[RFC PATCH v2 0/2] Monitor Yoga Slim 7x EC sensors without taking over cooling

[RFC PATCH v2 0/2] Monitor Yoga Slim 7x EC sensors without taking over cooling

[Birk Skyum]

The Yoga Slim 7x firmware tested here (EC 0.99.0, BIOS NHCN62WW) returns
00 00 00 to command 0x42. The upstream driver correctly rejects that
malformed thermal capability response. Its legacy fan RPM query (0x22,
fan ID 1) and thermistor query (0x29) work, and the firmware ramps the fan
automatically under CPU load.

This series adds a Lenovo-specific, read-only path to the existing driver
and KUnit tests using a simulated I2C adapter. It does not replace the
strict reference-board response validation, guess a writable fan count,
or include calibration, LUT programming or temperature reporting.

Changes in v2:
- Move the platform-driver documentation from Documentation/hwmon/ to
  Documentation/admin-guide/laptops/, following Guenter's review [3].
- Update the documentation index and MAINTAINERS path accordingly.

Driver and test code are unchanged from v1 [4]. The hardware and KUnit
results below are from that version; no new hardware test is claimed.

This builds on Daniel J Blueman's pending binding and board patches [1].
They remain separate prerequisites, with Daniel's authorship unchanged.
The sensor transactions are documented in the public Yoga DSDT and Maya
Matuszczyk's protocol notes; Anvesh Jain P's pending fan-profile series
also implements the RPM query [2].

Testing on the Yoga with the EC node enabled and its existing 7.2 kernel:
- W=1 external-module build.
- Three bind/read/unload cycles; read-only fan1_input and temp1_input.
- Bounded CPU load: fan rose from 0 to approximately 2800 RPM, with a
  maximum SoC reading of 55.4 C. Original profile 0x15 was unchanged.
- Previous monitor restored after testing; boot files unchanged.

On the stated mainline base, an arm64 KUnit kernel booted in QEMU passes
all seven tests. These cover sensor decoding, error handling, compatible
selection, probe, read-only attributes and no-write PM/remove callbacks.
The QEMU results validate code paths, not Yoga suspend behavior.

Two design questions for this RFC:
- Is this read-only match-data path the preferred way to accommodate
  the Lenovo firmware alongside the reference-board work?
- Should the pending Lenovo binding omit the qcom,hamoa-crd-ec fallback,
  given that this firmware cannot satisfy the reference driver's probe?

EC standby notifications and desktop power-profile integration are not
implemented or claimed by this series. Those need separate validation.

[1] https://lore.kernel.org/all/20260526112409.66325-1-daniel@quora.org/
[2] https://lkml.iu.edu/hypermail/linux/kernel/2607.3/08806.html
[3] https://lists.openwall.net/linux-kernel/2026/09/08/290
[4] https://lists.openwall.net/linux-kernel/2026/09/08/96

Birk Skyum (2):
  platform: arm64: qcom-hamoa-ec: monitor Slim 7x legacy sensors
  platform: arm64: qcom-hamoa-ec: test sensor and variant handling

 Documentation/admin-guide/laptops/index.rst   |   1 +
 Documentation/admin-guide/laptops/qcom-ec.rst |  40 +++
 MAINTAINERS                                   |   2 +
 drivers/platform/arm64/Kconfig                |  16 +-
 drivers/platform/arm64/qcom-hamoa-ec-test.c   | 294 ++++++++++++++++++
 drivers/platform/arm64/qcom-hamoa-ec.c        | 157 +++++++++-
 6 files changed, 505 insertions(+), 5 deletions(-)
 create mode 100644 Documentation/admin-guide/laptops/qcom-ec.rst
 create mode 100644 drivers/platform/arm64/qcom-hamoa-ec-test.c


base-commit: 28924df2a08f440c73991b83028032c901de2ae4
-- 
2.53.0

[RFC PATCH v2 1/2] platform: arm64: qcom-hamoa-ec: monitor Slim 7x legacy sensors

[Birk Skyum]

The Yoga Slim 7x EC returns an all-zero response to the reference-board
thermal capability command. Probe fails even though its legacy RPM and
thermistor queries work and firmware controls the fan automatically.

Select a read-only path for the Lenovo compatible. Expose its first RPM
channel and thermistor through hwmon, validating the transfer length and
RPM payload count and treating the thermistor's 0xff sentinel as ENODATA.
Do not enable SCI, register manual cooling controls or send standby
commands on this path. Keep the reference-board behavior and strict
capability validation unchanged.

The transactions are documented by the Yoga's FC22 and FC29/TZ39 DSDT
methods and Maya Matuszczyk's EC protocol notes. Anvesh Jain P's pending
fan-profile series also documents the RPM query. This change does not
include its calibration, LUT programming or temperature reporting.

Link: https://github.com/aarch64-laptops/build/blob/2e58842f5fa2f87771c2df017ae4d8c65225ef10/misc/lenovo-yoga-slim-7x/acpi/dsdt.dsl
Link: https://lkml.iu.edu/hypermail/linux/kernel/2607.3/08806.html
Signed-off-by: Birk Skyum <birk.skyum@pm.me>
---
Changes in v2:
- Move the platform-driver documentation to the laptop-driver guide and
  update its index and MAINTAINERS entry, following Guenter's review.
- No driver code changes.

 Documentation/admin-guide/laptops/index.rst   |   1 +
 Documentation/admin-guide/laptops/qcom-ec.rst |  40 +++++
 MAINTAINERS                                   |   1 +
 drivers/platform/arm64/Kconfig                |   4 +-
 drivers/platform/arm64/qcom-hamoa-ec.c        | 153 +++++++++++++++++-
 5 files changed, 194 insertions(+), 5 deletions(-)
 create mode 100644 Documentation/admin-guide/laptops/qcom-ec.rst

diff --git a/Documentation/admin-guide/laptops/index.rst b/Documentation/admin-guide/laptops/index.rst
index c0b911d05..44c9c7c08 100644
--- a/Documentation/admin-guide/laptops/index.rst
+++ b/Documentation/admin-guide/laptops/index.rst
@@ -11,6 +11,7 @@ Laptop Drivers
    asus-laptop
    disk-shock-protection
    lg-laptop
+   qcom-ec
    samsung-galaxybook
    sony-laptop
    sonypi
diff --git a/Documentation/admin-guide/laptops/qcom-ec.rst b/Documentation/admin-guide/laptops/qcom-ec.rst
new file mode 100644
index 000000000..11f9f2347
--- /dev/null
+++ b/Documentation/admin-guide/laptops/qcom-ec.rst
@@ -0,0 +1,40 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+Kernel driver qcom-hamoa-ec
+==========================
+
+Supported systems:
+
+  * Lenovo Yoga Slim 7x (14Q8X9)
+
+    Prefix: 'qcom_ec'
+
+    I2C address: 0x76, instantiated from the device tree. No scanning.
+
+Description
+-----------
+
+The Yoga Slim 7x embedded controller provides a fan speed channel and a
+thermistor through a legacy interface. It does not provide the thermal
+capability response used by the Qualcomm reference-board interface.
+
+On this system the driver only reads sensors. Cooling remains under firmware
+control, including when the driver is unloaded. The driver does not change
+fan curves, fan profiles, PWM settings, SCI events or EC standby state.
+The exposed RPM channel does not establish the number of physical fans.
+
+The hwmon interface is selected by the ``lenovo,yoga-slim7x-ec`` compatible.
+It is not exposed on Qualcomm reference boards by this driver.
+
+Sysfs attributes
+----------------
+
+All attributes below are read-only.
+
+=============== ======================================================
+fan1_input      Fan speed in RPM. Zero is valid when the fan is stopped.
+temp1_input     EC thermistor temperature in millidegrees Celsius.
+=============== ======================================================
+
+An unavailable thermistor reading returns ``ENODATA``. A malformed fan
+response or an incomplete bus transfer returns an error, not a zero speed.
diff --git a/MAINTAINERS b/MAINTAINERS
index 6215fcb07..c3c208602 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -22440,6 +22440,7 @@ M:	Anvesh Jain P <anvesh.p@oss.qualcomm.com>
 M:	Sibi Sankar <sibi.sankar@oss.qualcomm.com>
 L:	linux-arm-msm@vger.kernel.org
 S:	Maintained
+F:	Documentation/admin-guide/laptops/qcom-ec.rst
 F:	Documentation/devicetree/bindings/embedded-controller/qcom,hamoa-crd-ec.yaml
 F:	drivers/platform/arm64/qcom-hamoa-ec.c
 
