[PATCH v2 7/8] auxdisplay: Add Titanmec TM16xx 7-segment display controllers driver

["Jean-François Lessard" <jefflessard3@gmail.com>]

This patch introduces a new auxiliary display driver for TM16XX family LED controllers and compatible chips:
- Shenzhen Titan Micro Electronics: TM1618, TM1620, TM1628, TM1650
- Fuzhou Fuda Hisi Microelectronics: FD620, FD628, FD650, FD655, FD6551
- Wuxi i-Core Electronics: AiP650, AiP1618, AiP1628
- Princeton Technology: PT6964
- Shenzhen Winrise Technology: HBS658

Known to be successfully tested on:
- H96 Max (I2C, rockchip XY_RK3328)
- Magicsee N5 (I2C, amlogic s905x)
- Tanix TX3 Mini (SPI, amlogic s905w)
- Tanix TX6 (I2C, allwinner h6)
- X92 (SPI)
- X96 Max (SPI, amlogic s905x2)

Acked-by: Paolo Sabatino <paolo.sabatino@gmail.com> # As primary user, integrated tm16xx into Armbian rockchip64
Acked-by: Christian Hewitt <christianshewitt@gmail.com> # As primary user, integrated tm16xx into LibreElec
Tested-by: Boris Gjenero <boris.gjenero@gmail.com> # Tested on X92 (transposed)
Tested-by: Paolo Sabatino <paolo.sabatino@gmail.com> # Tested on H96 Max (XY_RK3328)
Tested-by: Christian Hewitt <christianshewitt@gmail.com> # Tested on X96 Max, Tanix TX3 Mini
Signed-off-by: Jean-François Lessard <jefflessard3@gmail.com>
---
 drivers/auxdisplay/Kconfig  |   18 +
 drivers/auxdisplay/Makefile |    1 +
 drivers/auxdisplay/tm16xx.c | 1305 +++++++++++++++++++++++++++++++++++
 3 files changed, 1324 insertions(+)
 create mode 100644 drivers/auxdisplay/tm16xx.c

diff --git a/drivers/auxdisplay/Kconfig b/drivers/auxdisplay/Kconfig
index bedc6133f9..0195db15f6 100644
--- a/drivers/auxdisplay/Kconfig
+++ b/drivers/auxdisplay/Kconfig
@@ -526,6 +526,24 @@ config SEG_LED_GPIO
 	  This driver can also be built as a module. If so, the module
 	  will be called seg-led-gpio.
 
+config TM16XX
+	tristate "TM16XX-compatible LED controllers display"
+	depends on SPI || I2C
+	select NEW_LEDS
+	select LEDS_CLASS
+	select LEDS_TRIGGERS
+	help
+	  This driver supports the following TM16XX compatible
+	  (I2C and SPI 7-Segment LED display controller) chips:
+	  - Titanmec: TM1618, TM1620, TM1628, TM1650
+	  - Fuda Hisi: FD620, FD628, FD650, FD655, FD6551
+	  - i-Core: AiP650, AiP1618, AiP1628
+	  - Princeton: PT6964
+	  - Winrise: HBS658
+
+	  This driver can also be built as a module. If so, the module
+	  will be called tm16xx.
+
 #
 # Character LCD with non-conforming interface section
 #
diff --git a/drivers/auxdisplay/Makefile b/drivers/auxdisplay/Makefile
index f5c13ed1cd..a2444cfb7a 100644
--- a/drivers/auxdisplay/Makefile
+++ b/drivers/auxdisplay/Makefile
@@ -16,3 +16,4 @@ obj-$(CONFIG_LINEDISP)		+= line-display.o
 obj-$(CONFIG_MAX6959)		+= max6959.o
 obj-$(CONFIG_PARPORT_PANEL)	+= panel.o
 obj-$(CONFIG_SEG_LED_GPIO)	+= seg-led-gpio.o
+obj-$(CONFIG_TM16XX)		+= tm16xx.o
diff --git a/drivers/auxdisplay/tm16xx.c b/drivers/auxdisplay/tm16xx.c
new file mode 100644
index 0000000000..26bb9f8178
--- /dev/null
+++ b/drivers/auxdisplay/tm16xx.c
@@ -0,0 +1,1305 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Auxiliary Display Driver for TM16XX and compatible LED controllers
+ *
+ * Copyright (C) 2024 Jean-François Lessard
+ *
+ * This driver supports various LED controller chips, including TM16XX family,
+ * FD6XX family, PT6964, and HBS658. It provides support for both I2C and SPI interfaces.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/spi/spi.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/leds.h>
+#include <linux/delay.h>
+#include <linux/workqueue.h>
+#include <linux/map_to_7segment.h>
+
+#define TM16XX_DRIVER_NAME "tm16xx"
+#define TM16XX_DEVICE_NAME "display"
+#define DIGIT_SEGMENTS 7
+#define MIN_SEGMENT 0
+#define MAX_SEGMENT 7 /* data stored as 8 bits (u8) */
+
+/* Common bit field definitions */
+// clang-format off
+/* Command type bits (bits 7-6) */
+#define TM16XX_CMD_TYPE_MASK    GENMASK(7, 6)
+#define TM16XX_CMD_MODE         0
+#define TM16XX_CMD_DATA         BIT(6)
+#define TM16XX_CMD_CTRL         BIT(7)
+#define TM16XX_CMD_ADDR         (BIT(7) | BIT(6))
+
+/* Mode command grid settings (bits 1-0) */
+#define TM16XX_MODE_GRID_MASK   GENMASK(1, 0)
+#define TM16XX_MODE_4GRIDS      0
+#define TM16XX_MODE_5GRIDS      BIT(0)
+#define TM16XX_MODE_6GRIDS      BIT(1)
+#define TM16XX_MODE_7GRIDS      (BIT(1) | BIT(0))
+
+/* Data command settings */
+#define TM16XX_DATA_ADDR_MASK   BIT(2)
+#define TM16XX_DATA_ADDR_AUTO   0
+#define TM16XX_DATA_ADDR_FIXED  BIT(2)
+#define TM16XX_DATA_MODE_MASK   GENMASK(1, 0)
+#define TM16XX_DATA_WRITE       0
+#define TM16XX_DATA_READ        BIT(1)
+
+/* Control command settings */
+#define TM16XX_CTRL_ON          BIT(3)
+#define TM16XX_CTRL_BR_MASK     GENMASK(2, 0)
+
+/* TM1618 specific constants */
+#define TM1618_BYTE1_MASK       GENMASK(4, 0)
