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From: Kamel Bouhara <kamel.bouhara@bootlin.com>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	Rob Herring <robh+dt@kernel.org>,
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Henrik Rydberg <rydberg@bitmath.org>,
	linux-input@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	devicetree@vger.kernel.org,
	Marco Felsch <m.felsch@pengutronix.de>,
	Jeff LaBundy <jeff@labundy.com>
Cc: catalin.popescu@leica-geosystems.com,
	mark.satterthwaite@touchnetix.com,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	Gregory Clement <gregory.clement@bootlin.com>,
	bsp-development.geo@leica-geosystems.com,
	Kamel Bouhara <kamel.bouhara@bootlin.com>
Subject: [PATCH v13 3/3] Input: Add TouchNetix axiom i2c touchscreen driver
Date: Mon,  3 Jun 2024 17:39:25 +0200
Message-ID: <20240603153929.29218-4-kamel.bouhara@bootlin.com>
In-Reply-To: <20240603153929.29218-1-kamel.bouhara@bootlin.com>
References: <20240603153929.29218-1-kamel.bouhara@bootlin.com>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

Add a new driver for the TouchNetix's axiom family of
touchscreen controllers. This driver only supports i2c
and can be later adapted for SPI and USB support.

Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
---
 MAINTAINERS                                  |   2 +
 drivers/input/touchscreen/Kconfig            |  14 +
 drivers/input/touchscreen/Makefile           |   1 +
 drivers/input/touchscreen/touchnetix_axiom.c | 657 +++++++++++++++++++
 4 files changed, 674 insertions(+)
 create mode 100644 drivers/input/touchscreen/touchnetix_axiom.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 225309db4110..a3ece12e32d7 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -22744,9 +22744,11 @@ F:	drivers/platform/x86/toshiba-wmi.c
 
 TOUCHNETIX AXIOM I2C TOUCHSCREEN DRIVER
 M:	Kamel Bouhara <kamel.bouhara@bootlin.com>
+M:	bsp-development.geo@leica-geosystems.com
 L:	linux-input@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/input/touchscreen/touchnetix,ax54a.yaml
+F:	drivers/input/touchscreen/touchnetix_axiom.c
 
 TPM DEVICE DRIVER
 M:	Peter Huewe <peterhuewe@gmx.de>
diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index c821fe3ee794..1ce8f1c25625 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -834,6 +834,20 @@ config TOUCHSCREEN_MIGOR
 	  To compile this driver as a module, choose M here: the
 	  module will be called migor_ts.
 
+config TOUCHSCREEN_TOUCHNETIX_AXIOM
+	tristate "TouchNetix AXIOM based touchscreen controllers"
+	depends on I2C
+	select CRC16
+	select REGMAP_I2C
+	help
+	  Say Y here if you have a axiom touchscreen connected to
+	  your system.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called axiom.
+
 config TOUCHSCREEN_TOUCHRIGHT
 	tristate "Touchright serial touchscreen"
 	select SERIO
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index a81cb5aa21a5..6ce7b804adc7 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -91,6 +91,7 @@ obj-$(CONFIG_TOUCHSCREEN_SUR40)		+= sur40.o
 obj-$(CONFIG_TOUCHSCREEN_SURFACE3_SPI)	+= surface3_spi.o
 obj-$(CONFIG_TOUCHSCREEN_TI_AM335X_TSC)	+= ti_am335x_tsc.o
 obj-$(CONFIG_TOUCHSCREEN_TOUCHIT213)	+= touchit213.o
+obj-$(CONFIG_TOUCHSCREEN_TOUCHNETIX_AXIOM)	+= touchnetix_axiom.o
 obj-$(CONFIG_TOUCHSCREEN_TOUCHRIGHT)	+= touchright.o
 obj-$(CONFIG_TOUCHSCREEN_TOUCHWIN)	+= touchwin.o
 obj-$(CONFIG_TOUCHSCREEN_TS4800)	+= ts4800-ts.o
diff --git a/drivers/input/touchscreen/touchnetix_axiom.c b/drivers/input/touchscreen/touchnetix_axiom.c
new file mode 100644
index 000000000000..09550847392e
--- /dev/null
+++ b/drivers/input/touchscreen/touchnetix_axiom.c
@@ -0,0 +1,657 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * TouchNetix axiom Touchscreen Driver
+ *
+ * Copyright (C) 2020-2023 TouchNetix Ltd.
