sandbox: Add PCI driver and test for p2sb

Add a sandbox driver and PCI-device emulator for p2sb. Also add a test
which uses a simple 'adder' driver to test the p2sb functionality.

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

drivers/misc/sandbox_adder.c

@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Sandbox adder for p2sb testing
+ *
+ * Copyright 2019 Google LLC
+ */
+
+#define LOG_CATEGORY UCLASS_MISC
+
+#include <common.h>
+#include <axi.h>
+#include <dm.h>
+#include <misc.h>
+#include <p2sb.h>
+#include <asm/io.h>
+
+struct sandbox_adder_priv {
+	ulong base;
+};
+
+int sandbox_adder_read(struct udevice *dev, ulong address, void *data,
+		       enum axi_size_t size)
+{
+	struct p2sb_child_platdata *pplat = dev_get_parent_platdata(dev);
+	u32 *val = data;
+
+	*val = pplat->pid << 24 | address;
+
+	return 0;
+}
+
+int sandbox_adder_write(struct udevice *dev, ulong address, void *data,
+			enum axi_size_t size)
+{
+	return 0;
+}
+
+static int sandbox_adder_probe(struct udevice *dev)
+{
+	return 0;
+}
+
+static struct axi_ops sandbox_adder_ops = {
+	.read	= sandbox_adder_read,
+	.write	= sandbox_adder_write,
+};
+
+static const struct udevice_id sandbox_adder_ids[] = {
+	{ .compatible = "sandbox,adder" },
+	{ }
+};
+
+U_BOOT_DRIVER(adder_sandbox) = {
+	.name = "sandbox_adder",
+	.id = UCLASS_AXI,
+	.of_match = sandbox_adder_ids,
+	.probe = sandbox_adder_probe,
+	.ops = &sandbox_adder_ops,
+	.priv_auto_alloc_size = sizeof(struct sandbox_adder_priv),
+};