Re: [PATCH v2 2/3] Input: Add Novatek NT36xxx touchscreen driver

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi AngeloGioacchino,

On Sun, Sep 27, 2020 at 02:35:41PM +0200, kholk11@gmail.com wrote:
> From: AngeloGioacchino Del Regno <kholk11@gmail.com>
> 
> This is a driver for the Novatek in-cell touch controller and
> supports various chips from the NT36xxx family, currently
> including NT36525, NT36672A, NT36676F, NT36772 and NT36870.
> 
> Functionality like wake gestures and firmware flashing is not
> included: I am not aware of any of these DrIC+Touch combo
> chips not including a non-volatile memory and it should be
> highly unlikely to find one, since the touch firmware is
> embedded into the DriverIC one, which is obviously necessary
> to drive the display unit.
> 
> However, the necessary address for the firmware update
> procedure was included into the address table in this driver
> so, in the event that someone finds the need to implement it
> for a reason or another, it will be pretty straightforward to.
> 
> This driver is lightly based on the downstream implementation [1].
> [1] https://github.com/Rasenkai/caf-tsoft-Novatek-nt36xxx
> 
> Signed-off-by: AngeloGioacchino Del Regno <kholk11@gmail.com>
> ---
>  drivers/input/touchscreen/Kconfig   |  12 +
>  drivers/input/touchscreen/Makefile  |   1 +
>  drivers/input/touchscreen/nt36xxx.c | 742 ++++++++++++++++++++++++++++
>  drivers/input/touchscreen/nt36xxx.h | 122 +++++
>  4 files changed, 877 insertions(+)
>  create mode 100644 drivers/input/touchscreen/nt36xxx.c
>  create mode 100644 drivers/input/touchscreen/nt36xxx.h
> 
> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> index 35c867b2d9a7..6d118b967021 100644
> --- a/drivers/input/touchscreen/Kconfig
> +++ b/drivers/input/touchscreen/Kconfig
> @@ -605,6 +605,18 @@ config TOUCHSCREEN_MTOUCH
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called mtouch.
>  
> +config TOUCHSCREEN_NT36XXX
> +	tristate "Novatek NT36XXX In-Cell I2C touchscreen controller"
> +	depends on I2C
> +	help
> +	  Say Y here if you have a Novatek NT36xxx series In-Cell
> +	  touchscreen connected to your system over I2C.
> +
> +	  If unsure, say N.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called nt36xxx.
> +
>  config TOUCHSCREEN_IMX6UL_TSC
>  	tristate "Freescale i.MX6UL touchscreen controller"
>  	depends on (OF && GPIOLIB) || COMPILE_TEST
> diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
> index 30d1e1b42492..424a555e03d5 100644
> --- a/drivers/input/touchscreen/Makefile
> +++ b/drivers/input/touchscreen/Makefile
> @@ -61,6 +61,7 @@ obj-$(CONFIG_TOUCHSCREEN_MIGOR)		+= migor_ts.o
>  obj-$(CONFIG_TOUCHSCREEN_MMS114)	+= mms114.o
>  obj-$(CONFIG_TOUCHSCREEN_MTOUCH)	+= mtouch.o
>  obj-$(CONFIG_TOUCHSCREEN_MK712)		+= mk712.o
> +obj-$(CONFIG_TOUCHSCREEN_NT36XXX)	+= nt36xxx.o
>  obj-$(CONFIG_TOUCHSCREEN_HP600)		+= hp680_ts_input.o
>  obj-$(CONFIG_TOUCHSCREEN_HP7XX)		+= jornada720_ts.o
>  obj-$(CONFIG_TOUCHSCREEN_IPAQ_MICRO)	+= ipaq-micro-ts.o
> diff --git a/drivers/input/touchscreen/nt36xxx.c b/drivers/input/touchscreen/nt36xxx.c
> new file mode 100644
> index 000000000000..57e189938d12
> --- /dev/null
> +++ b/drivers/input/touchscreen/nt36xxx.c
> @@ -0,0 +1,742 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2010 - 2017 Novatek, Inc.
> + * Copyright (C) 2020 AngeloGioacchino Del Regno <kholk11@gmail.com>
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/of_gpio.h>

Is this needed?