+ *
+ * Author(s): Bart Prescott <bartp@baasheep.co.uk>
+ *            Pedro Torruella <pedro.torruella@touchnetix.com>
+ *            Mark Satterthwaite <mark.satterthwaite@touchnetix.com>
+ *            Hannah Rossiter <hannah.rossiter@touchnetix.com>
+ *            Kamel Bouhara <kamel.bouhara@bootlin.com>
+ *
+ */
+#include <linux/bitfield.h>
+#include <linux/crc16.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/input/mt.h>
+#include <linux/input/touchscreen.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/regmap.h>
+
+#include <asm/unaligned.h>
+#define AXIOM_PROX_LEVEL		-128
+#define AXIOM_DMA_OPS_DELAY_USEC	250
+#define AXIOM_STARTUP_TIME_MS		110
+/*
+ * Register group u31 has 2 pages for usage table entries.
+ */
+#define AXIOM_U31_MAX_USAGES		0xff
+#define AXIOM_U31_BYTES_PER_USAGE	6
+#define AXIOM_U31_PAGE0_LENGTH		0x0C
+#define AXIOM_U31_BOOTMODE_MASK		BIT(7)
+#define AXIOM_U31_DEVID_MASK		GENMASK(14, 0)
+
+#define AXIOM_MAX_REPORT_LEN		0x7f
+
+#define AXIOM_CMD_HEADER_READ_MASK	BIT(15)
+#define AXIOM_U41_MAX_TARGETS		10
+
+#define AXIOM_U46_AUX_CHANNELS		4
+#define AXIOM_U46_AUX_MASK		GENMASK(11, 0)
+
+#define AXIOM_COMMS_MAX_USAGE_PAGES	3
+#define AXIOM_COMMS_PAGE_SIZE		256
+#define AXIOM_COMMS_REPORT_LEN_MASK	GENMASK(6, 0)
+
+#define AXIOM_REPORT_USAGE_ID		0x34
+#define AXIOM_DEVINFO_USAGE_ID		0x31
+#define AXIOM_USAGE_2HB_REPORT_ID	0x01
+#define AXIOM_USAGE_2AUX_REPORT_ID	0x46
+#define AXIOM_USAGE_2DCTS_REPORT_ID	0x41
+
+#define AXIOM_PAGE_OFFSET_MASK		GENMASK(6, 0)
+
+struct axiom_devinfo {
+	__le16 device_id;
+	u8 fw_minor;
+	u8 fw_major;
+	u8 fw_info_extra;
+	u8 tcp_revision;
+	u8 bootloader_fw_minor;
+	u8 bootloader_fw_major;
+	__le16 jedec_id;
+	u8 num_usages;
+} __packed;
+
+/*
+ * Describes parameters of a specific usage, essentially a single element of
+ * the "Usage Table"
+ */
+struct axiom_usage_entry {
+	u8 id;
+	u8 is_report;
+	u8 start_page;
+	u8 num_pages;
+};
+
+/*
+ * Represents state of a touch or target when detected prior to a touch (eg.
+ * hover or proximity events).
+ */
+enum axiom_target_state {
+	AXIOM_TARGET_STATE_NOT_PRESENT = 0,
+	AXIOM_TARGET_STATE_PROX = 1,
+	AXIOM_TARGET_STATE_HOVER = 2,
+	AXIOM_TARGET_STATE_TOUCHING = 3,
+};
+
+struct axiom_u41_target {
+	enum axiom_target_state state;
+	u16 x;
+	u16 y;
+	s8 z;
+	bool insert;
+	bool touch;
+};
+
+struct axiom_target_report {
+	u8 index;
+	u8 present;
+	u16 x;
+	u16 y;
+	s8 z;
+};
+
+struct axiom_cmd_header {
+	__le16 target_address;
+	__le16 length;
+} __packed;
+
+struct axiom_data {
+	struct axiom_devinfo devinfo;
+	struct device *dev;
+	struct gpio_desc *reset_gpio;
+	struct i2c_client *client;
+	struct input_dev *input_dev;
+	u32 max_report_len;
+	u8 rx_buf[AXIOM_COMMS_MAX_USAGE_PAGES * AXIOM_COMMS_PAGE_SIZE];
+	struct axiom_u41_target targets[AXIOM_U41_MAX_TARGETS];
+	struct axiom_usage_entry usage_table[AXIOM_U31_MAX_USAGES];
+	bool usage_table_populated;
+	struct regmap *regmap;
+	struct touchscreen_properties	prop;
+};
+
+static const struct regmap_config axiom_i2c_regmap_config = {
+	.reg_bits = 32,
+	.reg_format_endian = REGMAP_ENDIAN_LITTLE,
+	.val_bits = 8,
+	.val_format_endian = REGMAP_ENDIAN_LITTLE,
+};
+
+/*
+ * axiom devices are typically configured to report touches at a rate
+ * of 100Hz (10ms) for systems that require polling for reports.
