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

[Birk Skyum <birk.skyum@pm.me>]

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 8518a97b4..58010a3e4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -22442,6 +22442,7 @@ L:	linux-arm-msm@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/embedded-controller/qcom,hamoa-crd-ec.yaml
 F:	Documentation/hwmon/qcom-ec.rst
+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