ACPI: AGDI: Add driver for Arm Generic Diagnostic Dump and Reset device

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@os.amperecomputing.com>
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

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.

drivers/acpi/arm64/Makefile

 # 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

drivers/acpi/arm64/agdi.c

+// 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>
+#include <linux/platform_device.h>
+
+struct agdi_data {
+	int sdei_event;
+};
+
+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;
+}
+
+static int agdi_sdei_probe(struct platform_device *pdev,
+			   struct agdi_data *adata)
+{
+	int err;
+
+	err = sdei_event_register(adata->sdei_event, agdi_sdei_handler, pdev);
+	if (err) {
+		dev_err(&pdev->dev, "Failed to register for SDEI event %d",
+			adata->sdei_event);
+		return err;
+	}
+
+	err = sdei_event_enable(adata->sdei_event);
+	if (err)  {
+		sdei_event_unregister(adata->sdei_event);
+		dev_err(&pdev->dev, "Failed to enable event %d\n",
+			adata->sdei_event);
+		return err;
+	}
+
+	return 0;
+}
+
+static int agdi_probe(struct platform_device *pdev)
+{
+	struct agdi_data *adata = dev_get_platdata(&pdev->dev);
+
+	if (!adata)
+		return -EINVAL;
+
+	return agdi_sdei_probe(pdev, adata);
+}
+
+static int agdi_remove(struct platform_device *pdev)
+{
+	struct agdi_data *adata = dev_get_platdata(&pdev->dev);
+	int err, i;
+
+	err = sdei_event_disable(adata->sdei_event);
+	if (err)
+		return err;
+
+	for (i = 0; i < 3; i++) {
+		err = sdei_event_unregister(adata->sdei_event);
+		if (err != -EINPROGRESS)
+			break;
+
+		schedule();
+	}
+
+	return err;
+}
+
+static struct platform_driver agdi_driver = {
+	.driver = {
+		.name = "agdi",
+	},
+	.probe = agdi_probe,
+	.remove = agdi_remove,
+};
+
+void __init acpi_agdi_init(void)
+{
+	struct acpi_table_agdi *agdi_table;
+	struct agdi_data pdata;
+	struct platform_device *pdev;
+	acpi_status status;
+
+	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");
+		goto err_put_table;
+	}
+
+	pdata.sdei_event = agdi_table->sdei_event;
+
+	pdev = platform_device_register_data(NULL, "agdi", 0, &pdata, sizeof(pdata));
+	if (IS_ERR(pdev))
+		goto err_put_table;
+
+	if (platform_driver_register(&agdi_driver))
+		platform_device_unregister(pdev);
+
+err_put_table:
+	acpi_put_table((struct acpi_table_header *)agdi_table);
+}

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;
 }
 

include/linux/acpi_agdi.h

+/* 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__ */