diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index 2d70c945b20a..9a9528e59c36 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -422,6 +422,18 @@ config TOUCHSCREEN_HYCON_HY46XX
 	  To compile this driver as a module, choose M here: the
 	  module will be called hycon-hy46xx.
 
+config TOUCHSCREEN_HYNITRON_CSTXXX
+	tristate "Hynitron touchscreen support"
+	depends on I2C
+	help
+	  Say Y here if you have a touchscreen using a Hynitron
+	  touchscreen controller.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called hynitron-cstxxx.
+
 config TOUCHSCREEN_ILI210X
 	tristate "Ilitek ILI210X based touchscreen"
 	depends on I2C
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index 557f84fd2075..43860ca19b98 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -47,6 +47,7 @@ obj-$(CONFIG_TOUCHSCREEN_EXC3000)	+= exc3000.o
 obj-$(CONFIG_TOUCHSCREEN_FUJITSU)	+= fujitsu_ts.o
 obj-$(CONFIG_TOUCHSCREEN_GOODIX)	+= goodix_ts.o
 obj-$(CONFIG_TOUCHSCREEN_HIDEEP)	+= hideep.o
+obj-$(CONFIG_TOUCHSCREEN_HYNITRON_CSTXXX)	+= hynitron_cstxxx.o
 obj-$(CONFIG_TOUCHSCREEN_ILI210X)	+= ili210x.o
 obj-$(CONFIG_TOUCHSCREEN_ILITEK)	+= ilitek_ts_i2c.o
 obj-$(CONFIG_TOUCHSCREEN_IMAGIS)	+= imagis.o
diff --git a/drivers/input/touchscreen/hynitron_cstxxx.c b/drivers/input/touchscreen/hynitron_cstxxx.c
new file mode 100644
index 000000000000..11701ff39eb1
--- /dev/null
+++ b/drivers/input/touchscreen/hynitron_cstxxx.c
@@ -0,0 +1,508 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Driver for Hynitron cstxxx Touchscreen
+ *
+ *  Copyright (c) 2022 Chris Morgan <macromorgan@hotmail.com>
+ *
+ *  This code is based on hynitron_core.c authored by Hynitron.
+ *  Note that no datasheet was available, so much of these registers
+ *  are undocumented. This is essentially a cleaned-up version of the
+ *  vendor driver with support removed for hardware I cannot test and
+ *  device-specific functions replated with generic functions wherever
+ *  possible.
+ */
+
+#include <asm/unaligned.h>
+#include <linux/delay.h>
+#include <linux/gpio.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/input/mt.h>
+#include <linux/input/touchscreen.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+/* Per chip data */
+struct hynitron_ts_chip_data {
+	unsigned int max_touch_num;
+	u32 ic_chkcode;
+	int (*firmware_info)(struct i2c_client *client);
+	int (*bootloader_enter)(struct i2c_client *client);
+	int (*init_input)(struct i2c_client *client);
+	void (*report_touch)(struct i2c_client *client);
+};
+
+/* Data generic to all (supported and non-supported) controllers. */
+struct hynitron_ts_data {
+	const struct hynitron_ts_chip_data *pdata;
+	struct i2c_client *client;
+	struct input_dev *input_dev;
+	struct touchscreen_properties prop;
+	struct gpio_desc *reset_gpio;
+	struct gpio_desc *irq_gpio;
+};
+
+/*
+ * Since I have no datasheet, these values are guessed and/or assumed
+ * based on observation and testing.
