dm: x86: Add a uclass for an Low Pin Count (LPC) device

On x86 systems this device is commonly used to provide legacy port access.
It is sort-of a replacement for the old ISA bus.

Add a uclass for this, and allow it to have child devices.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/x86/lib/Makefile

@@ -14,6 +14,7 @@ obj-$(CONFIG_HAVE_FSP) += cmd_hob.o
 obj-y	+= gcc.o
 obj-y	+= init_helpers.o
 obj-y	+= interrupts.o
+obj-y	+= lpc-uclass.o
 obj-y += cmd_mtrr.o
 obj-$(CONFIG_SYS_PCAT_INTERRUPTS) += pcat_interrupts.o
 obj-$(CONFIG_SYS_PCAT_TIMER) += pcat_timer.o

arch/x86/lib/lpc-uclass.c

+/*
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <dm/root.h>
+
+static int lpc_uclass_post_bind(struct udevice *bus)
+{
+	/*
+	 * Scan the device tree for devices
+	 *
+	 * Before relocation, only bind devices marked for pre-relocation
+	 * use.
+	 */
+	return dm_scan_fdt_node(bus, gd->fdt_blob, bus->of_offset,
+				gd->flags & GD_FLG_RELOC ? false : true);
+}
+
+UCLASS_DRIVER(lpc) = {
+	.id		= UCLASS_LPC,
+	.name		= "lpc",
+	.post_bind	= lpc_uclass_post_bind,
+};

include/dm/uclass-id.h

@@ -39,6 +39,7 @@ enum uclass_id {
 	UCLASS_PCI_GENERIC,	/* Generic PCI bus device */
 	UCLASS_PCH,		/* x86 platform controller hub */
 	UCLASS_ETH,		/* Ethernet device */
+	UCLASS_LPC,		/* x86 'low pin count' interface */
 
 	UCLASS_COUNT,
 	UCLASS_INVALID = -1,