[U-Boot] [PATCH v3 0/4] mmc: Implement central card-detection.

[Mike Frysinger <vapier@gentoo.org>]

On Tuesday 20 December 2011 03:52:39 Thierry Reding wrote:
> This series of patches implements central card-detection within the MMC
> framework. Before this patch series, many boards actually did implement
> the board_mmc_getcd() function, but it wasn't used except by one driver
> (fsl_esdhc). Unfortunately, implementations interpreted the meaning of
> the cd parameter differently, some taking it to signal card absence and
> others using it to detect card presence. Furthermore, the signature of
> the board_mmc_getcd() function was not at all consistent with other MMC
> related functions.

as you've seen, GPIO pin detection is not novel or unique to any driver/SoC.  
i'd suggest instead finding a way to move this into "struct mmc".  perhaps 
something like:

include/mmc.h:
struct mmc {
	...
#ifdef CONFIG_MMC_GPIO_CD
	unsigned gpio_cd;
#endif
	...
};

and then the default mmc_register() func can do:
#ifdef CONFIG_MMC_GPIO_CD
	if (!mmc->getcd)
		mmc->getcd = mmc_getcd_gpio;
#endif

and we can have the drivers/mmc/mmc.c:
#ifdef CONFIG_MMC_GPIO_CD
int mmc_getcd_gpio(struct mmc *mmc)
{
	return !gpio_get_value(mmc->getcd);
}
#endif

then mmc drivers can extend their register function to take a GPIO number (if 
they don't already).  and then they get everything else for free.
-mike
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