[PATCH v4 0/3] Introduce EC driver for Snapdragon X1E based Dell XPS 13 9345

[PATCH v4 0/3] Introduce EC driver for Snapdragon X1E based Dell XPS 13 9345

[Aleksandrs Vinarskis]

This series adds Embedded Controller (EC) driver for Dell XPS 13 9345.
While EC appears to control most of device's peripherals, particular
driver addresses power and thermal managment issues. Key operational
principle involves initial thermistor constants configuration followed
by a periodic reporting of these onboard thermistor values from across
the motherboard to the EC. The latter then handles fan ramp-up/
ramp-down internally. Suspend/Resume must be likewise propagated to EC
for power management.

The driver was developed primarily by analyzing ACPI DSDT's _DSM and
i2c dumps of communication between SoC and EC during various stages of
operation (bootup, suspend, resume).

With EC driver in place, the following issues are addressed:
1. Fans were not properly cooling the laptop, would kick in late and
   spin lazily, resulting in heavy throttling. With EC driver fans
   start sooner and hit high RPM under heavy load.
2. Fans were not stopping once SoC temperature dropped, they would keep
   slowly spinning irrespective of suspend and/or closed lid until the
   next powercycle. With EC driver shortly after SoC temperature drops,
   thermistors temperature drops, and fans ramp-down.
3. Keyboard and touch row backlight were not turning off during
   suspend - only lid close would power off the touch row. With EC
   driver behavior matches that of Windows, suspending device with lid
   open powers off the peripherals.

As thermistor readout depends on pmic's ADCs, this series introduces
EC driver and its schema, adds missing ADC to hamoa-pmics, and finally
adds thermistor and EC nodes to x1e80100-dell-xps13-9345.dts.

Additional findings:
- Max fan speed depends on Dell's power mode settings, configurable in
  BIOS or using Windows app (relies on ACPI-WMI). It appears best
  cooling performance is achieved under 'Ultra Performance' profile.
- When the said power mode is changed using Windows app, EC IRQ is
  triggered. Windows performs what appears to be thermistor contants
  readout, though its not obvious what it is used for.
- Given similarities between Dell XPS 13 series (codename 'tributo')
  and Snapdragon-based Latitude, Inspiron ('thena'), including matching
  EC address and response to suspend/resume command the EC driver can
  be likely used for both, though in-depth testing on 'thena' is
  required.

This series depends on QCOM SPMI PMIC5 Gen3 ADC [1], which was added to
`linux-next` for v7.1, but must be picked if this series to be backported.

[1] https://lore.kernel.org/all/20260209105438.596339-1-jishnu.prakash@oss.qualcomm.com/

Signed-off-by: Aleksandrs Vinarskis <alex@vinarskis.com>
---
Changes in v4:
- Change to .data struct provided via compatible, which contains expected
  thermistor arrangement and magic init sequence to make it easier to
  support new systems as per Bryan
- Change milicelsius spelling, add newline, return as per Bryan
- Link to v3: https://lore.kernel.org/r/20260801-dell-xps-9345-ec-v3-0-9f4bdb5a5dad@vinarskis.com

Changes in v3:
- Rebase on latest linux-next
- Add Neil, Stephan to CC, as they worked on ADC for PMK8550
- Drop VADC for pmk8550 as it was already merged upstream
- Rename PMK8550 registers to use newly upstreamed headers for ADC5_GEN3
  in both dt-bindings, device-tree patches
- Rename ADC labels to have meaningful for user names as per Bryan
- Drop Dmitry's RB from last patch since it was almost completely changed
  now
- Link to v2: https://lore.kernel.org/r/20260404-dell-xps-9345-ec-v2-0-c977c3caa81f@vinarskis.com

Changes in v2:
- Update cover letter to indicate dependency on QCOM ADC series, only
  relevant for backporting
- Update description of dell_xps_ec_suspend: entering suspend does not
  necessarily ramp down the fans, if thermistors still report high temps
- Add die_temp/xo_therm to pmk8550 as per Konrad Dybcio
- Add missing header imports as per Ilpo Järvinen
- Add explanation for EC reset pin being reserved
- Fix device-tree: minor issues as per Konrad Dybcio
- Fix device-tree: alingment issues as per Konrad Dybcio
- Fix driver: alingment issues as per Bjorn Andersson
- Fix driver: handle temp value as 16bit register as per Ilpo Järvinen
- Fix bindigs: description and example as per Krzysztof Kozlowski 
- Link to v1: https://lore.kernel.org/r/20260401-dell-xps-9345-ec-v1-0-afa5cacd49be@vinarskis.com

---
Aleksandrs Vinarskis (3):
      dt-bindings: platform: introduce EC for Dell XPS 13 9345
      platform: arm64: dell-xps-ec: new driver
      arm64: dts: qcom: x1e80100-dell-xps13-9345: introduce EC

 .../embedded-controller/dell,xps13-9345-ec.yaml    |  91 +++++++
 MAINTAINERS                                        |   6 +
 .../boot/dts/qcom/x1e80100-dell-xps13-9345.dts     |  86 +++++-
 drivers/platform/arm64/Kconfig                     |  12 +
 drivers/platform/arm64/Makefile                    |   1 +
 drivers/platform/arm64/dell-xps-ec.c               | 299 +++++++++++++++++++++
 6 files changed, 493 insertions(+), 2 deletions(-)
---
base-commit: 115cd2ef86146afa47f363fedf97890575abcca4
change-id: 20260331-dell-xps-9345-ec-e5f49d1bef61

Best regards,
-- 
Aleksandrs Vinarskis <alex@vinarskis.com>

[PATCH v4 1/3] dt-bindings: platform: introduce EC for Dell XPS 13 9345

[Aleksandrs Vinarskis]

Add bindings for Embedded Controller (EC) in Dell XPS 13 9345 (platform
codename 'tributo'). It may be partially or fully compatible with EC
found in Snapdragon-based Dell Latitude, Inspiron ('thena').

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Signed-off-by: Aleksandrs Vinarskis <alex@vinarskis.com>
---
 .../embedded-controller/dell,xps13-9345-ec.yaml    | 91 ++++++++++++++++++++++
 MAINTAINERS                                        |  5 ++
 2 files changed, 96 insertions(+)

diff --git a/Documentation/devicetree/bindings/embedded-controller/dell,xps13-9345-ec.yaml b/Documentation/devicetree/bindings/embedded-controller/dell,xps13-9345-ec.yaml
new file mode 100644
index 000000000000..3485117b505c
--- /dev/null
+++ b/Documentation/devicetree/bindings/embedded-controller/dell,xps13-9345-ec.yaml
@@ -0,0 +1,91 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/embedded-controller/dell,xps13-9345-ec.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Dell XPS 13 9345 Embedded Controller
+
+maintainers:
+  - Aleksandrs Vinarskis <alex@vinarskis.com>
+
+description:
+  The Dell XPS 13 9345 has an Embedded Controller (EC) which handles thermal
+  and power management. It is communicating with SoC over multiple i2c busses.
+  Among other things, it handles fan speed control, thermal shutdown, peripheral
+  power supply including trackpad, touch-row, display. For these functions, it
+  requires frequently updated thermal readings from onboard thermistors.
+
+properties:
+  compatible:
+    const: dell,xps13-9345-ec
+
+  reg:
+    const: 0x3b
+
+  interrupts:
+    maxItems: 1
+
+  io-channels:
+    description:
+      ADC channels connected to the 7 onboard thermistors on PMK8550.
+      EC requires frequent thermal readings of these channels to perform
+      automated fan speed control.
+    items:
+      - description: ADC channel for sys_therm0
+      - description: ADC channel for sys_therm1
+      - description: ADC channel for sys_therm2
+      - description: ADC channel for sys_therm3
+      - description: ADC channel for sys_therm4
+      - description: ADC channel for sys_therm5
+      - description: ADC channel for sys_therm6
+
+  io-channel-names:
+    items:
+      - const: sys_therm0
+      - const: sys_therm1
+      - const: sys_therm2
+      - const: sys_therm3
+      - const: sys_therm4
+      - const: sys_therm5
+      - const: sys_therm6
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - io-channels
+  - io-channel-names
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    #include <arm64/qcom/qcom-adc5-gen3.h>
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        embedded-controller@3b {
+            compatible = "dell,xps13-9345-ec";
+            reg = <0x3b>;
+            interrupts-extended = <&tlmm 66 IRQ_TYPE_LEVEL_LOW>;
+
+            io-channels = <&pmk8550_vadc ADC5_GEN3_AMUX3_GPIO_100K_PU(1)>,
+                          <&pmk8550_vadc ADC5_GEN3_AMUX4_GPIO_100K_PU(1)>,
+                          <&pmk8550_vadc ADC5_GEN3_AMUX1_THM_100K_PU(1)>,
+                          <&pmk8550_vadc ADC5_GEN3_AMUX2_THM_100K_PU(1)>,
+                          <&pmk8550_vadc ADC5_GEN3_AMUX3_THM_100K_PU(1)>,
+                          <&pmk8550_vadc ADC5_GEN3_AMUX4_THM_100K_PU(1)>,
+                          <&pmk8550_vadc ADC5_GEN3_AMUX5_THM_100K_PU(1)>;
+            io-channel-names = "sys_therm0",
+                               "sys_therm1",
+                               "sys_therm2",
+                               "sys_therm3",
+                               "sys_therm4",
+                               "sys_therm5",
+                               "sys_therm6";
+        };
+    };
+...
diff --git a/MAINTAINERS b/MAINTAINERS
index 6008f16ae2ca..9b238f14f0be 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7348,6 +7348,11 @@ S:	Maintained
 F:	Documentation/ABI/testing/sysfs-class-firmware-attributes
 F:	drivers/platform/x86/dell/dell-wmi-sysman/
 
