57 lines
2.3 KiB
Text
57 lines
2.3 KiB
Text
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This directory contains code to access MMC based devices.
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It was created during the initial port of MINIX to the ARM platform. mmbclk
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implements a normal MINIX block device. It uses the interfaces defined in
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mmchost.h to perform it's operations.
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mmchost_mmchs is the MMC host controller driver for the TI omap device range.
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It contains the logic to access SD cards on that device.
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drivers/mmc
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|-- Makefile (The makefile)
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|-- mmclog.h (A simpel logging system)
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|-- omap_mmc.h (TI Omap register definitions)
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|-- sdhcreg.h (BSD headers for the MMC layer)
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|-- sdmmcreg.h (BSD headers for the MMC layer)
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|-- mmcblk.c (MINIX 3 block device)
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|-- mmchost.h (interface between the block device and the MMC layer)
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|-- mmchost_mmchs.c (Driver to use on the ARM port/beagle)
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'-- README.txt (This file)
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Future work:
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============
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* Creating a more generic MMC layer
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The SD protocol is well defined and the imported the netbsd sdhcreg and
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sdmmcreg headers will allow us to make the MMC interface more generic. We would
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like mmchost_mmchs to be split in a generic part and a specific part.
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* Using interrupts
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At time of writing the interrupt handlers on the ARM port are not implemented.
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Once that is done we will be able to rewrite the code to use proper interrupt
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handlers.
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* 4 and 8 bits access
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The driver currently only reads data over a single data line. Adding support
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for 4 or 8 bits(for movinands) mode is very welcome.
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* DMA.
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The OMAP driver allows the usage of DMA. Adding DMA support will increase the
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performance of the driver
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* Removal of the PRIVCTL call.
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The MMC driver uses memory mapped IO to perform it's operations. On i386 it is
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the pci driver that will grant access to certain piece of memory to a driver.
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On the ARM port we lack pci and other self describing busses. In the current
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driver the driver will itself grant itself access to the correct piece of
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memory but this is unwanted behavior. We currently as thinking about two
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possible solutions. The first would be to add the memory ranges in system.conf.
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The second would be to modify the PCI driver to grant access to memory based on
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a fixed configuration. For example we could use the driver tree to perform
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device discovery and granting access to devices.
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* TODO removal
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The driver contains (quite a few) TODO's where the code need to be improved.
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