mmc: host: add Coldfire esdhc support

This driver has been developed as a separate module starting
from the similar sdhci-esdhc-imx.c.

Reasons for a separate sdchi-esdhc-mcf driver:

- m68K architecture does not support devicetrees, so modifying
sdhci-of-esdhc.c that is devicetree-related adding platform data
seems not appropriate,
- clock-related part, has to be implemented specifically for
mcf5441x family (see esdhc_mcf_pltfm_set_clock()),
- this is a big endian cpu accessing a big endian controller,
but about sdma, this controller does not support hw swap, which
needs to be handled with specific code,
- some other minor differences but mainly to avoid risks on
tweaking inside largely used imx driver. Adding just a small
size ColdFire-specific driver, with benefits in a further less
risky maintenance.
Signed-off-by: Angelo Dureghello <angelo.dureghello@timesys.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20200518191742.1251440-3-angelo.dureghello@timesys.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/Kconfig

@@ -235,6 +235,19 @@ config MMC_SDHCI_CNS3XXX
 
 	  If unsure, say N.
 
+config MMC_SDHCI_ESDHC_MCF
+	tristate "SDHCI support for the Freescale eSDHC ColdFire controller"
+	depends on M5441x
+	depends on MMC_SDHCI_PLTFM
+	select MMC_SDHCI_IO_ACCESSORS
+	help
+	  This selects the Freescale eSDHC controller support for
+	  ColdFire mcf5441x devices.
+
+	  If you have a controller with this interface, say Y or M here.
+
+	  If unsure, say N.
+
 config MMC_SDHCI_ESDHC_IMX
 	tristate "SDHCI support for the Freescale eSDHC/uSDHC i.MX controller"
 	depends on ARCH_MXC

drivers/mmc/host/Makefile

@@ -84,6 +84,7 @@ obj-$(CONFIG_MMC_REALTEK_USB)	+= rtsx_usb_sdmmc.o
 obj-$(CONFIG_MMC_SDHCI_PLTFM)		+= sdhci-pltfm.o
 obj-$(CONFIG_MMC_SDHCI_CADENCE)		+= sdhci-cadence.o
 obj-$(CONFIG_MMC_SDHCI_CNS3XXX)		+= sdhci-cns3xxx.o
+obj-$(CONFIG_MMC_SDHCI_ESDHC_MCF)       += sdhci-esdhc-mcf.o
 obj-$(CONFIG_MMC_SDHCI_ESDHC_IMX)	+= sdhci-esdhc-imx.o
 obj-$(CONFIG_MMC_SDHCI_DOVE)		+= sdhci-dove.o
 obj-$(CONFIG_MMC_SDHCI_TEGRA)		+= sdhci-tegra.o