nvidia-g210m-acpi/nvidia_g210m_acpi.c

   1 /*
   2  * Linux kernel module that disables the discrete graphics board
   3  *
   4  * Original version for Lenovo laptops by Sylvain Joyeux <sylvain.joyeux@m4x.org> Copyright (c) 2009
   5  *
   6  * mil2 added nVidia GeForce G210M support (for Asus UL30VT, UL50V, UL80V laptops)
   7  * o8x8 added post hibernate support
   8  *
   9  * Marco Giorgi <blackmoon.105@gmail.com> packaged this module for debian/ubuntu
  10  *
  11  * Power down the nVidia card to save up to 4W of power.
  12  *
  13  */
  14
  15
  16 /*
  17  *  Name: nvidia_g210m_acpi.c
  18  *  Source code for nvidia_g210m_acpi switch-off kernel module
  19  *
  20  *  Licensed under the GNU GPL
  21  *
  22  */
  23
  24
  25 #include <acpi/acpi.h>
  26 #include <linux/suspend.h>
  27
  28 MODULE_LICENSE("GPL");
  29
  30 static acpi_handle root_handle;
  31
  32 static int kill_nvidia(void)
  33 {
  34     acpi_status status;
  35     // The device handle
  36     acpi_handle handle;
  37     struct acpi_object_list args;
  38     // For the return value
  39     struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
  40
  41     status = acpi_get_handle(root_handle, "\\_SB.PCI0.P0P1.VGA._OFF", &handle);
  42     if (ACPI_FAILURE(status))
  43     {
  44         printk("%s: cannot get ACPI handle: %s\n", __func__, acpi_format_exception(status));
  45         return -ENOSYS;
  46     }
  47
  48     args.count = 0;
  49     args.pointer = NULL;
  50
  51     status = acpi_evaluate_object(handle, NULL, &args, &buffer);
  52     if (ACPI_FAILURE(status))
  53     {
  54         printk("%s: _OFF method call failed: %s\n", __func__, acpi_format_exception(status));
  55         return -ENOSYS;
  56     }
  57     kfree(buffer.pointer);
  58
  59     printk("%s: disabled the discrete graphics card\n", __func__);
  60     return 0;
  61 }
  62
  63 static int power_event(struct notifier_block *this, unsigned long event, void *ptr)
  64 {
  65     switch (event) {
  66         case PM_POST_HIBERNATION:
  67         printk("%s: post hibernation\n",__FILE__);
  68             kill_nvidia();
  69         break;
  70         case PM_POST_SUSPEND:
  71         printk("%s: post suspend\n",__FILE__);
  72             kill_nvidia();
  73             break;
  74         default:
  75         break;
  76     }
  77     return NOTIFY_DONE;
  78 }
  79
  80 static struct notifier_block power_notifier = { .notifier_call = power_event, };
  81
  82 static int __init nvidia_g210m_acpi(void)
  83 {
  84     int ret = register_pm_notifier(&power_notifier);
  85     if (ret) return ret;
  86     return kill_nvidia();
  87 }
  88
  89 static void dummy(void)
  90 {
  91 }
  92
  93 module_init(nvidia_g210m_acpi);
  94 module_exit(dummy);