sysreset: Add TI System Control Interface (TI SCI) sysreset driver

Devices from the TI K3 family of SoCs like the AM654x contain a Device
Management and Security Controller (SYSFW) that manages the low-level
device control (like clocks, resets etc) for the various hardware
modules present on the SoC. These device control operations are provided
to the host processor OS through a communication protocol called the TI
System Control Interface (TI SCI) protocol.

This patch adds a system reset driver that communicates to the system
controller over the TI SCI protocol for allowing to perform a system-
wide SoC reset.

Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Andreas Dannenberg <dannenberg@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>

doc/device-tree-bindings/sysreset/ti,sci-sysreset.txt

@@ -0,0 +1,29 @@
+Texas Instruments TI SCI System Reset Controller
+================================================
+
+Some TI SoCs contain a system controller (like the SYSFW, etc...) that is
+responsible for controlling the state of the IPs that are present.
+Communication between the host processor running an OS and the system
+controller happens through a protocol known as TI SCI [1].
+
+[1] http://processors.wiki.ti.com/index.php/TISCI
+
+System Reset Controller Node
+============================
+The sysreset controller node represents the reset for the overall SoC
+which is managed by the SYSFW. Because this relies on the TI SCI protocol
+to communicate with the SYSFW it must be a child of the sysfw node.
+
+Required Properties:
+--------------------
+ - compatible: Must be "ti,sci-sysreset"
+
+Example (AM65x):
+----------------
+	sysfw: sysfw {
+		compatible = "ti,am654-system-controller";
+		...
+		k3_sysreset: sysreset-controller {
+			compatible = "ti,sci-sysreset";
+		};
+	};

drivers/sysreset/Kconfig

@@ -36,6 +36,13 @@ config SYSRESET_PSCI
 	  Enable PSCI SYSTEM_RESET function call.  To use this, PSCI firmware
 	  must be running on your system.
 
+config SYSRESET_TI_SCI
+	bool "TI System Control Interface (TI SCI) system reset driver"
+	depends on TI_SCI_PROTOCOL
+	help
+	  This enables the system reset driver support over TI System Control
+	  Interface available on some new TI's SoCs.
+
 endif
 
 config SYSRESET_SYSCON

drivers/sysreset/Makefile

@@ -6,6 +6,7 @@ obj-$(CONFIG_SYSRESET) += sysreset-uclass.o
 obj-$(CONFIG_SYSRESET_GPIO) += sysreset_gpio.o
 obj-$(CONFIG_SYSRESET_MICROBLAZE) += sysreset_microblaze.o
 obj-$(CONFIG_SYSRESET_PSCI) += sysreset_psci.o
+obj-$(CONFIG_SYSRESET_TI_SCI) += sysreset-ti-sci.o
 obj-$(CONFIG_SYSRESET_SYSCON) += sysreset_syscon.o
 obj-$(CONFIG_SYSRESET_WATCHDOG) += sysreset_watchdog.o
 obj-$(CONFIG_SYSRESET_X86) += sysreset_x86.o

drivers/sysreset/sysreset-ti-sci.c

@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Texas Instruments System Control Interface (TI SCI) system reset driver
+ *
+ * Copyright (C) 2018 Texas Instruments Incorporated - http://www.ti.com/
+ *	Andreas Dannenberg <dannenberg@ti.com>
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <sysreset.h>
+#include <linux/soc/ti/ti_sci_protocol.h>
+
+/**
+ * struct ti_sci_sysreset_data - sysreset controller information structure
+ * @sci: TI SCI handle used for communication with system controller
+ */
+struct ti_sci_sysreset_data {
+	const struct ti_sci_handle *sci;
+};
+
+static int ti_sci_sysreset_probe(struct udevice *dev)
+{
+	struct ti_sci_sysreset_data *data = dev_get_priv(dev);
+
+	debug("%s(dev=%p)\n", __func__, dev);
+
+	if (!data)
+		return -ENOMEM;
+
+	/* Store handle for communication with the system controller */
+	data->sci = ti_sci_get_handle(dev);
+	if (IS_ERR(data->sci))
+		return PTR_ERR(data->sci);
+
+	return 0;
+}
+
+static int ti_sci_sysreset_request(struct udevice *dev, enum sysreset_t type)
+{
+	struct ti_sci_sysreset_data *data = dev_get_priv(dev);
+	const struct ti_sci_handle *sci = data->sci;
+	const struct ti_sci_core_ops *cops = &sci->ops.core_ops;
+	int ret;
+
+	debug("%s(dev=%p, type=%d)\n", __func__, dev, type);
+
+	ret = cops->reboot_device(sci);
+	if (ret)
+		dev_err(rst->dev, "%s: reboot_device failed (%d)\n",
+			__func__, ret);
+
+	return ret;
+}
+
+static struct sysreset_ops ti_sci_sysreset_ops = {
+	.request = ti_sci_sysreset_request,
+};
+
+static const struct udevice_id ti_sci_sysreset_of_match[] = {
+	{ .compatible = "ti,sci-sysreset", },
+	{ /* sentinel */ },
+};
+
+U_BOOT_DRIVER(ti_sci_sysreset) = {
+	.name = "ti-sci-sysreset",
+	.id = UCLASS_SYSRESET,
+	.of_match = ti_sci_sysreset_of_match,
+	.probe = ti_sci_sysreset_probe,
+	.priv_auto_alloc_size = sizeof(struct ti_sci_sysreset_data),
+	.ops = &ti_sci_sysreset_ops,
+};