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This is a driver for the MMC controller on the AP7000 chips from Atmel. It should in theory work on AT91 systems too with some tweaking, but since the DMA interface is quite different, it's not entirely clear if it's worth merging this with the at91_mci driver. This driver has been around for a while in BSPs and kernel sources provided by Atmel, but this particular version uses the generic DMA Engine framework (with the slave extensions) instead of an avr32-only DMA controller framework. This driver can also use PIO transfers when no DMA channels are available, and for transfers where using DMA may be difficult or impractical for some reason (e.g. the DMA setup overhead is usually not worth it for very short transfers, and badly aligned buffers or lengths are difficult to handle.) Currently, the driver only support PIO transfers. DMA support has been split out to a separate patch to hopefully make it easier to review. The driver has been tested using mmc-block and ext3fs on several SD, SDHC and MMC+ cards. Reads and writes work fine, with read transfer rates up to 3.5 MiB/s on fast cards with debugging disabled. The driver has also been tested using the mmc_test module on the same cards. All tests except 7, 9, 15 and 17 succeed. The first two are unsupported by all the cards I have, so I don't know if the driver handles this correctly. The last two fail because the hardware flags a Data CRC Error instead of a Data Timeout error. I'm not sure how to deal with that. Documentation for this controller can be found in many data sheets from Atmel, including the AT32AP7000 data sheet which can be found here: http://www.atmel.com/dyn/products/datasheets.asp?family_id=682 Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com> Signed-off-by: Pierre Ossman <drzeus@drzeus.cx> |
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