doc/driver-model/UDM-pcmcia.txt

The U-Boot Driver Model Project
===============================
PCMCIA analysis
===============
Viktor Krivak <viktor.krivak@gmail.com>
2012-03-17

I) Overview
-----------

  U-boot implements only 2 methods to interoperate with pcmcia. One to turn
  device on and other to turn device off. Names of these methods are usually
  pcmcia_on() and pcmcia_off() without any parameters. Some files in driver
  directory implements only internal API. These methods aren't used outside
  driver directory and they are not converted to new driver model.

II) Approach
-----------

  1) New API
  ----------

    Current API is preserved and all internal methods are hiden.

    struct ops {
      void (*pcmcia_on)(struct instance *i);
      void (*pcmcia_off)(struct instance *i);
    }

  2) Conversion
  -------------

    In header file pcmcia.h are some other variables which are used for
    additional configuration. But all have to be moved to platform data or to
    specific driver implementation.

  3) Platform data
  ----------------

    Many boards have custom implementation of internal API. Pointers to these
    methods are stored in platform_data. But the most implementations for Intel
    82365 and compatible PC Card controllers and Yenta-compatible
    PCI-to-CardBus controllers implement whole API per board. In these cases
    pcmcia_on() and pcmcia_off() behave only as wrappers and call specific
    board methods.

III) Analysis of in-tree drivers
--------------------------------

  1) i82365.c
  -----------
    Driver methods have different name i82365_init() and i82365_exit but
    all functionality is the same. Board files board/atc/ti113x.c and
    board/cpc45/pd67290.c use their own implementation of these method.
    In this case all methods in driver behave only as wrappers.

  2) marubun_pcmcia.c
  -------------------
    Meets standard API behaviour. Simple conversion.

  3) mpc8xx_pcmcia.c
  ------------------
    Meets standard API behaviour. Simple conversion.

  4) rpx_pcmcia.c
  ---------------
    Implements only internal API used in other drivers. Non of methods
    implemented here are used outside driver model.

  5) ti_pci1410a.c
  ----------------
    Has different API but methods in this file are never called. Probably
    dead code.

  6)tqm8xx_pcmcia.c
  -----------------
    Implements only internal API used in other drivers. Non of methods
    implemented here are used outside driver model.