diff --git a/drivers/platform/arm64/Kconfig b/drivers/platform/arm64/Kconfig
index e32e01b2a..4f338c715 100644
--- a/drivers/platform/arm64/Kconfig
+++ b/drivers/platform/arm64/Kconfig
@@ -94,6 +94,7 @@ config EC_QCOM_HAMOA
 	tristate "Embedded Controller driver for Qualcomm Hamoa/Glymur reference devices"
 	depends on ARCH_QCOM || COMPILE_TEST
 	depends on I2C
+	depends on HWMON
 	depends on THERMAL || THERMAL=n
 	help
 	  Say M or Y here to enable the Embedded Controller driver for Qualcomm
@@ -101,6 +102,7 @@ config EC_QCOM_HAMOA
 	  control, temperature sensors, access to EC state changes and supports
 	  reporting suspend entry/exit to the EC.
 
-	  This driver currently supports Hamoa/Purwa/Glymur reference devices.
+	  This driver supports Hamoa/Purwa/Glymur reference devices and read-only
+	  fan speed and temperature monitoring on the Lenovo Yoga Slim 7x.
 
 endif # ARM64_PLATFORM_DEVICES
diff --git a/drivers/platform/arm64/qcom-hamoa-ec.c b/drivers/platform/arm64/qcom-hamoa-ec.c
index 4d2ad042a..3a4ca8a0d 100644
--- a/drivers/platform/arm64/qcom-hamoa-ec.c
+++ b/drivers/platform/arm64/qcom-hamoa-ec.c
@@ -9,6 +9,7 @@
 #include <linux/device.h>
 #include <linux/dev_printk.h>
 #include <linux/err.h>
+#include <linux/hwmon.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
@@ -16,10 +17,13 @@
 #include <linux/pm.h>
 #include <linux/slab.h>
 #include <linux/thermal.h>
+#include <linux/unaligned.h>
 
 #define EC_SCI_EVT_READ_CMD	0x05
 #define EC_FW_VERSION_CMD	0x0e
+#define EC_FAN_RPM_QUERY_CMD	0x22
 #define EC_MODERN_STANDBY_CMD	0x23
+#define EC_THERMISTOR1_CMD	0x29
 #define EC_FAN_DBG_CONTROL_CMD	0x30
 #define EC_SCI_EVT_CONTROL_CMD	0x35
 #define EC_THERMAL_CAP_CMD	0x42
@@ -76,13 +80,126 @@ struct qcom_ec_cooling_dev {
 	u8 state;
 };
 
+struct qcom_ec_variant {
+	bool monitor_only;
+};
+
 struct qcom_ec {
+	const struct qcom_ec_variant *variant;
 	struct qcom_ec_cooling_dev *ec_cdev;
 	struct qcom_ec_thermal_cap thermal_cap;
 	struct qcom_ec_version version;
 	struct i2c_client *client;
 };
 
+/* FC22 in the Slim 7x DSDT: command, fan ID; count, little-endian RPM. */
+static int qcom_ec_read_fan_rpm(struct qcom_ec *ec, long *val)
+{
+	struct i2c_client *client = ec->client;
+	u8 request[] = { EC_FAN_RPM_QUERY_CMD, 1 };
+	u8 response[3];
+	struct i2c_msg messages[] = {
+		{
+			.addr = client->addr,
+			.len = sizeof(request),
+			.buf = request,
+		}, {
+			.addr = client->addr,
+			.flags = I2C_M_RD,
+			.len = sizeof(response),
+			.buf = response,
+		},
+	};
+	int ret;
+
+	ret = i2c_transfer(client->adapter, messages, ARRAY_SIZE(messages));
+	if (ret < 0)
+		return ret;
+	if (ret != ARRAY_SIZE(messages))
+		return -EIO;
+	if (response[0] != sizeof(response) - 1)
+		return -EPROTO;
+
+	*val = get_unaligned_le16(&response[1]);
+
+	return 0;
+}
+
+static umode_t qcom_ec_hwmon_is_visible(const void *data, enum hwmon_sensor_types type,
+					u32 attr, int channel)
+{
+	if (channel)
+		return 0;
+	if ((type == hwmon_fan && attr == hwmon_fan_input) ||
+	    (type == hwmon_temp && attr == hwmon_temp_input))
+		return 0444;
+
+	return 0;
+}
+
+static int qcom_ec_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
+			      u32 attr, int channel, long *val)
+{
+	struct qcom_ec *ec = dev_get_drvdata(dev);
+	int ret;
+
+	if (channel)
+		return -EOPNOTSUPP;
+
+	if (type == hwmon_fan && attr == hwmon_fan_input)
+		return qcom_ec_read_fan_rpm(ec, val);
+
+	if (type != hwmon_temp || attr != hwmon_temp_input)
+		return -EOPNOTSUPP;
+
+	/* FC29/TZ39 report degrees Celsius, or 0xff if unavailable. */
+	ret = i2c_smbus_read_byte_data(ec->client, EC_THERMISTOR1_CMD);
+	if (ret < 0)
+		return ret;
+	if (ret == 0xff)
+		return -ENODATA;
+
+	*val = ret * 1000;
+
+	return 0;
+}
+
+static const struct hwmon_ops qcom_ec_hwmon_ops = {
+	.is_visible = qcom_ec_hwmon_is_visible,
+	.read = qcom_ec_hwmon_read,
+};
+
+static const struct hwmon_channel_info * const qcom_ec_hwmon_info[] = {
+	HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
+	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
+	NULL,
+};
+
+static const struct hwmon_chip_info qcom_ec_hwmon_chip_info = {
+	.ops = &qcom_ec_hwmon_ops,
+	.info = qcom_ec_hwmon_info,
+};
+
+static int qcom_ec_hwmon_probe(struct qcom_ec *ec)
+{
+	struct device *dev = &ec->client->dev;
+	struct device *hwmon;
+	long rpm;
+	int ret;
+
+	if (!i2c_check_functionality(ec->client->adapter,
+				     I2C_FUNC_I2C | I2C_FUNC_SMBUS_READ_BYTE_DATA))
+		return -EOPNOTSUPP;
+
+	ret = qcom_ec_read_fan_rpm(ec, &rpm);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to read fan RPM\n");
+
+	hwmon = devm_hwmon_device_register_with_info(dev, "qcom_ec", ec,
+						     &qcom_ec_hwmon_chip_info, NULL);
+	return PTR_ERR_OR_ZERO(hwmon);
+}
+
 static int qcom_ec_read(struct qcom_ec *ec, u8 cmd, u8 resp_len, u8 *resp)
 {
 	int ret;
@@ -331,6 +448,10 @@ static const struct thermal_cooling_device_ops qcom_ec_thermal_ops = {
 static int qcom_ec_resume(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
+	struct qcom_ec *ec = i2c_get_clientdata(client);
+
+	if (ec->variant->monitor_only)
+		return 0;
 
