Date:   Mon,  5 Oct 2020 14:12:00 +0200
From:   poeschel@...onage.de
To:     Miguel Ojeda Sandonis <miguel.ojeda.sandonis@...il.com>,
        linux-kernel@...r.kernel.org (open list)
Cc:     Lars Poeschel <poeschel@...onage.de>
Subject: [PATCH v3 32/32] auxdisplay: add a driver for lcd2s character display

From: Lars Poeschel <poeschel@...onage.de>

This driver allows to use a lcd2s 20x4 character display from modtronix
engineering as an auxdisplay charlcd device.

Signed-off-by: Lars Poeschel <poeschel@...onage.de>
---
 drivers/auxdisplay/Kconfig  |  11 +
 drivers/auxdisplay/Makefile |   1 +
 drivers/auxdisplay/lcd2s.c  | 409 ++++++++++++++++++++++++++++++++++++
 3 files changed, 421 insertions(+)
 create mode 100644 drivers/auxdisplay/lcd2s.c

diff --git a/drivers/auxdisplay/Kconfig b/drivers/auxdisplay/Kconfig
index a56171d1a1ba..12054daee7a6 100644
--- a/drivers/auxdisplay/Kconfig
+++ b/drivers/auxdisplay/Kconfig
@@ -173,6 +173,17 @@ config HT16K33
 	  Say yes here to add support for Holtek HT16K33, RAM mapping 16*8
 	  LED controller driver with keyscan.
 
+config LCD2S
+	tristate "lcd2s 20x4 character display over I2C console"
+	depends on I2C
+	select CHARLCD
+	default n
+	help
+	  This is a driver that lets you use the lcd2s 20x4 character display
+	  from modtronix engineering as a console output device. The display
+	  is a simple single color character display. You have to connect it
+	  to an I2C bus.
+
 config ARM_CHARLCD
 	bool "ARM Ltd. Character LCD Driver"
 	depends on PLAT_VERSATILE
diff --git a/drivers/auxdisplay/Makefile b/drivers/auxdisplay/Makefile
index 7e8a8c3eb3c3..307771027c89 100644
--- a/drivers/auxdisplay/Makefile
+++ b/drivers/auxdisplay/Makefile
@@ -12,3 +12,4 @@ obj-$(CONFIG_IMG_ASCII_LCD)	+= img-ascii-lcd.o
 obj-$(CONFIG_HD44780)		+= hd44780.o
 obj-$(CONFIG_HT16K33)		+= ht16k33.o
 obj-$(CONFIG_PARPORT_PANEL)	+= panel.o
+obj-$(CONFIG_LCD2S)		+= lcd2s.o
diff --git a/drivers/auxdisplay/lcd2s.c b/drivers/auxdisplay/lcd2s.c
new file mode 100644
index 000000000000..4b8c597a26fa
--- /dev/null
+++ b/drivers/auxdisplay/lcd2s.c
@@ -0,0 +1,409 @@
+// 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@...onage.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) {
+		shift ^= 4;
+		if (*esc >= '0' && *esc <= '9') {
+			value |= (*esc - '0') << shift;
+		} else if (*esc >= 'A' && *esc <= 'Z') {
+			value |= (*esc - 'A' + 10) << shift;
+		} else if (*esc >= 'a' && *esc <= 'z') {
+			value |= (*esc - 'a' + 10) << shift;
+		} else {
+			esc++;
+			continue;
+		}
+
+		if (shift == 0) {
+			buf[i++] = value;
+			value = 0;
+		}
+
+		esc++;
+	}
+
+	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");
-- 
2.28.0

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