drm/stm: add sleep power management

Implements system sleep power management ops.
Signed-off-by: Yannick Fertré <yannick.fertre@st.com>
Acked-by: Philippe Cornu <philippe.cornu@st.com>
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1553156120-13851-1-git-send-email-yannick.fertre@st.com

drivers/gpu/drm/stm/drv.c

@@ -129,6 +129,40 @@ static void drv_unload(struct drm_device *ddev)
 	drm_mode_config_cleanup(ddev);
 }
 
+static __maybe_unused int drv_suspend(struct device *dev)
+{
+	struct drm_device *ddev = dev_get_drvdata(dev);
+	struct ltdc_device *ldev = ddev->dev_private;
+	struct drm_atomic_state *state;
+
+	drm_kms_helper_poll_disable(ddev);
+	state = drm_atomic_helper_suspend(ddev);
+	if (IS_ERR(state)) {
+		drm_kms_helper_poll_enable(ddev);
+		return PTR_ERR(state);
+	}
+	ldev->suspend_state = state;
+	ltdc_suspend(ddev);
+
+	return 0;
+}
+
+static __maybe_unused int drv_resume(struct device *dev)
+{
+	struct drm_device *ddev = dev_get_drvdata(dev);
+	struct ltdc_device *ldev = ddev->dev_private;
+
+	ltdc_resume(ddev);
+	drm_atomic_helper_resume(ddev, ldev->suspend_state);
+	drm_kms_helper_poll_enable(ddev);
+
+	return 0;
+}
+
+static const struct dev_pm_ops drv_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(drv_suspend, drv_resume)
+};
+
 static int stm_drm_platform_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -186,6 +220,7 @@ static struct platform_driver stm_drm_platform_driver = {
 	.driver = {
 		.name = "stm32-display",
 		.of_match_table = drv_dt_ids,
+		.pm = &drv_pm_ops,
 	},
 };
 

drivers/gpu/drm/stm/ltdc.c

@@ -1062,6 +1062,30 @@ static int ltdc_get_caps(struct drm_device *ddev)
 	return 0;
 }
 
+void ltdc_suspend(struct drm_device *ddev)
+{
+	struct ltdc_device *ldev = ddev->dev_private;
+
+	DRM_DEBUG_DRIVER("\n");
+	clk_disable_unprepare(ldev->pixel_clk);
+}
+
+int ltdc_resume(struct drm_device *ddev)
+{
+	struct ltdc_device *ldev = ddev->dev_private;
+	int ret;
+
+	DRM_DEBUG_DRIVER("\n");
+
+	ret = clk_prepare_enable(ldev->pixel_clk);
+	if (ret) {
+		DRM_ERROR("failed to enable pixel clock (%d)\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
 int ltdc_load(struct drm_device *ddev)
 {
 	struct platform_device *pdev = to_platform_device(ddev->dev);

drivers/gpu/drm/stm/ltdc.h

@@ -36,6 +36,7 @@ struct ltdc_device {
 	u32 error_status;
 	u32 irq_status;
 	struct fps_info plane_fpsi[LTDC_MAX_LAYER];
+	struct drm_atomic_state *suspend_state;
 };
 
 bool ltdc_crtc_scanoutpos(struct drm_device *dev, unsigned int pipe,
@@ -45,5 +46,7 @@ bool ltdc_crtc_scanoutpos(struct drm_device *dev, unsigned int pipe,
 
 int ltdc_load(struct drm_device *ddev);
 void ltdc_unload(struct drm_device *ddev);
+void ltdc_suspend(struct drm_device *ddev);
+int ltdc_resume(struct drm_device *ddev);
 
 #endif