+DELL XPS EMBEDDED CONTROLLER DRIVER
+M:	Aleksandrs Vinarskis <alex@vinarskis.com>
+S:	Maintained
+F:	Documentation/devicetree/bindings/embedded-controller/dell,xps13-9345-ec.yaml
+
 DELTA AHE-50DC FAN CONTROL MODULE DRIVER
 M:	Zev Weiss <zev@bewilderbeest.net>
 L:	linux-hwmon@vger.kernel.org

-- 
2.54.0

[PATCH v4 2/3] platform: arm64: dell-xps-ec: new driver

[Aleksandrs Vinarskis]

Introduce EC driver for Dell XPS 13 9345 (codename 'tributo') which may
partially of fully compatible with Snapdragon-based Dell Latitude,
Inspiron ('thena'). Primary function of this driver is unblock EC's
thermal management, specifically to provide it with necessary
information to control device fans, peripherals power.

The driver was developed primarily by analyzing ACPI DSDT's _DSM and
i2c dumps of communication between SoC and EC. Changes to Windows
driver's behavior include increasing temperature feed loop from ~50ms
to 100ms here.

While Xps's EC is rather complex and controls practically all device
peripherals including touch row's brightness and special keys such as
mic mute, these do not go over this particular i2c interface.

Not yet implemented features:
- On lid-close IRQ event is registered. Windows performs what to
  appears to be thermistor constants readout, though its not obvious
  what it used for.
- According to ACPI's _DSM there is a method to readout fans' RPM.
- Initial thermistor constants were sniffed from Windows, these can be
  likely fine tuned for better cooling performance.
- There is additional temperature reading that Windows sents to EC but
  more rare than others, likely SoC T_j / TZ98 or TZ4. This is the only
  thermal zone who's reading can exceed 115C without triggering thermal
  shutdown.
- Given similarities between 'tributo' and 'thena' platforms, including
  EC i2c address, driver can be potentially extended to support both.

Signed-off-by: Aleksandrs Vinarskis <alex@vinarskis.com>
---
 MAINTAINERS                          |   1 +
 drivers/platform/arm64/Kconfig       |  12 ++
 drivers/platform/arm64/Makefile      |   1 +
 drivers/platform/arm64/dell-xps-ec.c | 299 +++++++++++++++++++++++++++++++++++
 4 files changed, 313 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 9b238f14f0be..ad5231846493 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7352,6 +7352,7 @@ DELL XPS EMBEDDED CONTROLLER DRIVER
 M:	Aleksandrs Vinarskis <alex@vinarskis.com>
 S:	Maintained
 F:	Documentation/devicetree/bindings/embedded-controller/dell,xps13-9345-ec.yaml
+F:	drivers/platform/arm64/dell-xps-ec.c
 
 DELTA AHE-50DC FAN CONTROL MODULE DRIVER
 M:	Zev Weiss <zev@bewilderbeest.net>
diff --git a/drivers/platform/arm64/Kconfig b/drivers/platform/arm64/Kconfig
index e32e01b2a9bd..29416f8d7232 100644
--- a/drivers/platform/arm64/Kconfig
+++ b/drivers/platform/arm64/Kconfig
@@ -33,6 +33,18 @@ config EC_ACER_ASPIRE1
 	  laptop where this information is not properly exposed via the
 	  standard ACPI devices.
 
+config EC_DELL_XPS
+	tristate "Dell XPS 9345 Embedded Controller driver"
+	depends on ARCH_QCOM || COMPILE_TEST
+	depends on I2C
+	depends on IIO
+	help
+	  Driver for the Embedded Controller in the Qualcomm Snapdragon-based
+	  Dell XPS 13 9345, which handles thermal management and fan speed
+	  control.
+
+	  Say M or Y here to include this support.
+
 config EC_HUAWEI_GAOKUN
 	tristate "Huawei Matebook E Go Embedded Controller driver"
 	depends on ARCH_QCOM || COMPILE_TEST
diff --git a/drivers/platform/arm64/Makefile b/drivers/platform/arm64/Makefile
index 7681be4a46e9..669dc9e79afb 100644
--- a/drivers/platform/arm64/Makefile
+++ b/drivers/platform/arm64/Makefile
@@ -6,6 +6,7 @@
 #
 