 	return i2c_smbus_write_byte_data(client, EC_MODERN_STANDBY_CMD,
 					 EC_MODERN_STANDBY_EXIT);
@@ -339,6 +460,10 @@ static int qcom_ec_resume(struct device *dev)
 static int qcom_ec_suspend(struct device *dev)
 {
 	struct i2c_client *client = to_i2c_client(dev);
+	struct qcom_ec *ec = i2c_get_clientdata(client);
+
+	if (ec->variant->monitor_only)
+		return 0;
 
 	return i2c_smbus_write_byte_data(client, EC_MODERN_STANDBY_CMD,
 					 EC_MODERN_STANDBY_ENTER);
@@ -356,14 +481,24 @@ static int qcom_ec_probe(struct i2c_client *client)
 		return -ENOMEM;
 
 	ec->client = client;
+	ec->variant = i2c_get_match_data(client);
+	if (!ec->variant)
+		return -ENODEV;
+	i2c_set_clientdata(client, ec);
+
+	/*
+	 * The Slim 7x does not implement the reference-board capability command.
+	 * Its firmware controls cooling autonomously. Only expose its legacy
+	 * sensors; do not enable SCI, fan debug control or standby notifications.
+	 */
+	if (ec->variant->monitor_only)
+		return qcom_ec_hwmon_probe(ec);
 
 	ret = devm_request_threaded_irq(dev, client->irq, NULL, qcom_ec_irq,
 					IRQF_ONESHOT, "qcom_ec", ec);
 	if (ret < 0)
 		return ret;
 
-	i2c_set_clientdata(client, ec);
-
 	ret = qcom_ec_read_fw_version(dev);
 	if (ret < 0)
 		return dev_err_probe(dev, ret, "Failed to read EC firmware version\n");
@@ -410,6 +545,9 @@ static void qcom_ec_remove(struct i2c_client *client)
 	struct device *dev = &client->dev;
 	int ret;
 
+	if (ec->variant->monitor_only)
+		return;
+
 	ret = qcom_ec_sci_evt_control(dev, false);
 	if (ret < 0)
 		dev_err(dev, "Failed to disable SCI events: %d\n", ret);
@@ -421,14 +559,21 @@ static void qcom_ec_remove(struct i2c_client *client)
 	}
 }
 
+static const struct qcom_ec_variant qcom_ec_reference = {};
+
+static const struct qcom_ec_variant qcom_ec_slim7x = {
+	.monitor_only = true,
+};
+
 static const struct of_device_id qcom_ec_of_match[] = {
-	{ .compatible = "qcom,hamoa-crd-ec" },
+	{ .compatible = "lenovo,yoga-slim7x-ec", .data = &qcom_ec_slim7x },
+	{ .compatible = "qcom,hamoa-crd-ec", .data = &qcom_ec_reference },
 	{}
 };
 MODULE_DEVICE_TABLE(of, qcom_ec_of_match);
 
 static const struct i2c_device_id qcom_ec_i2c_id_table[] = {
-	{ "qcom-hamoa-ec", },
+	{ "qcom-hamoa-ec", (kernel_ulong_t)&qcom_ec_reference },
 	{}
 };
 MODULE_DEVICE_TABLE(i2c, qcom_ec_i2c_id_table);
-- 
2.53.0

Re: [RFC PATCH v2 1/2] platform: arm64: qcom-hamoa-ec: monitor Slim 7x legacy sensors

[Birk Skyum]

Hi Anvesh,

Sashiko flagged the pre-existing SCI cleanup gap on the reference-board
probe path. I reproduced it in KUnit with simulated I2C and IRQ devices:
when the thermal-capability read fails, SCI remains enabled after the
driver core releases the interrupt.

I noticed you already proposed the devm_add_action_or_reset() conversion
and agreed to split it out after Konrad's review:
https://lkml.iu.edu/hypermail/linux/kernel/2607.3/10628.html

With that conversion applied locally, the failure-path and removal tests
pass. Is there a standalone version available to test? Happy to share the
reproducer if useful. I'll keep this separate from the Yoga sensor RFC.

For the other v2 findings, I've queued the named I2C initializers for the
next revision. Guenter left the driver split to me, and v2 already moved
the documentation out of Documentation/hwmon as requested.

Thanks,
Birk

Re: [RFC PATCH v2 1/2] platform: arm64: qcom-hamoa-ec: monitor Slim 7x legacy sensors

[Anvesh Jain P]

On 9/8/2026 8:06 PM, Birk Skyum wrote:
> Hi Anvesh,
> 
> Sashiko flagged the pre-existing SCI cleanup gap on the reference-board
> probe path. I reproduced it in KUnit with simulated I2C and IRQ devices:
> when the thermal-capability read fails, SCI remains enabled after the
> driver core releases the interrupt.
> 
> I noticed you already proposed the devm_add_action_or_reset() conversion
> and agreed to split it out after Konrad's review:
> https://lkml.iu.edu/hypermail/linux/kernel/2607.3/10628.html
> 
> With that conversion applied locally, the failure-path and removal tests
> pass. Is there a standalone version available to test? Happy to share the
> reproducer if useful. I'll keep this separate from the Yoga sensor RFC.
> 
> For the other v2 findings, I've queued the named I2C initializers for the
> next revision. Guenter left the driver split to me, and v2 already moved
> the documentation out of Documentation/hwmon as requested.
> 
> Thanks,
> Birk

Hi Birk,

Yes, we already have that fix, SCI disable is now registered as a devm
action right after it's enabled in probe, so it unwinds on any probe
failure, not just on remove(). Same for the i2c_device_id
named-initializer thing bot flagged.

I'm working on v2 right now. Once I get consensus on all the review
comments, I'll post it with these fixes included very soon, once it's
out so you can test against your reproducer.

