dm: mmc: Add an MMC uclass

Add basic support for MMC, providing a uclass which can set up an MMC
device. This allows MMC drivers to move to using driver model.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/mmc/Kconfig b/drivers/mmc/Kconfig
index 7ba85a2..3e835f7 100644
--- a/drivers/mmc/Kconfig
+++ b/drivers/mmc/Kconfig
@@ -1,5 +1,15 @@
 menu "MMC Host controller Support"
 
+config DM_MMC
+	bool "Enable MMC controllers using Driver Model"
+	depends on DM
+	help
+	  This enables the MultiMediaCard (MMC) uclass which suports MMC and
+	  Secure Digital I/O (SDIO) cards. Both removable (SD, micro-SD, etc.)
+	  and non-removable (e.g. eMMC chip) devices are supported. These
+	  appear as block devices in U-Boot and can support filesystems such
+	  as EXT4 and FAT.
+
 config SH_SDHI
 	bool "SuperH/Renesas ARM SoCs on-chip SDHI host controller support"
 	depends on RMOBILE