 obj-$(CONFIG_EC_ACER_ASPIRE1)	+= acer-aspire1-ec.o
+obj-$(CONFIG_EC_DELL_XPS)	+= dell-xps-ec.o
 obj-$(CONFIG_EC_HUAWEI_GAOKUN)	+= huawei-gaokun-ec.o
 obj-$(CONFIG_EC_LENOVO_YOGA_C630) += lenovo-yoga-c630.o
 obj-$(CONFIG_EC_LENOVO_THINKPAD_T14S) += lenovo-thinkpad-t14s.o
diff --git a/drivers/platform/arm64/dell-xps-ec.c b/drivers/platform/arm64/dell-xps-ec.c
new file mode 100644
index 000000000000..695a7d01acd6
--- /dev/null
+++ b/drivers/platform/arm64/dell-xps-ec.c
@@ -0,0 +1,299 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2026, Aleksandrs Vinarskis <alex@vinarskis.com>
+ */
+
+#include <linux/array_size.h>
+#include <linux/dev_printk.h>
+#include <linux/device.h>
+#include <linux/devm-helpers.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/iio/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/overflow.h>
+#include <linux/pm.h>
+#include <linux/types.h>
+#include <linux/unaligned.h>
+#include <linux/workqueue.h>
+
+#define DELL_XPS_EC_SUSPEND_CMD		0xb9
+#define DELL_XPS_EC_SUSPEND_MSG_LEN	64
+
+#define DELL_XPS_EC_TEMP_CMD0		0xfb
+#define DELL_XPS_EC_TEMP_CMD1		0x20
+#define DELL_XPS_EC_TEMP_CMD3		0x02
+#define DELL_XPS_EC_TEMP_MSG_LEN	6
+#define DELL_XPS_EC_TEMP_POLL_JIFFIES	msecs_to_jiffies(100)
+
+/*
+ * Mapping between IIO channel name (as per schematics) and EC command byte
+ */
+struct dell_xps_ec_therm {
+	const char *name;
+	u8 cmd;
+};
+
+struct dell_xps_ec_data {
+	const struct dell_xps_ec_therm *therms;
+	unsigned int num_therms;
+	const u8 *profile;
+	size_t profile_len;
+};
+
+/*
+ * Format:
+ * - header/unknown (2 bytes)
+ * - per-thermistor entries (3 bytes): thermistor_id, param1, param2
+ */
+static const u8 dell_xps13_9345_thermistor_profile[] = {
+	0xff, 0x54,
+	0x01, 0x00, 0x2b,	/* sys_therm0 */
+	0x02, 0x44, 0x2a,	/* sys_therm1 */
+	0x03, 0x44, 0x2b,	/* sys_therm2 */
+	0x04, 0x44, 0x28,	/* sys_therm3 */
+	0x05, 0x55, 0x2a,	/* sys_therm4 */
+	0x06, 0x44, 0x26,	/* sys_therm5 */
+	0x07, 0x44, 0x2b,	/* sys_therm6 */
+};
+
+static const struct dell_xps_ec_therm dell_xps13_9345_therms[] = {
+	/* TODO: 0x01 is sent only occasionally, likely TZ98 or TZ4 */
+	{ "sys_therm0", 0x02 },
+	{ "sys_therm1", 0x03 },
+	{ "sys_therm2", 0x04 },
+	{ "sys_therm3", 0x05 },
+	{ "sys_therm4", 0x06 },
+	{ "sys_therm5", 0x07 },
+	{ "sys_therm6", 0x08 },
+};
+
+static const struct dell_xps_ec_data dell_xps13_9345_data = {
+	.therms = dell_xps13_9345_therms,
+	.num_therms = ARRAY_SIZE(dell_xps13_9345_therms),
+	.profile = dell_xps13_9345_thermistor_profile,
+	.profile_len = sizeof(dell_xps13_9345_thermistor_profile),
+};
+
+struct dell_xps_ec {
+	struct device *dev;
+	struct i2c_client *client;
+	const struct dell_xps_ec_data *data;
+	struct delayed_work temp_work;
+	unsigned int num_therms;
+	struct iio_channel *therm_channels[] __counted_by(num_therms);
+};
+
+static int dell_xps_ec_suspend_cmd(struct dell_xps_ec *ec, bool suspend)
+{
+	u8 buf[DELL_XPS_EC_SUSPEND_MSG_LEN] = {};
+	int ret;
+
+	buf[0] = DELL_XPS_EC_SUSPEND_CMD;
+	buf[1] = suspend ? 0x01 : 0x00;
+	/* bytes 2..63 remain zero */
+
+	ret = i2c_master_send(ec->client, buf, sizeof(buf));
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int dell_xps_ec_send_temp(struct dell_xps_ec *ec, u8 cmd_byte,
+				 int milli_celsius)
+{
+	u8 buf[DELL_XPS_EC_TEMP_MSG_LEN];
+	u16 deci_celsius;
+	int ret;
+
+	/* Convert millicelsius to decicelsius */
+	deci_celsius = milli_celsius / 100;
+
+	buf[0] = DELL_XPS_EC_TEMP_CMD0;
+	buf[1] = DELL_XPS_EC_TEMP_CMD1;
+	buf[2] = cmd_byte;
+	buf[3] = DELL_XPS_EC_TEMP_CMD3;
+	put_unaligned_le16(deci_celsius, &buf[4]);
+
+	ret = i2c_master_send(ec->client, buf, sizeof(buf));
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static void dell_xps_ec_temp_work_fn(struct work_struct *work)
+{
+	struct dell_xps_ec *ec = container_of(work, struct dell_xps_ec,
+					      temp_work.work);
+	const struct dell_xps_ec_therm *therms = ec->data->therms;
+	int val, ret;
+	unsigned int i;
+
+	for (i = 0; i < ec->num_therms; i++) {
+		if (!ec->therm_channels[i])
+			continue;
+
+		ret = iio_read_channel_processed(ec->therm_channels[i], &val);
+		if (ret < 0) {
+			dev_err_ratelimited(ec->dev,
+					    "Failed to read thermistor %s: %d\n",
+					    therms[i].name, ret);
+			continue;
+		}
+
+		ret = dell_xps_ec_send_temp(ec, therms[i].cmd, val);
+		if (ret < 0) {
+			dev_err_ratelimited(ec->dev,
+					    "Failed to send temp for %s: %d\n",
+					    therms[i].name, ret);
+		}
+	}
+
+	schedule_delayed_work(&ec->temp_work, DELL_XPS_EC_TEMP_POLL_JIFFIES);
+}
+
+static irqreturn_t dell_xps_ec_irq_handler(int irq, void *data)
+{
+	struct dell_xps_ec *ec = data;
+
+	/*
+	 * TODO: IRQ is fired on lid-close. Follow Windows example to read out
+	 *       the thermistor thresholds and potentially fan speeds.
+	 */
+	dev_info_ratelimited(ec->dev, "IRQ triggered! (irq=%d)\n", irq);
+
+	return IRQ_HANDLED;
+}
+
+static int dell_xps_ec_probe(struct i2c_client *client)
+{
+	const struct dell_xps_ec_data *data;
+	struct device *dev = &client->dev;
+	struct dell_xps_ec *ec;
+	unsigned int i;
+	int ret;
+
+	data = i2c_get_match_data(client);
+	if (!data)
+		return dev_err_probe(dev, -ENODEV, "No match data\n");
+
+	ec = devm_kzalloc(dev, struct_size(ec, therm_channels, data->num_therms),
+			  GFP_KERNEL);
+	if (!ec)
+		return -ENOMEM;
+
+	ec->dev = dev;
+	ec->client = client;
+	ec->data = data;
+	ec->num_therms = data->num_therms;
+	i2c_set_clientdata(client, ec);
+
+	/* Set default thermistor profile */
+	ret = i2c_master_send(client, data->profile, data->profile_len);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Failed to set thermistor profile\n");
+
+	/* Get IIO channels for thermistors */
+	for (i = 0; i < ec->num_therms; i++) {
+		ec->therm_channels[i] =
+			devm_iio_channel_get(dev, data->therms[i].name);
+		if (IS_ERR(ec->therm_channels[i])) {
+			ret = PTR_ERR(ec->therm_channels[i]);
+			ec->therm_channels[i] = NULL;
+			if (ret == -EPROBE_DEFER)
+				return ret;
+			dev_warn(dev, "Thermistor %s not available: %d\n",
+				 data->therms[i].name, ret);
+		}
+	}
+
+	/* Start periodic temperature reporting */
+	ret = devm_delayed_work_autocancel(dev, &ec->temp_work,
+					   dell_xps_ec_temp_work_fn);
+	if (ret)
+		return ret;
+	schedule_delayed_work(&ec->temp_work, DELL_XPS_EC_TEMP_POLL_JIFFIES);
+	dev_dbg(dev, "Started periodic temperature reporting to EC every %d ms\n",
+		jiffies_to_msecs(DELL_XPS_EC_TEMP_POLL_JIFFIES));
+
+	/* Request IRQ for EC events */
+	ret = devm_request_threaded_irq(dev, client->irq, NULL,
+					dell_xps_ec_irq_handler,
+					IRQF_ONESHOT, dev_name(dev), ec);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to request IRQ\n");
+
+	return 0;
+}
+
+/*
+ * Notify EC of suspend
+ *
+ * This will:
+ * - Cut power to display/trackpad/keyboard/touchrow, wake-up source still works
+ */
+static int dell_xps_ec_suspend(struct device *dev)
+{
+	struct dell_xps_ec *ec = dev_get_drvdata(dev);
+
+	cancel_delayed_work_sync(&ec->temp_work);
+
+	return dell_xps_ec_suspend_cmd(ec, true);
+}
+
+/*
+ * Notify EC of resume
+ *
+ * This will undo the suspend actions
+ * Without the resume signal, device would wake up but be forced back into
+ * suspend by EC within seconds
+ */
+static int dell_xps_ec_resume(struct device *dev)
+{
+	struct dell_xps_ec *ec = dev_get_drvdata(dev);
+	int ret;
+
+	ret = dell_xps_ec_suspend_cmd(ec, false);
+	if (ret)
+		return ret;
+
+	schedule_delayed_work(&ec->temp_work, DELL_XPS_EC_TEMP_POLL_JIFFIES);
+
+	return 0;
+}
+
+static const struct of_device_id dell_xps_ec_of_match[] = {
+	{ .compatible = "dell,xps13-9345-ec", .data = &dell_xps13_9345_data },
+	{}
+};
+MODULE_DEVICE_TABLE(of, dell_xps_ec_of_match);
+
+static const struct i2c_device_id dell_xps_ec_i2c_id[] = {
+	{ "dell-xps-ec", (kernel_ulong_t)&dell_xps13_9345_data },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, dell_xps_ec_i2c_id);
+
+static const struct dev_pm_ops dell_xps_ec_pm_ops = {
+	SYSTEM_SLEEP_PM_OPS(dell_xps_ec_suspend, dell_xps_ec_resume)
+};
+
+static struct i2c_driver dell_xps_ec_driver = {
+	.driver = {
+		.name = "dell-xps-ec",
+		.of_match_table = dell_xps_ec_of_match,
+		.pm = &dell_xps_ec_pm_ops,
+	},
+	.probe = dell_xps_ec_probe,
+	.id_table = dell_xps_ec_i2c_id,
+};
+module_i2c_driver(dell_xps_ec_driver);
+
+MODULE_AUTHOR("Aleksandrs Vinarskis <alex@vinarskis.com>");
+MODULE_DESCRIPTION("Dell XPS 13 9345 Embedded Controller");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("IIO_CONSUMER");

-- 
2.54.0

[PATCH v4 3/3] arm64: dts: qcom: x1e80100-dell-xps13-9345: introduce EC

[Aleksandrs Vinarskis]

Describe embedded controller, its interrupt and required thermal zones.
Add EC's reset GPIO to reserved range, as triggering it during device
operation leads to unrecoverable and unusable state.

