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 1775354284SMasahiro Yamada #include "charlcd.h" 18*718e05edSLars Poeschel #include "hd44780_common.h" 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 4166ce7d5cSLars Poeschel static void hd44780_backlight(struct charlcd *lcd, enum charlcd_onoff 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 */ 7377588c14SJanusz 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 */ 9077588c14SJanusz 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 */ 9977588c14SJanusz 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 */ 15577588c14SJanusz 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; 183*718e05edSLars Poeschel struct hd44780_common *hdc; 184d47d8836SGeert Uytterhoeven struct hd44780 *hd; 185*718e05edSLars Poeschel int ifwidth, ret = -ENOMEM; 186d47d8836SGeert Uytterhoeven 187d47d8836SGeert Uytterhoeven /* Required pins */ 188d47d8836SGeert Uytterhoeven ifwidth = gpiod_count(dev, "data"); 189d47d8836SGeert Uytterhoeven if (ifwidth < 0) 190d47d8836SGeert Uytterhoeven return ifwidth; 191d47d8836SGeert Uytterhoeven 192d47d8836SGeert Uytterhoeven switch (ifwidth) { 193d47d8836SGeert Uytterhoeven case 4: 194d47d8836SGeert Uytterhoeven base = PIN_DATA4; 195d47d8836SGeert Uytterhoeven break; 196d47d8836SGeert Uytterhoeven case 8: 197d47d8836SGeert Uytterhoeven base = PIN_DATA0; 198d47d8836SGeert Uytterhoeven break; 199d47d8836SGeert Uytterhoeven default: 200d47d8836SGeert Uytterhoeven return -EINVAL; 201d47d8836SGeert Uytterhoeven } 202d47d8836SGeert Uytterhoeven 203*718e05edSLars Poeschel hdc = hd44780_common_alloc(); 204*718e05edSLars Poeschel if (!hdc) 205d47d8836SGeert Uytterhoeven return -ENOMEM; 206d47d8836SGeert Uytterhoeven 207*718e05edSLars Poeschel lcd = charlcd_alloc(sizeof(struct hd44780)); 208*718e05edSLars Poeschel if (!lcd) 209*718e05edSLars Poeschel goto fail1; 210d47d8836SGeert Uytterhoeven 211*718e05edSLars Poeschel hd = kzalloc(sizeof(struct hd44780), GFP_KERNEL); 212*718e05edSLars Poeschel if (!hd) 213*718e05edSLars Poeschel goto fail2; 214*718e05edSLars Poeschel 215*718e05edSLars Poeschel hdc->hd44780 = hd; 216*718e05edSLars Poeschel lcd->drvdata = hdc; 217d47d8836SGeert Uytterhoeven for (i = 0; i < ifwidth; i++) { 218d47d8836SGeert Uytterhoeven hd->pins[base + i] = devm_gpiod_get_index(dev, "data", i, 219d47d8836SGeert Uytterhoeven GPIOD_OUT_LOW); 220d47d8836SGeert Uytterhoeven if (IS_ERR(hd->pins[base + i])) { 221d47d8836SGeert Uytterhoeven ret = PTR_ERR(hd->pins[base + i]); 222*718e05edSLars Poeschel goto fail3; 223d47d8836SGeert Uytterhoeven } 224d47d8836SGeert Uytterhoeven } 225d47d8836SGeert Uytterhoeven 226d47d8836SGeert Uytterhoeven hd->pins[PIN_CTRL_E] = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW); 227d47d8836SGeert Uytterhoeven if (IS_ERR(hd->pins[PIN_CTRL_E])) { 228d47d8836SGeert Uytterhoeven ret = PTR_ERR(hd->pins[PIN_CTRL_E]); 229*718e05edSLars Poeschel goto fail3; 230d47d8836SGeert Uytterhoeven } 231d47d8836SGeert Uytterhoeven 232d47d8836SGeert Uytterhoeven hd->pins[PIN_CTRL_RS] = devm_gpiod_get(dev, "rs", GPIOD_OUT_HIGH); 233d47d8836SGeert Uytterhoeven if (IS_ERR(hd->pins[PIN_CTRL_RS])) { 234d47d8836SGeert Uytterhoeven ret = PTR_ERR(hd->pins[PIN_CTRL_RS]); 235*718e05edSLars Poeschel goto fail3; 236d47d8836SGeert Uytterhoeven } 237d47d8836SGeert Uytterhoeven 238d47d8836SGeert Uytterhoeven /* Optional pins */ 239d47d8836SGeert Uytterhoeven hd->pins[PIN_CTRL_RW] = devm_gpiod_get_optional(dev, "rw", 240d47d8836SGeert Uytterhoeven GPIOD_OUT_LOW); 241d47d8836SGeert Uytterhoeven if (IS_ERR(hd->pins[PIN_CTRL_RW])) { 242d47d8836SGeert Uytterhoeven ret = PTR_ERR(hd->pins[PIN_CTRL_RW]); 243*718e05edSLars Poeschel goto fail3; 244d47d8836SGeert Uytterhoeven } 245d47d8836SGeert Uytterhoeven 246d47d8836SGeert Uytterhoeven