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Wed, 18 Mar 2026 10:25:33 -0700 (PDT) Received: from sergio-82n7.fritz.box ([2a01:b600:83d8:1:eddb:b262:41cc:374a]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43b51852ab3sm9600650f8f.12.2026.03.18.10.25.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Mar 2026 10:25:32 -0700 (PDT) From: Sergio Melas To: linux@roeck-us.net Cc: linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org, sergiomelas@gmail.com Subject: [PATCH] hwmon: (yogafan) V3.0 Universal refactor and RLLag filter Date: Wed, 18 Mar 2026 18:25:18 +0100 Message-ID: <20260318172518.91336-1-sergiomelas@gmail.com> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" - Refactor driver to V3.0 Universal Platform Mode for cross-model compatibi= lity. - Add support for dual-fan ACPI paths (FANS, FA2S, FANX) for Legion/Yoga se= ries. - Implement 100ms (10Hz) background heartbeat for constant-frequency sampli= ng. - Implement RLLag (Rate Limited Lag) filter to stabilize jumpy EC RPM data. - Use 10-bit fixed-point integer math to avoid forbidden SSE/floating-point= registers. - Integrate DSTS ACPI modifications to ensure sensor stability during S3 sl= eep cycles. - Provide full documentation for KDE 6 Plasma Sensor compatibility and scal= ing. Signed-off-by: Sergio Melas --- drivers/hwmon/yoga_fan.c | 222 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 222 insertions(+) create mode 100644 drivers/hwmon/yoga_fan.c diff --git a/drivers/hwmon/yoga_fan.c b/drivers/hwmon/yoga_fan.c new file mode 100644 index 000000000..5a9ae631c --- /dev/null +++ b/drivers/hwmon/yoga_fan.c @@ -0,0 +1,222 @@ +// SPDX-License-Identifier: GPL-2.0-only +/** + * yoga_fan.c - Lenovo Yoga/Legion Fan Hardware Monitoring Driver + * + * Copyright (C) 2021-2026 Sergio Melas + * + * This driver provides fan speed monitoring for modern Lenovo Yoga, Legio= n, + * and IdeaPad laptops by interfacing with the Embedded Controller (EC) + * via ACPI. It registers a platform device to ensure compatibility with + * modern HWMON consumers like KDE Plasma 6. + * + * Supported Models: + * - Lenovo Yoga 7 / 14c series (Ryzen/Intel) + * - Lenovo Legion 5 / 7 / Pro series (Dual-fan support) + * - Lenovo Yoga Slim 7 / Pro / Carbon / Nano + * - Lenovo IdeaPad 5 / ThinkBook series + * + * Implementation Details: + * - Fixed static HWMON channel definition for kernel 6.0+ compatibility. + * - Implements a 100ms background worker to ensure RLLag filter consisten= cy. + * - RLLag Formula: x(t) =3D x(t-dt) + clamp(step, -limit, limit) + * where step =3D (input - x) * alpha + */ + + +#include +#include +#include +#include +#include +#include +#include +#include + +#define DRVNAME "yogafan" +#define MAX_FANS 2 + +/* --- RLLAG CONFIGURATION --- */ +#define TS_MS 100 +#define TAU_MS 1000 +#define MAX_SPEED_RPM_S 500 + +#define ALPHA_SCALED ((TS_MS * 1024) / (TAU_MS + TS_MS)) +#define STEP_LIMIT ((MAX_SPEED_RPM_S * TS_MS) / 1000) + +struct yoga_fan_data { + const char *active_paths[MAX_FANS]; + long filtered_val[MAX_FANS]; + struct delayed_work heartbeat; + struct mutex lock; + int fan_count; +}; + +static void yoga_fan_worker(struct work_struct *work) +{ + struct yoga_fan_data *data =3D container_of(work, struct yoga_fan_data, h= eartbeat.work); + unsigned long long raw_acpi; + long rpm, delta, lag_step; + int i; + + mutex_lock(&data->lock); + for (i =3D 0; i < data->fan_count; i++) { + if (ACPI_SUCCESS(acpi_evaluate_integer(NULL, (char *)data->active_paths[= i], NULL, &raw_acpi))) { + rpm =3D (raw_acpi > 0 && raw_acpi <=3D 255) ? ((long)raw_acpi * 100) : = (long)raw_acpi; + + delta =3D rpm - data->filtered_val[i]; + lag_step =3D (delta * ALPHA_SCALED) >> 10; + + if (lag_step > (long)STEP_LIMIT) + lag_step =3D (long)STEP_LIMIT; + else if (lag_step < -(long)STEP_LIMIT) + lag_step =3D -(long)STEP_LIMIT; + + data->filtered_val[i] +=3D lag_step; + + if (data->filtered_val[i] < 50) + data->filtered_val[i] =3D 0; + } + } + mutex_unlock(&data->lock); + + schedule_delayed_work(&data->heartbeat, msecs_to_jiffies(TS_MS)); +} + +static int yoga_fan_read(struct device *dev, enum hwmon_sensor_types type, + u32 attr, int channel, long *val) +{ + struct yoga_fan_data *data =3D dev_get_drvdata(dev); + + if (type !