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Message-ID: <d760ad5e60b21816a395713f004ca14c@bootlin.com>
Date: Mon, 13 Nov 2023 14:32:12 +0100
From: kamel.bouhara@...tlin.com
To: Jeff LaBundy <jeff@...undy.com>
Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>,
Henrik Rydberg <rydberg@...math.org>,
linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
devicetree@...r.kernel.org, Marco Felsch <m.felsch@...gutronix.de>,
mark.satterthwaite@...chnetix.com, bartp@...sheep.co.uk,
hannah.rossiter@...chnetix.com,
Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
Gregory Clement <gregory.clement@...tlin.com>,
bsp-development.geo@...ca-geosystems.com
Subject: Re: [PATCH v3 3/3] Input: Add TouchNetix axiom i2c touchscreen driver
Le 2023-10-22 23:54, Jeff LaBundy a écrit :
> Hi Kamel,
Hi Jeff,
>
> On Thu, Oct 12, 2023 at 09:40:34AM +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@...tlin.com>
>> ---
>> MAINTAINERS | 1 +
>> drivers/input/touchscreen/Kconfig | 13 +
>> drivers/input/touchscreen/Makefile | 1 +
>> .../input/touchscreen/touchnetix_axiom_i2c.c | 740
>> ++++++++++++++++++
>> 4 files changed, 755 insertions(+)
>> create mode 100644 drivers/input/touchscreen/touchnetix_axiom_i2c.c
>
> Please do not include 'i2c' in the filename. If the driver is expanded
> in
> the future to support SPI, it would make sense to have
> touchnetix_axiom.c,
> touchnetix_axiom_i2c.c and touchnetix_axiom_spi.c. To prevent this
> driver
> from having to be renamed in that case, just call it
> touchnetix_axiom.c.
>
Sure but the generic part of the code could also be moved to
touchnetix_axiom.c.
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 12ae8bc6b8cf..2d1e0b025e89 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -21415,6 +21415,7 @@ M: Kamel Bouhara <kamel.bouhara@...tlin.com>
>> L: linux-input@...r.kernel.org
>> S: Maintained
>>
>> F: Documentation/devicetree/bindings/input/touchscreen/touchnetix,axiom-ax54a.yaml
>> +F: drivers/input/touchscreen/touchnetix_axiom_i2c.c
>>
>> THUNDERBOLT DMA TRAFFIC TEST DRIVER
>> M: Isaac Hazan <isaac.hazan@...el.com>
>> diff --git a/drivers/input/touchscreen/Kconfig
>> b/drivers/input/touchscreen/Kconfig
>> index e3e2324547b9..58665ccbe077 100644
>> --- a/drivers/input/touchscreen/Kconfig
>> +++ b/drivers/input/touchscreen/Kconfig
>> @@ -803,6 +803,19 @@ config TOUCHSCREEN_MIGOR
>> To compile this driver as a module, choose M here: the
>> module will be called migor_ts.
>>
>> +config TOUCHSCREEN_TOUCHNETIX_AXIOM_I2C
>> + tristate "TouchNetix AXIOM based touchscreen controllers"
>> + depends on I2C
>> + depends on GPIOLIB || COMPILE_TEST
>
> All gpiod_*() functions used in this driver have a dummy function for
> the
> CONFIG_GPIOLIB=n case, so this dependency is unnecessary.
>
Yes, thanks.
>> + 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_i2c.
>> +
>> config TOUCHSCREEN_TOUCHRIGHT
>> tristate "Touchright serial touchscreen"
>> select SERIO
>> diff --git a/drivers/input/touchscreen/Makefile
>> b/drivers/input/touchscreen/Makefile
>> index 62bd24f3ac8e..23b6fb8864b0 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-$(CONFIG_TOUCHSCREEN_TOUCHNETIX_AXIOM_I2C) +=
>> touchnetix_axiom_i2c.o
>> obj-$(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_i2c.c
>> b/drivers/input/touchscreen/touchnetix_axiom_i2c.c
>> new file mode 100644
>> index 000000000000..fb6239a87341
>> --- /dev/null
>> +++ b/drivers/input/touchscreen/touchnetix_axiom_i2c.c
>> @@ -0,0 +1,740 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * TouchNetix aXiom Touchscreen Driver
>> + *
>> + * Copyright (C) 2020-2023 TouchNetix Ltd.
