Re: [PATCH v7 4/4] Input: Add TouchNetix aXiom I2C Touchscreen support
From: Andrew Thomas
Date: Thu Aug 20 2026 - 11:22:16 EST
Hi Marco,
On Fri, Jul 03, 2026 at 12:32:25AM +0200, Marco Felsch wrote:
This adds the initial support for the TouchNetix AX54A touchcontroller
which is part of TouchNetix's aXiom touchscreen controller family.
The TouchNetix aXiom family provides two physical interfaces: SPI and
I2C. This patch covers only the I2C interface.
Apart the input event handling the driver supports firmware updates too.
One firmware interface handles the touchcontroller firmware (AXFW)
update the other handles the touchcontroller configuration (TH2CFGBIN)
update.
Co-developed-by: Mamta Shukla <mamta.shukla@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Mamta Shukla <mamta.shukla@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Marco Felsch <m.felsch@xxxxxxxxxxxxxx>
---
.../testing/sysfs-driver-input-touchnetix-axiom | 80 +
drivers/input/touchscreen/Kconfig | 17 +
drivers/input/touchscreen/Makefile | 1 +
drivers/input/touchscreen/touchnetix_axiom.c | 3141 ++++++++++++++++++++
4 files changed, 3239 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-driver-input-touchnetix-axiom b/Documentation/ABI/testing/sysfs-driver-input-touchnetix-axiom
new file mode 100644
index 0000000000000000000000000000000000000000..8262673630557bf1e595a97ec23e66c1c5370f71
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-driver-input-touchnetix-axiom
@@ -0,0 +1,80 @@
+What: /sys/bus/i2c/devices/xxx/fw_major
+Date: Jan 2026
+Contact: linux-input@xxxxxxxxxxxxxxx
...
+
+What: /sys/bus/i2c/devices/xxx/fw_rc
+Date: Jan 2026
+Contact: linux-input@xxxxxxxxxxxxxxx
+Description:
+ Reports the firmware release canidate version provided by the touchscreen.
+
+ Access: Read
+
+ Valid values: Represented as string
+
+What: /sys/bus/i2c/devices/xxx/fw_status
+Date: Jan 2026
+Contact: linux-input@xxxxxxxxxxxxxxx
+Description:
+ Reports the firmware status provided by the touchscreen. It may
+ be either "release" or "engineering".
This is right, it is release. However in the driver you refer to "production",
which does not match.
+
+ Access: Read
+
...
+ * The devices have a 16bit ADC but Touchnetix used the lower two bits for other
+ * information.
+ */
+#define AXIOM_MAX_XY (65535 - 3)
This assumes ENABLECOORDINATESCALING is set in u41.
+#define AXIOM_DEFAULT_POLL_INTERVAL_MS 10
+#define AXIOM_PAGE_BYTE_LEN 256
+#define AXIOM_MAX_XFERLEN 0x7fff
+#define AXIOM_MAX_TOUCHSLOTS 10
+#define AXIOM_MAX_TOUCHSLOTS_MASK GENMASK(9, 0)
+
...
+ * same usage to handle different usage revisions.
+ *
+ * Note:
+ * During a th2cfgbin update the driver may use usages not listed here.
+ * Therefore the th2cfgbin update compares the current running FW again the
+ * th2cfgbin targets FW.
+ */
+static const struct axiom_usage_info driver_required_usages[] = {
Is this too strict?
Could you split it into "update" and "required"?
So a probe succeeds with "update" usages, so you can atleast get touch
reports, but a download is blocked without them.
Also should u64 be optional?
+ AXIOM_REPORT_USAGE(AXIOM_U01, 1, axiom_u01_rev1_process_report),
+ AXIOM_REPORT_USAGE(AXIOM_U01, 3, axiom_u01_rev1_process_report),
+ AXIOM_USAGE(AXIOM_U02, 1),
+ AXIOM_USAGE(AXIOM_U02, 2),
+ AXIOM_USAGE(AXIOM_U04, 1),
+ AXIOM_RO_USAGE(AXIOM_U31, 1),
+ AXIOM_RO_USAGE(AXIOM_U33, 2),
+ AXIOM_RO_USAGE(AXIOM_U33, 3),
+ AXIOM_RO_USAGE(AXIOM_U33, 6),
...
+
+ return entry->info->rev_num;
+}
+
+static bool axiom_driver_supports_usage(struct axiom_data *ts,
+ unsigned char usage_num)
This is called many times before calling a given usage handler.
Could we just check in axiom_u31_device_discover() or axiom_i2c_probe()
for all the required usages?
Could the "update" usages be checked in axiom_cfg/axfw_fw_prepare()?
+{
+ const struct axiom_usage_info *iter = driver_required_usages;
+ struct device *dev = ts->dev;
+ int rev;
+
+ /*
+ * Some features depend on the current running firmware. Don't print an
+ * error if the usage for an optional feature is missing.