+ * When reports are polled, it will be expected to occasionally
+ * observe the overflow bit being set in the reports.
+ * This indicates that reports are not being read fast enough.
+ */
+#define POLL_INTERVAL_DEFAULT_MS 10
+
+/* Translate usage/page/offset triplet into physical address. */
+static u16 axiom_usage_to_target_address(struct axiom_data *ts, u8 usage, u8 page,
+					 char offset)
+{
+	/* At the moment the convention is that u31 is always at physical address 0x0 */
+	if (!ts->usage_table_populated) {
+		if (usage == AXIOM_DEVINFO_USAGE_ID)
+			return ((page << 8) + offset);
+		else
+			return 0xffff;
+	}
+
+	if (page >= ts->usage_table[usage].num_pages) {
+		dev_err(ts->dev, "Invalid usage table! usage: u%02x, page: %02x, offset: %02x\n",
+			usage, page, offset);
+		return 0xffff;
+	}
+
+	return ((ts->usage_table[usage].start_page + page) << 8) + offset;
+}
+
+static int axiom_read(struct axiom_data *ts, u8 usage, u8 page, void *buf, u16 len)
+{
+	struct axiom_cmd_header cmd_header;
+	u32 preamble;
+	int ret;
+
+	cmd_header.target_address = cpu_to_le16(axiom_usage_to_target_address(ts, usage, page, 0));
+	cmd_header.length = cpu_to_le16(len | AXIOM_CMD_HEADER_READ_MASK);
+
+	preamble = get_unaligned_le32(&cmd_header);
+
+	ret = regmap_write(ts->regmap, preamble, 0);
+	if (ret) {
+		dev_err(ts->dev, "failed to write preamble, error %d\n", ret);
+		return ret;
+	}
+
+	ret = regmap_raw_read(ts->regmap, 0, buf, len);
+	if (ret) {
+		dev_err(ts->dev, "failed to read target address %04x, error %d\n",
+			cmd_header.target_address, ret);
+		return ret;
+	}
+
+	/* Wait device's DMA operations */
+	usleep_range(AXIOM_DMA_OPS_DELAY_USEC, AXIOM_DMA_OPS_DELAY_USEC + 50);
+
+	return 0;
+}
+
+/*
+ * One of the main purposes for reading the usage table is to identify
+ * which usages reside at which target address.
+ * When performing subsequent reads or writes to AXIOM, the target address
+ * is used to specify which usage is being accessed.
+ * Consider the following discovery code which will build up the usage table.