>> + *
>> + * Author(s): Bart Prescott <bartp@...sheep.co.uk>
>> + * Pedro Torruella <pedro.torruella@...chnetix.com>
>> + * Mark Satterthwaite <mark.satterthwaite@...chnetix.com>
>> + * Hannah Rossiter <hannah.rossiter@...chnetix.com>
>> + * Kamel Bouhara <kamel.bouhara@...tlin.com>
>> + *
>> + */
>> +
>> +#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/interrupt.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>
> Please #include mod_devicetable.h as well.
>
OK is this only for the sake of clarity ? As mod_devicetable.h is
already included in linux/of.h ?
>> +#include <linux/of.h>
>> +#include <linux/pm.h>
>
> In addition to Marco's comment about unused includes, pm.h does not
> appear
> to be used either.
>
Ack, thx.
>> +#include <linux/slab.h>
>> +#include <linux/string.h>
>> +
>> +/*
>> + * Runtime TCP mode: device is executing normal code and is
>> + * accessible via the Touch Controller Mode
>> + */
>> +#define BOOT_TCP 0
>> +/*
>> + * Bootloader BLP mode: device is executing bootloader and is
>> + * accessible via the Boot Loader Protocol.
>> + */
>> +#define BOOT_BLP 1
>> +#define AXIOM_PROX_LEVEL -128
>> +/*
>> + * Register group u31 has 2 pages for usage table entries.
>> + * (2 * AXIOM_COMMS_PAGE_SIZE) / AXIOM_U31_BYTES_PER_USAGE = 85
>> + */
>> +#define AXIOM_U31_MAX_USAGES 85
>> +#define AXIOM_U31_BYTES_PER_USAGE 6
>> +#define AXIOM_U31_PAGE0_LENGTH 0x0C
>> +#define AXIOM_U31_BOOTMODE_MASK BIT(7)
>> +#define AXIOM_U31_FW_INFO_VARIANT_MASK GENMASK(6, 0)
>> +#define AXIOM_U31_FW_INFO_STATUS_MASK BIT(7)
>> +
>> +#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_OVERFLOW_MASK BIT(7)
>> +#define AXIOM_COMMS_REPORT_LEN_MASK GENMASK(7, 0)
>> +
>> +#define AXIOM_REBASELINE_CMD 0x03
>> +
>> +#define AXIOM_REPORT_USAGE_ID 0x34
>> +#define AXIOM_DEVINFO_USAGE_ID 0x31
>> +#define AXIOM_USAGE_2HB_REPORT_ID 0x01
>> +#define AXIOM_REBASELINE_USAGE_ID 0x02
>> +#define AXIOM_USAGE_2AUX_REPORT_ID 0x46
>> +#define AXIOM_USAGE_2DCTS_REPORT_ID 0x41
>> +
>> +#define AXIOM_PAGE_MASK GENMASK(15, 8)
>> +#define AXIOM_PAGE_OFFSET_MASK GENMASK(7, 0)
>> +
>> +struct axiom_devinfo {
>> + char bootloader_fw_major;
>
> Please use standard kernel type definitions, specifically u8 in place
> of char.
>
Ack.
>> + char bootloader_fw_minor;
>> + char bootmode;
>> + u16 device_id;
>> + char fw_major;
>> + char fw_minor;
>> + char fw_info_extra;
>> + char tcp_revision;
>> + u16 jedec_id;
>> + char num_usages;
>> + char silicon_revision;
>> +};
>> +
>> +/*
>> + * Describes parameters of a specific usage, essenstially a single
>> element of
>> + * the "Usage Table"
>> + */
>> +struct usage_entry {
>> + char id;
>> + char is_report;
>> + char start_page;
>> + char num_pages;
>> +};
>> +
>> +/*
>> + * Holds state of a touch or target when detected prior a touch (eg.
>> + * hover or proximity events).
>> + */
>
> Nit: this comment is misleading. The enum itself does not hold state;
> it
> represents state. A variable defined using this enum holds the state.
>
Ok.
>> +enum axiom_target_state {
>> + TARGET_STATE_NOT_PRESENT = 0,
>> + TARGET_STATE_PROX = 1,
>> + TARGET_STATE_HOVER = 2,
>> + TARGET_STATE_TOUCHING = 3,
>> + TARGET_STATE_MIN = TARGET_STATE_NOT_PRESENT,
>> + TARGET_STATE_MAX = TARGET_STATE_TOUCHING,
>> +};
>
> Please namespace these, i.e. AXIOM_TARGET_STATE_*.