-- 
Best Regards,
Anvesh

Re: [RFC PATCH v2 1/2] platform: arm64: qcom-hamoa-ec: monitor Slim 7x legacy sensors

[Anvesh Jain P]

On 9/8/2026 7:28 PM, Birk Skyum wrote:
> The Yoga Slim 7x EC returns an all-zero response to the reference-board
> thermal capability command. Probe fails even though its legacy RPM and
> thermistor queries work and firmware controls the fan automatically.
> 
> Select a read-only path for the Lenovo compatible. Expose its first RPM
> channel and thermistor through hwmon, validating the transfer length and
> RPM payload count and treating the thermistor's 0xff sentinel as ENODATA.
> Do not enable SCI, register manual cooling controls or send standby
> commands on this path. Keep the reference-board behavior and strict
> capability validation unchanged.
> 
> The transactions are documented by the Yoga's FC22 and FC29/TZ39 DSDT
> methods and Maya Matuszczyk's EC protocol notes. Anvesh Jain P's pending
> fan-profile series also documents the RPM query. This change does not
> include its calibration, LUT programming or temperature reporting.
> 
> Link: https://github.com/aarch64-laptops/build/blob/2e58842f5fa2f87771c2df017ae4d8c65225ef10/misc/lenovo-yoga-slim-7x/acpi/dsdt.dsl
> Link: https://lkml.iu.edu/hypermail/linux/kernel/2607.3/08806.html
> Signed-off-by: Birk Skyum <birk.skyum@pm.me>
> ---
> Changes in v2:
> - Move the platform-driver documentation to the laptop-driver guide and
>   update its index and MAINTAINERS entry, following Guenter's review.
> - No driver code changes.
> 
>  Documentation/admin-guide/laptops/index.rst   |   1 +
>  Documentation/admin-guide/laptops/qcom-ec.rst |  40 +++++
>  MAINTAINERS                                   |   1 +
>  drivers/platform/arm64/Kconfig                |   4 +-
>  drivers/platform/arm64/qcom-hamoa-ec.c        | 153 +++++++++++++++++-
>  5 files changed, 194 insertions(+), 5 deletions(-)
>  create mode 100644 Documentation/admin-guide/laptops/qcom-ec.rst
> 
> diff --git a/Documentation/admin-guide/laptops/index.rst b/Documentation/admin-guide/laptops/index.rst
> index c0b911d05..44c9c7c08 100644
> --- a/Documentation/admin-guide/laptops/index.rst
> +++ b/Documentation/admin-guide/laptops/index.rst
> @@ -11,6 +11,7 @@ Laptop Drivers
>     asus-laptop
>     disk-shock-protection
>     lg-laptop
> +   qcom-ec
>     samsung-galaxybook
>     sony-laptop
>     sonypi
> diff --git a/Documentation/admin-guide/laptops/qcom-ec.rst b/Documentation/admin-guide/laptops/qcom-ec.rst
> new file mode 100644
> index 000000000..11f9f2347
> --- /dev/null
> +++ b/Documentation/admin-guide/laptops/qcom-ec.rst
> @@ -0,0 +1,40 @@
> +.. SPDX-License-Identifier: GPL-2.0-only
> +
> +Kernel driver qcom-hamoa-ec
> +==========================
> +
> +Supported systems:
> +
> +  * Lenovo Yoga Slim 7x (14Q8X9)
> +
> +    Prefix: 'qcom_ec'
> +
> +    I2C address: 0x76, instantiated from the device tree. No scanning.
> +
> +Description
> +-----------
> +
> +The Yoga Slim 7x embedded controller provides a fan speed channel and a
> +thermistor through a legacy interface. It does not provide the thermal
> +capability response used by the Qualcomm reference-board interface.
> +
> +On this system the driver only reads sensors. Cooling remains under firmware
> +control, including when the driver is unloaded. The driver does not change
> +fan curves, fan profiles, PWM settings, SCI events or EC standby state.
> +The exposed RPM channel does not establish the number of physical fans.
> +
> +The hwmon interface is selected by the ``lenovo,yoga-slim7x-ec`` compatible.
> +It is not exposed on Qualcomm reference boards by this driver.
> +
> +Sysfs attributes
> +----------------
> +
> +All attributes below are read-only.
> +
> +=============== ======================================================
> +fan1_input      Fan speed in RPM. Zero is valid when the fan is stopped.
> +temp1_input     EC thermistor temperature in millidegrees Celsius.
> +=============== ======================================================
> +
> +An unavailable thermistor reading returns ``ENODATA``. A malformed fan
> +response or an incomplete bus transfer returns an error, not a zero speed.
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 6215fcb07..c3c208602 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -22440,6 +22440,7 @@ M:	Anvesh Jain P <anvesh.p@oss.qualcomm.com>
>  M:	Sibi Sankar <sibi.sankar@oss.qualcomm.com>
>  L:	linux-arm-msm@vger.kernel.org
>  S:	Maintained
> +F:	Documentation/admin-guide/laptops/qcom-ec.rst
>  F:	Documentation/devicetree/bindings/embedded-controller/qcom,hamoa-crd-ec.yaml
>  F:	drivers/platform/arm64/qcom-hamoa-ec.c
>  
> diff --git a/drivers/platform/arm64/Kconfig b/drivers/platform/arm64/Kconfig
> index e32e01b2a..4f338c715 100644
> --- a/drivers/platform/arm64/Kconfig
> +++ b/drivers/platform/arm64/Kconfig
> @@ -94,6 +94,7 @@ config EC_QCOM_HAMOA
>  	tristate "Embedded Controller driver for Qualcomm Hamoa/Glymur reference devices"
>  	depends on ARCH_QCOM || COMPILE_TEST
>  	depends on I2C
> +	depends on HWMON
>  	depends on THERMAL || THERMAL=n
>  	help
>  	  Say M or Y here to enable the Embedded Controller driver for Qualcomm
> @@ -101,6 +102,7 @@ config EC_QCOM_HAMOA
>  	  control, temperature sensors, access to EC state changes and supports
>  	  reporting suspend entry/exit to the EC.
>  
> -	  This driver currently supports Hamoa/Purwa/Glymur reference devices.
> +	  This driver supports Hamoa/Purwa/Glymur reference devices and read-only
> +	  fan speed and temperature monitoring on the Lenovo Yoga Slim 7x.
>  
>  endif # ARM64_PLATFORM_DEVICES
> diff --git a/drivers/platform/arm64/qcom-hamoa-ec.c b/drivers/platform/arm64/qcom-hamoa-ec.c
> index 4d2ad042a..3a4ca8a0d 100644
> --- a/drivers/platform/arm64/qcom-hamoa-ec.c
> +++ b/drivers/platform/arm64/qcom-hamoa-ec.c
> @@ -9,6 +9,7 @@
>  #include <linux/device.h>
>  #include <linux/dev_printk.h>
>  #include <linux/err.h>
> +#include <linux/hwmon.h>
>  #include <linux/i2c.h>
>  #include <linux/interrupt.h>
>  #include <linux/kernel.h>
> @@ -16,10 +17,13 @@
>  #include <linux/pm.h>
>  #include <linux/slab.h>
>  #include <linux/thermal.h>
> +#include <linux/unaligned.h>
>  
>  #define EC_SCI_EVT_READ_CMD	0x05
>  #define EC_FW_VERSION_CMD	0x0e
> +#define EC_FAN_RPM_QUERY_CMD	0x22
>  #define EC_MODERN_STANDBY_CMD	0x23
> +#define EC_THERMISTOR1_CMD	0x29
>  #define EC_FAN_DBG_CONTROL_CMD	0x30
>  #define EC_SCI_EVT_CONTROL_CMD	0x35
>  #define EC_THERMAL_CAP_CMD	0x42
> @@ -76,13 +80,126 @@ struct qcom_ec_cooling_dev {
>  	u8 state;
>  };
>  
> +struct qcom_ec_variant {
> +	bool monitor_only;
> +};
> +
>  struct qcom_ec {
> +	const struct qcom_ec_variant *variant;
>  	struct qcom_ec_cooling_dev *ec_cdev;
>  	struct qcom_ec_thermal_cap thermal_cap;
>  	struct qcom_ec_version version;
>  	struct i2c_client *client;
>  };
>  
> +/* FC22 in the Slim 7x DSDT: command, fan ID; count, little-endian RPM. */
> +static int qcom_ec_read_fan_rpm(struct qcom_ec *ec, long *val)
> +{
> +	struct i2c_client *client = ec->client;
> +	u8 request[] = { EC_FAN_RPM_QUERY_CMD, 1 };
> +	u8 response[3];
> +	struct i2c_msg messages[] = {
> +		{
> +			.addr = client->addr,
> +			.len = sizeof(request),
> +			.buf = request,
> +		}, {
> +			.addr = client->addr,
> +			.flags = I2C_M_RD,
> +			.len = sizeof(response),
> +			.buf = response,
> +		},
> +	};
> +	int ret;
> +
> +	ret = i2c_transfer(client->adapter, messages, ARRAY_SIZE(messages));
> +	if (ret < 0)
> +		return ret;
> +	if (ret != ARRAY_SIZE(messages))
> +		return -EIO;
> +	if (response[0] != sizeof(response) - 1)
> +		return -EPROTO;
> +
> +	*val = get_unaligned_le16(&response[1]);
> +
> +	return 0;
> +}
> +
> +static umode_t qcom_ec_hwmon_is_visible(const void *data, enum hwmon_sensor_types type,
> +					u32 attr, int channel)
> +{
> +	if (channel)
> +		return 0;
> +	if ((type == hwmon_fan && attr == hwmon_fan_input) ||
> +	    (type == hwmon_temp && attr == hwmon_temp_input))
> +		return 0444;
> +
> +	return 0;
> +}
> +
> +static int qcom_ec_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
> +			      u32 attr, int channel, long *val)
> +{
> +	struct qcom_ec *ec = dev_get_drvdata(dev);
> +	int ret;
> +
> +	if (channel)
> +		return -EOPNOTSUPP;
> +
> +	if (type == hwmon_fan && attr == hwmon_fan_input)
> +		return qcom_ec_read_fan_rpm(ec, val);
> +
> +	if (type != hwmon_temp || attr != hwmon_temp_input)
> +		return -EOPNOTSUPP;
> +
> +	/* FC29/TZ39 report degrees Celsius, or 0xff if unavailable. */
> +	ret = i2c_smbus_read_byte_data(ec->client, EC_THERMISTOR1_CMD);

