[PATCH v5 2/2] ACPI: AGDI: Add support for Arm Generic Diagnostic Dump and Reset device

[Ilkka Koskinen]

ACPI for Arm Components 1.1 Platform Design Document v1.1 [0] specifices
Arm Generic Diagnostic Device Interface (AGDI). It allows an admin to
issue diagnostic dump and reset via an SDEI event or an interrupt.
This patch implements SDEI path.

[0] https://developer.arm.com/documentation/den0093/latest/

Signed-off-by: Ilkka Koskinen <ilkka at os.amperecomputing.com>
---
 drivers/acpi/arm64/Kconfig  | 10 +++++++
 drivers/acpi/arm64/Makefile |  1 +
 drivers/acpi/arm64/agdi.c   | 52 +++++++++++++++++++++++++++++++++++++
 drivers/acpi/bus.c          |  2 ++
 include/linux/acpi_agdi.h   | 13 ++++++++++
 5 files changed, 78 insertions(+)
 create mode 100644 drivers/acpi/arm64/agdi.c
 create mode 100644 include/linux/acpi_agdi.h

diff --git a/drivers/acpi/arm64/Kconfig b/drivers/acpi/arm64/Kconfig
index 6dba187f4f2e..d4a72835f328 100644
--- a/drivers/acpi/arm64/Kconfig
+++ b/drivers/acpi/arm64/Kconfig
@@ -8,3 +8,13 @@ config ACPI_IORT
 
 config ACPI_GTDT
 	bool
+
+config ACPI_AGDI
+	bool "Arm Generic Diagnostic Dump and Reset Device Interface"
+	depends on ARM_SDE_INTERFACE
+	help
+	  Arm Generic Diagnostic Dump and Reset Device Interface (AGDI) is
+	  a standard that enables issuing a non-maskable diagnostic dump and
+	  reset command.
+
+	  If set, the kernel parses AGDI table and listens for the command.
diff --git a/drivers/acpi/arm64/Makefile b/drivers/acpi/arm64/Makefile
index 66acbe77f46e..7b9e4045659d 100644
--- a/drivers/acpi/arm64/Makefile
+++ b/drivers/acpi/arm64/Makefile
@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_ACPI_AGDI) 	+= agdi.o
 obj-$(CONFIG_ACPI_IORT) 	+= iort.o
 obj-$(CONFIG_ACPI_GTDT) 	+= gtdt.o
 obj-y				+= dma.o
diff --git a/drivers/acpi/arm64/agdi.c b/drivers/acpi/arm64/agdi.c
new file mode 100644
index 000000000000..28916650d834
--- /dev/null
+++ b/drivers/acpi/arm64/agdi.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * This file implements handling of
+ * Arm Generic Diagnostic Dump and Reset Interface table (AGDI)
+ *
+ * Copyright (c) 2022, Ampere Computing LLC
+ */
+
+#define pr_fmt(fmt) "ACPI: AGDI: " fmt
+
+#include <linux/acpi.h>
+#include <linux/arm_sdei.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+
+static int agdi_sdei_handler(u32 sdei_event, struct pt_regs *regs, void *arg)
+{
+	nmi_panic(regs, "Arm Generic Diagnostic Dump and Reset SDEI event issued");
+	return 0;
+}
+
+void __init acpi_agdi_init(void)
+{
+	struct acpi_table_agdi *agdi_table;
+	acpi_status status;
+	int sdei_event;
+
+	status = acpi_get_table(ACPI_SIG_AGDI, 0,
+				(struct acpi_table_header **) &agdi_table);
+	if (ACPI_FAILURE(status))
+		return;
+
+	if (agdi_table->flags & ACPI_AGDI_SIGNALING_MODE) {
+		pr_warn("Interrupt signaling is not supported");
+		acpi_put_table((struct acpi_table_header *)agdi_table);
+		return;
+	}
+
+	sdei_event = agdi_table->sdei_event;
+	acpi_put_table((struct acpi_table_header *)agdi_table);
+
+	if (sdei_event_register(sdei_event, agdi_sdei_handler, NULL)) {
+		pr_err("Failed to register for SDEI event %d", sdei_event);
+		return;
+	}
+
+	if (sdei_event_enable(sdei_event)) {
+		pr_err("Failed to enable SDEI event %d\n", sdei_event);
+		sdei_event_unregister(sdei_event);
+		return;
+	}
+}
diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index cd374210fb9f..747a7f98fc1b 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -26,6 +26,7 @@
 #include <asm/mpspec.h>
 #include <linux/dmi.h>
 #endif
+#include <linux/acpi_agdi.h>
 #include <linux/acpi_iort.h>
 #include <linux/acpi_viot.h>
 #include <linux/pci.h>
@@ -1341,6 +1342,7 @@ static int __init acpi_init(void)
 	acpi_debugger_init();
 	acpi_setup_sb_notify_handler();
 	acpi_viot_init();
+	acpi_agdi_init();
 	return 0;
 }
 
diff --git a/include/linux/acpi_agdi.h b/include/linux/acpi_agdi.h
new file mode 100644
index 000000000000..f477f0b452fa
--- /dev/null
+++ b/include/linux/acpi_agdi.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef __ACPI_AGDI_H__
+#define __ACPI_AGDI_H__
+
+#include <linux/acpi.h>
+
+#ifdef CONFIG_ACPI_AGDI
+void __init acpi_agdi_init(void);
+#else
+static inline void acpi_agdi_init(void) {}
+#endif
+#endif /* __ACPI_AGDI_H__ */
-- 
2.17.1