hd->pins[PIN_CTRL_BL] = devm_gpiod_get_optional(dev, "backlight", 247d47d8836SGeert Uytterhoeven GPIOD_OUT_LOW); 248d47d8836SGeert Uytterhoeven if (IS_ERR(hd->pins[PIN_CTRL_BL])) { 249d47d8836SGeert Uytterhoeven ret = PTR_ERR(hd->pins[PIN_CTRL_BL]); 250*718e05edSLars Poeschel goto fail3; 251d47d8836SGeert Uytterhoeven } 252d47d8836SGeert Uytterhoeven 253d47d8836SGeert Uytterhoeven /* Required properties */ 254c7c3f096SGeert Uytterhoeven ret = device_property_read_u32(dev, "display-height-chars", 255c7c3f096SGeert Uytterhoeven &lcd->height); 256d47d8836SGeert Uytterhoeven if (ret) 257*718e05edSLars Poeschel goto fail3; 258c7c3f096SGeert Uytterhoeven ret = device_property_read_u32(dev, "display-width-chars", &lcd->width); 259d47d8836SGeert Uytterhoeven if (ret) 260*718e05edSLars Poeschel goto fail3; 261d47d8836SGeert Uytterhoeven 262d47d8836SGeert Uytterhoeven /* 263d47d8836SGeert Uytterhoeven * On displays with more than two rows, the internal buffer width is 264d47d8836SGeert Uytterhoeven * usually equal to the display width 265d47d8836SGeert Uytterhoeven */ 266d47d8836SGeert Uytterhoeven if (lcd->height > 2) 267d47d8836SGeert Uytterhoeven lcd->bwidth = lcd->width; 268d47d8836SGeert Uytterhoeven 269d47d8836SGeert Uytterhoeven /* Optional properties */ 270d47d8836SGeert Uytterhoeven device_property_read_u32(dev, "internal-buffer-width", &lcd->bwidth); 271d47d8836SGeert Uytterhoeven 272d47d8836SGeert Uytterhoeven lcd->ifwidth = ifwidth; 273d47d8836SGeert Uytterhoeven lcd->ops = ifwidth == 8 ? &hd44780_ops_gpio8 : &hd44780_ops_gpio4; 274d47d8836SGeert Uytterhoeven 275d47d8836SGeert Uytterhoeven ret = charlcd_register(lcd); 276d47d8836SGeert Uytterhoeven if (ret) 277*718e05edSLars Poeschel goto fail3; 278d47d8836SGeert Uytterhoeven 279d47d8836SGeert Uytterhoeven platform_set_drvdata(pdev, lcd); 280d47d8836SGeert Uytterhoeven return 0; 281d47d8836SGeert Uytterhoeven 282*718e05edSLars Poeschel fail3: 283*718e05edSLars Poeschel kfree(hd); 284*718e05edSLars Poeschel fail2: 285*718e05edSLars Poeschel kfree(lcd); 286*718e05edSLars Poeschel fail1: 287*718e05edSLars Poeschel kfree(hdc); 288d47d8836SGeert Uytterhoeven return ret; 289d47d8836SGeert Uytterhoeven } 290d47d8836SGeert Uytterhoeven 291d47d8836SGeert Uytterhoeven static int hd44780_remove(struct platform_device *pdev) 292d47d8836SGeert Uytterhoeven { 293d47d8836SGeert Uytterhoeven struct charlcd *lcd = platform_get_drvdata(pdev); 294d47d8836SGeert Uytterhoeven 295*718e05edSLars Poeschel kfree(lcd->drvdata); 296d47d8836SGeert Uytterhoeven charlcd_unregister(lcd); 29741c8d0adSAndy Shevchenko 298*718e05edSLars Poeschel kfree(lcd); 299d47d8836SGeert Uytterhoeven return 0; 300d47d8836SGeert Uytterhoeven } 301d47d8836SGeert Uytterhoeven 302d47d8836SGeert Uytterhoeven static const struct of_device_id hd44780_of_match[] = { 303d47d8836SGeert Uytterhoeven { .compatible = "hit,hd44780" }, 304d47d8836SGeert Uytterhoeven { /* sentinel */ } 305d47d8836SGeert Uytterhoeven }; 306d47d8836SGeert Uytterhoeven MODULE_DEVICE_TABLE(of, hd44780_of_match); 307d47d8836SGeert Uytterhoeven 308d47d8836SGeert Uytterhoeven static struct platform_driver hd44780_driver = { 309d47d8836SGeert Uytterhoeven .probe = hd44780_probe, 310d47d8836SGeert Uytterhoeven .remove = hd44780_remove, 311d47d8836SGeert Uytterhoeven .driver = { 312d47d8836SGeert Uytterhoeven .name = "hd44780", 313d47d8836SGeert Uytterhoeven .of_match_table = hd44780_of_match, 314d47d8836SGeert Uytterhoeven }, 315d47d8836SGeert Uytterhoeven }; 316d47d8836SGeert Uytterhoeven 317d47d8836SGeert Uytterhoeven module_platform_driver(hd44780_driver); 318d47d8836SGeert Uytterhoeven MODULE_DESCRIPTION("HD44780 Character LCD driver"); 319d47d8836SGeert Uytterhoeven MODULE_AUTHOR("Geert Uytterhoeven <geert@linux-m68k.org>"); 320d47d8836SGeert Uytterhoeven MODULE_LICENSE("GPL"); 321