--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * console driver for LCD2S 4x20 character displays connected through i2c.
+ * The display also has a spi interface, but the driver does not support
+ * this yet.
+ *
+ * This is a driver allowing you to use a LCD2S 4x20 from modtronix
+ * engineering as auxdisplay character device.
+ *
+ * (C) 2019 by Lemonage Software GmbH
+ * Author: Lars Pöschel <poeschel@lemonage.de>
+ * All rights reserved.
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/delay.h>
+
+#include "charlcd.h"
+
+#define LCD2S_CMD_CUR_MOVES_FWD 0x09
+#define LCD2S_CMD_CUR_BLINK_OFF 0x10
+#define LCD2S_CMD_CUR_UL_OFF 0x11
+#define LCD2S_CMD_DISPLAY_OFF 0x12
+#define LCD2S_CMD_CUR_BLINK_ON 0x18
+#define LCD2S_CMD_CUR_UL_ON 0x19
+#define LCD2S_CMD_DISPLAY_ON 0x1a
+#define LCD2S_CMD_BACKLIGHT_OFF 0x20
+#define LCD2S_CMD_BACKLIGHT_ON 0x28
+#define LCD2S_CMD_WRITE 0x80
+#define LCD2S_CMD_MOV_CUR_RIGHT 0x83
+#define LCD2S_CMD_MOV_CUR_LEFT 0x84
+#define LCD2S_CMD_SHIFT_RIGHT 0x85
+#define LCD2S_CMD_SHIFT_LEFT 0x86
+#define LCD2S_CMD_SHIFT_UP 0x87
+#define LCD2S_CMD_SHIFT_DOWN 0x88
+#define LCD2S_CMD_CUR_ADDR 0x89
+#define LCD2S_CMD_CUR_POS 0x8a
+#define LCD2S_CMD_CUR_RESET 0x8b
+#define LCD2S_CMD_CLEAR 0x8c
+#define LCD2S_CMD_DEF_CUSTOM_CHAR 0x92
+#define LCD2S_CMD_READ_STATUS 0xd0
+
+#define LCD2S_CHARACTER_SIZE 8
+
+#define LCD2S_STATUS_BUF_MASK 0x7f
+
+struct lcd2s_data {
+ struct i2c_client *i2c;
+ struct charlcd *charlcd;
+};
+
+static s32 lcd2s_wait_buf_free(const struct i2c_client *client, int count)
+{
+ s32 status;
+
+ status = i2c_smbus_read_byte_data(client, LCD2S_CMD_READ_STATUS);
+ if (status < 0)
+ return status;
+
+ while ((status & LCD2S_STATUS_BUF_MASK) < count) {
+ mdelay(1);
+ status = i2c_smbus_read_byte_data(client,
+ LCD2S_CMD_READ_STATUS);
+ if (status < 0)
+ return status;
+ }
+ return 0;
+}
+
+static int lcd2s_i2c_master_send(const struct i2c_client *client,
+ const char *buf, int count)
+{
+ s32 status;
+
+ status = lcd2s_wait_buf_free(client, count);
+ if (status < 0)
+ return status;
+
+ return i2c_master_send(client, buf, count);
+}
+
+static int lcd2s_i2c_smbus_write_byte(const struct i2c_client *client, u8 value)
+{
+ s32 status;
+
+ status = lcd2s_wait_buf_free(client, 1);
+ if (status < 0)
+ return status;
+
+ return i2c_smbus_write_byte(client, value);
+}
+
+static int lcd2s_print(struct charlcd *lcd, int c)
+{
+ struct lcd2s_data *lcd2s = lcd->drvdata;
+ u8 buf[2] = { LCD2S_CMD_WRITE, c };
+
+ lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf));
+ return 0;
+}
+
+static int lcd2s_gotoxy(struct charlcd *lcd, unsigned int x, unsigned int y)
+{
+ struct lcd2s_data *lcd2s = lcd->drvdata;
+ u8 buf[] = { LCD2S_CMD_CUR_POS, y + 1, x + 1};
+
+ lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf));
+
+ return 0;
+}
+
+static int lcd2s_home(struct charlcd *lcd)
+{
+ struct lcd2s_data *lcd2s = lcd->drvdata;
+
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_RESET);
+ return 0;
+}
+
+static int lcd2s_init_display(struct charlcd *lcd)
+{
+ struct lcd2s_data *lcd2s = lcd->drvdata;
+
+ /* turn everything off, but display on */
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_ON);