Signed-off-by: Aleksandrs Vinarskis <alex@vinarskis.com>
---
 .../boot/dts/qcom/x1e80100-dell-xps13-9345.dts     | 86 +++++++++++++++++++++-
 1 file changed, 84 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/boot/dts/qcom/x1e80100-dell-xps13-9345.dts b/arch/arm64/boot/dts/qcom/x1e80100-dell-xps13-9345.dts
index 2be5a37c00cc..2b5b9061c56f 100644
--- a/arch/arm64/boot/dts/qcom/x1e80100-dell-xps13-9345.dts
+++ b/arch/arm64/boot/dts/qcom/x1e80100-dell-xps13-9345.dts
@@ -759,8 +759,32 @@ retimer_ss0_con_sbu_out: endpoint {
 
 &i2c5 {
 	clock-frequency = <100000>;
-	status = "disabled";
-	/* EC @0x3b */
+	status = "okay";
+
+	embedded-controller@3b {
+		compatible = "dell,xps13-9345-ec";
+		reg = <0x3b>;
+
+		interrupts-extended = <&tlmm 66 IRQ_TYPE_LEVEL_LOW>;
+
+		pinctrl-0 = <&ec_int_n_default>;
+		pinctrl-names = "default";
+
+		io-channels = <&pmk8550_vadc ADC5_GEN3_AMUX3_GPIO_100K_PU(1)>,
+			      <&pmk8550_vadc ADC5_GEN3_AMUX4_GPIO_100K_PU(1)>,
+			      <&pmk8550_vadc ADC5_GEN3_AMUX1_THM_100K_PU(1)>,
+			      <&pmk8550_vadc ADC5_GEN3_AMUX2_THM_100K_PU(1)>,
+			      <&pmk8550_vadc ADC5_GEN3_AMUX3_THM_100K_PU(1)>,
+			      <&pmk8550_vadc ADC5_GEN3_AMUX4_THM_100K_PU(1)>,
+			      <&pmk8550_vadc ADC5_GEN3_AMUX5_THM_100K_PU(1)>;
+		io-channel-names = "sys_therm0",
+				   "sys_therm1",
+				   "sys_therm2",
+				   "sys_therm3",
+				   "sys_therm4",
+				   "sys_therm5",
+				   "sys_therm6";
+	};
 };
 
 &i2c7 {
@@ -1025,6 +1049,57 @@ rtmr0_1p8_reg_en: rtmr0-1p8-reg-en-state {
 	};
 };
 
+&pmk8550_vadc {
+	sys_therm0: channel@14c {
+		reg = <ADC5_GEN3_AMUX3_GPIO_100K_PU(1)>;
+		qcom,hw-settle-time = <200>;
+		qcom,ratiometric;
+		label = "lpddr5_therm";
+	};
+
+	sys_therm1: channel@14d {
+		reg = <ADC5_GEN3_AMUX4_GPIO_100K_PU(1)>;
+		qcom,hw-settle-time = <200>;
+		qcom,ratiometric;
+		label = "usb_charger_left_therm";
+	};
+
+	sys_therm2: channel@144 {
+		reg = <ADC5_GEN3_AMUX1_THM_100K_PU(1)>;
+		qcom,hw-settle-time = <200>;
+		qcom,ratiometric;
+		label = "vph_pwr_therm";
+	};
+
+	sys_therm3: channel@145 {
+		reg = <ADC5_GEN3_AMUX2_THM_100K_PU(1)>;
+		qcom,hw-settle-time = <200>;
+		qcom,ratiometric;
+		label = "usb_charger_right_therm";
+	};
+
+	sys_therm4: channel@146 {
+		reg = <ADC5_GEN3_AMUX3_THM_100K_PU(1)>;
+		qcom,hw-settle-time = <200>;
+		qcom,ratiometric;
+		label = "ssd_conn_therm";
+	};
+
+	sys_therm5: channel@147 {
+		reg = <ADC5_GEN3_AMUX4_THM_100K_PU(1)>;
+		qcom,hw-settle-time = <200>;
+		qcom,ratiometric;
+		label = "sys_therm5";
+	};
+
+	sys_therm6: channel@148 {
+		reg = <ADC5_GEN3_AMUX5_THM_100K_PU(1)>;
+		qcom,hw-settle-time = <200>;
+		qcom,ratiometric;
+		label = "keyboard_therm";
+	};
+};
+
 &qupv3_0 {
 	status = "okay";
 };
@@ -1071,6 +1146,7 @@ &smb2360_1_eusb2_repeater {
 
 &tlmm {
 	gpio-reserved-ranges = <44 4>,  /* SPI11 (TPM) */
+			       <65 1>,  /* EC Reset, accessible but yields system unusable */
 			       <76 4>,  /* SPI19 (TZ Protected) */
 			       <238 1>; /* UFS Reset */
 
@@ -1081,6 +1157,12 @@ cam_indicator_en: cam-indicator-en-state {
 		bias-disable;
 	};
 
+	ec_int_n_default: ec-int-n-state {
+		pins = "gpio66";
+		function = "gpio";
+		bias-disable;
+	};
+
 	edp_bl_en: edp-bl-en-state {
 		pins = "gpio74";
 		function = "gpio";

-- 
2.54.0

Re: [PATCH v4 0/3] Introduce EC driver for Snapdragon X1E based Dell XPS 13 9345

[Jishnu Prakash]

On 8/9/2026 7:02 PM, Aleksandrs Vinarskis wrote:
> This series adds Embedded Controller (EC) driver for Dell XPS 13 9345.
> While EC appears to control most of device's peripherals, particular
> driver addresses power and thermal managment issues. Key operational
> principle involves initial thermistor constants configuration followed
> by a periodic reporting of these onboard thermistor values from across
> the motherboard to the EC. The latter then handles fan ramp-up/
> ramp-down internally. Suspend/Resume must be likewise propagated to EC
> for power management.
> 
> The driver was developed primarily by analyzing ACPI DSDT's _DSM and
> i2c dumps of communication between SoC and EC during various stages of
> operation (bootup, suspend, resume).
> 
> With EC driver in place, the following issues are addressed:
> 1. Fans were not properly cooling the laptop, would kick in late and
>    spin lazily, resulting in heavy throttling. With EC driver fans
>    start sooner and hit high RPM under heavy load.
> 2. Fans were not stopping once SoC temperature dropped, they would keep
>    slowly spinning irrespective of suspend and/or closed lid until the
>    next powercycle. With EC driver shortly after SoC temperature drops,
>    thermistors temperature drops, and fans ramp-down.
> 3. Keyboard and touch row backlight were not turning off during
>    suspend - only lid close would power off the touch row. With EC
>    driver behavior matches that of Windows, suspending device with lid
>    open powers off the peripherals.
> 
> As thermistor readout depends on pmic's ADCs, this series introduces
> EC driver and its schema, adds missing ADC to hamoa-pmics, and finally
> adds thermistor and EC nodes to x1e80100-dell-xps13-9345.dts.
> 
> Additional findings:
> - Max fan speed depends on Dell's power mode settings, configurable in
>   BIOS or using Windows app (relies on ACPI-WMI). It appears best
>   cooling performance is achieved under 'Ultra Performance' profile.
> - When the said power mode is changed using Windows app, EC IRQ is
>   triggered. Windows performs what appears to be thermistor contants
>   readout, though its not obvious what it is used for.
> - Given similarities between Dell XPS 13 series (codename 'tributo')
>   and Snapdragon-based Latitude, Inspiron ('thena'), including matching
>   EC address and response to suspend/resume command the EC driver can
>   be likely used for both, though in-depth testing on 'thena' is
>   required.
> 

Hi Alex,

> This series depends on QCOM SPMI PMIC5 Gen3 ADC [1], which was added to
> `linux-next` for v7.1, but must be picked if this series to be backported.
> 
> [1] https://lore.kernel.org/all/20260209105438.596339-1-jishnu.prakash@oss.qualcomm.com/
> 

Just a minor point - this link points to V11 of the patch series, but please note
V10 was the version of the series actually picked in the kernel. The difference between
V10 and V11 is minimal though.

