• Hema HK's avatar
    usb: musb: Idle path retention and offmode support for OMAP3 · 7acc6197
    Hema HK authored
    This patch supports the retention and offmode support in the idle path for
    musb driver using runtime pm APIs.
    
    This is restricted to support offmode and retention only when device not
    connected.When device/cable connected with gadget driver loaded,configured
    to no idle/standby which will not allow the core transition to retention
    or off.
    
    There is no context save/restore done by hardware for musb in OMAP3
    and OMAP4,driver has to take care of saving and restoring the context
    during offmode.
    
    Musb has a requirement of configuring sysconfig register to force
    idle/standby mode and set the ENFORCE bit in module STANDBY register
    for retention and offmode support.
    
    Runtime pm and hwmod frameworks will take care of configuring to force
    idle/standby when pm_runtime_put_sync is called and back to no
    idle/standby when pm_runeime_get_sync is called.
    
    Compile, boot tested and also tested the retention in the idle path on
    OMAP3630Zoom3. And tested the global suspend/resume with offmode enabled.
    Usb basic functionality tested on OMAP4430SDP.
    
    There is some problem with idle path offmode in mainline, I could not test
    with offmode. But I have tested this patch with resetting the controller
    in the idle path when wakeup from retention just to make sure that the
    context is lost, and restore path is working fine.
    
    Removed .suspend/.resume fnction pointers and functions because there
    is no need of having these functions as all required work is done
    at runtime in the driver.
    
    There is no need to call the runtime pm api with glue driver device
    as glue layer device is the parent of musb core device, when runtime apis
    are called for the child, parent device runtime functionality
    will be invoked.
    
    Design overview:
    
    pm_runtime_get_sync: When called with musb core device takes care of
    enabling the clock, calling runtime callback function of omap2430 glue
    layer, runtime call back of musb driver and configure the musb sysconfig
    to no idle/standby
    
    pm_runtime_put: Takes care of calling runtime callback function of omap2430
    glue layer, runtime call back of musb driver, Configure the musb sysconfig
    to force idle/standby and disable the clock.
    
    During musb driver load: Call pm_runtime_get_sync.
    
    End of musb driver load: Call pm_runtime_put
    
    During gadget driver load: Call pm_runtime_get_sync,
    End of gadget driver load: Call pm_runtime_put if there is no device
    or cable is connected.
    
    During unload of the gadget driver:Call pm_runtime_get_sync if cable/device
    is not connected.
    End of the gadget driver unload : pm_runtime_put
    
    During unload of musb driver : Call pm_runtime_get_sync
    End of unload: Call pm_runtime_put
    
    On connect of usb cable/device -> transceiver notification(VBUS and ID-GND):
    pm_runtime_get_sync only if the gadget driver loaded.
    
    On disconnect of the cable/device -> Disconnect Notification:
    pm_runtime_put if the gadget driver is loaded.
    Signed-off-by: default avatarHema HK <hemahk@ti.com>
    Signed-off-by: default avatarFelipe Balbi <balbi@ti.com>
    7acc6197
musb_core.c 67.8 KB