+#define TM1618_BYTE1_RSHIFT     0
+#define TM1618_BYTE2_MASK       (~TM1618_BYTE1_MASK)
+#define TM1618_BYTE2_RSHIFT     2
+
+/* I2C controller addresses and control settings */
+#define TM1650_CMD_CTRL         0x48
+#define TM1650_CMD_ADDR         0x68
+#define TM1650_CTRL_BR_MASK     GENMASK(6, 4)
+#define TM1650_CTRL_ON          BIT(0)
+#define TM1650_CTRL_SEG_MASK    BIT(3)
+#define TM1650_CTRL_SEG8_MODE   0
+#define TM1650_CTRL_SEG7_MODE   BIT(3)
+
+#define FD655_CMD_CTRL          0x48
+#define FD655_CMD_ADDR          0x66
+#define FD655_CTRL_BR_MASK      GENMASK(6, 5)
+#define FD655_CTRL_ON           BIT(0)
+
+#define FD6551_CMD_CTRL         0x48
+#define FD6551_CTRL_BR_MASK     GENMASK(3, 1)
+#define FD6551_CTRL_ON          BIT(0)
+
+#define TM16XX_CTRL_BRIGHTNESS(enabled, value, prefix) \
+	((enabled) ? \
+	 (FIELD_PREP(prefix##_CTRL_BR_MASK, (value)) | prefix##_CTRL_ON) : \
+	 0)
+// clang-format on
+
+static char *default_value;
+module_param(default_value, charp, 0644);
+MODULE_PARM_DESC(default_value, "Default display value to initialize");
+
+static SEG7_CONVERSION_MAP(map_seg7, MAP_ASCII7SEG_ALPHANUM);
+
+/* Forward declarations */
+struct tm16xx_display;
+
+/**
+ * DOC: struct tm16xx_controller - Controller-specific operations
+ * @max_grids: Maximum number of grids supported by the controller
+ * @max_brightness: Maximum brightness level supported by the controller
+ * @init: Configures the controller mode and brightness
+ * @data: Writes display data to the controller
+ *
+ * This structure holds function pointers for controller-specific operations.
+ */
+struct tm16xx_controller {
+	const u8 max_grids;
+	const u8 max_brightness;
+	int (* const init)(struct tm16xx_display *display);
+	int (* const data)(struct tm16xx_display *display, u8 index, u8 data);
+};
+
+/**
+ * struct tm16xx_led - LED information
+ * @cdev: LED class device
+ * @grid: Grid index of the LED
+ * @segment: Segment index of the LED
+ */
+struct tm16xx_led {
+	struct led_classdev cdev;
+	u8 grid;
+	u8 segment;
+};
+
+/**
+ * struct tm16xx_digit - Digit information
+ * @grid: Grid index of the digit
+ * @value: Current value of the digit
+ */
+struct tm16xx_digit {
+	u8 grid;
+	char value;
+};
+
+/**
+ * struct tm16xx_display - Main driver structure
+ * @dev: Pointer to device structure
+ * @controller: Pointer to controller-specific operations
+ * @client: Union of I2C and SPI client structures
+ * @main_led: LED class device for the entire display
+ * @leds: Array of individual LEDs
+ * @num_leds: Number of LEDs
+ * @digits: Array of digits
+ * @num_digits: Number of digits
+ * @segment_mapping: Segment mapping array
+ * @digit_bitmask: Bitmask for setting digit values
+ * @display_data: Display data buffer
+ * @display_data_len: Length of display data buffer
+ * @lock: Mutex for concurrent access protection
+ * @flush_init: Work structure for brightness update
+ * @flush_display: Work structure for display update
+ * @flush_status: Result of the last flush work
+ * @transpose_display_data: Flag indicating if segments and grids should be transposed when writing data
+ */
+struct tm16xx_display {
+	struct device *dev;
+	const struct tm16xx_controller *controller;
+	union {
+		struct i2c_client *i2c;
+		struct spi_device *spi;
+	} client;
+	struct led_classdev main_led;
+	struct tm16xx_led *leds;
+	int num_leds;
+	struct tm16xx_digit *digits;
+	int num_digits;
+	u8 segment_mapping[DIGIT_SEGMENTS];
+	u8 digit_bitmask;
+	u8 *display_data;
+	size_t display_data_len;
+	struct mutex lock; /* protect shared display state in work functions */
+	struct work_struct flush_init;
+	struct work_struct flush_display;
+	int flush_status;
+	bool transpose_display_data;
+};
+
+/**
+ * tm16xx_i2c_write - Write data to I2C client
+ * @display: Pointer to tm16xx_display structure
+ * @data: Data to write
+ * @len: Length of data
+ *
+ * Return: Number of bytes written or negative error code
+ */
+static int tm16xx_i2c_write(struct tm16xx_display *display, u8 *data, size_t len)
+{
+	dev_dbg(display->dev, "i2c_write %*ph", (char)len, data);
+
+	struct i2c_msg msg = {
+		.addr = data[0] >> 1,
+		.flags = 0,
+		.len = len - 1,
+		.buf = &data[1],
+	};
+	int ret;
+
+	ret = i2c_transfer(display->client.i2c->adapter, &msg, 1);
+	if (ret < 0)
+		return ret;
+
+	return (ret == 1) ? len : -EIO;
+}
+
+/**
+ * tm16xx_spi_write - Write data to SPI client
+ * @display: Pointer to tm16xx_display structure
+ * @data: Data to write
+ * @len: Length of data
+ *
+ * Return: Number of bytes written or negative error code
+ */
+static int tm16xx_spi_write(struct tm16xx_display *display, u8 *data, size_t len)
+{
+	dev_dbg(display->dev, "spi_write %*ph", (char)len, data);
+
+	struct spi_device *spi = display->client.spi;
+
+	return spi_write(spi, data, len);
+}
+