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_OFF);
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_MOVES_FWD);
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_OFF);
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_OFF);
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CLEAR);
+
+ return 0;
+}
+
+static int lcd2s_shift_cursor(struct charlcd *lcd, enum charlcd_shift_dir dir)
+{
+ struct lcd2s_data *lcd2s = lcd->drvdata;
+
+ if (dir == CHARLCD_SHIFT_LEFT)
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_MOV_CUR_LEFT);
+ else
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_MOV_CUR_RIGHT);
+
+ return 0;
+}
+
+static int lcd2s_shift_display(struct charlcd *lcd, enum charlcd_shift_dir dir)
+{
+ struct lcd2s_data *lcd2s = lcd->drvdata;
+
+ if (dir == CHARLCD_SHIFT_LEFT)
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_SHIFT_LEFT);
+ else
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_SHIFT_RIGHT);
+
+ return 0;
+}
+
+static void lcd2s_backlight(struct charlcd *lcd, enum charlcd_onoff on)
+{
+ struct lcd2s_data *lcd2s = lcd->drvdata;
+
+ if (on)
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_ON);
+ else
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_BACKLIGHT_OFF);
+}
+
+static int lcd2s_display(struct charlcd *lcd, enum charlcd_onoff on)
+{
+ struct lcd2s_data *lcd2s = lcd->drvdata;
+
+ if (on)
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_ON);
+ else
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_DISPLAY_OFF);
+
+ return 0;
+}
+
+static int lcd2s_cursor(struct charlcd *lcd, enum charlcd_onoff on)
+{
+ struct lcd2s_data *lcd2s = lcd->drvdata;
+
+ if (on)
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_ON);
+ else
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_UL_OFF);
+
+ return 0;
+}
+
+static int lcd2s_blink(struct charlcd *lcd, enum charlcd_onoff on)
+{
+ struct lcd2s_data *lcd2s = lcd->drvdata;
+
+ if (on)
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_ON);
+ else
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CUR_BLINK_OFF);
+
+ return 0;
+}
+
+static int lcd2s_fontsize(struct charlcd *lcd, enum charlcd_fontsize size)
+{
+ return 0;
+}
+
+static int lcd2s_lines(struct charlcd *lcd, enum charlcd_lines lines)
+{
+ return 0;
+}
+
+static int lcd2s_redefine_char(struct charlcd *lcd, char *esc)
+{
+ /* Generator : LGcxxxxx...xx; must have <c> between '0'
+ * and '7', representing the numerical ASCII code of the
+ * redefined character, and <xx...xx> a sequence of 16
+ * hex digits representing 8 bytes for each character.
+ * Most LCDs will only use 5 lower bits of the 7 first
+ * bytes.
+ */
+
+ struct lcd2s_data *lcd2s = lcd->drvdata;
+ u8 buf[LCD2S_CHARACTER_SIZE + 2] = { LCD2S_CMD_DEF_CUSTOM_CHAR };
+ u8 value;
+ int shift, i;
+
+ if (!strchr(esc, ';'))
+ return 0;
+
+ esc++;
+
+ buf[1] = *(esc++) - '0';
+ if (buf[1] > 7)
+ return 1;
+
+ i = 0;
+ shift = 0;
+ value = 0;
+ while (*esc && i < LCD2S_CHARACTER_SIZE + 2) {
+ int half;
+
+ shift ^= 4;
+ half = hex_to_bin(*esc++);
+ if (half < 0)
+ continue;
+
+ value |= half << shift;
+ if (shift == 0) {
+ buf[i++] = value;
+ value = 0;
+ }
+ }
+
+ lcd2s_i2c_master_send(lcd2s->i2c, buf, sizeof(buf));