For the thermistor, it may be better to expose it as a thermal sensor
and create a thermal zone instead of exposing it as a hwmon temperature
attribute. The fan RPM can remain under hwmon.

> +	if (ret < 0)
> +		return ret;
> +	if (ret == 0xff)
> +		return -ENODATA;
> +
> +	*val = ret * 1000;
> +
> +	return 0;
> +}
> +
> +static const struct hwmon_ops qcom_ec_hwmon_ops = {
> +	.is_visible = qcom_ec_hwmon_is_visible,
> +	.read = qcom_ec_hwmon_read,
> +};
> +
> +static const struct hwmon_channel_info * const qcom_ec_hwmon_info[] = {
> +	HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
> +	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
> +	NULL,
> +};
> +
> +static const struct hwmon_chip_info qcom_ec_hwmon_chip_info = {
> +	.ops = &qcom_ec_hwmon_ops,
> +	.info = qcom_ec_hwmon_info,
> +};
> +
> +static int qcom_ec_hwmon_probe(struct qcom_ec *ec)
> +{
> +	struct device *dev = &ec->client->dev;
> +	struct device *hwmon;
> +	long rpm;
> +	int ret;
> +
> +	if (!i2c_check_functionality(ec->client->adapter,
> +				     I2C_FUNC_I2C | I2C_FUNC_SMBUS_READ_BYTE_DATA))
> +		return -EOPNOTSUPP;
> +
> +	ret = qcom_ec_read_fan_rpm(ec, &rpm);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to read fan RPM\n");
> +
> +	hwmon = devm_hwmon_device_register_with_info(dev, "qcom_ec", ec,
> +						     &qcom_ec_hwmon_chip_info, NULL);
> +	return PTR_ERR_OR_ZERO(hwmon);
> +}
> +
>  static int qcom_ec_read(struct qcom_ec *ec, u8 cmd, u8 resp_len, u8 *resp)
>  {
>  	int ret;
> @@ -331,6 +448,10 @@ static const struct thermal_cooling_device_ops qcom_ec_thermal_ops = {
>  static int qcom_ec_resume(struct device *dev)
>  {
>  	struct i2c_client *client = to_i2c_client(dev);
> +	struct qcom_ec *ec = i2c_get_clientdata(client);
> +
> +	if (ec->variant->monitor_only)
> +		return 0;
>  
>  	return i2c_smbus_write_byte_data(client, EC_MODERN_STANDBY_CMD,
>  					 EC_MODERN_STANDBY_EXIT);
> @@ -339,6 +460,10 @@ static int qcom_ec_resume(struct device *dev)
>  static int qcom_ec_suspend(struct device *dev)
>  {
>  	struct i2c_client *client = to_i2c_client(dev);
> +	struct qcom_ec *ec = i2c_get_clientdata(client);
> +
> +	if (ec->variant->monitor_only)
> +		return 0;
>  
>  	return i2c_smbus_write_byte_data(client, EC_MODERN_STANDBY_CMD,
>  					 EC_MODERN_STANDBY_ENTER);
> @@ -356,14 +481,24 @@ static int qcom_ec_probe(struct i2c_client *client)
>  		return -ENOMEM;
>  
>  	ec->client = client;
> +	ec->variant = i2c_get_match_data(client);
> +	if (!ec->variant)
> +		return -ENODEV;
> +	i2c_set_clientdata(client, ec);
> +
> +	/*
> +	 * The Slim 7x does not implement the reference-board capability command.
> +	 * Its firmware controls cooling autonomously. Only expose its legacy
> +	 * sensors; do not enable SCI, fan debug control or standby notifications.
> +	 */
> +	if (ec->variant->monitor_only)
> +		return qcom_ec_hwmon_probe(ec);
>  
>  	ret = devm_request_threaded_irq(dev, client->irq, NULL, qcom_ec_irq,
>  					IRQF_ONESHOT, "qcom_ec", ec);
>  	if (ret < 0)
>  		return ret;
>  
> -	i2c_set_clientdata(client, ec);
> -
>  	ret = qcom_ec_read_fw_version(dev);
>  	if (ret < 0)
>  		return dev_err_probe(dev, ret, "Failed to read EC firmware version\n");
> @@ -410,6 +545,9 @@ static void qcom_ec_remove(struct i2c_client *client)
>  	struct device *dev = &client->dev;
>  	int ret;
>  
> +	if (ec->variant->monitor_only)
> +		return;
> +
>  	ret = qcom_ec_sci_evt_control(dev, false);
>  	if (ret < 0)
>  		dev_err(dev, "Failed to disable SCI events: %d\n", ret);
> @@ -421,14 +559,21 @@ static void qcom_ec_remove(struct i2c_client *client)
>  	}
>  }
>  
> +static const struct qcom_ec_variant qcom_ec_reference = {};
> +
> +static const struct qcom_ec_variant qcom_ec_slim7x = {
> +	.monitor_only = true,
> +};
> +
>  static const struct of_device_id qcom_ec_of_match[] = {
> -	{ .compatible = "qcom,hamoa-crd-ec" },
> +	{ .compatible = "lenovo,yoga-slim7x-ec", .data = &qcom_ec_slim7x },
> +	{ .compatible = "qcom,hamoa-crd-ec", .data = &qcom_ec_reference },
>  	{}
>  };
>  MODULE_DEVICE_TABLE(of, qcom_ec_of_match);
>  
>  static const struct i2c_device_id qcom_ec_i2c_id_table[] = {
> -	{ "qcom-hamoa-ec", },
> +	{ "qcom-hamoa-ec", (kernel_ulong_t)&qcom_ec_reference },
>  	{}
>  };
>  MODULE_DEVICE_TABLE(i2c, qcom_ec_i2c_id_table);

