drm/msm: add headless gpu device for imx5

This patch allows using drm/msm without qcom display hardware. It adds a
amd,imageon compatible, which is used instead of qcom,adreno, but does
not require a top level msm node.
Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/Kconfig

@@ -2,7 +2,7 @@
 config DRM_MSM
 	tristate "MSM DRM"
 	depends on DRM
-	depends on ARCH_QCOM || (ARM && COMPILE_TEST)
+	depends on ARCH_QCOM || SOC_IMX5 || (ARM && COMPILE_TEST)
 	depends on OF && COMMON_CLK
 	depends on MMU
 	select QCOM_MDT_LOADER if ARCH_QCOM
@@ -11,7 +11,7 @@ config DRM_MSM
 	select DRM_PANEL
 	select SHMEM
 	select TMPFS
-	select QCOM_SCM
+	select QCOM_SCM if ARCH_QCOM
 	select WANT_DEV_COREDUMP
 	select SND_SOC_HDMI_CODEC if SND_SOC
 	select SYNC_FILE

drivers/gpu/drm/msm/adreno/adreno_device.c

@@ -271,7 +271,8 @@ static int find_chipid(struct device *dev, struct adreno_rev *rev)
 	if (ret == 0) {
 		unsigned int r, patch;
 
-		if (sscanf(compat, "qcom,adreno-%u.%u", &r, &patch) == 2) {
+		if (sscanf(compat, "qcom,adreno-%u.%u", &r, &patch) == 2 ||
+		    sscanf(compat, "amd,imageon-%u.%u", &r, &patch) == 2) {
 			rev->core = r / 100;
 			r %= 100;
 			rev->major = r / 10;
@@ -359,9 +360,37 @@ static const struct component_ops a3xx_ops = {
 		.unbind = adreno_unbind,
 };
 
+static void adreno_device_register_headless(void)
+{
+	/* on imx5, we don't have a top-level mdp/dpu node
+	 * this creates a dummy node for the driver for that case
+	 */
+	struct platform_device_info dummy_info = {
+		.parent = NULL,
+		.name = "msm",
+		.id = -1,
+		.res = NULL,
+		.num_res = 0,
+		.data = NULL,
+		.size_data = 0,
+		.dma_mask = ~0,
+	};
+	platform_device_register_full(&dummy_info);
+}
+
 static int adreno_probe(struct platform_device *pdev)
 {
-	return component_add(&pdev->dev, &a3xx_ops);
+
+	int ret;
+
+	ret = component_add(&pdev->dev, &a3xx_ops);
+	if (ret)
+		return ret;
+
+	if (of_device_is_compatible(pdev->dev.of_node, "amd,imageon"))
+		adreno_device_register_headless();
+
+	return 0;
 }
 
 static int adreno_remove(struct platform_device *pdev)
@@ -373,6 +402,8 @@ static int adreno_remove(struct platform_device *pdev)
 static const struct of_device_id dt_match[] = {
 	{ .compatible = "qcom,adreno" },
 	{ .compatible = "qcom,adreno-3xx" },
+	/* for compatibility with imx5 gpu: */
+	{ .compatible = "amd,imageon" },
 	/* for backwards compat w/ downstream kgsl DT files: */
 	{ .compatible = "qcom,kgsl-3d0" },
 	{}

drivers/gpu/drm/msm/msm_debugfs.c

@@ -235,7 +235,7 @@ int msm_debugfs_init(struct drm_minor *minor)
 	debugfs_create_file("gpu", S_IRUSR, minor->debugfs_root,
 		dev, &msm_gpu_fops);
 
-	if (priv->kms->funcs->debugfs_init) {
+	if (priv->kms && priv->kms->funcs->debugfs_init) {
 		ret = priv->kms->funcs->debugfs_init(priv->kms, minor);
 		if (ret)
 			return ret;

drivers/gpu/drm/msm/msm_drv.c

@@ -520,17 +520,13 @@ static int msm_drm_init(struct device *dev, struct drm_driver *drv)
 		priv->kms = kms;
 		break;
 	default:
-		kms = ERR_PTR(-ENODEV);
+		/* valid only for the dummy headless case, where of_node=NULL */
+		WARN_ON(dev->of_node);
+		kms = NULL;
 		break;
 	}
 
 	if (IS_ERR(kms)) {
-		/*
-		 * NOTE: once we have GPU support, having no kms should not
-		 * be considered fatal.. ideally we would still support gpu
-		 * and (for example) use dmabuf/prime to share buffers with
-		 * imx drm driver on iMX5
-		 */
 		DRM_DEV_ERROR(dev, "failed to load kms\n");
 		ret = PTR_ERR(kms);
 		priv->kms = NULL;
@@ -648,7 +644,7 @@ static int msm_drm_init(struct device *dev, struct drm_driver *drv)
 	drm_mode_config_reset(ddev);
 
 #ifdef CONFIG_DRM_FBDEV_EMULATION
-	if (fbdev)
+	if (kms && fbdev)
 		priv->fbdev = msm_fbdev_init(ddev);
 #endif
 
@@ -1332,6 +1328,7 @@ static int add_display_components(struct device *dev,
 static const struct of_device_id msm_gpu_match[] = {
 	{ .compatible = "qcom,adreno" },
 	{ .compatible = "qcom,adreno-3xx" },
+	{ .compatible = "amd,imageon" },
 	{ .compatible = "qcom,kgsl-3d0" },
 	{ },
 };
@@ -1376,9 +1373,11 @@ static int msm_pdev_probe(struct platform_device *pdev)
 	struct component_match *match = NULL;
 	int ret;
 
-	ret = add_display_components(&pdev->dev, &match);
-	if (ret)
-		return ret;
+	if (get_mdp_ver(pdev)) {
+		ret = add_display_components(&pdev->dev, &match);
+		if (ret)
+			return ret;
+	}
 
 	ret = add_gpu_components(&pdev->dev, &match);
 	if (ret)