1. 根目录:
2. drivers
3. gpu
4. drm
5. nouveau
6. nouveau_vga.c

#include <linux/vgaarb.h>
#include <linux/vga_switcheroo.h>

#include <drm/drmP.h>
#include <drm/drm_crtc_helper.h>

#include "nouveau_drm.h"
#include "nouveau_acpi.h"
#include "nouveau_fbcon.h"
#include "nouveau_vga.h"

static unsigned int
nouveau_vga_set_decode(void *priv, bool state)
{
	struct nouveau_device *device = nouveau_dev(priv);

	if (device->chipset >= 0x40)
		nv_wr32(device, 0x088054, state);
	else
		nv_wr32(device, 0x001854, state);

	if (state)
		return VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
		       VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
	else
		return VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
}

static void
nouveau_switcheroo_set_state(struct pci_dev *pdev,
			     enum vga_switcheroo_state state)
{
	struct drm_device *dev = pci_get_drvdata(pdev);

	if (state == VGA_SWITCHEROO_ON) {
		printk(KERN_ERR "VGA switcheroo: switched nouveau on\n");
		dev->switch_power_state = DRM_SWITCH_POWER_CHANGING;
		nouveau_pmops_resume(&pdev->dev);
		drm_kms_helper_poll_enable(dev);
		dev->switch_power_state = DRM_SWITCH_POWER_ON;
	} else {
		printk(KERN_ERR "VGA switcheroo: switched nouveau off\n");
		dev->switch_power_state = DRM_SWITCH_POWER_CHANGING;
		drm_kms_helper_poll_disable(dev);
		nouveau_switcheroo_optimus_dsm();
		nouveau_pmops_suspend(&pdev->dev);
		dev->switch_power_state = DRM_SWITCH_POWER_OFF;
	}
}

static void
nouveau_switcheroo_reprobe(struct pci_dev *pdev)
{
	struct drm_device *dev = pci_get_drvdata(pdev);
	nouveau_fbcon_output_poll_changed(dev);
}

static bool
nouveau_switcheroo_can_switch(struct pci_dev *pdev)
{
	struct drm_device *dev = pci_get_drvdata(pdev);
	bool can_switch;

	spin_lock(&dev->count_lock);
	can_switch = (dev->open_count == 0);
	spin_unlock(&dev->count_lock);
	return can_switch;
}

static const struct vga_switcheroo_client_ops
nouveau_switcheroo_ops = {
	.set_gpu_state = nouveau_switcheroo_set_state,
	.reprobe = nouveau_switcheroo_reprobe,
	.can_switch = nouveau_switcheroo_can_switch,
};

void
nouveau_vga_init(struct nouveau_drm *drm)
{
	struct drm_device *dev = drm->dev;
	vga_client_register(dev->pdev, dev, NULL, nouveau_vga_set_decode);
	vga_switcheroo_register_client(dev->pdev, &nouveau_switcheroo_ops);
}

void
nouveau_vga_fini(struct nouveau_drm *drm)
{
	struct drm_device *dev = drm->dev;
	vga_switcheroo_unregister_client(dev->pdev);
	vga_client_register(dev->pdev, NULL, NULL, NULL);
}


void
nouveau_vga_lastclose(struct drm_device *dev)
{
	vga_switcheroo_process_delayed_switch();
}