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         .priority = 1, /* let this called before broken drm_fb_helper */
  74 };
  75
  76
  77 static acpi_status
  78 pvpanic_walk_resources(struct acpi_resource *res, void *context)
  79 {
  80         switch (res->type) {
  81         case ACPI_RESOURCE_TYPE_END_TAG:
  82                 return AE_OK;
  83
  84         case ACPI_RESOURCE_TYPE_IO:
  85                 port = res->data.io.minimum;
  86                 return AE_OK;
  87
  88         default:
  89                 return AE_ERROR;
  90         }
  91 }
  92
  93 static int pvpanic_add(struct acpi_device *device)
  94 {
  95         int ret;
  96
  97         ret = acpi_bus_get_status(device);
  98         if (ret < 0)
  99                 return ret;
 100
 101         if (!device->status.enabled || !device->status.functional)
 102                 return -ENODEV;
 103
 104         acpi_walk_resources(device->handle, METHOD_NAME__CRS,
 105                             pvpanic_walk_resources, NULL);
 106
 107         if (!port)
 108                 return -ENODEV;
 109
 110         atomic_notifier_chain_register(&panic_notifier_list,
 111                                        &pvpanic_panic_nb);
 112
 113         return 0;
 114 }
 115
 116 static int pvpanic_remove(struct acpi_device *device)
 117 {
 118
 119         atomic_notifier_chain_unregister(&panic_notifier_list,
 120                                          &pvpanic_panic_nb);
 121         return 0;
 122 }
 123
 124 module_acpi_driver(pvpanic_driver);