• David Brownell's avatar
    i2c: Add i2c_board_info and i2c_new_device() · 9c1600ed
    David Brownell authored
    This provides partial support for new-style I2C driver binding.  It builds
    on "struct i2c_board_info" declarations that identify I2C devices on a given
    board.  This is needed on systems with I2C devices that can't be fully probed
    and/or autoconfigured, such as many embedded Linux configurations where the
    way a given I2C device is wired may affect how it must be used.
    
    There are two models for declaring such devices:
    
     * LATE -- using a public function i2c_new_device().  This lets modules
       declare I2C devices found *AFTER* a given I2C adapter becomes available.
       
       For example, a PCI card could create adapters giving access to utility
       chips on that card, and this would be used to associate those chips with
       those adapters.
    
     * EARLY -- from arch_initcall() level code, using a non-exported function
       i2c_register_board_info().  This copies the declarations *BEFORE* such
       an i2c_adapter becomes available, arranging that i2c_new_device() will
       be called later when i2c-core registers the relevant i2c_adapter.
    
       For example, arch/.../.../board-*.c files would declare the I2C devices
       along with their platform data, and I2C devices would behave much like
       PNPACPI devices.  (That is, both enumerate from board-specific tables.)
    
    To match the exported i2c_new_device(), the previously-private function
    i2c_unregister_device() is now exported.
    
    Pending later patches using these new APIs, this is effectively a NOP.
    Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
    Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
    9c1600ed
i2c-core.c 36.5 KB