+ */
+static u32 axiom_populate_usage_table(struct axiom_data *ts)
+{
+	struct axiom_usage_entry *usage_table;
+	u8 *rx_data = ts->rx_buf;
+	u32 max_report_len = 0;
+	u32 usage_id;
+	int error;
+
+	usage_table = ts->usage_table;
+
+	/* Read the second page of usage u31 to get the usage table */
+	error = axiom_read(ts, AXIOM_DEVINFO_USAGE_ID, 1, rx_data,
+			   (AXIOM_U31_BYTES_PER_USAGE * ts->devinfo.num_usages));
+
+	if (error)
+		return error;
+
+	for (usage_id = 0; usage_id < ts->devinfo.num_usages; usage_id++) {
+		u16 offset = (usage_id * AXIOM_U31_BYTES_PER_USAGE);
+		u8 id = rx_data[offset + 0];
+		u8 start_page = rx_data[offset + 1];
+		u8 num_pages = rx_data[offset + 2];
+		u32 max_offset = ((rx_data[offset + 3] & AXIOM_PAGE_OFFSET_MASK) + 1) * 2;
+
+		usage_table[id].is_report = !num_pages;
+
+		/* Store the entry into the usage table */
+		usage_table[id].id = id;
+		usage_table[id].start_page = start_page;
+		usage_table[id].num_pages = num_pages;
+
+		dev_dbg(ts->dev, "Usage u%02x Info: %*ph\n", id, AXIOM_U31_BYTES_PER_USAGE,
+			&rx_data[offset]);
+
+		/* Identify the max report length the module will receive */
+		if (usage_table[id].is_report && max_offset > max_report_len)
+			max_report_len = max_offset;
+	}
+
+	ts->usage_table_populated = true;
+
+	return max_report_len;
+}
+
+static int axiom_discover(struct axiom_data *ts)
+{
+	int error;
+
+	/*
+	 * Fetch the first page of usage u31 to get the
+	 * device information and the number of usages
+	 */
+	error = axiom_read(ts, AXIOM_DEVINFO_USAGE_ID, 0, &ts->devinfo, AXIOM_U31_PAGE0_LENGTH);
+	if (error)
+		return error;
+
+	dev_dbg(ts->dev, "  Boot Mode      : %s\n",
+		FIELD_GET(AXIOM_U31_BOOTMODE_MASK,
+			  le16_to_cpu(ts->devinfo.device_id)) ? "BLP" : "TCP");
+	dev_dbg(ts->dev, "  Device ID      : %04lx\n",
+		FIELD_GET(AXIOM_U31_DEVID_MASK, le16_to_cpu(ts->devinfo.device_id)));
+	dev_dbg(ts->dev, "  Firmware Rev   : %02x.%02x\n", ts->devinfo.fw_major,
+		ts->devinfo.fw_minor);
+	dev_dbg(ts->dev, "  Bootloader Rev : %02x.%02x\n", ts->devinfo.bootloader_fw_major,
+		ts->devinfo.bootloader_fw_minor);
+	dev_dbg(ts->dev, "  FW Extra Info  : %04x\n", ts->devinfo.fw_info_extra);
+	dev_dbg(ts->dev, "  Silicon        : %04x\n", le16_to_cpu(ts->devinfo.jedec_id));
+	dev_dbg(ts->dev, "  Number usages        : %04x\n", ts->devinfo.num_usages);
+
+	ts->max_report_len = axiom_populate_usage_table(ts);
+	if (!ts->max_report_len || !ts->devinfo.num_usages ||
+	    ts->max_report_len > AXIOM_MAX_REPORT_LEN) {
+		dev_err(ts->dev, "Invalid report length or usages number");
+		return -EINVAL;
+	}
+
+	dev_dbg(ts->dev, "Max Report Length: %u\n", ts->max_report_len);
+
+	return 0;
+}
+
+/*
+ * Support function to axiom_process_u41_report.
+ * Generates input-subsystem events for every target.
+ * After calling this function the caller shall issue
+ * a Sync to the input sub-system.
+ */
+static bool axiom_process_u41_report_target(struct axiom_data *ts,
+					    struct axiom_target_report *target)
+{
+	struct input_dev *input_dev = ts->input_dev;
+	struct axiom_u41_target *target_prev_state;
+	enum axiom_target_state current_state;
+	int id;
+
+	/* Verify the target index */
+	if (target->index >= AXIOM_U41_MAX_TARGETS) {
+		dev_err(ts->dev, "Invalid target index! %u\n", target->index);
+		return false;
+	}
+
+	target_prev_state = &ts->targets[target->index];
+
+	current_state = AXIOM_TARGET_STATE_NOT_PRESENT;
+
+	if (target->present) {
+		if (target->z >= 0)
+			current_state = AXIOM_TARGET_STATE_TOUCHING;