+ */
+#define CST3XX_FIRMWARE_INFO_START_CMD		0x01d1
+#define CST3XX_FIRMWARE_INFO_END_CMD		0x09d1
+#define CST3XX_FIRMWARE_CHK_CODE_REG		0xfcd1
+#define CST3XX_FIRMWARE_VERSION_REG		0x08d2
+#define CST3XX_FIRMWARE_VER_INVALID_VAL		0xa5a5a5a5
+
+#define CST3XX_BOOTLDR_PROG_CMD			0xaa01a0
+#define CST3XX_BOOTLDR_PROG_CHK_REG		0x02a0
+#define CST3XX_BOOTLDR_CHK_VAL			0xac
+
+#define CST3XX_TOUCH_DATA_PART_REG		0x00d0
+#define CST3XX_TOUCH_DATA_FULL_REG		0x07d0
+#define CST3XX_TOUCH_DATA_CHK_VAL		0xab
+#define CST3XX_TOUCH_DATA_TOUCH_VAL		0x03
+#define CST3XX_TOUCH_DATA_STOP_CMD		0xab00d0
+#define CST3XX_TOUCH_COUNT_MASK			GENMASK(6, 0)
+
+
+/*
+ * Hard coded reset delay value of 20ms not IC dependent in
+ * vendor driver.
+ */
+static void hyn_reset_proc(struct i2c_client *client, int delay)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+
+	gpiod_set_value_cansleep(ts_data->reset_gpio, 1);
+	mdelay(20);
+	gpiod_set_value_cansleep(ts_data->reset_gpio, 0);
+	if (delay)
+		mdelay(delay);
+}
+
+static irqreturn_t hyn_interrupt_handler(int irq, void *dev_id)
+{
+	struct i2c_client *client = dev_id;
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+
+	ts_data->pdata->report_touch(client);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * The vendor driver would retry twice before failing to read or write
+ * to the i2c device.
+ */
+
+static int cst3xx_i2c_write(struct i2c_client *client,
+			    unsigned char *buf, int len)
+{
+	int ret;
+	int retries = 0;
+
+	while (retries < 2) {
+		ret = i2c_master_send(client, buf, len);
+		if (ret == len)
+			return 0;
+		if (ret <= 0)
+			retries++;
+		else
+			break;
+	}
+
+	return ret < 0 ? ret : -EIO;
+}
+
+static int cst3xx_i2c_read_register(struct i2c_client *client, u16 reg,
+				    u8 *val, u16 len)
+{
+	__le16 buf = cpu_to_le16(reg);
+	struct i2c_msg msgs[] = {
+		{
+			.addr = client->addr,
+			.flags = 0,
+			.len = 2,
+			.buf = (u8 *)&buf,
+		},
+		{
+			.addr = client->addr,
+			.flags = I2C_M_RD,
+			.len = len,
+			.buf = val,
+		}
+	};
+	int ret;
+
+	ret = i2c_transfer(client->adapter, msgs, 2);
+	if (ret >= 0)
+		ret = (ret == ARRAY_SIZE(msgs) ? 0 : -EIO);
+
+	if (ret)
+		dev_err(&client->dev,
+			"Error reading %d bytes from 0x%04x: %d\n",
+			len, reg, ret);
+
+	return ret;
+}
+
+static int cst3xx_firmware_info(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+	int ret;
+	u32 tmp;
+	unsigned char buf[4];
+
+	/*
+	 * Tests suggest this command needed to read firmware regs.
+	 */
+	put_unaligned_le16(CST3XX_FIRMWARE_INFO_START_CMD, buf);
+	ret = cst3xx_i2c_write(client, buf, 2);
+	if (ret < 0)
+		return -EIO;
+
+	mdelay(10);
+
+	/*
+	 * Read register for check-code to determine if device detected
+	 * correctly.
+	 */
+	ret = cst3xx_i2c_read_register(client, CST3XX_FIRMWARE_CHK_CODE_REG,
+				       buf, 4);
+	if (ret < 0)
+		return -EIO;
+
+	tmp = get_unaligned_le32(buf);
+	if ((tmp & 0xffff0000) != ts_data->pdata->ic_chkcode) {
+		dev_err(&client->dev, "%s ic mismatch\n", __func__);
+		return -ENODEV;
+	}
+
+	mdelay(10);
+
+	/* Read firmware version and test if firmware missing. */
+	ret = cst3xx_i2c_read_register(client, CST3XX_FIRMWARE_VERSION_REG,
+				       buf, 4);
+	if (ret < 0)
+		return -EIO;
+
+	tmp = get_unaligned_le32(buf);
+	if (tmp == CST3XX_FIRMWARE_VER_INVALID_VAL) {
+		dev_err(&client->dev, "Device firmware missing\n");
+		return -ENODEV;
+	}
+
+	/*
+	 * Tests suggest cmd required to exit reading firmware regs.