>
>> +
>> +struct u41_target {
>> + enum axiom_target_state state;
>> + u16 x;
>> + u16 y;
>> + s8 z;
>> + bool insert;
>> + bool touch;
>> +};
>
> Please namespace this struct definition as you have done below.
>
Sure.
>> +
>> +struct axiom_target_report {
>> + u8 index;
>> + u8 present;
>> + u16 x;
>> + u16 y;
>> + s8 z;
>> +};
>> +
>> +struct axiom_cmd_header {
>> + u16 target_address;
>> + u16 length:15;
>> + u16 read:1;
>> +} __packed;
>> +
>> +struct axiom_data {
>> + struct axiom_devinfo devinfo;
>> + struct device *dev;
>> + struct gpio_desc *reset_gpio;
>> + struct gpio_desc *irq_gpio;
>> + struct i2c_client *client;
>> + struct input_dev *input_dev;
>> + u32 max_report_len;
>> + u32 report_overflow_counter;
>> + u32 report_counter;
>> + char rx_buf[AXIOM_COMMS_MAX_USAGE_PAGES * AXIOM_COMMS_PAGE_SIZE];
>> + struct u41_target targets[AXIOM_U41_MAX_TARGETS];
>> + struct usage_entry usage_table[AXIOM_U31_MAX_USAGES];
>> + bool usage_table_populated;
>> +};
>> +
>> +/*
>> + * aXiom devices are typically configured to report
>> + * touches at a rate of 100Hz (10ms). For systems
>> + * that require polling for reports, 100ms seems like
>> + * an acceptable polling rate.
>> + * 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 100
>
> I'd rather we take this information from device tree; it seems
> 'poll-interval'
> is a common property used by other drivers.
>
>> +
>> +/* Translate usage/page/offset triplet into physical address. */
>> +static u16
>> +usage_to_target_address(struct axiom_data *ts, char usage, char page,
>> + char offset)
>
> The line break after the function type is a bit confusing; please use
> this
> more common style and namespace all functions:
>
> static u16 axiom_usage_to_target_address(...,
> ...);
>
> Note any line breaks are aligned to the opening parenthesis.
>
Fixed, thx.
>> +{
>> + struct axiom_devinfo *device_info;
>> + struct usage_entry *usage_table;
>> + u32 i;
>> +
>> + device_info = &ts->devinfo;
>> + usage_table = ts->usage_table;
>> +
>> + /* 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;
>> + }
>> +
>> + for (i = 0; i < device_info->num_usages; i++) {
>> + if (usage_table[i].id != usage)
>> + continue;
>> +
>> + if (page >= usage_table[i].num_pages) {
>> + dev_err(ts->dev, "Invalid usage table! usage: %u, page: %u,
>> offset: %u\n",
>> + usage, page, offset);
>> + return 0xffff;
>> + }
>> + }
>> +
>> + return ((usage_table[i].start_page + page) << 8) + offset;
>> +}
>> +
>> +static int
>> +axiom_i2c_read(struct i2c_client *client, u8 usage, u8 page, u8 *buf,
>> u16 len)
>> +{
>> + struct axiom_data *ts = i2c_get_clientdata(client);
>> + struct axiom_cmd_header cmd_header;
>> + struct i2c_msg msg[2];
>> + int ret;
>> +
>> + cmd_header.target_address = cpu_to_le16(usage_to_target_address(ts,
>> usage, page, 0));
>> + cmd_header.length = cpu_to_le16(len);
>> + cmd_header.read = 1;
>> +
>> + msg[0].addr = client->addr;
>> + msg[0].flags = 0;
>> + msg[0].len = sizeof(cmd_header);
>> + msg[0].buf = (u8 *)&cmd_header;
>> +
>> + msg[1].addr = client->addr;
>> + msg[1].flags = I2C_M_RD;
>> + msg[1].len = len;
>> + msg[1].buf = (char *)buf;
>
> Again, please use u8 in place of char, as was done for the first
> element.
OK.
>
>> +
>> + ret = i2c_transfer(client->adapter, msg, 2);
>
> Please use ARRAY_SIZE(msg) above as you do below.
>
>> + if (ret != ARRAY_SIZE(msg)) {
>> + dev_err(&client->dev,
>> + "Failed reading usage %#x page %#x, error=%d\n",
>> + usage, page, ret);
>> + return -EIO;
>> + }
>
> This check papers over negative error codes that may have been returned
> by
> i2c_transfer(). For ret < 0 you should return ret, and only return -EIO
> for
> 0 <= ret < ARRAY_SIZE(msg).