+/* Controller-specific functions */
+static int tm1628_init(struct tm16xx_display *display)
+{
+	const enum led_brightness brightness = display->main_led.brightness;
+	const u8 num_grids = display->transpose_display_data ? DIGIT_SEGMENTS :
+							       display->display_data_len;
+	u8 cmd;
+	int ret;
+
+	/* Set mode command based on grid count */
+	cmd = TM16XX_CMD_MODE;
+	if (num_grids <= 4)
+		cmd |= TM16XX_MODE_4GRIDS;
+	else if (num_grids == 5)
+		cmd |= TM16XX_MODE_5GRIDS;
+	else if (num_grids == 6)
+		cmd |= TM16XX_MODE_6GRIDS;
+	else
+		cmd |= TM16XX_MODE_7GRIDS;
+
+	ret = tm16xx_spi_write(display, &cmd, 1);
+	if (ret < 0)
+		return ret;
+
+	/* Set data command */
+	cmd = TM16XX_CMD_DATA | TM16XX_DATA_ADDR_AUTO | TM16XX_DATA_WRITE;
+	ret = tm16xx_spi_write(display, &cmd, 1);
+	if (ret < 0)
+		return ret;
+
+	/* Set control command with brightness */
+	cmd = TM16XX_CMD_CTRL |
+	      TM16XX_CTRL_BRIGHTNESS(brightness, brightness - 1, TM16XX);
+	ret = tm16xx_spi_write(display, &cmd, 1);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int tm1618_data(struct tm16xx_display *display, u8 index, u8 data)
+{
+	u8 cmds[3];
+
+	cmds[0] = TM16XX_CMD_ADDR + index * 2;
+	cmds[1] = (data & TM1618_BYTE1_MASK) >> TM1618_BYTE1_RSHIFT;
+	cmds[2] = (data & TM1618_BYTE2_MASK) >> TM1618_BYTE2_RSHIFT;
+
+	return tm16xx_spi_write(display, cmds, ARRAY_SIZE(cmds));
+}
+
+static int tm1628_data(struct tm16xx_display *display, u8 index, u8 data)
+{
+	u8 cmds[3];
+
+	cmds[0] = TM16XX_CMD_ADDR + index * 2;
+	cmds[1] = data; // SEG 1 to 8
+	cmds[2] = 0; // SEG 9 to 14
+
+	return tm16xx_spi_write(display, cmds, ARRAY_SIZE(cmds));
+}
+
+static int tm1650_init(struct tm16xx_display *display)
+{
+	u8 cmds[2];
+	const enum led_brightness brightness = display->main_led.brightness;
+
+	cmds[0] = TM1650_CMD_CTRL;
+	cmds[1] = TM16XX_CTRL_BRIGHTNESS(brightness, brightness, TM1650) |
+		  TM1650_CTRL_SEG8_MODE;
+
+	return tm16xx_i2c_write(display, cmds, ARRAY_SIZE(cmds));
+}
+
+static int tm1650_data(struct tm16xx_display *display, u8 index, u8 data)
+{
+	u8 cmds[2];
+
+	cmds[0] = TM1650_CMD_ADDR + index * 2;
+	cmds[1] = data; // SEG 1 to 8
+
+	return tm16xx_i2c_write(display, cmds, ARRAY_SIZE(cmds));
+}
+
+static int fd655_init(struct tm16xx_display *display)
+{
+	u8 cmds[2];
+	const enum led_brightness brightness = display->main_led.brightness;
+
+	cmds[0] = FD655_CMD_CTRL;
+	cmds[1] = TM16XX_CTRL_BRIGHTNESS(brightness, brightness % 3, FD655);
+
+	return tm16xx_i2c_write(display, cmds, ARRAY_SIZE(cmds));
+}
+
+static int fd655_data(struct tm16xx_display *display, u8 index, u8 data)
+{
+	u8 cmds[2];
+
+	cmds[0] = FD655_CMD_ADDR + index * 2;
+	cmds[1] = data; // SEG 1 to 8
+
+	return tm16xx_i2c_write(display, cmds, ARRAY_SIZE(cmds));
+}
+
+static int fd6551_init(struct tm16xx_display *display)
+{
+	u8 cmds[2];
+	const enum led_brightness brightness = display->main_led.brightness;
+
+	cmds[0] = FD6551_CMD_CTRL;
+	cmds[1] = TM16XX_CTRL_BRIGHTNESS(brightness, ~(brightness - 1), FD6551);
+
+	return tm16xx_i2c_write(display, cmds, ARRAY_SIZE(cmds));
+}
+
+static void hbs658_swap_nibbles(u8 *data, size_t len)
+{
+	for (size_t i = 0; i < len; i++)
+		data[i] = (data[i] << 4) | (data[i] >> 4);
+}
+
+static int hbs658_init(struct tm16xx_display *display)
+{
+	const enum led_brightness brightness = display->main_led.brightness;
+	u8 cmd;
+	int ret;
+
+	/* Set data command */
+	cmd = TM16XX_CMD_DATA | TM16XX_DATA_ADDR_AUTO | TM16XX_DATA_WRITE;
+	hbs658_swap_nibbles(&cmd, 1);
+	ret = tm16xx_spi_write(display, &cmd, 1);
+	if (ret < 0)
+		return ret;
+
+	/* Set control command with brightness */
+	cmd = TM16XX_CMD_CTRL |
+	      TM16XX_CTRL_BRIGHTNESS(brightness, brightness - 1, TM16XX);
+	hbs658_swap_nibbles(&cmd, 1);
+	ret = tm16xx_spi_write(display, &cmd, 1);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int hbs658_data(struct tm16xx_display *display, u8 index, u8 data)
+{
+	u8 cmds[2];
+
+	cmds[0] = TM16XX_CMD_ADDR + index * 2;
+	cmds[1] = data;
+
+	hbs658_swap_nibbles(cmds, ARRAY_SIZE(cmds));
+	return tm16xx_spi_write(display, cmds, ARRAY_SIZE(cmds));
+}
+
+/* Controller definitions */
+static const struct tm16xx_controller tm1618_controller = {
+	.max_grids = 7,
+	.max_brightness = 8,
+	.init = tm1628_init,
+	.data = tm1618_data,
+};
+
+static const struct tm16xx_controller tm1628_controller = {
+	.max_grids = 7,
+	.max_brightness = 8,
+	.init = tm1628_init,
+	.data = tm1628_data,
+};
+
+static const struct tm16xx_controller tm1650_controller = {
+	.max_grids = 4,
+	.max_brightness = 8,
+	.init = tm1650_init,
+	.data = tm1650_data,
+};
+
+static const struct tm16xx_controller fd655_controller = {
+	.max_grids = 5,
+	.max_brightness = 3,
+	.init = fd655_init,
+	.data = fd655_data,
+};
+
+static const struct tm16xx_controller fd6551_controller = {