+	 */
+	put_unaligned_le16(CST3XX_FIRMWARE_INFO_END_CMD, buf);
+	ret = cst3xx_i2c_write(client, buf, 2);
+	if (ret < 0)
+		return -EIO;
+
+	mdelay(5);
+
+	return 0;
+}
+
+static int cst3xx_bootloader_enter(struct i2c_client *client)
+{
+	int ret;
+	u8 retry;
+	u32 tmp;
+	unsigned char buf[3];
+
+	for (retry = 0; retry < 5; retry++) {
+		hyn_reset_proc(client, (7 + retry));
+		/* set cmd to enter program mode */
+		put_unaligned_le24(CST3XX_BOOTLDR_PROG_CMD, buf);
+		ret = cst3xx_i2c_write(client, buf, 3);
+		if (ret < 0)
+			continue;
+		mdelay(2);
+
+		/* check whether in program mode */
+		ret = cst3xx_i2c_read_register(client,
+					       CST3XX_BOOTLDR_PROG_CHK_REG,
+					       buf, 1);
+		tmp = get_unaligned(buf);
+
+		if (ret < 0)
+			continue;
+
+		if (tmp == CST3XX_BOOTLDR_CHK_VAL)
+			break;
+	}
+
+	if (tmp != CST3XX_BOOTLDR_CHK_VAL) {
+		dev_err(&client->dev, "%s unable to enter bootloader mode\n",
+			__func__);
+		return -ENODEV;
+	}
+
+	hyn_reset_proc(client, 40);
+
+	return 0;
+}
+
+static void cst3xx_touch_update(struct hynitron_ts_data *ts_data,
+				s32 id, s32 x, s32 y, s32 w)
+{
+	input_mt_slot(ts_data->input_dev, id);
+	input_mt_report_slot_state(ts_data->input_dev, MT_TOOL_FINGER, 1);
+	touchscreen_report_pos(ts_data->input_dev, &ts_data->prop, x, y, true);
+	input_report_abs(ts_data->input_dev, ABS_MT_TOUCH_MAJOR, w);
+}
+
+static int cst3xx_finish_touch_read(struct i2c_client *client)
+{
+	unsigned char buf[3];
+	int err;
+
+	put_unaligned_le24(CST3XX_TOUCH_DATA_STOP_CMD, buf);
+	err = cst3xx_i2c_write(client, buf, 3);
+	if (err < 0) {
+		dev_err(&client->dev, "send read touch info ending failed.\n");
+		return err;
+	}
+
+	return 0;
+}
+
+/*
+ * Handle events from IRQ. Note that for cst3xx it appears that IRQ
+ * fires continuously while touched, otherwise once every 1500ms
+ * when not touched (assume touchscreen waking up periodically).
+ * Note buffer is sized for 5 fingers, if more needed buffer must
+ * be increased. The buffer contains 5 bytes for each touch point,
+ * a touch count byte, a check byte, and then a second check byte after
+ * all other touch points.