> +#include <linux/input/mt.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include "nt36xxx.h"
> +
> +static const struct nt36xxx_mem_map nt36xxx_memory_maps[] = {
> +	[NT36525_IC]  = { 0x11a00, 0x10000, 0x12000, 0x14000, 0x14002 },
> +	[NT36672A_IC] = { 0x21c00, 0x20000, 0x23000, 0x24000, 0x24002 },
> +	[NT36676F_IC] = { 0x11a00, 0x10000, 0x12000, 0x14000, 0x14002 },
> +	[NT36772_IC]  = { 0x11e00, 0x10000, 0x12000, 0x14000, 0x14002 },
> +	[NT36870_IC]  = { 0x25000, 0x20000, 0x23000, 0x24000, 0x24002 },
> +};
> +
> +static const struct nt36xxx_trim_table trim_id_table[] = {
> +	{
> +	 .id = { 0x0A, 0xFF, 0xFF, 0x72, 0x66, 0x03 },
> +	 .mask = { 1, 0, 0, 1, 1, 1 },
> +	 .mapid = NT36672A_IC,
> +	},
> +	{
> +	 .id = { 0x55, 0x00, 0xFF, 0x00, 0x00, 0x00 },
> +	 .mask = { 1, 1, 0, 1, 1, 1 },
> +	 .mapid = NT36772_IC,
> +	},
> +	{
> +	 .id = { 0x55, 0x72, 0xFF, 0x00, 0x00, 0x00 },
> +	 .mask = { 1, 1, 0, 1, 1, 1 },
> +	 .mapid = NT36772_IC,
> +	},
> +	{
> +	 .id = { 0xAA, 0x00, 0xFF, 0x00, 0x00, 0x00 },
> +	 .mask = { 1, 1, 0, 1, 1, 1 },
> +	 .mapid = NT36772_IC,
> +	},
> +	{
> +	 .id = { 0xAA, 0x72, 0xFF, 0x00, 0x00, 0x00 },
> +	 .mask = { 1, 1, 0, 1, 1, 1 },
> +	 .mapid = NT36772_IC,
> +	},
> +	{
> +	 .id = { 0xFF, 0xFF, 0xFF, 0x72, 0x67, 0x03 },
> +	 .mask = { 0, 0, 0, 1, 1, 1 },
> +	 .mapid = NT36772_IC,
> +	},
> +	{
> +	 .id = { 0xFF, 0xFF, 0xFF, 0x70, 0x66, 0x03 },
> +	 .mask = { 0, 0, 0, 1, 1, 1 },
> +	 .mapid = NT36772_IC,
> +	},
> +	{
> +	 .id = { 0xFF, 0xFF, 0xFF, 0x70, 0x67, 0x03 },
> +	 .mask = { 0, 0, 0, 1, 1, 1 },
> +	 .mapid = NT36772_IC,
> +	},
> +	{
> +	 .id = { 0xFF, 0xFF, 0xFF, 0x72, 0x66, 0x03 },
> +	 .mask = { 0, 0, 0, 1, 1, 1 },
> +	 .mapid = NT36772_IC,
> +	},
> +	{
> +	 .id = { 0xFF, 0xFF, 0xFF, 0x25, 0x65, 0x03 },
> +	 .mask = { 0, 0, 0, 1, 1, 1 },
> +	 .mapid = NT36772_IC,
> +	},
> +	{
> +	 .id = { 0xFF, 0xFF, 0xFF, 0x70, 0x68, 0x03 },
> +	 .mask = { 0, 0, 0, 1, 1, 1 },
> +	 .mapid = NT36772_IC,
> +	},
> +	{
> +	 .id = { 0xFF, 0xFF, 0xFF, 0x76, 0x66, 0x03 },
> +	 .mask = { 0, 0, 0, 1, 1, 1 },
> +	 .mapid = NT36676F_IC,
> +	},
> +};
> +
> +static int nt36xxx_read(struct i2c_client *client, uint16_t address,

Please use shorthand - u16 - in kernel.

> +			u8 *buf, uint16_t len)
> +{
> +	int ret, retry = NT36XXX_MAX_RETRIES;
> +	struct i2c_msg msg[] = {
> +		/* Write slave position to i2c devices */
> +		{
> +			.addr = address,
> +			.len = 1,
> +			.buf = &buf[0]
> +		},
> +		/* Read data from position */
> +		{
> +			.addr = address,
> +			.flags = I2C_M_RD,
> +			.len = len - 1,
> +			.buf = &buf[1]
> +		}
> +	};
> +
> +	do {
> +		ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
> +		if (likely(ret == ARRAY_SIZE(msg)))
> +			return 0;
> +	} while (--retry);
> +
> +	return ret < 0 ? ret : -EIO;
> +}
> +
> +static int nt36xxx_write(struct i2c_client *client, uint16_t address,
> +			 u8 *buf, uint16_t len)
> +{
> +	int ret, retry = NT36XXX_MAX_RETRIES;
> +	struct i2c_msg msg[] = {
> +		{
> +			.addr = address,
> +			.flags = 0,
> +			.len = len,
> +			.buf = buf,
> +		},
> +	};
> +
> +	do {
> +		ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
> +		if (likely(ret == ARRAY_SIZE(msg)))
> +			return 0;
> +
> +		usleep_range(100, 200);
> +	} while (--retry);
> +
> +	return ret < 0 ? ret : -EIO;
> +}
> +
> +static int nt36xxx_set_page(struct nt36xxx_i2c *ts, uint32_t pageaddr)
> +{
> +	u8 buf[3];
> +
> +	buf[0] = NT36XXX_CMD_SET_PAGE;
> +	buf[1] = (pageaddr >> 16) & 0xFF;
> +	buf[2] = (pageaddr >> 8) & 0xFF;
> +
> +	return nt36xxx_write(ts->client, NT36XXX_BLDR_ADDR, buf, 3);

Sounds like regmap is a good option to be used here.