+		else if (target->z > AXIOM_PROX_LEVEL && target->z < 0)
+			current_state = AXIOM_TARGET_STATE_HOVER;
+		else if (target->z == AXIOM_PROX_LEVEL)
+			current_state = AXIOM_TARGET_STATE_PROX;
+	}
+
+	if (target_prev_state->state == current_state &&
+	    target_prev_state->x == target->x &&
+	    target_prev_state->y == target->y &&
+	    target_prev_state->z == target->z)
+		return false;
+
+	id = target->index;
+
+	dev_dbg(ts->dev, "U41 Target T%u, present:%u, x:%u, y:%u, z:%d\n",
+		target->index, target->present,
+		target->x, target->y, target->z);
+
+	switch (current_state) {
+	case AXIOM_TARGET_STATE_NOT_PRESENT:
+	case AXIOM_TARGET_STATE_PROX:
+		if (!target_prev_state->insert)
+			break;
+		target_prev_state->insert = false;
+
+		if (!id)
+			input_report_key(input_dev, BTN_TOUCH, 0);
+
+		input_mt_report_slot_inactive(input_dev);
+		/*
+		 * make sure the previous coordinates are
+		 * all off screen when the finger comes back
+		 */
+		target->x = 65535;
+		target->y = 65535;
+		target->z = AXIOM_PROX_LEVEL;
+		break;
+	case AXIOM_TARGET_STATE_HOVER:
+	case AXIOM_TARGET_STATE_TOUCHING:
+		target_prev_state->insert = true;
+		input_report_abs(input_dev, ABS_MT_TRACKING_ID, id);
+		input_report_abs(input_dev, ABS_MT_POSITION_X, target->x);
+		input_report_abs(input_dev, ABS_MT_POSITION_Y, target->y);
+
+		if (current_state == AXIOM_TARGET_STATE_TOUCHING) {
+			input_report_abs(input_dev, ABS_MT_DISTANCE, 0);
+			input_report_abs(input_dev, ABS_DISTANCE, 0);
+			input_report_abs(input_dev, ABS_MT_PRESSURE, target->z);
+			input_report_abs(input_dev, ABS_PRESSURE, target->z);
+		} else {
+			input_report_abs(input_dev, ABS_MT_DISTANCE, -target->z);
+			input_report_abs(input_dev, ABS_DISTANCE, -target->z);
+			input_report_abs(input_dev, ABS_MT_PRESSURE, 0);
+			input_report_abs(input_dev, ABS_PRESSURE, 0);
+		}
+
+		if (!id)
+			input_report_key(input_dev, BTN_TOUCH, (current_state ==
+					 AXIOM_TARGET_STATE_TOUCHING));
+		break;
+	default:
+		break;
+	}
+
+	target_prev_state->state = current_state;
+	target_prev_state->x = target->x;
+	target_prev_state->y = target->y;
+	target_prev_state->z = target->z;
+
+	return true;
+}
+
+/*
+ * U41 is the output report of the 2D CTS and contains the status of targets
+ * (including contacts and pre-contacts) along with their X,Y,Z values.
+ * When a target has been removed (no longer detected),
+ * the corresponding X,Y,Z values will be zeroed.
+ */
+static bool axiom_process_u41_report(struct axiom_data *ts, u8 *rx_buf)
+{
+	struct axiom_target_report target;
+	bool update_done = false;
+	u16 target_status;
+	int i;
+
+	target_status = get_unaligned_le16(rx_buf + 1);
+
+	for (i = 0; i < AXIOM_U41_MAX_TARGETS; i++) {
+		u8 *target_step = &rx_buf[i * 4];
+
+		target.index = i;
+		input_mt_slot(ts->input_dev, i);
+		input_mt_report_slot_state(ts->input_dev, MT_TOOL_FINGER, true);
+		target.present = ((target_status & (1 << i)) != 0) ? 1 : 0;
+		target.x = get_unaligned_le16(target_step + 3);
+		target.y = get_unaligned_le16(target_step + 5);
+		target.z = (s8)(rx_buf[i + 43]);
+		touchscreen_report_pos(ts->input_dev, &ts->prop, target.x, target.y, true);
+		update_done |= axiom_process_u41_report_target(ts, &target);
+	}
+
+	return update_done;
+}
+
+/*
+ * U46 report contains a low level measurement data generated by the capacitive
+ * displacement sensor (CDS) algorithms from the auxiliary channels.
+ * This information is useful when tuning multi-press to assess mechanical
+ * consistency in the unit's construction.