+	.max_grids = 5,
+	.max_brightness = 8,
+	.init = fd6551_init,
+	.data = fd655_data,
+};
+
+static const struct tm16xx_controller hbs658_controller = {
+	.max_grids = 5,
+	.max_brightness = 8,
+	.init = hbs658_init,
+	.data = hbs658_data,
+};
+
+/**
+ * tm16xx_ascii_to_segments - Convert ASCII character to segment pattern
+ * @display: Pointer to tm16xx_display structure
+ * @c: ASCII character to convert
+ *
+ * Return: Segment pattern for the given ASCII character
+ */
+static u8 tm16xx_ascii_to_segments(struct tm16xx_display *display, char c)
+{
+	u8 standard_segments, mapped_segments = 0;
+	int i;
+
+	standard_segments = map_to_seg7(&map_seg7, c);
+
+	for (i = 0; i < DIGIT_SEGMENTS; i++) {
+		if (standard_segments & BIT(i))
+			mapped_segments |= BIT(display->segment_mapping[i]);
+	}
+
+	return mapped_segments;
+}
+
+/**
+ * tm16xx_display_flush_init - Work function to update controller configuration (mode and brightness)
+ * @work: Pointer to work_struct
+ */
+static void tm16xx_display_flush_init(struct work_struct *work)
+{
+	struct tm16xx_display *display =
+		container_of(work, struct tm16xx_display, flush_init);
+	int ret;
+
+	if (display->controller->init) {
+		mutex_lock(&display->lock);
+		ret = display->controller->init(display);
+		display->flush_status = ret;
+		mutex_unlock(&display->lock);
+		if (ret < 0)
+			dev_err(display->dev, "Failed to set brightness: %d\n", ret);
+	}
+}
+
+/**
+ * tm16xx_display_flush_data - Work function to update display data
+ * @work: Pointer to work_struct
+ */
+static void tm16xx_display_flush_data(struct work_struct *work)
+{
+	struct tm16xx_display *display =
+		container_of(work, struct tm16xx_display, flush_display);
+	int i, ret = 0;
+
+	mutex_lock(&display->lock);
+
+	if (display->controller->data) {
+		for (i = 0; i < display->display_data_len; i++) {
+			ret = display->controller->data(display, i,
+							display->display_data[i]);
+			if (ret < 0) {
+				dev_err(display->dev,
+					"Failed to write display data: %d\n", ret);
+				break;
+			}
+		}
+	}
+
+	display->flush_status = ret;
+	mutex_unlock(&display->lock);
+}
+
+/**
+ * tm16xx_display_flush_data_transposed - Transposed flush work function
+ * @work: Pointer to work_struct
+ */
+static void tm16xx_display_flush_data_transposed(struct work_struct *work)
+{
+	struct tm16xx_display *display =
+		container_of(work, struct tm16xx_display, flush_display);
+	int i, j, ret = 0;
+	u8 transposed_data;
+
+	mutex_lock(&display->lock);
+
+	if (display->controller->data) {
+		/* Write operations based on number of segments */
+		for (i = MIN_SEGMENT; i <= MAX_SEGMENT; i++) {
+			/* Gather bits from each grid for this segment */
+			transposed_data = 0;
+			for (j = 0; j < display->display_data_len; j++) {
+				if (display->display_data[j] & BIT(i))
+					transposed_data |= BIT(MAX_SEGMENT - j);
+			}
+
+			ret = display->controller->data(display, i, transposed_data);
+			if (ret < 0) {
+				dev_err(display->dev,
+					"Failed to write transposed data: %d\n", ret);
+				break;
+			}
+		}
+	}
+
+	display->flush_status = ret;
+	mutex_unlock(&display->lock);
+}
+
+/**
+ * tm16xx_display_remove - Remove the display
+ * @display: Pointer to tm16xx_display structure
+ */
+static void tm16xx_display_remove(struct tm16xx_display *display)
+{
+	memset(display->display_data, 0x00, display->display_data_len);
+	schedule_work(&display->flush_display);
+	flush_work(&display->flush_display);
+
+	display->main_led.brightness = LED_OFF;
+	schedule_work(&display->flush_init);
+	flush_work(&display->flush_init);
+
+	dev_info(display->dev, "Display turned off\n");
+}
+
+/**
+ * tm16xx_brightness_set - Set brightness of the display
+ * @led_cdev: Pointer to led_classdev
+ * @brightness: Brightness value to set
+ */
+static void tm16xx_brightness_set(struct led_classdev *led_cdev,
+				  enum led_brightness brightness)
+{
+	struct tm16xx_display *display = dev_get_drvdata(led_cdev->dev->parent);
+
+	led_cdev->brightness = brightness;
+	schedule_work(&display->flush_init);
+}
+
+/**
+ * tm16xx_led_set - Set state of an individual LED
+ * @led_cdev: Pointer to led_classdev
+ * @value: Value to set (on/off)
+ */
+static void tm16xx_led_set(struct led_classdev *led_cdev, enum led_brightness value)
+{
+	struct tm16xx_led *led = container_of(led_cdev, struct tm16xx_led, cdev);
+	struct tm16xx_display *display = dev_get_drvdata(led_cdev->dev->parent);
+
+	if (value)
+		display->display_data[led->grid] |= (1 << led->segment);
+	else
+		display->display_data[led->grid] &= ~(1 << led->segment);
+
+	schedule_work(&display->flush_display);
+}
+
+/**
+ * tm16xx_value_show - Show current display value
+ * @dev: Pointer to device structure
+ * @attr: Pointer to device attribute structure
+ * @buf: Buffer to write the display value