+ */
+ if (!ts->usage_table[usage_num].populated) {
+ dev_dbg(dev, "u%02X is not supported by the current firmware\n",
+ usage_num);
+ return false;
+ }
+
+ rev = axiom_usage_rev(ts, usage_num);
+ if (rev < 0) {
+ dev_warn(dev, "Driver doesn't support u%02X yet\n", usage_num);
+ return false;
+ }
+
+ for (; iter; iter++) {
I assume this is supposed to be:
for (; iter->usage_num; iter++) {
+ if (iter->usage_num != usage_num)
+ continue;
+
+ if (iter->rev_num == rev)
+ return true;
+ }
+
+ dev_warn(dev, "Driver doesn't support u%02X rev.%d yet\n",
+ usage_num, rev);
+
+ return false;
+}
+
...
+
+ /*
+ * Downstream axcfg.py waits for 1sec without checking U01 HELLO. Tests
+ * showed that waiting for the HELLO message isn't enough therefore we
+ * need to add the additional fsleep(1sec).
+ * Touchnetix said that the boot can take up to 2sec if all self tests
+ * are enabled, so wait 2sec for the HELLO message.
+ */
+ if (!axiom_wait_for_completion_timeout(ts, &ts->boot_complete,
+ msecs_to_jiffies(2 * MSEC_PER_SEC))) {
+ dev_err(ts->dev, "Error swreset timedout\n");
+ error = -ETIMEDOUT;
+ }
There is no reinit_completion() to go after/before wait_for_completion_timeout() for any of the calls.
From my understanding this must be called before starting the new wait for completion.
The 2s timeout may have hidden this.
+
+ fsleep(USEC_PER_SEC);
+
+ return error;
+}
+
...
+ crc_report = get_unaligned_le16(&buf[len - 2]);
+ crc_calc = crc16(0, buf, (len - 2));
+
+ if (crc_calc != crc_report) {
+ dev_err_ratelimited(dev, "CRC16 mismatch!\n");
+ return -EINVAL;
+ }
+
+ report_usage = buf[1];
+ payload = &buf[AXIOM_U34_REV1_PREAMBLE_BYTES];
+ len -= AXIOM_U34_REV1_PREAMBLE_BYTES - AXIOM_U34_REV1_POSTAMBLE_BYTES;
Is this right?
Should it not be:
len -= AXIOM_U34_REV1_PREAMBLE_BYTES;
len -= AXIOM_U34_REV1_POSTAMBLE_BYTES;
+
+ switch (report_usage) {
+ case AXIOM_U01:
+ case AXIOM_U41:
+ /*
+ * axiom_driver_supports_usage() is not required since the
+ * correct .process_report() hooks are assigned during the
+ * discovery.
+ */
+ return axiom_process_report(ts, report_usage, payload, len);
+ default:
+ dev_dbg(dev, "Unsupported report u%02X received\n",
+ report_usage);
+ }
+
+ return 0;
+}
+
...
+static int axiom_u41_rev2_process_report(struct axiom_data *ts,
+ const u8 *buf, size_t bufsize)
+{
+ struct input_dev *input = ts->input;
+ unsigned char id;
+ u16 targets;
+
+ /*
+ * The input registration can be postponed but the touchscreen FW is
+ * sending u41 reports regardless.
+ */
+ if (!input)
+ return 0;
+
+ targets = get_unaligned_le16(&buf[AXIOM_U41_REV2_TARGETSTATUS_REG]);
+
+ for_each_set_bit(id, &ts->enabled_slots, AXIOM_MAX_TOUCHSLOTS) {
+ bool present;
+ u16 x, y;
+ s8 z;
+
+ axiom_u41_rev2_decode_target(buf, id, &x, &y, &z);
+
+ present = targets & BIT(id);
+ /* Ignore possible jitters */
+ if (z == AXIOM_PROX_LEVEL)
+ present = false;
+
+ dev_dbg(ts->dev, "id:%u x:%u y:%u z:%d present:%u",
+ id, x, y, z, present);
+
+ input_mt_slot(input, id);
The index in enabled_slots can be greater than num_slots since u42 does not neccesarily
therefore this can send an out of range finger.
+ if (input_mt_report_slot_state(input, MT_TOOL_FINGER, present))
+ touchscreen_report_pos(input, &ts->prop, x, y, true);
+
+ if (!present)
+ continue;
+
+ input_report_abs(input, ABS_MT_DISTANCE, z < 0 ? -z : 0);
+ if (ts->cds_enabled)
+ input_report_abs(input, ABS_MT_PRESSURE, z >= 0 ? z : 0);
+ }
+
+ input_sync(input);
+
+ return 0;
+}
+
+static int axiom_u01_rev1_process_report(struct axiom_data *ts,
+ const u8 *buf, size_t bufsize)
+{
+ switch (buf[AXIOM_U01_REV1_REPORTTYPE_REG]) {
+ case AXIOM_U01_REV1_REPORTTYPE_HELLO:
+ dev_dbg(ts->dev, "u01 HELLO received\n");
+ axiom_complete(ts, &ts->boot_complete);
+ return 0;
+ case AXIOM_U01_REV1_REPORTTYPE_HEARTBEAT:
+ dev_dbg_ratelimited(ts->dev, "u01 HEARTBEAT received\n");
+ return 0;
+ case AXIOM_U01_REV1_REPORTTYPE_OPCOMPLETE:
+ dev_dbg(ts->dev, "u01 OPCOMPLETE received\n");
+ axiom_u02_handshakenvm(ts);
+ axiom_complete(ts, &ts->nvm_write);
+ return 0;
+ default:
+ return -EINVAL;
+ }
+}
+
...