-- 
Best Regards,
Anvesh

[RFC PATCH v2 2/2] platform: arm64: qcom-hamoa-ec: test sensor and variant handling

[Birk Skyum]

Exercise the sensor callbacks against a simulated I2C adapter. Check
little-endian RPM decoding, short transfers, malformed byte counts,
the unavailable-temperature sentinel and propagation of bus errors.

Check that the Lenovo compatible takes precedence over its reference-
board fallback, that its sensor attributes are read-only, and that its
probe and PM/remove callbacks do not issue control writes. Keep coverage
of the strict reference-board capability-response validation.

The tests use KUnit and never access a physical EC.

Signed-off-by: Birk Skyum <birk.skyum@pm.me>
---
 MAINTAINERS                                 |   1 +
 drivers/platform/arm64/Kconfig              |  12 +
 drivers/platform/arm64/qcom-hamoa-ec-test.c | 294 ++++++++++++++++++++
 drivers/platform/arm64/qcom-hamoa-ec.c      |   4 +
 4 files changed, 311 insertions(+)
 create mode 100644 drivers/platform/arm64/qcom-hamoa-ec-test.c

diff --git a/MAINTAINERS b/MAINTAINERS
index c3c208602..53ad3ca48 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -22442,6 +22442,7 @@ L:	linux-arm-msm@vger.kernel.org
 S:	Maintained
 F:	Documentation/admin-guide/laptops/qcom-ec.rst
 F:	Documentation/devicetree/bindings/embedded-controller/qcom,hamoa-crd-ec.yaml
+F:	drivers/platform/arm64/qcom-hamoa-ec-test.c
 F:	drivers/platform/arm64/qcom-hamoa-ec.c
 
 QUALCOMM HEXAGON ARCHITECTURE
diff --git a/drivers/platform/arm64/Kconfig b/drivers/platform/arm64/Kconfig
index 4f338c715..d940973be 100644
--- a/drivers/platform/arm64/Kconfig
+++ b/drivers/platform/arm64/Kconfig
@@ -105,4 +105,16 @@ config EC_QCOM_HAMOA
 	  This driver supports Hamoa/Purwa/Glymur reference devices and read-only
 	  fan speed and temperature monitoring on the Lenovo Yoga Slim 7x.
 
