reset: add Tegra186 reset driver

In Tegra186, on-SoC reset signals are manipulated using IPC requests to
the BPMP (Boot and Power Management Processor). This change implements a
driver that does that. It is unconditionally selected by CONFIG_TEGRA186
since virtually any Tegra186 build of U-Boot will need the feature.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>

arch/arm/mach-tegra/Kconfig

@@ -66,10 +66,12 @@ config TEGRA186
 	bool "Tegra186 family"
 	select CLK
 	select DM_MAILBOX
+	select DM_RESET
 	select MISC
 	select TEGRA186_BPMP
 	select TEGRA186_CLOCK
 	select TEGRA186_GPIO
+	select TEGRA186_RESET
 	select TEGRA_ARMV8_COMMON
 	select TEGRA_HSP
 	select TEGRA_IVC

drivers/reset/Kconfig

@@ -20,4 +20,11 @@ config SANDBOX_RESET
 	  simply accepts requests to reset various HW modules without actually
 	  doing anything beyond a little error checking.
 
+config TEGRA186_RESET
+	bool "Enable Tegra186 BPMP-based reset driver"
+	depends on TEGRA186_BPMP
+	help
+	  Enable support for manipulating Tegra's on-SoC reset signals via IPC
+	  requests to the BPMP (Boot and Power Management Processor).
+
 endmenu

drivers/reset/Makefile

@@ -5,3 +5,4 @@
 obj-$(CONFIG_DM_RESET) += reset-uclass.o
 obj-$(CONFIG_SANDBOX_MBOX) += sandbox-reset.o
 obj-$(CONFIG_SANDBOX_MBOX) += sandbox-reset-test.o
+obj-$(CONFIG_TEGRA186_RESET) += tegra186-reset.o

drivers/reset/tegra186-reset.c

@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2016, NVIDIA CORPORATION.
+ *
+ * SPDX-License-Identifier: GPL-2.0
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <misc.h>
+#include <reset-uclass.h>
+#include <asm/arch-tegra/bpmp_abi.h>
+
+static int tegra186_reset_request(struct reset_ctl *reset_ctl)
+{
+	debug("%s(reset_ctl=%p) (dev=%p, id=%lu)\n", __func__, reset_ctl,
+	      reset_ctl->dev, reset_ctl->id);
+
+	return 0;
+}
+
+static int tegra186_reset_free(struct reset_ctl *reset_ctl)
+{
+	debug("%s(reset_ctl=%p) (dev=%p, id=%lu)\n", __func__, reset_ctl,
+	      reset_ctl->dev, reset_ctl->id);
+
+	return 0;
+}
+
+static int tegra186_reset_common(struct reset_ctl *reset_ctl,
+				 enum mrq_reset_commands cmd)
+{
+	struct mrq_reset_request req;
+	int ret;
+
+	req.cmd = cmd;
+	req.reset_id = reset_ctl->id;
+
+	ret = misc_call(reset_ctl->dev->parent, MRQ_RESET, &req, sizeof(req),
+			NULL, 0);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static int tegra186_reset_assert(struct reset_ctl *reset_ctl)
+{
+	debug("%s(reset_ctl=%p) (dev=%p, id=%lu)\n", __func__, reset_ctl,
+	      reset_ctl->dev, reset_ctl->id);
+
+	return tegra186_reset_common(reset_ctl, CMD_RESET_ASSERT);
+}
+
+static int tegra186_reset_deassert(struct reset_ctl *reset_ctl)
+{
+	debug("%s(reset_ctl=%p) (dev=%p, id=%lu)\n", __func__, reset_ctl,
+	      reset_ctl->dev, reset_ctl->id);
+
+	return tegra186_reset_common(reset_ctl, CMD_RESET_DEASSERT);
+}
+
+struct reset_ops tegra186_reset_ops = {
+	.request = tegra186_reset_request,
+	.free = tegra186_reset_free,
+	.rst_assert = tegra186_reset_assert,
+	.rst_deassert = tegra186_reset_deassert,
+};
+
+static int tegra186_reset_probe(struct udevice *dev)
+{
+	debug("%s(dev=%p)\n", __func__, dev);
+
+	return 0;
+}
+
+U_BOOT_DRIVER(tegra186_reset) = {
+	.name		= "tegra186_reset",
+	.id		= UCLASS_RESET,
+	.probe		= tegra186_reset_probe,
+	.ops = &tegra186_reset_ops,
+};