>
> More importantly, however, if this device supports multiple transports
> and
> you expect SPI support can be added in the future, you really should
> use
> regmap throughout in order to avoid ripping up this driver later.
>
I have a doubt on wether or not regmap can be used for SPI as there is
some
specific padding required for SPI.
>> +
>> + return 0;
>> +}
>> +
>> +static int
>> +axiom_i2c_write(struct i2c_client *client, u8 usage, u8 page, u8
>> *buf, u16 len)
>> +{
>> + struct axiom_data *ts = i2c_get_clientdata(client);
>> + struct axiom_cmd_header cmd_header;
>> + struct i2c_msg msg[2];
>> + int ret;
>> +
>> + cmd_header.target_address = cpu_to_le16(usage_to_target_address(ts,
>> usage, page, 0));
>> + cmd_header.length = cpu_to_le16(len);
>> + cmd_header.read = 0;
>> +
>> + msg[0].addr = client->addr;
>> + msg[0].flags = 0;
>> + msg[0].len = sizeof(cmd_header);
>> + msg[0].buf = (u8 *)&cmd_header;
>> +
>> + msg[1].addr = client->addr;
>> + msg[1].flags = 0;
>> + msg[1].len = len;
>> + msg[1].buf = (char *)buf;
>> +
>> + ret = i2c_transfer(client->adapter, msg, 2);
>> + if (ret < 0) {
>> + dev_err(&client->dev,
>> + "Failed to write usage %#x page %#x, error=%d\n", usage,
>> + page, ret);
>> + return ret;
>> + }
>
> The error handling between your read and write wrappers is
> inconsistent;
> please see my comment above.
>
> Is there any reason i2c_master_send() cannot work here? I'm guessing
> the
> controller needs a repeated start in between the two messages?
>
Yes reads requires repeated starts between each messages.
For writes I could still use i2c_master_send() but what makes it more
relevant here ?
> For these kind of special requirements, it's helpful to add some
> comments
> as to why the HW calls for additional housekeeping.
>
OK.
>> +
>> + return 0;
>> +}
>> +
>> +/*
>> + * Decodes and populates the local Usage Table.
>> + * Given a buffer of data read from page 1 onwards of u31 from an
>> aXiom
>> + * device.
>> + */
>
> What is a usage table? These comments aren't helpful unless some of the
> underlying concepts are defined as well.
It's a set of registers regrouped in categories (data, configuration,
device and report).
I'll try to clarify it.
>
>> +static u32 axiom_populate_usage_table(struct axiom_data *ts, char
>> *rx_data)
>> +{
>> + u32 usage_id = 0;
>
> There is no need to initialize this iterator.
>
>> + u32 max_report_len = 0;
>> + struct axiom_devinfo *device_info;
>> + struct usage_entry *usage_table;
>> +
>> + device_info = &ts->devinfo;
>> + usage_table = ts->usage_table;
>> +
>> + for (usage_id = 0; usage_id < device_info->num_usages; usage_id++) {
>> + u16 offset = (usage_id * AXIOM_U31_BYTES_PER_USAGE);
>> + char id = rx_data[offset + 0];
>> + char start_page = rx_data[offset + 1];
>> + char num_pages = rx_data[offset + 2];
>
> Please consider whether you can use a packed struct for this decoding.
>
>> + u32 max_offset = ((rx_data[offset + 3] & AXIOM_PAGE_OFFSET_MASK) +
>> 1) * 2;
>> +
>> + if (!num_pages)
>> + usage_table[usage_id].is_report = true;
>> +
>> + /* Store the entry into the usage table */
>> + usage_table[usage_id].id = id;
>> + usage_table[usage_id].start_page = start_page;
>> + usage_table[usage_id].num_pages = num_pages;
>> +
>> + dev_dbg(ts->dev, "Usage %2u Info: %*ph\n", usage_id,
>> + AXIOM_U31_BYTES_PER_USAGE,
>> + &rx_data[offset]);
>
> Nit: this line break seems unnecessary.
>
>> +
>> + /* Identify the max report length the module will receive */
>> + if (usage_table[usage_id].is_report && max_offset > max_report_len)
>> + max_report_len = max_offset;
>> + }
>> + ts->usage_table_populated = true;
>> +
>> + return max_report_len;
>> +}
>> +
>> +/* Retrieve, store and print the axiom device information */
>
> This comment does not seem particularly helpful.