+ *
+ * Return: Number of bytes written to buffer
+ */
+static ssize_t tm16xx_value_show(struct device *dev, struct device_attribute *attr,
+				 char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct tm16xx_display *display = dev_get_drvdata(led_cdev->dev->parent);
+	int i;
+
+	for (i = 0; i < display->num_digits && i < PAGE_SIZE - 1; i++)
+		buf[i] = display->digits[i].value;
+
+	buf[i++] = '\n';
+
+	return i;
+}
+
+/**
+ * tm16xx_value_store - Store new display value
+ * @dev: Pointer to device structure
+ * @attr: Pointer to device attribute structure
+ * @buf: Buffer containing the new display value
+ * @count: Number of bytes in buffer
+ *
+ * Return: Number of bytes written or negative error code
+ */
+static ssize_t tm16xx_value_store(struct device *dev, struct device_attribute *attr,
+				  const char *buf, size_t count)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct tm16xx_display *display = dev_get_drvdata(led_cdev->dev->parent);
+	struct tm16xx_digit *digit;
+	int i;
+	u8 data;
+
+	for (i = 0; i < display->num_digits; i++) {
+		digit = &display->digits[i];
+
+		if (i < count && buf[i] != '\n') {
+			digit->value = buf[i];
+			data = tm16xx_ascii_to_segments(display, digit->value);
+		} else {
+			digit->value = 0;
+			data = 0;
+		}
+
+		display->display_data[digit->grid] =
+			(display->display_data[digit->grid] & ~display->digit_bitmask) |
+			(data & display->digit_bitmask);
+	}
+
+	schedule_work(&display->flush_display);
+
+	return count;
+}
+
+/**
+ * tm16xx_num_digits_show - Show the number of digits in the display
+ * @dev: The device struct
+ * @attr: The device_attribute struct
+ * @buf: The output buffer
+ *
+ * This function returns the number of digits in the display.
+ *
+ * Return: Number of bytes written to buf
+ */
+static ssize_t tm16xx_num_digits_show(struct device *dev, struct device_attribute *attr,
+				      char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct tm16xx_display *display = dev_get_drvdata(led_cdev->dev->parent);
+
+	return sprintf(buf, "%d\n", display->num_digits);
+}
+
+static int tm16xx_parse_int_array(const char *buf, int **array)
+{
+	int *values, value, count = 0, len;
+	const char *ptr = buf;
+
+	while (sscanf(ptr, "%d %n", &value, &len) == 1) {
+		count++;
+		ptr += len;
+	}
+
+	if (count == 0) {
+		*array = NULL;
+		return 0;
+	}
+
+	values = kmalloc(count * sizeof(*values), GFP_KERNEL);
+	if (!values)
+		return -ENOMEM;
+
+	ptr = buf;
+	count = 0;
+	while (sscanf(ptr, "%d %n", &value, &len) == 1) {
+		values[count++] = value;
+		ptr += len;
+	}
+
+	*array = values;
+	return count;
+}
+
+/**
+ * tm16xx_segments_show - Show the current segment mapping
+ * @dev: The device struct
+ * @attr: The device_attribute struct
+ * @buf: The output buffer
+ *
+ * This function returns the current segment mapping of the display.
+ *
+ * Return: Number of bytes written to buf
+ */
+static ssize_t tm16xx_segments_show(struct device *dev, struct device_attribute *attr,
+				    char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct tm16xx_display *display = dev_get_drvdata(led_cdev->dev->parent);
+	int i, count = 0;
+
+	for (i = 0; i < DIGIT_SEGMENTS; i++)
+		count += sprintf(buf + count, "%d ", display->segment_mapping[i]);
+
+	count += sprintf(buf + count, "\n");
+
+	return count;
+}
+
+/**
+ * tm16xx_segments_store - Set a new segment mapping
+ * @dev: The device struct
+ * @attr: The device_attribute struct
+ * @buf: The input buffer
+ * @count: Number of bytes in buf
+ *
+ * This function sets a new segment mapping for the display.
+ * It validates that each value is within the valid range, and that
+ * the number of received values matches the number of segments.
+ *
+ * Return: count on success, negative errno on failure
+ */
+static ssize_t tm16xx_segments_store(struct device *dev, struct device_attribute *attr,
+				     const char *buf, size_t count)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct tm16xx_display *display = dev_get_drvdata(led_cdev->dev->parent);
+	int *array, ret, i;
+
+	ret = tm16xx_parse_int_array(buf, &array);
+	if (ret < 0)
+		return ret;
+
+	if (ret != DIGIT_SEGMENTS) {
+		kfree(array);
+		return -EINVAL;
+	}
+
+	for (i = 0; i < DIGIT_SEGMENTS; i++) {
+		if (array[i] < MIN_SEGMENT || array[i] > MAX_SEGMENT) {
+			kfree(array);
+			return -EINVAL;
+		}
+	}
+
+	display->digit_bitmask = 0;
+	for (i = 0; i < DIGIT_SEGMENTS; i++) {
+		display->segment_mapping[i] = (u8)array[i];
+		display->digit_bitmask |= BIT(display->segment_mapping[i]);
+	}
+
+	kfree(array);
+	return count;
+}
+
+/**
+ * tm16xx_digits_show - Show the current digit ordering
+ * @dev: The device struct
+ * @attr: The device_attribute struct
+ * @buf: The output buffer
+ *
+ * This function returns the current ordering of digits in the display.
