firmware: arm_sdei: Add driver for Software Delegated Exceptions

The Software Delegated Exception Interface (SDEI) is an ARM standard
for registering callbacks from the platform firmware into the OS.
This is typically used to implement firmware notifications (such as
firmware-first RAS) or promote an IRQ that has been promoted to a
firmware-assisted NMI.

Add the code for detecting the SDEI version and the framework for
registering and unregistering events. Subsequent patches will add the
arch-specific backend code and the necessary power management hooks.

Only shared events are supported, power management, private events and
discovery for ACPI systems will be added by later patches.
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

MAINTAINERS

@@ -12618,6 +12618,15 @@ L:	linux-media@vger.kernel.org
 S:	Supported
 F:	drivers/media/pci/solo6x10/
 
+SOFTWARE DELEGATED EXCEPTION INTERFACE (SDEI)
+M:	James Morse <james.morse@arm.com>
+L:	linux-arm-kernel@lists.infradead.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/arm/firmware/sdei.txt
+F:	drivers/firmware/arm_sdei.c
+F:	include/linux/sdei.h
+F:	include/uapi/linux/sdei.h
+
 SOFTWARE RAID (Multiple Disks) SUPPORT
 M:	Shaohua Li <shli@kernel.org>
 L:	linux-raid@vger.kernel.org

arch/arm64/include/asm/sdei.h

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2017 Arm Ltd.
+#ifndef __ASM_SDEI_H
+#define __ASM_SDEI_H
+
+/* Later patches add the arch specific bits */
+
+#endif /* __ASM_SDEI_H */

drivers/firmware/Kconfig

@@ -48,6 +48,14 @@ config ARM_SCPI_POWER_DOMAIN
 	  This enables support for the SCPI power domains which can be
 	  enabled or disabled via the SCP firmware
 
+config ARM_SDE_INTERFACE
+	bool "ARM Software Delegated Exception Interface (SDEI)"
+	depends on ARM64
+	help
+	  The Software Delegated Exception Interface (SDEI) is an ARM
+	  standard for registering callbacks from the platform firmware
+	  into the OS. This is typically used to implement RAS notifications.
+
 config EDD
 	tristate "BIOS Enhanced Disk Drive calls determine boot disk"
 	depends on X86

drivers/firmware/Makefile

@@ -6,6 +6,7 @@ obj-$(CONFIG_ARM_PSCI_FW)	+= psci.o
 obj-$(CONFIG_ARM_PSCI_CHECKER)	+= psci_checker.o
 obj-$(CONFIG_ARM_SCPI_PROTOCOL)	+= arm_scpi.o
 obj-$(CONFIG_ARM_SCPI_POWER_DOMAIN) += scpi_pm_domain.o
+obj-$(CONFIG_ARM_SDE_INTERFACE)	+= arm_sdei.o
 obj-$(CONFIG_DMI)		+= dmi_scan.o
 obj-$(CONFIG_DMI_SYSFS)		+= dmi-sysfs.o
 obj-$(CONFIG_EDD)		+= edd.o

include/linux/arm_sdei.h

+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2017 Arm Ltd.
+#ifndef __LINUX_ARM_SDEI_H
+#define __LINUX_ARM_SDEI_H
+
+#include <uapi/linux/arm_sdei.h>
+
+enum sdei_conduit_types {
+	CONDUIT_INVALID = 0,
+	CONDUIT_SMC,
+	CONDUIT_HVC,
+};
+
+#include <asm/sdei.h>
+
+/* Arch code should override this to set the entry point from firmware... */
+#ifndef sdei_arch_get_entry_point
+#define sdei_arch_get_entry_point(conduit)	(0)
+#endif
+
+/*
+ * When an event occurs sdei_event_handler() will call a user-provided callback
+ * like this in NMI context on the CPU that received the event.
+ */
+typedef int (sdei_event_callback)(u32 event, struct pt_regs *regs, void *arg);
+
+/*
+ * Register your callback to claim an event. The event must be described
+ * by firmware.
+ */
+int sdei_event_register(u32 event_num, sdei_event_callback *cb, void *arg);
+
+/*
+ * Calls to sdei_event_unregister() may return EINPROGRESS. Keep calling
+ * it until it succeeds.
+ */
+int sdei_event_unregister(u32 event_num);
+
+int sdei_event_enable(u32 event_num);
+int sdei_event_disable(u32 event_num);
+
+#ifdef CONFIG_ARM_SDE_INTERFACE
+/* For use by arch code when CPU hotplug notifiers are not appropriate. */
+int sdei_mask_local_cpu(void);
+int sdei_unmask_local_cpu(void);
+#else
+static inline int sdei_mask_local_cpu(void) { return 0; }
+static inline int sdei_unmask_local_cpu(void) { return 0; }
+#endif /* CONFIG_ARM_SDE_INTERFACE */
+
+
+/*
+ * This struct represents an event that has been registered. The driver
+ * maintains a list of all events, and which ones are registered. (Private
+ * events have one entry in the list, but are registered on each CPU).
+ * A pointer to this struct is passed to firmware, and back to the event
+ * handler. The event handler can then use this to invoke the registered
+ * callback, without having to walk the list.
+ *
+ * For CPU private events, this structure is per-cpu.
+ */
+struct sdei_registered_event {
+	/* For use by arch code: */
+	struct pt_regs          interrupted_regs;
+
+	sdei_event_callback	*callback;
+	void			*callback_arg;
+	u32			 event_num;
+	u8			 priority;
+};
+
+/* The arch code entry point should then call this when an event arrives. */
+int notrace sdei_event_handler(struct pt_regs *regs,
+			       struct sdei_registered_event *arg);
+
+/* arch code may use this to retrieve the extra registers. */
+int sdei_api_event_context(u32 query, u64 *result);
+
+#endif /* __LINUX_ARM_SDEI_H */

