drivers/platform/x86/pvpanic.c

   1 /*
   2  *  pvpanic.c - pvpanic Device Support
   3  *
   4  *  Copyright (C) 2013 Fujitsu.
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; either version 2 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  19  */
  20
  21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  22
  23 #include <linux/kernel.h>
  24 #include <linux/module.h>
  25 #include <linux/init.h>
  26 #include <linux/types.h>
  27 #include <linux/acpi.h>
  28
  29 MODULE_AUTHOR("Hu Tao <hutao@cn.fujitsu.com>");
  30 MODULE_DESCRIPTION("pvpanic device driver");
  31 MODULE_LICENSE("GPL");
  32
  33 static int pvpanic_add(struct acpi_device *device);
  34 static int pvpanic_remove(struct acpi_device *device);
  35
  36 static const struct acpi_device_id pvpanic_device_ids[] = {
  37         { "QEMU0001", 0 },
  38         { "", 0 },
  39 };
  40 MODULE_DEVICE_TABLE(acpi, pvpanic_device_ids);
  41
  42 #define PVPANIC_PANICKED        (1 << 0)
  43
  44 static u16 port;
  45
  46 static struct acpi_driver pvpanic_driver = {
  47         .name =         "pvpanic",
  48         .class =        "QEMU",
  49         .ids =          pvpanic_device_ids,
  50         .ops =          {
  51                                 .add =          pvpanic_add,
  52                                 .remove =       pvpanic_remove,
  53                         },
  54         .owner =        THIS_MODULE,
  55 };
  56
  57 static void
  58 pvpanic_send_event(unsigned int event)
  59 {
  60         outb(event, port);
  61 }
  62
  63 static int
  64 pvpanic_panic_notify(struct notifier_block *nb, unsigned long code,
  65                      void *unused)
  66 {
  67         pvpanic_send_event(PVPANIC_PANICKED);
  68         return NOTIFY_DONE;
  69 }
  70
  71 static struct notifier_block pvpanic_panic_nb = {
  72         .notifier_call = pvpanic_panic_notify,
  73 };
  74
  75
  76 static acpi_status
  77 pvpanic_walk_resources(struct acpi_resource *res, void *context)
  78 {
  79         switch (res->type) {
  80         case ACPI_RESOURCE_TYPE_END_TAG:
  81                 return AE_OK;
  82
  83         case ACPI_RESOURCE_TYPE_IO:
  84                 port = res->data.io.minimum;
  85                 return AE_OK;
  86
  87         default:
  88                 return AE_ERROR;
  89         }
  90 }
  91
  92 static int pvpanic_add(struct acpi_device *device)
  93 {
  94         acpi_status status;
  95         u64 ret;
  96
  97         status = acpi_evaluate_integer(device->handle, "_STA", NULL,
  98                                        &ret);
  99
 100         if (ACPI_FAILURE(status) || (ret & 0x0B) != 0x0B)
 101                 return -ENODEV;
 102
 103         acpi_walk_resources(device->handle, METHOD_NAME__CRS,
 104                             pvpanic_walk_resources, NULL);
 105
 106         if (!port)
 107                 return -ENODEV;
 108
 109         atomic_notifier_chain_register(&panic_notifier_list,
 110                                        &pvpanic_panic_nb);
 111
 112         return 0;
 113 }
 114
 115 static int pvpanic_remove(struct acpi_device *device)
 116 {
 117
 118         atomic_notifier_chain_unregister(&panic_notifier_list,
 119                                          &pvpanic_panic_nb);
 120         return 0;
 121 }
 122
 123 module_acpi_driver(pvpanic_driver);