Thanks,
Jishnu

> Signed-off-by: Aleksandrs Vinarskis <alex@vinarskis.com>
> ---
> Changes in v4:

Re: [PATCH v4 3/3] arm64: dts: qcom: x1e80100-dell-xps13-9345: introduce EC

[Konrad Dybcio]

On 8/9/26 3:32 PM, Aleksandrs Vinarskis wrote:
> Describe embedded controller, its interrupt and required thermal zones.
> Add EC's reset GPIO to reserved range, as triggering it during device
> operation leads to unrecoverable and unusable state.
> 
> Signed-off-by: Aleksandrs Vinarskis <alex@vinarskis.com>
> ---

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>

Konrad

Re: [PATCH v4 2/3] platform: arm64: dell-xps-ec: new driver

[Ilpo Järvinen]

On Sun, 9 Aug 2026, Aleksandrs Vinarskis wrote:

> Introduce EC driver for Dell XPS 13 9345 (codename 'tributo') which may
> partially of fully compatible with Snapdragon-based Dell Latitude,
> Inspiron ('thena'). Primary function of this driver is unblock EC's
> thermal management, specifically to provide it with necessary
> information to control device fans, peripherals power.
> 
> The driver was developed primarily by analyzing ACPI DSDT's _DSM and
> i2c dumps of communication between SoC and EC. Changes to Windows
> driver's behavior include increasing temperature feed loop from ~50ms
> to 100ms here.
> 
> While Xps's EC is rather complex and controls practically all device
> peripherals including touch row's brightness and special keys such as
> mic mute, these do not go over this particular i2c interface.
> 
> Not yet implemented features:
> - On lid-close IRQ event is registered. Windows performs what to
>   appears to be thermistor constants readout, though its not obvious
>   what it used for.
> - According to ACPI's _DSM there is a method to readout fans' RPM.
> - Initial thermistor constants were sniffed from Windows, these can be
>   likely fine tuned for better cooling performance.
> - There is additional temperature reading that Windows sents to EC but
>   more rare than others, likely SoC T_j / TZ98 or TZ4. This is the only
>   thermal zone who's reading can exceed 115C without triggering thermal
>   shutdown.
> - Given similarities between 'tributo' and 'thena' platforms, including
>   EC i2c address, driver can be potentially extended to support both.
> 
> Signed-off-by: Aleksandrs Vinarskis <alex@vinarskis.com>
> ---
>  MAINTAINERS                          |   1 +
>  drivers/platform/arm64/Kconfig       |  12 ++
>  drivers/platform/arm64/Makefile      |   1 +
>  drivers/platform/arm64/dell-xps-ec.c | 299 +++++++++++++++++++++++++++++++++++
>  4 files changed, 313 insertions(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 9b238f14f0be..ad5231846493 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -7352,6 +7352,7 @@ DELL XPS EMBEDDED CONTROLLER DRIVER
>  M:	Aleksandrs Vinarskis <alex@vinarskis.com>
>  S:	Maintained
>  F:	Documentation/devicetree/bindings/embedded-controller/dell,xps13-9345-ec.yaml
> +F:	drivers/platform/arm64/dell-xps-ec.c
>  
>  DELTA AHE-50DC FAN CONTROL MODULE DRIVER
>  M:	Zev Weiss <zev@bewilderbeest.net>
> diff --git a/drivers/platform/arm64/Kconfig b/drivers/platform/arm64/Kconfig
> index e32e01b2a9bd..29416f8d7232 100644
> --- a/drivers/platform/arm64/Kconfig
> +++ b/drivers/platform/arm64/Kconfig
> @@ -33,6 +33,18 @@ config EC_ACER_ASPIRE1
>  	  laptop where this information is not properly exposed via the
>  	  standard ACPI devices.
>  
> +config EC_DELL_XPS
> +	tristate "Dell XPS 9345 Embedded Controller driver"
> +	depends on ARCH_QCOM || COMPILE_TEST
> +	depends on I2C
> +	depends on IIO
> +	help
> +	  Driver for the Embedded Controller in the Qualcomm Snapdragon-based
> +	  Dell XPS 13 9345, which handles thermal management and fan speed
> +	  control.
> +
> +	  Say M or Y here to include this support.
> +
>  config EC_HUAWEI_GAOKUN
>  	tristate "Huawei Matebook E Go Embedded Controller driver"
>  	depends on ARCH_QCOM || COMPILE_TEST
> diff --git a/drivers/platform/arm64/Makefile b/drivers/platform/arm64/Makefile
> index 7681be4a46e9..669dc9e79afb 100644
> --- a/drivers/platform/arm64/Makefile
> +++ b/drivers/platform/arm64/Makefile
> @@ -6,6 +6,7 @@
>  #
>  
>  obj-$(CONFIG_EC_ACER_ASPIRE1)	+= acer-aspire1-ec.o
> +obj-$(CONFIG_EC_DELL_XPS)	+= dell-xps-ec.o
>  obj-$(CONFIG_EC_HUAWEI_GAOKUN)	+= huawei-gaokun-ec.o
>  obj-$(CONFIG_EC_LENOVO_YOGA_C630) += lenovo-yoga-c630.o
>  obj-$(CONFIG_EC_LENOVO_THINKPAD_T14S) += lenovo-thinkpad-t14s.o
> diff --git a/drivers/platform/arm64/dell-xps-ec.c b/drivers/platform/arm64/dell-xps-ec.c
> new file mode 100644
> index 000000000000..695a7d01acd6
> --- /dev/null
> +++ b/drivers/platform/arm64/dell-xps-ec.c
> @@ -0,0 +1,299 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2026, Aleksandrs Vinarskis <alex@vinarskis.com>
> + */
> +
> +#include <linux/array_size.h>
> +#include <linux/dev_printk.h>
> +#include <linux/device.h>
> +#include <linux/devm-helpers.h>
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/iio/consumer.h>
> +#include <linux/interrupt.h>
> +#include <linux/jiffies.h>
> +#include <linux/module.h>
> +#include <linux/overflow.h>
> +#include <linux/pm.h>
> +#include <linux/types.h>
> +#include <linux/unaligned.h>
> +#include <linux/workqueue.h>
> +
> +#define DELL_XPS_EC_SUSPEND_CMD		0xb9
> +#define DELL_XPS_EC_SUSPEND_MSG_LEN	64
> +
> +#define DELL_XPS_EC_TEMP_CMD0		0xfb
> +#define DELL_XPS_EC_TEMP_CMD1		0x20
> +#define DELL_XPS_EC_TEMP_CMD3		0x02
> +#define DELL_XPS_EC_TEMP_MSG_LEN	6
> +#define DELL_XPS_EC_TEMP_POLL_JIFFIES	msecs_to_jiffies(100)
> +
> +/*
> + * Mapping between IIO channel name (as per schematics) and EC command byte
> + */
> +struct dell_xps_ec_therm {
> +	const char *name;
> +	u8 cmd;
> +};
> +
> +struct dell_xps_ec_data {
> +	const struct dell_xps_ec_therm *therms;
> +	unsigned int num_therms;
> +	const u8 *profile;
> +	size_t profile_len;
> +};
> +
> +/*
> + * Format:
> + * - header/unknown (2 bytes)
> + * - per-thermistor entries (3 bytes): thermistor_id, param1, param2
> + */
> +static const u8 dell_xps13_9345_thermistor_profile[] = {
> +	0xff, 0x54,
> +	0x01, 0x00, 0x2b,	/* sys_therm0 */
> +	0x02, 0x44, 0x2a,	/* sys_therm1 */
> +	0x03, 0x44, 0x2b,	/* sys_therm2 */
> +	0x04, 0x44, 0x28,	/* sys_therm3 */
> +	0x05, 0x55, 0x2a,	/* sys_therm4 */
> +	0x06, 0x44, 0x26,	/* sys_therm5 */
> +	0x07, 0x44, 0x2b,	/* sys_therm6 */
> +};
> +
> +static const struct dell_xps_ec_therm dell_xps13_9345_therms[] = {
> +	/* TODO: 0x01 is sent only occasionally, likely TZ98 or TZ4 */
> +	{ "sys_therm0", 0x02 },
> +	{ "sys_therm1", 0x03 },
> +	{ "sys_therm2", 0x04 },
> +	{ "sys_therm3", 0x05 },
> +	{ "sys_therm4", 0x06 },
> +	{ "sys_therm5", 0x07 },
> +	{ "sys_therm6", 0x08 },

I suppose it's intentional that thermistor_id and the values here do not 
match?