+ *
+ * For example 1 touch would look like this:
+ * touch1[5]:touch_count[1]:chk_byte[1]
+ *
+ * 3 touches would look like this:
+ * touch1[5]:touch_count[1]:chk_byte[1]:touch2[5]:touch3[5]:chk_byte[1]
+ */
+static void cst3xx_touch_report(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+	unsigned char buf[28];
+	unsigned char finger_id, sw;
+	unsigned int input_x = 0;
+	unsigned int input_y = 0;
+	unsigned int input_w = 0;
+	int idx = 0;
+	int i, err;
+	int touch_cnt, end_byte;
+
+	/* Read and validate the first bits of input data. */
+	err = cst3xx_i2c_read_register(client, CST3XX_TOUCH_DATA_PART_REG,
+				       buf, 28);
+	if ((err < 0) || (buf[6] != CST3XX_TOUCH_DATA_CHK_VAL) ||
+	    (buf[0] == CST3XX_TOUCH_DATA_CHK_VAL)) {
+		dev_err(&client->dev, "cst3xx touch read failure\n");
+		return;
+	}
+
+	/* Report to the device we're done reading the touch data. */
+	err = cst3xx_finish_touch_read(client);
+	if (err < 0) {
+		dev_err(&client->dev, "cst3xx touch read failure\n");
+		return;
+	}
+
+	touch_cnt = buf[5] & CST3XX_TOUCH_COUNT_MASK;
+
+	/* If no touches registered, clear the input slots. */
+	if (touch_cnt == 0) {
+		input_mt_sync_frame(ts_data->input_dev);
+		input_sync(ts_data->input_dev);
+		return;
+	}
+
+	/*
+	 * Check the check bit of the last touch slot. The check bit is
+	 * always present after touch point 1 for valid data, and then
+	 * appears as the last byte after all other touch data.
+	 */
+	if (touch_cnt > 1) {
+		end_byte = touch_cnt * 5 + 2;
+		if (buf[end_byte] != CST3XX_TOUCH_DATA_CHK_VAL) {
+			dev_err(&client->dev, "cst3xx touch read failure\n");
+			return;
+		}
+	}
+
+	/* Parse through the buffer to capture touch data. */
+	for (i = 0; i < touch_cnt; i++) {
+		input_x = ((buf[idx + 1] << 4) | ((buf[idx + 3] >> 4) & 0x0f));
+		input_y = ((buf[idx + 2] << 4) | (buf[idx + 3] & 0x0f));
+		input_w = (buf[idx + 4] >> 3);
+		sw = (buf[idx] & 0x0f) >> 1;
+		finger_id = (buf[idx] >> 4) & 0x0f;
+
+		/* Sanity check we don't have more fingers than we expect */
+		if (ts_data->pdata->max_touch_num < finger_id) {
+			dev_err(&client->dev, "cst3xx touch read failure\n");
+			break;
+		}
+
+		/* sw value of 0 means no touch, 0x03 means touch */
+		if (sw == CST3XX_TOUCH_DATA_TOUCH_VAL)
+			cst3xx_touch_update(ts_data, finger_id,
+					    input_x, input_y, input_w);
+
+		idx += 5;
+
+		/* Skip the 2 bits between point 1 and point 2 */
+		if (i == 0)
+			idx += 2;
+	}
+
+	input_mt_sync_frame(ts_data->input_dev);
+	input_sync(ts_data->input_dev);
+}
+
+static int cst3xx_input_dev_int(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+	int err;
+
+	ts_data->input_dev = devm_input_allocate_device(&ts_data->client->dev);
+	if (!ts_data->input_dev) {
+		dev_err(&ts_data->client->dev,
+			"Failed to allocate input device.\n");
+		return -ENOMEM;
+	}
+
+	ts_data->input_dev->name = "Hynitron cst3xx Touchscreen";
+	ts_data->input_dev->phys = "input/ts";
+	ts_data->input_dev->id.bustype = BUS_I2C;
+
+	input_set_drvdata(ts_data->input_dev, ts_data);
+
+	input_set_capability(ts_data->input_dev, EV_ABS, ABS_MT_POSITION_X);
+	input_set_capability(ts_data->input_dev, EV_ABS, ABS_MT_POSITION_Y);
