drm: bochs: add power management support

bochs kms driver lacks power management support, thus
the vga display doesn't work any more after S3 resume.

Fix this by adding suspend and resume functions.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/bochs/bochs.h

 #include <linux/io.h>
 #include <linux/fb.h>
+#include <linux/console.h>
 
 #include <drm/drmP.h>
 #include <drm/drm_crtc.h>

drivers/gpu/drm/bochs/bochs_drv.c

@@ -94,6 +94,49 @@ static struct drm_driver bochs_driver = {
 	.dumb_destroy           = drm_gem_dumb_destroy,
 };
 
+/* ---------------------------------------------------------------------- */
+/* pm interface                                                           */
+
+static int bochs_pm_suspend(struct device *dev)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct drm_device *drm_dev = pci_get_drvdata(pdev);
+	struct bochs_device *bochs = drm_dev->dev_private;
+
+	drm_kms_helper_poll_disable(drm_dev);
+
+	if (bochs->fb.initialized) {
+		console_lock();
+		fb_set_suspend(bochs->fb.helper.fbdev, 1);
+		console_unlock();
+	}
+
+	return 0;
+}
+
+static int bochs_pm_resume(struct device *dev)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct drm_device *drm_dev = pci_get_drvdata(pdev);
+	struct bochs_device *bochs = drm_dev->dev_private;
+
+	drm_helper_resume_force_mode(drm_dev);
+
+	if (bochs->fb.initialized) {
+		console_lock();
+		fb_set_suspend(bochs->fb.helper.fbdev, 0);
+		console_unlock();
+	}
+
+	drm_kms_helper_poll_enable(drm_dev);
+	return 0;
+}
+
+static const struct dev_pm_ops bochs_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(bochs_pm_suspend,
+				bochs_pm_resume)
+};
+
 /* ---------------------------------------------------------------------- */
 /* pci interface                                                          */
 
@@ -155,6 +198,7 @@ static struct pci_driver bochs_pci_driver = {
 	.id_table =	bochs_pci_tbl,
 	.probe =	bochs_pci_probe,
 	.remove =	bochs_pci_remove,
+	.driver.pm =    &bochs_pm_ops,
 };
 
 /* ---------------------------------------------------------------------- */