+ *
+ * Return: Number of bytes written to buf
+ */
+static ssize_t tm16xx_digits_show(struct device *dev, struct device_attribute *attr,
+				  char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct tm16xx_display *display = dev_get_drvdata(led_cdev->dev->parent);
+	int i, count = 0;
+
+	for (i = 0; i < display->num_digits; i++)
+		count += sprintf(buf + count, "%d ", display->digits[i].grid);
+
+	count += sprintf(buf + count, "\n");
+
+	return count;
+}
+
+/**
+ * tm16xx_digits_store - Set a new digit ordering
+ * @dev: The device struct
+ * @attr: The device_attribute struct
+ * @buf: The input buffer
+ * @count: Number of bytes in buf
+ *
+ * This function sets a new ordering of digits for the display.
+ * It validates that all values match the original digit grid indexes,
+ * and that the number of received values matches the number of digits.
+ *
+ * Return: count on success, negative errno on failure
+ */
+static ssize_t tm16xx_digits_store(struct device *dev, struct device_attribute *attr,
+				   const char *buf, size_t count)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct tm16xx_display *display = dev_get_drvdata(led_cdev->dev->parent);
+	int *array, ret, i, j;
+	bool found;
+
+	ret = tm16xx_parse_int_array(buf, &array);
+	if (ret < 0)
+		return ret;
+
+	if (ret != display->num_digits) {
+		kfree(array);
+		return -EINVAL;
+	}
+
+	for (i = 0; i < display->num_digits; i++) {
+		found = false;
+
+		for (j = 0; j < display->num_digits; j++) {
+			if (display->digits[i].grid == array[j]) {
+				found = true;
+				break;
+			}
+		}
+
+		if (!found) {
+			kfree(array);
+			return -EINVAL;
+		}
+	}
+
+	for (i = 0; i < display->num_digits; i++)
+		display->digits[i].grid = (u8)array[i];
+
+	kfree(array);
+	return count;
+}
+
+/**
+ * tm16xx_map_seg7_show - Show the current 7-segment character map
+ * @dev: The device struct
+ * @attr: The device_attribute struct
+ * @buf: The output buffer
+ *
+ * This function returns the current 7-segment character map.
+ *
+ * Return: Number of bytes written to buf
+ */
+static ssize_t tm16xx_map_seg7_show(struct device *dev, struct device_attribute *attr,
+				    char *buf)
+{
+	memcpy(buf, &map_seg7, sizeof(map_seg7));
+	return sizeof(map_seg7);
+}
+
+/**
+ * tm16xx_map_seg7_store - Set a new 7-segment character map
+ * @dev: The device struct
+ * @attr: The device_attribute struct
+ * @buf: The input buffer
+ * @cnt: Number of bytes in buf
+ *
+ * This function sets a new 7-segment character map.
+ *
+ * Return: cnt on success, negative errno on failure
+ */
+static ssize_t tm16xx_map_seg7_store(struct device *dev, struct device_attribute *attr,
+				     const char *buf, size_t cnt)
+{
+	if (cnt != sizeof(map_seg7))
+		return -EINVAL;
+	memcpy(&map_seg7, buf, cnt);
+	return cnt;
+}
+
+// clang-format off
+static DEVICE_ATTR(value, 0644, tm16xx_value_show, tm16xx_value_store);
+static DEVICE_ATTR(num_digits, 0444, tm16xx_num_digits_show, NULL);
+static DEVICE_ATTR(segments, 0644, tm16xx_segments_show, tm16xx_segments_store);
+static DEVICE_ATTR(digits, 0644, tm16xx_digits_show, tm16xx_digits_store);
+static DEVICE_ATTR(map_seg7, 0644, tm16xx_map_seg7_show, tm16xx_map_seg7_store);
+
+static struct attribute *tm16xx_main_led_attrs[] = {
+	&dev_attr_value.attr,
+	&dev_attr_num_digits.attr,
+	&dev_attr_segments.attr,
+	&dev_attr_digits.attr,
+	&dev_attr_map_seg7.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(tm16xx_main_led);
+// clang-format on
+
+/**
+ * tm16xx_display_init - Initialize the display
+ * @display: Pointer to tm16xx_display structure
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+static int tm16xx_display_init(struct tm16xx_display *display)
+{
+	schedule_work(&display->flush_init);
+	flush_work(&display->flush_init);
+	if (display->flush_status < 0)
+		return display->flush_status;
+
+	if (default_value && strlen(default_value) > 0) {
+		tm16xx_value_store(display->main_led.dev, NULL, default_value,
+				   strlen(default_value));
+	} else {
+		memset(display->display_data, 0xFF, display->display_data_len);
+		schedule_work(&display->flush_display);
+		flush_work(&display->flush_display);
+		memset(display->display_data, 0x00, display->display_data_len);
+		if (display->flush_status < 0)
+			return display->flush_status;
+	}
+
+	return 0;
+}
+
+/**
+ * tm16xx_parse_dt - Parse device tree data
+ * @dev: Pointer to device structure
+ * @display: Pointer to tm16xx_display structure
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+static int tm16xx_parse_dt(struct device *dev, struct tm16xx_display *display)
+{
+	struct fwnode_handle *child;
+	int ret, i, max_grid = 0;
+	u8 *digits;
+
+	display->transpose_display_data =
+		device_property_read_bool(dev, "titanmec,transposed");
+
+	ret = device_property_count_u8(dev, "titanmec,digits");
+	if (ret < 0) {
+		dev_err(dev, "Failed to count 'titanmec,digits' property: %d\n", ret);
+		return ret;
+	}
+
+	display->num_digits = ret;