> +}
> +
> +static int nt36xxx_sw_reset_idle(struct nt36xxx_i2c *ts)
> +{
> +	u8 buf[] = { 0x00, NT36XXX_CMD_SW_RESET };
> +	int ret;
> +
> +	ret = nt36xxx_write(ts->client, ts->client->addr,
> +			    buf, ARRAY_SIZE(buf));
> +
> +	usleep_range(15000, 16000);
> +	return ret;
> +}
> +
> +static int nt36xxx_bootloader_reset(struct nt36xxx_i2c *ts)
> +{
> +	u8 buf[] = { 0x00, NT36XXX_CMD_BOOTLOADER_RESET };
> +	int ret;
> +
> +	ret = nt36xxx_write(ts->client, ts->client->addr,
> +			    buf, ARRAY_SIZE(buf));
> +
> +	msleep(35);
> +	return ret;
> +}
> +
> +static int nt36xxx_check_reset_state(struct nt36xxx_i2c *ts,
> +				     enum nt36xxx_fw_state fw_state)
> +{
> +	u8 buf[6] = { NT36XXX_EVT_RESET_COMPLETE, 0x00, 0x00,
> +			   0x00, 0x00, 0x00 };
> +	int ret, retry = NT36XXX_MAX_FW_RST_RETRY;
> +
> +	do {
> +		ret = nt36xxx_read(ts->client, NT36XXX_BLDR_ADDR, buf, 6);
> +		if (likely(ret != -EIO) &&
> +		    (buf[1] >= fw_state) &&
> +		    (buf[1] <= NT36XXX_STATE_MAX)) {
> +			ret = 0;
> +			break;
> +		}
> +		usleep_range(10000, 11000);
> +	} while (--retry);
> +
> +	if (!retry) {
> +		dev_err(&ts->client->dev, "Firmware reset failed.\n");
> +		ret = -EBUSY;
> +	}
> +
> +	return ret;
> +}
> +
> +static int nt36xxx_read_pid(struct nt36xxx_i2c *ts)
> +{
> +	u8 buf[] = { NT36XXX_EVT_PROJECTID, 0x00, 0x00 };
> +	int ret = 0;
> +
> +	ret = nt36xxx_set_page(ts, ts->mmap->evtbuf_addr);
> +	if (unlikely(ret < 0))
> +		return ret;
> +
> +	/* Read project id */
> +	ret = nt36xxx_read(ts->client, NT36XXX_BLDR_ADDR,
> +			   buf, ARRAY_SIZE(buf));
> +	if (unlikely(ret < 0))
> +		return ret;
> +
> +	ts->fw_info.nvt_pid = (buf[2] << 8) + buf[1];
> +
> +	return 0;
> +}
> +
> +static int __nt36xxx_get_fw_info(struct nt36xxx_i2c *ts)
> +{
> +	struct nt36xxx_fw_info *fwi = &ts->fw_info;
> +	u8 buf[17] = { 0 };
> +	int ret = 0;
> +
> +	ret = nt36xxx_set_page(ts, ts->mmap->evtbuf_addr);
> +	if (unlikely(ret < 0))
> +		return ret;
> +
> +	/* Read fw info */
> +	buf[0] = NT36XXX_EVT_FWINFO;
> +	nt36xxx_read(ts->client, NT36XXX_BLDR_ADDR, buf, 17);
> +	fwi->fw_ver = buf[1];
> +	fwi->x_num = buf[3];
> +	fwi->y_num = buf[4];
> +	fwi->abs_x_max = (uint16_t)((buf[5] << 8) | buf[6]);
> +	fwi->abs_y_max = (uint16_t)((buf[7] << 8) | buf[8]);
> +	fwi->max_buttons = buf[11];
> +
> +	/* Check fw info integrity and clear x_num, y_num if broken */
> +	if ((buf[1] + buf[2]) != 0xFF) {
> +		dev_dbg(&ts->client->dev,
> +			"FW info is broken! fw_ver=0x%02X, ~fw_ver=0x%02X\n",
> +			buf[1], buf[2]);
> +		fwi->fw_ver = 0;
> +		fwi->x_num = 18;
> +		fwi->y_num = 32;
> +		fwi->abs_x_max = TOUCH_DEFAULT_MAX_WIDTH;
> +		fwi->abs_y_max = TOUCH_DEFAULT_MAX_HEIGHT;
> +		fwi->max_buttons = 0;
> +		return -EINVAL;
> +	}
> +
> +	/* Get Novatek ProjectID */
> +	return nt36xxx_read_pid(ts);
> +}
> +
> +static int nt36xxx_get_fw_info(struct nt36xxx_i2c *ts)
> +{
> +	struct nt36xxx_fw_info *fwi = &ts->fw_info;
> +	int i, ret = 0;
> +
> +	for (i = 0; i < NT36XXX_MAX_RETRIES; i++) {
> +		ret = __nt36xxx_get_fw_info(ts);
> +		if (ret == 0)
> +			break;
> +	}
> +
> +	dev_dbg(&ts->client->dev,
> +		"Firmware Info: ver=0x%x res=%ux%u max=%ux%u buttons=%u",
> +		fwi->fw_ver, fwi->x_num, fwi->y_num,
> +		fwi->abs_x_max, fwi->abs_y_max, fwi->max_buttons);
> +
> +	return ret;
> +}
> +
> +static void nt36xxx_i2c_work_func(struct work_struct *work)
> +{
> +	struct nt36xxx_i2c *ts = container_of(work, struct nt36xxx_i2c, ts_work);
> +	struct nt36xxx_abs_object *obj = &ts->abs_obj;
> +	struct input_dev *input = ts->input;
> +	u8 input_id = 0;
> +	u8 press_id[TOUCH_MAX_FINGER_NUM] = { 0 };
> +	u8 point[POINT_DATA_LEN + 1] = { 0 };
> +	unsigned int ppos = 0;
> +	int i, ret, finger_cnt = 0;
> +
> +	mutex_lock(&ts->lock);
> +
> +	ret = nt36xxx_read(ts->client, NT36XXX_BLDR_ADDR, point,
> +			   POINT_DATA_LEN + 1);

