ahci: Add a disk-controller uclass

Add a uclass ID for a disk controller. This can be used by AHCI/SATA or
other controller types. There are no operations and no interface so far,
but it is possible to probe a SATA device.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

drivers/block/Kconfig

@@ -0,0 +1,9 @@
+config DISK
+	bool "Support disk controllers with driver model"
+	depends on DM
+	default y if DM
+	help
+	  This enables a uclass for disk controllers in U-Boot. Various driver
+	  types can use this, such as AHCI/SATA. It does not provide any standard
+	  operations at present. The block device interface has not been converted
+	  to driver model.

drivers/block/Makefile

@@ -5,6 +5,7 @@
 # SPDX-License-Identifier:	GPL-2.0+
 #
 
+obj-$(CONFIG_DISK) += disk-uclass.o
 obj-$(CONFIG_SCSI_AHCI) += ahci.o
 obj-$(CONFIG_DWC_AHSATA) += dwc_ahsata.o
 obj-$(CONFIG_FSL_SATA) += fsl_sata.o

drivers/block/disk-uclass.c

@@ -0,0 +1,14 @@
+/*
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+
+UCLASS_DRIVER(disk) = {
+	.id		= UCLASS_DISK,
+	.name		= "disk",
+};

include/dm/uclass-id.h

@@ -29,6 +29,7 @@ enum uclass_id {
 	UCLASS_CLK,		/* Clock source, e.g. used by peripherals */
 	UCLASS_CPU,		/* CPU, typically part of an SoC */
 	UCLASS_CROS_EC,		/* Chrome OS EC */
+	UCLASS_DISK,		/* Disk controller, e.g. SATA */
 	UCLASS_DISPLAY,		/* Display (e.g. DisplayPort, HDMI) */
 	UCLASS_RAM,		/* RAM controller */
 	UCLASS_ETH,		/* Ethernet device */