+	input_set_abs_params(ts_data->input_dev, ABS_MT_TOUCH_MAJOR,
+			     0, 255, 0, 0);
+
+	touchscreen_parse_properties(ts_data->input_dev, true, &ts_data->prop);
+
+	if (!ts_data->prop.max_x || !ts_data->prop.max_y) {
+		dev_err(&client->dev,
+			"Invalid x/y (%d, %d), using defaults\n",
+			ts_data->prop.max_x, ts_data->prop.max_y);
+		ts_data->prop.max_x = 1152;
+		ts_data->prop.max_y = 1920;
+		input_abs_set_max(ts_data->input_dev,
+				  ABS_MT_POSITION_X, ts_data->prop.max_x);
+		input_abs_set_max(ts_data->input_dev,
+				  ABS_MT_POSITION_Y, ts_data->prop.max_y);
+	}
+
+	err = input_mt_init_slots(ts_data->input_dev,
+				  ts_data->pdata->max_touch_num,
+				  INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
+	if (err < 0) {
+		dev_err(&ts_data->client->dev,
+			"Input device registration failed\n");
+		return err;
+	}
+
+	err = input_register_device(ts_data->input_dev);
+	if (err < 0) {
+		dev_err(&ts_data->client->dev,
+			"Input device registration failed\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static int hyn_probe(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data;
+	int err;
+
+	ts_data = devm_kzalloc(&client->dev, sizeof(*ts_data), GFP_KERNEL);
+	if (!ts_data)
+		return -ENOMEM;
+
+	ts_data->client = client;
+	i2c_set_clientdata(client, ts_data);
+
+	ts_data->reset_gpio = devm_gpiod_get(&client->dev,
+					     "reset", GPIOD_OUT_LOW);
+	err = PTR_ERR_OR_ZERO(ts_data->reset_gpio);
+	if (err < 0) {
+		dev_err(&client->dev, "request reset gpio failed: %d\n", err);
+		return err;
+	}
+
+	ts_data->pdata = of_device_get_match_data(&client->dev);
+	if (!ts_data->pdata)
+		return -EINVAL;
+
+	hyn_reset_proc(client, 60);
+
+	err = ts_data->pdata->bootloader_enter(client);
+	if (err < 0)
+		return err;
+
+	err = ts_data->pdata->init_input(client);
+	if (err < 0)
+		return err;
+
+	err = ts_data->pdata->firmware_info(client);
+	if (err < 0)
+		return err;
+
+	err = devm_request_threaded_irq(&client->dev, client->irq, NULL,
+					hyn_interrupt_handler,
+					IRQF_ONESHOT,
+					"Hynitron Touch Int", client);
+	if (err < 0) {
+		dev_err(&client->dev, "failed to request IRQ\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static const struct hynitron_ts_chip_data cst3xx_data = {
+	.max_touch_num		= 5,
+	.ic_chkcode		= 0xcaca0000,
+	.firmware_info		= &cst3xx_firmware_info,
+	.bootloader_enter	= &cst3xx_bootloader_enter,
+	.init_input		= &cst3xx_input_dev_int,
+	.report_touch		= &cst3xx_touch_report,
+};
+
+static const struct i2c_device_id hyn_tpd_id[] = {
+	{ .name = "hynitron_ts", 0 },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(i2c, hyn_tpd_id);
+
+static const struct of_device_id hyn_dt_match[] = {
+	{ .compatible = "hynitron,cst340", .data = &cst3xx_data },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, hyn_dt_match);
+
+static struct i2c_driver hynitron_i2c_driver = {
+	.driver = {
+		.name = "Hynitron-TS",
+		.of_match_table = of_match_ptr(hyn_dt_match),
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+	.id_table = hyn_tpd_id,
+	.probe_new = hyn_probe,
+};
+
+module_i2c_driver(hynitron_i2c_driver);
+
+MODULE_AUTHOR("Chris Morgan");
+MODULE_DESCRIPTION("Hynitron Touchscreen Driver");
+MODULE_LICENSE("GPL");