Take the comment with a grain of salt as this was mentioned by sashiko and 
I don't really believe it when it comes to assuming things like this, so 
no action is needed if they're correct as is.

> +};
> +
> +static const struct dell_xps_ec_data dell_xps13_9345_data = {
> +	.therms = dell_xps13_9345_therms,
> +	.num_therms = ARRAY_SIZE(dell_xps13_9345_therms),
> +	.profile = dell_xps13_9345_thermistor_profile,
> +	.profile_len = sizeof(dell_xps13_9345_thermistor_profile),
> +};
> +
> +struct dell_xps_ec {
> +	struct device *dev;
> +	struct i2c_client *client;
> +	const struct dell_xps_ec_data *data;
> +	struct delayed_work temp_work;
> +	unsigned int num_therms;
> +	struct iio_channel *therm_channels[] __counted_by(num_therms);
> +};
> +
> +static int dell_xps_ec_suspend_cmd(struct dell_xps_ec *ec, bool suspend)
> +{
> +	u8 buf[DELL_XPS_EC_SUSPEND_MSG_LEN] = {};
> +	int ret;
> +
> +	buf[0] = DELL_XPS_EC_SUSPEND_CMD;
> +	buf[1] = suspend ? 0x01 : 0x00;
> +	/* bytes 2..63 remain zero */
> +
> +	ret = i2c_master_send(ec->client, buf, sizeof(buf));
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int dell_xps_ec_send_temp(struct dell_xps_ec *ec, u8 cmd_byte,
> +				 int milli_celsius)
> +{
> +	u8 buf[DELL_XPS_EC_TEMP_MSG_LEN];
> +	u16 deci_celsius;
> +	int ret;
> +
> +	/* Convert millicelsius to decicelsius */
> +	deci_celsius = milli_celsius / 100;

Please use a define from units.h and remove the comment.

> +	buf[0] = DELL_XPS_EC_TEMP_CMD0;
> +	buf[1] = DELL_XPS_EC_TEMP_CMD1;
> +	buf[2] = cmd_byte;
> +	buf[3] = DELL_XPS_EC_TEMP_CMD3;
> +	put_unaligned_le16(deci_celsius, &buf[4]);
> +
> +	ret = i2c_master_send(ec->client, buf, sizeof(buf));
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static void dell_xps_ec_temp_work_fn(struct work_struct *work)
> +{
> +	struct dell_xps_ec *ec = container_of(work, struct dell_xps_ec,
> +					      temp_work.work);

Add include for container_of().

> +	const struct dell_xps_ec_therm *therms = ec->data->therms;
> +	int val, ret;
> +	unsigned int i;
> +
> +	for (i = 0; i < ec->num_therms; i++) {
> +		if (!ec->therm_channels[i])
> +			continue;
> +
> +		ret = iio_read_channel_processed(ec->therm_channels[i], &val);
> +		if (ret < 0) {
> +			dev_err_ratelimited(ec->dev,
> +					    "Failed to read thermistor %s: %d\n",
> +					    therms[i].name, ret);
> +			continue;
> +		}
> +
> +		ret = dell_xps_ec_send_temp(ec, therms[i].cmd, val);
> +		if (ret < 0) {
> +			dev_err_ratelimited(ec->dev,
> +					    "Failed to send temp for %s: %d\n",
> +					    therms[i].name, ret);
> +		}
> +	}
> +
> +	schedule_delayed_work(&ec->temp_work, DELL_XPS_EC_TEMP_POLL_JIFFIES);
> +}
> +
> +static irqreturn_t dell_xps_ec_irq_handler(int irq, void *data)
> +{
> +	struct dell_xps_ec *ec = data;
> +
> +	/*
> +	 * TODO: IRQ is fired on lid-close. Follow Windows example to read out
> +	 *       the thermistor thresholds and potentially fan speeds.
> +	 */
> +	dev_info_ratelimited(ec->dev, "IRQ triggered! (irq=%d)\n", irq);

How is this print beneficial to a normal user? Debug level would be more 
appropriate for something like this if you need to print it at all, there 
are other ways to track function calls besides printing.

> +	return IRQ_HANDLED;
> +}
> +
> +static int dell_xps_ec_probe(struct i2c_client *client)
> +{
> +	const struct dell_xps_ec_data *data;
> +	struct device *dev = &client->dev;
> +	struct dell_xps_ec *ec;
> +	unsigned int i;
> +	int ret;
> +
> +	data = i2c_get_match_data(client);
> +	if (!data)
> +		return dev_err_probe(dev, -ENODEV, "No match data\n");
> +
> +	ec = devm_kzalloc(dev, struct_size(ec, therm_channels, data->num_therms),
> +			  GFP_KERNEL);
> +	if (!ec)
> +		return -ENOMEM;
> +
> +	ec->dev = dev;
> +	ec->client = client;
> +	ec->data = data;
> +	ec->num_therms = data->num_therms;
> +	i2c_set_clientdata(client, ec);
> +
> +	/* Set default thermistor profile */
> +	ret = i2c_master_send(client, data->profile, data->profile_len);
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "Failed to set thermistor profile\n");
> +
> +	/* Get IIO channels for thermistors */
> +	for (i = 0; i < ec->num_therms; i++) {
> +		ec->therm_channels[i] =
> +			devm_iio_channel_get(dev, data->therms[i].name);
> +		if (IS_ERR(ec->therm_channels[i])) {
> +			ret = PTR_ERR(ec->therm_channels[i]);
> +			ec->therm_channels[i] = NULL;
> +			if (ret == -EPROBE_DEFER)
> +				return ret;
> +			dev_warn(dev, "Thermistor %s not available: %d\n",
> +				 data->therms[i].name, ret);
> +		}
> +	}
> +
> +	/* Start periodic temperature reporting */
> +	ret = devm_delayed_work_autocancel(dev, &ec->temp_work,
> +					   dell_xps_ec_temp_work_fn);
> +	if (ret)
> +		return ret;
> +	schedule_delayed_work(&ec->temp_work, DELL_XPS_EC_TEMP_POLL_JIFFIES);
> +	dev_dbg(dev, "Started periodic temperature reporting to EC every %d ms\n",
> +		jiffies_to_msecs(DELL_XPS_EC_TEMP_POLL_JIFFIES));
> +
> +	/* Request IRQ for EC events */
> +	ret = devm_request_threaded_irq(dev, client->irq, NULL,
> +					dell_xps_ec_irq_handler,
> +					IRQF_ONESHOT, dev_name(dev), ec);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to request IRQ\n");
> +
> +	return 0;
> +}
> +
> +/*
> + * Notify EC of suspend
> + *
> + * This will:
> + * - Cut power to display/trackpad/keyboard/touchrow, wake-up source still works
> + */
> +static int dell_xps_ec_suspend(struct device *dev)
> +{
> +	struct dell_xps_ec *ec = dev_get_drvdata(dev);
> +
> +	cancel_delayed_work_sync(&ec->temp_work);
> +
> +	return dell_xps_ec_suspend_cmd(ec, true);
> +}
> +
> +/*
> + * Notify EC of resume
> + *
> + * This will undo the suspend actions
> + * Without the resume signal, device would wake up but be forced back into
> + * suspend by EC within seconds

Please terminate sentences in comments properly with a stop (.).

> + */
> +static int dell_xps_ec_resume(struct device *dev)
> +{
> +	struct dell_xps_ec *ec = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = dell_xps_ec_suspend_cmd(ec, false);
> +	if (ret)
> +		return ret;
> +
> +	schedule_delayed_work(&ec->temp_work, DELL_XPS_EC_TEMP_POLL_JIFFIES);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id dell_xps_ec_of_match[] = {
> +	{ .compatible = "dell,xps13-9345-ec", .data = &dell_xps13_9345_data },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, dell_xps_ec_of_match);
> +
> +static const struct i2c_device_id dell_xps_ec_i2c_id[] = {
> +	{ "dell-xps-ec", (kernel_ulong_t)&dell_xps13_9345_data },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(i2c, dell_xps_ec_i2c_id);
> +
> +static const struct dev_pm_ops dell_xps_ec_pm_ops = {
> +	SYSTEM_SLEEP_PM_OPS(dell_xps_ec_suspend, dell_xps_ec_resume)
> +};
> +
> +static struct i2c_driver dell_xps_ec_driver = {
> +	.driver = {
> +		.name = "dell-xps-ec",
> +		.of_match_table = dell_xps_ec_of_match,
> +		.pm = &dell_xps_ec_pm_ops,
> +	},
> +	.probe = dell_xps_ec_probe,
> +	.id_table = dell_xps_ec_i2c_id,
> +};
> +module_i2c_driver(dell_xps_ec_driver);
> +
> +MODULE_AUTHOR("Aleksandrs Vinarskis <alex@vinarskis.com>");
> +MODULE_DESCRIPTION("Dell XPS 13 9345 Embedded Controller");
> +MODULE_LICENSE("GPL");
> +MODULE_IMPORT_NS("IIO_CONSUMER");
> 
> 

-- 
 i.