+ */
+static void axiom_process_u46_report(struct axiom_data *ts, u8 *rx_buf)
+{
+	struct input_dev *input_dev = ts->input_dev;
+	u32 event_value;
+	u16 aux_value;
+	int i;
+
+	for (i = 0; i < AXIOM_U46_AUX_CHANNELS; i++) {
+		u8 *target_step = &rx_buf[i * 2];
+
+		input_mt_slot(input_dev, i);
+		input_mt_report_slot_state(input_dev, MT_TOOL_FINGER, true);
+		aux_value = get_unaligned_le16(target_step + 1) & AXIOM_U46_AUX_MASK;
+		event_value = (i << 16) | (aux_value);
+		input_event(input_dev, EV_MSC, MSC_RAW, event_value);
+	}
+}
+
+/*
+ * Validates the crc and demultiplexes the axiom reports to the appropriate
+ * report handler
+ */
+static int axiom_handle_events(struct axiom_data *ts)
+{
+	struct input_dev *input_dev = ts->input_dev;
+	u8 *report_data = ts->rx_buf;
+	struct device *dev = ts->dev;
+	u16 crc_report;
+	u8 *crc_bytes;
+	u16 crc_calc;
+	int error;
+	u8 len;
+
+	error = axiom_read(ts, AXIOM_REPORT_USAGE_ID, 0, report_data, ts->max_report_len);
+	if (error)
+		return error;
+
+	len = (report_data[0] & AXIOM_COMMS_REPORT_LEN_MASK) << 1;
+	if (len <= 2) {
+		dev_err(dev, "Zero length report discarded.\n");
+		return -ENODATA;
+	}
+
+	/* Validate the report CRC */
+	crc_bytes = &report_data[len];
+
+	crc_report = get_unaligned_le16(crc_bytes - 2);
+	/* Length is in 16 bit words and remove the size of the CRC16 itself */
+	crc_calc = crc16(0, report_data, (len - 2));
+
+	if (crc_calc != crc_report) {
+		dev_err(dev,
+			"CRC mismatch! Expected: %#x, Calculated CRC: %#x.\n",
+			crc_report, crc_calc);
+		return -EINVAL;
+	}
+
+	switch (report_data[1]) {
+	case AXIOM_USAGE_2DCTS_REPORT_ID:
+		if (axiom_process_u41_report(ts, &report_data[1])) {
+			input_mt_sync_frame(input_dev);
+			input_sync(input_dev);
+		}
+		break;
+
+	case AXIOM_USAGE_2AUX_REPORT_ID:
+		/* This is an aux report (force) */
+		axiom_process_u46_report(ts, &report_data[1]);
+		input_mt_sync(input_dev);
+		input_sync(input_dev);
+		break;
+
+	case AXIOM_USAGE_2HB_REPORT_ID:
+		/* This is a heartbeat report */
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void axiom_i2c_poll(struct input_dev *input_dev)
+{
+	struct axiom_data *ts = input_get_drvdata(input_dev);
+
+	axiom_handle_events(ts);
+}
+
+static irqreturn_t axiom_irq(int irq, void *dev_id)
+{
+	struct axiom_data *ts = dev_id;
+
+	axiom_handle_events(ts);
+
+	return IRQ_HANDLED;
+}
+
+static void axiom_reset(struct gpio_desc *reset_gpio)
+{
+	gpiod_set_value_cansleep(reset_gpio, 1);
+	usleep_range(1000, 2000);
+	gpiod_set_value_cansleep(reset_gpio, 0);
+	msleep(AXIOM_STARTUP_TIME_MS);
+}
+
+static int axiom_i2c_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct input_dev *input_dev;
+	struct axiom_data *ts;
+	u32 poll_interval;
+	int target;
+	int error;
+
+	ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, ts);
+	ts->client = client;
+	ts->dev = dev;
+
+	ts->regmap = devm_regmap_init_i2c(client, &axiom_i2c_regmap_config);
+	error = PTR_ERR_OR_ZERO(ts->regmap);
+	if (error) {
+		dev_err(dev, "Failed to initialize regmap: %d\n", error);
+		return error;
+	}
+
+	error = devm_regulator_get_enable(dev, "vddi");
+	if (error)
+		return dev_err_probe(&client->dev, error,
+				     "Failed to enable VDDI regulator\n");
+
+	error = devm_regulator_get_enable(dev, "vdda");
+	if (error)
+		return dev_err_probe(&client->dev, error,
