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>

include/dm/uclass-id.h

@@ -36,6 +36,7 @@ enum uclass_id {
 	UCLASS_LED,		/* Light-emitting diode (LED) */
 	UCLASS_LPC,		/* x86 'low pin count' interface */
 	UCLASS_MASS_STORAGE,	/* Mass storage device */
+	UCLASS_MMC,		/* SD / MMC card or chip */
 	UCLASS_MOD_EXP,		/* RSA Mod Exp device */
 	UCLASS_PCH,		/* x86 platform controller hub */
 	UCLASS_PCI,		/* PCI bus */

include/mmc.h

@@ -266,6 +266,28 @@
 #define MMC_NUM_BOOT_PARTITION	2
 #define MMC_PART_RPMB           3       /* RPMB partition number */
 
+/* Driver model support */
+
+/**
+ * struct mmc_uclass_priv - Holds information about a device used by the uclass
+ */
+struct mmc_uclass_priv {
+	struct mmc *mmc;
+};
+
+/**
+ * mmc_get_mmc_dev() - get the MMC struct pointer for a device
+ *
+ * Provided that the device is already probed and ready for use, this value
+ * will be available.
+ *
+ * @dev:	Device
+ * @return associated mmc struct pointer if available, else NULL
+ */
+struct mmc *mmc_get_mmc_dev(struct udevice *dev);
+
+/* End of driver model support */
+
 struct mmc_cid {
 	unsigned long psn;
 	unsigned short oid;