+config EC_QCOM_HAMOA_KUNIT_TEST
+	bool "Tests for the Qualcomm EC driver" if !KUNIT_ALL_TESTS
+	depends on EC_QCOM_HAMOA && KUNIT && OF
+	depends on EC_QCOM_HAMOA=m || KUNIT=y
+	default KUNIT_ALL_TESTS
+	help
+	  Test the Qualcomm EC driver's sensor transactions and read-only
+	  callbacks using a simulated I2C adapter. No physical EC is accessed.
+	  Run these tests in a disposable test kernel, for example under QEMU.
+
+	  If unsure, say N.
+
 endif # ARM64_PLATFORM_DEVICES
diff --git a/drivers/platform/arm64/qcom-hamoa-ec-test.c b/drivers/platform/arm64/qcom-hamoa-ec-test.c
new file mode 100644
index 000000000..68868ef76
--- /dev/null
+++ b/drivers/platform/arm64/qcom-hamoa-ec-test.c
@@ -0,0 +1,294 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Included by qcom-hamoa-ec.c to test its private transport and callbacks. */
+
+#include <kunit/resource.h>
+#include <kunit/test.h>
+#include <linux/of.h>
+
+struct qcom_ec_test_context {
+	struct i2c_adapter adapter;
+	struct qcom_ec ec;
+	u32 functionality;
+	int transfer_result;
+	int byte_result;
+	u8 reply[4];
+	u8 block_length;
+	unsigned int transactions;
+	unsigned int writes;
+};
+
+static int qcom_ec_test_transfer(struct i2c_adapter *adapter,
+				 struct i2c_msg *messages, int count)
+{
+	struct qcom_ec_test_context *ctx = i2c_get_adapdata(adapter);
+
+	ctx->transactions++;
+	/* Only the RPM query's combined write/read transaction is allowed. */
+	if (count != 2 || messages[0].addr != 0x76 || messages[1].addr != 0x76 ||
+	    messages[0].flags || messages[1].flags != I2C_M_RD ||
+	    messages[0].len != 2 || messages[1].len != 3 ||
+	    messages[0].buf[0] != 0x22 || messages[0].buf[1] != 1) {
+		ctx->writes++;
+		return -EPROTO;
+	}
+
+	if (ctx->transfer_result == 2)
+		memcpy(messages[1].buf, ctx->reply, messages[1].len);
+
+	return ctx->transfer_result;
+}
+
+static s32 qcom_ec_test_smbus(struct i2c_adapter *adapter, u16 address,
+			      unsigned short flags, char read_write, u8 command,
+			      int size, union i2c_smbus_data *data)
+{
+	struct qcom_ec_test_context *ctx = i2c_get_adapdata(adapter);
+
+	ctx->transactions++;
+	if (read_write != I2C_SMBUS_READ) {
+		ctx->writes++;
+		return -EPROTO;
+	}
+	if (address != 0x76 || flags)
+		return -EPROTO;
+
+	if (command == 0x29 && size == I2C_SMBUS_BYTE_DATA) {
+		if (ctx->byte_result < 0)
+			return ctx->byte_result;
+		data->byte = ctx->byte_result;
+		return 0;
+	}
+
+	if ((command == 0x0e || command == 0x42) && size == I2C_SMBUS_I2C_BLOCK_DATA) {
+		data->block[0] = ctx->block_length;
+		memcpy(&data->block[1], ctx->reply, ctx->block_length);
+		return 0;
+	}
+
+	return -EPROTO;
+}
+
+static u32 qcom_ec_test_functionality(struct i2c_adapter *adapter)
+{
+	struct qcom_ec_test_context *ctx = i2c_get_adapdata(adapter);
+
+	return ctx->functionality;
+}
+
+static const struct i2c_algorithm qcom_ec_test_algorithm = {
+	.master_xfer = qcom_ec_test_transfer,
+	.smbus_xfer = qcom_ec_test_smbus,
+	.functionality = qcom_ec_test_functionality,
+};
+
+static void qcom_ec_test_delete_adapter(void *data)
+{
+	i2c_del_adapter(data);
+}
+
+static void qcom_ec_test_unregister_client(void *data)
+{
+	i2c_unregister_device(data);
+}
+
+static int qcom_ec_test_init(struct kunit *test)
+{
+	struct qcom_ec_test_context *ctx;
+	int ret;
+
+	ctx = kunit_kzalloc(test, sizeof(*ctx), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, ctx);
+	test->priv = ctx;
+	ctx->functionality = I2C_FUNC_I2C | I2C_FUNC_SMBUS_READ_BYTE_DATA |
+			     I2C_FUNC_SMBUS_READ_I2C_BLOCK;
+	ctx->transfer_result = 2;
+	ctx->reply[0] = 2;
+	ctx->byte_result = 36;
+	ctx->adapter.owner = THIS_MODULE;
+	ctx->adapter.algo = &qcom_ec_test_algorithm;
+	strscpy(ctx->adapter.name, "qcom-ec-kunit", sizeof(ctx->adapter.name));
+	i2c_set_adapdata(&ctx->adapter, ctx);
+	ret = i2c_add_adapter(&ctx->adapter);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+	ret = kunit_add_action_or_reset(test, qcom_ec_test_delete_adapter, &ctx->adapter);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	ctx->ec.client = i2c_new_dummy_device(&ctx->adapter, 0x76);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx->ec.client);
+	ret = kunit_add_action_or_reset(test, qcom_ec_test_unregister_client, ctx->ec.client);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+	ctx->ec.variant = &qcom_ec_slim7x;
+	i2c_set_clientdata(ctx->ec.client, &ctx->ec);
+
+	return 0;
+}
+
+static void qcom_ec_rpm_test(struct kunit *test)
+{
+	struct qcom_ec_test_context *ctx = test->priv;
+	static const struct {
+		int transfer_result;
+		u8 count;
+		int error;
+	} failures[] = {
+		{ 0, 2, -EIO },
+		{ 1, 2, -EIO },
+		{ -EREMOTEIO, 2, -EREMOTEIO },
+		{ -ETIMEDOUT, 2, -ETIMEDOUT },
+		{ 2, 0, -EPROTO },
+		{ 2, 1, -EPROTO },
+		{ 2, 3, -EPROTO },
+		{ 2, 0xff, -EPROTO },
+	};
+	long value = -1;
+	int i;
+
+	KUNIT_EXPECT_EQ(test, qcom_ec_read_fan_rpm(&ctx->ec, &value), 0);
+	KUNIT_EXPECT_EQ(test, value, 0);
+	ctx->reply[1] = 0xef;
+	ctx->reply[2] = 0xbe;
+	KUNIT_EXPECT_EQ(test, qcom_ec_read_fan_rpm(&ctx->ec, &value), 0);
+	KUNIT_EXPECT_EQ(test, value, 0xbeef);
+
+	for (i = 0; i < ARRAY_SIZE(failures); i++) {
+		value = -1;
+		ctx->transfer_result = failures[i].transfer_result;
+		ctx->reply[0] = failures[i].count;
+		KUNIT_EXPECT_EQ_MSG(test, qcom_ec_read_fan_rpm(&ctx->ec, &value),
+				    failures[i].error, "case %d", i);
+		KUNIT_EXPECT_EQ(test, value, -1);
+	}
+	KUNIT_EXPECT_EQ(test, ctx->writes, 0);
+}
+
+static void qcom_ec_temperature_test(struct kunit *test)
+{
+	struct qcom_ec_test_context *ctx = test->priv;
+	static const int temperatures[] = { 0, 36, 254, 255, -EREMOTEIO };
+	long value;
+	int i, ret;
+
+	for (i = 0; i < ARRAY_SIZE(temperatures); i++) {
+		value = -1;
+		ctx->byte_result = temperatures[i];
+		ret = qcom_ec_hwmon_read(&ctx->ec.client->dev, hwmon_temp,
+					 hwmon_temp_input, 0, &value);
+		if (temperatures[i] < 0) {
+			KUNIT_EXPECT_EQ(test, ret, temperatures[i]);
+			KUNIT_EXPECT_EQ(test, value, -1);
+		} else if (temperatures[i] == 255) {
+			KUNIT_EXPECT_EQ(test, ret, -ENODATA);
+			KUNIT_EXPECT_EQ(test, value, -1);
+		} else {
+			KUNIT_EXPECT_EQ(test, ret, 0);
+			KUNIT_EXPECT_EQ(test, value, temperatures[i] * 1000);
+		}
+	}
+	KUNIT_EXPECT_EQ(test, ctx->writes, 0);
+}
+
+static void qcom_ec_read_only_test(struct kunit *test)
+{
+	struct qcom_ec_test_context *ctx = test->priv;
+	struct device *dev = &ctx->ec.client->dev;
+	long value = -1;
+
+	KUNIT_EXPECT_EQ(test, qcom_ec_hwmon_is_visible(NULL, hwmon_fan, hwmon_fan_input, 0),
+			0444);
+	KUNIT_EXPECT_EQ(test, qcom_ec_hwmon_is_visible(NULL, hwmon_temp, hwmon_temp_input, 0),
+			0444);
+	KUNIT_EXPECT_EQ(test, qcom_ec_hwmon_is_visible(NULL, hwmon_fan, hwmon_fan_input, 1), 0);
+	KUNIT_EXPECT_EQ(test, qcom_ec_hwmon_is_visible(NULL, hwmon_pwm, hwmon_pwm_input, 0), 0);
+	KUNIT_EXPECT_EQ(test, qcom_ec_hwmon_read(dev, hwmon_fan, hwmon_fan_input, 1, &value),
+			-EOPNOTSUPP);
+	KUNIT_EXPECT_EQ(test, qcom_ec_hwmon_read(dev, hwmon_pwm, hwmon_pwm_input, 0, &value),
+			-EOPNOTSUPP);
+	KUNIT_EXPECT_EQ(test, value, -1);
+	KUNIT_EXPECT_EQ(test, qcom_ec_suspend(dev), 0);
+	KUNIT_EXPECT_EQ(test, qcom_ec_resume(dev), 0);
+	qcom_ec_remove(ctx->ec.client);
+	KUNIT_EXPECT_EQ(test, ctx->transactions, 0);
+}
+
+static void qcom_ec_probe_transport_test(struct kunit *test)
+{
+	struct qcom_ec_test_context *ctx = test->priv;
+
+	ctx->functionality = I2C_FUNC_I2C;
+	KUNIT_EXPECT_EQ(test, qcom_ec_hwmon_probe(&ctx->ec), -EOPNOTSUPP);
+	ctx->functionality = I2C_FUNC_SMBUS_READ_BYTE_DATA;
+	KUNIT_EXPECT_EQ(test, qcom_ec_hwmon_probe(&ctx->ec), -EOPNOTSUPP);
+	KUNIT_EXPECT_EQ(test, ctx->transactions, 0);
+}
+
+static void qcom_ec_probe_sensor_test(struct kunit *test)
+{
+	struct qcom_ec_test_context *ctx = test->priv;
+
+	KUNIT_EXPECT_EQ(test, qcom_ec_hwmon_probe(&ctx->ec), 0);
+	KUNIT_EXPECT_EQ(test, ctx->transactions, 1);
+	KUNIT_EXPECT_EQ(test, ctx->writes, 0);
+	ctx->reply[0] = 0;
+	KUNIT_EXPECT_EQ(test, qcom_ec_hwmon_probe(&ctx->ec), -EPROTO);
+	KUNIT_EXPECT_EQ(test, ctx->writes, 0);
+}
+
+static void qcom_ec_reference_validation_test(struct kunit *test)
+{
+	struct qcom_ec_test_context *ctx = test->priv;
+	u8 response[3];
+
+	ctx->block_length = 3;
+	KUNIT_EXPECT_EQ(test, qcom_ec_read(&ctx->ec, EC_THERMAL_CAP_CMD, 3, response), 0);
+	ctx->block_length = 2;
+	KUNIT_EXPECT_EQ(test, qcom_ec_read(&ctx->ec, EC_THERMAL_CAP_CMD, 3, response), -EIO);
+	ctx->block_length = 0;
+	KUNIT_EXPECT_EQ(test, qcom_ec_read(&ctx->ec, EC_THERMAL_CAP_CMD, 3, response),
+			-EOPNOTSUPP);
+	ctx->block_length = 3;
+	ctx->reply[0] = 0;
+	KUNIT_EXPECT_EQ(test, qcom_ec_read(&ctx->ec, EC_THERMAL_CAP_CMD, 3, response), -EINVAL);
+	ctx->reply[0] = 1;
+	KUNIT_EXPECT_EQ(test, qcom_ec_read(&ctx->ec, EC_THERMAL_CAP_CMD, 3, response), -EINVAL);
+	KUNIT_EXPECT_EQ(test, ctx->writes, 0);
+}
+
+static void qcom_ec_variant_test(struct kunit *test)
+{
+	static const char compatible[] = "lenovo,yoga-slim7x-ec\0qcom,hamoa-crd-ec";
+	struct property property = {
+		.name = "compatible",
+		.length = sizeof(compatible),
+		.value = (void *)compatible,
+	};
+	struct device_node node = { .properties = &property };
+	const struct of_device_id *match;
+
+	match = of_match_node(qcom_ec_of_match, &node);
+	KUNIT_ASSERT_NOT_NULL(test, match);
+	KUNIT_EXPECT_PTR_EQ(test, match->data, &qcom_ec_slim7x);
+	property.value = "qcom,hamoa-crd-ec";
+	property.length = sizeof("qcom,hamoa-crd-ec");
+	match = of_match_node(qcom_ec_of_match, &node);
+	KUNIT_ASSERT_NOT_NULL(test, match);
+	KUNIT_EXPECT_PTR_EQ(test, match->data, &qcom_ec_reference);
+}
+
+static struct kunit_case qcom_ec_test_cases[] = {
+	KUNIT_CASE(qcom_ec_rpm_test),
+	KUNIT_CASE(qcom_ec_temperature_test),
+	KUNIT_CASE(qcom_ec_read_only_test),
+	KUNIT_CASE(qcom_ec_probe_transport_test),
+	KUNIT_CASE(qcom_ec_probe_sensor_test),
+	KUNIT_CASE(qcom_ec_reference_validation_test),
+	KUNIT_CASE(qcom_ec_variant_test),
+	{}
+};
+
+static struct kunit_suite qcom_ec_test_suite = {
+	.name = "qcom-hamoa-ec",
+	.init = qcom_ec_test_init,
+	.test_cases = qcom_ec_test_cases,
+};
+
+kunit_test_suite(qcom_ec_test_suite);
diff --git a/drivers/platform/arm64/qcom-hamoa-ec.c b/drivers/platform/arm64/qcom-hamoa-ec.c
index 3a4ca8a0d..043f6ab7e 100644
--- a/drivers/platform/arm64/qcom-hamoa-ec.c
+++ b/drivers/platform/arm64/qcom-hamoa-ec.c
@@ -596,3 +596,7 @@ module_i2c_driver(qcom_ec_i2c_driver);
 
