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Date: Wed, 5 Jun 2024 14:47:46 +0200
From: Kamel Bouhara <kamel.bouhara@bootlin.com>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: 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>,
	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
Subject: Re: [PATCH v13 3/3] Input: Add TouchNetix axiom i2c touchscreen
 driver
Message-ID: <20240605124746.GA57733@tpx1.home>
References: <20240603153929.29218-1-kamel.bouhara@bootlin.com>
 <20240603153929.29218-4-kamel.bouhara@bootlin.com>
 <Zl5ZmYyntq7OJOvZ@google.com>
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In-Reply-To: <Zl5ZmYyntq7OJOvZ@google.com>

Le Mon, Jun 03, 2024 at 05:02:33PM -0700, Dmitry Torokhov a ?crit :
> Hi Kamel,
>

Hi Dmitry,

> On Mon, Jun 03, 2024 at 05:39:25PM +0200, Kamel Bouhara wrote:
> > 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;
>
> This is probably a 'bool'.

Fixed thanks.

>
> > +	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;
>
> What does "insert" mean here?

I think this means target data are reported.

>
> > +	bool touch;
> > +};
> > +
> > +struct axiom_target_report {
> > +	u8 index;
> > +	u8 present;
>
> bool?
>
> > +	u16 x;
> > +	u16 y;
> > +	s8 z;
> > +};
> > +
> > +struct axiom_cmd_header {
> > +	__le16 target_address;
> > +	__le16 length;
> > +} __packed;
>
> You do not need to declare this as packed, it is naturally aligned. You
> can also make it a union with __le32 to ensure overall alignment.

Ack, fixed for v14.

>
> > +
> > +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);
>
> What exactly are we waiting for after getting the data?

That is the minimum delay required the device need to flush it's
internal dma buffers.

>
> > +
> > +	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;
>
> Why is this needed? Input/MT core already tries to suppress duplicate
> events, I do not think we need to do it here.
>

This indeed make sure we don't have twice the same report processed.

> > +
> > +	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);
>
> You only need to emit ABS_MT_DISTANCE and ABS_MT_PRESSURE. The
> single-touch variants should be generated by the input core as part of
> sending out the frame.
>

Ack, thanks.

> > +		} 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));
>
> Why do you emit BTN_TOUCH manually instead of replying on
> input_mt_sync_frame() calling input_mt_pointer_emulation().

Sorry this really requires a comment line as it is to indicate when the
target is the first reported contact and Im actually not sure this
should be kept as it.

>
> > +		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);
>
> I find it confusing that you send out coordinates here, and the rest of
> events in axiom_process_u41_report_target()... Can it all be done in one
> place?

Sure this will be moved in axiom_process_u41_report_target() for v14.

>
> > +		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);
>
> This does not really belong to the input subsystem. I recommend using
> debugfs to provide this data. Some drivers also use v4l to provide a
> "picture" of the heat map.

Ack, I will just remove it here, this is used when force sensing data
(u46) are available.

>
> > +	}
> > +}
> > +
> > +/*
> > + * 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);
>
> Should this be called unconditionally (and matching msleep() be removed
> from axiom_i2c_probe)?
>

The reset gpio being optional we need to make sure the time after a
power ON sequence is meet. I could still move the power sequence in a
axiom_power_on() if this make things clearer.

> > +
> > +	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);
>
> The only tool you report is finger, who do you declare more?

This is a mistake only finger is required.

>
> > +	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);
>
> The driver does not emit any relative events...

Fixed, thanks.

>
> > +	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");
>
> I do not think you should fall back to polling mode if you fail to get
> interrupt. If it was not specified (client->irq) then I can see that we
> might want to fall back, but if the system configured for using
> interrupt and you can not get it you should bail out.
>

Yes, clear, the polling mode can be decorrelated to the irq not provided
case.

> > +
> > +		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);
>
> Please use
>
> 	error = input_register_device(..);
> 	if (error)
> 		return dev_err_probe(...);
>
> 	return 0;
>

Fixed, thanks.

> Thanks.
>
> --
> Dmitry

--
Kamel Bouhara, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com