4, 175d47d8836SGeert Uytterhoeven .backlight = hd44780_backlight, 176d47d8836SGeert Uytterhoeven }; 177d47d8836SGeert Uytterhoeven 178d47d8836SGeert Uytterhoeven static int hd44780_probe(struct platform_device *pdev) 179d47d8836SGeert Uytterhoeven { 180d47d8836SGeert Uytterhoeven struct device *dev = &pdev->dev; 181d47d8836SGeert Uytterhoeven unsigned int i, base; 182d47d8836SGeert Uytterhoeven struct charlcd *lcd; 183d47d8836SGeert Uytterhoeven struct hd44780 *hd; 184d47d8836SGeert Uytterhoeven int ifwidth, ret; 185d47d8836SGeert Uytterhoeven 186d47d8836SGeert Uytterhoeven /* Required pins */ 187d47d8836SGeert Uytterhoeven ifwidth = gpiod_count(dev, "data"); 188d47d8836SGeert Uytterhoeven if (ifwidth < 0) 189d47d8836SGeert Uytterhoeven return ifwidth; 190d47d8836SGeert Uytterhoeven 191d47d8836SGeert Uytterhoeven switch (ifwidth) { 192d47d8836SGeert Uytterhoeven case 4: 193d47d8836SGeert Uytterhoeven base = PIN_DATA4; 194d47d8836SGeert Uytterhoeven break; 195d47d8836SGeert Uytterhoeven case 8: 196d47d8836SGeert Uytterhoeven base = PIN_DATA0; 197d47d8836SGeert Uytterhoeven break; 198d47d8836SGeert Uytterhoeven default: 199d47d8836SGeert Uytterhoeven return -EINVAL; 200d47d8836SGeert Uytterhoeven } 201d47d8836SGeert Uytterhoeven 202d47d8836SGeert Uytterhoeven lcd = charlcd_alloc(sizeof(struct hd44780)); 203d47d8836SGeert Uytterhoeven if (!lcd) 204d47d8836SGeert Uytterhoeven return -ENOMEM; 205d47d8836SGeert Uytterhoeven 206d47d8836SGeert Uytterhoeven hd = lcd->drvdata; 207d47d8836SGeert Uytterhoeven 208d47d8836SGeert Uytterhoeven for (i = 0; i < ifwidth; i++) { 209d47d8836SGeert Uytterhoeven hd->pins[base + i] = devm_gpiod_get_index(dev, "data", i, 210d47d8836SGeert Uytterhoeven GPIOD_OUT_LOW); 211d47d8836SGeert Uytterhoeven if (IS_ERR(hd->pins[base + i])) { 212d47d8836SGeert Uytterhoeven ret = PTR_ERR(hd->pins[base + i]); 213d47d8836SGeert Uytterhoeven goto fail; 214d47d8836SGeert Uytterhoeven } 215d47d8836SGeert Uytterhoeven } 216d47d8836SGeert Uytterhoeven 217d47d8836SGeert Uytterhoeven hd->pins[PIN_CTRL_E] = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW); 218d47d8836SGeert Uytterhoeven if (IS_ERR(hd->pins[PIN_CTRL_E])) { 219d47d8836SGeert Uytterhoeven ret = PTR_ERR(hd->pins[PIN_CTRL_E]); 220d47d8836SGeert Uytterhoeven goto fail; 221d47d8836SGeert Uytterhoeven } 222d47d8836SGeert Uytterhoeven 223d47d8836SGeert Uytterhoeven hd->pins[PIN_CTRL_RS] = devm_gpiod_get(dev, "rs", GPIOD_OUT_HIGH); 224d47d8836SGeert Uytterhoeven if (IS_ERR(hd->pins[PIN_CTRL_RS])) { 225d47d8836SGeert Uytterhoeven ret = PTR_ERR(hd->pins[PIN_CTRL_RS]); 226d47d8836SGeert Uytterhoeven goto fail; 227d47d8836SGeert Uytterhoeven } 228d47d8836SGeert Uytterhoeven 229d47d8836SGeert Uytterhoeven /* Optional pins */ 230d47d8836SGeert Uytterhoeven hd->pins[PIN_CTRL_RW] = devm_gpiod_get_optional(dev, "rw", 231d47d8836SGeert Uytterhoeven GPIOD_OUT_LOW); 232d47d8836SGeert Uytterhoeven if (IS_ERR(hd->pins[PIN_CTRL_RW])) { 233d47d8836SGeert Uytterhoeven ret = PTR_ERR(hd->pins[PIN_CTRL_RW]); 234d47d8836SGeert Uytterhoeven goto fail; 235d47d8836SGeert Uytterhoeven } 236d47d8836SGeert Uytterhoeven 237d47d8836SGeert Uytterhoeven hd->pins[PIN_CTRL_BL] = devm_gpiod_get_optional(dev, "backlight", 238d47d8836SGeert Uytterhoeven GPIOD_OUT_LOW); 239d47d8836SGeert Uytterhoeven if (IS_ERR(hd->pins[PIN_CTRL_BL])) { 240d47d8836SGeert Uytterhoeven ret = PTR_ERR(hd->pins[PIN_CTRL_BL]); 241d47d8836SGeert Uytterhoeven goto fail; 242d47d8836SGeert Uytterhoeven } 243d47d8836SGeert Uytterhoeven 244d47d8836SGeert Uytterhoeven /* Required properties */ 245c7c3f096SGeert Uytterhoeven ret = device_property_read_u32(dev, "display-height-chars", 246c7c3f096SGeert Uytterhoeven &lcd->height); 247d47d8836SGeert Uytterhoeven if (ret) 248d47d8836SGeert Uytterhoeven goto fail; 249c7c3f096SGeert Uytterhoeven ret = device_property_read_u32(dev, "display-width-chars", &lcd->width); 250d47d8836SGeert Uytterhoeven if (ret) 251d47d8836SGeert Uytterhoeven goto fail; 252d47d8836SGeert Uytterhoeven 253d47d8836SGeert Uytterhoeven /* 254d47d8836SGeert Uytterhoeven * On displays with more than two rows, the internal buffer width is 255d47d8836SGeert Uytterhoeven * usually equal to the display width 256d47d8836SGeert Uytterhoeven */ 257d47d8836SGeert Uytterhoeven if (lcd->height > 2) 258d47d8836SGeert Uytterhoeven lcd->bwidth = lcd->width; 259d47d8836SGeert Uytterhoeven 260d47d8836SGeert Uytterhoeven /* Optional properties */ 261d47d8836SGeert Uytterhoeven device_property_read_u32(dev, "internal-buffer-width", &lcd->bwidth); 262d47d8836SGeert Uytterhoeven 263d47d8836SGeert Uytterhoeven lcd->ifwidth = ifwidth; 264d47d8836SGeert Uytterhoeven lcd->ops = ifwidth == 8 ? &hd44780_ops_gpio8 : &hd44780_ops_gpio4; 265d47d8836SGeert Uytterhoeven 266d47d8836SGeert Uytterhoeven ret = charlcd_register(lcd); 267d47d8836SGeert Uytterhoeven if (ret) 268d47d8836SGeert Uytterhoeven goto fail; 269d47d8836SGeert Uytterhoeven 270d47d8836SGeert Uytterhoeven platform_set_drvdata(pdev, lcd); 271d47d8836SGeert Uytterhoeven return 0; 272d47d8836SGeert Uytterhoeven 273d47d8836SGeert Uytterhoeven fail: 274d47d8836SGeert Uytterhoeven kfree(lcd); 275d47d8836SGeert Uytterhoeven return ret; 276d47d8836SGeert Uytterhoeven } 277d47d8836SGeert Uytterhoeven 278d47d8836SGeert Uytterhoeven static int hd44780_remove(struct platform_device *pdev) 279d47d8836SGeert Uytterhoeven { 280d47d8836SGeert Uytterhoeven struct charlcd *lcd = platform_get_drvdata(pdev); 281d47d8836SGeert Uytterhoeven 282d47d8836SGeert Uytterhoeven charlcd_unregister(lcd); 283d47d8836SGeert Uytterhoeven return 0; 284d47d8836SGeert Uytterhoeven } 285d47d8836SGeert Uytterhoeven 286d47d8836SGeert Uytterhoeven static const struct of_device_id hd44780_of_match[] = { 287d47d8836SGeert Uytterhoeven { .compatible = "hit,hd44780" }, 288d47d8836SGeert Uytterhoeven { /* sentinel */ } 289d47d8836SGeert Uytterhoeven }; 290d47d8836SGeert Uytterhoeven MODULE_DEVICE_TABLE(of, hd44780_of_match); 291d47d8836SGeert Uytterhoeven 292d47d8836SGeert Uytterhoeven static struct platform_driver hd44780_driver = { 293d47d8836SGeert Uytterhoeven .probe = hd44780_probe, 294d47d8836SGeert Uytterhoeven .remove = hd44780_remove, 295d47d8836SGeert Uytterhoeven .driver = { 296d47d8836SGeert Uytterhoeven .name = "hd44780", 297d47d8836SGeert Uytterhoeven .of_match_table = hd44780_of_match, 298d47d8836SGeert Uytterhoeven }, 299d47d8836SGeert Uytterhoeven }; 300d47d8836SGeert Uytterhoeven 301d47d8836SGeert Uytterhoeven module_platform_driver(hd44780_driver); 302d47d8836SGeert Uytterhoeven MODULE_DESCRIPTION("HD44780 Character LCD driver"); 303d47d8836SGeert Uytterhoeven MODULE_AUTHOR("Geert Uytterhoeven <geert@linux-m68k.org>"); 304d47d8836SGeert Uytterhoeven MODULE_LICENSE("GPL"); 305