 MODULE_DESCRIPTION("QCOM Hamoa Embedded Controller");
 MODULE_LICENSE("GPL");
+
+#if IS_ENABLED(CONFIG_EC_QCOM_HAMOA_KUNIT_TEST)
+#include "qcom-hamoa-ec-test.c"
+#endif
-- 
2.53.0

Re: [RFC PATCH v2 0/2] Monitor Yoga Slim 7x EC sensors without taking over cooling

[Anvesh Jain P]

On 9/8/2026 7:28 PM, Birk Skyum wrote:
> Two design questions for this RFC:
> - Is this read-only match-data path the preferred way to accommodate
>   the Lenovo firmware alongside the reference-board work?

The read-only match-data path looks fine, but it should be integrated
with the existing LUT match data. We should not replace the current
match-data usage.

> - Should the pending Lenovo binding omit the qcom,hamoa-crd-ec fallback,
>   given that this firmware cannot satisfy the reference driver's probe?

If this firmware cannot pass the reference-board thermal-capability
probe, I think the Lenovo binding should not use qcom,hamoa-crd-ec as a
fallback. The fallback should be used only if the device is functionally
compatible with the reference-board driver, not only because it uses the
same EC chip.

In that case, the binding changes in Daniel’s patch also need to be updated.

-- 
Best Regards,
Anvesh

Re: [RFC PATCH v2 0/2] Monitor Yoga Slim 7x EC sensors without taking over cooling

[Birk Skyum]

Hi Anvesh,

Thanks for the review and for raising the firmware comparison with Daniel.

Agreed on preserving the LUT match data. My v2 is based on
28924df2a08f440c73991b83028032c901de2ae4, which does not contain that
implementation, and I could not find it in the current mainline driver
either. Could you point me to the latest series or branch you would like
me to target? I can integrate the read-only variant with that match data
without changing the existing LUT behavior.

On your thermistor comment on patch 1, would a DT thermal sensor and a
monitoring-only thermal zone, without cooling maps, be the interface you
have in mind? I can keep fan RPM under hwmon and leave cooling under
firmware control.

I also agree that sharing the EC chip is not sufficient to justify the
qcom,hamoa-crd-ec fallback. I would like to compare firmware behavior
before treating the capability-query failure as a model-wide limitation,
then coordinate any binding adjustment with Daniel's series.

For that comparison, my existing September 8 test recorded:

  Yoga Slim 7x 14Q8X9 / 83ED
  BIOS NHCN62WW, EC 0.99.0
  Firmware query 0x0e: 03 00 63 00
  Capability query 0x42: 00 00 00, identical across three reads

The capability transfer completed with three bytes, but its count byte
was zero rather than two. The unmodified driver rejected it with EINVAL.
The separate read-only sensor test successfully read RPM and temperature
while firmware controlled the fans.

These are the earlier results, not a fresh test or evidence that a BIOS
update would or would not resolve it. Daniel, I am happy to compare your
versions and capability response, or repeat targeted read-only checks if
there is a useful difference to investigate.

Thanks,
Birk