+ return 1;
+}
+
+static int lcd2s_clear_display(struct charlcd *lcd)
+{
+ struct lcd2s_data *lcd2s = lcd->drvdata;
+
+ /* This implicitly sets cursor to first row and column */
+ lcd2s_i2c_smbus_write_byte(lcd2s->i2c, LCD2S_CMD_CLEAR);
+ return 0;
+}
+
+static const struct charlcd_ops lcd2s_ops = {
+ .print = lcd2s_print,
+ .backlight = lcd2s_backlight,
+ .gotoxy = lcd2s_gotoxy,
+ .home = lcd2s_home,
+ .clear_display = lcd2s_clear_display,
+ .init_display = lcd2s_init_display,
+ .shift_cursor = lcd2s_shift_cursor,
+ .shift_display = lcd2s_shift_display,
+ .display = lcd2s_display,
+ .cursor = lcd2s_cursor,
+ .blink = lcd2s_blink,
+ .fontsize = lcd2s_fontsize,
+ .lines = lcd2s_lines,
+ .redefine_char = lcd2s_redefine_char,
+};
+
+static int lcd2s_i2c_probe(struct i2c_client *i2c,
+ const struct i2c_device_id *id)
+{
+ struct charlcd *lcd;
+ struct lcd2s_data *lcd2s;
+ int err;
+
+ if (!i2c_check_functionality(i2c->adapter,
+ I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
+ I2C_FUNC_SMBUS_WRITE_BLOCK_DATA))
+ return -EIO;
+
+ /* Test, if the display is responding */
+ err = lcd2s_i2c_smbus_write_byte(i2c, LCD2S_CMD_DISPLAY_OFF);
+ if (err < 0)
+ return err;
+
+ lcd = charlcd_alloc();
+ if (!lcd)
+ return -ENOMEM;
+
+ lcd2s = kzalloc(sizeof(struct lcd2s_data), GFP_KERNEL);
+ if (!lcd2s) {
+ err = -ENOMEM;
+ goto fail1;
+ }
+
+ lcd->drvdata = lcd2s;
+ lcd2s->i2c = i2c;
+ lcd2s->charlcd = lcd;
+
+ /* Required properties */
+ err = device_property_read_u32(&i2c->dev, "display-height-chars",
+ &lcd->height);
+ if (err)
+ goto fail2;
+
+ err = device_property_read_u32(&i2c->dev, "display-width-chars",
+ &lcd->width);
+ if (err)
+ goto fail2;
+
+ lcd->ops = &lcd2s_ops;
+
+ err = charlcd_register(lcd2s->charlcd);
+ if (err)
+ goto fail2;
+
+ i2c_set_clientdata(i2c, lcd2s);
+ return 0;
+
+fail2:
+ kfree(lcd2s);
+fail1:
+ kfree(lcd);
+ return err;
+}
+
+static int lcd2s_i2c_remove(struct i2c_client *i2c)
+{
+ struct lcd2s_data *lcd2s = i2c_get_clientdata(i2c);
+
+ kfree(lcd2s->charlcd);
+ charlcd_unregister(lcd2s->charlcd);
+ return 0;
+}
+
+static const struct i2c_device_id lcd2s_i2c_id[] = {
+ { "lcd2s", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, lcd2s_i2c_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id lcd2s_of_table[] = {
+ { .compatible = "modtronix,lcd2s" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, lcd2s_of_table);
+#endif
+
+static struct i2c_driver lcd2s_i2c_driver = {
+ .driver = {
+ .name = "lcd2s",
+ .owner = THIS_MODULE,
+#ifdef CONFIG_OF
+ .of_match_table = of_match_ptr(lcd2s_of_table),
+#endif
+ },
+ .probe = lcd2s_i2c_probe,
+ .remove = lcd2s_i2c_remove,
+ .id_table = lcd2s_i2c_id,
+};
+
+static int __init lcd2s_modinit(void)
+{
+ int ret = 0;
+
+ ret = i2c_add_driver(&lcd2s_i2c_driver);
+ if (ret != 0)
+ pr_err("Failed to register lcd2s driver\n");
+
+ return ret;
+}
+module_init(lcd2s_modinit)
+
+static void __exit lcd2s_exit(void)
+{
+ i2c_del_driver(&lcd2s_i2c_driver);
+}
+module_exit(lcd2s_exit)
+
+MODULE_DESCRIPTION("LCD2S character display driver");
+MODULE_AUTHOR("Lars Poeschel");
+MODULE_LICENSE("GPL");
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