dm: implement a MTD uclass

Implement a Memory Technology Device (MTD) uclass. It should
include most flash drivers in the future. Though no uclass ops
are defined yet, the MTD ops could be used.

The NAND flash driver is based on MTD. The CFI flash and SPI
flash support MTD, too. It should make sense to convert them
to MTD uclass.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>

drivers/mtd/Kconfig

@@ -1,3 +1,15 @@
+menu "MTD Support"
+
+config MTD
+	bool "Enable Driver Model for MTD drivers"
+	depends on DM
+	help
+	  Enable driver model for Memory Technology Devices (MTD), such as
+	  flash, RAM and similar chips, often used for solid state file
+	  systems on embedded devices.
+
+endmenu
+
 source "drivers/mtd/nand/Kconfig"
 
 source "drivers/mtd/spi/Kconfig"

drivers/mtd/Makefile

@@ -8,6 +8,7 @@
 ifneq (,$(findstring y,$(CONFIG_MTD_DEVICE)$(CONFIG_CMD_NAND)$(CONFIG_CMD_ONENAND)$(CONFIG_CMD_SF)))
 obj-y += mtdcore.o mtd_uboot.o
 endif
+obj-$(CONFIG_MTD) += mtd-uclass.o
 obj-$(CONFIG_MTD_PARTITIONS) += mtdpart.o
 obj-$(CONFIG_MTD_CONCAT) += mtdconcat.o
 obj-$(CONFIG_HAS_DATAFLASH) += at45.o

drivers/mtd/mtd-uclass.c

@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2015 Thomas Chou <thomas@wytron.com.tw>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <mtd.h>
+
+/*
+ * Implement a MTD uclass which should include most flash drivers.
+ * The uclass private is pointed to mtd_info.
+ */
+
+UCLASS_DRIVER(mtd) = {
+	.id		= UCLASS_MTD,
+	.name		= "mtd",
+	.per_device_auto_alloc_size = sizeof(struct mtd_info),
+};