+	dev_dbg(dev, "Number of digits: %d\n", display->num_digits);
+
+	digits = devm_kcalloc(dev, display->num_digits, sizeof(*digits), GFP_KERNEL);
+	if (!digits)
+		return -ENOMEM;
+
+	ret = device_property_read_u8_array(dev, "titanmec,digits", digits,
+					    display->num_digits);
+	if (ret < 0) {
+		dev_err(dev, "Failed to read 'titanmec,digits' property: %d\n", ret);
+		return ret;
+	}
+
+	display->digits = devm_kcalloc(dev, display->num_digits, sizeof(*display->digits),
+				       GFP_KERNEL);
+	if (!display->digits)
+		return -ENOMEM;
+
+	for (i = 0; i < display->num_digits; i++) {
+		if (digits[i] >= display->controller->max_grids) {
+			dev_err(dev, "Digit grid %d exceeds controller max_grids %d\n",
+				digits[i], display->controller->max_grids);
+			return -EINVAL;
+		}
+
+		display->digits[i].grid = digits[i];
+		max_grid = umax(max_grid, digits[i]);
+	}
+
+	devm_kfree(dev, digits);
+
+	ret = device_property_read_u8_array(dev, "titanmec,segment-mapping",
+					    display->segment_mapping, DIGIT_SEGMENTS);
+	if (ret < 0) {
+		dev_err(dev, "Failed to read 'titanmec,segment-mapping' property: %d\n",
+			ret);
+		return ret;
+	}
+
+	display->digit_bitmask = 0;
+	for (i = 0; i < DIGIT_SEGMENTS; i++) {
+		if (display->segment_mapping[i] < MIN_SEGMENT ||
+		    display->segment_mapping[i] > MAX_SEGMENT) {
+			dev_err(dev,
+				"Invalid 'titanmec,segment-mapping' value: %d (must be between %d and %d)\n",
+				display->segment_mapping[i], MIN_SEGMENT, MAX_SEGMENT);
+			return -EINVAL;
+		}
+
+		display->digit_bitmask |= BIT(display->segment_mapping[i]);
+	}
+
+	display->num_leds = 0;
+	device_for_each_child_node(dev, child) {
+		u32 reg[2];
+
+		ret = fwnode_property_read_u32_array(child, "reg", reg, 2);
+		if (ret < 0) {
+			dev_err(dev, "Failed to read 'reg' property of led node: %d\n",
+				ret);
+			fwnode_handle_put(child);
+			return ret;
+		}
+
+		if (reg[0] >= display->controller->max_grids) {
+			dev_err(dev, "LED grid %d exceeds controller max_grids %d\n",
+				reg[0], display->controller->max_grids);
+			fwnode_handle_put(child);
+			return -EINVAL;
+		}
+
+		if (reg[1] < MIN_SEGMENT || reg[1] > MAX_SEGMENT) {
+			dev_err(dev,
+				"LED segment %d is invalid (must be between %d and %d)\n",
+				reg[1], MIN_SEGMENT, MAX_SEGMENT);
+			fwnode_handle_put(child);
+			return -EINVAL;
+		}
+
+		max_grid = umax(max_grid, reg[0]);
+		display->num_leds++;
+	}
+
+	dev_dbg(dev, "Number of LEDs: %d\n", display->num_leds);
+
+	display->display_data_len = max_grid + 1;
+	dev_dbg(dev, "Number of display grids: %zu\n", display->display_data_len);
+
+	display->display_data = devm_kcalloc(dev, display->display_data_len,
+					     sizeof(*display->display_data), GFP_KERNEL);
+	if (!display->display_data)
+		return -ENOMEM;
+
+	return 0;
+}
+
+/**
+ * tm16xx_probe - Probe function for tm16xx devices
+ * @display: Pointer to tm16xx_display structure
+ *
+ * Return: 0 on success, negative error code on failure
+ */
+static int tm16xx_probe(struct tm16xx_display *display)
+{
+	struct device *dev = display->dev;
+	struct fwnode_handle *child;
+	int ret, i;
+
+	ret = tm16xx_parse_dt(dev, display);
+	if (ret < 0) {
+		dev_err(dev, "Failed to parse device tree: %d\n", ret);
+		return ret;
+	}
+
+	mutex_init(&display->lock);
+	INIT_WORK(&display->flush_init, tm16xx_display_flush_init);
+
+	/* Initialize work structure with appropriate flush function */
+	if (display->transpose_display_data) {
+		INIT_WORK(&display->flush_display, tm16xx_display_flush_data_transposed);
+		dev_info(display->dev, "Operating in transposed mode\n");
+	} else {
+		INIT_WORK(&display->flush_display, tm16xx_display_flush_data);
+	}
+
+	display->main_led.name = TM16XX_DEVICE_NAME;
+	display->main_led.brightness = display->controller->max_brightness;
+	display->main_led.max_brightness = display->controller->max_brightness;
+	display->main_led.brightness_set = tm16xx_brightness_set;
+	display->main_led.groups = tm16xx_main_led_groups;
+	display->main_led.flags = LED_RETAIN_AT_SHUTDOWN | LED_CORE_SUSPENDRESUME;
+
+	ret = devm_led_classdev_register(dev, &display->main_led);
+	if (ret < 0) {
+		dev_err(dev, "Failed to register main LED: %d\n", ret);
+		return ret;
+	}
+
+	display->leds =
+		devm_kcalloc(dev, display->num_leds, sizeof(*display->leds), GFP_KERNEL);
+	if (!display->leds)
+		return -ENOMEM;
+
+	i = 0;
+	device_for_each_child_node(dev, child) {
+		struct tm16xx_led *led = &display->leds[i];
+		struct led_init_data led_init = {
+			.fwnode = child,
+			.devicename = display->main_led.name,
+			.devname_mandatory = true,
+		};
+		u32 reg[2];
+
+		ret = fwnode_property_read_u32_array(child, "reg", reg, 2);
+		if (ret < 0) {
+			fwnode_handle_put(child);
+			dev_err(dev, "Failed to read LED reg property: %d\n", ret);
+			return ret;
+		}
+
+		led->grid = reg[0];
+		led->segment = reg[1];
+
+		led->cdev.max_brightness = 1;
+		led->cdev.brightness_set = tm16xx_led_set;
+		led->cdev.flags = LED_RETAIN_AT_SHUTDOWN | LED_CORE_SUSPENDRESUME;
+
