• Heikki Krogerus's avatar
    usb: add bus type for USB ULPI · 289fcff4
    Heikki Krogerus authored
    UTMI+ Low Pin Interface (ULPI) is a commonly used PHY
    interface for USB 2.0. The ULPI specification describes a
    standard set of registers which the vendors can extend for
    their specific needs. ULPI PHYs provide often functions
    such as charger detection and ADP sensing and probing.
    
    There are two major issues that the bus type is meant to
    tackle:
    
    Firstly, ULPI registers are accessed from the controller.
    The bus provides convenient method for the controller
    drivers to share that access with the actual PHY drivers.
    
    Secondly, there are already platforms that assume ULPI PHYs
    are runtime detected, such as many Intel Baytrail based
    platforms. They do not provide any kind of hardware
    description for the ULPI PHYs like separate ACPI device
    object that could be used to enumerate a device from.
    Signed-off-by: default avatarHeikki Krogerus <heikki.krogerus@linux.intel.com>
    Acked-by: default avatarDavid Cohen <david.a.cohen@linux.intel.com>
    Signed-off-by: default avatarFelipe Balbi <balbi@ti.com>
    289fcff4
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