reset: implement a reset test

This adds a sandbox reset implementation (provider), a test client
device, instantiates them both from Sandbox's DT, and adds a DM test
that excercises everything.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/reset/sandbox-reset.c b/drivers/reset/sandbox-reset.c
new file mode 100644
index 0000000..4258af5
--- /dev/null
+++ b/drivers/reset/sandbox-reset.c
@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2016, NVIDIA CORPORATION.
+ *
+ * SPDX-License-Identifier: GPL-2.0
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <reset-uclass.h>
+#include <asm/io.h>
+#include <asm/reset.h>
+
+#define SANDBOX_RESET_SIGNALS 3
+
+struct sandbox_reset_signal {
+	bool asserted;
+};
+
+struct sandbox_reset {
+	struct sandbox_reset_signal signals[SANDBOX_RESET_SIGNALS];
+};
+
+static int sandbox_reset_request(struct reset_ctl *reset_ctl)
+{
+	debug("%s(reset_ctl=%p)\n", __func__, reset_ctl);
+
+	if (reset_ctl->id >= SANDBOX_RESET_SIGNALS)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int sandbox_reset_free(struct reset_ctl *reset_ctl)
+{
+	debug("%s(reset_ctl=%p)\n", __func__, reset_ctl);
+
+	return 0;
+}
+
+static int sandbox_reset_assert(struct reset_ctl *reset_ctl)
+{
+	struct sandbox_reset *sbr = dev_get_priv(reset_ctl->dev);
+
+	debug("%s(reset_ctl=%p)\n", __func__, reset_ctl);
+
+	sbr->signals[reset_ctl->id].asserted = true;
+
+	return 0;
+}
+
+static int sandbox_reset_deassert(struct reset_ctl *reset_ctl)
+{
+	struct sandbox_reset *sbr = dev_get_priv(reset_ctl->dev);
+
+	debug("%s(reset_ctl=%p)\n", __func__, reset_ctl);
+
+	sbr->signals[reset_ctl->id].asserted = false;
+
+	return 0;
+}
+
+static int sandbox_reset_bind(struct udevice *dev)
+{
+	debug("%s(dev=%p)\n", __func__, dev);
+
+	return 0;
+}
+
+static int sandbox_reset_probe(struct udevice *dev)
+{
+	debug("%s(dev=%p)\n", __func__, dev);
+
+	return 0;
+}
+
+static const struct udevice_id sandbox_reset_ids[] = {
+	{ .compatible = "sandbox,reset-ctl" },
+	{ }
+};
+
+struct reset_ops sandbox_reset_reset_ops = {
+	.request = sandbox_reset_request,
+	.free = sandbox_reset_free,
+	.rst_assert = sandbox_reset_assert,
+	.rst_deassert = sandbox_reset_deassert,
+};
+
+U_BOOT_DRIVER(sandbox_reset) = {
+	.name = "sandbox_reset",
+	.id = UCLASS_RESET,
+	.of_match = sandbox_reset_ids,
+	.bind = sandbox_reset_bind,
+	.probe = sandbox_reset_probe,
+	.priv_auto_alloc_size = sizeof(struct sandbox_reset),
+	.ops = &sandbox_reset_reset_ops,
+};
+
+int sandbox_reset_query(struct udevice *dev, unsigned long id)
+{
+	struct sandbox_reset *sbr = dev_get_priv(dev);
+
+	debug("%s(dev=%p, id=%ld)\n", __func__, dev, id);
+
+	if (id >= SANDBOX_RESET_SIGNALS)
+		return -EINVAL;
+
+	return sbr->signals[id].asserted;
+}