>
>> +static int axiom_discover(struct axiom_data *ts)
>> +{
>> + struct axiom_devinfo *devinfo = &ts->devinfo;
>> + struct device *dev = ts->dev;
>> + char *rx_data = ts->rx_buf;
>> + int ret;
>
> In input, variables that represent a negative error code (fail) or zero
> (pass)
> tend to be called 'error'.
>
>> +
>> + /*
>> + * Fetch the first page of usage u31 to get the
>> + * device information and the number of usages
>> + */
>> + ret = axiom_i2c_read(ts->client, AXIOM_DEVINFO_USAGE_ID, 0, rx_data,
>> + AXIOM_U31_PAGE0_LENGTH);
>> + if (ret)
>> + return ret;
>> +
>> + devinfo->bootmode = (rx_data[0] & AXIOM_U31_BOOTMODE_MASK);
>> + devinfo->device_id = ((rx_data[1] & AXIOM_PAGE_OFFSET_MASK) << 8) |
>> rx_data[0];
>> + devinfo->fw_minor = rx_data[2];
>> + devinfo->fw_major = rx_data[3];
>> + devinfo->fw_info_extra = rx_data[4];
>> + devinfo->bootloader_fw_minor = rx_data[6];
>> + devinfo->bootloader_fw_major = rx_data[7];
>> + devinfo->jedec_id = (rx_data[8]) | (rx_data[9] << 8);
>> + devinfo->num_usages = rx_data[10];
>> + devinfo->silicon_revision = rx_data[11];
>
> Opinions may vary here, but mine is that it is a waste of memory and
> time
> to read and parse all of this data, only to print it at debug level.
> Unless
> these variables are used elsewhere or reported to user space via sysfs,
> I
> would drop all of this. It seems like cruft leftover from a vendor
> driver.
>
> If you feel strongly about keeping these variables, then axiom_devinfo
> should
> be defined as a packed struct to prevent having to disect rx_data[]
> byte by
> byte. You should just read into &devinfo directly.
Ack thx.
>
>> +
>> + dev_dbg(dev, " Boot Mode: %s\n", ts->devinfo.bootmode ? "BLP" :
>> "TCP");
>> + dev_dbg(dev, " Device ID : %04x\n", ts->devinfo.device_id);
>> + dev_dbg(dev, " Firmware Rev : %02x.%02x\n", ts->devinfo.fw_major,
>> + ts->devinfo.fw_minor);
>> + dev_dbg(dev, " Bootloader Rev : %02x.%02x\n",
>> + ts->devinfo.bootloader_fw_major,
>> + ts->devinfo.bootloader_fw_minor);
>> + dev_dbg(dev, " FW Extra Info : %04x\n",
>> ts->devinfo.fw_info_extra);
>> + dev_dbg(dev, " Silicon : %02x\n", ts->devinfo.jedec_id);
>> + dev_dbg(dev, " Num Usages : %04x\n", ts->devinfo.num_usages);
>> +
>> + /* Read the second page of usage u31 to get the usage table */
>> + ret = axiom_i2c_read(ts->client, AXIOM_DEVINFO_USAGE_ID, 1, rx_data,
>> + (AXIOM_U31_BYTES_PER_USAGE * ts->devinfo.num_usages));
>> + if (ret)
>> + return ret;
>> +
>> + ts->max_report_len = axiom_populate_usage_table(ts, rx_data);
>> + dev_dbg(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;
>> + enum axiom_target_state current_state;
>> + struct u41_target *target_prev_state;
>> + struct device *dev = ts->dev;
>> + bool update = false;
>> + int slot;
>> +
>> + /* Verify the target index */
>> + if (target->index >= AXIOM_U41_MAX_TARGETS) {
>> + dev_dbg(dev, "Invalid target index! %u\n", target->index);
>> + return false;
>> + }
>> +
>> + target_prev_state = &ts->targets[target->index];
>> +
>> + current_state = TARGET_STATE_NOT_PRESENT;
>> +
>> + if (target->present) {
>> + if (target->z >= 0)
>> + current_state = TARGET_STATE_TOUCHING;
>> + else if (target->z > AXIOM_PROX_LEVEL && target->z < 0)
>> + current_state = TARGET_STATE_HOVER;
>> + else if (target->z AXIOM_PROX_LEVEL)
>> + current_state = 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(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 TARGET_STATE_NOT_PRESENT:
>> + case TARGET_STATE_PROX:
>> + if (target_prev_state->insert)
>> + break;
>> + update = true;
>> + target_prev_state->insert = false;
>> + input_mt_slot(input_dev, slot);
>> +
>> + if (!slot)
>> + input_report_key(input_dev, BTN_LEFT, 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 TARGET_STATE_HOVER:
>> + case TARGET_STATE_TOUCHING:
>> + target_prev_state->insert = true;
>> + update = 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_X, target->x);
>> + input_report_abs(input_dev, ABS_MT_POSITION_Y, target->y);
>> + input_report_abs(input_dev, ABS_Y, target->y);
>> +
>> + if (current_state == 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_LEFT, (current_state ==
>> + TARGET_STATE_TOUCHING));
>> + 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;
>> +
>> + if (update)
>> + input_mt_sync_frame(input_dev);
>> +
>> + return update;
>> +}
>> +
>> +/*
>> + * Take a raw buffer with u41 report data and decode it.
