hwmon: (adt7470) Expose fan control via PWM framework

The ADT7470 features four PWM outputs designed to control fans.
Previously, these were only accessible through the legacy hwmon
sysfs interface.

Expose the ADT7470 fan control lines through the generic PWM framework.
This allows generic PWM consumers described in Device Tree, such as
"pwm-fan", to use the device through the "#pwm-cells" property.  This is
particularly necessary for boards where the ADT7470 external temperature
sensors are not populated and the chip is used strictly as a fan
controller (e.g., Edgecore ECS-2100-52T switches). In such setups,
delegating control to the generic PWM subsystem allows the kernel's
thermal framework to manage the fans based on unrelated temperature
zones, such as internal SoC sensors.

When a PWM consumer applies a new PWM state, the driver automatically
switches the corresponding PWM channel to manual mode so that the
requested duty cycle takes effect. The duty cycle specified by the PWM
framework is internally converted to the 0-255 scale expected by the
hardware registers.

To prevent conflicting access, the hwmon PWM sysfs attributes are hidden
when the device is registered with PWM framework support (i.e. when
"#pwm-cells" is present in DT and CONFIG_PWM is reachable).

Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
Link: https://lore.kernel.org/r/20260805-adt7470_thermalzone-v6-3-5605a5f95467@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

0 files changed, 0 insertions, 0 deletions