Is the chip even no in bootloader mode? I only see transfers to
NT36XXX_BLDR_ADDR...

> +	if (unlikely(ret < 0)) {
> +		dev_dbg(&ts->client->dev,
> +			"Cannot read touch point data: %d\n", ret);
> +		goto xfer_error;
> +	}
> +
> +	for (i = 0; i < ts->max_fingers; i++) {
> +		ppos = 1 + 6 * i;
> +		input_id = point[ppos + 0] >> 3;
> +		if ((input_id == 0) || (input_id > ts->max_fingers))
> +			continue;
> +
> +		if (((point[ppos] & 0x07) == 0x01) ||
> +		    ((point[ppos] & 0x07) == 0x02)) {
> +			obj->x = (point[ppos + 1] << 4) +
> +				 (point[ppos + 3] >> 4);
> +			obj->y = (point[ppos + 2] << 4) +
> +				 (point[ppos + 3] & 0xf);
> +			if ((obj->x > ts->fw_info.abs_x_max) ||
> +			    (obj->y > ts->fw_info.abs_y_max))
> +				continue;
> +
> +			obj->tm = point[ppos + 4];
> +			if (obj->tm == 0)
> +				obj->tm = 1;
> +
> +			obj->z = point[ppos + 5];
> +			if (i < 2) {
> +				obj->z += point[i + 63] << 8;
> +				if (obj->z > TOUCH_MAX_PRESSURE)
> +					obj->z = TOUCH_MAX_PRESSURE;
> +			}
> +
> +			if (obj->z == 0)
> +				obj->z = 1;
> +
> +			press_id[input_id - 1] = 1;
> +			input_mt_slot(input, input_id - 1);
> +			input_mt_report_slot_state(input,
> +						   MT_TOOL_FINGER, true);
> +
> +			input_report_abs(input, ABS_MT_POSITION_X, obj->x);
> +			input_report_abs(input, ABS_MT_POSITION_Y, obj->y);
> +			input_report_abs(input, ABS_MT_TOUCH_MAJOR, obj->tm);
> +			input_report_abs(input, ABS_MT_PRESSURE, obj->z);
> +
> +			finger_cnt++;
> +		}
> +	}
> +
> +	for (i = 0; i < ts->max_fingers; i++) {
> +		if (press_id[i] != 1) {
> +			input_mt_slot(input, i);
> +			input_report_abs(input, ABS_MT_TOUCH_MAJOR, 0);
> +			input_report_abs(input, ABS_MT_PRESSURE, 0);
> +			input_mt_report_slot_state(input,
> +						   MT_TOOL_FINGER, false);

I think INPUT_MT_TRACK_UNUSED will help here.

> +		}
> +	}
> +
> +	input_report_key(input, BTN_TOUCH, (finger_cnt > 0));
> +
> +	input_sync(input);
> +
> +xfer_error:
> +	enable_irq(ts->client->irq);
> +
> +	mutex_unlock(&ts->lock);
> +}
> +
> +static irqreturn_t nt36xxx_i2c_irq_handler(int irq, void *dev_id)
> +{
> +	struct nt36xxx_i2c *ts = dev_id;
> +
> +	disable_irq_nosync(ts->client->irq);
> +	queue_work(ts->ts_workq, &ts->ts_work);

You are using threaded interrupt, there is no need to involve workqueue
here.

> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int nvt_stop_crc_reboot(struct nt36xxx_i2c *ts)
> +{
> +	u8 buf[4] = { 0 };
> +	int ret, retry = NT36XXX_MAX_RETRIES;
> +
> +	/* Read dummy buffer to check CRC fail reboot is happening or not */
> +
> +	/* Change I2C index to prevent geting 0xFF, but not 0xFC */
> +	ret = nt36xxx_set_page(ts, NT36XXX_PAGE_CHIP_INFO);
> +	if (ret < 0) {
> +		dev_dbg(&ts->client->dev,
> +			"CRC reset failed: Cannot select page.\n");
> +		return ret;
> +	}
> +
> +	/* Read to check if buf is 0xFC which means IC is in CRC reboot */
> +	buf[0] = 0x4E;
> +	ret = nt36xxx_read(ts->client, NT36XXX_BLDR_ADDR, buf, 3);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (((buf[1] == 0xFC) && (buf[2] == 0xFC) && (buf[3] == 0xFC)) ||
> +	    ((buf[1] == 0xFF) && (buf[2] == 0xFF) && (buf[3] == 0xFF))) {
> +		/* IC is in CRC fail reboot loop, needs to be stopped! */
> +		do {
> +			/* Write i2c cmds to reset idle - part #1 */
> +			buf[0] = 0x00;
> +			buf[1] = 0xA5;
> +			nt36xxx_write(ts->client, ts->client->addr,
> +				      buf, 2);
> +
> +			/* Write i2c cmds to reset idle - part #2 */
> +			buf[0] = 0x00;
> +			buf[1] = 0xA5;
> +			nt36xxx_write(ts->client, ts->client->addr,
> +				      buf, 2);
> +			usleep_range(1000, 1100);
> +
> +			/* Clear CRC_ERR_FLAG */
> +			ret = nt36xxx_set_page(ts, NT36XXX_PAGE_CRC);
> +			if (ret < 0)
> +				continue;
> +
> +			buf[0] = 0x35;
> +			buf[1] = 0xA5;
> +			nt36xxx_write(ts->client, NT36XXX_BLDR_ADDR, buf, 2);
> +
> +			/* Check CRC_ERR_FLAG */
> +			ret = nt36xxx_set_page(ts, NT36XXX_PAGE_CRC);
> +			if (ret < 0)
> +				continue;
> +
> +			buf[0] = 0x35;
> +			buf[1] = 0x00;
> +			nt36xxx_read(ts->client, NT36XXX_BLDR_ADDR, buf, 2);
> +
> +			if (buf[1] == 0xA5)
> +				break;
> +		} while (--retry);
> +
> +		if (retry == 0) {
> +			dev_err(&ts->client->dev,
> +				"CRC reset failed: buf[1]=0x%02X\n", buf[1]);
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int nt36xxx_i2c_chip_version_init(struct nt36xxx_i2c *ts)
> +{
> +	u8 buf[7] = { 0 };
> +	int retry = NT36XXX_MAX_RETRIES;
> +	int sz = sizeof(trim_id_table) / sizeof(struct nt36xxx_trim_table);
> +	int i, list, mapid, ret;
> +
> +	ret = nt36xxx_bootloader_reset(ts);
> +	if (ret < 0) {
> +		dev_err(&ts->client->dev, "Can't reset the nvt IC\n");
> +		return ret;
> +	}
> +
> +	do {
> +		ret = nt36xxx_sw_reset_idle(ts);
> +		if (ret < 0)
> +			continue;
> +
> +		buf[0] = 0x00;
> +		buf[1] = NT36XXX_CMD_UNLOCK;
> +		nt36xxx_write(ts->client, ts->client->addr, buf, 2);
> +		usleep_range(10000, 11000);
> +
> +		ret = nt36xxx_set_page(ts, NT36XXX_PAGE_CHIP_INFO);
> +		if (ret < 0)
> +			continue;
> +
> +		memset(buf, 0, ARRAY_SIZE(buf));
> +		buf[0] = NT36XXX_EVT_CHIPID;
> +		nt36xxx_read(ts->client, NT36XXX_BLDR_ADDR, buf, 7);
> +
> +		/* Compare read chip id with trim list */
> +		for (list = 0; list < sz; list++) {
> +			/* Compare each not masked byte */
> +			for (i = 0; i < NT36XXX_ID_LEN_MAX; i++) {
> +				if (trim_id_table[list].mask[i] &&
> +				    buf[i + 1] != trim_id_table[list].id[i])
> +					break;
> +			}
> +
> +			if (i == NT36XXX_ID_LEN_MAX) {
> +				mapid = trim_id_table[list].mapid;
> +				ts->mmap = &nt36xxx_memory_maps[mapid];
> +				return 0;
> +			}
> +
> +			ts->mmap = NULL;
> +			ret = -ENOENT;
> +		}
> +
> +		/* Stop CRC check to prevent IC auto reboot */
> +		if (((buf[1] == 0xFC) && (buf[2] == 0xFC) &&
> +		     (buf[3] == 0xFC)) ||
> +		    ((buf[1] == 0xFF) && (buf[2] == 0xFF) &&
> +		     (buf[3] == 0xFF))) {
> +			ret = nvt_stop_crc_reboot(ts);
> +			if (ret < 0)
> +				continue;
> +		}
> +
> +		usleep_range(10000, 11000);
> +	} while (--retry);
> +
> +	return ret;
> +}
> +
> +static int nt36xxx_i2c_probe(struct i2c_client *client,
> +			     const struct i2c_device_id *id)
> +{
> +	struct nt36xxx_i2c *ts;
> +	struct input_dev *input;
> +	int ret;
> +
> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
> +		dev_err(&client->dev, "i2c_check_functionality error\n");
> +		return -EIO;
> +	}
> +
> +	if (!client->irq) {
> +		dev_err(&client->dev, "No irq specified\n");
> +		return -EINVAL;
> +	}
> +
> +	ts = devm_kzalloc(&client->dev, sizeof(struct nt36xxx_i2c), GFP_KERNEL);
> +	if (!ts)
> +		return -ENOMEM;
> +
> +	ts->supplies = devm_kcalloc(&client->dev,
> +				    NT36XXX_NUM_SUPPLIES,
> +				    sizeof(struct regulator_bulk_data),
> +				    GFP_KERNEL);
> +	if (!ts->supplies)
> +		return -ENOMEM;
> +
> +	input = devm_input_allocate_device(&client->dev);
> +	if (!input)
> +		return -ENOMEM;
> +
> +	ts->client = client;
> +	ts->input = input;
> +	i2c_set_clientdata(client, ts);
> +
> +	ts->ts_workq = alloc_ordered_workqueue("nt36xxx", 0);
> +	if (!ts->ts_workq)
> +		return -EINVAL;
> +
> +	ts->reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
> +						 GPIOD_OUT_HIGH);
> +	if (IS_ERR(ts->reset_gpio))
> +		return PTR_ERR(ts->reset_gpio);
> +	if (ts->reset_gpio)
> +		gpiod_set_consumer_name(ts->reset_gpio, "nt36xxx reset");
> +
> +	/* These supplies are optional */
> +	ts->supplies[0].supply = "vdd";
> +	ts->supplies[1].supply = "vio";
> +	ret = devm_regulator_bulk_get(&client->dev,
> +				      NT36XXX_NUM_SUPPLIES,
> +				      ts->supplies);
> +	if (ret != 0) {
> +		if (ret != -EPROBE_DEFER)
> +			dev_err(&client->dev, "Cannot get supplies: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = regulator_bulk_enable(NT36XXX_NUM_SUPPLIES, ts->supplies);
> +	if (ret)
> +		return ret;
> +
> +	usleep_range(10000, 11000);
> +
> +	mutex_init(&ts->lock);
> +
> +	ret = nt36xxx_i2c_chip_version_init(ts);
> +	if (ret) {
> +		dev_err(&client->dev, "Failed to check chip version\n");
> +		goto error;
> +	}
> +
> +	mutex_lock(&ts->lock);
> +	ret = nt36xxx_bootloader_reset(ts);
> +	ret += nt36xxx_check_reset_state(ts, NT36XXX_STATE_INIT);
> +	ret += nt36xxx_get_fw_info(ts);
> +	mutex_unlock(&ts->lock);