>> + * Also generate input events if needed.
>> + * rx_buf: ptr to a byte array [0]: Usage number [1]: Status LSB [2]:
>> Status MSB
>> + */
>> +static void axiom_process_u41_report(struct axiom_data *ts, char
>> *rx_buf)
>> +{
>> + struct input_dev *input_dev = ts->input_dev;
>> + struct axiom_target_report target;
>> + bool update_done = false;
>> + u16 target_status;
>> + u32 i;
>> +
>> + target_status = ((rx_buf[1]) | (rx_buf[2] << 8));
>> +
>> + for (i = 0; i < AXIOM_U41_MAX_TARGETS; i++) {
>> + char target_step = rx_buf[(i * 4)];
>> +
>> + target.index = i;
>> + target.present = ((target_status & (1 << i)) != 0) ? 1 : 0;
>> + target.x = ((target_step + 3) | ((target_step + 4) << 8));
>> + target.y = ((target_step + 5) | ((target_step + 6) << 8));
>> + target.z = (s8)(rx_buf[i + 43]);
>> + update_done |= axiom_process_u41_report_target(ts, &target);
>> + }
>> +
>> + if (update_done)
>> + input_sync(input_dev);
>> +}
>> +
>> +static void axiom_process_u46_report(struct axiom_data *ts, char
>> *rx_buf)
>> +{
>> + struct input_dev *input_dev = ts->input_dev;
>> + u32 event_value;
>> + u16 aux_value;
>> + u32 i = 0;
>> +
>> + for (i = 0; i < AXIOM_U46_AUX_CHANNELS; i++) {
>> + char target_step = rx_buf[(i * 2)];
>> +
>> + aux_value = (((target_step + 2) << 8) | (target_step + 1)) &
>> AXIOM_U46_AUX_MASK;
>> + event_value = (i << 16) | (aux_value);
>> + input_event(input_dev, EV_MSC, MSC_RAW, event_value);
>> + }
>> +
>> + input_mt_sync(input_dev);
>> + input_sync(input_dev);
>> +}
>
> Please forgive me in case I am simply slow to understand, but I really
> do
> not think we can accept this kind of encapsulation. We have multiple
> calls
> to input_mt_sync() and input_sync() spread across different functions,
> one
> of which uses a 'done' flag to make a decision. It's also unclear what
> 'u41'
> and 'u46' represent. The current implementation is too confusing to
> review
> effectively IMO.
>
> What we ultimately want to see here is one homogenous event handler
> where
> MT slots are processed, followed by one call to input_mt_sync(), itself
> followed by one call to input_sync() after any additional events (e.g.
> keys)
> are processed. It's certainly OK to break out some processing into
> helper
> functions, but we ultimately want to see one entry point into the input
> core.
>
> Please consider whether there is a more maintainable way to organize
> this
> processing; it seems more complex than other touchscreen drivers.
OK I'll rework this in v4.
>
>> +
>> +/*
>> + * Validates the crc and demultiplexes the axiom reports to the
>> appropriate
>> + * report handler
>> + */
>> +static void axiom_handle_events(struct axiom_data *ts)
>> +{
>> + char *report_data = ts->rx_buf;
>> + struct device *dev = ts->dev;
>> + char usage = report_data[1];
>> + u16 crc_report;
>> + u16 crc_calc;
>> + char len;
>> +
>> + axiom_i2c_read(ts->client, AXIOM_REPORT_USAGE_ID, 0, report_data,
>> ts->max_report_len);
>
> If this read fails due to a HW problem, the rest of this function will
> act
> upon garbage data.
