pvpanic: pvpanic device driver

pvpanic device is a qemu simulated device through which guest panic
event is sent to host.
Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>

drivers/platform/x86/Kconfig

@@ -781,4 +781,12 @@ config APPLE_GMUX
 	  graphics as well as the backlight. Currently only backlight
 	  control is supported by the driver.
 
+config PVPANIC
+	tristate "pvpanic device support"
+	depends on ACPI
+	---help---
+	  This driver provides support for the pvpanic device.  pvpanic is
+	  a paravirtualized device provided by QEMU; it lets a virtual machine
+	  (guest) communicate panic events to the host.
+
 endif # X86_PLATFORM_DEVICES

drivers/platform/x86/Makefile

@@ -51,3 +51,5 @@ obj-$(CONFIG_INTEL_OAKTRAIL)	+= intel_oaktrail.o
 obj-$(CONFIG_SAMSUNG_Q10)	+= samsung-q10.o
 obj-$(CONFIG_APPLE_GMUX)	+= apple-gmux.o
 obj-$(CONFIG_CHROMEOS_LAPTOP)	+= chromeos_laptop.o
+
+obj-$(CONFIG_PVPANIC)           += pvpanic.o

drivers/platform/x86/pvpanic.c

+/*
+ *  pvpanic.c - pvpanic Device Support
+ *
+ *  Copyright (C) 2013 Fujitsu.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <acpi/acpi_bus.h>
+#include <acpi/acpi_drivers.h>
+
+MODULE_AUTHOR("Hu Tao <hutao@cn.fujitsu.com>");
+MODULE_DESCRIPTION("pvpanic device driver");
+MODULE_LICENSE("GPL");
+
+static int pvpanic_add(struct acpi_device *device);
+static int pvpanic_remove(struct acpi_device *device);
+
+static const struct acpi_device_id pvpanic_device_ids[] = {
+	{ "QEMU0001", 0 },
+	{ "", 0 },
+};
+MODULE_DEVICE_TABLE(acpi, pvpanic_device_ids);
+
+#define PVPANIC_PANICKED	(1 << 0)
+
+static u16 port;
+
+static struct acpi_driver pvpanic_driver = {
+	.name =		"pvpanic",
+	.class =	"QEMU",
+	.ids =		pvpanic_device_ids,
+	.ops =		{
+				.add =		pvpanic_add,
+				.remove =	pvpanic_remove,
+			},
+	.owner =	THIS_MODULE,
+};
+
+static void
+pvpanic_send_event(unsigned int event)
+{
+	outb(event, port);
+}
+
+static int
+pvpanic_panic_notify(struct notifier_block *nb, unsigned long code,
+		     void *unused)
+{
+	pvpanic_send_event(PVPANIC_PANICKED);
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block pvpanic_panic_nb = {
+	.notifier_call = pvpanic_panic_notify,
+};
+
+
+static acpi_status
+pvpanic_walk_resources(struct acpi_resource *res, void *context)
+{
+	switch (res->type) {
+	case ACPI_RESOURCE_TYPE_END_TAG:
+		return AE_OK;
+
+	case ACPI_RESOURCE_TYPE_IO:
+		port = res->data.io.minimum;
+		return AE_OK;
+
+	default:
+		return AE_ERROR;
+	}
+}
+
+static int pvpanic_add(struct acpi_device *device)
+{
+	acpi_status status;
+	u64 ret;
+
+	status = acpi_evaluate_integer(device->handle, "_STA", NULL,
+				       &ret);
+
+	if (ACPI_FAILURE(status) || (ret & 0x0B) != 0x0B)
+		return -ENODEV;
+
+	acpi_walk_resources(device->handle, METHOD_NAME__CRS,
+			    pvpanic_walk_resources, NULL);
+
+	if (!port)
+		return -ENODEV;
+
+	atomic_notifier_chain_register(&panic_notifier_list,
+				       &pvpanic_panic_nb);
+
+	return 0;
+}
+
+static int pvpanic_remove(struct acpi_device *device)
+{
+
+	atomic_notifier_chain_unregister(&panic_notifier_list,
+					 &pvpanic_panic_nb);
+	return 0;
+}
+
+module_acpi_driver(pvpanic_driver);