What are you protecting here with this mutex?

> +	if (unlikely(ret < 0))
> +		goto error;
> +
> +	ts->max_fingers = TOUCH_MAX_FINGER_NUM;
> +	INIT_WORK(&ts->ts_work, nt36xxx_i2c_work_func);
> +
> +	input->phys = devm_kasprintf(&client->dev, GFP_KERNEL,
> +				     "%s/input0", dev_name(&client->dev));
> +
> +	input->name = NT36XXX_INPUT_DEVICE_NAME;
> +	input->id.bustype = BUS_I2C;
> +	input->dev.parent = &client->dev;
> +
> +	input->evbit[0] =
> +		BIT_MASK(EV_SYN) | BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);

No need to set EV_SYN.

> +	input->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);

	input_set_capability(input, EV_KEY, BTN_TOUCH);

> +	input->propbit[0] = BIT(INPUT_PROP_DIRECT);

Please use __set_bit().

> +
> +	input_mt_init_slots(input, ts->max_fingers, 0);

You need to add error handling and some flags here.

> +	input_set_abs_params(input, ABS_MT_PRESSURE, 0,
> +			     TOUCH_MAX_PRESSURE, 0, 0);
> +
> +	if (ts->max_fingers > 1) {
> +		input_set_abs_params(input, ABS_MT_TOUCH_MAJOR, 0, 255, 0, 0);
> +
> +		input_set_abs_params(input, ABS_MT_POSITION_X, 0,
> +				     ts->fw_info.abs_x_max - 1, 0, 0);
> +		input_set_abs_params(input, ABS_MT_POSITION_Y, 0,
> +				     ts->fw_info.abs_y_max - 1, 0, 0);
> +	}

Please use API from include/linux/input/touchscreen.h to enable basic
transformations.

