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Date: Wed, 31 Jan 2024 11:33:53 +0100
From: Kamel Bouhara <kamel.bouhara@bootlin.com>
To: POPESCU Catalin <catalin.popescu@leica-geosystems.com>
Cc: 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-input@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	Marco Felsch <m.felsch@pengutronix.de>,
	Jeff LaBundy <jeff@labundy.com>,
	"mark.satterthwaite@touchnetix.com" <mark.satterthwaite@touchnetix.com>,
	Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
	Gregory Clement <gregory.clement@bootlin.com>,
	GEO-CHHER-bsp-development <bsp-development.geo@leica-geosystems.com>
Subject: Re: [PATCH v6 3/3] Input: Add TouchNetix axiom i2c touchscreen driver
Message-ID: <20240131103353.GC3004909@kb-xps>
References: <20240125165823.996910-1-kamel.bouhara@bootlin.com>
 <20240125165823.996910-4-kamel.bouhara@bootlin.com>
 <b466d75c-944f-4c45-80f3-993b1fe40d7a@leica-geosystems.com>
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In-Reply-To: <b466d75c-944f-4c45-80f3-993b1fe40d7a@leica-geosystems.com>

On Tue, Jan 30, 2024 at 05:32:54PM +0000, POPESCU Catalin wrote:
> Hi Kamel,
>

Hi,

> I have a few remarks regarding the population of the usage table
> function, see inline.
>
> On 25.01.24 17:58, Kamel Bouhara wrote:
> > [Some people who received this message don't often get email from kamel.bouhara@bootlin.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
> >
> > This email is not from Hexagon’s Office 365 instance. Please be careful while clicking links, opening attachments, or replying to this email.
> >
> >
> > 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                                  |   1 +
> >   drivers/input/touchscreen/Kconfig            |  12 +
> >   drivers/input/touchscreen/Makefile           |   1 +
> >   drivers/input/touchscreen/touchnetix_axiom.c | 664 +++++++++++++++++++
> >   4 files changed, 678 insertions(+)
> >   create mode 100644 drivers/input/touchscreen/touchnetix_axiom.c
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 4752d8436dbb..337ddac6c74b 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -21436,6 +21436,7 @@ M:      Kamel Bouhara <kamel.bouhara@bootlin.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
> >
> >   THUNDERBOLT DMA TRAFFIC TEST DRIVER
> >   M:     Isaac Hazan <isaac.hazan@intel.com>
> > diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> > index e3e2324547b9..f36bee8d8696 100644
> > --- a/drivers/input/touchscreen/Kconfig
> > +++ b/drivers/input/touchscreen/Kconfig
> > @@ -803,6 +803,18 @@ 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
> > +       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 62bd24f3ac8e..8e32a2df5e18 100644
> > --- a/drivers/input/touchscreen/Makefile
> > +++ b/drivers/input/touchscreen/Makefile
> > @@ -88,6 +88,7 @@ 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..cbb5525b83f5
> > --- /dev/null
> > +++ b/drivers/input/touchscreen/touchnetix_axiom.c
> > @@ -0,0 +1,664 @@
> > +// 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
> > +/*
> > + * 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 regulator *vdda;
> > +       struct regulator *vddi;
> > +       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;
> > +       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);
> > +
> > +       __le32 preamble = get_unaligned_le32((u8 *)&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;
> please force initialization of max_report_len to 0.

Fixed, thanks !

> > +       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 = 1; usage_id < AXIOM_U31_MAX_USAGES; usage_id++) {
>
> usage_id should start at 0, since it's used to compute the offset in the
> page 1 of u31.
> if you start with usage_id=1, then whatever is the 1st usage of the
> usage table gets jumped out...

You're right, first usage id is u01, I think that's what induced my
mistake here.

> also, you should stop the loop at num_usages, otherwise you're going to
> read garbage after the end of rx_data buffer...
> this garbage would end up in wrong computation of max_report_len then in
> failure of reading any touch report.
>

Reading num_usages is indeed a more clever choice here, thanks again !

> > +               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;
> > +
> > +               if (!num_pages)
> > +                       usage_table[id].is_report = true;
> please add an else statement to set is_report to false.

Fixed in v7, thanks.

> > +
> > +               /* 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 slot;
> > +
> > +       /* 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;
> > +
> > +       slot = target->index;
> > +
> > +       dev_dbg(ts->dev, "U41 Target T%u, slot:%u present:%u, x:%u, y:%u, z:%d\n",
> > +               target->index, slot, 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;
> > +               input_mt_slot(input_dev, slot);
> > +
> > +               if (!slot)
> > +                       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_mt_slot(input_dev, slot);
> > +               input_report_abs(input_dev, ABS_MT_TRACKING_ID, slot);
> > +               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 (!slot)
> > +                       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;
> > +               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]);
> > +               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];
> > +
> > +               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;
> > +       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 */
> > +       u8 *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(110);
> > +}
> > +
> > +static int axiom_i2c_probe(struct i2c_client *client)
> > +{
> > +       u32 poll_interval = POLL_INTERVAL_DEFAULT_MS;
> > +       struct device *dev = &client->dev;
> > +       struct input_dev *input_dev;
> > +       struct axiom_data *ts;
> > +       u32 startup_delay_ms;
> > +       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;
> > +       }
> > +
> > +       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);
> > +
> > +       ts->vddi = devm_regulator_get_optional(dev, "vddi");
> > +       if (!IS_ERR(ts->vddi)) {
> > +               error = devm_regulator_get_enable(dev, "vddi");
> > +               if (error)
> > +                       return dev_err_probe(&client->dev, error,
> > +                                            "Failed to enable vddi regulator\n");
> > +       }
> > +
> > +       ts->vdda = devm_regulator_get_optional(dev, "vdda");
> > +       if (!IS_ERR(ts->vdda)) {
> > +               error = devm_regulator_get_enable(dev, "vdda");
> > +               if (error)
> > +                       return dev_err_probe(&client->dev, error,
> > +                                            "Failed to enable vdda regulator\n");
> > +               if (!device_property_read_u32(dev, "startup-time-ms", &startup_delay_ms))
> > +                       msleep(startup_delay_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 = input_register_device(input_dev);
> > +       if (error)
> > +               return dev_err_probe(ts->dev, error,
> > +                                    "Could not register with Input Sub-system.\n");
> > +
> > +       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);
> > +       }
> > +
> > +       return 0;
> > +}
> > +
> > +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
> >
>

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