Re: [PATCH v4 2/3] platform: arm64: dell-xps-ec: new driver

[Ilpo Järvinen]

On Sun, 9 Aug 2026, Aleksandrs Vinarskis wrote:

> Introduce EC driver for Dell XPS 13 9345 (codename 'tributo') which may
> partially of fully compatible with Snapdragon-based Dell Latitude,
> Inspiron ('thena'). Primary function of this driver is unblock EC's
> thermal management, specifically to provide it with necessary
> information to control device fans, peripherals power.
> 
> The driver was developed primarily by analyzing ACPI DSDT's _DSM and
> i2c dumps of communication between SoC and EC. Changes to Windows
> driver's behavior include increasing temperature feed loop from ~50ms
> to 100ms here.
> 
> While Xps's EC is rather complex and controls practically all device
> peripherals including touch row's brightness and special keys such as
> mic mute, these do not go over this particular i2c interface.
> 
> Not yet implemented features:
> - On lid-close IRQ event is registered. Windows performs what to
>   appears to be thermistor constants readout, though its not obvious
>   what it used for.
> - According to ACPI's _DSM there is a method to readout fans' RPM.
> - Initial thermistor constants were sniffed from Windows, these can be
>   likely fine tuned for better cooling performance.
> - There is additional temperature reading that Windows sents to EC but
>   more rare than others, likely SoC T_j / TZ98 or TZ4. This is the only
>   thermal zone who's reading can exceed 115C without triggering thermal
>   shutdown.
> - Given similarities between 'tributo' and 'thena' platforms, including
>   EC i2c address, driver can be potentially extended to support both.
> 
> Signed-off-by: Aleksandrs Vinarskis <alex@vinarskis.com>
> ---
>  MAINTAINERS                          |   1 +
>  drivers/platform/arm64/Kconfig       |  12 ++
>  drivers/platform/arm64/Makefile      |   1 +
>  drivers/platform/arm64/dell-xps-ec.c | 299 +++++++++++++++++++++++++++++++++++
>  4 files changed, 313 insertions(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 9b238f14f0be..ad5231846493 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -7352,6 +7352,7 @@ DELL XPS EMBEDDED CONTROLLER DRIVER
>  M:	Aleksandrs Vinarskis <alex@vinarskis.com>
>  S:	Maintained
>  F:	Documentation/devicetree/bindings/embedded-controller/dell,xps13-9345-ec.yaml
> +F:	drivers/platform/arm64/dell-xps-ec.c
>  
>  DELTA AHE-50DC FAN CONTROL MODULE DRIVER
>  M:	Zev Weiss <zev@bewilderbeest.net>
> diff --git a/drivers/platform/arm64/Kconfig b/drivers/platform/arm64/Kconfig
> index e32e01b2a9bd..29416f8d7232 100644
> --- a/drivers/platform/arm64/Kconfig
> +++ b/drivers/platform/arm64/Kconfig
> @@ -33,6 +33,18 @@ config EC_ACER_ASPIRE1
>  	  laptop where this information is not properly exposed via the
>  	  standard ACPI devices.
>  
> +config EC_DELL_XPS
> +	tristate "Dell XPS 9345 Embedded Controller driver"
> +	depends on ARCH_QCOM || COMPILE_TEST
> +	depends on I2C
> +	depends on IIO
> +	help
> +	  Driver for the Embedded Controller in the Qualcomm Snapdragon-based
> +	  Dell XPS 13 9345, which handles thermal management and fan speed
> +	  control.
> +
> +	  Say M or Y here to include this support.
> +
>  config EC_HUAWEI_GAOKUN
>  	tristate "Huawei Matebook E Go Embedded Controller driver"
>  	depends on ARCH_QCOM || COMPILE_TEST
> diff --git a/drivers/platform/arm64/Makefile b/drivers/platform/arm64/Makefile
> index 7681be4a46e9..669dc9e79afb 100644
> --- a/drivers/platform/arm64/Makefile
> +++ b/drivers/platform/arm64/Makefile
> @@ -6,6 +6,7 @@
>  #
>  
>  obj-$(CONFIG_EC_ACER_ASPIRE1)	+= acer-aspire1-ec.o
> +obj-$(CONFIG_EC_DELL_XPS)	+= dell-xps-ec.o
>  obj-$(CONFIG_EC_HUAWEI_GAOKUN)	+= huawei-gaokun-ec.o
>  obj-$(CONFIG_EC_LENOVO_YOGA_C630) += lenovo-yoga-c630.o
>  obj-$(CONFIG_EC_LENOVO_THINKPAD_T14S) += lenovo-thinkpad-t14s.o
> diff --git a/drivers/platform/arm64/dell-xps-ec.c b/drivers/platform/arm64/dell-xps-ec.c
> new file mode 100644
> index 000000000000..695a7d01acd6
> --- /dev/null
> +++ b/drivers/platform/arm64/dell-xps-ec.c
> @@ -0,0 +1,299 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2026, Aleksandrs Vinarskis <alex@vinarskis.com>
> + */
> +
> +#include <linux/array_size.h>
> +#include <linux/dev_printk.h>
> +#include <linux/device.h>
> +#include <linux/devm-helpers.h>
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/iio/consumer.h>
> +#include <linux/interrupt.h>
> +#include <linux/jiffies.h>
> +#include <linux/module.h>
> +#include <linux/overflow.h>
> +#include <linux/pm.h>
> +#include <linux/types.h>
> +#include <linux/unaligned.h>
> +#include <linux/workqueue.h>
> +
> +#define DELL_XPS_EC_SUSPEND_CMD		0xb9
> +#define DELL_XPS_EC_SUSPEND_MSG_LEN	64
> +
> +#define DELL_XPS_EC_TEMP_CMD0		0xfb
> +#define DELL_XPS_EC_TEMP_CMD1		0x20
> +#define DELL_XPS_EC_TEMP_CMD3		0x02
> +#define DELL_XPS_EC_TEMP_MSG_LEN	6
> +#define DELL_XPS_EC_TEMP_POLL_JIFFIES	msecs_to_jiffies(100)
> +
> +/*
> + * Mapping between IIO channel name (as per schematics) and EC command byte
> + */
> +struct dell_xps_ec_therm {
> +	const char *name;
> +	u8 cmd;
> +};
> +
> +struct dell_xps_ec_data {
> +	const struct dell_xps_ec_therm *therms;
> +	unsigned int num_therms;
> +	const u8 *profile;
> +	size_t profile_len;
> +};
> +
> +/*
> + * Format:
> + * - header/unknown (2 bytes)
> + * - per-thermistor entries (3 bytes): thermistor_id, param1, param2
> + */
> +static const u8 dell_xps13_9345_thermistor_profile[] = {
> +	0xff, 0x54,
> +	0x01, 0x00, 0x2b,	/* sys_therm0 */
> +	0x02, 0x44, 0x2a,	/* sys_therm1 */
> +	0x03, 0x44, 0x2b,	/* sys_therm2 */
> +	0x04, 0x44, 0x28,	/* sys_therm3 */
> +	0x05, 0x55, 0x2a,	/* sys_therm4 */
> +	0x06, 0x44, 0x26,	/* sys_therm5 */
> +	0x07, 0x44, 0x2b,	/* sys_therm6 */
> +};
> +
> +static const struct dell_xps_ec_therm dell_xps13_9345_therms[] = {
> +	/* TODO: 0x01 is sent only occasionally, likely TZ98 or TZ4 */
> +	{ "sys_therm0", 0x02 },
> +	{ "sys_therm1", 0x03 },
> +	{ "sys_therm2", 0x04 },
> +	{ "sys_therm3", 0x05 },
> +	{ "sys_therm4", 0x06 },
> +	{ "sys_therm5", 0x07 },
> +	{ "sys_therm6", 0x08 },
> +};
> +
> +static const struct dell_xps_ec_data dell_xps13_9345_data = {
> +	.therms = dell_xps13_9345_therms,
> +	.num_therms = ARRAY_SIZE(dell_xps13_9345_therms),
> +	.profile = dell_xps13_9345_thermistor_profile,
> +	.profile_len = sizeof(dell_xps13_9345_thermistor_profile),
> +};
> +
> +struct dell_xps_ec {
> +	struct device *dev;
> +	struct i2c_client *client;
> +	const struct dell_xps_ec_data *data;
> +	struct delayed_work temp_work;
> +	unsigned int num_therms;
> +	struct iio_channel *therm_channels[] __counted_by(num_therms);
> +};
> +
> +static int dell_xps_ec_suspend_cmd(struct dell_xps_ec *ec, bool suspend)
> +{
> +	u8 buf[DELL_XPS_EC_SUSPEND_MSG_LEN] = {};
> +	int ret;
> +
> +	buf[0] = DELL_XPS_EC_SUSPEND_CMD;
> +	buf[1] = suspend ? 0x01 : 0x00;
> +	/* bytes 2..63 remain zero */
> +
> +	ret = i2c_master_send(ec->client, buf, sizeof(buf));
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int dell_xps_ec_send_temp(struct dell_xps_ec *ec, u8 cmd_byte,
> +				 int milli_celsius)
> +{
> +	u8 buf[DELL_XPS_EC_TEMP_MSG_LEN];
> +	u16 deci_celsius;
> +	int ret;
> +
> +	/* Convert millicelsius to decicelsius */
> +	deci_celsius = milli_celsius / 100;
> +
> +	buf[0] = DELL_XPS_EC_TEMP_CMD0;
> +	buf[1] = DELL_XPS_EC_TEMP_CMD1;
> +	buf[2] = cmd_byte;
> +	buf[3] = DELL_XPS_EC_TEMP_CMD3;
> +	put_unaligned_le16(deci_celsius, &buf[4]);
> +
> +	ret = i2c_master_send(ec->client, buf, sizeof(buf));
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static void dell_xps_ec_temp_work_fn(struct work_struct *work)
> +{
> +	struct dell_xps_ec *ec = container_of(work, struct dell_xps_ec,
> +					      temp_work.work);
> +	const struct dell_xps_ec_therm *therms = ec->data->therms;
> +	int val, ret;
> +	unsigned int i;
> +
> +	for (i = 0; i < ec->num_therms; i++) {
> +		if (!ec->therm_channels[i])
> +			continue;
> +
> +		ret = iio_read_channel_processed(ec->therm_channels[i], &val);
> +		if (ret < 0) {
> +			dev_err_ratelimited(ec->dev,
> +					    "Failed to read thermistor %s: %d\n",
> +					    therms[i].name, ret);
> +			continue;
> +		}
> +
> +		ret = dell_xps_ec_send_temp(ec, therms[i].cmd, val);
> +		if (ret < 0) {
> +			dev_err_ratelimited(ec->dev,
> +					    "Failed to send temp for %s: %d\n",
> +					    therms[i].name, ret);
> +		}
> +	}
> +
> +	schedule_delayed_work(&ec->temp_work, DELL_XPS_EC_TEMP_POLL_JIFFIES);
> +}
> +
> +static irqreturn_t dell_xps_ec_irq_handler(int irq, void *data)
> +{
> +	struct dell_xps_ec *ec = data;
> +
> +	/*
> +	 * TODO: IRQ is fired on lid-close. Follow Windows example to read out
> +	 *       the thermistor thresholds and potentially fan speeds.
> +	 */
> +	dev_info_ratelimited(ec->dev, "IRQ triggered! (irq=%d)\n", irq);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int dell_xps_ec_probe(struct i2c_client *client)
> +{
> +	const struct dell_xps_ec_data *data;
> +	struct device *dev = &client->dev;
> +	struct dell_xps_ec *ec;
> +	unsigned int i;
> +	int ret;
> +
> +	data = i2c_get_match_data(client);
> +	if (!data)
> +		return dev_err_probe(dev, -ENODEV, "No match data\n");
> +
> +	ec = devm_kzalloc(dev, struct_size(ec, therm_channels, data->num_therms),
> +			  GFP_KERNEL);
> +	if (!ec)
> +		return -ENOMEM;
> +
> +	ec->dev = dev;
> +	ec->client = client;
> +	ec->data = data;
> +	ec->num_therms = data->num_therms;
> +	i2c_set_clientdata(client, ec);
> +
> +	/* Set default thermistor profile */
> +	ret = i2c_master_send(client, data->profile, data->profile_len);
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "Failed to set thermistor profile\n");
> +
> +	/* Get IIO channels for thermistors */
> +	for (i = 0; i < ec->num_therms; i++) {
> +		ec->therm_channels[i] =
> +			devm_iio_channel_get(dev, data->therms[i].name);
> +		if (IS_ERR(ec->therm_channels[i])) {
> +			ret = PTR_ERR(ec->therm_channels[i]);
> +			ec->therm_channels[i] = NULL;
> +			if (ret == -EPROBE_DEFER)
> +				return ret;
> +			dev_warn(dev, "Thermistor %s not available: %d\n",
> +				 data->therms[i].name, ret);
> +		}
> +	}
> +
> +	/* Start periodic temperature reporting */
> +	ret = devm_delayed_work_autocancel(dev, &ec->temp_work,
> +					   dell_xps_ec_temp_work_fn);
> +	if (ret)
> +		return ret;
> +	schedule_delayed_work(&ec->temp_work, DELL_XPS_EC_TEMP_POLL_JIFFIES);
> +	dev_dbg(dev, "Started periodic temperature reporting to EC every %d ms\n",
> +		jiffies_to_msecs(DELL_XPS_EC_TEMP_POLL_JIFFIES));
> +
> +	/* Request IRQ for EC events */
> +	ret = devm_request_threaded_irq(dev, client->irq, NULL,
> +					dell_xps_ec_irq_handler,
> +					IRQF_ONESHOT, dev_name(dev), ec);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to request IRQ\n");
> +
> +	return 0;
> +}
> +
> +/*
> + * Notify EC of suspend
> + *
> + * This will:
> + * - Cut power to display/trackpad/keyboard/touchrow, wake-up source still works
> + */
> +static int dell_xps_ec_suspend(struct device *dev)
> +{
> +	struct dell_xps_ec *ec = dev_get_drvdata(dev);
> +
> +	cancel_delayed_work_sync(&ec->temp_work);
> +
> +	return dell_xps_ec_suspend_cmd(ec, true);