>
>> +
>> + if ((report_data[0] & AXIOM_COMMS_OVERFLOW_MASK) != 0)
>> + ts->report_overflow_counter++;
>> +
>> + len = (report_data[0] & AXIOM_COMMS_REPORT_LEN_MASK) * 2;
>> + if (!len) {
>> + dev_err(dev, "Zero length report discarded.\n");
>> + return;
>
> Please make the return type of helper functions like
> axiom_handle_events() of
> type int, and consider -ENODATA for this particular condition.
>
> Even though callers to axiom_handle_events() are void at this time, you
> should
> start out with the driver being flexible in case it grows over time.
>
>> + }
>> +
>> + dev_dbg(dev, "Payload Data %*ph\n", len, report_data);
>> +
>> + /* Validate the report CRC */
>> + crc_report = (report_data[len - 1] << 8) | (report_data[len - 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;
>
> Return -EINVAL after promoting the return type to int.
OK.
>
>> + }
>> +
>> + switch (usage) {
>> + case AXIOM_USAGE_2DCTS_REPORT_ID:
>> + axiom_process_u41_report(ts, &report_data[1]);
>> + break;
>> +
>> + case AXIOM_USAGE_2AUX_REPORT_ID:
>> + /* This is an aux report (force) */
>> + axiom_process_u46_report(ts, &report_data[1]);
>> + break;
>> +
>> + case AXIOM_USAGE_2HB_REPORT_ID:
>> + /* This is a heartbeat report */
>> + break;
>
> Since 'usage' is read from the HW, we need a default branch for
> handling
> unexpected values.
Ack thx.
>
>> + }
>> +
>> + ts->report_counter++;
>
> This counter appears to be unused.
>
Fixed thx.
>> +}
>> +
>> +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(100);
>> +}
>> +
>> +/* Rebaseline the touchscreen, effectively zero-ing it */
>
> What does it mean to rebaseline the touchscreen? I'm guessing it means
> to null out or normalize pressure? Please consider a less
> colloquialized
> function name.
>
> Out of curiousity, what happens if the user's hand happens to be on the
> touch surface at the time you call axiom_rebaseline()? Does the device
> recover on its own?
This indeed force the controller to measure a new capacitance by zeoring
it,
I don't really know if it's harmful, yet the documentation says
rebaseline is
for tuning or debug purpose.
I believe this is done for testing the communication.
>
>> +static int axiom_rebaseline(struct axiom_data *ts)
>> +{
>> + char buffer[8] = {};
>
> Are you expecting each element to be initialized to zero?
Yes.
>
>> +
>> + buffer[0] = AXIOM_REBASELINE_CMD;
>> +
>> + return axiom_i2c_write(ts->client, AXIOM_REPORT_USAGE_ID, 0, buffer,
>> sizeof(buffer));
>> +}
>> +
>> +static int axiom_i2c_probe(struct i2c_client *client)
>> +{
>> + struct device *dev = &client->dev;
>> + struct input_dev *input_dev;
>> + struct axiom_data *ts;
>> + int ret;
>> + int target;
>> +
>> + ts = devm_kzalloc(dev, sizeof(*ts), GFP_KERNEL);
>> + if (!ts)
>> + return -ENOMEM;
>> +
>> + ts->client = client;
>> + i2c_set_clientdata(client, ts);
>> + ts->dev = dev;
>> +
>> + ts->irq_gpio = devm_gpiod_get_optional(dev, "irq", GPIOD_IN);
>> + if (IS_ERR(ts->irq_gpio))
>> + return dev_err_probe(dev, PTR_ERR(ts->irq_gpio), "failed to get irq
>> GPIO");
>> +
>> + 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");
>> +
>> + axiom_reset(ts->reset_gpio);
>
> We shouldn't call axiom_reset() if reset_gpio is NULL. Even though the
> calls to gpiod_set_value_cansleep() will bail safely, there is no
> reason
> to make the CPU sleep for 100 ms if the device was not actually reset.
>
>> +
>> + if (ts->irq_gpio) {
>> + ret = devm_request_threaded_irq(dev, client->irq, NULL,
>> + axiom_irq, 0, dev_name(dev), ts);
>
> Did you mean to set IRQF_ONESHOT?
No
>
>> + if (ret < 0)
>> + return dev_err_probe(dev, ret, "Failed to request threaded
>> IRQ\n");
>> + }
>
> This is a kernel panic waiting to happen, as the interrupt handler
> (which can
> post input events) is declared before the input device has been
> allocated.
>
> Normally you want to set up interrupts last, after all resources have
> been
> initialized and the HW has been configured.
Ack thx.
