DMIC IO Driver

@startuml hide methods hide attributes component Zephyr { class DmicDriver interface dai_dmic_ops interface dai_driver_api } component MPP { interface Gateway interface IoDriver class DmicManager class DmicInput } DmicDriver -up- dai_dmic_ops dai_dmic_ops -left-|> dai_driver_api : implements DmicManager -up- IoDriver DmicManager -left-> DmicInput : manages DmicInput -up- Gateway DmicInput -down-> dai_dmic_ops : calls DmicDriver --* DmicInput @enduml

Figure 80 DMIC IO Driver overview

Gateway Initialization

@startuml participant "DMIC Manager" as dmic_manager participant "Zephyr PM Subsystem" as zephyr_pm participant "DMIC Driver" as dmic_driver -> dmic_manager : gateway_allocate() activate dmic_manager dmic_manager -> zephyr_pm : pm_runtime_device_get (dmic) activate zephyr_pm zephyr_pm -> zephyr_pm : increase usage count opt if usage == 1 zephyr_pm -> dmic_driver : pm_device_resume activate dmic_driver return end return deactivate dmic_manager <-- dmic_manager @enduml

Figure 81 DMIC Input Gateway Initialization

DMIC HW is initialized as follows:

  1. Mute microphones.

  2. Enable clock on microphones (also enable CIC and FIRs).

  3. Wait for clock stabilization (SoC defined delay).

  4. Unmute microphones using a curved ramp until the DC offset is gone and replaced with the live stream.

Configuration BLOB

DMIC IO Driver is prepared for the configuration BLOB to come in context of any instance of the DmicInput at any time. The configuration may be rejected if the current state of PDM controllers and FIFOs is inappropriate. Accepting the configuration does not always mean that it is immediately programmed to the HW. The configuration is global, so when sent by an instance of DmicInput while another instance is already running it is just compared with already programmed data for the sake of consistency.

Gateway Release

@startuml participant "DMIC Manager" as dmic_manager participant "Zephyr PM Subsystem" as zephyr_pm participant "DMIC Driver" as dmic_driver -> dmic_manager : gateway_release() activate dmic_manager dmic_manager -> zephyr_pm : pm_runtime_device_put (dmic) activate zephyr_pm zephyr_pm -> zephyr_pm : decrease usage count opt if usage == 0 zephyr_pm -> dmic_driver : pm_device_suspend activate dmic_driver return end return deactivate dmic_manager <-- dmic_manager @enduml

Figure 82 DMIC Input Gateway Release

State Transitions

participant "Dmic Input\nGateway" as dmic_input participant "DMA" as dma == Dmic Input : STOPPED == -> dmic_input : STOPPED dmic_input -> dma : stop() == Dmic Input : PAUSED == -> dmic_input : PAUSED dmic_input -> dma : init_transfer() dmic_input -> dma : pause() == Dmic Input : RUNNING == -> dmic_input : RUNNING dmic_input -> dma : start()

Figure 83 DMIC Input Gateway State Transition