include/uapi/linux/arm_sdei.h

+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/* Copyright (C) 2017 Arm Ltd. */
+#ifndef _UAPI_LINUX_ARM_SDEI_H
+#define _UAPI_LINUX_ARM_SDEI_H
+
+#define SDEI_1_0_FN_BASE			0xC4000020
+#define SDEI_1_0_MASK				0xFFFFFFE0
+#define SDEI_1_0_FN(n)				(SDEI_1_0_FN_BASE + (n))
+
+#define SDEI_1_0_FN_SDEI_VERSION			SDEI_1_0_FN(0x00)
+#define SDEI_1_0_FN_SDEI_EVENT_REGISTER			SDEI_1_0_FN(0x01)
+#define SDEI_1_0_FN_SDEI_EVENT_ENABLE			SDEI_1_0_FN(0x02)
+#define SDEI_1_0_FN_SDEI_EVENT_DISABLE			SDEI_1_0_FN(0x03)
+#define SDEI_1_0_FN_SDEI_EVENT_CONTEXT			SDEI_1_0_FN(0x04)
+#define SDEI_1_0_FN_SDEI_EVENT_COMPLETE			SDEI_1_0_FN(0x05)
+#define SDEI_1_0_FN_SDEI_EVENT_COMPLETE_AND_RESUME	SDEI_1_0_FN(0x06)
+#define SDEI_1_0_FN_SDEI_EVENT_UNREGISTER		SDEI_1_0_FN(0x07)
+#define SDEI_1_0_FN_SDEI_EVENT_STATUS			SDEI_1_0_FN(0x08)
+#define SDEI_1_0_FN_SDEI_EVENT_GET_INFO			SDEI_1_0_FN(0x09)
+#define SDEI_1_0_FN_SDEI_EVENT_ROUTING_SET		SDEI_1_0_FN(0x0A)
+#define SDEI_1_0_FN_SDEI_PE_MASK			SDEI_1_0_FN(0x0B)
+#define SDEI_1_0_FN_SDEI_PE_UNMASK			SDEI_1_0_FN(0x0C)
+#define SDEI_1_0_FN_SDEI_INTERRUPT_BIND			SDEI_1_0_FN(0x0D)
+#define SDEI_1_0_FN_SDEI_INTERRUPT_RELEASE		SDEI_1_0_FN(0x0E)
+#define SDEI_1_0_FN_SDEI_PRIVATE_RESET			SDEI_1_0_FN(0x11)
+#define SDEI_1_0_FN_SDEI_SHARED_RESET			SDEI_1_0_FN(0x12)
+
+#define SDEI_VERSION_MAJOR_SHIFT			48
+#define SDEI_VERSION_MAJOR_MASK				0x7fff
+#define SDEI_VERSION_MINOR_SHIFT			32
+#define SDEI_VERSION_MINOR_MASK				0xffff
+#define SDEI_VERSION_VENDOR_SHIFT			0
+#define SDEI_VERSION_VENDOR_MASK			0xffffffff
+
+#define SDEI_VERSION_MAJOR(x)	(x>>SDEI_VERSION_MAJOR_SHIFT & SDEI_VERSION_MAJOR_MASK)
+#define SDEI_VERSION_MINOR(x)	(x>>SDEI_VERSION_MINOR_SHIFT & SDEI_VERSION_MINOR_MASK)
+#define SDEI_VERSION_VENDOR(x)	(x>>SDEI_VERSION_VENDOR_SHIFT & SDEI_VERSION_VENDOR_MASK)
+
+/* SDEI return values */
+#define SDEI_SUCCESS		0
+#define SDEI_NOT_SUPPORTED	-1
+#define SDEI_INVALID_PARAMETERS	-2
+#define SDEI_DENIED		-3
+#define SDEI_PENDING		-5
+#define SDEI_OUT_OF_RESOURCE	-10
+
+/* EVENT_REGISTER flags */
+#define SDEI_EVENT_REGISTER_RM_ANY	0
+#define SDEI_EVENT_REGISTER_RM_PE	1
+
+/* EVENT_STATUS return value bits */
+#define SDEI_EVENT_STATUS_RUNNING	2
+#define SDEI_EVENT_STATUS_ENABLED	1
+#define SDEI_EVENT_STATUS_REGISTERED	0
+
+/* EVENT_COMPLETE status values */
+#define SDEI_EV_HANDLED	0
+#define SDEI_EV_FAILED	1
+
+/* GET_INFO values */
+#define SDEI_EVENT_INFO_EV_TYPE			0
+#define SDEI_EVENT_INFO_EV_SIGNALED		1
+#define SDEI_EVENT_INFO_EV_PRIORITY		2
+#define SDEI_EVENT_INFO_EV_ROUTING_MODE		3
+#define SDEI_EVENT_INFO_EV_ROUTING_AFF		4
+
+/* and their results */
+#define SDEI_EVENT_TYPE_PRIVATE			0
+#define SDEI_EVENT_TYPE_SHARED			1
+#define SDEI_EVENT_PRIORITY_NORMAL		0
+#define SDEI_EVENT_PRIORITY_CRITICAL		1
+
+#endif /* _UAPI_LINUX_ARM_SDEI_H */