>
>> +
>> + ret = axiom_discover(ts);
>> + if (ret)
>> + return dev_err_probe(dev, ret, "Failed touchscreen discover\n");
>> +
>> + ret = axiom_rebaseline(ts);
>> + if (ret)
>> + return dev_err_probe(dev, ret, "Failed touchscreen
>> re-baselining\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";
>> +
>> + /* Single Touch */
>> + input_set_abs_params(input_dev, ABS_X, 0, 65535, 0, 0);
>> + input_set_abs_params(input_dev, ABS_Y, 0, 65535, 0, 0);
>
> You don't need to explicitly declare support for single-contact axes;
> input_mt_init_slots() does this for us.
Indeed, we set INPUT_MT_DIRECT.
>
>> +
>> + /* Multi Touch */
>> + /* Min, Max, Fuzz (expected noise in px, try 4?) and Flat */
>> + input_set_abs_params(input_dev, ABS_MT_POSITION_X, 0, 65535, 0, 0);
>> + /* Min, Max, Fuzz (expected noise in px, try 4?) and Flat */
>> + 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);
>> +
>> + /* Registers the axiom device as a touchscreen instead of as a mouse
>> pointer */
>> + input_mt_init_slots(input_dev, AXIOM_U41_MAX_TARGETS,
>> INPUT_MT_DIRECT);
>
> Please check the return value of input_mt_init_slots().
OK.
>
>> +
>> + input_set_capability(input_dev, EV_KEY, BTN_LEFT);
>
> Why to hard-code the key to BTN_LEFT as opposed to making it
> configurable via
> device tree?
Not sure about this, I will check with the vendors, try to clarify why.
>
>> +
>> + /* 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);
>
> The driver is not posting any REL events. Can you clarify what is
> represented
> by MSC events?
Same here.
>
>> +
>> + if (!ts->irq_gpio) {
>> + ret = input_setup_polling(input_dev, axiom_i2c_poll);
>> + if (ret)
>> + return dev_err_probe(ts->dev, ret, "Unable to set up polling
>> mode\n");
>
> Nit: extraneous space.
>
>> + input_set_poll_interval(input_dev, POLL_INTERVAL_DEFAULT_MS);
>> + }
>> +
>> + 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 = TARGET_STATE_NOT_PRESENT;
>> +
>> + ret = input_register_device(input_dev);
>> +
>
> Nit: unnecessary NL.
>
>> + if (ret)
>> + return dev_err_probe(ts->dev, ret,
>> + "Could not register with Input Sub-system.\n");
>
> Nit: alignment.
>
>> +
>> + return 0;
>> +}
>> +
>> +static void axiom_i2c_remove(struct i2c_client *client)
>> +{
>> + struct axiom_data *ts = i2c_get_clientdata(client);
>> +
>> + input_unregister_device(ts->input_dev);
>> +}
>
> This remove callback is unnecessary. So long as input_dev was allocated
> using
> a device-managed function, it will be unregistered automatically.
>
>> +
>> +static const struct i2c_device_id axiom_i2c_id_table[] = {
>> + { "axiom-ax54a" },
>> + {},
>
> Nit: no need for a trailing comma after the sentinel, as no line would
> ever be
> added beneath it.
>
>> +};
>> +
>
> Nit: unnecessary NL.
>
>> +MODULE_DEVICE_TABLE(i2c, axiom_i2c_id_table);
>> +
>> +static const struct of_device_id axiom_i2c_of_match[] = {
>> + { .compatible = "touchnetix,axiom-ax54a", },
>> + {}
>> +};
>> +
>
> And here.
>
>> +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,
>> + .remove = axiom_i2c_remove,
>> +};
>> +
>> +module_i2c_driver(axiom_i2c_driver);
>
> And here.
>
>> +
>> +MODULE_AUTHOR("Bart Prescott <bartp@...sheep.co.uk>");
>> +MODULE_AUTHOR("Pedro Torruella <pedro.torruella@...chnetix.com>");
>> +MODULE_AUTHOR("Mark Satterthwaite
>> <mark.satterthwaite@...chnetix.com>");
>> +MODULE_AUTHOR("Hannah Rossiter <hannah.rossiter@...chnetix.com>");
>> +MODULE_AUTHOR("Kamel Bouhara <kamel.bouhara@...tlin.com>");
>> +MODULE_DESCRIPTION("TouchNetix aXiom touchscreen I2C bus driver");
>> +MODULE_LICENSE("GPL");
>> --
>> 2.25.1
>>
>
> Kind regards,
> Jeff LaBundy
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