> +
> +	input_set_drvdata(input, ts);
> +
> +	ret = input_register_device(ts->input);
> +	if (ret) {
> +		dev_err(&client->dev, "Failed to register input device: %d\n",
> +			ret);
> +		goto error;
> +	}
> +
> +	ret = devm_request_threaded_irq(&client->dev, client->irq, NULL,
> +					nt36xxx_i2c_irq_handler, IRQF_ONESHOT,
> +					client->name, ts);
> +	if (ret != 0) {
> +		dev_err(&client->dev, "request irq failed: %d\n", ret);
> +		goto intr_error;
> +	}
> +
> +	disable_irq(client->irq);
> +	device_init_wakeup(&client->dev, 1);

Rely on DT and I2C core to set up device for wakeup.

> +	enable_irq(client->irq);

Why?

> +
> +	return 0;
> +
> +intr_error:
> +	input_unregister_device(ts->input);

You are using managed input device, no need to unregister explicitly.

> +error:
> +	regulator_bulk_disable(NT36XXX_NUM_SUPPLIES, ts->supplies);

Please install as custom devm action (devm_add_action_or_reset).

> +	return ret;
> +}
> +
> +static int nt36xxx_i2c_remove(struct i2c_client *client)
> +{
> +	struct nt36xxx_i2c *ts = i2c_get_clientdata(client);
> +
> +	free_irq(client->irq, ts);
> +	regulator_bulk_disable(NT36XXX_NUM_SUPPLIES, ts->supplies);
> +	mutex_destroy(&ts->lock);
> +	input_unregister_device(ts->input);

All of this can be removed I believe.

> +
> +	return 0;
> +}
> +
> +static int __maybe_unused nt36xxx_i2c_suspend(struct device *dev)
> +{
> +	struct nt36xxx_i2c *ts = i2c_get_clientdata(to_i2c_client(dev));
> +	u8 buf[] = { NT36XXX_EVT_HOST_CMD, NT36XXX_CMD_ENTER_SLEEP };
> +	int i, ret;
> +
> +	disable_irq(ts->client->irq);
> +
> +	ret = nt36xxx_write(ts->client, NT36XXX_BLDR_ADDR,
> +			    buf, ARRAY_SIZE(buf));
> +	if (unlikely(ret < 0)) {
> +		dev_err(&ts->client->dev, "Cannot enter suspend!!\n");
> +		return ret;
> +	}
> +
> +	/* Release all touches */
> +	for (i = 0; i < ts->max_fingers; i++) {
> +		input_mt_slot(ts->input, i);
> +		input_report_abs(ts->input, ABS_MT_TOUCH_MAJOR, 0);
> +		input_report_abs(ts->input, ABS_MT_PRESSURE, 0);
> +		input_mt_report_slot_state(ts->input, MT_TOOL_FINGER, 0);
> +	}
> +	input_sync(ts->input);

If this is needed it needs to be in input core.

> +
> +	return 0;
> +}
> +
> +static int __maybe_unused nt36xxx_i2c_resume(struct device *dev)
> +{
> +	struct nt36xxx_i2c *ts = i2c_get_clientdata(to_i2c_client(dev));
> +	int ret;
> +
> +	mutex_lock(&ts->lock);
> +
> +	if (ts->reset_gpio)
> +		gpiod_set_value(ts->reset_gpio, 1);

You are asserting reset and keep it asserted?

> +
> +	ret = nt36xxx_bootloader_reset(ts);
> +	if (ret < 0)
> +		goto end;
> +
> +	ret = nt36xxx_check_reset_state(ts, NT36XXX_STATE_REK);
> +	if (ret < 0)
> +		goto end;

Is this all needed if the device is configured for wakeup and power to
the device was not cut?

> +
> +	enable_irq(ts->client->irq);
> +end:
> +	mutex_unlock(&ts->lock);
> +	return ret;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(nt36xxx_i2c_pm,
> +			 nt36xxx_i2c_suspend, nt36xxx_i2c_resume);
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id nt36xxx_of_match[] = {
> +	{ .compatible = "novatek,nt36xxx" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, nt36xxx_of_match);
> +#endif
> +
> +static const struct i2c_device_id nt36xxx_i2c_ts_id[] = {
> +	{ "NVT-ts", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, nt36xxx_i2c_ts_id);
> +
> +static struct i2c_driver nt36xxx_i2c_ts_driver = {
> +	.driver = {
> +		.name	= "nt36xxx_ts",
> +		.of_match_table = of_match_ptr(nt36xxx_of_match),
> +		.pm	= &nt36xxx_i2c_pm,
> +	},
> +	.probe		= nt36xxx_i2c_probe,
> +	.remove		= nt36xxx_i2c_remove,
> +	.id_table	= nt36xxx_i2c_ts_id,
> +};
> +module_i2c_driver(nt36xxx_i2c_ts_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Novatek NT36XXX Touchscreen Driver");
> +
> diff --git a/drivers/input/touchscreen/nt36xxx.h b/drivers/input/touchscreen/nt36xxx.h
> new file mode 100644
> index 000000000000..6f03dfb45656
> --- /dev/null
> +++ b/drivers/input/touchscreen/nt36xxx.h
> @@ -0,0 +1,122 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2010 - 2017 Novatek, Inc.
> + * Copyright (C) 2020 AngeloGioacchino Del Regno <kholk11@gmail.com>
> + */

I'd keep all of this in .c file.