Sashiko mentions that if suspend fails, the work remains cancelled.

-- 
 i.

> +}
> +
> +/*
> + * Notify EC of resume
> + *
> + * This will undo the suspend actions
> + * Without the resume signal, device would wake up but be forced back into
> + * suspend by EC within seconds
> + */
> +static int dell_xps_ec_resume(struct device *dev)
> +{
> +	struct dell_xps_ec *ec = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = dell_xps_ec_suspend_cmd(ec, false);
> +	if (ret)
> +		return ret;
> +
> +	schedule_delayed_work(&ec->temp_work, DELL_XPS_EC_TEMP_POLL_JIFFIES);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id dell_xps_ec_of_match[] = {
> +	{ .compatible = "dell,xps13-9345-ec", .data = &dell_xps13_9345_data },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, dell_xps_ec_of_match);
> +
> +static const struct i2c_device_id dell_xps_ec_i2c_id[] = {
> +	{ "dell-xps-ec", (kernel_ulong_t)&dell_xps13_9345_data },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(i2c, dell_xps_ec_i2c_id);
> +
> +static const struct dev_pm_ops dell_xps_ec_pm_ops = {
> +	SYSTEM_SLEEP_PM_OPS(dell_xps_ec_suspend, dell_xps_ec_resume)
> +};
> +
> +static struct i2c_driver dell_xps_ec_driver = {
> +	.driver = {
> +		.name = "dell-xps-ec",
> +		.of_match_table = dell_xps_ec_of_match,
> +		.pm = &dell_xps_ec_pm_ops,
> +	},
> +	.probe = dell_xps_ec_probe,
> +	.id_table = dell_xps_ec_i2c_id,
> +};
> +module_i2c_driver(dell_xps_ec_driver);
> +
> +MODULE_AUTHOR("Aleksandrs Vinarskis <alex@vinarskis.com>");
> +MODULE_DESCRIPTION("Dell XPS 13 9345 Embedded Controller");
> +MODULE_LICENSE("GPL");
> +MODULE_IMPORT_NS("IIO_CONSUMER");
> 
>