/*
* MMCIF eMMC driver.
*
* Copyright (C) 2010 Renesas Solutions Corp.
* Yusuke Goda <yusuke.goda.sx@renesas.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License.
*
*
* TODO
* 1. DMA
* 2. Power management
* 3. Handle MMC errors better
*
*/
/*
* The MMCIF driver is now processing MMC requests asynchronously, according
* to the Linux MMC API requirement.
*
* The MMCIF driver processes MMC requests in up to 3 stages: command, optional
* data, and optional stop. To achieve asynchronous processing each of these
* stages is split into two halves: a top and a bottom half. The top half
* initialises the hardware, installs a timeout handler to handle completion
* timeouts, and returns. In case of the command stage this immediately returns
* control to the caller, leaving all further processing to run asynchronously.
* All further request processing is performed by the bottom halves.
*
* The bottom half further consists of a "hard" IRQ handler, an IRQ handler
* thread, a DMA completion callback, if DMA is used, a timeout work, and
* request- and stage-specific handler methods.
*
* Each bottom half run begins with either a hardware interrupt, a DMA callback