+				     "Failed to enable VDDA regulator\n");
+
+	ts->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(ts->reset_gpio))
+		return dev_err_probe(dev, PTR_ERR(ts->reset_gpio), "failed to get reset GPIO\n");
+
+	if (ts->reset_gpio)
+		axiom_reset(ts->reset_gpio);
+	else
+		msleep(AXIOM_STARTUP_TIME_MS);
+
+	error = axiom_discover(ts);
+	if (error)
+		return dev_err_probe(dev, error, "Failed touchscreen discover\n");
+
+	input_dev = devm_input_allocate_device(ts->dev);
+	if (!input_dev)
+		return -ENOMEM;
+
+	input_dev->name = "TouchNetix axiom Touchscreen";
+	input_dev->phys = "input/axiom_ts";
+
+	input_set_abs_params(input_dev, ABS_MT_POSITION_X, 0, 65535, 0, 0);
+	input_set_abs_params(input_dev, ABS_MT_POSITION_Y, 0, 65535, 0, 0);
+	input_set_abs_params(input_dev, ABS_MT_TOOL_TYPE, 0, MT_TOOL_MAX, 0, 0);
+	input_set_abs_params(input_dev, ABS_MT_DISTANCE, 0, 127, 0, 0);
+	input_set_abs_params(input_dev, ABS_MT_PRESSURE, 0, 127, 0, 0);
+
+	touchscreen_parse_properties(input_dev, true, &ts->prop);
+
+	/* Registers the axiom device as a touchscreen instead of a mouse pointer */
+	error = input_mt_init_slots(input_dev, AXIOM_U41_MAX_TARGETS, INPUT_MT_DIRECT);
+	if (error)
+		return error;
+
+	/* Enables the raw data for up to 4 force channels to be sent to the input subsystem */
+	set_bit(EV_REL, input_dev->evbit);
+	set_bit(EV_MSC, input_dev->evbit);
+	/* Declare that we support "RAW" Miscellaneous events */
+	set_bit(MSC_RAW, input_dev->mscbit);
+
+	ts->input_dev = input_dev;
+	input_set_drvdata(ts->input_dev, ts);
+
+	/* Ensure that all reports are initialised to not be present. */
+	for (target = 0; target < AXIOM_U41_MAX_TARGETS; target++)
+		ts->targets[target].state = AXIOM_TARGET_STATE_NOT_PRESENT;
+
+	error = devm_request_threaded_irq(dev, client->irq, NULL,
+					  axiom_irq, IRQF_ONESHOT, dev_name(dev), ts);
+	if (error) {
+		dev_info(dev, "Request irq failed, falling back to polling mode");
+
+		error = input_setup_polling(input_dev, axiom_i2c_poll);
+		if (error)
+			return dev_err_probe(ts->dev, error, "Unable to set up polling mode\n");
+
+		if (!device_property_read_u32(ts->dev, "poll-interval", &poll_interval))
+			input_set_poll_interval(input_dev, poll_interval);
+		else
+			input_set_poll_interval(input_dev, POLL_INTERVAL_DEFAULT_MS);
+	}
+
+	return input_register_device(input_dev);
+}
+
+static const struct i2c_device_id axiom_i2c_id_table[] = {
+	{ "ax54a" },
+	{ },
+};
+MODULE_DEVICE_TABLE(i2c, axiom_i2c_id_table);
+
+static const struct of_device_id axiom_i2c_of_match[] = {
+	{ .compatible = "touchnetix,ax54a", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, axiom_i2c_of_match);
+
+static struct i2c_driver axiom_i2c_driver = {
+	.driver = {
+		   .name = "axiom",
+		   .of_match_table = axiom_i2c_of_match,
+	},
+	.id_table = axiom_i2c_id_table,
+	.probe = axiom_i2c_probe,
+};
+module_i2c_driver(axiom_i2c_driver);
+
+MODULE_AUTHOR("Bart Prescott <bartp@baasheep.co.uk>");
+MODULE_AUTHOR("Pedro Torruella <pedro.torruella@touchnetix.com>");
+MODULE_AUTHOR("Mark Satterthwaite <mark.satterthwaite@touchnetix.com>");
+MODULE_AUTHOR("Hannah Rossiter <hannah.rossiter@touchnetix.com>");
+MODULE_AUTHOR("Kamel Bouhara <kamel.bouhara@bootlin.com>");
+MODULE_DESCRIPTION("TouchNetix axiom touchscreen I2C bus driver");
+MODULE_LICENSE("GPL");
-- 
2.25.1