> +
> +#ifndef NT36XXX_H
> +#define NT36XXX_H
> +
> +#define NT36XXX_INPUT_DEVICE_NAME	"Novatek NT36XXX Touch Sensor"
> +
> +/* These chips have this fixed address when in bootloader :( */
> +#define NT36XXX_BLDR_ADDR 0x01
> +
> +/* Input device info */
> +#define NVT_TS_NAME "NVTCapacitiveTouchScreen"
> +
> +/* Number of bytes for chip identification */
> +#define NT36XXX_ID_LEN_MAX	6
> +
> +/* Touch info */
> +#define TOUCH_DEFAULT_MAX_WIDTH  1080
> +#define TOUCH_DEFAULT_MAX_HEIGHT 2246
> +#define TOUCH_MAX_FINGER_NUM	 10
> +#define TOUCH_MAX_PRESSURE	 1000
> +
> +/* Point data length */
> +#define POINT_DATA_LEN		65
> +
> +/* Global pages */
> +#define NT36XXX_PAGE_CHIP_INFO	0x0001f64e
> +#define NT36XXX_PAGE_CRC	0x0003f135
> +
> +/* Misc */
> +#define NT36XXX_NUM_SUPPLIES	 2
> +#define NT36XXX_MAX_RETRIES	 5
> +#define NT36XXX_MAX_FW_RST_RETRY 50
> +
> +struct nt36xxx_abs_object {
> +	u16 x;
> +	u16 y;
> +	u16 z;
> +	u8 tm;
> +};
> +
> +struct nt36xxx_fw_info {
> +	u8 fw_ver;
> +	u8 x_num;
> +	u8 y_num;
> +	u8 max_buttons;
> +	u16 abs_x_max;
> +	u16 abs_y_max;
> +	u16 nvt_pid;
> +};
> +
> +struct nt36xxx_mem_map {
> +	u32 evtbuf_addr;
> +	u32 pipe0_addr;
> +	u32 pipe1_addr;
> +	u32 flash_csum_addr;
> +	u32 flash_data_addr;
> +};
> +
> +struct nt36xxx_i2c {
> +	struct i2c_client *client;
> +	struct input_dev *input;
> +	struct regulator_bulk_data *supplies;
> +	struct gpio_desc *reset_gpio;
> +
> +	struct work_struct ts_work;
> +	struct workqueue_struct *ts_workq;
> +	struct mutex lock;
> +
> +	struct nt36xxx_fw_info fw_info;
> +	struct nt36xxx_abs_object abs_obj;
> +
> +	const struct nt36xxx_mem_map *mmap;
> +	u8 max_fingers;
> +};
> +
> +enum nt36xxx_chips {
> +	NT36525_IC = 0,
> +	NT36672A_IC,
> +	NT36676F_IC,
> +	NT36772_IC,
> +	NT36870_IC,
> +	NTMAX_IC,
> +};
> +
> +struct nt36xxx_trim_table {
> +	u8 id[NT36XXX_ID_LEN_MAX];
> +	u8 mask[NT36XXX_ID_LEN_MAX];
> +	enum nt36xxx_chips mapid;
> +};
> +
> +enum nt36xxx_cmds {
> +	NT36XXX_CMD_ENTER_SLEEP = 0x11,
> +	NT36XXX_CMD_ENTER_WKUP_GESTURE = 0x13,
> +	NT36XXX_CMD_UNLOCK = 0x35,
> +	NT36XXX_CMD_BOOTLOADER_RESET = 0x69,
> +	NT36XXX_CMD_SW_RESET = 0xa5,
> +	NT36XXX_CMD_SET_PAGE = 0xff,
> +};
> +
> +enum nt36xxx_fw_state {
> +	NT36XXX_STATE_INIT = 0xa0,	/* IC reset */
> +	NT36XXX_STATE_REK,		/* ReK baseline */
> +	NT36XXX_STATE_REK_FINISH,	/* Baseline is ready */
> +	NT36XXX_STATE_NORMAL_RUN,	/* Normal run */
> +	NT36XXX_STATE_MAX = 0xaf
> +};
> +
> +enum nt36xxx_i2c_events {
> +	NT36XXX_EVT_CHIPID = 0x4e,
> +	NT36XXX_EVT_HOST_CMD = 0x50,
> +	NT36XXX_EVT_HS_OR_SUBCMD = 0x51,   /* Handshake or subcommand byte */
> +	NT36XXX_EVT_RESET_COMPLETE = 0x60,
> +	NT36XXX_EVT_FWINFO = 0x78,
> +	NT36XXX_EVT_PROJECTID = 0x9a,
> +};
> +
> +#endif
> -- 
> 2.28.0
> 

Thanks.

-- 
Dmitry