=3D hwmon_fan || attr !=3D hwmon_fan_input) + return -EOPNOTSUPP; + + if (channel >=3D data->fan_count) + return -EINVAL; + + mutex_lock(&data->lock); + *val =3D data->filtered_val[channel]; + mutex_unlock(&data->lock); + + return 0; +} + +static umode_t yoga_fan_is_visible(const void *data, enum hwmon_sensor_typ= es type, + u32 attr, int channel) +{ + const struct yoga_fan_data *fan_data =3D data; + + if (type =3D=3D hwmon_fan && channel < fan_data->fan_count) + return 0444; + + return 0; +} + +static const struct hwmon_ops yoga_fan_hwmon_ops =3D { + .is_visible =3D yoga_fan_is_visible, + .read =3D yoga_fan_read, +}; + +static const struct hwmon_channel_info *yoga_fan_info[] =3D { + HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT, HWMON_F_INPUT), + NULL +}; + +static const struct hwmon_chip_info yoga_fan_chip_info =3D { + .ops =3D &yoga_fan_hwmon_ops, + .info =3D yoga_fan_info, +}; + +static int yoga_fan_probe(struct platform_device *pdev) +{ + struct yoga_fan_data *data; + struct device *hwmon_dev; + acpi_handle handle; + unsigned long long init_raw; + int i; + static const char * const fan_paths[] =3D { + "\\_SB.PCI0.LPC0.EC0.FANS", "\\_SB.PCI0.LPC0.EC0.FA2S", + "\\_SB.PCI0.LPC0.EC0.FAN0", "\\_SB.PCI0.LPC.EC.FAN0", + "\\_SB.PCI0.LPC0.EC.FAN0" + }; + + data =3D devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + mutex_init(&data->lock); + + for (i =3D 0; i < ARRAY_SIZE(fan_paths); i++) { + if (ACPI_SUCCESS(acpi_get_handle(NULL, (char *)fan_paths[i], &handle))) { + data->active_paths[data->fan_count] =3D fan_paths[i]; + + if (ACPI_SUCCESS(acpi_evaluate_integer(NULL, (char *)data->active_paths= [data->fan_count], NULL, &init_raw))) + data->filtered_val[data->fan_count] =3D (init_raw > 0 && init_raw <=3D= 255) ? ((long)init_raw * 100) : (long)init_raw; + + data->fan_count++; + if (data->fan_count >=3D MAX_FANS) + break; + } + } + + if (data->fan_count =3D=3D 0) + return -ENODEV; + + hwmon_dev =3D devm_hwmon_device_register_with_info(&pdev->dev, DRVNAME, + data, &yoga_fan_chip_info, NULL); + + INIT_DELAYED_WORK(&data->heartbeat, yoga_fan_worker); + schedule_delayed_work(&data->heartbeat, msecs_to_jiffies(TS_MS)); + + return PTR_ERR_OR_ZERO(hwmon_dev); +} + +static struct platform_driver yoga_fan_driver =3D { + .driver =3D { .name =3D DRVNAME }, + .probe =3D yoga_fan_probe, +}; + +static struct platform_device *yoga_fan_device; + +static const struct dmi_system_id yoga_dmi_table[] __initconst =3D { + { .ident =3D "Lenovo", .matches =3D { DMI_MATCH(DMI_SYS_VENDOR, "LENOVO")= } }, + { } +}; +MODULE_DEVICE_TABLE(dmi, yoga_dmi_table); + +static int __init yoga_fan_init(void) +{ + int ret; + + if (!dmi_check_system(yoga_dmi_table)) + return -ENODEV; + + ret =3D platform_driver_register(&yoga_fan_driver); + if (ret) + return ret; + + yoga_fan_device =3D platform_device_register_simple(DRVNAME, 0, NULL, 0); + if (IS_ERR(yoga_fan_device)) { + platform_driver_unregister(&yoga_fan_driver); + return PTR_ERR(yoga_fan_device); + } + + return 0; +} + +static void __exit yoga_fan_exit(void) +{ + struct yoga_fan_data *data =3D platform_get_drvdata(yoga_fan_device); + + if (data) + cancel_delayed_work_sync(&data->heartbeat); + + platform_device_unregister(yoga_fan_device); + platform_driver_unregister(&yoga_fan_driver); +} + +module_init(yoga_fan_init); +module_exit(yoga_fan_exit); + +MODULE_AUTHOR("Sergio Melas "); +MODULE_DESCRIPTION("Universal Lenovo Fan Driver v3.0.0"); +MODULE_LICENSE("GPL v2"); --=20 2.53.0