+
+ /*
+ * Ensure that the IRQ setup is done only once since the handler belong
+ * to the i2c-dev whereas the input-poller belong to the input-dev. The
+ * input-dev can get unregistered during a firmware update to reflect
+ * the new firmware state. Therefore the input-poller setup must be done
+ * always.
+ */
+ if (client->irq) {
+ if (!ts->irq_setup_done) {
+ error = devm_request_threaded_irq(dev, client->irq,
+ NULL, axiom_irq,
+ IRQF_ONESHOT,
+ dev_name(dev), ts);
+ if (error) {
+ dev_err(dev, "Failed to request IRQ\n");
input_free_device() should be called.
+ return error;
+ }
+ ts->irq_setup_done = true;
+ }
+ } else {
+ error = input_setup_polling(input, axiom_poll);
+ if (error) {
+ input_free_device(input);
+ dev_err(dev, "Setup polling mode failed\n");
+ return error;
+ }
+
+ input_set_poll_interval(input, ts->poll_interval);
+ }
+
+ input_set_drvdata(input, ts);
+ ts->input = input;
+
+ error = input_register_device(input);
+ if (error) {
+ input_free_device(input);
+ ts->input = NULL;
+ dev_err(dev, "Failed to register input device\n");
+ };
+
+ return error;
+}
+
+static int axiom_update_input_dev(struct axiom_data *ts)
+{
+ axiom_unregister_input_dev(ts);
+
+ return axiom_register_input_dev(ts, true);
+}
+
+static int axiom_parse_firmware(struct axiom_data *ts)
+{
+ struct device *dev = ts->dev;
+ struct gpio_desc *gpio;
+ int error;
+
+ ts->supplies[0].supply = "vddi";
+ ts->supplies[1].supply = "vdda";
+ ts->num_supplies = ARRAY_SIZE(ts->supplies);
+
+ error = devm_regulator_bulk_get(dev, ts->num_supplies, ts->supplies);
+ if (error)
+ return dev_err_probe(dev, error,
+ "Failed to get power supplies\n");
+
+ gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+ if (IS_ERR(gpio))
+ return dev_err_probe(dev, PTR_ERR(gpio),
+ "Failed to get reset GPIO\n");
+ ts->reset_gpio = gpio;
+
+ ts->poll_interval = AXIOM_DEFAULT_POLL_INTERVAL_MS;
+ device_property_read_u32(dev, "poll-interval", &ts->poll_interval);
+
+ return 0;
+}
+
+static int axiom_power_up_device(struct axiom_data *ts)
+{
+ struct device *dev = ts->dev;
+ int error;
+
+ error = regulator_bulk_enable(ts->num_supplies, ts->supplies);
+ if (error) {
+ dev_err(dev, "Failed to enable power supplies\n");
+ return error;
+ }
+
+ gpiod_set_value_cansleep(ts->reset_gpio, 1);
+ fsleep(2000);
+ gpiod_set_value_cansleep(ts->reset_gpio, 0);
+
+ fsleep(AXIOM_STARTUP_TIME_MS);
+
+ 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_of_match[] = {
+ { .compatible = "touchnetix,ax54a", },
+ { }
+};
+MODULE_DEVICE_TABLE(of, axiom_of_match);
This also works for ax80a. ax54 and ax80 are the same silicon but with a
different pinout. It is up to you if you wish to add this.
+
+static struct i2c_driver axiom_i2c_driver = {
+ .driver = {
+ .name = KBUILD_MODNAME,
+ .dev_groups = axiom_groups,
+ .pm = pm_ptr(&axiom_pm_ops),
+ .of_match_table = axiom_of_match,
+ },
+ .id_table = axiom_i2c_id_table,
+ .probe = axiom_i2c_probe,
+ .remove = axiom_i2c_remove,
+};
+module_i2c_driver(axiom_i2c_driver);
+
+MODULE_DESCRIPTION("TouchNetix aXiom touchscreen I2C bus driver");
+MODULE_LICENSE("GPL");
--
2.47.3
Apologies for the delay in review.
I have tested with ax80a and ax198a and everything works as intended
on both of them.
This version looks to be quite reliable for the firmware/config download which is great!
Tested-by: Andrew Thomas <andrew.thomas@xxxxxxxxxxxxxx
Regards,
Andrew