+		ret = devm_led_classdev_register_ext(dev, &led->cdev, &led_init);
+		if (ret < 0) {
+			fwnode_handle_put(child);
+			dev_err(dev, "Failed to register LED %s: %d\n", led->cdev.name,
+				ret);
+			return ret;
+		}
+
+		i++;
+	}
+
+	ret = tm16xx_display_init(display);
+	if (ret < 0) {
+		dev_err(display->dev, "Failed to initialize display: %d\n", ret);
+		return ret;
+	}
+
+	dev_info(display->dev, "Display initialized successfully\n");
+	return 0;
+}
+
+/* SPI specific code */
+static int tm16xx_spi_probe(struct spi_device *spi)
+{
+	const struct tm16xx_controller *controller;
+	struct tm16xx_display *display;
+	int ret;
+
+	controller = of_device_get_match_data(&spi->dev);
+	if (!controller)
+		return -EINVAL;
+
+	display = devm_kzalloc(&spi->dev, sizeof(*display), GFP_KERNEL);
+	if (!display)
+		return -ENOMEM;
+
+	display->client.spi = spi;
+	display->dev = &spi->dev;
+	display->controller = controller;
+
+	spi_set_drvdata(spi, display);
+
+	ret = tm16xx_probe(display);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static void tm16xx_spi_remove(struct spi_device *spi)
+{
+	struct tm16xx_display *display = spi_get_drvdata(spi);
+
+	tm16xx_display_remove(display);
+}
+
+// clang-format off
+static const struct of_device_id tm16xx_spi_of_match[] = {
+	{ .compatible = "titanmec,tm1618", .data = &tm1618_controller },
+	{ .compatible = "titanmec,tm1620", .data = &tm1628_controller },
+	{ .compatible = "titanmec,tm1628", .data = &tm1628_controller },
+	{ .compatible = "fdhisi,fd620", .data = &tm1628_controller },
+	{ .compatible = "fdhisi,fd628", .data = &tm1628_controller },
+	{ .compatible = "icore,aip1618", .data = &tm1618_controller },
+	{ .compatible = "icore,aip1628", .data = &tm1628_controller },
+	{ .compatible = "princeton,pt6964", .data = &tm1628_controller },
+	{ .compatible = "winrise,hbs658", .data = &hbs658_controller },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, tm16xx_spi_of_match);
+
+static const struct spi_device_id tm16xx_spi_id[] = {
+	{ "tm1618", 0 },
+	{ "tm1620", 0 },
+	{ "tm1628", 0 },
+	{ "fd620", 0 },
+	{ "fd628", 0 },
+	{ "aip1618", 0 },
+	{ "aip1628", 0 },
+	{ "pt6964", 0 },
+	{ "hbs658", 0 },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(spi, tm16xx_spi_id);
+// clang-format on
+
+static struct spi_driver tm16xx_spi_driver = {
+	.driver = {
+		.name = TM16XX_DRIVER_NAME,
+		.of_match_table = tm16xx_spi_of_match,
+	},
+	.probe = tm16xx_spi_probe,
+	.remove = tm16xx_spi_remove,
+	.shutdown = tm16xx_spi_remove,
+	.id_table = tm16xx_spi_id,
+};
+
+/* I2C specific code */
+static int tm16xx_i2c_probe(struct i2c_client *client)
+{
+	const struct tm16xx_controller *controller;
+	struct tm16xx_display *display;
+	int ret;
+
+	controller = of_device_get_match_data(&client->dev);
+	if (!controller)
+		return -EINVAL;
+
+	display = devm_kzalloc(&client->dev, sizeof(*display), GFP_KERNEL);
+	if (!display)
+		return -ENOMEM;
+
+	display->client.i2c = client;
+	display->dev = &client->dev;
+	display->controller = controller;
+
+	i2c_set_clientdata(client, display);
+
+	ret = tm16xx_probe(display);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static void tm16xx_i2c_remove(struct i2c_client *client)
+{
+	struct tm16xx_display *display = i2c_get_clientdata(client);
+
+	tm16xx_display_remove(display);
+}
+
+// clang-format off
+static const struct of_device_id tm16xx_i2c_of_match[] = {
+	{ .compatible = "titanmec,tm1650", .data = &tm1650_controller },
+	{ .compatible = "icore,aip650", .data = &tm1650_controller },
+	{ .compatible = "fdhisi,fd650", .data = &tm1650_controller },
+	{ .compatible = "fdhisi,fd6551", .data = &fd6551_controller },
+	{ .compatible = "fdhisi,fd655", .data = &fd655_controller },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, tm16xx_i2c_of_match);
+
+static const struct i2c_device_id tm16xx_i2c_id[] = {
+	{ "tm1650", 0 },
+	{ "aip650", 0 },
+	{ "fd650", 0 },
+	{ "fd6551", 0 },
+	{ "fd655", 0 },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(i2c, tm16xx_i2c_id);
+// clang-format on
+
+static struct i2c_driver tm16xx_i2c_driver = {
+	.driver = {
+		.name = TM16XX_DRIVER_NAME,
+		.of_match_table = tm16xx_i2c_of_match,
+	},
+	.probe = tm16xx_i2c_probe,
+	.remove = tm16xx_i2c_remove,
+	.shutdown = tm16xx_i2c_remove,
+	.id_table = tm16xx_i2c_id,
+};
+
+static int __init tm16xx_init(void)
+{
+	int ret;
+
+	ret = spi_register_driver(&tm16xx_spi_driver);
+	if (ret)
+		return ret;
+
+	ret = i2c_add_driver(&tm16xx_i2c_driver);
+	if (ret) {
+		spi_unregister_driver(&tm16xx_spi_driver);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void __exit tm16xx_exit(void)
+{
+	i2c_del_driver(&tm16xx_i2c_driver);
+	spi_unregister_driver(&tm16xx_spi_driver);
+}
+
+module_init(tm16xx_init);
+module_exit(tm16xx_exit);
+
+MODULE_AUTHOR("Jean-François Lessard");
+MODULE_DESCRIPTION("TM16XX Compatible LED Display Controllers");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("spi:tm16xx");
+MODULE_ALIAS("i2c:tm16xx");
-- 
2.43.0